Device for producing methyl ethyl carbonate by azeotropic reaction rectification method

Abstract

The invention belongs to the technical field of drug intermediate synthesis, and particularly relates to a device for producing methyl ethyl carbonate by an azeotropic reaction rectification method, which comprises a reaction tower and a purification tower, a tower plate is mounted in the reaction tower, a downcomer and a liquid receiving tray are arranged on two sides of the tower plate, an overflow plate is mounted on the downcomer, and the tower plate is a floating valve plate type tower plate; a catalyst layer is installed on the tower plate, an installation hole is formed in the catalyst layer, the floating valve plate is located in the installation hole, arc-shaped protrusions are arranged on the surface of the catalyst layer, and the height of the arc-shaped protrusion on the side, close to the liquid receiving disc, of the catalyst layer is larger than that of the arc-shaped protrusion on the side, close to the downcomer, of the catalyst layer; the tower plate is simple in structure, through uniform distribution of the arc-shaped protrusions and arrangement of the gaps and the flow guide grooves, a liquid phase is distributed on the tower plate more uniformly and flows stably, the flowing resistance of the liquid phase on the tower plate is reduced, full contact among the liquid phase, a gas phase and a catalyst is promoted, and the catalytic efficiency and the reaction efficiency are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical intermediate synthesis, and specifically relates to a device for producing ethyl methyl carbonate by azeotropic reactive distillation method. Background Art

[0002] Ethyl methyl carbonate is a colorless and transparent liquid with a wide range of uses. In the pharmaceutical industry, ethyl methyl carbonate, sometimes also known as "ethyl methyl carbonate", can be used as a synthetic intermediate for drugs to prepare drugs with specific pharmacological activities. At the same time, due to its good solubility and stability, ethyl methyl carbonate can also be used as a solvent and carrier for pharmaceutical preparations.

[0003] Currently, the common methods for producing ethyl methyl carbonate include phosgene method, oxidative carbonylation method and transesterification method. Among them, the transesterification of dimethyl carbonate and ethanol to synthesize ethyl methyl carbonate under the catalysis of a catalyst has a simple process, less investment in equipment, low toxicity of raw materials and products, no waste discharged during the reaction process that pollutes the environment, and a relatively high yield of ethyl methyl carbonate. It is the main method for industrial production of ethyl methyl carbonate at present.

[0004] Due to the gas-liquid cross-flow contact on the tray for mass transfer and heat transfer between the two phases, the loading of the catalyst significantly increases the flow resistance of the liquid phase and limits the throughput of the reaction tower. At the same time, due to the limitation of the reaction rate in the heterogeneous catalytic process, a longer reaction residence time is required. Due to the limitation of the residence time on the tray, the conversion rate of the raw material dimethyl carbonate is limited, which further increases the difficulty of separating and purifying ethyl methyl carbonate and diethyl carbonate in the subsequent process. Summary of the Invention

[0005] In order to make up for the deficiencies of the prior art, through the uniform distribution, voids and diversion grooves of the arc-shaped protrusions, the distribution of the liquid phase on the tray is made more uniform and stable, the flow resistance of the liquid phase on the tray is reduced, and the full contact between the liquid phase, gas phase and catalyst is promoted, so as to improve the catalytic efficiency and reaction efficiency. The present invention provides a device for producing ethyl methyl carbonate by azeotropic reactive distillation method.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows: The device for producing ethyl methyl carbonate by azeotropic reactive distillation method of the present invention includes a reaction tower and a purification tower. The overhead product of the reaction tower is discharged from the second outlet, passes through a condenser, and then returns to the reaction tower from the third inlet. The raw materials in the reaction tower enter from the second inlet in the middle of the reaction tower. The bottom product of the reaction tower is discharged from the first outlet, passes through a reboiler, and then enters the reaction tower from the first inlet. A part of the bottom product taken out from the reaction tower is sent to the purification tower for separation and purification;

[0007] The reaction tower is divided into a stripping section, a reaction section, and a rectification section from bottom to top. The second inlet is located in the reaction section, the first outlet and the first inlet are located in the stripping section, and the second outlet and the third inlet are located in the rectification section;

[0008] Trays are installed in the reaction tower. Downcomers and liquid receiving trays are arranged on both sides of the tray. An overflow plate is installed on one side of the tray close to the downcomer. Through holes are formed in the tray, and valve trays are installed in the through holes;

[0009] A catalyst layer is installed on the tray in the reaction section. Installation holes are formed in the catalyst layer, and the installation holes correspond to the through holes. An arc-shaped protrusion is arranged on the surface of the catalyst layer, and the arc-shaped protrusions are evenly distributed along the direction from the liquid receiving tray to the downcomer. The height of the arc-shaped protrusion on the side of the catalyst layer close to the liquid receiving tray is greater than the height of the arc-shaped protrusion on the side close to the downcomer.

