Radial flow fixed bed catalytic reactor for co carbonylation coupling to oxalate

Abstract

The application discloses a radial flow fixed bed catalytic reactor for CO carbonylation coupling to generate oxalate, which comprises a cylindrical container composed of an upper head, a cylindrical barrel and a lower head from top to bottom in sequence, and the cylindrical container is externally provided with a reaction gas feeding port, a reaction gas discharging port, a heat exchange medium inlet, a heat exchange medium outlet, a catalyst feeding port and a catalyst discharging port; a catalytic bed is divided into an adiabatic zone and a heat exchange zone from inside to outside, and the heat exchange zone is provided with multiple groups of concentric circular arranged heat exchange pipes which are arranged in two rows as a group. The radial flow fixed bed catalytic reactor for CO carbonylation coupling to generate oxalate has the characteristics of uniform axial distribution of reaction gas, reasonable bed temperature distribution, high catalyst utilization rate and small reactor pressure drop, and is suitable for the reaction of carbonylation coupling to generate ester and is also suitable for other exothermic gas-solid phase catalytic reactions.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical reaction engineering, and in particular relates to a reactor for exothermic catalytic reaction, and more particularly to a radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate. Background Art

[0002] Ethylene glycol is a key raw material for polyester synthesis. The ethylene glycol industry primarily operates through the ethylene route and coal-based syngas. The coal-based syngas route, which aligns with my country's resource development strategy, has experienced particularly rapid growth. Most coal-based syngas routes currently in production utilize the oxalate process. In the first step, nitrite reacts with carbon monoxide to form oxalate and nitric oxide. In the second step, the oxalate is partially hydrogenated to produce ethylene glycol.

[0003] The reaction temperature of CO carbonylation coupling to produce dimethyl oxalate is 110-140°C, and the reaction pressure is 0.1-0.5 MPa. The reaction is an irreversible exothermic reaction with a large amount of heat release and a small reaction temperature range, so the heat exchange efficiency of the reactor is required to be high.

[0004] Currently, a fixed-bed catalytic reactor is generally used for the catalytic reaction process of synthesizing dimethyl oxalate, and more specifically, an axial shell-and-tube reactor or a radial reactor.

[0005] Shell-and-tube reactors offer continuous heat exchange within their beds, resulting in uniform reaction temperatures and high conversion rates. However, the catalysts used in carbonylation reactions have poor thermal conductivity, limiting the diameter of the tubes. Currently, the tubes of carbonylation reactors are mostly Φ25×2 to Φ32×2, resulting in low reactor volume utilization. Due to equipment processing limitations, the reactor diameter cannot be too large, resulting in a very high reactor bed height, large bed resistance, and high energy consumption. Furthermore, with the emergence of a single-series large-scale trend in chemical production equipment, large-diameter reactors present currently insurmountable difficulties in processing, manufacturing, and transportation, limiting the industrial application of large-scale shell-and-tube reactors.

[0006] A radial flow fixed-bed catalytic reactor is used to reduce reactor bed resistance, increase space velocity, and boost production capacity. Compared to exothermic gas-solid phase catalytic reactions like methanol synthesis, the catalyst for the carbonylation reaction of dimethyl oxalate synthesis is more temperature-sensitive, requiring timely removal of reaction heat to lower the reaction temperature. Multi-stage adiabatic reactors, which utilize inter-stage heat exchange and are widely used in industrial reactors, are unable to maintain adequate temperature control.

[0007] To improve reaction efficiency, reduce pressure drop losses within the reactor, maximize high-temperature heat recovery, fully extend the service life of the catalyst, and better meet the needs of large-scale reactors, many engineers and technicians have developed radial fixed-bed catalytic reactors with heat exchange within the bed. U.S. Patent No. 4,321,234 discloses a radial flow fixed-bed catalytic reactor. This reactor provides a fluid flow pattern and heat exchange tube arrangement, overcoming the disadvantage of high bed resistance in shell-and-tube fixed-bed reactors while effectively utilizing reaction heat. However, the reactor suffers from severe fluid unevenness, and the heat exchange tubes are arranged row by row, which prevents the catalyst from being fully utilized during the catalytic reaction of dimethyl oxalate synthesis.

[0008] Patent application publication number CN206500146U discloses a water-circulated natural circulation coiled-tube reactor suitable for synthesizing dimethyl oxalate. While its heat exchange efficiency is improved, its structure is complex, making it difficult to scale up. Patent application publication number CN109395667A discloses a coiled-tube isothermal radial reactor suitable for synthesizing dimethyl oxalate. This reactor achieves temperature control through a large number of coiled tubes, but the reactor has numerous internal components, a complex gas flow pattern, and poor gas distribution within the reactor.

[0009] Patent applications with publication numbers CN102872767A and CN104841340A disclose two radial flow isothermal fixed-bed catalytic reactors suitable for the synthesis of dimethyl oxalate. They use a plate heat exchanger with an integrated heat exchange unit design, but the structure is complex, maintenance is difficult, and catalyst loading and unloading is inconvenient. The plate heat exchanger has a risk of leakage. At the same time, the plate structure causes uneven thickness of the catalyst, which is prone to local overheating. Local overheating can easily cause thermal decomposition of methyl nitrite in this reaction, posing a risk of explosion.

