RU2266781C2 - Horizontal multi-shelved catalytic reactor for heat-stressed processes of chemical synthesis - Google Patents

Abstract

FIELD: chemical engineering; production of reactors for catalytic synthesis.

SUBSTANCE: the invention is pertaining to the field of chemical engineering, predominantly to reactors of catalytic synthesis. The horizontal multi-shelved catalytic reactor consists of a load-bearing plate, a high-pressure cylindrical body with a cover, which may be transported along the axis of the catalytic unit. The reactor has the typical component and the design of components of the catalytic unit, which consists of the sealed cylindrical catalytic containers, the load-bearing support frame and the module-type heat-exchange devices. The load-bearing support frame represents a crosswise section beam cantileverly fixed on the load-bearing support plate. The vertical plane of symmetry of the frame coincides with the longitudinal axis of the high-pressure body, and on the shelves there are catalytic containers installed in two parallel rows. The frame is cantileverly fixed to the load-bearing plate, through which all inlets and outlets are carried out. The plate is upright mounted on the horizontal foundation and the high-pressure body is joined with it. In the module heat-exchange devices there are tracts for passage of the reactionary gases and the heat-transfer medium. The invention ensures improved conditions of the reactor operation, reduction of its overall dimensions and the mass, simplification of the process of manufacture.

EFFECT: the invention ensures improved conditions of the reactor operation, reduction of its overall dimensions and the mass, simplification of the process of manufacture.

2 cl, 6 dwg

Description

The invention relates to the field of chemical engineering, and more specifically, to catalytic synthesis reactors. It is recommended to use it when creating catalytic reactors for the production of various hydrocarbons, alcohols, ethers from synthesis gas at high pressures and temperatures.

The field of preferred use of the invention is reactors with high heat and high synthesis temperatures, such as, for example:

- a reactor for the single-stage synthesis of dimethyl ether (DME) at pressures from 5.0 to 12.0 MPa and temperatures from 250 to 300 ° C;

- a reactor for the synthesis of gasoline from gas-vapor mixtures containing DME, at pressures from 2.0 to 10.0 MPa and temperatures from 320 to 400 ° C.

For the indicated range of parameters, usually catalytic reactors with a vertical packing (columns) are used. A typical circuit design of a vertical synthesis column with water heat exchangers built between the shelves is presented, in particular, in the work: MM Karavaev et al. Synthetic methanol technology. M .: Chemistry, 1984, p. 118, Fig. 3.40.

This is a vertical apparatus, which is a high-pressure housing filled with a nozzle, on which the catalyst is poured onto the grate (shelves). After each shelf with a catalyst are heat exchangers designed to cool the reaction gases (unreacted synthesis gas together with gas-phase synthesis products). As the primary coolant of the heat exchangers, mainly distilled water is used. The primary heat carrier circulates in a closed circuit, transferring the heat received to the secondary heat carrier in external heat exchange devices (heat recovery boilers, etc.).

The disadvantage of the design of the vertical reactor is that when assembling or disassembling it, for example, to replace the catalyst, it is necessary either to remove the nozzle or to lift the power casing. This requires the use of crane equipment with a crane hook height above the ground, at least two times greater than the height of the reactor. It should be noted that the height of the vertical reactors for the synthesis of DME and gasoline reaches 15 ... 25 meters. If the production is located in an area with adverse climatic conditions, it is required to build a high protective building, which increases capital costs.

More serviceability is provided by horizontal reactors. One of these reactors is presented in patent EP No. 0256299 from 02.24.1988. Horizontal quenching reactor for ammonia synthesis. Patent holder - Kellog (USA).

The reactor has a power external case cooled by cold gas, a removable bottom and an internal case in which four shelves with a catalyst are placed. The supply of synthesis gas and the removal of synthesis products are made in the body and bottom, and the cooling of the reaction gases after each shelf with a catalyst is carried out by mixing cold synthesis gas. The disadvantages of the reactor are the limited possibilities of heat removal after each shelf and temperature control of the reaction gases in a wide range.

The closest analogue is a horizontal reactor, presented in patent RU No. 2174869 from 30.06.2000. Gas-phase catalytic shelf reactor for heat-intensive chemical processes. Patent holder - INKS them. A.V. Topchieva.

The reactor consists of horizontal reaction sections docked to a support heat exchange section. The reaction section includes pressurized shelves - baskets with a catalyst mounted on cantilever traverses, and a power casing placed on rollers (carts).

