Micro-channel cyclic carbonate preparation reaction heat integration device and method

Abstract

The invention relates to a reaction heat integration device and method for preparing cyclic carbonate through a microchannel. The device comprises a reaction unit, a heat integration unit and a catalyst separation unit. In order to realize integrated utilization of reaction heat, the reaction unit comprises a bubbling bed reactor, a micro-channel reactor and a heat integration system, raw materials CO2 and alkylene oxide react in the bubbling bed reactor, reaction heat is absorbed by the micro-channel reactor and a heat removal medium of the heat integration unit, and the reaction heat is recovered by the micro-channel reactor. After being heated and pressurized, the heat is supplied to an evaporator of the catalyst separation unit, so that the reaction efficiency is ensured, the reaction heat integrated utilization of the cyclic carbonate is realized, the preparation energy consumption of the cyclic carbonate is greatly reduced, the reaction heat integrated utilization efficiency is improved, and a high-efficiency low-carbon preparation technology is provided for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of carbonate preparation and separation, and relates to a device and a method for synthesizing cyclic carbonate from alkylene oxide via microchannel thermal integration. Background Art

[0002] Cyclic carbonate is a heterocyclic ketone with the molecular formula shown below. It is widely used in printing and dyeing, plastics, gas separation, polymer synthesis and electrochemistry. It can replace ethylene oxide (EO) in ethoxylation reactions. Aliphatic bio-based polycarbonate with carbonate as the basic structural unit is used as a biodegradable material. It also has a high dielectric constant and is a key solvent in lithium battery electrolytes. It is mainly prepared by cycloaddition of CO2 and alkylene oxides and has significant low-carbon properties. At the same time, its downstream various carbonates are key components of current new energy electrolyte solvents, including dimethyl carbonate (DMC), ethyl methyl carbonate, diethyl carbonate, fluoroethylene carbonate, vinylene carbonate, etc., and the market is developing rapidly.

[0003]

[0004] The preparation of carbonates by CO2 cycloaddition has a typical chemical carbon fixation effect, which can theoretically achieve 100% chemical carbon fixation, with an annual demand growth rate of >30%, and is expected to reach 4 million tons in 2025. Up to now, a lot of research has been carried out at home and abroad on the preparation of carbonates by CO2 cycloaddition, but it has always faced technical difficulties such as the flammability and explosion of alkylene oxides, the easy loss of control at high temperature, and the difficulty in utilizing the reaction heat. In order to solve the problem of complete conversion of alkylene oxides, patent CN 105777543 A discloses a method and process system for preparing chain carbonates and co-producing diols by using epoxides and CO2, using a fixed bed or bubbling bed tubular reactor filled with a heterogeneous solid catalyst, and the process system has strong continuity and stable and reliable production. However, when the alkylene oxide is converted to a certain extent, the reaction rate drops sharply, and a longer residence time and a smaller reaction space velocity are required to completely convert the material, and the production efficiency is low. Patent CN 106478586 A discloses a synthesis process of ethylene carbonate. After the reactants ethylene oxide and CO2 are reacted in a synthesis reactor (fixed bed, bubbling bed or fluidized bed), part of the liquid phase circulation flow (50%-99%) is further reacted in the synthesis reactor. This process solves the problems of incomplete reaction and difficult recovery of ethylene oxide, but a large amount of liquid phase flow circulation is produced, and the energy consumption is high.

[0005] In terms of promoting the mild conversion of alkylene oxide, CN 102464521B and CN 103724315 A have successively announced a device and method for strengthening the synthesis of cyclic carbonates by microreactors, which greatly improve the space-time yield and selectivity of cyclic carbonates by taking advantage of the fast mass and heat transfer rate of the microchannel reaction system. However, since the process adopts a system combination of a micromixer and a microchannel reactor, the reaction design and processing are difficult, the pressure drop is high, and the volume efficiency of the reactor has not been significantly improved, which limits its industrial application prospects. Similarly, CN 114478462A, CN 115960071B and CN117777087 A have respectively improved a device and method for preparing cyclic carbonates by microchannel reaction. By using low eutectic ionic liquids and microchannel reactors with different tube diameters, they successfully broke through the rate limitations of the cycloaddition reaction rate and gas-liquid mass transfer and achieved a mild conversion of CO2 and alkylene oxides. However, the reaction heat was not utilized and the energy utilization efficiency still needs to be improved. At the same time, the flux of the microchannel reactor is low, and it cannot be used for large-scale industrial applications, and is not suitable for the preparation of bulk chemical carbonates.

[0006] In terms of the integrated utilization of carbonate reaction heat, CN217872958U provides a carbonate device steam recovery and utilization device, which can recover the excess steam generated in the carbonate device, but does not involve a method for transferring and converting the reaction heat. CN112142599B provides a low-energy consumption, green carbonate product production method and system, which uses a two-stage reactor in series to prepare ethylene carbonate (EC), and then uses heat pump distillation technology to achieve the preparation and separation of DMC reaction distillation, but does not involve the integrated utilization of cyclic carbonate (ethylene carbonate) reaction heat.

[0007] In summary, in order to further improve the preparation efficiency and energy utilization of cyclic carbonates, how to achieve efficient integrated utilization of reaction heat in the preparation process of cyclic carbonates while stably achieving complete conversion of alkylene oxides is a key technical problem that needs to be solved in this field. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a microchannel cyclic carbonate reaction heat integration device and method. The present invention uses a microchannel reactor to deepen the cycloaddition while taking into account the reaction heat integration method, which can continuously and efficiently achieve the stable conversion of alkylene oxide, reaction heat removal and reuse, taking into account the technical requirements of reaction control and heat integration utilization, simplifying the cyclic carbonate preparation process, and greatly improving the integration of the device and the efficiency of the technical method.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In the first aspect, the present invention provides a microchannel heat integration device for preparing cyclic carbonate reaction, which mainly includes a reaction unit, a heat integration unit and a catalyst separation unit connected in sequence, wherein the reaction unit includes a bubbling bed reactor and a microchannel reactor connected to each other; the heat integration unit includes a gas-liquid separation tank and at least one compressor connected to each other; the catalyst separation unit includes a flash tank and an evaporator connected in series, and the evaporator is provided with a heater for vaporization. Among them, the heaters of the evaporator are two in series or in parallel, one of which uses steam heating as a backup, and is used for heat compensation when there is not enough reaction heat at the start-up and the reaction fluctuation is unstable; the air inlet of the other is connected to the compressor outlet of the heat integration unit through a pipeline, and heat is supplied to the heater through a heat exchange medium; to ensure the reaction heat integration efficiency, the compressor is at least two in series.

