An apparatus and method for synthesizing vinyl chloride using acetylene.

Abstract

This invention belongs to the field of vinyl chloride synthesis, and specifically discloses an apparatus and method for synthesizing vinyl chloride using an acetylene process. The apparatus includes a mixing unit, a preheating unit, a reaction unit, a first demister, a condensation unit, and a second demister arranged sequentially along the flow direction of the reactant gases; as well as a shell-and-tube heat exchange unit and a liquid catalyst supply unit. A first tube box is provided between the tube inlet of the shell-and-tube heat exchange unit and the outlet of the reaction unit, and a second tube box is provided between the tube outlet of the shell-and-tube heat exchange unit and the inlet of the reaction unit, forming a circulation loop. The first and second tube boxes are respectively connected to the output and recovery pipelines of the catalyst supply unit, which are connected to a storage tank. A steam drum unit is provided between the inlet and outlet of the shell side of the shell-and-tube heat exchange unit. This apparatus can achieve gas-liquid self-circulation reaction, requires no additional power equipment, and can produce high-quality steam as a byproduct, offering advantages such as energy saving, emission reduction, and good economic efficiency.

Description

Technical Field

[0001] This invention relates to the field of vinyl chloride synthesis technology, and more particularly to an apparatus and method for synthesizing vinyl chloride using an acetylene method. Background Technology

[0002] Polyvinyl chloride (PVC) is an important synthetic plastic, and its production, which consumes large amounts of chlorine, has driven the development of the chlor-alkali industry. The synthesis of vinyl chloride, a key technology in PVC production, currently mainly includes the acetylene process, the conventional ethylene chlorination process, and the balanced oxychlorination process. Among these, the acetylene process, based on the coal chemical route, is the mainstream method for synthesizing vinyl chloride in my country. However, the mercuric chloride catalyst used in this method causes serious environmental pollution. Although the loss and emission of mercury can be reduced by lowering the mercury content in the catalyst and strengthening mercury fixation, the mercury pollution problem cannot be fundamentally solved, thus severely limiting its sustainable and healthy development. Therefore, it is necessary to develop mercury-free catalysts to address the mercury pollution problem.

[0003] Currently, the synthesis of vinyl chloride from acetylene generally employs a gas-solid phase reaction method, and various mercury-free gas-solid phase catalysts have been developed, such as noble metal and non-noble metal series mercury-free catalysts. While noble metal catalysts exhibit high catalytic activity, they suffer from high costs, while non-noble metal catalysts, although inexpensive and economical, suffer from significant loss of active components. Furthermore, the gas-solid phase reaction method also faces challenges such as difficulty in removing reaction heat, surface runaway, localized hot spots, and catalyst carbon buildup.

[0004] In light of this, the research on mercury-free liquid-phase catalysts has become an important branch of innovation, and liquid-phase mercury-free catalysts for the hydrochlorination of acetylene have been developed. For example, Qin Gaofei et al. prepared a mercury-free liquid-phase catalyst for vinyl chloride synthesis using PtCl4 as the main active component, primary amine JM-T as the solvent, and dodecane as the diluent. Yu Zhiyong used one or more combinations of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluorophosphate as ionic liquid supports, and gold, palladium, platinum, tin, copper, or rhodium as active components for catalyzing the hydrochlorination of acetylene. However, existing gas-liquid phase vinyl chloride production equipment requires heat sources, cold sources, and power equipment to regulate the temperature of the liquid catalyst during the liquid catalyst circulation, which not only increases equipment and thermal energy costs but also results in a significant waste of reaction heat. More importantly, the temperature of the liquid catalyst changes dynamically and continuously as the reaction proceeds. Long-term operation will increase the workload of the heat exchanger, ultimately reducing the temperature control effect on the liquid catalyst. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and method for synthesizing vinyl chloride using the acetylene method, in order to solve the technical problems of high cost, energy waste, and reduced temperature control effect of liquid catalyst in the synthesis of vinyl chloride using existing gas-liquid phase vinyl chloride production equipment.

