Thermal separation method for separating at least one mass flow, concentrated with acrylic acid

FIELD: chemistry.

SUBSTANCE: invention relates to a thermal separation method using fractional condensation of a product-gas mixture, obtained through heterogeneous catalysed partial oxidation of propene and/or propane in gaseous phase to acrylic acid, for separating at least one mass flow, concentrated with acrylic acid, from a product-gas mixture containing acrylic acid, which involves continuous static operation of at least one device for thermal separation, containing at least one effective separation chamber with a fractionation column which has mass-transfer trays as built-in separating elements, in which the product-gas mixture is loaded, containing acrylic acid as at least one mass flow, and from which at least one mass flow containing acrylic acid is unloaded under the condition that, the overall mass flow loaded into the effective separation chamber and obtained from combining separate mass flows loaded into the separating chamber, contains X wt % components distinct from acrylic acid, the mass flow which is unloaded from the effective separation chamber with the largest content of acrylic acid, contains Y wt % components distinct from acrylic acid, ratio X:Y is ≥5, effective separation chamber, except the loading and unloading place, is bordered by a solid phase and contains, besides the mass-exchange trays as built-in separating elements in the fractionation column, at least one circulating heat exchanger, and total volume of the chamber, filled with liquid phase, is ≥1 m3, wherein temperature of the liquid phase is at least partially ≥80°C, when the effective separation chamber is divided into n separate volume elements, wherein the highest and lowest temperature of liquid phase in a separate volume element differ by not more than 2°C, and the volume element in the effective separation chamber is solid, total dwell time ttotal.

≤20 h, where A = (Ti-To)/10°C, To= 100°C, Ti = arithmetic mean value of the highest and lowest temperature of the ith volume element in the liquid phase in °C, msi = total mass of acrylic acid in the volume of the liquid phase of the ith volume element, mi = total liquid phase mass unloaded from the ith volume element, and is the sum of all volume elements i, under the condition that, volume elements i with liquid phase mass mi and as volume elements with a dead zone are also not included in the sum of all volume elements i, as well as volume elements i, which do not contain liquid phase, and total amount of liquid phase contained in volume elements with a dead zone is not more than 5 wt % of the total amount of liquid phase contained in the effective separation chamber.

EFFECT: separation of mass flow concentrated with acrylic acid.

10 cl, 12 dwg, 2 ex, 2 tbl

 

The present invention relates to a technology for the separation of substances, more specifically, thermal separation processes fractional condensation of a mixture of the product gas obtained heterogeneous catalyzed partial oxidation in the gas phase of propene and/or propane to acrylic acid, for separating at least one mass flow of enriched acrylic acid.

A known way of separating (meth)acrylic acid or (meth)acrolein of a mixture of the product gas, which is obtained by catalytic oxidation in the gas phase propane and/or propene, which is that the first (meth)acrylic acid and/or (meth)acrolein is separated by absorption in a solvent (e.g. water or an organic solvent) or by fractional condensation of a mixture of the product gas, and then dropped into the sediment condensate or absorbed completely separated by distillation (usually in several stages), with more or less pure (meth)acrylic acid or (meth)acrolein (see, for example, EP-A 717019, EP-A 1125912, EP-A 982289, EP-A 982287, DE-A 19606877, DE-A 1011527, DE-A 10224341, DE-AND 10218419, DE-A 10247240 and DE-A 10243625).

The above-mentioned fractional condensation differs from the usual rectification, mainly the fact that you want to split the mixture is fed to an effective separation chamber in gaseous form (i.e. fully converted into steam fo the mu).

Above containing (meth)acrylic monomers gaseous and/or liquid mixture may contain (meth)acrylic monomers as in more or less pure and diluted form (for example, solvent or gas-thinners). This solvent can be both liquid and organic, and type of organic solvent, as a rule, is not significant. Gas diluent may be, for example, nitrogen, carbon oxide (CO, CO2), oxygen, hydrocarbon, or mixture of these gases.

This means that to obtain (selection) (meth)acrylic monomers using various thermal methods of separation (described above) from a gaseous and/or liquid mixtures of substances, the content of (meth)acrylic monomers which may be 2 wt.%, or ≥10 wt.%, or ≥20 wt.% or ≥40 wt.%, or ≥60 wt.%, or ≥80 wt.%, or ≥90 wt.%, or ≥95 wt.%, or ≥99 wt.% (of course, the content of (meth)acrylic monomers is always ≤100 wt.%). Often the content of the (meth)acrylic monomers such mixtures is from 10 to 40 wt.% or from 90 to 99.5 wt.%.

Typically, such mixtures of substances in the process according to the invention as a mass flow containing (meth)acrylic monomers, served in at least one effective separating chamber.

Often effective separating chamber in the above-described heat is x the methods of separation contains a distillation column. Thus the enrichment of the (meth)acrylic monomers may be in the head, and the cube of the distillation column. Of course, at the top, bottom or middle part of a distillation column can be selected fractions enriched (meth)acrylic monomers.

Built-in efficient separating chamber, such as the separation column, the separation elements, optionally used in effective separation chamber, the implementation of the methods of thermal separation is intended to increase the surface required for heat and mass transfer.

Such built-dividing elements can be, for example, gaskets, nozzles and/or mass transfer plates.

Especially often as distillation columns with integrated dividers in the implementation of the methods of thermal separation is used such that as at least one part of the built-dividing elements contain a sequence of mass transfer plates.

Mass transfer plates are used to ensure in a distillation column in the form of liquid layers seats with closed liquid phases. When this surface steam or gas stream, rising in the fluid layer and pulverised in a closed liquid phase, is the surface exchange. Plates suppose the equipment is snug against the wall. Classical plate is plate / tube sheet. Beneath it, in this context, it should be understood plates, which as a place of passage of the upward flow of the gas or vapor phase (the term "gas" and "steam" is used in this context as synonyms) contain simple holes and/or slots.

When this plate / tube sheet, as a rule, divided into two groups, namely: forced flow of the liquid and without forced fluid supply.

In General forced fluid supply / tube sheet plates obtained by equipping mass transfer plates, at least one drain mine (outflow)through which the fluid regardless of the direction of the steam flow flowing from above to below the plates (flow). Horizontal fluid flow in the direction from the inflow to outflow is chosen in accordance with the underlying the way the task. The gas or vapor passes through the open cross-section of the plate of the dish.

If through the plate serves fluid in reverse flow (inflow and outflow plate placed on one side of the plate), we are talking about the plates return flows. In the case of plates radial flow fluid flows radially from the middle (inflow) to the outflow at the edge of the dish.

Under the plates with transverse current understand that the fluid is considered throughout the area flowed the honor, flows across the plate from inflow to outflow. Typically, plates with transverse current are single-threaded. This means that the inflow and outflow placed on opposite sides of the plate. Although they can be also a two-line (or multi-threaded). In this case, the flow may, for example, be placed in the center, and each outflow on opposite sides of the plate.

Thus, in the case / tube sheet plates force the flow of liquid is produced by equipment / tube sheet plates along with places of passage of the upward flow of the gas or vapor phase, at least one drain mine (outflow)through which the fluid regardless of the direction of the steam flow flowing from above to below the plates (flow). The fluid flows, for example, transverse current through the plate from at least one of the inflow to, at least one outflow, and the inlet and outlet pipe ensure the liquid valve and the required level of liquid in the dish. Often (especially in small diameter columns) / tube sheet plate with a forced flow of liquid are single-threaded, that is, the inflow and outflow placed on opposite sides of the plate. Although they can be also a two-line (or multi-threaded). In this case, the flow may, for example, be placed in the center, and each Otto is - on opposite sides of the plate. Thus, such plate / tube sheet then you should call push / tube sheet plates. When using the "sprinkler" fluid dampening effect of the separation, it is impossible to prevent with the help of pipes for exhaust gases (as in the case of hydraulically sealed plates with transverse current), which are through holes, this requires a minimum load on the vapor phase. Pairs of upward flow passes through the through hole and drop by drop flows through the layer of liquid discharge pipe.

A two-line or sprinkler / tube sheet plates differ from force plates so that they do not contain the final segment. Due to the lack of final segments (drain mines) the upward flow of gas sprinkler / tube sheet plates and downward flow of the liquid of the distillation column are passed through the same passages plates. In the case of sprinkler / tube sheet plates, as in the case of forced / tube sheet plates, to achieve the desired effect separation they require a minimum load steam phase. If this load is significantly diminished, the upward flow of gas and the downward reverse flow without exchange are past each other, resulting in the danger of drying plates.

This means that if dosdev is selected / tube sheet plates should have a low speed limit, to the plate was podderjivalos a certain layer of liquid, which would give the plate an opportunity to function. In normal workspace fluid sprinkling plate / tube sheet scapulae throughput through the openings of the plate to a plate, and between the plates is skipped closed gas phase separated liquid phase.

Hydraulically sealed (sealed) plates with transverse current is different from / tube sheet plates so that when they shut down the columns may not work at idle, except for a tiny hole at idle (its cross-section, usually, more than 200 times smaller than the total cross-section of the passageway areas)that the principles of expediency contains each plate with transverse current.

Thus, even at low loads columns hydraulically sealed plates with transverse current contain the accumulated liquid (the phlegm and/or feed liquid) and not in danger of drying out. This is because in the case of places of passage hydraulically sealed plates with transverse current, unlike / tube sheet plates, it is not about the holes for the exhaust gases. On the contrary, each passage ends with a pipe for exhaust gases, which prevents drying out. Above the pipe is caused to swivel cover (alpacca), immersed in the accumulated fluid plates. Often the edges of the caps have slots or teeth. Caps change the direction of the current of the rising gas stream, which then flows parallel to the plate, that is, across the columns, the accumulated liquid.

Bubbles of steam which rise from neighboring caps, which are typically located above the plate and equidistant from each other, the accumulated liquid form flowing layer.

The exhaust pipe or segments, which, as a rule, alternately to the right or left face of the plate, adjust using the valve - liquid level mass-transfer plates and serve the liquid in the lower plate. For hydraulic sealing important is the fact that the exhaust pipe or the segments of the upper plate immersed in the stored liquid under her plate. Preferably without using any valves. Adjustable caps allow you to customize the flow regimes and to equalize the height of the gates with uneven received, so all caps plates hairout the same.

Depending on the shape and location of single-threaded caps hydraulically sealed plates with transverse current is divided into plates with round caps (place of passage, a pipe for gas outlet and cap are round), tunnel t of the plate (the place of the passage, pipe for gas outlet and cap are rectangular, the caps are arranged one behind the other, with the long edge is parallel to the direction of the cross flow of liquid and plates of Thormann (place of passage, a pipe for gas outlet and cap are rectangular, the caps are arranged one behind the other, with the longest edge is perpendicular to the transverse direction of a liquid).

Under the valve in this context, see plates with transverse current, which contain holes, equipped with disc, ballast, or lifting (floating) valve restrictors, which fit the size of the access hole under the corresponding load of the column. The upward flow of gas away, it flows parallel to the plate in the accumulated phlegm and forms a flowing layer. Equipped with valves exhaust pipes direct the phlegm from plate to plate. They are often double-flow, although there may be three - and multi-threaded (for example, to cosmipolitan).

Mass transfer plates, in which there is an equilibrium between the downward flow of liquid and an ascending flow of vapor, called theoretical plates.

This concept can be transferred as all the other suitable for countercurrent distillation (rectification) built-separating elements (in the example, gaskets and packing), and other thermal separation processes, such as sorption and extraction. In the case of the latter, above the built-in separators increase the interface between the two liquid phases.

In this case, it is advisable to talk about theoretical stages of separation. Under theoretical stage of separation see unit volume, which contributes to the enrichment in accordance with thermodynamic equilibrium.

The purpose of thermal separation processes for separating at least one mass flow, enriched (meth)acrylic monomers, of a mixture containing (meth)acrylic monomers, on the one hand, is to achieve the highest degree of enrichment separated, enriched (meth)acrylic monomers of the mass flow of the monomer (meth)acrylic acid, on the other hand, the achievement of the highest outputs in terms of volume and time divided by the mass flow.

The disadvantage of the above-described thermal separation processes is the fact that those measures, which are under constant boundary conditions increase the degree of enrichment, at the same time reduce the output volume and time (for example, when the number of theoretical stages of separation, as a rule, it is possible to improve the degree of enrichment; while when permanent what s the boundary conditions to increase the number of theoretical stages of separation, as a rule, reduces the output volume and time).