[0010] Preferably, gaps are provided between the catalyst layer and the tray and inside the catalyst layer.

[0011] Preferably, the catalyst layer is arranged in multiple layers, and each layer of the catalyst layer is independent of each other. The micropore diameter of the catalyst layer gradually increases from top to bottom.

[0012] Preferably, the catalyst layer includes a fixing plate and a catalyst carrier. The catalyst carrier is located in the space inside the fixing plate, and the fixing plate is made of an elastic plastic mesh plate.

[0013] Preferably, the rising height of the valve tray is less than or equal to the thickness of the catalyst layer, and the installation hole is arc-shaped near the edge of the tray.

[0014] Preferably, a flow-promoting ring plate is installed on the inner wall of the tower body. The flow-promoting ring plate corresponds to the tray. Flow guide grooves are formed in the flow-promoting ring plate, and the shape of the flow guide groove is in the shape of a Tesla valve. The forward direction of the Tesla valve is from the liquid receiving tray towards the downcomer direction.

[0015] Preferably, the height of the flow-promoting ring plate is greater than or equal to the height of the overflow plate, and the lower end of the flow-promoting ring plate is in contact with the surface of the tray;

[0016] The height at both ends of the arc-shaped protrusion is less than the height at the middle position of the arc-shaped protrusion, and the end of the arc-shaped protrusion is in contact with the flow-promoting ring plate.

[0017] Preferably, the flow-promoting ring plate is made of a material with a low thermal conductivity, and a heat insulation layer is arranged on the side of the flow-promoting ring plate close to the inner wall of the tower body.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The device for producing ethyl methyl carbonate by azeotropic reactive distillation according to the present invention, by providing a catalyst layer, arc-shaped protrusions and voids, makes the liquid phase on the tray be evenly distributed and stabilized multiple times by the overflow plate and arc-shaped protrusions, enables the liquid phase to flow smoothly on the tray, reduces the liquid-phase flow resistance. At the same time, the liquid phase and the gas phase will fill the voids in the catalyst layer, promoting the mutual contact between the gas phase and the liquid phase, improving the mass transfer effect between the two. At the same time, under the action of the floating valve plate, the gas phase is guided to flow horizontally, thereby promoting the gas phase to enter the voids in the catalyst layer, improving the mass transfer effect of the gas phase and the full contact between the liquid phase and the catalyst, so as to improve the catalytic efficiency and reaction efficiency.

[0020] 2. The device for producing ethyl methyl carbonate by azeotropic reactive distillation according to the present invention, by providing a flow-promoting ring plate and a diversion groove, enables the liquid phase near the wall on the tray to enter the diversion groove and be guided by a diversion valve in the shape of a Tesla valve, accelerating and promoting the flow of the liquid phase near the wall on the tray, preventing the liquid flow near the wall on the tray from being slow or stagnant, which affects the normal flow of the liquid phase on the tray and the catalytic and mass transfer effects of the liquid phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] Figure 1 is a schematic diagram of the principle of the production device of the present invention;

[0023] Figure 2 is a schematic structural diagram of the reaction tower in the production device of the present invention;

[0024] Figure 3 is a schematic structural diagram of the catalyst layer in the reaction tower of the production device of the present invention;

[0025] Figure 4 is a schematic structural diagram of the tray in the reaction tower of the production device of the present invention;

[0026] Figure 5 is a cross-sectional view of a single-layer catalyst layer in the reaction tower of the production device of the present invention;

[0027] Figure 6 is Figure 3 a partial enlarged view of part A in

[0028] Figure 7 is Figure 4 a partial enlarged view of part B in

[0029] In the figure: 1. Reaction tower, 11. First outlet, 12. First inlet, 13. Second inlet, 14. Third inlet, 15. Second outlet, 16. Stripping section, 17. Reaction section, 18. Rectifying section, 2. Tray, 21. Downcomer, 22. Liquid receiving tray, 23. Overflow plate, 24. Through hole, 25. Valve tray, 3. Catalyst layer, 31. Arc-shaped protrusion, 32. Void, 33. Mounting hole, 34. Fixed plate, 341. Catalyst carrier, 4. Flow-promoting ring plate, 41. Flow guide groove, 42. Heat insulation layer, 5. Purification tower. Detailed implementation mode

[0030] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific implementation modes.