[0011] In the present invention, the microchannel reactor is any one of a plate type, a tubular type and a spiral structure, and the microchannel reactor is provided with a hot material channel and a cold material channel, and the hot material channel and the cold material channel are respectively provided with a liquid inlet and a liquid outlet. In order to realize the integrated utilization of reaction and reaction heat, at least one liquid inlet, at least one air inlet and at least one liquid outlet are provided on the upper part of the bubbling bed reactor, wherein the liquid outlet of the bubbling bed reactor is connected to the liquid inlet of the hot material channel of the microchannel reactor by a pipeline, and the air inlet is connected to the gas distributor in the bubbling bed reactor. The liquid outlet of the hot material channel of the microchannel reactor is connected to the upper liquid inlet of the bubbling bed reactor and the liquid inlet of the gas-liquid separation tank by pipelines. A mechanical pump and a cooler are provided on the pipeline connecting the liquid outlet of the hot material channel of the microchannel reactor and the upper liquid inlet of the bubbling bed reactor.

[0012] In the connection method between the heat integration unit and the reaction unit and the catalyst separation unit, the liquid inlet of the gas-liquid separation tank is connected to the liquid outlet of the cold material channel of the microchannel reactor through a pipeline, the heater is connected to the compressor outlet of the heat integration unit through a pipeline, and the liquid outlet of the heater is connected to the liquid inlet of the cold material channel of the microchannel reactor through a pipeline.

[0013] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0014] As a preferred technical solution of the present invention, the bubbling bed reactor of the present invention is the main equipment for the cycloaddition reaction of CO2 and alkylene oxide. In order to ensure that the alkylene oxide is completely converted after passing through the bubbling bed reactor and the microchannel reactor, the bubbling bed reactor is provided with two liquid inlets, namely an upper liquid inlet and a middle liquid inlet, wherein the upper liquid inlet is connected to the liquid outlet of the cooler through a pipeline, and the middle liquid inlet is connected to the liquid outlet of the evaporator through a pipeline; a mechanical pump is provided on the connecting pipeline between the liquid outlet of the bubbling bed reactor and the liquid inlet of the hot material channel of the microchannel reactor.

[0015] The present invention utilizes the bubbling bed reactor to realize the conversion of most of the alkylene oxides, and the remaining small amount of alkylene oxide is enhanced by mass transfer in the microchannel reactor to achieve complete conversion, and the heat released by the reaction is absorbed and taken out by the heat exchange medium of the cold material channel of the microchannel reactor by the enhanced effect of mass transfer and heat transfer of the microchannel in the microchannel reactor, and the flash tank and compressor device of the heat integration unit are separated and pressurized to provide heat supply for the evaporator, which greatly improves the reaction heat integration efficiency. To ensure the conversion efficiency of alkylene oxide, the air inlet of the bubbling bed reactor is connected to the gas distributor in the bubbling bed reactor, and the gas distributor of the bubbling bed reactor is installed at a height of at least 0.3m from the liquid outlet of the bubbling bed reactor. At the same time, in order to further realize the integrated utilization efficiency of reaction heat, the inside and outside of the reaction unit are no longer provided with additional heat exchange devices except the device system, and the bottom liquid outlet of the bubbling bed reactor directly enters the microchannel reactor after the mechanical pump on the pipeline is pressurized to carry out deep reaction and heat exchange removal.

[0016] As a preferred technical solution of the present invention, the material of the microchannel reactor is selected from any one of stainless steel, alloy, ceramic, polyester or silicon carbide glass, or a combination of at least two thereof; the equivalent inner diameter of the hot material channel of the microchannel reactor is 10um to 19mm.

[0017] As a preferred technical solution of the present invention, in order to ensure the reaction efficiency of the bubbling bed and the stability of the bed temperature, the two liquid inlets on the upper part of the bubbling bed reactor in the present invention are at different positions, wherein the upper liquid inlet is arranged at the uppermost part of the bubbling bed reactor and is connected to the hot material channel outlet of the microchannel reactor through a pipeline; the middle liquid inlet is arranged in the upper middle part of the bubbling bed reactor and is connected to the bottom liquid outlet of the evaporator through a pipeline.

[0018] In a second aspect, the present invention provides a method for realizing heat integration of cyclic carbonate reaction using the device, the method comprising the following steps:

[0019] (a) The raw materials CO2 and alkylene oxide are introduced into the bubbling bed reactor from the bottom air inlet and the middle liquid inlet, respectively, and a cycloaddition reaction occurs under the action of a catalyst; to ensure the conversion efficiency of alkylene oxide, the catalyst is any one of ionic liquid imidazolium bromide, pyridinium bromide, quaternary phosphonium bromide, quaternary ammonium bromide, or a combination of any one of them and any one or more of ZnBr2, CuBr2, NiBr2 and KI metal salts. To improve the utilization efficiency of the raw materials, the feed ratio of CO2 to alkylene oxide is controlled at (1.01-1.5) / 1;

[0020] (b) the liquid phase discharge of the unreacted alkylene oxide and dissolved CO2 at the bottom of the bubbling bed reactor is pressurized and introduced into the microchannel reactor for further cycloaddition reaction, wherein the equivalent inner diameter of the hot material channel of the microchannel reactor is 10um-19mm;

[0021] (c) After the liquid phase passes through the microchannel reactor, 70% to 90% of the liquid phase is pressurized by a mechanical pump and cooled by a cooler, and then sent to the upper liquid inlet of the bubbling bed reactor for recycling, and the remaining 10% to 30% is pressurized by the mechanical pump and then taken out and sent to the catalyst separation unit; wherein the cooling medium of the cooler is hot water at 20-40° C., and the temperature of the bubbling bed reactor is controlled by the flow rate of the hot water;

[0022] (d) In order to realize the integrated utilization of reaction heat, a heat exchange medium at 60-80° C. is introduced into the cold material channel of the microchannel reactor, and the reaction temperature of the microchannel reactor is controlled by the flow rate of the heat exchange medium; the heated heat exchange medium passes through the gas-liquid separation tank and the compressor of the heat integration unit, and is then sent to the heater of the evaporator of the catalyst separation unit for use.