[0010] The existing reactor structure, heat exchange method and reaction gas flow method have the following problems:

[0011] 1. The radial reactor with centripetal flow has a gradually increasing fluid flow velocity along the radial direction, a low inlet linear velocity, a rapid temperature rise, a short insulation layer, and is difficult to process. At the same time, for chemical reactions that are severely constrained by equilibrium, the reaction velocity inside the bed slows down significantly, while the linear velocity is high. The mismatch between the two will affect the efficiency of the radial reactor.

[0012] 2. The radial reactor adopts a centripetal flow from outside to inside. The reaction gas flows in the diversion channel between the cylinder and the outer distribution cylinder. Due to the temperature difference caused by heat loss, a considerable temperature difference will be generated in the axial direction of the bed.

[0013] 3. The heat exchange components in the reactor are difficult to meet the heat exchange requirements; the plate heat exchange unit has a complex structure, high processing difficulty, leakage risk, uneven catalyst thickness, and is prone to danger; the coil and coil heat exchange unit has a complex structure, and the catalyst loading and unloading is difficult, and the problem of uneven heat exchange cannot be completely avoided.

[0014] 4. For the row-by-row arrangement of heat exchange tubes, the temperature distribution behind each row of heat exchange tubes is wavy, with the hot spot in the radial direction between the two heat exchange tubes. The rear row of heat exchange tubes is also arranged at the hot spot. However, due to the particularity of the radial bed, the center distance of each row of heat exchange tubes varies greatly with the radial position. For the arrangement of heat exchange tubes with the same number of tubes, the tubes are sparsely arranged on the outside of the bed, while the tubes are densely arranged on the inside of the bed, which cannot meet the overall heat exchange requirements. Hot spots or low-temperature areas are prone to occur, affecting the overall efficiency of the catalytic reaction. Summary of the Invention

[0015] The present invention aims to provide a radial flow fixed-bed catalytic reactor for the carbonylation coupling of CO to produce oxalate. The reactor is a centrifugal flow radial reactor with a special arrangement of heat exchange tubes. This reactor achieves uniform distribution of bed fluid while improving heat exchange efficiency and alleviating the problem of uneven bed temperature distribution. At the same time, the reactor has a relatively simple structure and is suitable for large-scale processing, manufacturing, and transportation of the reaction device.

[0016] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0017] The concept of the present invention is as follows:

[0018] The present invention adopts a low-pressure-drop centrifugal radial reactor. The reaction gas flows from the inside to the outside in the catalytic bed, which satisfies the matching between the reaction gas flow rate and the reaction rate, fully exerts the catalytic reaction efficiency of the radial reactor, and fundamentally and completely eliminates the occurrence of large temperature differences in the axial direction of the bed due to heat loss.

[0019] The present invention divides the catalytic bed from the inside out into an adiabatic zone and a heat exchange zone. The adiabatic zone ensures the initial reaction temperature rise, while heat exchange tubes are installed in the heat exchange zone to remove reaction heat and prevent the catalytic bed from overheating. The heat exchange zone is equipped with multiple rows of heat exchange tubes arranged concentrically with the radial reactor. Each row of heat exchange tubes is a group of two, with the same number of tubes and staggered. This effectively reduces the amplitude of temperature fluctuations behind the heat exchange tubes, improves the temperature uniformity of the catalytic bed, and fully utilizes the overall performance of the catalytic bed. Each group of heat exchange tubes is arranged in groups in the catalytic bed, and the appropriate number of groups is set according to the depth of the heat exchange zone.

[0020] The present invention adopts a ∏-shaped radial reactor form, so that the gas makes a counter-directional relative flow in the diverter flow channel and the collecting flow channel, and adopts appropriate diverter flow channel and collecting flow channel cross-section control technology, so that the difference in static pressure difference between the two flow channels can be eliminated along the axial direction, and the distributor adopts a high-porosity distribution cylinder with uniform openings, which can ensure the uniform distribution of gas without controlling the pressure drop; or adopts a Z-shaped radial reactor form, so that the gas makes a unidirectional relative flow in the diverter flow channel and the collecting flow channel, and adopts appropriate guide cone distribution control technology, so that the difference in static pressure difference between the two flow channels can be eliminated along the axial direction, and the distributor adopts a high-porosity distribution cylinder with uniform openings, which can ensure the uniform distribution of gas without controlling the pressure drop.

[0021] The present invention uses straight heat exchange tubes with a simple structure and easy catalyst loading and unloading. The special arrangement avoids the problem of excessively high catalyst bed temperature between heat exchange tubes in the traditional arrangement while increasing the catalyst filling volume.

[0022] The present invention adopts a radial reactor form. Under the premise of ensuring a radial thin catalyst bed, the axial height of the bed is gradually increased as the scale increases, and the device is easy to be scaled up.