The present invention is to develop a thermal separation processes fractional condensation of a mixture of the product gas obtained heterogeneous catalyzed partial oxidation in the gas phase of propene and/or propane to acrylic acid, for separating at least one mass flow of enriched acrylic acid from a mixture of the product gas containing acrylic acid, which can achieve a high degree of enrichment, while ensuring high output volume and time.

This object is achieved, we offer thermal separation by fractional condensation of a mixture of the product gas obtained heterogeneous catalyzed partial oxidation in the gas phase of propene and/or propane to acrylic acid, for separating at least one mass flow of enriched acrylic acid from a mixture of the product gas containing acrylic acid, which includes continuous stationary operation, at least one device for thermal separation, containing at least one effective separating chamber with a distillation column having a mass transfer plates as built-dividing elements, in which the mixture was charged the product of the-gas, contains acrylic acid as at least one of the mass stream containing acrylic acid, and from which discharged, at least one mass stream containing acrylic acid, provided that

- mass flow, which in General is loaded into effective separating chamber and is obtained by adding downloadable effective in separating chamber separate mass flow contains X wt.% other than (acrylic acid components

mass flow, which is discharged from the effective separating chamber with the highest weight fractions of acrylic acid, contains Y wt.% other than acrylic acid components

the ratio X:Y is ≥5,

effective separation chamber, except the place of loading and place of discharge of the stream is limited to the solid phase and contains, in addition to mass transfer plates as built-separation elements in a distillation column, at least one circulating a heat exchanger

- the total volume of the chamber filled with the liquid phase, is 1 m3, and the temperature of the liquid phase, at least partially make up ≥80°C.

When splitting an effective separating chamber into n individual volume elements, and the highest and lowest temperature within a certain volume element of the liquid phase differ by no more than 2°C, the volume element in effective separation chamber is a solid,

the total residence time ttotal

is ≤20 h,

and

A=(Ti-Tabout)/10°C

Tabout=100°C,

Ti= the average of the highest and lowest temperature of the volume element i in the liquid phase in °C,

msi= total weight of (meth)acrylic monomers contained in the liquid phase volume element i,

= total number of paged from the volume element i of the flow of liquid-phase mass

assuming that the volume elements of i contained in the liquid-phase mass miandas a three-dimensional elements with a dead zone is also little included in the sum of all volume elements i, as a volumetric elements of i that do not contain the liquid phase, and the total amount of the liquid phase contained in the three-dimensional elements with a dead zone is not more than 5 wt.% from the total amount of the liquid phase contained in the effective separation chamber.

The notion of stationary operation in this context means that the content of substances and magnitude of flow in the mass flow under steady-state operation may vary a maximum of 5% (in terms of average value is, used as a basis for comparison). According to the invention these variations are preferably ≤4%, particularly preferably ≤3% and most preferably ≤2% ≤1%.

(Meth)acrylic monomers, particularly acrylic acid, are valuable starting compounds for producing products of the polymerization are, for example, are used as adhesives.

Acrylic acid on an industrial scale is produced preferably by catalytic oxidation in the gas phase of propene and/or propane.

In this case, as a rule, receive a mixture of the product gas from which you want to separate acrylic acid.

To implement this separation, use one or more of the above-described techniques of thermal separation. They, as a rule, carried out continuously, and effectively separating chamber under constant conditions continuously load and from this chamber unloaded mass flows. Characteristic of the above-described thermal separation is the fact that the effect of separation requires a supply (for example, evaporation) and/or drain (e.g., condensation) thermal energy, as well as participate in a liquid phase (available in effective separation chamber).

Typically, this thermal energy away and/or down through the circus of the air heat exchanger. The circulation heat exchanger is part of the effective separating chamber, necessary for the implementation of the above-described method, in which serves are taken from the other side of the chamber with liquid and/or gas phase. Circulating heat exchanger to this liquid and/or gas phase is not included in the effective separating chamber source directly (for example, by inputting the source in the camera) and/or indirectly lead and/or dissipate thermal energy. Then cooled or heated liquid (which is when the heat exchange may be partially and/or completely converted into the vapour phase) and/or the gas phase (which is when the heat exchange may be partially and/or fully condensed) return to another part of the camera, and the capture and return can be spatially located separately from each other. In many cases, at least one of the circulation heat exchanger is a coolant circulation evaporating device.

The effect of thermal separation (i.e. thermal separation processes) possibly effective in separating the cells that do not contain built-dividing elements, as, for example, in the case of simple distillation. When this liquid mixture is partially evaporated, and the resulting as a consequence, the steam phase, the composition of which differs from the composition of the liquid sm is si, emit vapor and/or condensed form.

Often thermal effect of separating the reach also with built-in separation of elements, and several times served a gas (usually upward flow) and liquid (usually downward flow) flows in parallel or opposite direction. As a result, arising between threads imbalance occurs heat and mass transfer, which ultimately leads to the desired separation. As a rule, built-dividing elements are in a distillation column.

Characteristic thermal separation processes in this text is the fact that individual chemical compounds that passed through effective separating chamber, while passing through this chamber chemically changed by less than 20 mol.% (in terms of the total number of noise through the camera of individual chemical compounds, except for annexation by Michael acrylic acid; it should not be regarded as such a chemical change).

Often the interest amount in the implementation of thermal separation according to the invention are ≤10 mol.%, or ≤7 mol.%, or ≤3 mol.%, or ≤1 mol.%.

The basis of the method according to the invention is the fact that acrylic acid in the implementation odnokratno the th or multiple join Michael to form oligomers or polymers (addition products Michael), which are characterized by the General formula I

,

in which y, in particular, equal to from 1 to 6, partly also of >6.

Among other things, the scheme of formation of products of joining Michael is also known from EP-A 733617, EP-A 765861, DE-A 19536191, DE-AND 19851984, DE-A 19927722, EP-A 780360, EP-A 780359, WO 98/08798, WO 97/48669 and DE-A 19924533.

Lack of education products join Michael from (meth)acrylic monomers, in particular of acrylic acid, is the fact that education is also carried out in the framework of thermal separation methods for separating at least one mass flow, enriched (meth)acrylic monomers, of a mixture containing (meth)acrylic monomers, as the degree of enrichment and the output volume and time are reduced. The only possible solution to the problem proposed in the prior art, is the isolation and subsequent separation of the products joining Michael (see, for example, EP-A 780359, EP-A 780360, WO 98/08798 and DE-A 19924533).

When solving this problem should take into account that the formation of the products of accession by Michael from (meth)acrylic monomers is mainly only in the liquid phase.

In addition, it is necessary to consider that the formation of the products joining Michael in the liquid phase is considerably accelerated as with increasing temperature, and p and the increase of mass fraction of (meth)acrylic monomers in the liquid phase, moreover, the temperature increases by 10°C doubles the rate of reaction. At temperatures substantially below 100°With the accession of Michael acrylic monomers can be neglected.

This means that when the continuous implementation of thermal separation processes for separating at least one mass flow of enriched acrylic acid from a mixture containing acrylic acid, a stationary device, you must ensure that the stay of acrylic acid in the liquid phase was particularly short in the area of high temperature and high mass fraction of acrylic acid in the liquid phase, which can significantly reduce the disadvantageous formation of acrylic acid on Michael in the framework of thermal methods of separation.

Thus, the corresponding amount is calculated accordingly from the individual scores stay the overall average duration of stay of acrylic acid in the implementation of thermal separation processes in the liquid phase.

With this purpose, effective separating chamber is divided into n individual volume elements. The size and the number n of these volume elements, as a rule, are immaterial, that is, a single three-dimensional elements can be the same or different sizes. It is essential only that the condition that the button is the highest and the lowest temperature of the liquid phase volume element does not differ by more than 2°C, the volume element in effective separation chamber was solid (this temperature condition, as indicated below, affects the temperature dependence of joining Michael).

Thus, a separate time tiacrylic acid in a volume element i is calculated according to the formula

While mimeans the total amount of liquid mass contained in a volume element i, ameans the total number of paged from the volume element i of the flow of liquid-phase mass (in the steady state it is like loaded into the volume element i of the flow of liquid-phase mass).

In order to take into account the mass fraction of acrylic acid in volume element i, it is a separate time is multiplied by a factor of msi/mi.

Factor 2Andwhere A=(Ti-To)/10°C, further enhances the value of a particular time and takes into account the temperature in the liquid phase volume element i. Then all the volume i, containing the liquid phase, are added.

Three-dimensional elements with a dead zone i do not include in the sum, since they practically do not participate in the separation process. This applies especially to those cases whereor ≥300 h or ≥400 h or ≥500 h, or ≥750 h or ≥1000 hours

P and the implementation of the method of separation according to the invention three-dimensional elements with a dead zone is practically not involved in the process of exchange, prior to the separation. Under such volume elements involve mainly isolated three-dimensional elements, which once filled with the liquid phase and over time contain mostly the same liquid phase.

Typically, when implementing the method according to the invention avoid such bulk items with a dead zone, primarily because they imply an increased probability of a radical polymerization contained in acrylic acid.

This means that the method according to the invention is advantageous when the total amount of the liquid phase contained in the three-dimensional elements with a dead zone, less than 4 wt.%, preferably 3 wt.%, especially preferably 2 wt.% and most preferably 1 wt.% or even a trace quantities.

Furthermore, it is important for the method according to the invention is that X:Y≥5. This means that the method according to the invention does not influence negatively on the number of theoretical stages of separation, moreover, in the process according to the invention a separate time tido not take into account especially in the case when msi/miand a are high, and the refusal of tiwill not significantly affect the number of theoretical stages of separation.

Thus, the method is according to the invention is also applicable, when X:Y≥8, or ≥10 or ≥15 or ≥20 or ≥30 or ≥40 or ≥50.

Typically, X:Y in the process according to the invention does not exceed 200. In most cases, X:Y in the process according to the invention ≤175, ≤150 ≤100.

The method according to the invention is preferred when filled with the liquid phase, the total volume V of the effective separating chamber is large, for example, he is ≥2 m3or ≥4 m3, ≥5 m3or ≥7 m3or ≥9 m3, ≥10 m3or ≥15 m3. Typically, V does not exceed 500 m3. This means that in the process according to the invention V≤450 m3often ≤400 m3more often ≤350 m3in most cases ≤300 m3.

Because of the high boiling point of acrylic acid, the temperature being effective in the separation chamber of the liquid phase in the implementation of the method according to the invention is often at least partially ≥90°C or ≥100°C or ≥110°C or ≥120°C or ≥130°C or ≥140°C or ≥150°C or ≥160°C or ≥170°C or ≥180°C. However, the highest temperature in volume element i of the liquid phase in the method according the invention generally does not exceed 250°C. Typically, this higher temperature ≤230°C, often ≤210°C and most of ≤200°C. When carrying out the above reactions division, as a rule, not the Uday is camping to reach such temperatures, because these reactions provide that the separation products continuously lose its balance.

Preferably the total residence time ttotalin the process according to the invention ≤15 h or ≤10 am Particularly preferably ttotalaccording to the invention ≤8 h or ≤6 h or ≤4 hours ≤2 hours usually, ttotalin the process according to the invention ≥0.5 h or ≥1 o'clock

The method according to the invention can be used for the implementation are described in EP-A 648732 and EP-A 270999 distillation method of purification of the crude (meth)acrylic acid, described in DE-a 19924533, DE-A 10247240 and DE-A 10243625 way fractionated condensation to separate the crude acrylic acid from a mixture of the product gas obtained by partial oxidation of propene and/or propane to acrylic acid, described in EP-A 717029 way distillation of the crude (meth)acrylic acid from a mixture containing (meth)acrylic acid as a main component inert hydrophobic organic liquid with a higher boiling point than (meth)acrylic acid, described in DE-A 4308087 absorption selection of acrylic acid from the reaction gases of the catalytic partial oxidation of propene and/or acrolein, as well as for the enjoyment of other described in this application, as well as in EP-A 99063, EP-A 861820, EP-A 778255, EP-A 551111, EP-A 695736, EP-A 1026145, DE-A 10251328 and/or cited in other literature sources distillation, sorption and/or extractive thermal separation methods for selecting at least one mass flow, enriched (meth)acrylic monomers, of a mixture containing (meth)acrylic monomers.

Often, when implementing the above methods and method according to the invention effective separation column includes at least one coolant heat exchanger and at least one column with or without built-dividing elements.

