Reactor for dehydrogenation of paraffin hydrocarbons, c3-c5

 

(57) Abstract:

The invention relates to the field of petrochemicals, in particular for reactors for dehydrogenation of paraffin hydrocarbons. Reactor for dehydrogenation of paraffin hydrocarbons, C3-C5fluidized bed of fine-grained catalyst contains a vertical cylindrical casing, the outlet of input materials and output contact of the gas input and output of the circulating catalyst Stripping section, a distributor of raw materials over it and lattice separating the fluidized bed of the catalyst on the partition. Lattice have the free section, increasing the height of the reactor. The lower grille has a free section that constitutes 10-30% of the cross-section of the casing, and the upper 20-60%. The technical result is an increase in the yield of olefin due to the efficiency of the reactor. 10 C.p. f-crystals, 5 Il., table 2.

The present invention relates to the field of petrochemicals, in particular for reactors obtain olefinic hydrocarbon, C3-C5the dehydrogenation of the corresponding paraffin hydrocarbons used in the future to obtain the basic monomers of the IC, as well as in the production of polypropylene, methyltrichlorosilane ether, etc.

Known reactor for dehydr the military industrial methods for the synthesis of butadiene". Analytical comparative reviews Tsniiteneftehim, series Production of synthetic rubbers", M., 1967, S. 81).

The movement of the coarse catalyst layer of the reactor, as well as between the reactor and regenerator is ensured by mechanical conveyors.

The disadvantage of this reactor design is the complexity and the inability to build more reactors performance difficulties in the organization of movement of coarse catalyst system in the reactor-regenerator. In addition, the resulting movement and abrasion of catalyst catalyst dust permanently carried away from the reactor system with the exhaust gases, which leads to environmental pollution pulverized waste catalyst.

The closest in technical essence and the achieved result to the present invention is a reactor for the dehydrogenation of paraffin hydrocarbons with a fluidized bed of fine-grained catalyst comprising a vertical cylindrical casing, the outlet of input raw materials and contact the gas input and output circulating through the regenerator catalyst (catalyst circulation uses a simple system of pneumatic transport), the set of lattice perforated type, separating the fluidized bed of the catalyst on the partition ("Industry synthetic rubber", Moscow, NIITA - Neftekhim, 1968, N 2, p. 8, P. K. Mikhailov, A. N. Bushin "Joint dehydrogenation of butane and isopentane in a fluidized bed of fine-grained catalyst").

However, this reactor has a partitioning of the lattice with the same free cross-section. This leads to an increase in height of the reactor linear gas velocity through the holes in the grids (in the region from 0.5 to 2.0 m/s, starting from the bottom of the lattice to the top) due to the fact that the reaction of dehydrogenation are going to increase, and the temperature of the fluidized bed partitioned reactor increases from the bottom of the lattice to the top. However, only the upper grille has a maximum speed of gas holes and works in the regime close to the preferred mode zahlebyvayas, in counterflow to the movement of gas and catalyst in the holes. All other lattice with reduced gas velocity in the holes, ineffective due to the increased back-mixing of catalyst and gas and deterioration of mass transfer on these lattices.

Used grille perforated type, which is a flat plate with holes, are not what prostranstve between the holes.

These lattices are characterized by a high reverse mixing of catalyst and gas, which worsens the conditions of achievement of the mode displacement during movement of the catalyst and the gas in the reactor.

In addition, in large reactors (with a diameter of reactors 5 m and above) there is the problem of sewage flow, when the gas tends to go in the center of the reactor, and the catalyst on the periphery in the parietal area.

At the same time there is an uneven distribution of the catalyst in sections of the reactor (the amount of the catalyst decreases from the section to the top), mainly due to a corresponding increase in the heights "gas" pillow" under the grates and changes in the concentration of catalyst in the fluidized layer, depending on the height of the layer that forms a non-optimal temperature profile along the height of the reactor.

Used in the known reactor distributor of raw materials, manufactured in the camera view conical shape with a flat distribution plate with the holes in the base of the cone, located in the Central part of the cross section of the cone reactor is stagnant zones in the space between the holes in the distribution plate and the annular space between the distribution of ka the spaces.

In this work a Stripping section in the known reactor and the distribution of gas flow over the cross section of the reactor is not effective enough.