[0023] According to the above concept, the technical solution adopted by the present invention is as follows:

[0024] The present invention provides a radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate, comprising a cylindrical container consisting of an upper head, a cylindrical barrel, and a lower head in order from top to bottom, wherein the cylindrical container is provided with a reaction gas feed inlet, a reaction gas discharge inlet, a heat exchange medium inlet, a heat exchange medium outlet, a catalyst feed inlet, and a catalyst discharge inlet on the outside;

[0025] The interior of the cylindrical container is provided with: a porous-walled cylindrical inner distribution tube and a porous-walled cylindrical outer distribution tube, which are coaxially arranged with the cylindrical body and arranged in sequence from the inside to the outside; a catalyst is filled between the inner distribution tube and the outer distribution tube to form a catalytic bed, and a catalyst seal is provided above the catalytic bed; the catalytic bed is divided into an insulating zone and a heat exchange zone from the inside to the outside, and the heat exchange zone is provided with multiple rows of concentrically arranged heat exchange tubes coaxially with the cylindrical body; the heat exchange tubes are connected to the heat exchange medium inlet through a diverter ring tube at the bottom and to the heat exchange medium outlet through a collecting ring tube at the top; the catalyst feed port and the heat exchange medium outlet are located on both sides of the upper head, and the catalyst discharge port and the heat exchange medium inlet are located on both sides of the lower head;

[0026] There are two types of reactors:

[0027] (a) the reaction gas inlet is arranged on the upper head and connected to the porous-wall cylindrical inner distribution cylinder through an expansion joint, the inner space of the porous-wall cylindrical inner distribution cylinder constitutes a shunt flow channel for the reaction gas; the upper part of the porous-wall cylindrical outer distribution cylinder is connected to the upper part of the cylindrical cylinder through an annular sealing plate, and the annular space between the porous-wall cylindrical outer distribution cylinder and the sidewall of the cylindrical cylinder constitutes a collecting flow channel connected to the reaction gas outlet; the reaction gas outlet is located on the outside of the cylindrical cylinder and on the same side as the catalyst inlet; the reactor is a π-shaped radial reactor; the reaction gas enters from the upper part of the reactor, flows downward in the shunt flow channel, enters the adiabatic zone and the heat exchange zone of the catalyst bed in sequence after passing through the porous-wall cylindrical inner distribution cylinder, enters the collecting flow channel through the porous-wall cylindrical outer distribution cylinder, flows upward in the collecting flow channel, and finally leaves the reactor through the reaction gas outlet;

[0028] (b) the reaction gas inlet is arranged on the lower head and connected to the porous-wall cylindrical inner distribution cylinder, the porous-wall cylindrical inner distribution cylinder is provided with an inverted conical flow guide, and the annular space between the porous-wall cylindrical inner distribution cylinder and the conical flow guide constitutes a shunt flow channel for the reaction gas; the annular space between the porous-wall cylindrical inner distribution cylinder and the sidewall of the cylindrical cylinder constitutes a collecting flow channel connected to the reaction gas outlet arranged on the upper head; the reactor is a Z-shaped radial reactor; the reaction gas enters from the lower part of the reactor, flows upward in the shunt flow channel, enters the adiabatic zone and the heat exchange zone of the catalyst bed in sequence after passing through the porous-wall cylindrical inner distribution cylinder, enters the collecting flow channel through the porous-wall cylindrical outer distribution cylinder, flows upward in the collecting flow channel, and finally leaves the reactor through the reaction gas outlet;

[0029] The heat exchange pipes are arranged in groups of two rows, and the two rows of heat exchange pipes have the same number of pipes and are arranged in an interval-crossing manner.

[0030] The heat exchange medium enters the reactor through the heat exchange medium inlet of the lower head, enters the heat exchange pipes through the shunt ring pipe, exchanges heat in the catalyst bed, and then flows out of the reactor through the collecting ring pipe and the heat exchange medium outlet located on the upper head.

[0031] The thickness of the adiabatic zone is 50mm-300mm.

[0032] The diameter of the heat exchange pipe is 20mm-100mm, the center distance of each row of heat exchange pipes is 1.2-2.5 times the diameter of the heat exchange pipe, the center distance of the two rows of heat exchange pipes in the same group is 1.2-3.5 times the diameter of the heat exchange pipe, and the difference between the arrangement radius of the inner row of heat exchange pipes in the rear group and the arrangement radius of the outer row of heat exchange pipes in the front group is 2.5-10 times the diameter of the heat exchange pipe.

[0033] The heat exchange pipes are arranged in groups of two rows, and 2-6 groups are arranged in the radial direction of the heat exchange zone.

[0034] The baffles on both sides of the catalyst seal have no holes; the height of the catalyst seal is 1.2 to 2 times the thickness of the catalyst bed.

[0035] The inner distribution tube and the outer distribution tube are provided with small holes at corresponding parts of the catalytic bed layer, and the opening heights of the inner distribution tube and the outer distribution tube are consistent with the height of the upper end of the catalytic bed layer.

[0036] The effective height of the heat exchange tube is consistent with the catalyst filling height.

[0037] The ratio of the cross-sectional area of ​​the diverter channel to the cross-sectional area of ​​the collector channel is 0.5 to 1.0.

[0038] Due to the adoption of the above technical solution, the present invention has the following advantages and beneficial effects:

[0039] The radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate is a centrifugal flow radial reactor with a special arrangement of heat exchange tubes. This reactor achieves uniform distribution of bed fluid while improving heat exchange efficiency and alleviating the problem of uneven bed temperature distribution. The reactor has a relatively simple structure and is suitable for large-scale processing, manufacturing, and transportation of reaction devices.

[0040] The radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate has the characteristics of uniform distribution of reaction gas along the axial direction, reasonable bed temperature distribution, high catalyst utilization rate, and low reactor pressure drop. It is suitable for carbonylation coupling reactions to produce esters and is also suitable for other exothermic gas-solid phase catalytic reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the π-type structure in a radial flow fixed-bed catalytic reactor for CO carbonylation coupling to produce oxalate.