Because absorption separation usually occurs with evolution of heat, at least one of the heat exchangers performs the function of heat dissipation. This is implemented by an indirect method using a cooling fluid (refrigerant), which never enters the effective separating chamber, this means that only one of the two chamber walls of the heat exchanger is an integral part of the effective separating chamber. The other is outside and brings the refrigerant. Flow mass flow to the wall of the heat exchanger, which is owned by the effective separation chamber, is carried out, as a rule, using at least one pump.

When making big if is esta thermal separation other than absorption, heat lead to effective separation chamber through the circulation heat exchanger. In most cases, this also happens in an indirect way by using a refrigerant that never enters the effective separating chamber. In other words, only one of the two chamber walls of the heat exchanger is an integral part of the effective separating chamber. The other is outside and brings the coolant. Often served as much heat in the wall of the heat exchanger, owned by the effective separation chamber, there is the effect of boiling.

In this case, the circulation heat exchanger is called the circulation of the evaporating apparatus. Flow mass flow to the wall of the heat exchanger, which is owned by the effective separation chamber, can be done by using a pump (forced circulation) and/or by natural circulation (the latter due to the difference in mass density occurs between the heated and unheated mass flow).

As the circulation heat exchanger uses coolant circulation evaporating device, especially if thermal separation processes according to the invention involve rectification.

Basically, in the method according to the invention as an indirect circulation heat exchangers can be used is Ana all known types of indirect heat exchangers. Preferably they are chosen so that the volume of the liquid phase in them was minimal.

If circulation evaporator is used, for example, integrated in a distillation column the evaporators Robert (the evaporators with natural circulation), as depicted in figure 1 (1 - distillation column, 2 - steam cogeneration selection, 3 - steam condensate heat selection, 4 - unloading cube, 5 - fluid level, 6 - evaporative pipe, 7 - Central return pipe 8 in the direction of circulation).

In addition, as the circulation evaporator can be used derived from a distillation column evaporation apparatus with forced circulation shown in figure 2 (1 - distillation column, 2 - pump, 3 - tubular evaporating device, 4 - steam cogeneration selection, 5 - condensate of the heating steam 6 - unloading cubic product, 7 - direction of rotation (circulation), 8 - separation device, 9 - outflow, 10 - inflow, 11 - fluid level).

Of course, as the circulation evaporator can also be used reducing evaporation apparatus with forced circulation, which is schematically shown in figure 3 (1 - distillation column, 2 - pump, 3 - throttling device, 4 - tube is Epernay apparatus, 5 - cogeneration steam, 6 - condensate heating steam, 7 - unloading cubic product, 8 - direction of circulation, 9 - separation device, 10 - outflow, 11 - inflow, 12 - fluid level). Reducing evaporation apparatus with forced circulation in contrast to the evaporator with forced circulation is separated from the distillation column in a throttling device. Continuously take part of the liquid contents of the distillation column under pressure Pxand by means of the circulation pump into the tributaries of the tubular evaporator (shell and tube heat exchanger). Internal pipes of the tubular evaporator the heat transfer medium flows, for example district heating steam (typically under pressure of water vapor), the temperature above the liquid environment of the distillation column. Passing through inlet and outlet tubes of the tubular evaporator discharged from the distillation column a liquid by indirect heat exchange heated to a temperature Tythat is higher than the temperature of liquid of the distillation column.

Throttling device divides the tubular evaporator apparatus and distillation column and allows by varying the capacity of the circulation pump to install in excess of Rxsource giving is giving a throttling device P ythat is higher than the corresponding temperature Ty'boiling pressure Py'discharged from the distillation column of liquid. The above methods are able to suppress the boiling liquid fraction, pumped from the distillation column in pipe tubular evaporator. The fluid pumped from the distillation column in pipe tubular evaporator, significantly overheat compared to the existing in the liquid environment of the distillation column pressure Pxthus the process of boiling is moved toward passage throttling device (in other words, the contents of the tubes of the tubular evaporator is single-phase, tubular evaporating device operates only as a superheater). The release of the hot fluid through the throttling device in the distillation column can be made directly in the liquid contents of the distillation column (rectifying column bottom). Under such conditions, the temperature of the liquid contents of the cube distillation columns typically corresponds to the boiling temperature of Txat a pressure Pxon bottom of the liquid.

Typically, the release of the hot fluid through the throttling device in the distillation column above the liquid level of the cube of the distillation column. Pricacy conditions, the temperature of the liquid contents of the cube of the distillation column is typically below the boiling temperature T xat a pressure Pxon bottom of the liquid. Important is the fact that the effect of boiling outside the distillation column tube evaporator first occurs in a distillation column, that is, outside the circulation evaporator. When this throttling can, for example, to carry out mechanically (jumpers, valves) and/or hydrostatically (using the corresponding high columns over the place of the passage of the hot liquid).

As the circulation evaporator can also be used evaporating device with direct circulation, as he, for example, depicted in figure 4, which serves obtained outside the effective separating chamber fluid and subjected to direct contact with the subject to evaporation of the liquid.

From cube 9 distillation column 8 unload the fluid and/or use located in the lower part of the distillation column team plates 1 unload the high-boiling fraction. Then one or both of discharged liquid is sprayed into the evaporation apparatus with a direct circulation 6, in which, for example, are mixed in a parallel stream having a higher temperature with a mixture of the product gas 2 received partial oxidation of propene and/or propane, as a direct coolant and subjected to direct t is loobman, thus, at least partially vaporizing. Then the whole mixture of 10 returned to the rectifying column bottom liquid (the return can also be performed without immersion), and ascending as a result, the flow of the gas mixture is subjected to fractionation condensation. The flow discharged from the distillation column of liquid is carried out using pumps 4, 5. Under positional designation 3 mean discharge cubic product, and under 7 - the bottom level of the liquid. Evaporating device with direct circulation, as a rule, does not contain built-dividing elements, and has a cylindrical shape. Gas and liquid phase can also be separately discharged from the evaporator with a direct circulation in the distillation column. Such evaporation apparatus with a direct circulation is shown schematically in figure 5. Reference designators have the same values as in figure 4.

10A means returned to the distillation column gas phase and 10b is returned to the distillation column a liquid phase. 11 indicates the liquid level in the evaporating apparatus with direct circulation.

Distillation column may not contain or may contain embedded separators, and for implementing the method according to the invention suitable are all mentioned in this application is built dividing ELEH the coefficients separately or if necessary, in combination with other built-dividing elements.

The bulk of nozzles used, for example, glass ring process, the nozzle in the form of saddles, nozzles in the form of wire meshes, V2A-spirals, rings Palla and capsules of Stedman, and nozzles of the second, third and fourth generation.

As nozzles, the diameter of which is almost equal to the inner diameter of the column, use gaskets of different species. It usually goes on permeable three-dimensional metal, plastic and/or ceramic meshes with a large surface area.

If the implementation of thermal separation processes according to the invention it comes to fractionation condensation of a mixture gas obtained by one - or two-stage heterogeneous catalyzed oxidation of propene and/or propane to acrylic acid distillation column as built-dividing elements, preferably bottom-up contains the first double-flow plates, and then hydraulically sealed plates with transverse current (for example, plates Thormann®, or modified plates of Tormann), as described in DE-a 19924532, DE-A 10243625 and DE-A 10247240.

The number of theoretical stages of separation is from 15 to 30, preferably 20. Evaporating apparatus I which is above the evaporation apparatus with a direct circulation. If the condensation column integrated another carbon dioxide refrigerant in the condensing zone of the column as built-dividing elements, preferably using the valve plate, is described in DE-A 19924532, DE-A 10243625 and DE-A 10247240.

According to the General formula for ttotalin the process according to the invention the values of ttotalare insignificant in the case, if large values ofare possibly small. In other words, set according to the invention the objective can be achieved, inter alia, by reducing the total number in the separation chamber in stationone condition of the liquid phase at relatively the same performance mass flow and theoretical stages of separation, which is preferably carried out in those three-dimensional elements, in which the liquid phase has a higher temperature and a decrease of the liquid phase in which will not entail reducing the number of theoretical stages. Primarily for this purpose, use the following options. The first possibility is to reduce the cross section of the pipe effectively separating chamber through which pass the liquid phase containing acrylic acid, due to the imminent pteridine at the same volumetric flow), as well as reducing the length of the pipe.

In the case of the above-described fractionation condensation in the framework of the present invention preference is given to the way in which no other circulation heat exchanger, in addition to the evaporator with direct circulation, does not belong effective separation chamber.

Thus, in contrast to figure 1 and figure 2 DE-A 19924533 or Fig. DE-AND 19924532, and in contrast to DE-A 10247240 according to the invention advantageously completely abandon the circulation heat exchanger 8 of the above-mentioned figures and to use only the heat of vaporization of a mixture of the product gas obtained by partial oxidation of propene and/or propane to acrylic acid. Thus evaporating device with direct circulation according to the invention preferably has shown in figure 4, and not 5 structure, in which a mixture of gas and liquid as a two-phase system is fed directly to a distillation column, resulting in contrast, the method according to figure 5 it is possible to avoid occurrence of an additional level of liquid increases as a separate time). At the same time reduce the cross-section of the evaporator with a direct circulation at a constant circulation quantities (simultaneously evaporating device with direct circulation is also a direct cooler DL is a mixture of the product gas, the resulting partial oxidation; to maintain the heat balance of the circulation number should be kept to a minimum) in order to reduce the amount of liquid phase in the effective separation chamber.

If the effective separating chamber as built-dividing elements includes mass transfer plates, as such according to the invention preferably use / tube sheet plates, particularly preferably sprinkler plate / tube sheet (twin plate). Since the latter do not contain any overflow valves, they are used especially when a low liquid level, when compared with hydraulically sealed plates with transverse shock, they according to the invention are preferred. The latter is used only if received through sprinkler / tube sheet plates the effect of separation is insufficient.

If the effective separation chamber contains prefabricated plates (for example, as a component of a distillation column), through which, for example, unload the separated liquid mass flow of the effective separating chamber (for example, in a settling tank or circulating a heat exchanger, according to the invention is used in most low fluid level. It is possible, for example, by drawing on teams tar the CTL of the displacers. They allow increasing the level of the liquid at a reduced volume. Alternative solution offers DE-10159825 in the form of prefabricated plates with a difference.

In the process according to the invention corresponding plungers were preferred also for segments of the cube (cube cameras) distillation columns. They usually are the components of the camera, which geometrically are built under the lower separating elements. In the case of rectification as thermal separation processes according to the invention of the segments Cuba regularly unload cubic liquid and serve it in a heat exchanger with forced circulation. At the same time, waste liquid, as a rule, is in a state of boiling.

In order to avoid that the pump is required to force-feed substances in the heat exchanger with forced circulation, for example, in case of violation mode is pumping too much gas (which typically reduces the pump power and can in the worst case cause its destruction, since the pump is usually used to pump fluid), in the segment of the cube establish a safe level of the liquid.

This safe level according to the invention in a reduced volume of a cube reach preferred by drawing on the camera cube displacers is whether by isolating the camera cube as shown in Fig.6. Of course, in the method according to the invention can be implemented reducing the volume of the cube.

According to the invention the reduction of the volume of the cube is preferred in each case compared with the solutions proposed in Fig.7, where between the pump and the cube columns for safety reasons, provided the buffer vessel to the bottom of the liquid. Used in the method according to the invention, the pumps are chosen so that they are kept as low as possible amount of liquid phase.

Temperature Tiin the process according to the invention it is possible to define a simple experimental method (e.g., by using appropriately placed thermocouples).

As a rule, the choice of the volume element i in the method according to the invention is arbitrary, it almost does not affect the result for ttotal. However, in many cases are the most beneficial options bulk items i.

In the case of mass transfer plates with forced submission as a volume element i use such a dimensional element, which takes into account the level of liquid mass transfer plate and the flow of fluid to below the mass transfer plate, as is schematically illustrated Fig using shaded area. 1 means the place of a tributary to about the roadways to the element, 2 - place the outflow from the volume element, 3 - relief valve, 4 - wall columns and 5 means mass transfer plate having passages (6 - fluid level in the drain or receiving mine).

msidefine, for example, thus: the current location of inflow and outflow at the same time close, and then define a contained volume element i of the weight of the liquid phase mi. Through chemical analysis of the contents of miwhat msi.define, for example, thus: drain charge embed catching plate, from which discharged the same fluid flow rectifying column, analyze, and then return below the outflow drain charge (see Fig.9; 1 - wall column; 2 - the drain pipe; 3 - absorbing plate; 4 - pressure pump; 5 - flow measurement). In addition,you can define, whereasby downloading through the site flow indicator and its discharge through the place of outflow after a certain period of time. The latter, for example, can be done through continuous selection of a small sample in location 7 on Fig. The place of unloading of the indicator, as a rule, is the place on 8 Fig.