[0031] As Figures 1 to 7 shown, the device for producing ethyl methyl carbonate by azeotropic reactive distillation method of the present invention includes a reaction tower 1 and a purification tower 5. The overhead product of the reaction tower 1 is discharged from the second outlet 15, passes through a condenser, and then returns to the reaction tower 1 from the third inlet 14. The raw materials in the reaction tower 1 enter from the second inlet 13 in the middle of the reaction tower 1. The bottom product of the reaction tower 1 is discharged from the first outlet 11, passes through a reboiler, and then enters the reaction tower 1 from the first inlet 12. A part of the bottom product taken out from the reaction tower 1 is sent to the purification tower 5 for separation and purification;

[0032] The reaction tower 1 is divided into a stripping section 16, a reaction section 17 and a rectifying section 18 from bottom to top. The second inlet 13 is located in the reaction section 17, the first outlet 11 and the first inlet 12 are located in the stripping section 16, and the second outlet 15 and the third inlet 14 are located in the rectifying section 18;

[0033] Trays 2 are installed in the reaction tower 1. Downcomers 21 and liquid receiving trays 22 are arranged on both sides of the trays 2. An overflow plate 23 is installed on one side of the tray 2 close to the downcomer 21. Through holes 24 are formed in the tray 2, and valve trays 25 are installed in the through holes 24;

[0034] Catalyst layers 3 are installed on the trays 2 in the reaction section 17. Mounting holes 33 are formed in the catalyst layers 3, and the mounting holes 33 correspond to the through holes 24. Arc-shaped protrusions 31 are arranged on the surface of the catalyst layers 3. The arc-shaped protrusions 31 are evenly distributed along the direction from the liquid receiving tray 22 to the downcomer 21. The height of the arc-shaped protrusions 31 on one side of the catalyst layer 3 close to the liquid receiving tray 22 is greater than the height of the arc-shaped protrusions 31 on one side close to the downcomer 21;

[0035] During production, the raw materials after mixing dimethyl carbonate, ethanol, and an azeotropic agent are fed into the reaction section 17 inside the reaction tower 1 from the second inlet 13 in the middle of the reaction tower 1, enabling dimethyl carbonate and ethanol to react under the catalysis of the catalyst in the catalyst layer 3 within the reaction section 17. After that, a bottom mixture is obtained from the bottom of the reaction tower 1, and a top mixture is obtained from the top of the reaction tower 1:

[0036] Among them, the bottom mixture is diethyl carbonate and methyl ethyl carbonate. The bottom mixture is shunted through a diverter. Part of it is fed as a stream into the purification tower 5 for separation and purification to obtain methyl ethyl carbonate products and diethyl carbonate by-products, and the other part is fed into a reboiler for heating and evaporation and then enters the reaction tower 1 from the first inlet 12;

[0037] Among them, the top mixture is dimethyl carbonate, methanol, and an azeotropic agent. Here, n-pentane is selected as the azeotropic agent. By adding n-pentane, the formation of an azeotrope between dimethyl carbonate and methanol is inhibited, facilitating the separation of the difficult-to-separate dimethyl carbonate and methanol mixture. After that, the separated dimethyl carbonate and n-pentane mixture is re-circulated back into the reaction tower 1, and methanol is taken out as a by-product. At the same time, the top mixture is discharged from the second outlet 15 and enters a condenser for condensation. Then, methanol, the dimethyl carbonate and n-pentane mixture are separated in a liquid separator respectively. After that, the dimethyl carbonate and n-pentane mixture is re-circulated back into the reaction tower 1 from the third inlet 14, and methanol is taken out as a by-product;

[0038] At the same time, when the raw materials enter the reaction section 17, dimethyl carbonate and ethanol in the raw materials react under the catalysis of the catalyst. At the same time, the liquid phase material in the reaction tower 1 will flow from the direction of the liquid receiving tray 22 towards the downcomer 21 on the tray 2. After the liquid phase on the tray 2 crosses the overflow plate 23, it will fall into the liquid receiving tray 22 on the next lower tray 2 from the downcomer 21. During this process, the catalyst layer 3 on the tray comes into contact with the liquid phase material, and the gas phase material in the reaction tower 1 will lift the valve plate 25 on the tray 2 and then flow from bottom to top. The gas phase material heats the liquid phase material, promoting the reaction and the formation of products under the catalysis of the catalyst. And during the process of the gas phase material flowing from bottom to top, it will vaporize and carry away the azeotrope composed of methanol and n-pentane and part of dimethyl carbonate, thus promoting the continuous forward progress of the chemical reaction and the continuous formation of products;

[0039] At the same time, the overflow plate 23 on the tower plate 2 is used to evenly distribute and overflow the liquid-phase material, so that the liquid-phase material can flow smoothly and evenly on the tower plate 2, avoiding excessive or insufficient liquid-phase material locally on the tower plate 2, ensuring that the catalyst in the catalyst layer 3 on the tower plate 2 can fully contact the raw material, improve the catalytic efficiency of the catalyst, and ensure the stability and efficiency of the reaction in the tower. At the same time, the multiple groups of arc-shaped protrusions 31 arranged on the catalyst layer 3 will distribute and stabilize the liquid-phase material flowing on the tower plate 2 for multiple times, so that the liquid-phase material can flow smoothly. At the same time, since the liquid-phase material is blocked and overflowed by the arc-shaped protrusions 31, the flow speed of the liquid-phase material on the tower plate 2 will be hindered and slowed down, prolonging the time that the liquid-phase material stays on the tower plate 2, increasing the contact time between the raw material and the catalyst, and improving the reaction conversion rate and reaction efficiency;