[0042] Figure 2 Schematic diagram of the Z-type structure in a radial flow fixed-bed catalytic reactor for the carbonylation coupling of CO to produce oxalate.

[0043] Figure 3 This is a schematic cross-sectional view of the arrangement of heat exchange tubes in a radial flow fixed-bed catalytic reactor for the carbonylation coupling of CO to produce oxalate.

[0044] Figure 4 Schematic diagram of the heat exchange tubes set as single-row tubes.

[0045] Figure 5 This is a schematic diagram of the heat exchange tubes being arranged as double rows of tubes, with the same number of tubes in both rows.

[0046] Figure 6This is a schematic diagram of a double-row heat exchange tube configuration with different numbers of tubes in the two rows.

[0047] Figure 7 It is a schematic diagram comparing the radial bed temperature changes after single-row tubes and double-row tubes (the number of tubes in both rows is the same).

[0048] Figure 8 This is a schematic diagram comparing the radial bed temperature changes behind double-row tubes with the same and different numbers of tubes.

[0049] Among them, 1 is the feed port; 2 is the heat exchange medium outlet; 3 is the upper head; 4 is the collecting ring pipe; 5 is the heat exchange tube; 6 is the collecting flow channel; 7 is the diversion flow channel; 8 is the external distribution tube; 9 is the diversion ring pipe; 10 is the heat exchange medium inlet; 11 is the catalyst unloading port; 12 is the lower head; 13 is the internal distribution tube; 14 is the catalyst bed; 15 is the cylindrical cylinder; 16 is the discharge port; 17 is the catalyst seal; 18 is the annular sealing plate; 19 is the catalyst feed port; 20 is the expansion joint; 21 is the conical guide body; 22 is the insulation area; 23 is the heat exchange area. DETAILED DESCRIPTION

[0050] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0051] A radial flow fixed-bed catalytic reactor for carbonylation coupling of carbon monoxide to produce oxalate esters utilizes a circular pressure vessel with a catalytic bed 14. A reactant gas feed port 1 is connected to an inner distribution tube 13, forming a splitter flow channel 7 for the reactant gas. The space between a cylindrical body 15 and an outer distribution tube 8 forms a collector flow channel 6 for the reactant gas, which is connected to a discharge port 16. The space between the outer distribution tube 8 and the inner distribution tube 13 forms the catalytic bed 14. The catalytic bed 14 is divided from the inside out into an adiabatic zone 22 and a heat exchange zone 23. Heat exchange tubes 5 are arranged in two concentric rows within the heat exchange zone 23. The reactant gas flows radially through the catalytic bed 14 in a centrifugal manner. The heat exchange medium enters the reactor through a heat exchange medium inlet 10 in the lower head 12, passes through a splitter loop 9, and enters the heat exchange tubes 5. After heat exchange within the catalytic bed 14, the heat exchange medium flows through a collector loop 4 and out of the reactor through a heat exchange medium outlet 2 located in the upper head 3.

[0052] There are two specific forms:

[0053] like Figure 1 As shown, Figure 1 Schematic diagram of a π-type structure in a radial flow fixed bed catalytic reactor for carbonylation coupling of CO to produce oxalate. The centrifugal π-type flow fixed bed intra-bed heat exchange radial catalytic reactor of the present invention comprises:

[0054] A radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate comprises a cylindrical container consisting, from top to bottom, of an upper end cap 3, a cylindrical barrel 15, and a lower end cap 12. The cylindrical container is provided with a reaction gas feed port 1, a reaction gas discharge port 16, a heat exchange medium inlet 10, a heat exchange medium outlet 2, a catalyst feed port 19, and a catalyst discharge port 11 on the outside.

[0055] The cylindrical container is provided with: a porous wall cylindrical inner distribution tube 13 and a porous wall cylindrical outer distribution tube 8 arranged coaxially with the cylindrical barrel 15 and arranged in sequence from the inside to the outside; a catalyst is filled between the inner distribution tube 13 and the outer distribution tube 8 to form a catalyst bed 14, and the arrangement of the heat exchange tubes 5 in the catalyst bed 14 is as follows Figure 3 As shown, Figure 3 This is a schematic cross-sectional view of the arrangement of heat exchange tubes in a radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to oxalate. A catalyst seal 17 is located above the catalytic bed 14. The catalytic bed 14 is divided from the inside out into an insulation zone 22 and a heat exchange zone 23. The heat exchange zone 23 is provided with multiple rows of concentrically arranged heat exchange tubes 5 coaxially disposed with the cylindrical body 15. The heat exchange tubes 5 are connected to the heat exchange medium inlet 10 at the bottom via a diverter ring 9 and to the heat exchange medium outlet 2 at the top via a collecting ring 4. The catalyst feed port 19 and the heat exchange medium outlet 2 are located on either side of the upper head 3, while the catalyst discharge port 11 and the heat exchange medium inlet 10 are located on either side of the lower head 12.

[0056] The area where the catalytic bed 14 is close to the inner distribution tube 13 is the insulation zone 22. The temperature in the insulation zone 22 should not exceed the maximum temperature allowed by the reaction.