[0023] The concentration of the catalyst is 0.5% to 12% of the mass of the feed alkylene oxide, and the catalyst is preferably an imidazolium bromide, pyridinium bromide, quaternary phosphine bromide, or quaternary ammonium bromide type ionic liquid, and the catalyst concentration is preferably 3% to 12%; the catalyst can also be at least two combinations of imidazolium bromide, pyridinium bromide, quaternary phosphine bromide, or quaternary ammonium bromide type ionic liquid and any one of ZnBr2, CuBr2, NiBr2 and KI metal salts, for example, it can be an imidazolium bromide / ZnBr2, pyridinium bromide / CuBr2, or quaternary phosphine bromide / KI binary composite catalyst, or it can be a quaternary phosphine bromide / ZnBr2 / KI ternary or multi-component composite catalyst. When the catalyst is a binary or multi-component composite catalyst, the catalyst concentration is controlled at 0.5 to 3%.

[0024] The following takes the preparation of ethylene carbonate (EC) by cycloaddition of CO2 and ethylene oxide (EO) as an example, focusing on the unit composition and connection relationship of the above-mentioned device, and introducing the conditions and methods for synthesizing cyclic ethylene carbonate using the device.

[0025] The reaction temperature in the bubbling bed reactor of step (a) is 0.05-10wt% at 100-150°C, and the content of ethylene oxide is, for example, 100, 110, 120, 130, 140 and 150°C, but is not limited only to the numerical values ​​listed, and other unlisted numerical values ​​in the numerical range are equally applicable; the pressure is 2.0-4.0MPa, for example, 2.0MPa, 2.2MPa, 2.5MPa, 2.7MPa, 3.0MPa, 3.5MPa and 4.0MPa, but is not limited only to the numerical values ​​listed, and other unlisted numerical values ​​in the numerical range are equally applicable; the residence time is 2-30min, for example, 2min, 5min, 10min, 15min, 20min, 25min and 30min, but is not limited only to the numerical values ​​listed, and other unlisted numerical values ​​in the numerical range are equally applicable.

[0026] The raw material CO2 and ethylene oxide are respectively introduced by the bottom air inlet and the middle liquid inlet of the bubbling bed reactor, and the bottom air inlet is connected to the gas distributor in the bubbling bed reactor. The raw material CO2 is introduced into the bubbling bed reactor through the gas distributor, and the ethylene oxide feed of the middle liquid inlet undergoes a cycloaddition reaction to generate cyclic ethylene carbonate under the action of the filled catalyst, and releases a large amount of heat. Under the action of the reaction heat, the material in the bubbling bed reactor is heated and heated, and the temperature of the bubbling bed reactor is controlled by the circulating feed flow and temperature of the upper liquid inlet of the bubbling bed reactor. The ethylene carbonate solution heated by absorbing the reaction heat is extracted at the bottom liquid outlet of the reactor, and enters the microchannel reactor after being pressurized by the mechanical pump to further deepen the reaction and realize the removal of the reaction heat.

[0027] In order to achieve the withdrawal of the bubbling bed reaction temperature and reaction heat, the temperature of the microchannel reactor and the temperature of the bubbling bed reactor are controlled to have a certain temperature difference, wherein the reaction temperature in the microchannel reactor in step (b) is 80°C to 120°C, for example, 80°C, 85°C, 90°C, 100°C, 110°C and 120°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable; the pressure of the microchannel reactor is controlled at 0.5 to 2.0 MPa, for example, 0.5 MPa, 0.8 MPa, 1.0 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa and 2.0 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable; the residence time of the microchannel reactor is 10s-10min, for example, 10s, 30s, 1min, 2min, 3min, 5min, 8min and 10min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0028] In order to control the bed temperature of the bubbling bed reactor, the material after deep reaction in the microchannel reactor is pressurized by a mechanical pump and further cooled by a cooler, and then circulated back to the bubbling bed reactor, wherein the proportion of the feed circulated to the upper part of the bubbling bed reactor in the step (c) is 70% to 90%, preferably 90%; the remaining part is used as a crude cyclic ethylene carbonate product, still containing a small amount of dissolved CO2 and catalyst, and then enters a catalyst separation unit through a pipeline for further separation and recovery, and the proportion of the material entering the catalyst separation unit is controlled to be 10% to 30%, preferably 10%.

[0029] The catalyst separation unit comprises a flash tank and an evaporator connected in series, the evaporator comprises at least one heater, and the heaters of the evaporator are two connected in series or in parallel. To ensure the separation efficiency of the product and the catalyst, the evaporator is preferably two connected in parallel. At the same time, to ensure the heat integration efficiency, the heaters in each evaporator are at least two connected in series, one of which is connected to the compressor of the heat integration unit and the microchannel reactor of the reaction unit, and the other heater is heated by steam or heat transfer oil. To ensure the heat exchange integration efficiency, the heater in the evaporator mainly supplies the vaporization energy required for the separation of the catalyst and the cyclic ethylene carbonate; under the heat supply of the heater, the vaporization rate of the evaporator is controlled to be 50% to 90%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% and 90%, but it is not limited to the listed values, and other values ​​not listed in this numerical range are also applicable.

