System for directly preparing vinyl fluoride

Abstract

The utility model discloses a system for directly preparing vinyl fluoride, which comprises an HF (hydrogen fluoride) storage tank and an acetylene storage tank, the HF storage tank is connected with a first centrifugal pump, the first centrifugal pump is connected with a micro-channel reactor, the micro-channel reactor is provided with a heat supply device, and the acetylene storage tank is connected with a second centrifugal pump. The micro-channel reactor is sequentially connected with the condenser, the falling film absorber, the rectifying tower, the light component and heavy component removal device, the gas storage tank and the filling tank; the acetylene storage tank is connected with the second centrifugal pump, the second centrifugal pump is connected with the purifying and drying device, and the purifying and drying device is connected with the microchannel reactor; the HF storage tank is also connected with one end of the HF recovery device, and the other end of the HF recovery device is connected with the falling film absorber. By using the micro-channel reactor, reactants are fully mixed, the reaction efficiency is high, the volume of the reactor is small, and the investment cost is low; full-automatic and clean process production can be achieved, the labor intensity of operators is low, and the number of needed workers is small.

Description

Technical Field

[0001] The utility model belongs to the field of synthesis of polyvinyl fluoride and other resins. Monofluoroethylene is a raw material for synthesis of polyvinyl fluoride, and specifically relates to a system for directly preparing monofluoroethylene. Background Art

[0002] Vinylidene fluoride (VDF) is an important fluorinated hydrocarbon compound commonly used in the production of polymers such as polyvinylidene fluoride (PVDF), which has widespread applications in the electrical, chemical, and other fields. Currently, the following methods are used to produce VDF: 1. Acetylene hydrofluorination: Vinylidene fluoride is produced by reacting acetylene with hydrogen fluoride gas. This is a relatively common method, but requires strict control of reaction conditions to avoid side reactions. 2. Pyrolysis (Chinese Patents CN114478183A disclose methods for preparing VDF in 143a and 142b; Chinese Patent Publication CN104557446A discloses a method for preparing vinylidene fluoride monomer): Fluorinated hydrocarbons are thermally cracked at high temperatures to produce VDF. This method typically requires high-temperature equipment and an efficient cooling system. 3. Catalytic reaction: A catalyst is used to promote the reaction of ethylene and fluorine gas, thereby improving reaction efficiency and selectivity. Despite the continuous development of production technology, the production of monofluoroethylene still faces some challenges and problems: 1. Safety: Hydrogen fluoride is an extremely corrosive and toxic gas. Improper handling can pose a threat to the environment and personal safety. Therefore, extremely high safety measures are required during the production process. 2. Reaction selectivity: In the fluorination reaction, how to control the reaction conditions to increase the yield of monofluoroethylene and reduce the formation of by-products remains a technical challenge. 3. Cost issues: The cost of fluorination raw materials and equipment is high, which affects the overall production economics. 4. Environmental impact: The handling and discharge of fluorides may have a negative impact on the environment, so more environmentally friendly production equipment needs to be developed.

[0003] Because acetylene and hydrogen fluoride are bulk chemicals with readily available raw materials, and the acetylene hydrofluorination reaction is an electrophilic addition reaction of acetylene, it is simpler and more economical than other methods. Therefore, acetylene hydrofluorination gas-phase synthesis is the preferred method. However, when using a tank reactor for gas-phase reaction, the reactor and heat exchange system are very large and complex, resulting in high energy consumption, large circulation volumes, significant raw material waste, high environmental pollution, high operator labor intensity, and a harsh working environment. Furthermore, these processes are associated with uneven reaction, difficult heat exchange, and low product quality. Utility Model Content

[0004] The utility model proposes a system for directly preparing monofluoroethylene, which uses acetylene hydrofluorination to synthesize monofluoroethylene in the gas phase. The application of a microchannel reactor will effectively solve the problems of uneven gas phase reaction and difficult heat exchange. In addition, HF can be recycled in the process, reducing costs, and providing a feasible solution for the synthesis and large-scale production of monofluoroethylene.

[0005] The technical solution of the present utility model is achieved as follows:

[0006] A system for directly preparing monofluoroethylene, comprising an HF storage tank and an acetylene storage tank, wherein the HF storage tank is connected to a first centrifugal pump, which is connected to a microchannel reactor, wherein a heat supply device is provided on the microchannel reactor, and wherein the microchannel reactor is sequentially connected to a condenser, a falling film absorber, a rectifying tower, a light-heavy degassing device, a gas storage tank, and a filling tank;

[0007] The acetylene storage tank is connected to a second centrifugal pump, the second centrifugal pump is connected to a purification and drying device, and the purification and drying device is connected to a microchannel reactor;

[0008] The HF storage tank is also connected to one end of the HF recovery device, and the other end of the HF recovery device is connected to the falling film absorber.