[0006] The technical solution for achieving the objective of this invention is as follows:

[0007] In a first aspect, embodiments of the present invention provide an apparatus for synthesizing vinyl chloride by acetylene method, comprising a mixing unit, a preheating unit, a reaction unit, a first demister, a condensation unit and a second demister arranged sequentially along the flow direction of the reaction gas; as well as a shell-and-tube heat exchange unit and a liquid catalyst supply unit;

[0008] A first tube box is provided between the tube-side inlet of the shell-and-tube heat exchange unit and the outlet of the reaction unit, and a second tube box is provided between the tube-side outlet of the shell-and-tube heat exchange unit and the inlet of the reaction unit to form a circulation loop. The first tube box has an outlet for connecting to the first demister unit.

[0009] A steam chamber unit is provided between the shell-side inlet and outlet of the shell-side heat exchange unit. The steam chamber unit is used to regulate the temperature of the liquid catalyst used in the reaction.

[0010] The liquid catalyst supply unit includes a storage tank, and an output pipeline and a recovery pipeline connected to the storage tank, wherein the output pipeline is connected to the first pipe box, and the recovery pipeline is connected to the second pipe box; a forced circulation pipeline is provided on the output pipeline and the recovery pipeline, and the forced circulation pipeline connects the output pipeline and the recovery pipeline.

[0011] In conjunction with the first aspect, in a preferred embodiment of the present invention, a gas distributor is provided at the inlet of the reaction unit.

[0012] In conjunction with the first aspect, in another embodiment of the present invention, a gas pressurization unit is further connected in parallel between the mixing unit and the reaction unit, and a control valve is provided on the pipelines at both ends of the gas pressurization unit.

[0013] In conjunction with the first aspect, in a preferred embodiment of the present invention, the liquid catalyst supply unit further includes a catalyst pump;

[0014] The catalyst pump is located on the output pipeline and between the forced circulation pipeline and the first pipe box.

[0015] In conjunction with the first aspect, in a preferred embodiment of the present invention, the liquid catalyst supply unit further includes a preparation tank;

[0016] The preparation tank is located on top of the storage tank for preparing the liquid catalyst for the reaction.

[0017] Secondly, embodiments of the present invention also provide a method for synthesizing vinyl chloride based on the above apparatus, comprising:

[0018] Acetylene and hydrogen chloride gases are mixed in the mixing unit to obtain a mixed gas.

[0019] The mixed gas is preheated to a temperature of 85-100°C and a pressure of 20-40 kPa in the preheating unit, and then transported to the reaction unit to react and generate syngas under the action of a liquid catalyst.

[0020] The synthesis gas is processed sequentially through a first defoaming unit, a condensation unit, and a second defoaming unit to recover and reuse the liquid catalyst and obtain crude vinyl chloride.

[0021] In conjunction with the second aspect, in another embodiment of the present invention, the method for synthesizing vinyl chloride includes:

[0022] Acetylene and hydrogen chloride gases are mixed in the mixing unit to obtain a mixed gas.

[0023] The mixed gas is pressurized to 0.09-0.2 MPa in the gas pressurization unit and then transported to the reaction unit to react and generate syngas under the action of a liquid catalyst.

[0024] The synthesis gas is processed sequentially through a first defoaming unit, a condensation unit, and a second defoaming unit to recover and reuse the liquid catalyst and obtain crude vinyl chloride.

[0025] In conjunction with the second aspect, in a preferred embodiment of the present invention, the liquid catalyst is heated to a temperature of 100–130°C via the shell-and-tube heat exchange unit.

[0026] In conjunction with the second aspect, in a preferred embodiment of the present invention, the temperature at which the mixed gas reacts under the action of the liquid catalyst is 100–240°C.

[0027] In conjunction with the second aspect, in a preferred embodiment of the present invention, the synthesis gas is cooled to below 40°C in the condensation unit.