[0030] After the connection and control of the above-mentioned reaction units, the reaction heat of CO2 in the process of synthesizing ethylene carbonate by cycloaddition is transferred to the heat exchange medium in the cold material channel of the microchannel reactor, and the heat exchange medium is then separated by gas and liquid and pressurized by the compressor to heat the heater of the evaporator. To ensure the efficiency and effect of heat integration, the heat exchange medium in step (d) is at least one of lithium bromide aqueous solution, ammonia solution, fluorocarbon, and ammonium carbamate solution, for example, it can be 45% to 55% lithium bromide aqueous solution, 20% to 30% ammonia solution, or a combination of one or two of R245fa, R365mfc, R1233zd (E), and R365mfc fluorocarbon, or it can also be a reaction medium of ammonium carbamate. Since the reaction temperature of CO2 cycloaddition is relatively low, in order to ensure the reaction heat integration efficiency, the heat exchange medium is preferably one of the binary mixed fluorocarbons, for example, it can be a combination of R245fa and R365mfc, R1233zd (E) and R365mfc.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention utilizes a microchannel reactor integrated with a bubbling bed reactor, which can further enhance the depth of the cycloaddition reaction while ensuring production efficiency, thereby significantly reducing the reaction residence time, reducing the equipment volume, and improving the production efficiency of the cyclic carbonate device;

[0033] (2) The present invention integrates a microchannel reactor with a heat pump system to efficiently recover and improve the quality of the reaction heat during the reaction of CO2 and alkylene oxide, further improving the system integration, achieving efficient transfer and conversion of cycloaddition reaction heat, greatly improving the preparation efficiency and energy utilization level, and reducing the energy consumption level of the device. When the conversion rate of alkylene oxide exceeds 99%, the energy consumption level of cyclic carbonate preparation can be reduced by at least 50%;

[0034] (3) By adopting the scheme of coupling a bubbling bed reactor with a microchannel reactor, the traditional inefficient second-stage deepening reactor was replaced, ensuring high-throughput and efficient preparation of synthetic cyclic carbonates, which is suitable for large-scale production of 10,000 tons and 100,000 tons, and promoting the application of microchannels in the manufacturing of bulk chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the unit connection of the microchannel carbonate synthesis device according to an embodiment of the present invention;

[0036] Among them, 1-bubbling bed reactor, 2-microchannel reactor, 3-gas-liquid separation tank, 4-compressor, 5-flash tank, 6-evaporator, S1~S11 are material pipelines, and U1~U7 are heat exchange medium pipelines.

[0037] Figure 2 This is a connection diagram of the process system for preparing cyclic carbonate in the traditional industry provided in Comparative Example 1;

[0038] Among them, 1-a first-stage bubbling bed reactor, 2-a second-stage bubbling bed reactor, 3-a cooler, 4-an evaporator, 5A / 5B-a gas-liquid separation tank, and S1-S13 are material pipelines.

[0039] Figure 3 This is a diagram comparing the energy consumption of Examples 5 to 7 and Comparative Example 2. DETAILED DESCRIPTION

[0040] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0041] The specific implementation of the present invention provides a microchannel heat-integrated device for preparing cyclic carbonate reactions. The device includes a reaction unit, a heat-integrated unit, a catalyst separation unit and its attached unit devices connected to each other. The reaction unit is a bubbling bed reactor and a microchannel reactor connected in series, wherein the microchannel reactor is any one of a plate type, a tubular type and a spiral structure, and the microchannel reactor is provided with a hot material channel and a cold material channel, and the hot material channel and the cold material channel are respectively provided with a liquid inlet and a liquid outlet. The catalyst separation unit includes a flash tank and an evaporator connected in series, and at least one heater for vaporization is provided in the evaporator, and the liquid inlet of the flash tank is connected to the hot material channel liquid outlet of the microchannel reactor through a pipeline, and the liquid outlet of the evaporator is connected to the liquid inlet of the bubbling bed reactor through a pipeline. The heat integration unit comprises a gas-liquid separation tank and at least one compressor connected to each other, wherein the liquid inlet of the gas-liquid separation tank is connected to the liquid outlet of the cold material channel of the microchannel reactor, the gas outlet of the compressor is connected to the heater in the evaporator through a pipeline, and the liquid outlet of the heater is connected to the liquid inlet of the cold material channel of the microchannel reactor through a pipeline.

[0042] Implementation case 1:

[0043] This embodiment includes a reaction unit, a heat integration unit, a catalyst separation unit and their attached device systems connected to each other. Among them:

[0044] The reaction unit is a bubbling bed reactor and a microchannel reactor connected in series, wherein the bubbling bed reactor is provided with two liquid inlets, the upper liquid inlet is connected to the hot material channel liquid outlet of the microchannel reaction through a pipeline; the lower part is provided with an air inlet connected to the gas distributor in the bubbling bed reactor, and the gas distributor is installed at a height of 0.3m from the bottom liquid outlet; the bottom is provided with a liquid outlet, which is connected to the tube-side liquid inlet of the microchannel reactor through a pipeline; the microchannel reactor is a stainless steel spiral jacket shell-and-tube type, the hot material channel is a smooth round tube with an equivalent diameter of 15mm, and the cold material channel is a 19mm sleeve. At the same time, in order to facilitate the transfer and transportation of materials, a mechanical pump is provided between the bottom liquid outlet of the bubbling bed reactor and the hot material channel liquid inlet of the microchannel reactor, and the material is pressurized by the mechanical pump and then passed through the hot material channel liquid inlet of the microchannel reactor, and after the microchannel reactor continues to deepen the reaction, it enters the catalyst separation unit to separate the product from the catalyst.

[0045] The catalyst separation unit comprises a flash tank and an evaporator connected in series, wherein the liquid outlet of the microchannel hot material channel is connected to the liquid inlet of the flash tank through a pipeline, and a mechanical pump is arranged on the connecting pipeline; to ensure the separation efficiency, two heaters in series are arranged in the evaporator, wherein the liquid inlet and outlet of one heater are respectively connected to the gas outlet of the heat integration unit and the liquid inlet of the cold material channel of the microchannel reactor through a pipeline, and is the main place for utilizing the reaction heat; the other heater is heated by steam or heat transfer oil as a standby, and is used as an external heat compensation source during the start-up process of the device and when the reaction fluctuates, so as to ensure the normal operation of the evaporator.

