Vapor-phase catalytic oxidation process

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to a process of catalytic oxidation in vapor phase, which prevents emergence of non-controllable reaction and premature poisoning of catalyst in (meth)acrylic acid synthesis. Vapor-phase catalytic oxidation process, wherein feed gas is supplied for oxidation to reaction tubes of multi-tubular reactor provided with multiple, disposed in reactor shell, reaction tubes filled with catalyst and multiple deflectors serving to modify direction of heat-carrier stream introduced into reactor shell. Temperature is measured in catalyst, which is placed in a reaction tube and is not connected with at least one deflector, as well as temperature in catalyst, which is placed in a reaction tube and is connected with all deflectors.

EFFECT: ensured continuous production of (meth)acrylic acid with high yield and for a long period of time.

12 cl, 6 dwg, 4 ex

The technical field to which the invention relates

The present invention relates to a method of catalytic oxidation in the vapor phase, which prevents the uncontrolled reaction or premature poisoning of the catalyst in the production of (meth)acrylic acid or similar substances from propylene or isobutylene by catalytic oxidation in the vapor phase using mnogotranshevogo reactor and which provides a constant high production for the maximum possible period of time.

Description of the prior art

Normal Novotrubny reactor has a design supplied located inside containment many reaction tubes, which are incorporated in the catalyst, and many baffles having openings for the distribution of the coolant supplied into the shell, around the area, limited by the shell. The usual practice was provided for measuring the temperature of the coolant flowing inside the shell, and on the basis of the results of measurements carried out the operation mnogotranshevogo reactor at a uniform temperature control of the coolant in the shell.

Most of the reaction tubes arranged in a casing, connected to the deflectors. However, part of the reaction tubes passing through about what verste, formed in the baffles, are not connected to the deflectors. The catalyst layers in the reaction tubes that are not in contact with the deflectors, subject to local accumulation of heat (education sites overheating caused by heat of reaction. If you are sites of local overheating, part of the catalyst susceptible to poisoning due to excess heat generation, and its service life is reduced.

In addition, to obtain the proper characteristics for the life of the catalyst by preventing the formation of local overheating was required to reduce the concentration of raw material gas fed into the reaction tube, or limiting the amount of gas, resulting in a situation arises where it is impossible to produce (meth)acrylic acid or a similar substance with a high output for a long period of time.

Description of the invention

The present invention relates to a method of catalytic oxidation in the vapor phase using mnogotranshevogo reactor, through which can be solved the above problems, and the method includes the following items.

(1) a Method of catalytic oxidation in the vapor phase, in which the raw gas is fed to the oxidation reaction tubes mnogotranshevogo reacto is a, with many located inside the containment of the reaction tubes, which are incorporated in the catalyst, and plenty of vents for changing the direction of flow of the coolant supplied into the shell, characterized in that the measured temperature of the catalyst incorporated in the reaction tube is not connected with at least one deflector.

(2) a Method of catalytic oxidation in the vapor phase, in which the raw gas is fed to the oxidation reaction tubes mnogotranshevogo reactor, which is equipped with located inside containment many reaction tubes containing enshrined in the catalyst, and plenty of vents for changing the direction of flow of the coolant supplied into the shell, characterized in that the measured temperature of the catalyst incorporated in the reaction tube is not connected with at least one baffle, and the temperature of the catalyst, which is incorporated in the reaction tube, which is connected with all the vents.

(3) the Method according to p.p. (1) or (2)in which on the basis of the measured temperature of the catalyst regulate the temperature and flow rate of the coolant supplied into the shell.

(4) the Method according to any of the points (1)to(3), in which the temperature of the catalyst is measured in 2-20 points in the direction of the axis of the reaction tube.

(5) the Method according to any of the points (1)to(4), in the cat the rum temperature of the catalyst is measured using a multipoint thermocouple.

(6) the Method according to any of the points (1)to(5), in which the flow of raw gas, which takes place in the reaction tube, and the macroscopic flow of the heat carrier, which is held in the shell, move in the same direction.

(7) the Method according to any of the points (1)to(6), where in the reaction pipe laying multiple layers of catalyst, which have different activity.

(8) the Method according to any of the points (1)to(7), in which the raw material gas as the oxidizable substance contains propylene, isobutylene or (meth)acrolein.

Brief description of drawings

Fig. 1 is a sectional view of the exemplary embodiment mnogotranshevogo reactor used for implementing the method of catalytic oxidation in the vapor phase.

Fig. 2 is a perspective view of the exemplary embodiment of the vent, which is provided with Novotrubny reactor.

Fig. 3 is a perspective view of another exemplary embodiment of the vent, which is provided with Novotrubny reactor.

Fig. 4 is a top view of mnogotranshevogo reactor shown in Fig. 1.

Fig. 5 is a sectional view of another exemplary embodiment mnogotranshevogo reactor used for implementing the method of catalytic oxidation in the vapor phase.

Fig. 6 is a partial view of a cross section of the plate, located in the middle part of the pipe, and the heat-shielding plate, which is provided with Novotrubny the reactor shown in Fig. 5.

Description silo the different rooms

1A, 1b, 1C: the reaction pipe;

2: shell mnogotranshevogo reactor;

5A, 5b: plate for fastening pipes;

6A, 6b: baffle;

9: plate for fastening the middle part of the pipe;

11: thermometer for measuring the temperature of the catalyst;

14, 15: thermometer for measuring the temperature of the coolant;

Hm: coolant;

Rg: raw gas.