[0028] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present invention include at least the following:

[0029] The apparatus for synthesizing vinyl chloride using the acetylene method provided in this invention includes a shell-and-tube heat exchange unit and a liquid catalyst supply unit, as well as a mixing unit, a preheating unit, a reaction unit, a first demister unit, a condensation unit, and a second demister unit arranged sequentially along the flow direction of the reaction gas. A first tube box is installed between the tube-side inlet of the shell-and-tube heat exchange unit and the outlet of the reaction unit, and a second tube box is installed between the tube-side outlet of the shell-and-tube heat exchange unit and the inlet of the reaction unit, forming a circulation loop. An outlet connecting the first demister unit is opened in the first tube box. Simultaneously, a storage tank and an output pipeline and a recovery pipeline connected to the storage tank are provided in the liquid catalyst supply unit. The output pipeline and the recovery pipeline are respectively connected to the first tube box and the second tube box, and a forced circulation pipeline connecting the output pipeline and the recovery pipeline is provided. A steam bath unit for adjusting the temperature of the liquid catalyst for the reaction is installed between the shell-side inlet and outlet of the shell-and-tube heat exchange unit. Before the device is started, the liquid catalyst in the liquid catalyst supply unit is preheated and then delivered to the first tube box. The liquid catalyst in the first tube box is then heated to the required reaction temperature by passing through the tube side of the shell-and-tube heat exchange unit, thus realizing the temperature control of the liquid catalyst. After the device is in normal operation, the liquid catalyst supply unit is cut off so that the heated liquid catalyst enters the second tube box to contact the preheated raw material mixture and enters the reaction unit to produce synthesis gas through gas-liquid reaction. Thus, by taking advantage of the difference in gas content between the reaction unit and the shell-and-tube heat exchange unit, a self-circulating reaction is realized between the reaction unit, the first tube box, the shell-and-tube heat exchange unit, and the second tube box. In view of this, the first aspect of the present invention utilizes the cooperation between a shell-and-tube heat exchange unit and a steam drum unit to regulate the reaction temperature, facilitating temperature control and achieving good mass and heat transfer, effectively solving the problem of localized overheating within the reaction unit. Secondly, the reaction heat generated in the self-circulating reaction can be rapidly transferred to the steam drum unit for the production of high-quality steam when passing through the shell-and-tube heat exchange unit, thereby realizing the recovery and utilization of reaction heat and effectively solving the problem of increased heat exchanger load caused by continuously rising reaction temperature, exhibiting good economic efficiency. Furthermore, the pressure of the steam drum unit can be controlled to precisely regulate the shell-and-tube heat exchange unit. The hot water temperature is controlled in a flexible and simple manner, eliminating the need for external heat sources and power equipment, thus saving energy, reducing emissions, and promoting low carbon emissions and environmental protection. Thirdly, the self-circulating reaction of the gas and liquid phases allows the catalytically active components to dissolve in a homogeneous liquid system, avoiding carbon buildup on the surface of the gas-solid phase catalyst and catalyst pulverization caused by the pressure of the reacting gas or friction between particles. Fourthly, the syngas generated from the reaction passes through the first demisting unit, the condensation unit, and the second demisting unit sequentially, allowing the liquid catalyst entrained in the gas phase to be separated and recycled, reducing the consumption of liquid catalyst and demonstrating good economic efficiency.

[0030] The method for synthesizing vinyl chloride provided in this invention involves mixing acetylene and hydrogen chloride gases to obtain a mixed gas, preheating it to a temperature of 85–100°C and a pressure of 20–40 kPa, and then reacting it under the action of a liquid catalyst to generate synthesis gas. The synthesis gas is then sequentially passed through a first demisting unit to separate and recover the liquid catalyst, a condensation unit for cooling, and a second demisting unit to separate and recover the liquid catalyst again, yielding crude vinyl chloride. Therefore, the vinyl chloride synthesis method provided in this invention ensures that the reaction achieves a qualified acetylene conversion rate by heating the liquid catalyst before the reaction and controlling its temperature during the reaction to maintain the catalytic reaction under optimal temperature conditions. Furthermore, the use of a gas-liquid phase reaction and the ability to use a mercury-free liquid catalyst solves the mercury pollution problem in existing vinyl chloride production. Additionally, the liquid catalyst in the circulating reaction can be replenished and replaced online without stopping the production line, significantly improving production efficiency. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the apparatus for synthesizing vinyl chloride by acetylene method provided in an embodiment of the present invention.