In addition, the height of the fluidized bed of catalyst in the low temperature zone between the distributor and the lower partitioning the lattice (where it is removed in the regenerator at low temperature circulating catalyst), as well as in the high temperature zone between the upper grid and the level of the fluidized bed reactor (which is fed from the regenerator circulating superheated catalyst) in a known reactor excessively large (up to 2.5-3 m for industrial reactors of large capacity), which determines the low level of mass transfer in these areas. The dependence of the interfacial exchange from the height of the fluidized bed above the distributor and partitioning grids is that the scope of gas streams in areas adjacent to the distributors and the grids, the mass transfer maximum, and then decreases with the height of the fluidized bed, mainly due to the increase of the size of gas bubbles (j.ATS "foundations of mechanics of fluidization with applications", Moscow, "Mir", 1986, page 157). At this altitude low temperature and high temperature zones are mainly required the RA in these areas.

Heating the substrate before feeding it into the boiling layer in the known reactor is carried out in furnaces by fire heating the raw material coils combustion. However, a large amount of flue gases directed from the furnace to the atmosphere, creates significant environmental problems.

These defects determine the relatively low rates of dehydrogenation of paraffin hydrocarbons outputs of olefins on missing and decomposed raw material known in the reactor.

The present invention is to increase yields of olefins due to more efficient reactor operation.

To solve this problem is proposed reactor for dehydrogenation of paraffin hydrocarbons, C3-C5fluidized bed of fine-grained catalyst comprising a vertical cylindrical casing, the outlet of input materials and output contact of the gas input and output of the circulating catalyst Stripping section, a distributor of raw materials over it and lattice separating the fluidized bed of the catalyst on the partition. Lattice have the free section, increasing the height of the reactor, while the lower grille has a free section that constitutes 10-30% of the cross-section of the body, and faiths and/or pipes;

b) double-row lattice consisting of two slotted grates installed one above the other so that the slit gratings are arranged in parallel and offset in the horizontal plane to the complete overlap of the slits upstream of the grille cloth and downstream to form between the lattices of the slot gap width less than the width of the slit gratings;

C) combined lattice, the peripheral part of which is single, and the Central part, which covers an area equal to 10-50% of the cross-section of the reactor row.

Lattice in the reactor can be installed in groups of 2-7 lattices in the group. When this grating in each group have the same free section.

Preferred options the design of the reactor:

- the distance from the bottom of the lattice to the distributor of raw materials is from 0.8 to 3.0 height of the lower section of the fluidized bed of catalyst;

distance from top of grating to the level of the fluidized bed of catalyst is from 0.8 to 3.0 height of the lower section of the fluidized bed of catalyst;

as a distributor of raw materials to the distance from the Stripping section comprising 0,5-3,0 height of the lower section of the fluidized bed of catalyst, a tubular distributor, supplying the second section;

- over distributor of raw materials to the distance of 0,5 - 2,0 height of the lower section of the fluidized bed of catalyst, is an additional tubular distributor of raw material, equipped with nozzles directed downward and covers all of the cross-section of the reactor;

the nozzles located on the tubular distributors of raw materials, have inlets with a diameter smaller than a weekend;

- above the upper grate fluidized bed of catalyst installed heat exchanger to superheat the raw materials before entering it into the reactor.

In the proposed reactor used gratings failure type, providing a counter-current movement of the gas phase and catalyst. The preferred velocity of the gas in the holes of the grating is in the range of 1.5-3.0 m/s and is determined by the maximum approximation to the mode zahlebyvayas each lattice as a catalyst, moving prototechno to gas, "freeze" on lattices and its falling through the holes quantitatively approaching the magnitude of the directed circulation of the catalyst between the reactor and regenerator.

The optimal number of lattices in the reactor 8-14 units of the Lattice can be located at the same distance from each other, so is a great location slots - in Cordova direction, and the lattice is better to install in the reactor so that the direction of the slits upstream grid deployed on the 90oon the direction of the slits downstream of the grid.

Radial direction of the slits is less preferable, as it promotes the "contraction" of the gas stream in the Central part of the reactor.

The change in the free cross section of the grating height of the reactor can be directly proportional dependence, and better to reflect changes in the conversion of hydrocarbons and, respectively, the volumes of gas at the height of the fluidized bed.

As the tubular distributor of raw materials can be used such as a tubular dispenser collector type with cylindrical nozzles-nozzle or dispenser type "squirrel cage" with the ring elements of the pipe.

In Fig. 1 shows a diagram of the proposed reactor. The reactor has a housing 1, piping, and connections input 2 and output 3 catalyst, raw inlet 4 and the contact strip 6. The reactor also contains a distributor of raw materials 6 and additional dispenser 7. Fluidized bed of catalyst in the reactor 8 is partitioned grating (lower grille - 9, the upper reseparating zone 14 and the high-temperature zone 15, heat exchanger is a coil 16, 17 cyclones with filespacename struts 18, Teploobmennik-exchanger 19.