[0040] At the same time, when the liquid-phase material falls from the downcomer 21 on the upper tower plate 2 to the liquid receiving plate 22, the impact of the falling liquid material will cause the liquid-phase material at the liquid receiving plate 22 to fluctuate greatly. Then, when the liquid-phase material flows from the liquid receiving plate 22 to the tower plate 2, the liquid-phase material on the side of the tower plate 2 close to the liquid receiving plate 22 is relatively unstable, and the flow of the liquid-phase material fluctuates, which affects the catalytic reaction efficiency and the mass transfer effect between the gas phase and the liquid phase. Therefore, the height of the arc-shaped protrusion 31 near the overflow plate 23 is set higher, and the higher arc-shaped protrusion 31 is used to Unstable liquid-phase materials are intercepted, blocked and smoothed, thereby weakening the fluctuation of the liquid-phase materials on the tower plate 2 near the liquid receiving plate 22 as much as possible, ensuring the smooth flow and uniform distribution of the liquid-phase materials on the tower plate 2, and improving the catalytic efficiency and reaction effect of the reaction section 17. At the same time, since the height of the arc-shaped protrusion 31 near the overflow plate 23 is relatively low, the liquid-phase materials near the overflow plate 23 are less obstructed by the arc-shaped protrusion 31, that is, the flow resistance of the liquid-phase materials is relatively small, which facilitates the liquid-phase materials to pass over the overflow plate 23 and enter the next tower plate 2 from the downcomer 21.

[0041] As an embodiment of the present invention, a gap 32 is provided between the catalyst layer 3 and the tray 2 and inside the catalyst layer 3;

[0042] When the gaseous material flowing from bottom to top in the reaction tower 1 contacts the catalyst layer 3, the gaseous material will be buffered and blocked by the gap 32, so that the residence time of the gaseous material in the liquid material on the tray 2 is prolonged, the mass transfer effect between the gas phase and the liquid phase is increased, and the operation effect and stability in the reaction tower 1 are improved;

[0043] Meanwhile, since voids 32 are provided inside the catalyst layer 3 and between the catalyst layer 3 and the tray 2, the liquid-phase material on the tray 2 can fill these voids 32, so that the liquid-phase material can be in full contact with the catalyst layer 3, improving the catalytic efficiency and effect of the catalyst. At the same time, the liquid-phase material in the voids 32 contacts the upward-flowing gas-phase material in the voids 32, improving the mass transfer effect between the liquid phase and the gas phase, and enabling the gas-phase material to agitate the liquid-phase material in the voids 32, promoting the flow of the liquid-phase material in the voids 32, accelerating the diffusion of the reaction products out of the catalyst layer 3, and improving the catalytic efficiency;

[0044] Meanwhile, since voids 32 are provided inside the catalyst layer 3 and between the catalyst layer 3 and the tray 2, the liquid-phase material can flow along the voids 32 in the catalyst layer 3, so that the liquid-phase material can smoothly pass through the catalyst layer 3, making the fluidity of the liquid-phase material better, and enabling the gas-phase material to rise smoothly and carry away the reaction products, preventing the plate pressure drop in the reaction section 17 from being too large and affecting the normal operation of the reaction tower 1.

[0045] As an embodiment of the present invention, the catalyst layer 3 is provided in multiple layers, and each layer of the catalyst layer 3 is independent of each other, and the micropore diameter on the catalyst layer 3 gradually increases from top to bottom;

[0046] By providing multiple layers of the catalyst layer 3 and making each layer of the catalyst layer 3 independent of each other, the volume of a single catalyst layer 3 is relatively small, so that the thickness of a single layer of the catalyst layer 3 is relatively small, that is, the density of the catalyst is relatively small and loose, which is convenient for the liquid-phase material and the gas-phase material to immerse and penetrate the catalyst layer 3, enabling the liquid-phase material and the gas-phase material to fully contact the catalyst, and improving the catalytic efficiency and the mass transfer efficiency;

[0047] At the same time, since the micropore diameter on the surface of the single catalyst layer 3 close to the tray 2 in the catalyst layer 3 is relatively large, the liquid-phase material and the gas-phase material will be relatively more likely to enter the catalyst layer 3. After that, when the gas-phase material continues to flow upward, affected by the decrease in the micropore diameter on the surface of the upper single catalyst layer 3, the residence time of the gas-phase material in the catalyst layer 3 increases, improving the mass transfer effect of the gas-phase material in the catalyst layer 3, and facilitating the gas-phase material to carry away the reaction products, improving the separation efficiency.