In the case of sprinkler / tube sheet plates can act accordingly. The quality of the ve volume element i choose this volume element, which registers the level of liquid mass transfer plate and the space under mass-transfer plate before starting the surface of the liquid level following mass transfer plates.

In this case, to determineabove the plate / tube sheet set catching plate. From her unload the existing fluid, analyze the appropriate thread, after which it return directly above the plate / tube sheet (see figure 10; 1 - plate / tube sheet; 2 - absorbing plate; 3 - pressure pump; 4 - flow measurement).

Located on the sprinkler plate / tube sheet amount of fluid can also be analyzed using differential pressure measurement according to 11 (method a U-shaped gauge). This Δ=ς·g·hL(hL- 1 figure 11), where ς denotes the mass density of the liquid phase, g denotes the gravitational constant, a hLmeans the level of the liquid phase on the sprinkler plate / tube sheet, you can directly read hLand calculate the amount of fluid to the sprinkler plate / tube sheet.

The amount of liquid between the two sprinkler / tube sheet plates can be determined by simultaneous closing of both plates and determine the amount of liquid gathered on the bottom plate. As a result of chemical analysis of miwhat are square m si.

In accordance with this msiin Cuba the column count from the bottom level of the fluid defined by means of the outflow, as well as by analysis of the composition of the bottom liquidin a cube with a fixed liquid level determined directly by measurements. The same applies to the circulating pump, circulating heat exchanger can be processed in a similar manner. Plots of the column containing granular nozzles or fillers, can be treated in a similar way and three-dimensional elements of mass transfer plates.

Inside of the distillation column values msiand mican also be defined such semiempirical methods (see, for example, Johann Stichlmair; Grundlagen der Dimensionierung des Gas/Flüssigkeit-Kontaktapparates, Bodenkolonne, Verlag Chemie (1978) and Technische Fortschrittsberichte, Bd. 61, Grundlagen der Dimensionierung von Kolonnenböden, von Dr.-lng. Klaus Hoppe und Dr.-lng. Manfred Mittelstrass, Magdeburg, Verlag Theodor Steinkopff, Dresden (1967)).

To this end, first determine, for example, the appropriate temperature of different mass transfer plates. Then determine the composition of inflows and outflows of the distillation column. Then using the law of Raul (the equilibrium vapor and liquid) and a mass balance and energy calculate the concentration distribution in the column and get the necessary rate of flow of liquid and gas. The index msiop is edalat thus: first, when conducting individual tests (bottom serves gas, and on top of wash liquid) determine the hydrodynamic properties of the built-separation of elements, for example, mass transfer plates, and then to get the indices mion the basis of which the distribution concentration obtained indices msi.

Unexpected in the process according to the invention was the fact that by decreasing values of ttotalunder constant boundary conditions it is possible to improve the output by time and volume, and the degree of enrichment.

As shown below in the example implementation, the method according to the invention when the value of ttotal≤10 h allows to separate the crude acrylic acid, the content of the fraction of acrylic acid in which ≥95 wt.%, from a mixture of the product gas obtained by one - or two-stage heterogeneous catalyzed partial oxidation of propene and/or propane to acrylic acid, the content of the fraction of acrylic acid which comprises from 5 to 15 wt.%.

thermal separation processes include continuous stationary operation of the device for thermal separation, containing an effective separating chamber with built-dividing elements, which is schematically illustrated Fig.

The camera consists of a distillation column 28 (which as built section is sustained fashion elements contains only mass transfer plates; underneath imply posted by bottom-up double-flow plates, and then hydraulically sealed plates with transverse current, separated the valve; optional rectifying column contains prefabricated plates)that do not contain built-in separation elements evaporator with direct circulation 1, carried out with the help of the pump 7 and the pump 29, and the pipes 6, 6', 3, 3' and 2. More details such separation column is described in DE-a 19924532, DE-A 10247240 and DE-A 10243625. The number of theoretical stages of separation, usually ranging from 15 to 30, preferably 20. All elements of this effective separation chamber can be used as components of an applied device for thermal separation, however, they are not included in the composition used according to the invention effectively separating chamber. Its expansion increases the value of ttotaland does not contribute to thermal separation. The method according to the invention is used primarily in the case when the applied thermal method of separation involves the method according to the invention. Subject to separation of a mixture of the product gas obtained by one - or two-stage heterogeneous catalyzed partial oxidation of propene and/or propane to acrylic acid, at the same time is a direct source t the PLA for evaporating element with direct circulation.

The following example and comparative example to explain the invention without limiting its obscuripennis. In obtained by carrying out the method according to the invention the liquid phase, which contain acrylic acid, known methods add polymerization inhibitors.

The example and the comparative example (digital indicators relate to Fig; grey shaded area on Fig means considered effective separating chamber)

Comparative example (described stationary state; a suitable material is, for example, stainless steel grades 1.4539 or 1.4571)

By heterogeneous catalyzed partial oxidation in the gas phase propylene purity "polymer grade" get having a temperature of 270°C. a mixture of the product gas of the following composition:

11,80% wt. acrylic acid,

0,264 wt.% acetic acid,

5,0984 wt.% water,

0,0275 wt.% formic acid,

0,0989 wt.% formaldehyde,

0,1473 wt.% acrolein,

0,0028% wt. propionic acid,

0,0033% wt. furfural,

0,0014% wt. allylacetate,

of 0.0005 wt.% alifornia,

0,0038% wt. benzaldehyde,

0,1350 wt.% maleic anhydride,

0,0112 wt.% benzoic acid,

0,0147 wt.% phthalic anhydride,

4,0324 wt.% oxygen

1,8067 wt.% carbon dioxide

0,5904 wt.% carbon monoxide,

0,5520 wt.%propane,

0,2696 wt.% propylene and

75,1399 wt.% of nitrogen.

Other components were not found. A mixture of the product gas (170008 kg/h) heat exchanger with direct circulation 1 and DC is cooled to a temperature 120,2°C. the heat Exchanger with direct circulation 1 and DC does not contain inline elements. He has a cylindrical shape. Its diameter is 2.2 m and a height of 15.5 m in the Liquid phase, to be heated in the heat exchanger with direct circulation 1, the mixture is discharged from the chamber 5 cube bottom liquid and trudnoca faction, which was unloaded from the first detecting plate 10, adjacent to the chamber 5 cube distillation column 28.

The amount supplied to the heat exchanger with direct circulation 1 bottom liquid is 247305 kg/h, it has such a composition (mass density = 989,22 kg/m3):

27,2977 wt.% acrylic acid,

0,1446 wt.% acetic acid,

0,6007 wt.% water,

0,0069 wt.% formic acid,

0,0007% wt. formaldehyde,

0,0087% wt. acrolein,

0,0149 wt.% propionic acid,

0,2041 wt.% furfural,

0,0008% wt. allylacetate,

0.0001 wt.% alifornia,

0,2490 wt.% benzaldehyde,

4,4377 wt.% maleic anhydride,

0,7354 wt.% benzoic acid,

0,9605 wt.% phthalic anhydride,

19,5513 wt.%diacrylates acid,

40,1375 wt.% polyacrylic acid (product connected is inane Michael),

0,4855 wt.% fenotiazina,

0,5560 wt.% nanometrology ether of hydroquinone (MEHQ),

4,6079 wt.% other high-boiling components and

is 0.0002 wt.% the oxygen.

The temperature of the bottom liquid is 118,3°C, the vapor pressure is 1.48 bar. The amount supplied to the heat exchanger with direct circulation 1 trudnoca fraction 63009 kg/h, it has such a composition (mass density = 969,94 kg/m3):

90,4867 wt.% acrylic acid,

0,3672 wt.% acetic acid,

1,4207 wt.% water,

0,0142 wt.% formic acid,

0,0016% wt. formaldehyde,

0,0109 wt.% acrolein,

0,0535 wt.% propionic acid,

0,6232 wt.% furfural,

0,0025% wt. allylacetate,

is 0.0002 wt.% alifornia,

0,5317 wt.% benzaldehyde,

4,9046 wt.% maleic anhydride,

0,0401 wt.% benzoic acid,

0,0344 wt.% phthalic anhydride,

1,4102 wt.% diacrylates acid,

0,0201 wt.% fenotiazina,

0,0779 wt.% Q and

of 0.0004 wt.% the oxygen.

The temperature of the high-boiling fraction was 100.4°C, the vapor pressure is 1.48 bar.

Supply high-boiling fraction in the heat exchanger (evaporator unit) with direct circulation exercise 1 via line 3 with a diameter of 150 mm and a length of 10 m in the direction of the centrifugal pump 29 (capacity liquid: 50 l) and thence through the pipe 3' diameter 150 mm and length 15 m - evaporating device with direct circulation 1 (Altern the effective high-boiling fraction through the relief valve to supply the camera cube and as an integral part of the bottom liquid load in the evaporator apparatus with direct circulation).

Cubic liquid discharged from the chamber 5 of the cube, the number 249905 kg/h through the pipe 6 with a diameter of 300 mm and a length of 10 in the direction of the centrifugal pump 7 (capacity liquid: 100 l) and from there to the number 247305 kg/h through the pipe 6' length of 10 m and a diameter of 300 mm (for pipe diameter in this context, see inner diameter) - evaporating device with direct circulation 1. 2300 kg/h unloaded the bottom of the liquid serves to separate and 300 kg/h unloaded the bottom of the liquid serves to conduct the following cooling cycle I in order to prevent undesired polymerization (in both cases, the flow passes through the piping 8). A mixture of bottom liquid and the high-boiling fraction by means of the nozzle (tip sprayer with a reflector according to WO 02/50011) is sprayed into the evaporation apparatus with a direct circulation 1.

Discharged from the evaporator with a direct circulation 1 two-phase mixture having a temperature 120,2°C, through a pipeline 2 (diameter: 1500 mm; length: 10 m) return into the chamber 5 of the cube.

The pressure in the chamber 5 of the cube and in the evaporation apparatus with a direct circulation 1 is 1,48 bar. The height of the distillation column 28 (columns for fractional condensation, which as built effective separation of elements contains only mass transfer plates; under them understand posted by bottom-up double-flow plates, and then hydraulically sealed plates with transverse current (a plate of Tormann), separated the valve) is 54,3 m

The inner diameter of the distillation column 28 in the area of the plates of Tormann is 6.5 m, and the rest part - 6,0 m

A device for the separation (which, for example, does not belong effective separation chamber), which serves 2300 kg/h unloaded from the chamber 5 cube bottom liquid, consists of reducing evaporator with forced circulation and placed it in a seamless way of a twin plates of the distillation column. The number of plates is 50.

Reducing evaporation apparatus with forced circulation consists of copper for separation, heat exchanger, pump and related piping. Discharged from the boiler substances through the tubing serves to centrifugal pump, which loads them into a tube and shell heat exchanger. Then a portion of the heated liquid through the pipe back to the boiler, and the other part of the heated fluid, determining its viscosity, density, or temperature, served in the following tank, to which is added methanol.

As distillation column 28, this distillation column are isolated from the external environment. The inner diameter of the distillation column, including all dvukhfotonnymi, is 2.4 m, its height is 27 m double-flow plates in a distillation column equidistant from each other (400 mm). Their relative aperture is 12%. Looking upwards, the diameter of the holes of the first eight double-flow plates 25 mm (the location of the holes clearly corresponds to the triangular sectors), and the diameter of all other double-flow plates is 14 mm (the location of the holes clearly corresponds to the triangular sectors). Cubic liquid to be split, served on eight double-flow plates (below).

In the tank for separating the reducing evaporator with forced circulation serves 20000 kg/h later superheated and compressed circulating gas discharged from the head of the condensation column (as an auxiliary gas) (pressure = 2,9 bar; temperature = 160°C).

The composition of the circulating gas:

0,2288 wt.% acrylic acid,

0,0885 wt.% acetic acid,

2,6689 wt.% water,

0,0052% wt. formic acid,

0,1724 wt.% acrolein,

is 0.0002 wt.% propionic acid,

0,0003% wt. furfural.