Option of carrying out the invention

Method of catalytic oxidation in the vapor phase, corresponding to the present invention will be described based on the accompanying drawings.

Method of catalytic oxidation in the vapor phase, corresponding to the present invention, and Novotrubny the reactor used for carrying out the method of catalytic oxidation in the vapor phase will be described based on Fig. 1.

Number 2 marked shell mnogotranshevogo reactor, in which by means of the lower plate 5b for fastening pipes and the top plate 5A for mounting pipes installed the reaction tubes 1A, 1b and 1C, which are incorporated in the catalyst.

On the upper and lower ends of the shell 2 are the inlet and outlet openings 4A and 4b for the raw material gas Rg for the implementation of the reaction, and the raw material gas Rg passes through the reaction tubes 1A, 1b and 1C up or down. The flow direction is not limited to a particular option, but the upward direction is more preferable.

To the ome, on the outer periphery of the shell 2 has an annular pipe 3A coolant Hm, and the circular pipe 3A in the shell 2 serves Hm carrier under pressure, elevated circulating pump 7. The fluid pumped into the shell 2, is held up when the direction of flow is changed by the deflectors 6A, 6b and 6A, as shown by the arrows. When the coolant Hm absorbs the heat of reaction when they come into contact with the external surfaces of the reaction tubes 1a, 1b and 1C, and then returns to the circulating pump 7 through the ring pipe 3b mounted on the outer periphery of the shell 2.

Part of the heat medium Hm, which absorbed the heat of reaction, enters the exhaust pipe 8b, located in the upper part of the circulating pump 7 to the cooling heat exchanger (not shown), after which it is sucked by the circulating pump 7 through a pipe 8A coolant for submission to the shell 2.

Regulation of the temperature of the heating medium Hm, served in the shell 2, is implemented by regulating the temperature and flow rate of the coolant flowing through the pipe 8A coolant. In addition, the temperature of the heat medium Hm is measured by thermometer 14, located at the entrance of the ring pipe 3A.

On each copper plate inside the annular piping and b is rectifying plate (not shown) for mi is imitatie annular flow distribution of the coolant. As a rectifying plate is used, for example, a porous plate or a plate having slits. By changing the square holes of the porous plate or the distance between the slits is possible to regulate the flow of coolant Hm so that the carrier arrived in the shell 2 along its entire periphery with a constant flow and with a constant volume flow. In addition, as shown in figure 4, the circumference of the shell with equal intervals are many thermometers 15, through which you can monitor the temperature in the annular pipe (3A and, more preferably, also in the pipe 3b).

Usually in the shell 2 are at least three baffle (6A, 6b, and 6A). Due to the presence of baffles, the flow of coolant Hm in the shell 2 is arranged in such a way that it first converges from the peripheral part to the Central part of the shell 2 and is then routed to the external periphery, rising up through the open portion of the deflector 6A and reaching the inner wall of the shell 2.

Then the direction of flow of the heat medium Hm changed again, and the fluid passes up through the space between the inner wall of the shell 2 and the outer peripheral edge of the baffle 6b and converges to the Central part. He then rises up through the open portion of the deflector 6A, runs along the bottom surface in which RNA plate 5A for fastening pipes and reaches the outer peripheral part, then he enters the ring pipe 3b and finally absorbed by the circulating pump 7 for directions again in the shell 2.

As specific structures of deflectors used according to the present invention, it is possible to use the vent segment type in the form of an incomplete circle, as shown in Fig. 2, or round air vents, as shown in Fig. 3. When using deflectors, these types of relationship between the direction of flow of the heat carrier and the axis of the reaction tube does not matter.

Deflectors 6A have an external diameter matching the diameter of the inner wall of the shell 2 and are open in the city centre. The outside diameter of the baffle 6b smaller than the diameter of the inner wall of the shell 2, resulting in a between the outer peripheral edge of the baffle 6b and the inner wall of the shell 2 is formed a free space. The coolant flow is changed by changing the direction of flow when the coolant passes through the corresponding opening part and the free space.

In each reaction tube 1A, 1b and 1C, located in the shell 2, placed thermometer 11, the signals from which are transmitted outward from the shell 2, thanks to provide measurements of the temperature distribution in the catalyst incorporated in the reaction tube in the axial direction the drop pipe.

To the reaction tubes 1A, 1b and 1C are placed thermometers multidrop or thermometers 11, roaming in the shell, to perform measurements at several sites, making lead temperature measurement in 2-20 points in the axial direction.

The inner space of the casing 2, provided the reaction tubes 1A, 1b and 1C, separated by three deflectors 6A, 6b and 6C,and separated space is classified into three types in respect to the flow direction of the heat medium Hm.

Namely, the reaction tube 1A is connected to the baffle 6b, whereby the direction of flow of the heat medium Hm is limited only by the baffle 6b, and the flow direction is not limited by other deflectors 6A as it passes through the open parts of these deflectors 6A.

The heat medium Hm is supplied through the annular pipe 3A in the shell 2, changes the direction of the flow in the Central part of the shell 2, as shown by the arrows in Fig. 1. The reaction tube 1A is positioned in such a way that in the area where the flow direction is changed, resulting in Hm carrier passing around the outer periphery of the reaction tubes 1A, for the most part runs parallel to the axis of the reaction tube 1A.