[0046] The thermal integration unit comprises a gas-liquid separation tank and a compressor, wherein the gas outlet of the thermal integration unit is the gas outlet of the compressor, and the liquid inlet of the gas-liquid separation tank is connected to the liquid outlet of the cold material channel of the microchannel reactor through a pipeline.

[0047] In order to control the bed temperature of the bubbling bed reactor to be stable, the outlet of the hot material channel of the microchannel reactor is connected to the upper liquid inlet of the bubbling bed reactor through a pipeline, and a mechanical pump and a cooler are arranged on the connecting pipeline. At the same time, in order to ensure the recycling of the catalyst, the outlet of the evaporator is connected to the liquid inlet in the middle of the bubbling bed reactor through a pipeline.

[0048] Comparative Example 1:

[0049] This comparative example provides a conventional two-stage bubbling bed synthesis cyclic carbonate device, the device and its connection relationship of the system are as follows: Figure 2 As shown, the only difference from Example 1 is that: there is no reaction heat integration unit; the reactor in the system is a traditional two bubbling bed reactors connected in series, and an external circulation cooler is arranged outside the first-stage bubbling bed reactor, and the reaction temperature is controlled by the discharge temperature cycle of the external circulation cooling; the positions and methods of inlet and outlet are different, specifically, the liquid inlet of the first-stage bubbling bed reactor is located at the bottom of the reactor, and the liquid outlet is located at the top of the reactor; the top discharge of the first-stage bubbling bed reactor is separated and then enters the second-stage bubbling bed reactor respectively.

[0050] Implementation case 2:

[0051] What is different from Example 1 is that the microchannel reactor in this device is a stainless steel shell-and-tube microchannel reactor, in which the inner diameter of a single tube is 19 mm; the catalyst separation unit is a flash tank and an evaporator, in which a heater is arranged in the evaporator, and the inlet and outlet of the heater are respectively connected to the compressor outlet of the heat integration unit and the liquid inlet of the cold material channel of the microchannel reactor through pipelines; to ensure the heat integration efficiency of the reaction, the heat integration unit includes three gas-liquid separation tanks and three compressors arranged at intervals, and the outlet of the heat integration unit is the outlet of the last compressor.

[0052] Implementation case three:

[0053] What is different from Example 2 is that the microchannel reactor in this device is two groups of 10-layer silicon carbide plate and shell reactors connected in series, wherein the single-layer main channel is a heart-shaped structure with an inner diameter of 3 mm, which is mainly used as a circulation channel for hot materials, and the plate and frame interlayer is used as a cold material channel, which mainly passes heat exchange working fluid for reaction and heat exchange integrated temperature control; the catalyst separation unit is a flash tank and two parallel evaporators, each evaporator is equipped with a heater, and the inlet and outlet of one heater are respectively connected to the compressor outlet of the heat integration unit and the liquid inlet of the cold material channel of the microchannel reactor through pipelines; to meet the heat integration efficiency, the heat integration unit includes two compressors in series, and the outlet of the heat integration unit is the outlet of the last compressor.

[0054] Implementation Case 4:

[0055] What is different from Example 3 is that the microchannel reactor in this device is two groups of 50-layer stainless steel plate shell reactors connected in series, in which the single-layer main channel is a toothed structure with an inner diameter of 50um; the catalyst separation unit is a flash tank and two parallel evaporators, and two heaters are arranged in each evaporator, wherein the inlet and outlet of each heater are respectively connected to the compressor outlet of the heat integration unit and the liquid inlet of the cold material channel of the microchannel reactor through a pipeline; to meet the heat integration efficiency, the heat integration unit includes two parallel compressors, and the outlet of the heat integration unit is the outlet of the last compressor.

[0056] Implementation Case 5:

[0057] This embodiment uses the first embodiment to provide a microchannel heat integrated device for preparing cyclic carbonate reaction, which includes a bubbling bed reactor 1, a microchannel reactor 2, a gas-liquid separation tank 3, a compressor 4, a flash tank 5 and an evaporator 6 connected in sequence.

[0058] The treatment method includes a cycloaddition reaction process, a catalyst separation process, and a heat exchange integration process. The process flow chart is as follows: Figure 1 As shown, the specific steps include:

[0059] (1) 1100 kg / h of raw material CO2 and 1000 kg / h of ethylene oxide are introduced into the bubbling bed reactor 1 through the bottom gas inlet and the upper liquid inlet, respectively, and a cycloaddition reaction occurs under the action of 10.2 wt % of 1-methyl-3-ethylimidazolium bromide ion liquid catalyst, and the pressure of the bubbling bed reactor is controlled at 2.5 MPa, and the residence time is 25 min;

[0060] (2) 11986 kg / h of liquid phase material of 0.4% alkylene oxide and 3.2% dissolved CO2 which have not reacted completely at the bottom of bubbling bed reactor 1 is discharged, and after being pressurized to 2.6 MPa by a mechanical pump, is introduced into microchannel reactor 2 for further cycloaddition reaction, wherein the temperature of microchannel reactor 2 is controlled at 100° C., the pressure is at 2.4 MPa, and the residence time is 5 min.

[0061] (3) The liquid phase after passing through the microchannel reactor 2 contains 2.8% CO2 and 94% ethylene carbonate. In order to control the temperature stability of the bubbling bed reactor 1, 80% of the crude EC product (8390 kg / h) is pressurized by a mechanical pump, cooled to 60°C by a cooler, and then sent to the upper liquid inlet of the bubbling bed reactor 1 for recycling; the remaining 20% ​​of the crude EC (3596 kg / h) is pressurized by the mechanical pump and sent to the catalyst separation unit; wherein the cooling medium of the cooler is 40°C hot water, and the temperature of the bubbling bed reactor 1 is maintained at 169°C by controlling the flow of hot water;

[0062] (4) To realize the integrated utilization of reaction heat, a 74°C heat exchange medium, a 3 / 7 mixed working medium liquid (fluorocarbon) of 1,1,1,3,3-pentafluorobutane and 1-chloro-3,3,3-trifluoropropene, is introduced into the cold material channel of the microchannel reactor 2, and the flow rate of the heat exchange medium is controlled to be 30500 kg / h to realize the stable control of the reaction temperature of the microchannel reactor 2. After heat exchange, 95% of the fluorocarbon is vaporized, and then after passing through the gas-liquid separation tank 3, the liquid phase returns to the microchannel reactor 2, and after the gas phase is compressed to 2.4 MPa by the compressor 4, the gas phase is heated to 150°C and sent to the evaporator 6 for use in the heater of the reboiler, and the liquid phase is separated and recycled back to the microchannel reactor 2 for continued heat exchange.