0,0012% wt. alifornia,

4,7392 wt.% oxygen

2,1235 wt.% carbon dioxide

0,6939 wt.% carbon monoxide,

0,6487 wt.% propane,

0,3169 wt.% propylene and

88,3123 wt.% of nitrogen.

From the tank to separate vol reducing the apparatus with forced circulation constantly unload 522963 kg/h of a liquid phase, having a temperature of 161°C. and a pressure 1,71 bar, from which 522246 kg/h return to the tank for separation after passage through the heat exchanger at a temperature of 166°C. and a pressure of 3 bar. The remaining 717 kg/h Tegaserod, diluted with methanol, the precipitate burn.

Formed in the tank for separating the cracking gases with the help of auxiliary circulating gas is served in a distillation column, where they rise in an upward flow of the recirculating liquid.

From the head of the distillation column in the number 33129 kg/h unloaded mixture (consisting of the circulating gas and the cracking-gas), temperature is 99.8°C and a pressure of 1.60 bar, by direct cooling is cooled in the spray cooler with direct current (cooling cycle I) to a temperature 63,3°C and cast partial condensation.

Remaining after cooling, the mixture gas in the number 21883 kg/h, having the following composition, through line 9 returns into the chamber 5 Cuba 5 of the condensation column 28 (without immersion):

8,7215 wt.% acrylic acid,

0,0976 wt.% acetic acid,

2,5067 wt.% water,

0,0056% wt. formic acid,

0.0001 wt.% formaldehyde,

0,1584 wt.% acrolein,

0,0019% wt. propionic acid,

0,0017% wt. furfural,

0.0001 wt.% allylacetate,

0,0011% wt. alifornia,

of 0.0004 wt.% benzaldehyde,

0,0039 wt.% Malinov the th anhydride,

4,3313 wt.% oxygen

1,9407 wt.% carbon dioxide

0,6342 wt.% carbon monoxide,

0,5929 wt.% propane,

0,2896 wt.% propylene and

80,7122 wt.% of nitrogen.

As the coolant I use a mixture of 300 kg/h bottom liquid discharged from the chamber 5 of the cube, and the condensate formed in direct cooling cycle cooling I. 104207 kg/h of this mixture by indirect cooling is cooled to 32°C and sprayed in the spray cooler I cycle I. 11546 kg/h of the same mixture at a temperature 63,3°C as the recirculating fluid return to top double-flow plates placed in the tank for the separation of the distillation column.

The coolant I has the following structure:

93,7485 wt.% acrylic acid,

0,4937 wt.% acetic acid,

3,7513 wt.% water,

0,0143 wt.% formic acid,

0,0328 wt.% acrolein,

0,0207 wt.% propionic acid,

0,0240 wt.% furfural,

of 0.0005 wt.% allylacetate,

0,0017% wt. alifornia,

0,0099 wt.% benzaldehyde,

0,1591 wt.% maleic anhydride,

0,0192 wt.% benzoic acid,

0,0250 wt.% phthalic anhydride,

0,5083 wt.% diacrylates acid,

1,0429 wt.% polyacrylic acid,

0,0126 wt.% fenotiazina,

0,0146 Bec.% MEHQ,

0,1198 wt.% other high-boiling components and

0,0011% wt. the oxygen.

In the chamber 5 cube condensation colon is s 28 integrated centrifugal droplet separator, which prevents a drop bottom liquid from the camera to the cube went up. At the lower end of the chamber 5 cube has the so-called "China cap" for better separation of gas/liquid. The holding capacity of the liquid phase in the system camera 5 cube from the pipe 6 to the circulation pump 7, the circulating pump 7, line 6' of the circulation pump 7 to the evaporator with a direct circulation 1, evaporator with direct circulation 1 and pipeline 2 evaporator with direct circulation 1 in the chamber 5 of the cube is 80 m3.

The camera cube distillation column 28, as mentioned above, the height of the column 7.80 m (as well as any other height, measured from the base of the cube) is closed by means of a first detecting plate 10 (the national dish, a plate, with 16 equidistant pipes for exhaust gases; pipe diameter: 600 mm; height of tube: 1 m).

Team plate 10 has a double wall with 2 pockets inside, a Central drain Cup and the drain pipe (DN~200). The living section of the gas is approximately 30%.

From this first catching plates, as described above, unload 63009 kg/h of liquid (T=100,4°C, p=1,48 bar) and using a centrifugal pump 29 is loaded into the evaporation apparatus with a direct circulation 1. The volume of the liquid catching plate 10 is 2 m3(hold the covering ability of the system fluid volume liquid catching plate 10, from pipe 3 to the circulation pump 29, the circulation pump 29 and line 3' of the circulation pump 29 to the evaporator with a direct circulation 1 is 3 m3).

Through 2.0 m above the first detecting plate 10 is first (11) of the next 15 equidistant from each other twin plates (hole diameter 14 mm, number of holes 33678, relative aperture 18%), while the distance between the plates is 380 mm access holes are round holes with a diameter of 14 mm, with their edges in a distillation column indicates down. The locations of the access holes clearly corresponds to the triangular sectors.

Fifteenth two plate (12) is designed as a distribution plate. To this end over it caused two removable pipe (DN~150), each of which contains 40 exhaust holes (diameter: 15 mm).

The first series of twin plates closed according to WO 03 047714 using the second capture plates 14 (combined plate, a plate with 16 equidistant pipes for exhaust gases; height pipe approximately 1.70 m, Central drain Cup and the drain pipes (DN~250), the living section of the gas is approximately 30%), which is positioned at 1.50 m above the last two-line plate.

From this second capture plates 14 through drobopro is 15 at a pressure of 1.47 bar continuously unload the crude acrylic acid, having a temperature 101,2°C (mass density = 956,99 kg/m3and the following composition:

96,8011 wt.% acrylic acid,

0,4598 wt.% acetic acid,

1,4762 wt.% water,

0,0137 wt.% formic acid,

0,0015% wt. formaldehyde,

0,0087% wt. acrolein,

0,0647 wt.% propionic acid,

0,2856 wt.% furfural,

0,0027% wt. allylacetate,

is 0.0002 wt.% alifornia,

0,0744 wt.% benzaldehyde,

0,2381 wt.% maleic anhydride,

0,5430 wt.% diacrylates acid,

0,0120% wt. fenotiazina,

0,0180 wt.% Q and

of 0.0004 wt.% the oxygen.

The volume of liquid in the second catching plate 14 is 10 m3. 455855 kg/h unloaded from the second capture plates 14 of the crude acrylic acid by indirect heat exchange heat up of 111.2°C and through the return conduit 30 in the condensation column 28 directly beneath adjacent to the second catching plate going up a two-line plate 16 (p=1,50 bar).

89978 kg/h unloaded from the second capture plates of the crude acrylic acid forms a mass stream containing (meth)acrylic monomers, split effective in the separation chamber, the acid in multiple stages by indirect heat exchange (preferably with a distillation column 28 to be returning the mother liquor) is cooled to temperature the tours 29°C. Then chilled in the crude acrylic acid is added 1144 kg/h of water (25°C). The resulting mixture again by indirect heat exchange cooled to a temperature of 20°C and then serves 2-3 mold with cooling.

When it comes to the working chamber, which is provided 20-24 hanging each other round cooling plate (which is located inside the cooling medium (a mixture of water and glycol; glycol content = from 10 to 50 wt.%, preferably from 25 to 35 wt.%)), equidistant from each other at a distance of from 20 to 40 cm (the diameter of the plate is from 2 to 4 m, preferably from 2.5 to 3 m). While the cooling fluid counterflow relative to be cooled mixture is passed through the mold from the plate to the plate. In addition, it can be divided into 2 or 3 parallel flow and serve over the cooling plates. The temperature of the cooling medium at the inlet (brine) is from -2 to +5°C, outlet temperature at 2-7°C higher. Using cleaning cooling plates manages to avoid the formation of a crystalline layer. Diluted with water, the crude acrylic acid back forward continuously passed through the mold (pumped by pump or poured by means of valves). When this phase is diluted with water, the crude acrylic acid is concentrated (the time of receiving the Oia from 0.5 to 4 h, preferably from 1.5 to 2.5 h), and is formed of a two-phase suspension in which the solid phase contains crystals of acrylic acid having a temperature of from 6 to 11°C and the solid content at the outlet from 20 to 35 wt.%. The rotational speed of the wipers is from 2 to 15 rotations per minute, preferably from 4 to 10 revolutions per minute. The shaft driving cleaners, held in the center of the mold with cooling, covered rinsed with water sealing gaskets (thread gaskets made of Teflon or graphite).

The reach of cleaners locations marked (for example, Navarin) concave profile (for example, according to the most simple form of the trumpet), heated (to a temperature above the crystallization temperature; often to a temperature of from 8 to 20°C, preferably from 10 to 14°C) using a second fluid (for example, a mixture of water/glycol).

In addition, the cleaners in the radial direction is preferably divided into segments (usually ≥2, ≥6 segments). Specific power pressure cleaners in the embedded condition perpendicular to the cooling surface is from 1 to 10, preferably from 3 to 5 H in cm active length of the purifier. In addition to cleaners shaft results in movement of the blade (between the two plates, and before the first and last plates symmetrically located the school two), which promote better mixing.

Surface properties of the cooling plates and the location of the cleaners cause the fact that the distance between the cleaner and the surface of the cooling plate never exceeds 6 mm (preferably the distance should not exceed 4, 2 or 1 mm or adjacent to each point; especially preferably attached on the outer radius).

In the rear part of the mold (preferably in the last cooling plate) suspension in a closed tube (preferably by immersion; alternatively, the suspension can flow through relief valve in the collection from which it is loaded into the wash column) served in the hydraulic wash column, described in DE-A 10156016 and DE-A 10223058, with the purpose of allocation of suspension kristalliset the mother liquor. Download the wash column suspension crystallization carried out using centrifugal or rotary piston pump. The pump control current as centrifugal or rotary piston pump, equipped with a regulating valve. The pressure at the bottom of the wash column, usually ≥100 mbar and at ≤5 bar lower than the pressure at the column head. The pressure head of the column, usually up to 6 bar, frequently from 0.5 to 4 bar. Speed meter >0 and ≤100/min or ≥60/min Temperature cycle is Lavinia, as a rule, is from 13 to 16°C. the Determination of the filtration front carried out according to DE-A 10036880 with 2-4 optical sensors. Wash the front regulate temperature measurement in the crystalline layer.

The total height of the crystalline layer typically ranges from 300 to 1500 mm, frequently from 400 to 1000 mm Wash front is usually located at a height of from 10 to 400 mm, frequently from 20 to 250 mm above the meter. As the pump uses centrifugal pump, which washes the gasket shaft (contact seal) or pump with magnet, which washes the slide bearing. The amount of the substance undergoing the cycle of melting varies from 2 to 30, usually from 5 to 20 m3/h per ton analyzed by measuring the pure kristalliset. The stabilization loop fusion is performed using 100-300 weight.-M.Ch. MEHQ. Additionally, in this cycle serves the air, over which (=not dissolved in the melt fraction) unloaded before loading of the melt in the wash column through the degassing device.

[(a) To obtain capable of esterification of acrylic acid sufficient to carry out the separation of the suspension kristalliset in fuse-washing column using a centrifuge (e.g., 2 - or 3-speed centrifuge with a buoyancy device). The appropriate mesh size sieve ranges from 150 to 300 mm; used the centrifugal acceleration is from 500 to 900 g, more from 600 to 800 g; suitable number of moves ranging from 40 to 80 shifts/min

The crystals are separated preferably by 2 or 3-speed centrifuge, washed with 0.15 to 0.3 kg of washing liquid per kg of kristalliset. The liquid temperature is from 15 to 30°C, preferably from 20 to 30°C. In order to avoid sediment discharge mine for solids washed heated to 15-30°With a wash liquid. Leaching and washing liquid preferably receive from molten separated by centrifuge and washed kristalliset. In order to avoid deposition and formation of the crystalline crust of the centrifuge housing, suspension inlet pipe and the pipe that supplies the washing liquid is heated to temperatures ≥15°C and ≤40°C. the Central chamber of the centrifuge inertizing nitrogen or a mixture of air and nitrogen. The shaft seal is washed gas (e.g. nitrogen or a mixture of air and nitrogen or water;

(b) as an alternative to suspension crystallization can be carried out layer crystallization (for example, film crystallization according to EP-A 616998 or fully streamlined trumpet), including 3 or more (for example, from 3 to 4) stages of purification. Instead of returning the mother liquor and subsequent purification stages in the previous purification step can return in the condensation column.]