The reaction tube 1b is connected with three baffles 6A, 6b and 6A, when the direction of flow of the heat medium Hm is limited to the relevant Def what cerami. In addition, the flow of coolant Hm, passing around the outer peripheral surface of the reaction tube 1b, is perpendicular to the axis of the reaction tube 1b approximately over the entire length of the reaction tube 1b. Most of the reaction tubes in the shell 2 are like the location of the reaction tube 1b.

The reaction tube 1 passes through the space between the outer periphery of the baffle 6b and the inner wall of shell 2 without entering into contact with the baffle 6b, the flow of coolant Hm in this area is not limited by the baffle 6b and runs parallel to the axis of the reaction tube 1C.

Figure 4 shows the relationship between the location of the reaction tubes 1a, 1b and 1C and deflectors 6A, 6b and 6A and flows coolant Hm.

When the open part of the deflectors BA (the inner circle shown by the dotted line) is the area of convergence of the heat medium Hm in the center of the shell 2, the heat medium Hm is not simply runs parallel to the reaction tube 1A, but almost never takes place in the center of the open part of the deflectors 6A, that is, the flow is almost zero, due to which the efficiency of heat transfer is extremely small. For this reason, the reaction tube 1A do not have in this position.

In Fig. 5 shows another exemplary embodiment of the present invention, in which the inner shell 2 d is ktora separated by a plate 9, located in the middle part of the pipe.

In separated from other spaces in the shell 2 circulating fluids Hm₁and Hm₂respectively, and regulate the temperature accordingly.

The top and bottom of the reaction tubes 1A, 1b and 1C are separated by an intermediate layer of inert material that does not react, they accordingly laid different catalysts and temperatures of the respective catalysts adjust for optimal conditions for reactions. In addition, the location of such intermediate inert material complies with part of the reaction tubes 1A, 1b and 1C, the peripheral surface of which comes into contact with the plate 9, which is located in the middle part of the pipe.

The raw material gas Rg is served in the shell 2 through the inlet 4A for the raw gas and to obtain the reaction product is carried out successively with the passage of gas into the reaction tubes 1A, 1b and 1C.

For example, propylene or isobutylene is served in the form of a gas, a mixed gas containing molecular oxygen, it is converted to (meth)acrolein in the lower part, which is then oxidized in the upper part, forming the (meth)acrylic acid.

In Fig. 6 number 9 shows a plate located in the middle part of the pipe, at number 10 shows three heat shield, zakreplena is below the bottom surface of the plate 10, installed in the middle part of the pipe, by means of spacer rods 13. Under the plate 9, is installed in the middle part of the pipe, there are two or three of the heat shield 10, as shown in this figure, attributed from each other by not more than 100 mm, which created space 12 with a complete lack of flow, even if they are filled with fluid Hm₁or Hm₂. Accordingly, it is preferable that the space was created by the insulation effect.

Heat shields 10 are attached to the plate 9, is installed in the middle part of the pipe, with the next target. As shown in Fig. 5, when the adjustable temperature difference between the heating medium Hm₁supplied to the lower part of the shell 2, and the heat medium Hm₂supplied to the upper part exceeds 100°With, you can not neglect the heat transfer from the hotter fluid less hot coolant, which resulted in the accurate regulation of the reaction temperature of the catalyst in the direction of lower temperature can be lowered. In this case it is necessary to provide thermal insulation to prevent heat transfer above and/or below the plate 9, is installed in the middle part of the pipe.

In Novotrubny the reactor used for the catalytic oxidation in the vapor phase, as the raw material gas Rg for Khujand the exercise of reactions serves gas mixture, containing propylene or isobutylene and/or (meth)acrolein, mixed with the gas or vapor containing molecular oxygen.

The concentration of propylene or isobutylene is from 3 to 10 vol.%, oxygen from 1.5 to 2.5 (molar ratio) and a pair of from 0.8 to 2 (molar ratio) to the number of propylene or isobutylene.

Fed to the reactor raw material gas Rg is divided into two streams, passing in the appropriate reaction tubes 1A, 1b and 1C, and the passage in the reaction pipe, he reacts in the presence contained in the oxidation catalyst. However, the distribution of the raw material gas Rg on the appropriate reaction tubes are influenced, for example, the number or density bookmarks catalyst in the reaction tubes. Such quantities of bookmarks or density bookmarks catalyst ask during the operation of laying the catalyst in the reaction tubes. Thus, it is very important to evenly lay the catalyst in the respective reaction tubes.

For uniform bookmarks catalyst can be used a method of providing a constant density bookmarks by controlling the uniformity of weight of catalyst used in the respective reaction tubes, or by controlling so that the time the bookmark was the same.

The raw material gas Rg coming in soo the appropriate reaction tubes 1A, 1b and 1C, is first heated by passing through a layer of inert substances, laid down in each of the input part, to achieve the temperature of the beginning of the reaction.

Raw material (propylene or isobutylene) is oxidized in the presence of a catalyst contained as the next layer in each reaction tube, and the temperature is further improved by the heat of reaction.

The intensity of the response is greatest in the inlet part of the catalyst layer, and if it exceeds the intensity of the heat the heat medium Hm, the generated heat of reaction will raise the temperature, which can lead to the formation of sites of local overheating. The most likely is the formation of local overheating at a distance of from 300 to 1000 mm from the inputs of the reaction tubes 1A, 1b and 1C.