The heat exchange section includes a package of modular heat exchangers, each of which is connected by pipelines to baskets. The reaction gases after each basket are cooled in the corresponding modular heat exchanger and enter the next basket. The power casing on the rollers can be moved along the axis of the reaction section, while providing free access to any of the baskets and other elements of the reaction section for maintenance.

The reactor has the following disadvantages:

(1) the inability to control the heat transfer mode after a separate basket, since it is carried out in a bath with boiling water common to all modular heat exchangers;

(2) the use of the internal cavities of the cantilever traverse as gas ducts of gas heated to a temperature of 400 ° C, which reduces the rigidity and strength of the traverse, requires a significant increase in their mass, limits the number of baskets installed on them;

(3) placing the traverses in a place remote from the axis of the cylindrical power case, which limits their rigidity and strength due to the inability to obtain the necessary height, which significantly affects the moments of resistance and inertia of the cross section of the traverse.

The main objective of the invention is to improve the usability of the reactor. It includes the solution of the following issues:

(1) the ability to control the temperature of the reaction gases after each basket in a wide range;

(2) ease of disassembly and assembly of the reactor during its repair or replacement of the catalyst.

The second objective of the invention is to reduce the size and weight of the reactor. It is solved due to the general layout, as well as reducing the size and weight of the power support frame and modular heat exchangers (MTU).

The third objective of the invention is the simplification of manufacturing technology. The general layout of the reactor, as well as the design of the main elements of the catalyst unit: catalyst baskets, MTU, power support frame, contributes to its solution.

The presented problems are solved in a horizontal multi-shelf catalytic reactor for heat-intense processes of the chemical synthesis of hydrocarbons, alcohols, ethers. It contains a vertical power plate mounted on a horizontal foundation, a cylindrical high-pressure housing with a cover detachable and hermetically sealed with it, the longitudinal axis of which is horizontal. The housing has the ability to move along the longitudinal axis on carts along the foundation site. The reactor also includes a catalyst unit, consisting of a set of catalyst baskets, a power support frame on which baskets are installed, MTUs that provide cooling of the reaction gases with an external heat carrier, and strapping elements. MTU are located in volumes between the catalyst baskets, on the grate grates (shelves) of which a solid catalyst is poured. The differences of the claimed reactor:

- each catalyst basket has the shape of a cylinder, the longitudinal axis of which is vertical, all the baskets are sealed and designed for an external overpressure of up to 1.0 MPa;

- baskets are installed in two parallel rows of 2 ... 10 pieces in each and fixed on the power support frame;

- the power support frame is a cross-shaped beam, consisting of a longitudinal power rib and two support shelves, cantileverly mounted on the power plate, while the vertical plane of symmetry of the frame coincides with the longitudinal axis of the high pressure housing and between the catalyst baskets and the cylindrical housing provide mounting clearance not less than 50 mm;

- through the power plate all inlets and outlets are made;

- each MTU consists of two cylindrical shells coaxially inserted into each other with a gap of 0.5 to 5 mm for the passage of coolant, and an insert with a gap for passage of reaction gases from 0.5 to 5.0 mm is installed in the inner shell, the lateral surface of which there are elements of macro roughness;

- each MTU is mounted on a power support frame and is connected by gas ducts to the outlet of the previous (along the gas) and the entrance of the subsequent basket along the path of the reaction gases, being part of the gas pipeline connecting them.

Figure 1, 2, 3, 4, 5 and 6 presents graphic materials that explain the essence of the invention. Figure 1 shows the main view of the reactor, figure 2 is a longitudinal section aa, figure 3 is a transverse section bb, figure 4 is a section bb MTU, figure 5 and 6 is a perspective view a reactor with a removed pressure vessel and a twin reactor, respectively.