[0048] As an embodiment of the present invention, the catalyst layer 3 includes a fixing plate 34, and the catalyst carrier 341 is located in the space inside the fixing plate 34, and the fixing plate 34 is made of an elastic plastic mesh plate;

[0049] Since the fixing plate 34 is an elastic plastic mesh plate, any single-layer catalyst layer 3 can be bent or curled, so that when the staff installs, disassembles, replaces and maintains the catalyst layer 3 in the reaction section 17, the single-layer catalyst layer 3 can be deformed and rolled up conveniently, reducing the space occupied by the single-layer catalyst layer 3 relatively, so that the staff can take out and send the rolled-up single-layer catalyst layer 3 from the inspection manhole on the reaction tower 1, thus facilitating the disassembly and installation of the catalyst layer 3;

[0050] At the same time, since the single-layer catalyst layer 3 can be deformed and bent and the catalyst layers 3 are relatively independent of each other, after the catalyst layer 3 is installed on the tray 2, the catalyst layers 3 will be locked and tightened with each other, preventing the single-layer catalyst layer 3 from being relatively thin and light, resulting in the single-layer catalyst layer 3 being lifted or jolted by the rising gas-phase material, affecting the normal operation in the reaction section 17;

[0051] At the same time, since the single-layer catalyst layer 3 is relatively thin and light and the micropores provided on the surface of the single-layer catalyst layer 3 eliminate the liquid droplets carried by the gas-phase material during the rising process, partial demisting effect is produced.

[0052] As an embodiment of the present invention, the rising height of the valve tray 25 is less than or equal to the thickness of the catalyst layer 3, and the mounting hole 33 is arc-shaped near the edge of the tray 2;

[0053] Since the rising height of the valve tray 25 is less than or equal to the thickness of the catalyst layer 3, when the gas-phase material rising in the reaction tower 1 passes through the valve tray 25, the gas-phase material is guided to flow horizontally. At this time, due to the gaps 32 provided between the catalyst layer 3 and the tray 2 and between the inner walls of the catalyst layer 3, the gas-phase material flowing horizontally will be guided into the gaps 32, increasing the residence time of the gas-phase material between the liquid-phase materials and improving the mass transfer effect between the two;

[0054] At the same time, since the mounting hole 33 is arc-shaped near the edge of the tray 2, the gas-phase material flowing horizontally is further guided by the arc shape, prompting the gas-phase material to enter the gap 32 and preventing the gas-phase material from rising directly after being blocked, affecting the mutual contact and mass transfer effect between the gas-phase material and the liquid-phase material.

[0055] As an embodiment of the present invention, a flow-promoting ring plate 4 is installed on the inner wall of the tower body. The flow-promoting ring plate 4 corresponds to the tray 2. The flow-promoting ring plate 4 is provided with a diversion groove 41. The shape of the diversion groove 41 is in the shape of a Tesla valve, and the forward direction of the Tesla valve is from the liquid receiving tray 22 towards the downcomer 21;

[0056] Since the flow-promoting ring plate 4 is provided with a diversion groove 41, and the diversion groove 41 is in the shape of a Tesla valve, the liquid-phase material near the inner wall of the tray 2 will contact and enter the diversion groove 41. Through the characteristics of the Tesla valve shape, the liquid-phase material flowing from the liquid receiving tray 22 towards the downcomer 21 has the same forward direction as the diversion groove 41, which will cause the liquid-phase material near the wall of the tray 2 to enter the diversion groove 41. Furthermore, this part of the liquid-phase material will flow along the forward direction of the diversion groove 41 in the shape of a Tesla valve, facilitating and promoting the flow of the liquid-phase material near the inner wall of the tray 2, thereby improving the problem that the liquid-phase material near the inner wall of the tray 2 flows relatively slowly or stagnates severely, and improving the separation efficiency.

[0057] As an embodiment of the present invention, the height of the flow-promoting ring plate 4 is greater than or equal to the height of the overflow plate 23, and the lower end of the flow-promoting ring plate 4 is in contact with the surface of the tray 2;

[0058] The heights at both ends of the arc-shaped protrusion 31 are less than the height at the middle position of the arc-shaped protrusion 31, and the ends of the arc-shaped protrusion 31 are in contact with the flow-promoting ring plate 4;

[0059] Since the heights at both ends of the arc-shaped protrusion 31 are less than the height at the middle position of the arc-shaped protrusion 31, when the liquid-phase material on the tray 2 is blocked and evenly distributed by the arc-shaped protrusion 31, relatively more liquid-phase material will be distributed near both ends of the arc-shaped protrusion 31, thereby promoting a relative increase in the liquid-phase material near the inner wall of the tray 2, that is, promoting the liquid-phase material to be near the inner wall of the tower body, thereby further accelerating the flow rate of the liquid-phase material near the wall of the tray 2, avoiding a decrease or stagnation in the flow rate of the liquid-phase material near the wall of the tray 2, and thus ensuring a relatively high mass transfer efficiency between the liquid-phase material near the wall of the tray 2 and the catalyst layer 3, promoting an increase in the catalytic efficiency, and thereby improving the separation efficiency.