[0063] (5) To achieve the removal of dissolved CO2, the solution from the microchannel reactor 2 first enters the flash tank 5, and the liquid phase after flash separation is sent to the evaporator 6 to separate the EC product and the catalyst. Under the action of the heat exchange medium mixed with fluorocarbons, the evaporator achieves a 60% vaporization rate, and the remaining 1495 kg / h of 7.3% catalyst solution is pressurized by a pump and circulated to the liquid inlet in the middle of the bubbling bed reactor 1, mixed with fresh ethylene oxide feed, and then enters the bubbling bed reactor 1 for continued use.

[0064] In this embodiment, the conversion rate of ethylene oxide reaches 99.997%, and a total of 414kW of reaction heat is removed. After compression work, 732kW of 150°C heat can be supplied to the outside, while the evaporator heater only needs 504kW of heat, and the heat energy is still 31% surplus, and the reaction heat supply is 100%. After deducting the power consumption of the compressor, the unit product energy consumption is -4.8kW / ton of ethylene carbonate, achieving the goal of efficient utilization of conversion efficiency and reaction heat. The logistics data table of this embodiment is shown in Table 1.

[0065] Implementation Case 6:

[0066] This embodiment provides a microchannel heat integrated device for preparing cyclic carbonate reaction by using the second embodiment, the device comprises a bubbling bed reactor 1, a microchannel reactor 2, a gas-liquid separation tank 3, a primary compressor 4A, a secondary compressor 4B, a tertiary compressor 4C, a flash tank 5 and an evaporator 6 connected in sequence, and specifically comprises the following steps:

[0067] (1) 1100 kg / h of raw material CO2 and 1000 kg / h of ethylene oxide are introduced into the bubbling bed reactor 1 through the bottom gas inlet and the upper liquid inlet, respectively, and a cycloaddition reaction occurs under the action of 0.75 wt % tetrabutylphosphonium bromide ionic liquid and ZnBr2 binary composite catalyst, and the hot spot temperature in the bubbling bed reactor is controlled at 136° C., the pressure is controlled at 3.0 MPa, and the residence time is 30 min;

[0068] (2) 17687 kg / h of liquid phase material of 0.3% alkylene oxide and 3.1% dissolved CO2 that have not reacted completely at the bottom of the bubbling bed reactor 1 is sent to the microchannel reactor 2 through a pipeline for further cycloaddition reaction, wherein the temperature of the microchannel reactor 2 is controlled at 90° C., the pressure is 1.0 MPa, and the residence time is 5 min.

[0069] (3) The liquid phase after passing through the microchannel reactor 2 contains 2.8% CO2 and 97% ethylene carbonate. In order to control the temperature stability of the bubbling bed reactor 1, 80% of the crude EC product, 14149 kg / h, is pressurized by a mechanical pump, cooled to 60°C by a cooler, and then sent to the upper liquid inlet of the bubbling bed reactor 1 for recycling; the remaining 20% ​​of the crude EC, 3537 kg / h, is pressurized by the mechanical pump and sent to the catalyst separation unit; wherein the cooling medium of the cooler is 30°C hot water, and the temperature of the bubbling bed reactor 1 is maintained at 136°C by controlling the flow of hot water;

[0070] (4) To realize the integrated utilization of reaction heat, a 3 / 7 ratio of 1,1,1,3,3-pentafluoropropane and 1,1,2,2,3-pentafluoropropane binary fluorocarbon solution at a temperature of 70°C is introduced into the cold material channel of the microchannel reactor 2, and the flow rate of the binary fluorocarbon mixed solution is controlled to be 30500 kg / h to realize the stable control of the reaction temperature of the microchannel reactor 2. After heat exchange, 84% of the heat exchange medium is vaporized, and then after passing through the gas-liquid separation tank 3, the liquid phase returns to the microchannel reactor 2, and the gas phase is compressed to 2.4 MPa by the three-stage compressor 4A / 4B / 4C, and then the gas phase is heated to 141°C and sent to the evaporator 6 for use in the heater of the reboiler. The liquid phase is separated and recycled back to the microchannel reactor 2 for continued heat exchange.

[0071] (5) To achieve the removal of dissolved CO2, the solution from the microchannel reactor 2 first enters the flash tank 5, and the liquid phase after flash separation is sent to the evaporator 6 to separate the EC product and the catalyst. Under the action of the heat exchange medium mixed with fluorocarbons, the evaporator achieves a 60% vaporization rate, and the remaining 1437 kg / h of 1.3% catalyst solution is pressurized by a pump and circulated to the liquid inlet in the middle of the bubbling bed reactor 1, mixed with fresh ethylene oxide feed, and then enters the bubbling bed reactor 1 for continued use.

[0072] In this embodiment, the conversion rate of ethylene oxide reaches 99.997%, and a total of 404kW of reaction heat is removed. After compression work, 571kW of 149°C heat can be supplied to the outside, while the evaporator heater only needs 403kW of heat, and the reaction heat supply is 100%. After deducting the power consumption of the compressor, the unit product energy consumption is 77kW / ton of ethylene carbonate, achieving the goal of efficient utilization of conversion efficiency and reaction heat. The logistics data table of this embodiment is shown in Table 2.