The catalytic reactor consists (see Fig. 1) of a vertical power plate 1, a high-pressure housing 2, a cover 3, and an isator block. The high-pressure housing is mounted on carts 4 and hermetically docked with a vertical power plate and cover using detachable flange connections with seals. The catalytic unit consists of a power support frame 5, cylindrical catalyst baskets 6, MTU 7, strapping gas ducts 8 and 9. Each MTU along the reaction gas path is connected by gas ducts 9 with the output of the previous (along the gas) and the input of the subsequent basket, being part of connecting them gas pipeline. The power support frame is fastened to the power vertical plate by one of its ends in a detachable manner or by welding. In the case of a large overhang of the console (with the number of baskets exceeding 10 pieces), it is possible to use a removable stop 10, with which the frame rests on the high-pressure housing (near its other end). The frame is a cross-shaped beam, consisting of a power rib 11 (see figure 3), two support shelves 12 of a set of stiffeners 13, 14 (see figure 2) scarves 15, fastened together in accordance with figure 1, 2 and 3 by welding. The vertical plane of symmetry of the frame coincides with the axis of the high-pressure housing. On the supporting shelves of the frame in two parallel rows of 2 ... 10 pieces each, and optimally - 4 ... 6 pieces, catalyst baskets are installed, fixed with nuts 16. The baskets can be fixed to the power support frame and using brackets. The longitudinal axis of the baskets is vertical. MTU is fixed on the frame using brackets 17 and 18.

Each catalyst basket 6 consists of (see FIG. 3) a housing 19, a cover 20, a grate (shelf) 21, a gas distribution grid 22. To the lid and the housing of the basket, coaxially connected with the corresponding holes, nozzles for supplying 23 and gas outlet 24 are welded. Catalyst 25 is poured onto the grate grate in the form of granules, tablets, and grains. To reduce heat fluxes from the catalysis zone to the walls of the high-pressure housing, thermal insulation 26 is applied to the basket body. Gas ducts are connected to the nozzles 23 and 24 through flange connectors. The tightness of their joints, as well as the joint of the lid and the basket body, is ensured by means of seals.

MTU consists (see figure 4) of two flanges 27, the outer shell 28, the inner shell 29, the liner 30. The inner shell is inserted into the outer and hermetically fastened, as well as the outer, with flanges by welding. The insert is inserted into the inner shell and sandwiched between the MTU flange and the gas duct flange 9. The gaps between the shells and between the liner and the inner shell are from 0.5 to 5.0 mm. Radial holes are made in the flanges 27, coaxially with which the coolant supply and exhaust pipelines are welded to them. The gap between the outer and inner shells can be maintained with the help of noodles, wire, fins (direct or spiral), etc. The liner 30 acts as a filler and a gas flow turbulator. It forms a zone of intense heat transfer.

Through-hole 1 is provided with through holes, coaxially welded to it with fittings, pipelines, nozzles for supplying and removing coolant to each MTU, supplying synthesis gas, removing synthesis products, removing purging synthesis gas, outputs of various cables and pipelines from sensors control systems, etc. A gas duct for supplying purge synthesis gas 31 is also welded to the plate 1. The power plate is mounted vertically on a horizontal foundation and is fixedly attached to it. Between the housing and the elements of the catalyst block provide a mounting gap of at least 50 mm.

In the process of operation of the reactor, synthesis gas through the pipe mounted on the power plate 1, and through one of the gas ducts 8 enters the inlet of the first catalyst basket. Then, through the pipe 23 and the gas distribution grid 22, the synthesis gas passes into the catalytic bed 25, in the volume of which the catalytic synthesis takes place. In the catalyst basket, the gas is heated at 30 ... 60 ° C. To remove heat and cool the reaction gases through the gas duct 9, they are sent to the input of the MTU.

The flow diagram of the reaction gases and the coolant in the MTU is presented in figure 4. The coolant (water) through the radial holes in the flange 27 enters the distributing manifold 32, then passes in the gap between the outer and inner shell, enters the collection manifold 33, then it is discharged from the MTU through the radial hole in the lower flange and then from the reactor.

The reaction gases pass in the gap between the liner 30 and the inner wall, giving off heat to the coolant. The reaction gases sequentially pass through all baskets, cooling after each (except the last) in MTU and from the outlet of the last basket, through the second gas duct 8, as well as the pipe on the power plate 1, are removed from the reactor. To cool the high-pressure housing and the elements of the power support frame, as well as to unload the baskets from a large pressure drop, purge synthesis gas is used. It represents part or all of the consumption of synthesis gas, pre-cooled outside the reactor to 50 ... 100 ° C. The purge synthesis gas enters through the gas duct 31 into the space between the shelf nozzle, the high pressure housing, the reactor lid and the power plate, through the opening in which it is then removed from the reactor. It is recommended that the pressure of the syngas purge at the inlet to the reactor be always maintained greater than the syngas pressure at the inlet to the last basket, but not more than 1.0 MPa. Catalyst baskets are calculated for the same external overpressure.