Accordingly, the efficiency of extraction of heat by the flow of coolant Hm most important within 1000 mm from the inputs of the reaction tubes 1A, 1b and 1C. If the amount of generated heat here reaction exceeds the ability of Hm carrier to extract heat from the peripheral surface of the reaction tube, the temperature of the raw material gas Rg will continue to grow, resulting in the amount of heat generated by the reaction will continue to increase, and, finally, will be uncontrollable reaction. Thus, the temperature of the catalyst can the t to exceed the maximum allowable value, and the catalyst may be subjected to qualitative changes, which may occur poisoning or destruction.

For example, in respect of the reactor preliminary stage to receive acrolein by the oxidation of propylene gas containing molecular oxygen, the temperature of the heat medium Hm is from 250 to 350°and the maximum allowable temperature to avoid formation of local overheating is from 400 to 500°C.

In addition, in relation to the subsequent reactor stage for obtaining acrylic acid by oxidation of acrolein gas containing molecular oxygen, the temperature of the heat medium Hm is from 200 to 300°and the maximum allowable temperature to avoid formation of local overheating is 300 to 400°C.

As Hm carrier, which flows in the shell 2, i.e. around the peripheral surface of the reaction tubes 1A, 1b and 1C, are widely used nitrate, which is a mixture of nitrates, but as the heat can also be used phenyl ether organic liquid system.

Heat recovery is performed on the outer peripheral surfaces of the reaction tubes 1A, 1b and 1C when passing them in the coolant flow Hm. However, in the case of coolant Hm, postupayushih the ring on the pipe 3A in the shell 2, there are locations where the fluid passes from the outer periphery of the shell 2 to the Central part, and the location where the flow direction changes to the opposite in the Central part, and it was found that the effect of heat differs in the relevant locations.

When the direction of flow of the heat medium Hm perpendicular to the axis of the reaction tube, the heat transfer coefficient ranges from 1000 to 2000 W/m²°C. However, when the flow direction is not perpendicular to the axis, he is different in accordance with the flow rate or differential flow up or flow down. However, even if the coolant using the nitrate, the heat transfer coefficient is usually at most 100 to 300 W/m²°C.

On the other hand, the coefficient of heat transfer layers of catalyst in the reaction tubes 1A, 1b and 1C, of course, depends on the flow rate of the raw material gas Rg. However, it is about 100 W/m²°whereby it is evident that he does not change in accordance with the traditional knowledge that the regulation of heat flow carried out in the gas phase in the pipes.

In particular, when the flow of coolant Hm perpendicular to the axis of the reaction tubes 1A, 1b and 1C, thermal resistance of the external periphery of the pipe is from 1/10 to 1/20 from thermal resistance of the reaction is ruby-side gas Rg. Even if the coolant flow Hm is changed, such change will not have a significant influence on the overall thermal resistance.

However, when nitrate is parallel to the axes of the tubes, the heat transfer coefficients on the inner and outer surfaces of the reaction tubes 1A, 1b and 1C are almost the same, whereby the influence of flow on the outer periphery of the pipe to the heat recovery efficiency significantly. Namely, when thermal resistance of the external periphery of the pipe is 100 W/m²°C, total heat transfer coefficient is half of this value, resulting in a change half thermal resistance of the outer periphery of the pipe has a decisive influence on the overall heat transfer coefficient.

When the reaction is carried out, you need to carefully monitor the difference between the coefficients of heat transfer.

The reaction tube 1b is held by all units (usually three plates) and has a great overall heat transfer coefficient and a small maximum temperature of the catalyst when the temperature distribution in the direction of the axis of the reaction tube, which can be thought of as the average across the shell 2.

In addition, the reaction tubes, which are in the position where the heat medium Hm reverses the direction of movement, are the reaction tube 1C SV is free from one baffle, or the reaction tube 1A is free from the two deflectors.

When the amount of the raw material gas Rg fed to the reaction tubes 1A, 1b and 1C, increase or maintain a high temperature to obtain a high degree of conversion, the maximum temperature of the reaction tube has a tendency to increase, which may lead to the formation of areas of local overheating, which will increase the possibility of catalyst poisoning or an uncontrollable reaction.

In this case, it is necessary to strictly control the temperature of the heat medium Hm. Many of the reaction tubes 1A or 1C placed many thermometers 11, and regulate the temperature of the heat medium Hm in tracking the temperature of formation of sites of local overheating in the respective reaction tubes. Thus, the temperature of the heat medium Hm is strictly regulate to obtain the proper temperature, and can therefore be obtained the desired result of the reaction and, in addition, it is possible to prevent, for example, the poisoning of the catalyst and to carry out continuous operation over an extended period of time.

When the maximum temperature of the reaction tubes 1A is close to the limit temperature, the temperature of the heat medium Hm can be reduced. However, in the case of the reaction tube 1C, a situation may arise when the temperature in the part farther along the stream about a point showing the maximum temperature can rise. Thus, it cannot be neglected by the current control.

When the conversion by the reaction below a preset value, it is necessary to increase the temperature of the heat medium Hm. However, even in this case, it is important to monitor the maximum temperature of the reaction tube, so that it does not exceed the temperature limit. In addition, the maximum temperature of the reaction tube or the point showing the maximum temperature of the reaction tube, can sometimes change when you increase or decrease the amount fed to the shell 2 of the raw gas in a gas mixture of propylene or isobutylene and a gas containing molecular oxygen, or a similar mixture.