[0009] The purified and dried acetylene gas reacts with HF in a microchannel reactor, which is then connected to a condenser to cool the gas. The gas then enters a falling film absorber to remove HF. The resulting HF aqueous solution is recycled and then recirculated in an HF storage tank. The product mixed gas enters a distillation tower and a degassing unit to remove impurities such as difluoroethane and trace amounts of acetylene and ethylene, and then enters a gas storage tank to complete the filling of monofluoroethylene.

[0010] Preferably, the microchannel reactor is filled with an aluminum-based catalyst, and the main component of the catalyst may be aluminum trifluoride.

[0011] Preferably, the purification and drying device is filled with potassium dichromate and silica gel to perform preliminary purification and drying treatment on the crude product in the acetylene storage tank.

[0012] Preferably, the microchannel reactor is made of monel or silicon carbide. The microchannel reactor provides a reaction site for HF and acetylene, and heat is supplied by a heating device to maintain the reaction temperature at 250-350°C, maintaining the optimal reaction temperature. The molar feed ratio of HF to acetylene in the microchannel reactor is 1.0-1.2:1, allowing the acetylene to completely react with HF to generate product gas.

[0013] Preferably, the heating device is an electric heater.

[0014] Preferably, the falling film absorber is provided with a feed inlet, a bottom gas outlet, and an upper outlet. The condenser is connected to the feed inlet, the bottom gas outlet is connected to an HF recovery device, and the upper outlet is connected to a distillation column. The falling film absorber can remove most of the HF in the mixed gas, and the HF gas is converted into an aqueous solution and passed through the recovery device to an HF storage tank for secondary use.

[0015] Preferably, the outer wall of the microchannel reactor is provided with a jacket, heat transfer oil is provided in the jacket, a heating wire is provided in the heat transfer oil, and the heating wire is electrically connected to an electric heater.

[0016] Beneficial effects of the utility model:

[0017] The utility model uses a microchannel reactor to fully mix the reactants, has high reaction efficiency, small reactor volume, and low investment cost; can realize fully automatic and clean process production, has low operator labor intensity, and requires fewer personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the implementation scheme of the present invention or the technical solution in the prior art, the following is a brief introduction to the drawings required for the implementation scheme or the description of the prior art.

[0019] Figure 1 This is a system diagram of the present utility model.

[0020] Figure 2 This is a schematic structural diagram of the falling film absorber of the utility model.

[0021] Figure 3 This is a schematic structural diagram of the microchannel reactor of the present utility model.

[0022] Among them, 1-HF storage tank, 2-first centrifugal pump, 3-microchannel reactor, 4-condenser, 5-falling film absorber, 6-acetylene storage tank, 7-second centrifugal pump, 8-purification and drying device, 9-heating device, 10-distillation tower, 11-light and heavy removal device, 12-gas storage tank, 13-filling tank, 14-HF recovery device;

[0023] 31-jacket, 32-heat transfer oil, 33-heating wire. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and examples.

[0025] Example 1

[0026] like Figure 1As shown: A system for directly preparing monofluoroethylene, comprising an HF storage tank 1 and an acetylene storage tank 6, wherein the acetylene storage tank 6 is connected to a second centrifugal pump 7, which is connected to a purification and drying device 8, which is connected to a microchannel reactor 3; the HF storage tank 1 is connected to a first centrifugal pump 2, which is connected to a microchannel reactor 3, wherein the microchannel reactor 3 is filled with an aluminum-based catalyst, and a heating device 9 is provided on the microchannel reactor 3, which is an electric heater; the microchannel reactor 3 is sequentially connected to a condenser 4, a falling film absorber 5, a distillation tower 10, a light and heavy removal device 11, a gas storage tank 12, and a filling tank 13; the HF storage tank 1 is also connected to one end of an HF recovery device 14, and the other end of the HF recovery device 14 is connected to the falling film absorber 5.

[0027] A second centrifugal pump 7 pumps the crude product from the acetylene storage tank 6 into a purification and drying unit 8, where potassium dichromate, silica gel, and other materials are used to perform preliminary purification and drying. The purified and dried acetylene gas reacts with HF in a microchannel reactor 3, where heating is provided by a heating unit 9 at a reaction temperature of 250-350°C. A first centrifugal pump 2 pumps HF from the HF storage tank 1 into the microchannel reactor 3 at a molar feed ratio of HF to acetylene of 1.0-1.2:1, ensuring complete reaction between the acetylene and HF. The gas is then cooled by a condenser 4, which then enters a falling film absorber 5 for HF removal. The resulting HF aqueous solution passes through an HF recovery unit 14 and enters the HF storage tank 1 for secondary use. The product mixed gas in the falling film absorber 5 enters the distillation tower 10 and the de-light and de-heavy device 11 to remove difluoroethane and trace acetylene, ethylene and other impurities contained in the product, obtaining high-purity monofluoroethylene gas, which enters the gas storage tank 12 for storage and waits for the completion of the filling of monofluoroethylene before entering the filling tank 13.