[0073] Implementation Case 7:

[0074] This embodiment uses the third embodiment to provide a microchannel heat integrated device for preparing cyclic carbonate reaction, the device includes a bubbling bed reactor 1, a microchannel reactor 2, a gas-liquid separation tank 3, a primary compressor 4A, a secondary compressor 4B, a flash tank 5 and an evaporator 6 connected in sequence, and specifically includes the following steps:

[0075] (1) 1100 kg / h of raw material CO2 and 1000 kg / h of ethylene oxide are introduced into the bubbling bed reactor 1 through the bottom gas inlet and the upper liquid inlet, respectively, and a cycloaddition reaction occurs under the action of 3.6 wt % of tetrabutylphosphonium bromide ionic liquid catalyst, and the hot spot temperature in the bubbling bed reactor is controlled at 125° C., the pressure is controlled at 3.0 MPa, and the residence time is 20 min;

[0076] (2) 26529 kg / h of liquid phase discharge of 0.3% alkylene oxide and 4.1% dissolved CO2 at the bottom of the bubbling bed reactor 1 are sent to the microchannel reactor 2 through the pressure control valve for further cycloaddition reaction, wherein the temperature of the microchannel reactor 2 is controlled at 80°C, the pressure is 1.0 MPa, and the residence time is 10 min.

[0077] (3) The liquid phase after passing through the microchannel reactor 2 contains 3.8% CO2 and 94.8% ethylene carbonate. In order to control the temperature stability of the bubbling bed reactor 1, 90% of the crude EC product, 23876 kg / h, is pressurized by a mechanical pump and cooled to 80°C by a cooler and then sent to the upper liquid inlet of the bubbling bed reactor 1 for recycling; the remaining 10% of the crude EC, 2653 kg / h, is pressurized by the mechanical pump and sent to the catalyst separation unit; wherein the cooling medium of the cooler is 60°C hot water, and the temperature of the bubbling bed reactor 1 is maintained at 125°C by controlling the flow of hot water;

[0078] (4) To realize the integrated utilization of reaction heat, a 3 / 7 ratio binary fluorocarbon solution of 1,1,1,3,3-pentafluorobutane and 1-chloro-3,3,3-trifluoropropene at 70°C is introduced into the cold material channel of the microchannel reactor 2, and the flow rate of the binary fluorocarbon mixed solution is controlled to be 85500 kg / h to realize the stable control of the reaction temperature of the microchannel reactor 2. After heat exchange, 62% of the heat exchange medium is vaporized, and after passing through the gas-liquid separation tank 3, the liquid phase returns to the microchannel reactor 2, and the gas phase is compressed to 2.4 MPa by the secondary compressor 4A / 4B, and then the gas phase is heated to 151°C and sent to the evaporator 6 for use by the evaporator heater. The liquid phase is separated and recycled back to the microchannel reactor 2 for continued heat exchange.

[0079] (5) To achieve the removal of dissolved CO2, the solution from the microchannel reactor 2 first enters the flash tank 5, and the liquid phase after flash separation is sent to the evaporator 6 to separate the EC product and the catalyst. Under the action of the heat exchange medium mixed with fluorocarbons, the evaporator achieves a 78% vaporization rate, and the remaining 553 kg / h of 6.5% catalyst solution is pressurized by a pump and circulated to the liquid inlet in the middle of the bubbling bed reactor 1, mixed with fresh ethylene oxide feed, and then enters the bubbling bed reactor 1 for continued use.

[0080] In this embodiment, the conversion rate of ethylene oxide reaches 99.999%, and a total of 567kW of reaction heat is removed. After compression work, 1277kW of 151°C heat can be supplied to the outside, while the evaporator heater only needs 415kW of heat, and the heat energy is still 68% rich, and the reaction heat supply is 100%. After deducting the power consumption of the compressor, the unit product energy consumption is -81.4kW / ton of ethylene carbonate, and the unit product energy consumption reaches the conversion efficiency and the efficient utilization of reaction heat. The logistics data table of this embodiment is shown in Table 3.

[0081] Comparative Example 2:

[0082] The present comparative example provides a method for synthesizing cyclic carbonate using a conventional two-stage bubbling bed device of comparative example 1, which differs from Example 5 only in that: in order to enhance the gas-liquid mass transfer in the two-stage bubbling bed reactor, the gas-liquid ratio of the feed is controlled to 1.8 / 1, the 1-methyl-3-ethylimidazolium bromide ion liquid catalyst is controlled to 10.7wt%, the external circulation cooler adopts 40°C hot water heat exchange cooling, and the temperature of the first stage bubbling bed reactor is controlled to 164°C; the reaction temperature of the second stage bubbling bed reactor is controlled to 120°C, and the residence time is 2 hours; the evaporator adopts steam heating, and the vaporization rate is controlled to 60%, and other operating conditions remain unchanged.

[0083] In this comparative example, after the system runs stably, the final ethylene oxide conversion rate of the first stage bubbling bed reactor is 97%, the ethylene oxide conversion rate of the second stage bubbling bed reactor is 70%, and the total ethylene oxide conversion rate is 99.1%. All the reaction heat is taken out by the 40°C hot water of the external circulation cooler. The evaporator of the catalyst separation section needs to consume an additional 447kW of steam, and the energy consumption is 216.7kW / ton of ethylene carbonate. The logistics data table of this comparative example is shown in Table 4

[0084] From the above embodiments and comparative examples, it can be seen that the present invention adopts a microchannel reactor to replace the external circulation cooler and the second-stage bubbling bed reactor of the traditional first-stage bubbling bed reactor, and utilizes its advantages of efficient heat transfer and mass transfer, which is beneficial to the rapid reaction of ethylene oxide and carbon dioxide, improves the reaction rate, and shortens the reaction residence time; at the same time, by utilizing low-boiling point heat exchange media such as fluorocarbons and lithium bromide aqueous solution, the integrated utilization of reaction heat pump and reaction heat is realized, breaking through the waste of low-temperature reaction heat of CO2 cycloaddition, and realizing the efficient preparation of cyclic vinyl carbonate.