[0060] As an embodiment of the present invention, the flow-promoting ring plate 4 is made of a material with a relatively low thermal conductivity, and a heat insulation layer 42 is provided on the side of the flow-promoting ring plate 4 close to the inner wall of the tower body;

[0061] Since the thermal conductivity of the flow-promoting ring plate 4 is relatively low, and a heat insulation layer 42 is provided between the flow-promoting ring plate 4 and the inner wall of the tower body, the liquid-phase material on the tray 2 does not contact or has little contact with the inner wall of the tower body, thereby reducing the heat conduction between the liquid-phase material on the tray 2 and the tower body, resulting in a decrease in the temperature of the liquid-phase material near the wall of the tray 2, which affects the efficiency and effect of the raw material reaction in the reaction tower 1. At the same time, since the height of the flow-promoting ring plate 4 is greater than or equal to the height of the overflow plate 23, the height of the liquid-phase material existing on the tray 2 will be less than or equal to the height of the flow-promoting ring plate 4, fully avoiding the liquid-phase material near the wall of the tray 2 from crossing the flow-promoting ring plate 4 and contacting the inner wall of the tower body, thereby ensuring the catalytic efficiency and effect of the catalyst in the reaction section 17, and ensuring the separation efficiency of the reaction tower 1.

[0062] The specific work process is as follows:

[0063] During production, the raw materials after mixing dimethyl carbonate, ethanol and the azeotropic agent are fed into the reaction section 17 in the reaction tower 1 from the second inlet 13 in the middle of the reaction tower 1, so that dimethyl carbonate and ethanol react under the catalysis of the catalyst in the catalyst layer 3 in the reaction section 17. After that, the bottom mixture is obtained from the bottom of the reaction tower 1, and the top mixture is obtained from the top of the reaction tower 1:

[0064] Among them, the bottom mixture is diethyl carbonate and methyl ethyl carbonate. The bottom mixture is shunted by a diverter. Part of it is sent as a logistics to the purification tower 5 for separation and purification to obtain methyl ethyl carbonate products and diethyl carbonate by-products, and the other part is sent to a reboiler for heating and evaporation and then enters the reaction tower 1 from the first inlet 12;

[0065] Among them, the top mixture is dimethyl carbonate, methanol and the azeotropic agent. Here, the azeotropic agent is selected as n-pentane. After that, the dimethyl carbonate and n-pentane mixture is refluxed back to the reaction tower 1 again, and methanol is taken out as a by-product;

[0066] At the same time, when the raw materials enter the reaction section 17, dimethyl carbonate and ethanol in the raw materials react under catalysis. The catalyst layer 3 contacts the liquid-phase material, and the gas-phase material lifts the valve plate 25 and then flows upward from bottom to top. The gas-phase material vaporizes and takes away the azeotrope composed of methanol and n-pentane and part of dimethyl carbonate;

[0067] At the same time, the overflow plate 23 on the tray 2 is used to evenly distribute and overflow the liquid-phase material, so that the liquid-phase material can flow smoothly and evenly on the tray 2. At the same time, the arc-shaped protrusion 31 evenly distributes and stabilizes the flowing liquid-phase material for many times, so that the liquid-phase material can flow smoothly. At the same time, due to the blockage and overflow of the liquid-phase material by the arc-shaped protrusion 31, the flow rate of the liquid-phase material on the tray 2 will be hindered and slowed down, and the residence time of the liquid-phase material on the tray 2 will be extended;

[0068] At the same time, due to the impact generated by the falling of the liquid material, when the liquid-phase material flows from the liquid receiving tray 22 to the tray 2, the liquid-phase material near the liquid receiving tray 22 is relatively unstable and the flow of the liquid-phase material will fluctuate. The height of the arc-shaped protrusion 31 close to the overflow plate 23 is set higher to intercept, block and smooth the unstable liquid-phase material. At the same time, since the height of the arc-shaped protrusion 31 close to the overflow plate 23 is lower, the liquid-phase material near the overflow plate 23 is less hindered by the arc-shaped protrusion 31, that is, the flow resistance of the liquid-phase material is smaller, which is convenient for the liquid-phase material to enter the next tray 2 from the downcomer 21 after passing over the overflow plate 23;