In the circuit shown, the raw material is heated by one thread sequentially in the heat exchanger - the heat exchanger 19 and the coil 16, however, there is a parallel substrate is heated in two streams, one of which passes through the heat exchanger-recuperator, and the other through the coil, with subsequent mixing of these flows.

It is also possible sequential heating of the raw material by one thread at first in the coil 16, and then in the heat exchanger-the heat exchanger 19 or other heaters.

In Fig. 2 shows a possible construction of the tubular distributor of raw materials, and Fig.3 - additional tubular dispenser. The drawings show a two-piece valves, although the dispenser may be a different number of sections. Each section has a header 1 and connected distribution pipe 2 circular or straight configuration. Distribution pipe provided with a nozzle 3, pointing downwards.

Represented in the drawings, the pipes have input metering hole 4 and the adjacent expansion chamber 5 conical or cylindrical shape with output the s-section of some fragments of designs single and double row of gratings, with the free section in the form of cracks 1, the canvas grid 2, is made of parts and/or pipes, slotted gaps 3.

In Fig. 5 presents the combined lattice, the peripheral portion 1 which is made as a single row, and the Central part 2 - how-row.

The reactor operates in the following way (see Fig.1).

The vaporized paraffin hydrocarbons (raw materials) are fed into the reactor through the pipeline and the pipe 4. A pair of raw material is preheated in the heat exchanger-recuperator 19 warm contact of gas overheat in the coil 16 and sent to the valves 6 and 7. In the Stripping section 12 through the pipeline 13 is supplied inert gas to the Stripping of hydrocarbons from the exhaust of the reactor catalyst. In the low temperature zone of the fluidized bed 14 raw material is mixed with the rising of the Stripping section 12 gases bog and leads of the fluidized layer of the catalyst, passing partitioning grilles and high-temperature area of 15, then getting in netslave space of the reactor.

Endothermic dehydrogenation of paraffin hydrocarbons requires heat. Heat input is provided by circulating through the regenerator catalyst. Regenerated and PSOne 15 reactor passes fluidized bed reactor prototechno rising pairs of raw materials, and gradually cools down during the endothermic dehydrogenation reaction, and served in the low temperature zone 14, where through the Stripping section 12, through the pipeline and the pipe 3 in splenorenal and restored the form is returned to the regenerator by burning coke oxidation and heating.

Received contact gas after dust removal in installed in nadsloevom space cyclones 17 through the pipe 5, through the heat exchanger-the heat exchanger 19 is sent for recycling extract obtained olefinic hydrocarbons. Caught in the cyclone 17 catalyst is returned by the struts 18 in the high temperature zone of the fluidized bed 15.

Differences in the design of the proposed reactor from the prototype are:

- Increase the free cross-section partitioning grids height of the reactor from 10-30% of the cross section of housing for lower grilles up to 20-60% for the upper grid.

When this is achieved:

- Approximation of all lattices of the reactor to the mode zahlebyvayas with minimal mixing of the catalyst and gas and increased mass transfer on these lattices catalyst.

The lower back is so greater approximation of the mode of the reactor to the ideal mode of displacement.

- More uniform distribution of catalyst in sections of the reactor to ensure a more uniform temperature profile along its height and, thus, more efficient use of the reactor volume from the point of view of optimal allocation of conversion of paraffins height of the reactor.

The value of the free cross-section of the grating is determined by the amount fed to the reactor raw material and depends on the gas velocity in the cross section of the reactor and take speed in the holes in the grates. The reduction of the free cross section of the lower grill below 10%, and below the top 20% leads to performance degradation of the reactor to values, not economically viable and increase the free cross section of the lower grille above 30% and, respectively, above the upper 60% requires an increase in the productivity of the reactor to values, difficult-to-implement technically and limited to the limiting gas velocity in the reactor and its size.

- Set lattices of a certain design.

Use the target gratings made on the basis of the corners and/or pipes, provides pouring with arrays of catalyst during emptying of the reactor.

A two-row grid sharply reduce back mixing by lengthening flow paths in the free section of the lattice and change the direction of these flows.

The use of double-row design, the Central part of the gratings in machines of large diameter reduces sewage flows, because, while remaining permeable to catalyst over the whole cross section, the lattice has a slightly increased resistance in the Central part for the passage of gas, which aligns the flow velocity in the cross section of the reactor. By reducing the area of the Central part of the grating is less than 10% of the cross section of the reactor or increase above 50% is not achieved the required uniform flow of catalyst and gas in the cross section of the reactor.