[0028] The microchannel reactor (YMC-165B) 3 used above has a high safety factor, a large heat exchange surface area, and a low process investment cost; it can realize fully automatic and clean process production, has low labor intensity for operators, requires fewer personnel, and HF can be recovered during the process.

[0029] (a) Gaseous hydrogen fluoride and acetylene are introduced into a microchannel reactor 3 for reaction to produce ethylene monofluoride gas; the hydrogen fluoride flow rate is 23-26 g / min, and the acetylene flow rate is 25-27 g / min. During the reaction, the temperature of the microchannel reactor 3 is maintained at 250-350°C by a heating device.

[0030] (b) The mixed gas obtained in step (a) is cooled by a condenser 4 and then treated by a falling film absorber 5, a distillation tower 10 and a degassing device 11 to obtain a high-purity monofluoroethylene product gas. After storage, the gas is filled into a gas tank 13.

[0031] The reactants in the present invention are heated in the microchannel reactor 3, which is heated evenly and has controllable thermal energy, thus achieving the purpose of energy saving; the entire reaction process is in a closed state, is pollution-free, has no material waste, and is safe and reliable.

[0032] Example 2

[0033] like Figure 2 As shown, the falling film absorber 5 is provided with a feed port, a bottom gas outlet and an absorber upper discharge port, the condenser 4 is connected to the feed port, the bottom gas outlet is connected to the HF recovery device 14, and the absorber upper discharge port is connected to the distillation tower 10.

[0034] The cooled gas enters the falling film absorber 5 to remove HF, and the produced HF aqueous solution enters the HF recovery device 14 through the bottom gas outlet, and is finally pumped into the HF storage tank 1 for secondary utilization. The product mixed gas in the falling film absorber 5 enters the distillation tower 10 and the degassing device 11 through the upper discharge port of the absorber to remove difluoroethane and trace acetylene, ethylene and other impurities contained in the product, thereby obtaining high-purity monofluoroethylene gas.

[0035] Example 3

[0036] like Figure 3 As shown, the outer wall of the microchannel reactor 3 is provided with a jacket 31, and heat transfer oil 32 is provided in the jacket 31. A heating wire 33 is provided in the heat transfer oil 32, and the heating wire 33 is electrically connected to an electric heater. The electric heater heats the heating wire 33, and the heating wire 33 heats the heat transfer oil 32 to provide heat to the microchannel reactor 3.

[0037] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A system for directly preparing monofluoroethylene, characterized in that: The invention comprises an HF storage tank (1) and an acetylene storage tank (6), wherein the HF storage tank (1) is connected to a first centrifugal pump (2), the first centrifugal pump (2) is connected to a microchannel reactor (3), the microchannel reactor (3) is provided with a heat supply device (9), and the microchannel reactor (3) is sequentially connected to a condenser (4), a falling film absorber (5), a distillation tower (10), a light and heavy gas removal device (11), a gas storage tank (12), and a filling tank (13); The acetylene storage tank (6) is connected to a second centrifugal pump (7), the second centrifugal pump (7) is connected to a purification and drying device (8), and the purification and drying device (8) is connected to a microchannel reactor (3); The HF storage tank (1) is also connected to one end of an HF recovery device (14), and the other end of the HF recovery device (14) is connected to a falling film absorber (5).

2. A system for directly preparing monofluoroethylene according to claim 1, characterized in that: The microchannel reactor (3) is filled with an aluminum-based catalyst.

3. A system for directly preparing monofluoroethylene according to claim 1, characterized in that: The purification and drying device (8) is filled with potassium dichromate and silica gel.

4. A system for directly preparing monofluoroethylene according to claim 1, characterized in that: The microchannel reactor (3) is made of monel or silicon carbide.

5. A system for directly preparing monofluoroethylene according to claim 1, characterized in that: The heating device (9) is an electric heater.

6. A system for directly preparing monofluoroethylene according to claim 1, characterized in that: The falling film absorber (5) is provided with a feed port, a bottom gas outlet, and an absorber upper discharge port; the condenser (4) is connected to the feed port; the bottom gas outlet is connected to an HF recovery device (14); and the absorber upper discharge port is connected to a distillation tower (10).

7. A system for directly preparing monofluoroethylene according to claim 5, characterized in that: The outer wall of the microchannel reactor (3) is provided with a jacket (31), heat-conducting oil (32) is provided in the jacket (31), a heating wire (33) is provided in the heat-conducting oil (32), and the heating wire (33) is electrically connected to an electric heater.

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