Of cycles of melting, stable and by the use of 3 kg/h MEHQ, get 18538 kg/h of crude acrylic acid of the following composition:

99,8335 wt.% acrylic acid,

0,0970 wt.% acetic acid,

0,0334 wt.% water,

0,0206 wt.% propionic acid,

0.0001 wt.% furfural,

0.0001 wt.% maleic anhydride,

0,0003% wt. diacrylates acid and

0,0150% wt. MEHQ.

They are particularly advantageously can be used to produce absorbent substances on the basis of poly-Pas-acrylate.

In 829 kg/h of crude acrylic acid is dissolved 13 kg/h Z to obtain inhibitor solution I. 30 kg/h of inhibitor solution I dissolve 19 kg/h MEHQ with the formation of the inhibitor solution II.

Separated in the wash column of the mother solution first served heated in the collector and then into the tank. There it is heated up to 90°C and the number 71759 kg/h through the pipe 13 back to the fifteenth twin plate 12 of the condensation column 28 (bottom). Returned to the mother liquor has the following composition:

94,4349 wt.% acrylic acid,

0,5504 wt.% acetic acid,

3,4362 wt.% water,

0,0172 wt.% formic acid,

0,0018% wt. formaldehyde,

0,0109 wt.% acrolein,

0,0756 wt.% propionic acid,

0,3580 wt.% furfural,

0,0034% wt. allylacetate,

0,0003% wt. alifornia,

0,0933 wt.% benzaldehyde,

0,2986 wt.% maleic anhydride,

0,6808 wt.% diacrylates KIS is the notes,

0,0150% wt. fenotiazina,

0,0233 wt.% Q and

of 0.0005 wt.% the oxygen.

Additionally, a two-line plate 12 return 15224 kg/h unloaded from the national team of the plates 14 of the crude acrylic acid (32).

Through 2.9 m above the second catching plate 14 in the condensation column 28 is the first (16) subsequent 21 equidistant from each other twin plates (hole diameter 14 mm, number of holes 32020, the relative aperture of 17.4%), while the distance between the plates is 380 mm Return from the field plates of Tormann in the area of the double-flow plates is carried out using integrated in the column on the distribution system. Alternative return can be accomplished by discharging the circulating fluid from the lower plate of Tormann condensation of the column using a pump and return it by two (or more) pipes located above the highest two-line plate.

800 mm above the last of the arresting plate condensation column conically expanding. 500 mm above the last of the arresting plate such expansion of the condensation column ends, while its diameter is 6,50 m

At this height, that is 1.50 m above the last of the arresting plate (17)are equidistant from each other (distance between plates = 500 mm) 28 conventional single-threaded plates of Tormann. Tarel and Thormann arranged in such a manner, that by placing slots in the cap plates in the grooves of the transverse current can achieve the opposite direction of the current of liquid.

The ratio of the apertures of the plates of Tormann is 14%. The ratio of the surface of the pipe for exhaust gases to the surface of the outlet slot is 0.8. The height of the pipe and the height of the discharge threshold is 40 mm, the lumen of the plates (the distance between the bottom edge of the slot and plates) is 10 mm, the height of the slot is 15 mm, the angle between the slot and the edge of the cap is 30 degrees. The edge length of the cap is a maximum of 800 mm At the end of the casing, the length of the cap is reduced to 200 mm in order to fit it to the rounded shape of the column. The distance between the two caps that are in the direction of the cross current is 66 mm, the area of the drain discharge pipe is 1.5% of the area of the cross-current plate. The distance between the two lower edges of the cap is 64 mm.

At the height of the highest plate of Tormann 20 distillation column again begins to narrow conically. At a distance of 700 mm above the highest plate of Tormann this narrowing ends, and the inner diameter of the column again becomes equal to 6.00 PM

At a distance of 1.70 m above the highest plate of Tormann is the third absorbing plate 22 (the national dish, plate, having 16 ravno Alannah pipes for exhaust gases; the height of the pipe approximately 1.50 m). The volume of liquid in the third catching plate is 8 m3(mass density = 964,38 kg/m3).

From the third capture plates through line 23 is discharged 533617 kg/h of acid water at a temperature of 68.6°C and a pressure of 1.24 bar.

Acidic water has the following composition:

11,3387 wt.% acrylic acid,

4,1574 wt.% acetic acid,

81,6277 wt.% water,

0,5256 wt.% formic acid,

2,3082 wt.% formaldehyde,

0,0154 wt.% acrolein,

0,0089% wt. propionic acid,

0,0024% wt. furfural,

0,0135 wt.% alifornia,

0.0001 wt.% Q and

0,0021% wt. the oxygen.

29015 kg/h unloaded acidic water (68,6°C) (21) together with the inhibitor solution II (31) return to the top plate of Thormann (20).

812 kg/h of inhibitor solution I (bottom) load on the 19-th plate Thormann (18) (at 25°C and 3 bar pressure through line 19).

7282 kg/h unloaded sour water burn.

298392 kg/h unloaded acidic water through line 25 at a temperature of 29°C serves on the sixth (24) valve plate (bottom) (pressure 3 bar). In the case of foaming, it is advisable to add the non (for example, alkoxysilane alcohols, such as Dekresa® SD 23, or a mixture of fatty acids, polyglycol, emulsifiers and paraffin mixtures of mineral oils, such as Naico® 71-D-5) on the third catching the th plate (for example, in the amount of 30 ml/h).

198928 kg/h unloaded acidic water through the pipe 27 at a temperature of 22.5°C (p=3 bar) return to the top (26) of the valve plate.

At a distance of 2300 mm above the third catching plate 22 in the condensation column 28 at the same distance from each other (distance between plates = 500 mm) are 11 double-flow valve trays. The height of the discharge threshold is 35 mm, the ratio of the holes is 18%, and the sum of squares of drain drain pipes two consecutive valve plates is 10% of the cross-current plate. As the valves used W12-valves company Stahl, DE, Viemheim.

The pressure at the column head 28 is 1.2 bar. From the head of the distillation column 28 through mist eliminator unload 164650 kg/h exhaust gas (33)having a temperature of 33.5°C and the following composition:

0,2288 wt.% acrylic acid,

0,0885 wt.% acetic acid,

2,6689 wt.% water,

0,0052% wt. formic acid,

0,1724 wt.% acrolein,

is 0.0002 wt.% propionic acid,

0,0003% wt. furfural,

0,0012% wt. illinformed,

2,1235 wt.% CO2,

0,6939 wt.% WITH,

0,6487 wt.% propane,

0,3169 wt.% propylene,

4,7392 wt.% O2and

88,3123 wt.% N2.

In the indirect heat exchanger exhaust gas is heated to 38°C, after which 91196 kg/h of this ha is with the help of the circulating gas compressor (for example, centrifugal compressor) as the diluent gas is subjected to oxidation in the gas phase and the subsequent separation and 73455 kg/h exhaust gas burn.

In General, effective in separating chamber load separate threads, which have such a content of acrylic acid:

170008 kg/h of a mixture of the product gas obtained by the oxidation in the gas phase propylene, in which the content of acrylic acid is 11.8 wt.%;

21883 kg/h through the pipe 9 when the content of acrylic acid 8,7215 wt.%;

15224 kg/h through the pipe 32 when the content of acrylic acid 96,8011 wt.%;

71759 kg/h through the pipe 13 when the content of acrylic acid 94,4349 wt.%;

455855 kg/h through the pipe 30 when the content of acrylic acid 96,7887 wt.%;

81,2 kg/h through the pipe 19 when the content of acrylic acid 98,3360 wt.%;

29015 kg/h through the pipe 21 when the content of acrylic acid 11,3387 wt.%;

and 49 kg/h through the pipe 31 when the content of acrylic acid 60,2057 wt.%.

Thus, effectively separating chamber in a whole load 764605 kg/h mass flow, the content of acrylic acid in which is 71,907 wt.%. Thus, X=28,09 wt.%.

Mass flow, which is discharged from the effective separating chamber at a very high content of acrylic acid is discharged from the second precast the plates of the crude acrylic acid, the content of the fraction of acrylic acid in which is 96,8011 wt.%. Thus, Y=3,20 wt.%, and X:Y=8,78.

The total effective separating chamber filled with liquid, is 167,5 m3. The temperature of this fluid, at least partially, is 120,2°C (for example, in a heat exchanger with direct circulation).

In the following table 1 shows the volume elements i (and the "plate i" here means the volume element i, which includes being on mass transfer plate i in the liquid phase and the liquid phase in the zone under mass-transfer plate i (except for the liquid phase, which is located between the plate)). Numbering mass transfer plates of the distillation column starts from the bottom up.

In addition, table 1 shows the values of temperature Ticalculated values of msiand values of mass flow.

Table 1 also contains individual values of

Thus, ttotal=to 34.06 h

With this value of ttotalas discharged from the effective separating chamber mass flow containing (meth)acrylic monomers, the content of acrylic acid in which is 89978 kg/h, use ithout the crude acrylic acid, the content of the fraction of acrylic acid in which is 96,8011 wt.%.

Example (described stationary state)

All carried out, as described in the comparative example, the volume of the chamber 5 of the cube is reduced so that the holding capacity of the liquid in the chamber 5 cube on 59974,2 kg lower than in the comparative example (thus, the holding capacity of the liquid in volume element i, which includes the line 6, 6' and 2, and the pump 7, the camera 5 cube and evaporating device with direct circulation 1, the comparative example is 79965,6 kg, and example - 19991,4 kg).

In addition, the number of high-boiling fractions discharged from the first team of plates 10 and loaded into the evaporation apparatus with a direct circulation 1 is 74083 kg/h instead of 63009 kg/h

These changes are necessary in order by changing the composition of the bottom liquid in the chamber 5 of the cube to reduce the boiling temperature in the evaporation apparatus with a direct circulation 1.

Table 2 is similar to table 1 of the example.

Thus, ttotaljust 8,79 PM

Simultaneously with this value of ttotaldivided in effective separation chamber mass flow containing (meth)acrylic monomers, the content of acre the OIC acid which is 90987 kg/h, use of the crude acrylic acid, the content of acrylic acid in which is 96,9333 wt.%.

The analysis showed that this improvement is primarily due to the fact that the liquid phase in the cube 5 in the example by reducing the time spent has only 19,27% wt. polyacrylic acid (product of joining Michael).

1. thermal method of separation by fractional condensation of a mixture of the product gas obtained heterogeneous catalyzed partial oxidation in the gas phase of propene and/or propane to acrylic acid, for separating at least one mass flow of enriched acrylic acid from a mixture of the product gas containing acrylic acid, which includes continuous stationary operation, at least one device for thermal separation, containing at least one effective separating chamber with a distillation column having a mass transfer plates as built-dividing elements, which loads the mixture of product gas containing acrylic acid as at least one of the mass stream containing acrylic acid, and from which discharged, at least one mass stream containing acrylic acid, provided that
mass flow, which in General is loaded into effective RA the separating chamber and is obtained by adding downloadable effective in separating chamber separate mass flow, contains X wt.% other than acrylic acid components,
mass flow, which is discharged from the effective separating chamber with the largest proportion of acrylic acid, contains Y wt.% other than acrylic acid components,
the ratio of X: Y is ≥5,
effective separation chamber, except the place of loading and place of discharge of the stream is limited to the solid phase and contains, in addition to mass transfer plates as built-separation elements in a distillation column, at least one coolant heat exchanger, and
the total volume of the chamber filled with the liquid phase, is ≥1 m3, and the temperature of the liquid phase, at least partially, is ≥80°C,
when splitting an effective separating chamber into n individual volume elements, and the highest and lowest temperatures within a certain volume element of the liquid phase differ by no more than 2°C, and the volume element in effective separation chamber is continuous, the total residence time ttotal

≤20 h,
and
A=(Ti-Tabout)/10°C
Tabout=100°C
Ti= average of the highest and lowest temperature of the volume element i in the liquid phase, °C;
msi= total mass of acrylic acid is you, contained in the volume of the liquid phase volume element i;
= total number of paged from the volume element i of the flow of liquid-phase mass
and
,
assuming that the volume elements of i contained in the liquid-phase mass miandas a three-dimensional elements with a dead zone is also not included in the sum of all volume elements i like and three-dimensional elements of i that do not contain the liquid phase, and the total amount of the liquid phase contained in the three-dimensional elements with a dead zone is not more than 5 wt.% from the total amount of the liquid phase contained in the effective separation chamber.