- Set lattices groups 2-7 gratings with the same free cross-section of gratings in each group.

This arrangement simplifies the manufacture and installation of gratings.

- Installing the valve at a distance of 0.8 to 3.0 height of the lower section of the fluidized bed of catalyst from the bottom of the partitioning grid.

When this happens:

The increase in total mass in the lower low-temperature zone of the reactor between the distributor and the bottom grate, where, thus, insufficient is and the upper grid of the level of the fluidized bed of catalyst at a distance of 0.8 to 3.0 height of the lower section of the fluidized bed of catalyst.

This reduces the time of contact in the high temperature zone above the upper grate, where high temperatures can go non-selective conversion of paraffin hydrocarbons, as well as the decomposition formed in the lower sections of olefins.

The decrease of the distance from the bottom of the lattice to the distributor and from the top of the lattice to the level of the fluidized bed to values of less than 0,8 height of the lower section leads, respectively, to insufficient conversion of paraffins in the lower low-temperature zone of the reactor under the lower grille (lower volume zone is not compensated by increased masomenos in this area) and an increase in non-selective transformations of hydrocarbons in the area above the upper lattice due to exposed areas of the upper grid when the pulsations of the fluidized bed and unacceptable heating of the metal grill, falling on the exposed surface of the superheated catalyst coming from the regenerator.

In the latter case, there has been an increase mixing of the catalyst on the top grates (hit superheated catalyst in the upper section of the reactor due to the impact of a jet injected into the reactor superheated catalyst from the regenerator).

In addition, the reduction outputs of olefins in connection with increasing time of contact in the upper high temperature zone of the reactor.

- Use as a distributor of raw materials tubular dispenser with nozzle pointing downwards, and having in the centre the free section of 0.25-4.00-section Stripping section. Installation of such a dispenser on the distance from the Stripping section comprising 0,5-3,0 height of the lower section of the fluidized bed of catalyst.

- Extra tubular distributor of raw materials at a distance of 0,5-2,0 height of the lower section from the main distributor. The use of this dispenser, equipped with directed down the pipe and overlying all of the cross-section of the reactor vessel.

As a result of use of the last two constructive solutions is eliminating stagnant zones in the area of the distributor, improving the operation of the Stripping section, the improvement of gas distribution over the cross section of the reactor.

Used distributors permeable to circulating catalyst in the annular space. In the space of the fluidized bed above the Central part of the core will distribute the I and helps to change the direction rising from the Stripping section of the gas flow in the radial direction in the cross section of the reactor (in the space under the distributor). In combination with the direction of the nozzles of the distributor down the features of the dispenser allow you to maintain underneath the catalyst in a mobile state. In addition, increased concentration of catalyst above the Stripping section reduces the capture of hydrocarbons in a Stripping section and their breakthrough in the regenerator with the circulating catalyst, where they will be lost.

The lower Central free cross section of the main valve to a value less 0.25 cross section Stripping section, and a shorter distance from the main distribution to the Stripping section and up to an additional distributor to a value of less than 0.5 of the height of the lower section impair the efficiency of the Stripping section. The increase in the Central free cross section of the main distributor above 4 free cross section Stripping section, as well as the increasing distance from the main distribution to the Stripping section and up to an additional distributor, respectively, to values of more than 3 and 2 heights lower section affects the mixing of the catalyst in the zone below the dispenser, causing problems of stagnant zones, and affects the distribution of gas flow over the cross section of the reactor.

- the TRS outputs.

The resulting decrease in the gas velocity at the exit in the fluidized bed reduces erosion of the nozzle and catalyst attrition jets of gas.

- Install over the top bars of the heat exchange device for overheating of the raw materials before entering it into the reactor.

As a result of increasing the degree of approximation to the preferred isothermal operation of the reactor (decrease of the temperature difference across the height of the fluidized bed).

Heat exchange device may be performed, for example, in the form of a coil, through which pass a pair of raw material. Most preferred is the location of the coil in a variant of the technological scheme, when heated vapor of the raw materials used by the heat exchanger-recuperator located on the pipeline output contact of the gas from the reactor. Given the limitations of heat transfer in the heat exchanger - recuperator system "gas-gas, heating the substrate in the specified heat exchanger is insufficient and additional overheating of the raw materials in the upper high temperature zone of the reactor with subsequent supply of superheated material on the lower low-temperature zone of the reactor significantly reduces the temperature difference in height of the fluidized bed. In addition, whic is reamers 1-8.

The test of the proposed reactor was held at polusovetskaya installation by the following technological scheme.