In addition, more preferably, thermometers 11 were placed in many reaction tubes 1b and the temperature of the heat medium Hm regulated while monitoring temperatures of the catalyst layers in the reaction tubes.

The maximum temperature of the reaction tubes 1b, which constitute the majority of the reaction tubes, measure and compare with the maximum temperature of the reaction tubes 1A or 1C in other areas, so you can get a higher response.

The difference between the maximum medium temperature (middle C is achene maximum temperature of each reaction tube) reaction tubes in the relevant areas should be preferably in the range of 30° C, more preferably in the range of 20°S, and most preferably in the range of 15°C. If the difference is too large, the performance of the reaction will decrease, which is undesirable.

The number of the reaction tubes 1A, 1b and 1C, in which are placed thermometer 11, in the relevant areas is at least 1, preferably from 3 to 5. If the number of filled thermometers less, a situation may arise when the abnormality maximum temperature of the reaction tube can not be detected, even if there is unevenness of the temperature of the heat medium Hm, supplied in the annular pipe 3A of the shell 2.

In addition, under the above area means the area of concentration of the reaction tubes, which pass through the opening or space of one baffle and connected with one baffle and held them.

Types of liners for changing the direction of flow of the heat medium Hm, passing in the shell 2, or to prevent bypass flow of the heat medium Hm is not limited to specific types. However, you can use segmental baffles or all of the deflectors shown in Fig. 2 or 3, and as is well known, widely used round the vents.

The square hole in the center of the deflector 6A is 5 to 50%, preferably from 10 to 30%, square the internal cross-section of the shell 2.

The area of the free space formed between the outer peripheral edge of the baffle 6b and the inner wall of the shell 2, is from 5 to 50%, preferably from 10 to 30%, the internal cross-section area of the shell 2.

If the aspect ratio holes and space deflectors 6A and 6b are too small, the flow path of the heat medium Hm is long, the pressure loss between the circular pipes 3A and 3b will be increased and it will be necessary to increase the capacity of the circulation pump 7. On the other hand, if the proportion is too large, will increase the number of the reaction tubes 1A and 1C.

The spacing of the respective units (the distance between the deflectors 6A and 6b; the distance between the deflector 6A and the upper plate 5A for fastening pipes; the distance between the deflector 6A and the lower plate 5b for fastening pipes) is usually set at a regular interval. However, there may be no need to set the intervals provided that you can provide the necessary coolant flow Hm, determined by the heat of oxidation reaction generated in the reaction tube, and can achieve low loss of pressure fluid.

It is necessary to exclude the situation when the point of maximum temperature in the temperature distribution in the reaction tubes 1A, 1b and 1C coincided with the location of the deflector 6A, 6b Il is 6A. Near the surface of each deflector coolant flow decreases, and the heat transfer coefficient will be low. Accordingly, if the point of maximum temperature of the reaction tube coincides with the deflector becomes a high probability that formed the plot of local overheating.

In the shell 2 inside the reaction tubes 1A, 1b and 1C, containing the oxidation catalyst is a gas phase, the maximum linear speed of the raw gas is limited by the catalyst, resulting in the heat transfer coefficient in the appropriate reaction tubes will be low, and the process flow control becomes the regulatory process heat transfer. Accordingly, it is very important the size of the inner diameter of the reaction tubes.

The inner diameter of the reaction tubes 1A, 1b and 1C affects the amount of heat of reaction and particle diameter of the catalyst in the tubes. However, usually select the internal diameter of from 10 to 50 mm, the preferred diameter of from 20 to 30 mm When the inner diameter of the respective reaction tubes is too small will reduce the weight inherent in them of a catalyst will increase the number of reaction tubes for the desired amount of catalyst, resulting in the shell 2 will be large.

On the other hand, if the inner dia is the ETP of the reaction tube is too large, the area of contact of the catalyst with the surface of the reaction tube will be small for the required quantities of heat, resulting in heat transfer efficiency to extract the heat of reaction will be reduced.

As thermometer 11 is placed in the reaction tube, use the column thermometer, in which a multitude of thermocouples, RTD sensors, etc. are closed by the outer tube (termporarily), or thermometer, in which the probe can be moved in the shell.

You want thermometer 11 was set in position, aligned with the pipe axis, and at its outer tube are protrusions, whereby the distance from thermometer to the inner wall of the pipe is kept constant and such that thermometer was aligned with the pipe axis.

Preferably, the axis of the reaction tube and the Central axis of thermometer 11 were combined. In addition, it is preferable that the protrusions formed on thermometer 11, were located in front of and behind the point of maximum temperature in the catalyst bed.

As the outer tube (termporarily) thermometer 11 use the tube diameter, comprising at most 15 mm in Addition, with regard to the inner diameter of the reaction tube, the distance to the inner wall of the reaction tube must be at least two times is larger than the diameter of the catalyst particles. If the diameter of the catalyst particles is 5 mm and the inner diameter of the reaction tube is 30 mm, the diameter of the outer tube of thermometer 11 will be at most 10 mm

If the density bookmarks catalyst in the reaction tube in which is placed thermometer 11 is different from the density in another reaction tube, accurate temperature measurement is impossible. Accordingly, the outer diameter of thermometer 11 preferably should be at most 6 mm, more preferably from 2 to 4 mm.