[0033] Reference numerals: 1-Mixing unit; 2-Preheating unit; 3-Reaction unit; 4-First demister unit; 5-Condensation unit; 6-Second demister unit; 7-Shell-tube heat exchanger unit; 8-Liquid catalyst supply unit; 9-Steam unit; 10-First tube box; 11-Second tube box; 12-Gas pressurization unit; 31-Gas distributor; 81-Storage tank; 82-Output pipeline; 83-Recovery pipeline; 84-Forced circulation pipeline; 85-Catalyst pump; 86-Preparation tank; 91-Steam-water mixer; (C1; C2; C3)-Control valve. Detailed Implementation

[0034] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments without creative effort are within the scope of protection of the present invention.

[0035] In the following description of embodiments of the present invention, the terms "front," "rear," "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "installed," "connected," and "linked," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0036] To address the high cost, energy waste, and reduced temperature control effectiveness of liquid catalysts in the synthesis of vinyl chloride using existing gas-liquid phase vinyl chloride production equipment, this invention provides an apparatus and method for synthesizing vinyl chloride via an acetylene process. Specifically, Figure 1 This is a schematic diagram of the apparatus for synthesizing vinyl chloride by acetylene method provided in an embodiment of the present invention.

[0037] according to Figure 1 As shown, the apparatus for synthesizing vinyl chloride using the acetylene method includes a mixing unit 1, a preheating unit 2, a reaction unit 3, a first demister unit 4, a condensation unit 5, and a second demister unit 6 arranged sequentially along the flow direction of the reaction gases; a shell-and-tube heat exchange unit 7; and a liquid catalyst supply unit 8. A first tube box 10 is provided between the tube-side inlet of the shell-and-tube heat exchange unit 7 and the outlet of the reaction unit 3, and a second tube box 11 is provided between the tube-side outlet of the shell-and-tube heat exchange unit 7 and the inlet of the reaction unit 3 to form a circulation loop. The first tube box 10 has an outlet for connecting to the first demister unit 4. A steam bath unit 9 is provided between the shell-side inlet and shell-side outlet of the shell-and-tube heat exchange unit 7, and the steam bath unit 9 is used to regulate the temperature of the liquid catalyst used in the reaction. The liquid catalyst supply unit 8 includes a storage tank 81, and an output pipeline 82 and a recovery pipeline 83 connected to the storage tank 81. The output pipeline 82 is connected to a first pipe box 10, and the recovery pipeline 83 is connected to a second pipe box 11. A forced circulation pipeline 84 is provided on the output pipeline 82 and the recovery pipeline 83, and the forced circulation pipeline 84 conducts the output pipeline 82 and the recovery pipeline 83.