[0057] (a) The reaction gas feed port 1 is provided on the upper head 3 and is connected to the porous wall cylindrical inner distribution tube 13 through the expansion joint 20. The internal space of the porous wall cylindrical inner distribution tube 13 constitutes a diversion flow channel 7 for the reaction gas; the upper portion of the porous wall cylindrical outer distribution tube 8 is connected to the upper portion of the cylindrical barrel 15 through an annular sealing plate 18, and the annular gap space between the porous wall cylindrical outer distribution tube 8 and the side wall of the cylindrical barrel 15 constitutes a collecting flow channel 6, which is connected to the reaction gas discharge port 16; the reaction gas discharge port 16 is located on the outer side of the cylindrical barrel 15, on the same side as the catalyst feed port 19; the reactor is a ∏-type radial reactor;

[0058] Reaction gas enters from the upper part of the reactor, flows from top to bottom in the flow distribution channel 7, enters the adiabatic zone 22 and the heat exchange zone 23 of the catalytic bed 14 in turn after passing through the porous wall cylindrical inner distribution cylinder 13, the reaction gas is reacted in the adiabatic zone 22, the temperature of the reaction gas is raised, and then enters the heat exchange zone 23, removes heat through the multiple sets of heat exchange pipes 5, ensures the normal progress of the reaction, the reaction gas flows centrifugally from inside to outside in the catalytic bed 14, enters the flow collection channel 6 through the porous wall cylindrical outer distribution cylinder 8, flows from bottom to top in the flow collection channel 6, and finally leaves the reactor through the reaction gas discharge port 16;

[0059] The heat exchange pipes 5 are arranged in groups of two rows, the two rows of heat exchange pipes have the same number of pipes, and are arranged in an interval staggered manner.

[0060] The heat exchange medium enters the reactor through the heat exchange medium inlet 10 of the lower head 12, enters the heat exchange pipes 5 through the flow distribution ring 9, exchanges heat in the catalytic bed 14, and then flows out of the reactor through the heat exchange medium outlet 2 located in the upper head 3 through the flow collection ring 4.

[0061] The thickness of the adiabatic zone 22 is 50mm-300mm.

[0062] The diameter of the heat exchange pipes 5 is 20mm-100mm, the center distance of each row of heat exchange pipes is 1.2-2.5 times the diameter of the heat exchange pipes, the center distance of the two rows of heat exchange pipes in the same group is 1.2-3.5 times the diameter of the heat exchange pipes, and the difference between the arrangement radius of the inner row of heat exchange pipes in the rear group and the arrangement radius of the outer row of heat exchange pipes in the front group is 2.5-10 times the diameter of the heat exchange pipes. Two rows of heat exchange pipes 5 are arranged in a group, each group is arranged in the heat exchange zone 23, the temperature in the heat exchange zone 23 should not exceed the maximum allowable temperature of the reaction, and the appropriate number of groups is arranged in the radial direction of the heat exchange zone 23 according to the thickness of the catalytic bed 14.

[0063] The heat exchange pipes 5 are arranged in groups of two rows, and 2-6 groups are arranged in the radial direction of the heat exchange zone 23.

[0064] The two side baffles of the catalyst seal 17 are not perforated, and the height of the catalyst seal 17 is 1.2-2 times the thickness of the catalytic bed 14.

[0065] The inner distribution cylinder 13 and the outer distribution cylinder 8 are provided with small holes in the corresponding part of the catalytic bed 14, and the opening height of the inner distribution cylinder 13 and the opening height of the outer distribution cylinder 8 are consistent with the height of the upper end of the catalytic bed 14.

[0066] The inner distribution cylinder 13 and the outer distribution cylinder 8 are arranged on the lower head 12 to form a ring-shaped catalytic bed 14 filled with catalyst.

[0067] The effective height of the heat exchange pipes 5 is consistent with the height of the catalyst filling.

[0068] The ratio of the cross-sectional area of the shunt flow channel 7 to the cross-sectional area of the collecting flow channel 6 is 0.5-1.0.

[0069] The top of the collecting flow channel 6 is separated from the space inside the upper head 3 by an annular sealing plate 18.

[0070] As shown in Figure 2 , Figure 2 is a schematic diagram of a Z-shaped structure in a radial flow fixed-bed catalytic reactor for the carbonylation coupling of CO to generate oxalate. Figure 2 As shown is a centrifugal Z-shaped flow heat exchange radial catalytic reactor.

[0071] A radial flow fixed-bed catalytic reactor for the carbonylation coupling of CO to generate oxalate, comprising a cylindrical container composed of an upper head 3, a cylindrical barrel 15, and a lower head 12 from top to bottom, and provided on the outside of the cylindrical container with a reaction gas inlet 1, a reaction gas outlet 16, a heat exchange medium inlet 10, a heat exchange medium outlet 2, a catalyst inlet 19, and a catalyst outlet 11;

[0072] The inside of the cylindrical container is provided with: a perforated wall cylindrical inner distribution cylinder 13 and a perforated wall cylindrical outer distribution cylinder 8 arranged in sequence from inside to outside, coaxially arranged with the cylindrical barrel 15; the catalyst is filled between the inner distribution cylinder 13 and the outer distribution cylinder 8 to form a catalytic bed 14, and a catalyst seal 17 is provided above the catalytic bed 14; the catalytic bed 14 is divided into an adiabatic zone 22 and a heat exchange zone 23 from inside to outside, and the heat exchange zone 23 is provided with a plurality of rows of concentric circularly arranged heat exchange pipes 5 coaxially arranged with the cylindrical barrel 15; the heat exchange pipes 5 are connected at the bottom with the heat exchange medium inlet 10 through a shunt ring pipe 9, and at the top with the heat exchange medium outlet 2 through a collecting ring pipe 4; the catalyst inlet 19 and the heat exchange medium outlet 2 are located on both sides of the upper head 3, and the catalyst outlet 11 and the heat exchange medium inlet 10 are located on both sides of the lower head 12;