[0085] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

[0086] Table 1 Main flow balance data table of Example 5

[0087]

[0088] Table 2 Main flow balance data table of Example 6

[0089]

[0090] Table 3 Logistics balance data table of Example 7

[0091]

[0092] Table 4 Logistics balance data table of comparative example 2

[0093]

Claims

1. A microchannel heat integrated device for preparing cyclic carbonate reaction, characterized in that: The device comprises a reaction unit, a heat integration unit and a catalyst separation unit connected in sequence, wherein the reaction unit comprises a bubbling bed reactor and a microchannel reactor connected to each other, the microchannel reactor is any one of a plate type, a tube type and a spiral structure, the microchannel reactor is provided with a hot material channel and a cold material channel, and the hot material channel and the cold material channel are each provided with a liquid inlet and a liquid outlet; The heat integration unit comprises a gas-liquid separation tank and at least one compressor connected to each other, wherein the liquid inlet of the gas-liquid separation tank is connected to the liquid outlet of the cold material channel of the microchannel reactor through a pipeline; The catalyst separation unit comprises a flash tank and an evaporator connected in series, the evaporator is provided with at least one heater for catalyst separation, the air inlet of the heater is connected to the air outlet of the compressor through a pipeline, and the liquid outlet of the heater is connected to the liquid inlet of the cold material of the microchannel reactor through a pipeline; The bubbling bed reactor is provided with at least one liquid inlet, an air inlet and a liquid outlet, wherein the liquid outlet of the bubbling bed reactor is connected to the liquid inlet of the hot material channel of the microchannel reactor through a pipeline; the air inlet is connected to the gas distributor in the bubbling bed reactor, and the installation height of the gas distributor is 0.2-1.5m from the liquid outlet.

2. The device according to claim 1, characterized in that Preferably, the bubbling bed reactor is provided with two liquid inlets, namely an upper liquid inlet and a middle liquid inlet, a gas inlet is provided at the lower part, and a liquid outlet is provided at the bottom, the upper liquid inlet is connected to the liquid outlet of the hot material channel of the microchannel reactor through a pipeline, and the middle liquid inlet is connected to the liquid outlet of the evaporator through a pipeline; The equivalent inner diameter of the hot material channel of the microchannel reactor is 10um-19mm.

3. The device according to claim 1, characterized in that The hot material channel liquid outlet of the microchannel reactor is connected to the upper liquid inlet of the bubbling bed reactor and the liquid inlet of the gas-liquid separation tank through pipelines respectively; A mechanical pump and a cooler are arranged on the pipeline connecting the liquid outlet of the hot material channel of the microchannel reactor and the upper liquid inlet of the bubbling bed reactor.

4. The device according to claim 1, characterized in that The evaporator has two heaters connected in series or in parallel, the air inlet of one of them is connected to the compressor outlet of the heat integration unit through a pipeline, and the other heater is heated by steam for standby; In order to ensure the reaction heat integration efficiency, at least two compressors are connected in series.

5. The device according to claim 1, characterized in that A mechanical pump is provided on the connecting pipe between the liquid outlet of the bubbling bed reactor and the liquid inlet of the hot material channel of the microchannel reactor.

6. The device according to claim 1, characterized in that The evaporator comprises a gas outlet and a liquid outlet, and the liquid outlet of the evaporator is connected to the middle liquid inlet of the bubbling bed reactor through a pipeline; A mechanical pump is provided on a pipeline connecting the liquid outlet of the evaporator and the middle liquid inlet of the bubbling bed reactor.

7. A method for realizing heat integration of cyclic carbonate reaction using the device according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: (a) raw materials CO2 and alkylene oxide are introduced into the bubbling bed reactor through the air inlet and the middle liquid inlet respectively, and a cycloaddition reaction occurs under the action of a catalyst; the catalyst is any one of ionic liquid imidazolium bromide, pyridinium bromide, quaternary phosphonium bromide, quaternary ammonium bromide, or a combination of any one of them and any one or more of ZnBr2, CuBr2, NiBr2 and KI metal salt; the feed ratio of CO2 to alkylene oxide is controlled at (1.01-1.5) / 1; (b) the liquid phase discharge of the unreacted alkylene oxide and dissolved CO2 at the bottom of the bubbling bed reactor is pressurized and introduced into the microchannel reactor for further cycloaddition reaction, and the temperature of the microchannel reactor is controlled at 80° C. to 120° C., and the residence time is 10 s to 10 min; (c) After passing through the microchannel reactor, 70% to 90% of the liquid phase is pressurized by a mechanical pump and cooled by a cooler, and then sent to the upper liquid inlet of the bubbling bed reactor for recycling, and the remaining 10% to 30% is pressurized by the mechanical pump and then sent to the catalyst separation unit; wherein the cooler performs heat exchange with a cooling medium at 20 to 40° C., and the temperature of the bubbling bed reactor is controlled by the cooler; (d) In order to realize the integrated utilization of reaction heat, a heat exchange medium at 60 to 80° C. is introduced into the cold material channel of the microchannel reactor, and the reaction temperature of the microchannel reactor is controlled by the flow rate of the heat exchange medium; the heated heat exchange medium is successively sent to the gas-liquid separation tank and the compressor, and then sent to the heater of the evaporator for use; In order to ensure the separation efficiency of the catalyst and the cyclic carbonate product in the evaporator, the vaporization rate of the evaporator is controlled at 50% to 90%.

8. The cyclic carbonate reaction heat integration method according to claim 7, characterized in that: In the step (a), the reaction temperature in the bubbling bed reactor is 100° C. to 150° C., the pressure is 2.0 to 4.0 MPa, and the residence time is 2 to 30 min; the catalyst concentration is 0.5% to 12% of the mass of the feed alkylene oxide.

9. The cyclic carbonate reaction heat integration method according to claim 7, characterized in that: In the step (b), the outlet pressure of the microchannel reactor is between 1.0 and 3.0 MPa; in the step (d), the heat exchange medium is at least one of lithium bromide aqueous solution, ammonia solution, fluorocarbon, and ammonium carbamate solution.

10. The cyclic carbonate reaction heat integration method according to claim 7, characterized in that: In order to ensure the heat exchange integration effect, the heat exchange medium in step (d) is preferably a binary fluorocarbon.

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