[0038] The apparatus for synthesizing vinyl chloride by acetylene method provided in this embodiment includes a shell-and-tube heat exchange unit 7 and a liquid catalyst supply unit 8, as well as a mixing unit 1, a preheating unit 2, a reaction unit 3, a first defoaming unit 4, a condensing unit 5 and a second defoaming unit 6 arranged sequentially along the flow direction of the reaction gas. The system comprises a first tube box 10 located between the tube inlet of the shell-and-tube heat exchange unit 7 and the outlet of the reaction unit 3, and a second tube box 11 located between the tube outlet of the shell-and-tube heat exchange unit 7 and the inlet of the reaction unit 3, forming a circulation loop. An outlet for the first demister unit 4 is opened in the first tube box 10. Simultaneously, a storage tank 81 and an output pipeline 82 and a recovery pipeline 83 connected to the storage tank 81 are provided in the liquid catalyst supply unit 8. The output pipeline 82 and the recovery pipeline 83 are respectively connected to the first tube box 10 and the second tube box 11. A forced circulation pipeline 84 is provided on the output pipeline 82 and the recovery pipeline 83 to conduct the output pipeline 82 and the recovery pipeline 83. A steam package unit 9 for adjusting the temperature of the liquid catalyst for the reaction is provided between the shell inlet and the shell outlet of the shell-and-tube heat exchange unit 7. Before the device is started, the liquid catalyst in the liquid catalyst supply unit 8 is preheated and then delivered to the first tube box 10. The liquid catalyst in the first tube box 10 is then heated to the required temperature for the reaction by passing through the tube side of the shell-and-tube heat exchange unit 7, thus realizing the temperature control of the liquid catalyst. After the device is in normal operation, the liquid catalyst supply unit 8 is cut off so that the heated liquid catalyst enters the second tube box 11 to contact the preheated raw material mixture and enters the reaction unit 3 to produce synthesis gas through gas-liquid reaction. Thus, by taking advantage of the difference in gas content between the reaction unit 3 and the shell-and-tube heat exchange unit 7, a self-circulating reaction is realized between the reaction unit 3, the first tube box 10, the shell-and-tube heat exchange unit 7, and the second tube box 11.In view of this, in the first aspect, the shell-and-tube heat exchange unit 7 and the steam drum unit 9 work together to regulate the reaction temperature, which facilitates the control of the reaction temperature and provides good mass and heat transfer, effectively solving the problem of local overheating in the reaction unit 3. In the second aspect, the reaction heat generated in the self-circulating reaction can be quickly transferred to the steam drum unit 9 for the production of high-quality steam when passing through the shell-and-tube heat exchange unit 7, thereby realizing the recovery and utilization of reaction heat and effectively solving the problem of increased heat exchanger load caused by continuous increase in reaction temperature, which has good economic benefits. At the same time, the pressure of the steam drum unit 9 can be controlled to precisely control the shell-and-tube heat exchange unit 7. The hot water temperature control method is flexible and simple, and no external heat source or power equipment is required, which is energy-saving, emission-reducing, low-carbon and environmentally friendly. Thirdly, the self-circulating reaction of the gas and liquid phases allows the catalytic active components to dissolve in a homogeneous liquid phase system, thereby avoiding carbon accumulation on the surface of the gas-solid phase catalyst and pulverization of the catalyst due to the influence of the reaction gas pressure or friction between particles. Fourthly, the synthesis gas generated by the reaction passes through the first demisting unit 4, the condensation unit 5 and the second demisting unit 6 in sequence, thereby separating and recycling the liquid catalyst entrained in the gas phase, reducing the consumption of liquid catalyst and having good economic benefits.

[0039] In this embodiment of the invention, the mixing unit 1 is a device capable of mixing the raw material gases hydrogen chloride and acetylene, such as a pipeline mixer or a gas mixer. Of course, those skilled in the art should understand that this embodiment of the invention does not impose any particular limitation on the specific model of the pipeline mixer, gas mixer, or other equipment selected, as long as it can achieve a uniform mixing of hydrogen chloride and acetylene.

[0040] In this embodiment of the invention, the preheating unit 2 is a device capable of heating the mixed gas, such as a gas preheater or a shell-and-tube heat exchanger. Of course, those skilled in the art should understand that this embodiment of the invention does not impose any particular limitation on the specific model of the gas preheater, shell-and-tube heat exchanger, or other equipment selected, as long as it can heat the hydrogen chloride and acetylene mixture to the required temperature.

[0041] In this embodiment of the invention, the reaction unit 3 is a device for gas-liquid reaction between the mixed gas and the liquid catalyst, such as a reactor or reaction tower capable of gas-liquid reaction. Of course, those skilled in the art should understand that this embodiment of the invention does not impose any particular limitation on the specific model of the reactor, reaction tower, or other equipment selected, as long as it can ensure sufficient and uniform contact and reaction between the mixed gas and the liquid catalyst.