The present invention is based on the adoption of measures to meet the situation through the analysis of flow and heat transfer coefficient of the heat medium Hm and provides for the existence of a part having a low coefficient of heat transfer, the relevant parts of the cross section of the shell 2. However, with respect to the reaction tube located in a part having a low coefficient of heat transfer, in particular in relation to the reaction tubes 1A and the reaction tube near her area, having a very low coefficient of heat transfer is in the open part of the deflector (all the open part in the center of a circular vent in the center section of the shell 2 or close to it. This area is in the center or near the center of the open part of the baffle 6A. Thus, it is not recommended to place the reaction tube is the area, the relevant part having a ratio to the cross-sectional area of the shell, comprising from 0.5 to 5%. If such part is less than 0.5%is required to set the flow rate of the heat medium Hm, which is at least twice that the heat transfer coefficient was at least at the minimum level required value, resulting in a need to increase the capacity of the circulation pump 7.

However, if the area where it is impossible to place the reaction tube exceeds 5%, it is necessary too to increase the diameter of the shell 2 for the location of the required number of reaction tubes.

In relation to the reaction tubes 1A, which are not held by the deflector 6A, it is preferable not to place them in the range from 30 to 80% of the width of the open part of the deflector 6A (in the case of a radial deflector shown in Fig. 2) or the diameter of the open part of the baffle 6A (in the case of a circular baffle shown in Fig. 3).

In Fig. 1-5 arrows show the flow of coolant Hm in the shell 2, upward. However, the present invention can be applied also in the case when the flow direction is opposite.

When to set the direction of the circulating flow of the heat medium Hm, it is necessary to pay due attention to the exclusion of such phenomena as the inclusion in the stream of carrier gas, which may stavitsa in the upper parts of the shell 2 and the circulation pump 7, in particular an inert gas, such as nitrogen.

In the case where the heat medium Hm is held up, as shown in Fig. 1, if the gas is included in the coolant in the upper part of the circulating pump 7, the circulation pump can cause cavitation phenomenon, and in the worst case, the pump may be damaged. In another case, the phenomenon of inclusion of gas will occur also in the upper part of the casing 2, and in the upper part of the casing 2 will be a limiting part of the gas phase, resulting in the upper part of the reaction tube located in the gas containment part will not cool the coolant Hm.

As measures to prevent stagnation of gas you need to create a line for venting gas to replace the gas in the gas layer coolant Hm. To this end, the pressure of the fluid in the pipe 8A coolant should be increased, and the exhaust pipe 8b to have coolant in the most upper position to increase the pressure in the shell 2. Exhaust pipe 8b coolant should be placed higher than the top plate 5A for mounting pipes.

The flow of the raw material gas Rg in the reaction tubes 1A, 1b and 1C can be directed up or down. However, with respect to the coolant flow preferred parallel stream.

The calorific value in the reaction tubes 1A, 1b and 1C Naib has the greater magnitude at the inlet pipe, and the location of the formation of local overheating is often located at a distance of from 300 to 1000 mm from the entrance along the pipe axis.

In connection with the deflectors, the location of local overheating is often located in the area between the top plate 5A for mounting pipe or the bottom plate 5b for fastening pipes and baffle 6A. Formation of sites of local overheating can be easily controlled by coolant Hm, having adjustable temperature, directly to the location of the axis of the reaction tubes 1A, 1b and 1C, the respective points of maximum temperature of the reaction tubes. Accordingly, it is preferable that the macroscopic flow direction of the heat medium Hm and the direction of flow of the raw material gas Rg coincide, namely, parallel threads.

The amount of heat transfer, namely, the value of the heat of reaction can be calculated as follows: coefficient of heat transfer is × area of heat transfer is × (the temperature of the catalyst layer temperature of the coolant). Accordingly, a method of reducing the magnitude of the heat of reaction per unit surface area (square heat transfer) reaction tubes effective to reduce the maximum temperature of the reaction tube.

To equalize the amount of heating by the heat of reaction in one reaction tube bookmark devout, at least two types of catalyst layers having different activity. Preferably, on the input side was laid a layer of catalyst having less activity, and the many layers of the catalyst is put into the reaction tube so that the layers of the catalyst having a higher activity began after the peak in the temperature distribution.

As a way of regulating the activity of the catalyst layer can, for example, to use the method of application of the catalyst, the activity of which change by regulating the composition of the catalyst, or a method of regulating the activity by mixing the catalyst particles with an inert particles to dilute the catalyst.

The layer of catalyst having a greater proportion of inert particles (ratio of catalyst particles in the mixed particle: the proportion of dilution), lay in the front part of the reaction tubes 1A, 1b and 1C, and a layer of catalyst having a small or zero the proportion of dilution, lay further along the flow in the reaction tube. The ratio of dilution will vary depending on the type of catalyst. However, in many cases, the dilution ratio for the earlier stage is from 0.3 to 0.7. Preferably for a later stage we use the proportion of dilution, comprising from 0.5 to 1.0. When is Anenii activity or dilution of the catalyst is usually applied two or three stages.

The ratio of dilution of the catalyst incorporated in the reaction tubes 1A, 1b and 1C, may not be the same in all pipes. For example, the maximum temperature of the reaction tubes 1A high, resulting in the possibility of catalyst poisoning is high. To exclude such poisoning is possible to reduce the proportion of dilution for earlier stage and, conversely, to increase the proportion of dilution for a later stage.