[0069] When the gas-phase material flowing upward from the bottom in the reaction tower 1 contacts the catalyst layer 3, the gas-phase material will be buffered and obstructed by the voids 32, prolonging the residence time of the gas-phase material in the liquid-phase material on the tray 2;

[0070] Meanwhile, since voids 32 are provided inside the catalyst layer 3 and between the catalyst layer 3 and the tray 2, the liquid-phase material on the tray 2 can fill these voids 32, thereby enabling the liquid-phase material to come into full contact with the catalyst layer 3. At the same time, the liquid-phase material in the voids 32 contacts the upward-flowing gas-phase material in the voids 32, improving the mass transfer effect between the liquid phase and the gas phase, and causing the gas-phase material to agitate the liquid-phase material in the voids 32;

[0071] Meanwhile, since voids 32 are provided inside the catalyst layer 3 and between the catalyst layer 3 and the tray 2, the liquid-phase material can flow along the voids 32 in the catalyst layer 3, enabling the liquid-phase material to smoothly pass through the catalyst layer 3, making the fluidity of the liquid-phase material better, and enabling the gas-phase material to rise smoothly and carry away the reaction products;

[0072] By providing multiple catalyst layers 3 and making each catalyst layer 3 independent of each other, the volume of a single catalyst layer 3 is relatively small, so that the thickness of a single catalyst layer 3 is relatively small, that is, the density of the catalyst is relatively small and loose, facilitating the immersion and penetration of the liquid-phase material and the gas-phase material into the catalyst layer 3, and enabling the liquid-phase material and the gas-phase material to fully contact the catalyst;

[0073] Meanwhile, since the micropore diameter on the surface of the single catalyst layer 3 close to the tray 2 in the catalyst layer 3 is relatively large, the liquid-phase material and the gas-phase material will be relatively more likely to enter the catalyst layer 3. After that, when the gas-phase material continues to flow upward, affected by the decrease in the micropore diameter on the surface of the upper single catalyst layer 3, the residence time of the gas-phase material in the catalyst layer 3 increases;

[0074] Since the fixing plate 34 is an elastic plastic mesh plate, any single catalyst layer 3 can be bent and curled. When the staff installs, disassembles, replaces, and maintains the catalyst layer 3 in the reaction section 17, the single catalyst layer 3 can be conveniently deformed and rolled up, reducing the space occupied by the single catalyst layer 3, so that the staff can take out and send in the rolled-up single catalyst layer 3 from the inspection manhole on the reaction tower 1;

[0075] Since the height that the floating valve plate 25 rises is less than or equal to the thickness of the catalyst layer 3, after the gas-phase material rising upward in the reaction tower 1 passes through the floating valve plate 25, the gas-phase material is guided by the floating valve plate 25 to flow horizontally. At this time, due to the gaps 32 provided between the catalyst layer 3 and the tray 2 and between the inner walls of the catalyst layer 3, the gas-phase material flowing horizontally will be guided into the gaps 32;

[0076] Meanwhile, since the installation holes 33 are arc-shaped near the edge of the tray 2, the arc-shaped edges of the installation holes further guide the gas-phase material flowing horizontally, promoting the gas-phase material to enter the gaps 32;

[0077] Since the flow-promoting ring plate 4 is provided with flow guide grooves 41, and the flow guide grooves 41 are in the shape of a Tesla valve, the liquid-phase material near the inner wall on the tray 2 will contact and enter the flow guide grooves 41. Through the characteristics of the Tesla valve shape, the liquid-phase material flowing from the liquid receiving tray 22 towards the downcomer 21 has the same forward direction as the flow guide grooves 41, which will cause the liquid-phase material near the inner wall on the tray 2 to enter the flow guide grooves 41. Then, this part of the liquid-phase material will flow along the forward direction of the flow guide grooves 41 in the shape of a Tesla valve, facilitating and promoting the flow of the liquid-phase material near the inner wall on the tray 2;

[0078] Since the heights at both ends of the arc-shaped protrusion 31 are less than the height at the middle position of the arc-shaped protrusion 31, when the liquid-phase material on the tray 2 is blocked and evenly distributed by the arc-shaped protrusion 31, the liquid-phase material distributed near both ends of the arc-shaped protrusion 31 will be relatively more, thereby promoting the relative increase of the liquid-phase material near the inner wall of the tower body on the tray 2, that is, promoting the liquid-phase material to be close to the inner wall of the tower body, and further accelerating the flow rate of the liquid-phase material near the inner wall on the tray 2;

[0079] Since the heat conduction coefficient of the flow-promoting ring plate 4 is relatively low, and a heat insulation layer 42 is provided between the flow-promoting ring plate 4 and the inner wall of the tower body, the liquid-phase material on the tray 2 does not contact or has little contact with the inner wall of the tower body, reducing the heat conduction between the liquid-phase material on the tray 2 and the tower body. At the same time, since the height of the flow-promoting ring plate 4 is greater than or equal to the height of the overflow plate 23, the height of the liquid-phase material existing on the tray 2 will be less than or equal to the height of the flow-promoting ring plate 4, fully avoiding the liquid-phase material near the inner wall on the tray 2 from crossing over the flow-promoting ring plate 4 and contacting the inner wall of the tower body.