[0042] In this embodiment of the invention, the shell-and-tube heat exchange unit 7 is a device used to regulate the temperature of the liquid catalyst to maintain a constant reaction temperature. Specifically, during initial operation, steam enters the shell-side hot water side of the shell-and-tube heat exchange unit 7 via a steam-water mixer 91 to heat the liquid catalyst in the tube side to the required reaction temperature. After the device is running normally, the circulating liquid catalyst rapidly transfers the heat of reaction generated by the shell-and-tube heat exchange unit 7 to the steam drum unit 9 to produce high-quality steam as a byproduct. Simultaneously, the steam drum level is stabilized by replenishing pure water. Therefore, this embodiment of the invention achieves self-circulating temperature control through the cooperation of the shell-and-tube heat exchange unit 7 and the steam drum unit 9, thereby ensuring the normal progress of the gas-liquid reaction and maintaining a high acetylene conversion rate.

[0043] In this embodiment of the invention, the first demisting unit 4 and the second demisting unit 6 are devices capable of separating the liquid catalyst from the synthesis gas, such as demisters. Of course, those skilled in the art should understand that this embodiment of the invention does not particularly limit the specific model of the demister used, as long as it can effectively separate the liquid catalyst entrained in the synthesized vinyl chloride gas.

[0044] In this embodiment of the invention, the condensing unit 5 is a device capable of cooling the synthesized vinyl chloride gas to a suitable temperature. For example, it can be a tube-type heat exchanger, or other cooling equipment. It should be noted that in this embodiment of the invention, the synthesized vinyl chloride gas treated by the first defoaming unit 4 is cooled to a temperature below 40°C in the condensing unit 5.

[0045] It should be noted that, in this embodiment of the invention, the tube-side outlet of the shell-and-tube heat exchange unit 7 is also connected to the tube-side liquid phase outlet of the condensation unit 5 and the liquid phase outlet of the second demister unit 6, so as to reuse the liquid catalyst entrained in the gas phase.

[0046] In this embodiment of the invention, the liquid catalyst supply unit 8 is a device for supplying and recovering liquid catalyst to the reaction unit 3. Figure 1As shown in the example, the liquid catalyst supply unit 8 includes a storage tank 81, and an output pipeline 82 and a recovery pipeline 83 connected to the storage tank 81. The output pipeline 82 is connected to the first pipe box 10, and the recovery pipeline 83 is connected to the second pipe box 11. A forced circulation pipeline 84 is provided on the output pipeline 82 and the recovery pipeline 83. The forced circulation pipeline 84 conducts the output pipeline 82 and the recovery pipeline 83. At the same time, a catalyst pump 85 is also provided on the output pipeline 82 between the storage tank 81 and the first pipe box 10. A preparation tank 86 is also provided on the top of the storage tank 81. When the device is initially running, the liquid catalyst is prepared in the preparation tank 86 and added to the storage tank 81, where it is heated to 65–100°C. Then, the control valve C1 on the output line 82 is opened, and the control valve C2 on the recovery line 83 and the control valve C3 on the forced circulation line 84 are closed. The liquid catalyst is then pumped to the first tube box 10 by the catalyst pump 85. The liquid catalyst in the first tube box 10 is then heated to 100–130°C through the tube side of the tube-side heat exchange unit 7. After the device is running normally, the control valves C1 on the output line 82, C2 on the recovery line 83, and C3 on the forced circulation line 84 are shut off, allowing the liquid catalyst to undergo a self-circulation reaction. When the activity of the liquid catalyst decreases, the control valve C2 on the recovery pipeline 83 is opened to release part of the liquid catalyst in the second tube box 11 into the storage tank 81, and the deactivated liquid catalyst in the storage tank 81 is drained for recovery; at the same time, in accordance with the feeding steps of the initial operation, an appropriate amount of new liquid catalyst is added into the circulating reaction in a reasonable proportion to ensure that the reaction reaches the qualified acetylene conversion rate.