[0073] (b) the reaction gas inlet 1 is provided on the lower head 12 and communicates with the perforated wall cylindrical inner distribution cylinder 13, the perforated wall cylindrical inner distribution cylinder 13 is provided with an inverted conical flow guide 21, and the annular space between the perforated wall cylindrical inner distribution cylinder 13 and the conical flow guide 21 constitutes a reaction gas shunt flow channel 7; the annular space between the perforated wall cylindrical inner distribution cylinder 13 and the side wall of the cylindrical barrel 15 constitutes a collecting flow channel 6, which communicates with the reaction gas outlet 16 provided on the upper head 3; the reactor is a Z-shaped radial reactor;

[0074] The reaction gas enters the reactor from the reaction gas feed port 1 of the lower head 12, enters the branch flow channel 7 and flows from bottom to top, passes through the porous-walled cylindrical inner distribution tube 13, and then enters the adiabatic zone 22 and the heat exchange zone 23 of the catalytic bed 14 in sequence. The reaction first undergoes reaction in the adiabatic zone 22, and the temperature of the reaction gas rises. Then, it enters the heat exchange zone 23, and heat is removed by multiple groups of heat exchange tubes 5 to ensure the normal progress of the reaction. The reaction gas flows centrifugally from the inside to the outside in the catalytic bed 14, passes through the porous-walled cylindrical outer distribution tube 8 and enters the collecting flow channel 6. The reaction gas flows from bottom to top in the collecting flow channel 6, passes through the internal space of the upper head 3, and finally leaves the reactor through the reaction gas discharge port 16.

[0075] The heat exchange tubes 5 are grouped into two rows, with the number of heat exchange tubes in the two rows being the same and arranged crosswise at intervals;

[0076] The heat exchange medium enters the reactor through the heat exchange medium inlet 10 of the lower head 12, and enters the heat exchange tube 5 through the diversion loop 9. After heat exchange in the catalytic bed 14, it passes through the collecting loop 4 and flows out of the reactor through the heat exchange medium outlet 2 located at the upper head 3.

[0077] The thickness of the thermal insulation area 22 is 50 mm to 300 mm.

[0078] The diameter of the heat exchange tube 5 is 20mm-100mm, the center distance of each row of heat exchange tubes is 1.2 to 2.5 times the diameter of the heat exchange tube, the center distance of two rows of heat exchange tubes in the same group is 1.2 to 3.5 times the diameter of the heat exchange tube, and the difference between the arrangement radius of the inner row of heat exchange tubes in the rear group and the arrangement radius of the outer row of heat exchange tubes in the front group between different groups is 2.5 to 10 times the diameter of the heat exchange tube.

[0079] The heat exchange tubes 5 are grouped in pairs, and 2 to 6 groups are arranged in the radial direction of the heat exchange zone 23 .

[0080] The baffles on both sides of the catalyst seal 17 are not opened; the height of the catalyst seal 17 is 1.2 to 2 times the thickness of the catalyst bed 14.

[0081] The inner distribution tube 13 and the outer distribution tube 8 have small holes in the corresponding parts of the catalytic bed 14 , and the opening heights of the inner distribution tube 13 and the outer distribution tube 8 are consistent with the upper end height of the catalytic bed 14 .

[0082] The effective height of the heat exchange tube 5 is consistent with the catalyst filling height.

[0083] The ratio of the cross-sectional area of ​​the diverter channel 7 to the cross-sectional area of ​​the collector channel 6 is 0.5 to 1.0.

[0084] Example 1

[0085] 100,000 tons / year methyl nitrite carbonylation to dimethyl oxalate plant, the reactor uses Figure 1 The structure of the ∏-type fixed-bed radial reactor for methyl nitrite carbonylation is shown, and the feed gas is 11640Nm 3 / (m 3 h), the composition of the raw gas is: CO20%, CH3ONO 10%, NO 1%, N2 69%, the reaction feed temperature is 125°C, the heat exchange medium temperature is 118°C, the reaction temperature is less than 140°C, the pressure is 0.3 MPa, the reactor diameter is 4000mm, the axial height of the catalyst bed is 6000mm, the radial thickness of the bed is 700mm, of which the thickness of the insulation zone is 160mm and the thickness of the heat exchange zone is 540mm. The heat exchange tubes in the bed are arranged as follows Figure 3 As shown, there are three groups and six rows. The first group has 108 heat exchange tubes in the first row, with a core radius of 1.06 m, and the second row has 108 heat exchange tubes in the second row, with a core radius of 1.11 m. The second group has 132 heat exchange tubes in the first row, with a core radius of 1.235 m, and the second row has 132 heat exchange tubes in the second row, with a core radius of 1.285 m. The third group has 148 heat exchange tubes in the first row, with a core radius of 1.415 m, and the second row has 148 heat exchange tubes in the third row, with a core radius of 1.465 m. A total of 776 heat exchange tubes with an outer diameter of 38 mm are used. The bed is filled with 5x5 mm cylindrical Pd / α-Al2O3 catalyst. The reactor has a pressure drop of 11 kPa, a space-time yield of dimethyl oxalate of 0.608 g / (g cat·h), and a production capacity of 107,800 tons / year (based on 8,000 hours).