[0080] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. An apparatus for producing ethyl methyl carbonate by azeotropic reactive distillation, comprising a reaction column (1) and a purification column (5). The overhead product of the reaction column (1) is discharged from the second outlet (15), and after passing through a condenser, it is refluxed into the reaction column (1) from the third inlet (14). The raw materials in the reaction column (1) enter from the second inlet (13) in the middle of the reaction column (1). The bottom product of the reaction column (1) is discharged from the first outlet (11), and after passing through a reboiler, it enters the reaction column (1) from the first inlet (12). A part of the bottom product taken out from the reaction column (1) is sent to the purification column (5) for separation and purification; The reaction column (1) is divided into a stripping section (16), a reaction section (17), and a rectifying section (18) from bottom to top. The second inlet (13) is located in the reaction section (17), the first outlet (11) and the first inlet (12) are located in the stripping section (16), and the second outlet (15) and the third inlet (14) are located in the rectifying section (18); Trays (2) are installed in the reaction column (1). Downcomers (21) and receiving trays (22) are arranged on both sides of the trays (2). An overflow plate (23) is installed on one side of the trays (2) close to the downcomer (21). Through holes (24) are formed in the trays (2), and valve trays (25) are installed in the through holes (24); It is characterized in that: A catalyst layer (3) is installed on the trays (2) in the reaction section (17). Mounting holes (33) are formed in the catalyst layer (3), and the mounting holes (33) correspond to the through holes (24). Arc-shaped protrusions (31) are arranged on the surface of the catalyst layer (3), and the arc-shaped protrusions (31) are evenly distributed along the direction from the receiving tray (22) to the downcomer (21). The height of the arc-shaped protrusions (31) on the side of the catalyst layer (3) close to the receiving tray (22) is greater than the height of the arc-shaped protrusions (31) on the side close to the downcomer (21).

2. The device for producing ethyl methyl carbonate by azeotropic reactive distillation according to claim 1, characterized in that: Gaps (32) are provided between the catalyst layer (3) and the trays (2) and inside the catalyst layer (3).

3. The device for producing ethyl methyl carbonate by azeotropic reactive distillation according to claim 2, characterized in that: The catalyst layer (3) is provided with multiple layers, and each layer of the catalyst layer (3) is independent of each other. The micropore diameter of the catalyst layer (3) gradually increases from top to bottom.

4. The apparatus for producing ethyl methyl carbonate by azeotropic reactive distillation according to claim 3, wherein: The catalyst layer (3) includes a fixing plate (34) and a catalyst carrier (341). The catalyst carrier (341) is located in the space inside the fixing plate (34). The fixing plate (34) is made of an elastic plastic mesh plate.

5. The device for producing ethyl methyl carbonate by azeotropic reactive distillation according to claim 2, wherein: The rising height of the valve tray (25) is less than or equal to the thickness of the catalyst layer (3). The mounting holes (33) are arc-shaped near the edge of the trays (2).

6. The device for producing ethyl methyl carbonate by azeotropic reactive distillation according to claim 1, characterized in that: Flow-promoting ring plates (4) are installed on the inner wall of the column. The flow-promoting ring plates (4) correspond to the trays (2). Flow guiding grooves (41) are formed in the flow-promoting ring plates (4), and the shape of the flow guiding grooves (41) is in the shape of a Tesla valve. The forward direction of the Tesla valve is from the receiving tray (22) towards the downcomer (21).

7. The device for producing ethyl methyl carbonate by azeotropic reactive distillation according to claim 6, characterized in that: The height of the flow-promoting ring plate (4) is greater than or equal to the height of the overflow plate (23), and the lower end of the flow-promoting ring plate (4) is in contact with the surface of the tray (2). The height at both ends of the arc-shaped protrusion (31) is less than the height at the middle position of the arc-shaped protrusion (31), and the end of the arc-shaped protrusion (31) is in contact with the flow-promoting ring plate (4).

8. The apparatus for producing ethyl methyl carbonate by azeotropic reactive distillation according to claim 6, characterized in that: The flow-promoting ring plate (4) is made of a material with a relatively low thermal conductivity, and a heat insulation layer (42) is provided on the side of the flow-promoting ring plate (4) close to the inner wall of the tower body.

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