If the degree of conversion of the reaction in the appropriate reaction tubes are different, the overall conversion or the performance of the reactor is thus degraded. For this reason, it is preferable that the respective reaction tubes were prepared to obtain the same conversion, even if the dilution ratio is changed.

The present invention can be implemented using mnogotranshevogo reactor for the oxidation of propylene or isobutylene gas containing molecular oxygen, or mnogotranshevogo reactor for oxidation of (meth)acrolein gas containing molecular oxygen, to obtain a (meth)acrylic acid. As the catalyst used for the oxidation of propylene, preferably using multi-component composite metal oxide mainly consisting of compounds of the type Mo-Bi, and as a catalyst for obtaining the acrylic is Oh acid by oxidation of acrolein preferably use composite oxide, mainly consisting of compounds of the type Mo-V.

Propylene or isobutylene oxidized in two stages, whereby it is possible to use two Novotrubny reactor, and the corresponding reactors can lay different catalysts. However, as shown in Fig. 5, the present invention can be realized in the case when the shell one reactor is divided at least into two compartments by a plate located in the middle part of the pipe, and accordingly can be based on different catalysts for production of (meth)acrylic acid in a single reactor.

Examples

Example 1

For the implementation of the oxidation reaction of propylene as the catalyst (A) have been prepared in accordance with conventional methods for producing powder catalysts catalyst consisting of (atomic ratio) Mo=12, Bi=5, Ni=3, Co=2, Fe=0,4, Na=0.2, A / B=0,4, K=0,1, Si=24 and=x (contents x of oxygen is the value determined by oxidation of the corresponding metals; this applies to the following), as well as the catalyst (C) a catalyst consisting from (atomic ratio) Mo=35, V=7, Sb=100, Ni=43, Nb=3, Cu=9, Si=20 and=H. From powder catalyst were respectively formed, and used the ring catalysts having an external diameter of 5 mm, an inner diameter of 2 mm, and height, component 4 mm was used in the IAOD Novotrubny reactor with an inner diameter of the shell, components of 3500 mm, with 9000 reaction tube made of stainless steel, as shown in Fig. 1, with the reaction tube had a length of $ 3500 mm, an inner diameter of 24 mm and an external diameter of 28 mm, respectively. Reaction tubes were located outside of the circular part with a diameter of 500 mm in the center of the shell.

The baffles were arranged with equal intervals in the order, as are all the deflectors 6A-6b-6A, and the corresponding proportion of the area of the exposed parts of the baffles was 18%. In addition, the deflectors 6A had a diameter of the open part constituting mm, and baffle 6b had a diameter of 3170 mm

In addition, in the shell were located, as shown in Fig. 1, the reaction tube 1A in the amount of 1534 pieces, reaction tubes 1C in the number 1740 pieces, and the rest of the number was the reaction tube 1b.

As Hm carrier used molten nitrate salts, which are a mixture of nitrates, and it was served in the lower part of the shell 2.

As the reaction temperature used, the temperature of the nitrate supplied to the shell 2, as measured by thermometer 14. Moreover, the consumption of nitrate regulated so that the temperature difference between the exit and entrance of the shell 2 was 4°C.

In the respective reaction tubes founded and 1.5 liter of catalyst (a) and in the lower part of the reactor was served raw gas with the concentration of propylene, component 9%, a pressure of 75 kPa.

To the reaction tubes 1A, 1b and 1C were placed thermometers 11 with 10 measurement points in the direction of the axis of each pipe, for measuring the temperature distribution. In each area of the reaction tubes 1A, 1b and 1C were placed on two thermometers (total of six).

To accurately measure the maximum temperature of the respective reaction tubes of the measuring point thermometers 11 were located, respectively, at intervals of 250 mm from the inputs of the reaction tubes to points at a distance of 1500 mm from them and 400mm intervals after a distance of 1500mm. The maximum temperature of the pipes were fixed with the help of these thermometers 11.

When the temperature of the heat medium Hm was set at the level 331°With average values of maximum temperatures of the respective reaction tubes 410°in the reaction tubes 1A, 390°in the reaction tubes 1b and 390°in the reaction tube 1C. In addition, in this case, it was found that the conversion of propylene was 97%, and the yield was 92%.

Example 2

Using the same reactor as in Example 1 was applied to the gas containing molecular oxygen (oxygen concentration, which is 15 vol.%), in the proportion of 35 vol.%, which reacts with the gas at the outlet of the reactor specified in example 1 to obtain acrylic acid.

In testwuide reaction tubes laid 1.2 liters of catalyst (In). The reaction was carried out analogously to Example 1, except that the temperature of the heat medium Hm was set at 275°C.

The average values of the maximum temperatures of the respective reaction tubes was 330°in the reaction tubes 1A, 300°in the reaction tubes 1b and 300°in the reaction tube 1C. In addition, in this case, it was found that the conversion during the reaction was 99%, and the yield was 90.5 per cent when calculating on the basis of propylene.

Example 3

Was used in the same reactor as in Example 1, and the catalyst (a) and annular inert material obtained by forming an inert material (aluminum oxide)were mixed in a 1:1 ratio and placed in reaction tubes from their inputs over 1500 mm In the remaining 1800 mm length of the reaction pipe was laid only the catalyst (A), and in the last 200 mm length were laid aluminum balls are inert in this reaction.