[0086] Example 2

[0087] 100,000 tons / year methyl nitrite carbonylation to dimethyl oxalate plant, the reactor uses Figure 2 The Z-type methyl nitrite carbonylation fixed bed radial reactor structure is shown, with a feed gas of 11640 Nm 3 / (m 3 h), the composition of the raw gas is: CO20%, CH3ONO 10%, NO 1%, N2 69%, the reaction feed temperature is 125°C, the heat exchange medium temperature is 118°C, the reaction temperature is less than 140°C, the pressure is 0.3 MPa, the reactor diameter is 4000mm, the axial height of the catalyst bed is 6000mm, the radial thickness of the bed is 700mm, of which the thickness of the insulation zone is 160mm and the thickness of the heat exchange zone is 540mm. The heat exchange tubes in the bed are arranged as follows Figure 3As shown, there are three groups and six rows. The first group has 108 heat exchange tubes in the first row, with a core radius of 1.06 m, and the second row has 108 heat exchange tubes in the second row, with a core radius of 1.11 m. The second group has 132 heat exchange tubes in the first row, with a core radius of 1.235 m, and the second row has 132 heat exchange tubes in the second row, with a core radius of 1.285 m. The third group has 148 heat exchange tubes in the first row, with a core radius of 1.415 m, and the second row has 148 heat exchange tubes in the third row, with a core radius of 1.465 m. A total of 776 heat exchange tubes with an outer diameter of 38 mm are used. The bed is filled with 5x5 mm cylindrical Pd / α-Al2O3 catalyst. The reactor has a pressure drop of 11 kPa, a space-time yield of dimethyl oxalate of 0.608 g / (g cat·h), and a production capacity of 107,800 tons / year (based on 8,000 hours).

[0088] In the present invention, every two rows of heat exchange tubes 5 form a group, the two rows of heat exchange tubes have the same number of tubes, and are arranged crosswise at intervals. Figure 4 This is a schematic diagram of the heat exchange tube being set as a single row of tubes. Figure 5 This is a schematic diagram of a double-row heat exchange tube configuration with the same number of tubes in both rows. Figure 6 This is a schematic diagram of a double-row heat exchange tube configuration with different numbers of tubes in the two rows. Figure 4 、 Figure 5 and Figure 6 In the 1 / 4 model, the arrangement mode and characteristic position of the heat exchange tube 5 are selected. The reactants pass through the catalytic bed 14 from the inside to the outside along the radial direction. The inner radius of the catalytic bed 14 is 0.3m, and the outer radius is 0.65m. The core radius of the first row of heat exchange tubes is 0.47m, and 12 heat exchange tubes with an outer diameter of 38mm are arranged; the core radius of the second row of heat exchange tubes is 0.52m. Figure 5 There are 12 heat exchange tubes with an outer diameter of 38mm arranged in the middle. Figure 6 13 heat exchange tubes with an outer diameter of 38mm are arranged in the middle; the radial position R = 0.57m (dashed line in the figure) is taken as the characteristic position. The schematic diagram of the comparison of the radial bed temperature changes after single-row tubes and double-row tubes is shown in the figure. Figure 7 As shown in the figure, the temperature at the characteristic position of the two is compared with the angle change. Figure 7 It can be seen from the figure that the temperature fluctuation is large and the distribution is very uneven when the single-row tube arrangement is used. When the double-row tube arrangement is used, the two rows of heat exchange tubes correspond to each other, and the high-temperature area in the front row is transferred to the heat exchange tubes in the rear row, making the temperature fluctuation small and the distribution more uniform. The schematic diagram of the radial bed temperature change after the double-row tube arrangement with the same and different numbers of tubes is shown in the figure. Figure 8 As shown in the figure, the temperature at the characteristic position of the two is compared with the angle change. Figure 8 It can be seen that compared with the double-row arrangement with the same number of heat exchange tubes, the two rows of heat exchange tubes in the double-row arrangement with different numbers of heat exchange tubes cannot correspond front to back, resulting in overlapping high-temperature leakage and low-temperature heat exchange, and uneven bed temperature distribution.

[0089] The radial flow fixed bed catalytic reactor for CO carbonylation coupling to generate oxalate has the following advantages:

[0090] 1. The centrifugal radial reactor is used, the reaction gas flows from inside to outside in the catalytic bed, the matching of the reaction gas flow rate and the reaction rate is met, the catalytic reaction efficiency of the radial reactor is fully played, and the axial temperature difference of the bed caused by heat loss is fundamentally completely eliminated.

[0091] 2. The heat exchange pipes in the heat exchange zone are arranged in an interval staggered manner every two rows, the temperature fluctuation range behind the heat exchange pipes is effectively reduced, the uniformity of the catalytic bed temperature is improved, and the overall performance of the catalytic bed is fully played.

[0092] 3. The cross section control technology of the appropriate shunt flow channel and the shunt flow channel is used, the static pressure difference between the two flow channels can be eliminated along the axial direction, the distributor uses the high-opening-rate distribution cylinder with uniform holes, and uniform distribution of the gas can be ensured under the condition of no control pressure drop.