The reactor with a diameter of 0.85 m and a regenerator with a diameter of 1.4 m are parallel. The circulation of the catalyst between the reactor and the regenerator was carried out by pressure via the two U-shaped pipes. The production capacity of the plant raw material was 500 kg/h Raw material prior to feeding into the reactor overheated up to 550oC in the furnace. Regeneration of the catalyst was carried out at a temperature 645-650oC to time 27-30 minutes When the test was used lomography catalyst obtained by impregnation of a microspherical alumina (dcf.=50-70 microns), with Cr content2O320%.

In examples 1-4 were tested reactor prototype grating having the free section in % section housing:

Example 1 - 20

Example 2 - 25

Example 3 - 60

Example 4 - 25

In examples 5-8 were tested the proposed reactor, the free cross-section of gratings which are given in table 1.

Table 2 shows the parameters and indicators dehydrogenation of paraffin hydrocarbons in the reactor in examples 1-8.

In the new reaktorami lattices, increases the uniformity of distribution of the catalyst and the gas in the cross section of the reactor and the operating conditions of the reactor close to the ideal conditions of displacement as the catalyst, and gas, at the same time achieves a more uniform distribution of catalyst, temperature and conversion of hydrocarbons at the height of the reactor with increasing mass transfer in the volume of the fluidized bed increases the reliability and efficiency of the distributor of raw materials and Stripping sections. This increases the yield of olefins, as well as increases the selectivity of the process of dehydrogenation of paraffin hydrocarbons, C3-C5.

1. Reactor for dehydrogenation of paraffin hydrocarbons, C3-C5fluidized bed of fine-grained catalyst comprising a vertical cylindrical casing, the outlet of input materials and output contact of the gas input and output of the circulating catalyst Stripping section, a distributor of raw materials over it and lattice separating the fluidized bed of the catalyst section, wherein the gratings have the free section, increasing the height of the reactor, while the lower grille has a free cross section of 10 - 30% of the cross-section of the shell, and top - 20 - 60%.

2. R the b.

3. The reactor under item 1, characterized in that it contains a double row of the lattice, which consists of two slotted grates installed one above the other so that the slit gratings are arranged in parallel and offset in the horizontal plane to the complete overlap of the slits upstream of the grille cloth and downstream to form between the lattices of the slot gap width less than the width of the slits of the grating.

4. The reactor under item 1, characterized in that it contains a combined lattice, the peripheral part of which is single, and the Central part, which covers an area equal to 10 - 50% of the cross-section of the reactor, two - row.

5. The reactor under item 1, characterized in that the grid is established by groups of 2 to 7 grids, with grid in each group have the same free section.

6. The reactor under item 1, characterized in that the distance from the bottom of the lattice to the distributor of raw materials is from 0.8 to 3.0 height of the lower section of the fluidized bed of catalyst.

7. The reactor under item 1, characterized in that the distance from the top of the lattice to the level of the fluidized bed of catalyst is from 0.8 to 3.0 height of the lower section of the fluidized bed of catalyst.

8. The reactor under item 1, characterized in that pedego catalyst layer, a tubular dispenser with nozzle pointing downwards, and having in the centre the free section of 0.25 - 4.00-section Stripping section.

9. The reactor under item 1, characterized in that the distributor of raw materials to the distance of 0,5 - 2,0 height of the lower section of the fluidized bed of catalyst, is an additional tubular distributor of raw material, equipped with nozzles directed downward and covers all of the cross-section of the reactor vessel.

10. Reactor PP. 8, 9, characterized in that the nozzles have entrance holes with a smaller diameter than the weekend.

11. The reactor under item 1, characterized in that above the upper grate fluidized bed of catalyst installed heat exchanger to superheat the raw materials before entering it into the reactor.

 

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Reactor // 2246345

FIELD: chemical industry, catalytic processes.

SUBSTANCE: the invention presents a reactor for catalytic processes and is dealt with the field of chemical industry and may be used for catalytic processes. The reactor contains: a body; units of input and output for a reaction mixture and products of reactions; units of loading and unloading of a catalyst; a catalyst layer with the groups of the parallel hollow gas-permeable chambers located on it in height in one or several horizontal planes and each of the chambers has a perforated gas-distributing pipe with impenetrable butt connected to the group collector and used for input of additional amount of the reaction mixture. Each of perforated gas-permeable chambers is supplied with the second gas-distributing pipe with impenetrable butt. At that the impenetrable butts of the pipes are located on the opposite sides. The given engineering solution provides uniformity and entirety of agitation of the reaction mixtures.

EFFECT: the invention provides uniformity and entirety of agitation of the reaction mixtures.

5 cl, 4 dwg

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