The reaction was carried out as in example 1 except that the temperature was set to 335°C. as thermometers to measure the temperature of the catalyst was used in thermometers, providing measurement at 15 points, and measurement was carried out at intervals of 200 mm

It was determined the temperature distribution of the respective layers of catalysis is ora, and it was found that the catalyst layers had two maximum temperature.

They were identified as primary maximum temperature and the secondary maximum temperature, starting from the inputs of the reaction tubes, and as for the corresponding averages in the reaction tubes 1A primary maximum temperature was 393°and the secondary maximum temperature was 345°With, in the reaction tubes 1b primary maximum temperature was 370°and the secondary maximum temperature was 350°and in the reaction tubes 1C primary maximum temperature was 365°and the secondary maximum temperature was 380°C.

Compared with the case where the catalyst has not been diluted, the temperature of the heat medium Hm was higher on 4°C. However, the corresponding maximum temperature in the catalyst layers were lower by 10-20°even when compared to higher temperatures. Thus, the result showed that it is possible to expect increase of the service life of the catalyst and continuous operation.

In addition, the total production of acrolein and acrylic acid derived from propylene, made of 92.5%.

Comparative example 1

The reaction was carried out as in example 2, except that thermometers were not placed in the reaction trubia and 1C, but the same thermometers, as in example 1, was placed in reaction tubes 1b, United with all the baffles and with good efficiency at removing heat.

To obtain a level conversion acrolein comprising from 99% to 99.5%, the temperature of the heat medium Hm at the inlet was increased from 275°280°C, resulting in a maximum value in the temperature distribution of the catalyst in the reaction tubes 1b amounted to 310°C.

Through analysis, the resulting reaction gas was measured conversion rates, which were found to have dropped to 97.9%. After this work was continued, with the conversion gradually decreased. The temperature of the heat medium Hm at the entrance of the reactor was again increased by 2°to the level 282°C, resulting in the conversion of acrolein further reduced.

When the conversion acrolein decreased to 95%, the reaction was stopped to check the status of the catalyst in the reaction tubes. In the reaction tubes 1b and 1C deviations of the catalyst from the norm is not detected. However, the number of the reaction tubes 1A, in particular approximately 350 of the reaction tubes 1A, located near the center of the reactor, it was found that the catalyst significantly poisoned, its form has changed, and he lost catalytic activity. Presumably, the catalyst was subjected to the I to the influence of high temperature, comprised of at least 400°C.

Industrial application

In the process of catalytic oxidation in the vapor phase using mnogotranshevogo reactor according to the present invention measures the temperature inside the reaction tubes containing embedded in them the catalyst and located in the shell of the reactor, and on the basis of this temperature control the temperature and flow rate of the coolant supplied into the shell, resulting in obtaining (meth)acrylic acid, etc. from propylene or isobutylene is possible to prevent uncontrollable reaction or early poisoning of the catalyst, and it becomes possible continuous production with high yield over a long period of time.

1. Method of catalytic oxidation in the vapor phase, in which the raw gas is fed to the oxidation reaction tubes mnogotranshevogo reactor, which is equipped with a number located in the shell of the reactor, the reaction tubes, which are incorporated in the catalyst, and plenty of vents for changing the direction of flow of the coolant supplied into the shell, characterized in that the measured temperature of the catalyst incorporated in the reaction tube, which is not connected, at least one deflector, based on the measured temperature of the catalyst regulate temperature and coolant flow, served in the shell.

2. The method according to claim 1, in which the temperature of the catalyst is measured in 2-20 points in the direction along the axis of the reaction tube.

3. The method according to claim 1, in which the temperature of the catalyst is measured using a multipoint thermocouple.

4. The method according to claim 1, in which the flow of raw gas, which takes place in the reaction tube, and the macroscopic flow of the heat carrier, which is held in the shell, move in the same direction.

5. The method according to claim 1, wherein in the reaction pipe laying multiple layers of catalyst, which have different activity.

6. The method according to claim 1, in which the raw material gas as the oxidizable substance contains propylene, isobutylene or (meth)acrolein.

7. Method of catalytic oxidation in the vapor phase, in which the raw gas is fed to the oxidation reaction tubes mnogotranshevogo reactor, which is equipped with a number located in the shell of the reactor, the reaction tubes, which are incorporated in the catalyst, and plenty of vents for changing the direction of flow of the coolant supplied into the shell, characterized in that the measured temperature of the catalyst incorporated in the reaction tube, which is not connected, at least one baffle, and the temperature of the catalyst incorporated in the reaction tube, which is connected with all the vents, and is again measured temperature of the catalyst regulate the temperature and flow, served in the shell.

8. The method according to claim 7, in which the temperature of the catalyst is measured in 2-20 points in the direction along the axis of the reaction tube.

9. The method according to claim 7, in which the temperature of the catalyst is measured using a multipoint thermocouple.

10. The method according to claim 7, in which the flow of raw gas, which takes place in the reaction tube, and the macroscopic flow of the heat carrier, which is held in the shell, move in the same direction.

11. The method according to claim 7, in which in the reaction pipe laying multiple layers of catalyst, which have different activity.

12. The method according to claim 7, in which the raw material gas as the oxidizable substance contains propylene, isobutylene or (meth)acrolein.