The design of the reactor allows to simplify the assembly and disassembly of the device, for example, when replacing baskets, their rearrangement, when replacing the catalyst in baskets. In this case, the high-pressure housing is undocked from the power plate and, together with the reactor cover on the bogies, rolls along the axis to the side (see Fig. 5). To remove any basket, it is enough to undock the two gas ducts 9 and unscrew the nut 16. A crane, a forklift truck, and a hoist can provide maintenance for the catalyst block.

The efficiency of MTU is achieved by using the liner 30, which allows to increase the heat transfer coefficient from the reaction gases to the wall of the inner shell. In the gap between the liner and the shell 29, it is possible to provide the necessary flow rate of the reaction gases and to perform macro roughness elements that turbulent the flow. Such elements may be helical or annular protrusions, longitudinal ribs, "needles", etc. MTU is part of the gas pipeline connecting the outlet of the previous (along the gas) and the subsequent basket. The proposed technical solution allows to simplify the design of MTU and catalyst basket, to dismantle any basket and liner without dismantling the MTU and its strapping. Dismantling the liner may be necessary when refining the reactor to adjust the MTU parameters. Correction can be made by changing the length of the liner or macro-roughness on it. To ensure the reliability of the operation of the pressure reactor in the MTU (water) coolant circuits, it is recommended to keep the synthesis gas pressure below all operating modes, and MTU strapping using one-piece connections (welding or soldering).

During operation, as the catalyst is developed, it may be necessary to control the intensity of heat transfer in the MTU, i.e. the degree of cooling of the reaction gases. Such regulation is most easily done by changing the flow rate of the coolant. High values of the coefficient of heat transfer from the reaction gases to the wall provided by the design of the MTU, their commensurability with the values of the coefficient of heat transfer from the wall to the coolant allow you to expand the control range of the device.

The cylindrical shape of the baskets, in contrast to the box-shaped ones of the prototype, can significantly simplify the technology of their manufacture, as well as reduce their weight, taking into account the availability during external pressure.

The stresses arising at the site of termination of the support frame are inversely proportional to the square of the height of the power rib, and the mass of the frame is directly proportional to the height of the rib. In the proposed reactor, the rib of the support frame is located in the most convenient place, in terms of strength and rigidity, along the axis of the high-pressure housing. This circumstance makes it possible, ceteris paribus, to reduce the mass of the structure by performing a power rib of maximum height, to simplify the technology of its manufacture. The rib can be made of a thin sheet or several sheets welded in the form of a box. It can have perforation and a variable height along the length of the support frame to reduce weight.

To compensate for the overturning moment and reduce the loads on the foundation and the power plate, the use of a twin reactor is possible. In this case, the power plates of the reactors are lightweight and install them, as shown in Fig.6, connecting the upper parts with ties.

Claims (2)

1. A horizontal multi-shelf catalytic reactor for heat-intense processes of the chemical synthesis of hydrocarbons, alcohols, ethers, containing a vertical power plate mounted on a horizontal foundation, a cylindrical high-pressure housing with a cover detachable and hermetically sealed with it, the longitudinal axis of which is horizontal and along which the housing has the ability move on carts along the foundation site, as well as the catalyst block, consisting of a set of catalyst baskets, a power support frame, n which install baskets of modular heat exchangers that provide cooling of the reaction gases by an external heat carrier and located in volumes between the catalyst baskets, onto which the solid catalyst is placed on the grate racks-shelves, strapping elements, characterized in that each catalyst basket has a cylinder shape, the longitudinal axis of which is vertical, all baskets are tight and designed for external overpressure up to 1.0 MPa, while the baskets are installed in two parallel rows of 2-10 sh the knock in each and is fixed on the power support frame, which is a cross-section beam, consisting of a longitudinal power rib and two support shelves, cantilevered on the power plate, while the vertical plane of symmetry of the frame coincides with the longitudinal axis of the high-pressure housing and between the catalyst baskets and a cylindrical body provide an installation clearance of at least 50 mm, and all inlets and outlets are made through a vertical power plate. 2. The reactor according to claim 1, characterized in that each modular heat exchanger device consists of two cylindrical shells coaxially inserted into each other with a gap of 0.5 to 5 mm for the passage of coolant, and an insert with a gap for passage is installed in the inner shell reaction gases from 0.5 to 5.0 mm, on the lateral surface of which there are elements of macro-roughness, while each modular heat exchanger is mounted on a power support frame and is connected by gas ducts along the path of the reaction gases to the outlet of the previous gas in and the entrance of the subsequent baskets, being part of the pipeline connecting them.

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