[0093] 4. The straight pipe heat exchange pipes are used, the structure is simple and easy to load and unload the catalyst, and the special arrangement mode avoids the problem of excessively high temperature of the catalyst bed between the heat exchange pipes in the traditional arrangement while increasing the catalyst filling volume.

[0094] 5. The radial reactor of the present application has the advantage of doubling the height without increasing the diameter, which is not possessed by the axial reactor, is easy to process and manufacture, is convenient for transportation, and is more suitable for the requirement of large-scale single equipment.

[0095] The above only describes the preferred embodiments of the present application, and does not limit the present application in any form, although the present application has been disclosed as above, however, it is not intended to limit the present application, any skilled person in the art can make some changes or modifications to the above-mentioned technical content as equivalent embodiments without departing from the scope of the technical solution of the present application, as long as it does not depart from the content of the technical solution of the present application, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application are still within the scope of the present application.

Claims

1. A radial flow fixed bed catalytic reactor for carbonylation coupling of CO to produce oxalate, characterized in that: The cylindrical container comprises an upper head, a cylindrical barrel, and a lower head in order from top to bottom, and the outside of the cylindrical container is provided with a reaction gas feed port, a reaction gas discharge port, a heat exchange medium inlet, a heat exchange medium outlet, a catalyst feed port, and a catalyst discharge port; The interior of the cylindrical container is provided with: a porous-walled cylindrical inner distribution tube and a porous-walled cylindrical outer distribution tube, which are coaxially arranged with the cylindrical body and arranged in sequence from the inside to the outside; a catalyst is filled between the inner distribution tube and the outer distribution tube to form a catalytic bed, and a catalyst seal is provided above the catalytic bed; the catalytic bed is divided into an insulating zone and a heat exchange zone from the inside to the outside, and the heat exchange zone is provided with multiple rows of concentrically arranged heat exchange tubes coaxially with the cylindrical body; the heat exchange tubes are connected to the heat exchange medium inlet through a diverter ring tube at the bottom and to the heat exchange medium outlet through a collecting ring tube at the top; the catalyst feed port and the heat exchange medium outlet are located on both sides of the upper head, and the catalyst discharge port and the heat exchange medium inlet are located on both sides of the lower head; The reaction gas feed port is arranged on the upper head and is connected with the porous wall cylindrical inner distribution tube through an expansion joint, and the internal space of the porous wall cylindrical inner distribution tube constitutes a diversion channel for the reaction gas; the upper part of the porous wall cylindrical outer distribution tube is connected to the upper part of the cylindrical barrel through an annular sealing plate, and the annular gap space between the porous wall cylindrical outer distribution tube and the side wall of the cylindrical barrel constitutes a collecting channel, which is connected with the reaction gas discharge port; the reaction gas discharge port is located on the outer side of the cylindrical barrel, on the same side as the catalyst feed port; the reactor is a ∏-type radial reactor; the reaction gas enters from the upper part of the reactor, flows from top to bottom in the diversion channel, passes through the porous wall cylindrical inner distribution tube, enters the insulation zone and heat exchange zone of the catalytic bed in turn, enters the collecting channel through the porous wall cylindrical outer distribution tube, flows from bottom to top in the collecting channel, and finally leaves the reactor through the reaction gas discharge port; The heat exchange tubes are grouped in pairs, with the same number of tubes in the two rows, and are arranged crosswise at intervals. 2 to 6 groups are arranged in the radial direction of the heat exchange zone. The diameter of the heat exchange tubes is 20 mm to 100 mm, and the center distance between the heat exchange tubes in each row is 1.2 to 2.5 times the diameter of the heat exchange tubes. The center distance between two rows of heat exchange tubes in the same group is 1.2 to 3.5 times the diameter of the heat exchange tubes. The difference between the radius of the heat exchange tubes in the inner row of the rear group and the radius of the heat exchange tubes in the outer row of the front group in different groups is 2.5 to 10 times the diameter of the heat exchange tubes. The heat exchange medium enters the reactor through the heat exchange medium inlet of the lower head, and enters the heat exchange tube through the diversion loop. After heat exchange in the catalytic bed, it passes through the collecting loop and flows out of the reactor through the heat exchange medium outlet located at the upper head.

2. The radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate according to claim 1, characterized in that: The thickness of the thermal insulation zone is 50 mm to 300 mm.

3. The radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate according to claim 1, characterized in that: The baffles on both sides of the catalyst seal have no holes; the height of the catalyst seal is 1.2 to 2 times the thickness of the catalytic bed layer.

4. The radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate according to claim 1, characterized in that: The inner distribution tube and the outer distribution tube are provided with small holes at corresponding parts of the catalytic bed layer, and the opening heights of the inner distribution tube and the outer distribution tube are consistent with the height of the upper end of the catalytic bed layer.

5. The radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate according to claim 1, characterized in that: The effective height of the heat exchange tube is consistent with the catalyst filling height.

6. The radial flow fixed-bed catalytic reactor for carbonylation coupling of CO to produce oxalate according to claim 1, characterized in that: The ratio of the cross-sectional area of ​​the diverter channel to the cross-sectional area of ​​the collector channel is 0.5 to 1.0.

Images