2. The method according to claim 1, characterized in that X:Y≥8.

3. The method according to claim 1 or 2, characterized in that the total effective separation chamber filled with the liquid phase, is ≥5 m3.

4. The method according to claim 1 or 2, characterized in that the temperature of the liquid phase in the effective separation chamber, at least partially, is ≥100°C.

5. The method according to claim 1 or 2, characterized in that the ttotal≤15 p.m.

6. The method according to claim 1 or 2, characterized in that the ttotal≤10.

7. The method according to claim 1 or 2, characterized in that the circulation heat exchanger is a coolant circulation evaporating device.

8. The method according to claim 1 or 2, characterized in that circul the operating heat exchanger is an evaporator unit with direct circulation.

9. The method according to claim 1 or 2, characterized in that the ttotal≤10 h, the content of the fraction of acrylic acid in a mixture of the product gas partial oxidation in the gas phase is from 5 to 15 wt.%, and unloaded from the effective separating chamber mass flow containing the largest weight fraction of acrylic acid, is a crude acrylic acid content fraction of acrylic acid which is ≥95 wt.%.

10. The method according to claim 1, characterized in that under mass transfer plates from the bottom up first, we are talking about double-flow plates, then a hydraulically sealed plates with transverse current, and then the valve plates.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: proposed method involves the following stages: (a) reaction of carbon monoxide with at least one reagent chosen from a group, consisting of methanol, methyl acetate, methyl formate and dimethyl ether and their mixture in a reaction medium, containing water, methyl iodide and catalyst for obtaining the reaction product, containing acetic acid; (b) gas-liquid separation of the said reaction product to obtain a volatile phase, containing acetic acid, water and methyl iodide and a less volatile phase, containing the said catalyst; (c) distillation of the above mentioned volatile phase to obtain a purified product of acetic acid and a first overhead fraction, containing water, methylacetate and methyl iodide; (d) phase separation of the above mentioned first overhead fraction to obtain the first liquid phase, containing water, and second liquid phase, containing methyl iodide and methyl acetate; and (e) feeding dimethyl ether directly or indirectly into a decantation tank of light fractions for phase separation of the said first overhead fraction in a quantity, sufficient for increasing separation of the first overhead fraction to form the first and second liquid phases.

EFFECT: improvement of the method of producing acetic acid.

8 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: method of (meth)acrylic acid purification includes the stages as follows: distillations of the liquid containing raw (meth)acrylic acid being acrylic acid or methacrylic acid with one or more polymerisation inhibitors added as chosen from group consisting of phenol derivative, phenothiazine derivative, copper (meth)acrylate and copper dithiourethane, for the purpose to produce condensate of (meth)acrylic acid, containing (meth)acrylic acid of purity at least 90%; adding polymerisation inhibitor containing phenol derivative to condensate; and delivery of oxygen-containing gas that contains oxygen to condensate of (meth)acrylic acid in reflux tank wherein condensate of (meth)acrylic acid is collected, wherein oxygen-containing gas is delivered to condensate in reflux tank with using small-size bubble liquid injector, and pressure connection for oxygen-containing gas delivery to liquid injector whereat ratio (nm/tn) of oxygen delivery in oxygen-containing gas and condensate flow supplied to reflux tank at 0°C, 1 atm complies with ratio shown in equation 0.004≤A/B≤1.0, where A stands for O2 delivery (nm3/hour), B stands for condensate flow (tn/hour) of the condensate supplied to reflux tank, and symbol n in nm3/hour specifies the value under normal conditions (0°C, 1 atm: normal conditions).

EFFECT: effective method of high purity acid production wherein acid polymer formation in made condensate is prevented.

12 cl, 6 dwg, 7 ex

FIELD: chemistry.

SUBSTANCE: present invention pertains to improvement of the method of producing (met)acrylic acid and complex (met)acrylic esters, involving the following stages: (A) reacting propane, propylene or isobutylene and/or (met)acrolein with molecular oxygen or with a gas, containing molecular oxygen through gas-phase catalytic oxidation, obtaining crude (met)acrylic acid; (B) purification of the obtained crude (met)acrylic acid, obtaining a (met)acrylic acid product; and (C) reacting raw (met)acrylic acid with alcohol, obtaining complex (met)acrylic esters, in the event that the installation used in any of the stages (B) and (C), taking place concurrently, stops. The obtained excess crude (met)acrylic acid is temporarily stored in a tank. After restoring operation of the stopped installation, the crude (met)acrylic acid, stored in the tank, is fed into the installation, used in stage (B), and/or into the installation used in stage (C). (Met)acrylic acid output of the installation used in stage (A) should be less than total consumption of (met)acrylic acid by installations used in stages (B) and (C).

EFFECT: the method allows for processing (met)acrylic acid, temporarily stored in a tank, when stage (B) or (C) stops, without considerable change in workload in stage (A).

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FIELD: chemistry.

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EFFECT: efficient and fast cleaning of distillation column with extraction of valuable substance.

5 cl, 5 dwg, 3 ex

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to separation of product and by-product stream in production of alkylaromatic acids, in particular terephthalic acid, via oxidation of hydrocarbon with molecular oxygen in acetic acid solution. In order to recover acetic acid, it is separated from methyl acetate in distillation column in the form of bottom stream. Distillate containing methyl acetate by-product is catalytically hydrolyzed in hydrolysis reactor using preferably water withdrawn from emission gas washing column. Non-decomposed methyl acetate is separated from methanol and recovered in the form of high-concentration aqueous solution by extractive distillation with water, after which routed back to hydrolysis so that essentially all methyl acetate by-product is recovered and reused in the form of acetic acid. Reaction mixture in the hydrolysis stage contains no more than 30% acetic acid and weight amount of water by 3 or more times exceeding amount of recovered methyl acetate.

EFFECT: improved economic characteristics of process due to reduced loss of acetic acid and additional recovery of acetic acid when performing hydrolysis of methyl acetate.

6 cl, 3 dwg, 6 tbl, 3 ex

The invention relates to an improved method of isolation and purification of adipic acid, used for the production of polyamide-6,6 or polyurethanes, which consists in treating the reaction mixture obtained by direct oxidation of cyclohexane to adipic acid by molecular oxygen in an organic solvent and in the presence of a catalyst, removing by-products from the reaction mixture and the adipic acid by crystallization, and before adipic acid from the reaction environment carry out consistently the following operations: the decantation of the two phases of the reaction medium with the formation of the upper organic the cyclohexane phase, containing mainly cyclohexane, and the lower phase, containing mainly the solvent, the resulting dicarboxylic acid, the catalyst and other reaction products and unreacted cyclohexane; distillation bottom phase to separate, on the one hand, distillate containing at least a part of the most volatile compounds, such as organic solvent, water and unreacted cyclohexane, cyclohexanone, cyclohexanol, complex cyclohexylamine esters and possibly lactones, and, with the pin acid from residue from distillation by means of crystallization and thus obtained crude adipic acid is subjected in aqueous solution purification by hydrogenation and/or oxidation with subsequent crystallization and recrystallization of the purified adipic acid in water

The invention relates to an improved method of processing the reaction mixture formed by the reaction of direct oxidation of hydrocarbons to carboxylic acids

The invention relates to the production of acetic acid

The invention relates to a method of reducing and/or removing permanganatometricly compounds, such as acetaldehyde, propionic acid and alkylidene impurities in the process of carbonylation of methanol

FIELD: chemistry.

SUBSTANCE: proposal is given of a method of removing impurities from a water mixture or purified water mixture through extraction of the water mixture or purified water mixture using an extractive solvent in the extraction zone with formation of a stream of extract and a stream of raffinate and, optionally, separation of the extract stream and the solvent rich stream in the separation zone with formation of a stream of organic impurities with high boiling point and a stream of extractive solvent.

EFFECT: provision for extracting metallic catalyst in active form, reusable at the paraxylene recycling stage.

29 cl, 2 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: method of obtaining product - purified carboxylic acid, includes: (a) oxidation of aromatic initial materials in primary oxidation zone with formation of raw carboxylic acid suspension; where raw carboxylic acid suspension contains terephthalic acid; where said oxidation is carried out at temperature within the range from 120°C to 200°C; (b) withdrawal of admixtures from raw suspension of carboxylic acid, removed at temperature from 140°C to 170°C from stage of oxidation of paraxylol in primary oxidation zone and containing terephthalic acid, catalyst, acetic acid and admixtures, realised in zone of solid products and liquid separation with formation of mother liquid flow and product in form of suspension; where part of said catalyst in said suspension of raw carboxylic acid is removed in said mother liquid flow; and where into said zone of solid products and liquid separation optionally additional solvent is added; (c) oxidation of said product in form of suspension in zone of further oxidation with formation of product of further oxidation; where said oxidation is carried out at temperature within the range from 190°C to 280°C; and where said oxidation takes place in said zone of further oxidation at temperature higher than in said primary oxidation zone; (d) crystallisation of said product of further oxidation in crystallisation zone with formation of crystallised product in form of suspension; (e) cooling of said crystallised product in form of suspension in cooling zone with formation of cooled suspension of purified carboxylic acid; and (i) filtration and optionally drying of said cooled suspension of purified carboxylic acid in filtration and drying zone in order to remove part of solvent from said cooled suspension of carboxylic acid with obtaining of said product - purified carboxylic acid.

EFFECT: purified carboxylic acid with nice colour and low level of admixtures, without using stages of purification like hydration.

8 cl, 1 tbl, 1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: method of separating multi-atom alcohols, for instance, neopentylglycol and sodium formiate, includes evaporation and cooling of reaction mixture, addition of organic solvent, crystallisation of sodium formiate, separation of sodium formiate from saturated solution of multi-atom alcohol, for instance, by filtration, and crystallisation of multi-atom alcohol. Reaction mixture is evaporated until two liquid layers are formed, which are separated into light phase - water-multi-atom alcohol and heavy phase -water-salt, separated water-salt fraction of solution is cooled until sodium formiate contained in it in form of cryslallohydrate is crystallised, sodium formiate crystals are separated, and remaining mother-solution is returned to process head, to evaporation stage, then separated light phase - water-multi-atom alcohol is additionally evaporated until 70% of contained in it sodium formiate is crystallised, then cooled to 25-30°C and subjected to processing with organic solvent from line of single-atom saturated alcohols, for instance, methane, for removal of remaining admixtures, with further crystallisation of multi-atom alcohol from remaining mother-solution.

EFFECT: reduction of amount of used organic solvent, elimination of high-temperature stage of extraction, preservation of yield of pure target products.

2 cl, 2 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method, by which the carboxylic acid/diol mixture, that is suitable as the initial substance for the manufacture of polyester, obtained from the decolourised solution of carboxylic acid without actually isolating the solid dry carboxylic acid. More specifically, the invention relates to the method of manufacturing a mixture of carboxylic acid/diol, where the said method includes the addition of diol to the decolourised solution of carboxylic acid, which includes carboxylic acid and water, in the zone of the reactor etherification, where diol is located at a temperature sufficient for evaporating part of the water in order to become the basic suspending liquid with the formation of the specified carboxylic acid/diol mixture; where the said carboxylic acid and diol enter into a reaction in the zone of etherification with the formation of a flow of a complex hydroxyalkyl ether. The invention also relates to the following variants of the method: the method of manufacture of the carboxylic acid/diol mixture, where the said method includes the following stages: (a) mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of damp carboxylic acid; where the said carboxylic acid is selected from the group, which includes terephthalic acid, isophthatic acid, naphthalenedicarboxylic acid and their mixtures; (b) discolourisation of aforesaid solution of damp carboxylic acid in the zone for reaction obtaining the decolourised solution of carboxylic acid; (c) not necessarily, instantaneous evaporation of the said decolourised solution of carboxylic acid in the zone of instantaneous evaporation for the removal of part of the water from the decolourised solution of carboxylic acid; and (d) addition of diol to the decolourised solution of carboxylic acid in the zone of the reactor of the etherification, where the said diol is located at a temperature, sufficient for the evaporation of part of the water in order to become the basic suspending liquid with the formation of the carboxylic acid/diol mixture; where the aforesaid carboxylic acid and diol then enter the zone of etherification with the formation of the flow of complex hydroxyalkyl ether; and relates to the method of manufacture of carboxylic acid/diol, where the said method includes the following stages: (a) the mixing of the powder of damp carboxylic acid with water in the zone for mixing with the formation of the solution of carboxylic acid; (b) discolourisation of the said solution of damp carboxylic acid in the reactor core with the formation of the decolourised solution of carboxylic acid; (c) crystallisation of the said decolourised solution of carboxylic acid in the zone of crystallisation with the formation of an aqueous suspension; and (d) removal of part of the contaminated water in the aforesaid aqueous solution and addition of diol into the zone of the removal of liquid with the obtaining of the said carboxylic acid/diol mixture, where diol is located at a temperature sufficient for evaporating part of the contaminated water from the said aqueous suspension in order to become the basic suspending liquid.

EFFECT: obtaining mixture of carboxylic acid/diol.

29 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: invention pertains to the perfection of the method of regulating quantities of dissolved iron in liquid streams during the process of obtaining aromatic carboxylic acids or in the process of cleaning technical aromatic carboxylic acids, characterised by that, to at least, part of the liquid stream for regulating the quantity of dissolved iron in it, at least one peroxide with formula R1-O-O-R2 is added. Here R1 and R2 can be the same or different. They represent hydrogen or a hydrocarbon group, in quantities sufficient for precipitation of the dissolved iron from the liquid. The invention also relates to the perfection of the method of obtaining an aromatic carboxylic acid, through the following stages: A) contacting the crude aromatic material which can be oxidised, with molecular oxygen in the presence of an oxidising catalyst, containing at least, one metal with atomic number from 21 to 82, and a solvent in the form of C2-C5 aliphatic carboxylic acid in a liquid phase reaction mixture in a reactor under conditions of oxidation with formation of a solid product. The product contains technical aromatic carboxylic acid, liquid, containing a solvent and water, and an off-gas, containing water vapour and vapour of the solvent; B) separation of the solid product, containing technical aromatic carboxylic acid from the liquid; C) distillation of at least part of the off gas in a distillation column, equipped with reflux, for separating vapour of the solvent from water vapour. A liquid then forms, containing the solvent, and in the upper distillation cut, containing water vapour; D) returning of at least, part of the liquid from stage B into the reactor; E) dissolution of at least, part of the separated solid product, containing technical aromatic carboxylic acid, in a solvent from the cleaning stage with obtaining of a liquid solution of the cleaning stage; F) contacting the solution from the cleaning stage with hydrogen in the presence of a hydrogenation catalyst and under hydrogenation conditions, sufficient for formation of a solution, containing cleaned aromatic carboxylic acid, and liquid, containing a cleaning solvent; G) separation of the cleaned aromatic carboxylic acid from the solution, containing the cleaning solvent, which is obtained from stage E, with obtaining of solid cleaned aromatic carboxylic acid and a stock solution from the cleaning stage; H) retuning of at least, part of the stock solution from the cleaning stage, to at least, one of the stages B and E; I) addition of at least, one peroxide with formula R1-O-O-R2, where R1 and R2 can be the same or different, and represent hydrogen or a hydrocarbon group, in a liquid from at least one of the other stages, or obtained as a result from at least one of these stages, to which the peroxide is added, in a quantity sufficient for precipitation of iron from the liquid.

EFFECT: controlled reduction of the formation of suspension of iron oxide during production of technical aromatic acid.

19 cl, 1 dwg, 6 ex, 4 tbl

FIELD: chemical industry; methods of production of the purified crystalline terephthalic acid.

SUBSTANCE: the invention is pertaining to the improved method of production and separation of the crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid. The method provides for the following stages: (1) loading of (i) para- xylene, (ii) the water reactionary acetic-acidic medium containing the resolved in it components of the oxidation catalyst, and (iii) the gas containing oxygen fed under pressure in the first zone of oxidation, in which the liquid-phase exothermal oxidization of the para-xylene takes place, in which the temperature and the pressure inside the first being under pressure reactor of the oxidization are maintained at from 150°С up to 180°С and from 3.5 up to 13 absolute bars; (2) removal from the reactor upper part of the steam containing the evaporated reactionary acetic-acidic medium and the gas depleted by the oxygen including carbon dioxide, the inertial components and less than 9 volumetric percents of oxygen in terms of the non-condensable components of the steam; (3) removal from the lower part of the first reactor of the oxidized product including (i) the solid and dissolved terephthalic acid and (ii) the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (4) loading of (i) the oxidized product from the stage (3) and (ii) the gas containing oxygen, into the second being under pressure zone of the oxidation in which the liquid-phase exothermal oxidization of the products of the non-complete oxidization takes place; at that the temperature and the pressure in the second being under pressure reactor of the oxidization are maintained from 185°С up to 230°С and from 4.5 up to 18.3 absolute bar; (5) removal from the upper part of the second steam reactor containing the evaporated water reactionary acetic-acidic medium and gas depleted by the oxygen, including carbon dioxide, the inertial components and less, than 5 volumetric percents of oxygen in terms of the non-condensable components of the steam; (6) removal from the lower part of the second reactor of the second oxidized product including (i) the solid and dissolved terephthalic acid and the products of the non-complete oxidation and (ii) the water reactionary acetic-acidic medium containing the dissolved oxidation catalyst; (7) separation of the terephthalic acid from (ii) the water reactionary acetic-acidic medium of the stage (6) for production the terephthalic acid containing less than 900 mass ppm of 4- carboxybenzaldehyde and the p-toluene acid; (8) dissolution of the terephthalic acid gained at the stage (7) in the water for formation of the solution containing from 10 up to 35 mass % of the dissolved terephthalic acid containing less than 900 mass ppm of the 4- carboxybenzaldehyde and the p-toluene acid in respect to the mass of the present terephthalic acid at the temperature from 260°С up to 320°С and the pressure sufficient for maintaining the solution in the liquid phase and introduction of the solution in contact with hydrogen at presence of the catalytic agent of hydrogenation with production of the solution of the hydrogenated product; (9) loading of the solution of the stage (8) into the crystallization zone including the set of the connected in series crystallizers, in which the solution is subjected to the evaporating cooling with the controlled velocity using the significant drop of the temperature and the pressure for initiation of the crystallization process of the terephthalic acid, at the pressure of the solution in the end of the zone of the crystallization is atmospheric or below; (10) conduct condensation of the dissolvent evaporated from the crystallizers and guide the condensed dissolvent back into the zone of the crystallization by feeding the part of the condensed dissolvent in the line of removal of the product of the crystallizer, from which the dissolvent is removed in the form of the vapor; and (11) conduct separation of the solid crystalline terephthalic acid containing less than 150 mass ppm of the p-toluene acid in terms of the mass of the terephthalic acid by separation of the solid material from the liquid under the atmospheric pressure. The method allows to obtain the target product in the improved crystalline form.

EFFECT: the invention ensures production of the target product in the improved crystalline form.

8 cl, 3 tbl, 2 dwg, 3 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for isolating crystalline terephthalic acid comprising less 150 mas. p. p. per million (ppm) of p-toluic acid with respect to weight of terephthalic acid. Method involves the following steps: (1) preparing a solution containing from 10 to 35 wt.-% of dissolved terephthalic acid wherein from 150 to 1100 ppm of p-toluic acid is dissolved with respect to mass of terephthalic acid at temperature from 260°C to 320°C and under pressure providing maintaining the solution in liquid phase; (2) charge of solution from step (1) to crystallization zone comprising multitude amount of associated crystallizers wherein the solution is subjected for cooling at evaporation at the controlled rate by the moderate pressure and temperature reducing resulting to crystallization of terephthalic acid and wherein the solution pressure at the end of crystallization zone is equal to atmosphere pressure or lower; (3) condensation of solvent evaporated from crystallizers and recovering the condensed solution to the crystallization zone to place of descending flow from crystallizer wherein solvent is removed by evaporation, and (4) isolation of solid crystalline terephthalic acid comprising less 150 ppm of p-toluic acid with respect to the terephthalic acid mass by separation of the phase liquid-solid substance under atmosphere pressure. The advantage of method is preparing the end product in improved crystalline form and carrying out the process under atmosphere pressure or pressure near to atmosphere pressure.

EFFECT: improved method of crystallization.

3 cl, 1 dwg, 1 tbl, 2 ex

FIELD: crystal growing.

SUBSTANCE: invention relates to adipic acid crystals and treatment thereof to achieve minimum crystal caking. Crystals are prepared by crystallization of adipic acid from aqueous medium or between treating it with aqueous solution. Crystals are then subjected to ripening stage, that is crystals are held at temperature between 10 and 80°C until content of exchangeable water in crystals falls below 100 ppm, while using an appropriate means to maintain ambient absolute humidity at a level of 20 g/m3. Renewal of ambient medium is accomplished by flushing crystal mass with dry air flow having required absolute humidity. Means to maintain or to lower absolute humidity contains moisture-absorption device placed in a chamber. Content of exchangeable water in crystals is measured for 300 g of adipic acid crystals, which are enclosed in tightly sealed container preliminarily flushed with dry air and containing 2 g of moisture absorbing substance. In chamber, temperature between 5 and 25°C is maintained for 24 h. Content of water will be the same as amount of water absorbed by absorbing substance per 1 g crystals. Total content of water exceeds content of exchangeable water by at least 20 ppm.

EFFECT: minimized caking of crystals and improved flowability.

13 cl, 5 ex

The invention relates to an improved method of reducing the content of 4-carboxybenzene in the production of terephthalic or 3-carboxymethylthio in the production of isophthalic acid, comprising: (a) dissolving crude terephthalic acid or crude isophthalic acid in a solvent at a temperature of from 50 to 250With obtaining a solution; (b) crystallization of the purified acid from this solution by reducing the temperature and/or pressure; (C) the Department specified crystallized terephthalic acid or isophthalic acid from the solution; (d) adding an oxidant to the reactor oxidation carboxyanhydride for oxidation specified filtered solution of stage (C), leading to the transformation of 4-carboxybenzene or 3-carboxymethylthio in terephthalic acid or isophthalic acid; (e) evaporating the solvent from this solution from step (d); (f) cooling the concentrated solution from step (e) for crystallization additional quantities of purified terephthalic acid or isophthalic acid and filtering the specified slurry and recycling the most part, the mother liquor from step (f) in the devices is

The invention relates to an improved method of processing the reaction mixture obtained by direct oxidation of cyclohexane to adipic acid, in liquid phase, in a solvent and in the presence of dissolved in the reaction medium, catalyst, including decantation two liquid phases: upper non-polar phase containing mainly unreacted cyclohexane, and the lower polar phase containing mainly solvent, adipic acid and the resulting acid, the catalyst and other reaction products and unreacted hydrocarbons, distillation of the lower polar phase or, if necessary, the entire reaction mixture with obtaining, on the one hand, distillate, containing, at least a part of the most volatile compounds such as unreacted cyclohexane, the solvent, the intermediate reaction products and water, and, on the other hand, residue from distillation, containing adipic acid and the resulting carboxylic acid, the catalyst, and the method includes a step of adding to the residue after distillation of the organic solvent in which adipic acid has a solubility less than or equal to 15 wt

FIELD: chemistry.

SUBSTANCE: proposed method involves the following stages: (a) reaction of carbon monoxide with at least one reagent chosen from a group, consisting of methanol, methyl acetate, methyl formate and dimethyl ether and their mixture in a reaction medium, containing water, methyl iodide and catalyst for obtaining the reaction product, containing acetic acid; (b) gas-liquid separation of the said reaction product to obtain a volatile phase, containing acetic acid, water and methyl iodide and a less volatile phase, containing the said catalyst; (c) distillation of the above mentioned volatile phase to obtain a purified product of acetic acid and a first overhead fraction, containing water, methylacetate and methyl iodide; (d) phase separation of the above mentioned first overhead fraction to obtain the first liquid phase, containing water, and second liquid phase, containing methyl iodide and methyl acetate; and (e) feeding dimethyl ether directly or indirectly into a decantation tank of light fractions for phase separation of the said first overhead fraction in a quantity, sufficient for increasing separation of the first overhead fraction to form the first and second liquid phases.

EFFECT: improvement of the method of producing acetic acid.

8 cl, 1 dwg

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