[0047] It should be noted that the operation mode of the liquid catalyst supply unit 8 in this embodiment of the invention includes: during initial operation, after the liquid catalyst has been delivered to the first tube box 10, a forced circulation mode can be implemented between the catalyst pump 85, the first tube box 10, the tube-type heat exchange unit 7, the second tube box 11, and the forced circulation pipeline 84. Meanwhile, the control valve C1 on the output pipeline 82 and the control valve C2 on the recovery pipeline 83 are in the closed state, and the control valve C3 on the forced circulation pipeline 84 is in the open state. This allows the liquid catalyst to be quickly heated to the required reaction temperature using external power equipment.

[0048] In this embodiment of the invention, a gas distributor 31 is also provided at the inlet of the reaction unit 3 so that the particle size of the preheated or pressurized mixed gas is distributed between 10-1000um, thereby improving the contact effect between the mixed gas and the liquid catalyst and improving the reaction efficiency.

[0049] In this embodiment of the invention, a gas pressurization unit 12 is connected in parallel between the mixing unit 1 and the reaction unit 3, and control valves are provided on the pipelines at both ends of the gas pressurization unit 12, so that the mixed gas can be pressurized and then sent to the reaction unit 3 for gas-liquid phase reaction, which is convenient for control.

[0050] It should be noted that the liquid catalyst described in the embodiments of the present invention is preferably a mercury-free liquid-phase catalyst, such as a mercury-free liquid-phase catalyst prepared with PtCl4 as the main active component, primary amine JM-T as the solvent, and dodecane as the diluent; or a mercury-free liquid-phase catalyst using one or more combinations of 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, and 1-ethyl-3-methylimidazolium hexafluorophosphate as the ionic liquid support, and gold, palladium, platinum, tin, copper, or rhodium as the active component. In this embodiment, the specific components and sources of the mercury-free liquid-phase catalyst are not particularly limited, as long as it can catalyze the synthesis of vinyl chloride from acetylene.

[0051] Based on the above description, the working principle and process of the acetylene-based vinyl chloride synthesis apparatus provided in this embodiment of the invention are as follows:

[0052] The raw materials, hydrogen chloride and acetylene gas, are mixed in mixing unit 1 and then preheated in preheating unit 2. The preheated mixture enters reaction unit 3 and reacts under the action of a liquid catalyst to generate syngas. After the reaction, the syngas passes through first demisting unit 4 for initial separation and recovery of entrained liquid catalyst, condensation unit 5 for cooling to a reasonable output temperature, and second demisting unit 6 for further separation and recovery of residual liquid catalyst before exiting the device. The tube-side outlet of shell-and-tube heat exchange unit 7 can be connected to the tube-side liquid phase outlet of condensation unit 5 and the liquid phase outlet of second demisting unit 6 to send the separated and recovered liquid catalyst into the self-circulating reaction. Firstly, during initial operation, the liquid catalyst in storage tank 81 is heated and sent to first tube box 10, then flows through the tube side of shell-and-tube heat exchange unit 7 and is heated to the required reaction temperature before contacting the preheated mixture for a gas-liquid reaction. After normal operation, control valve C1 on output line 82, control valve C2 on recovery line 83, and control valve C3 on forced circulation line 84 are simultaneously shut off to allow the liquid catalyst to circulate and react. When the activity of the liquid catalyst decreases, the control valve C2 on the recovery pipeline 83 is opened, and part of the liquid catalyst in the second tube box 11 is placed into the storage tank 81. Then, the deactivated liquid catalyst in the storage tank 81 is drained and ready for recovery. At the same time, according to the feeding steps during initial operation, an appropriate amount of new liquid catalyst is added into the circulating reaction in a reasonable proportion to ensure that the reaction reaches a qualified acetylene conversion rate. Secondly, during the initial operation of the unit, steam enters the shell-side hot water side of the shell-and-tube heat exchange unit 7 through the steam-water mixer 91 to heat the liquid catalyst in the tube side to the temperature required for the reaction. After the unit is in normal operation, the circulating liquid catalyst quickly transfers the heat of reaction generated when passing through the shell-and-tube heat exchange unit 7 to the steam bunker unit 9 for the production of high-quality steam. At the same time, the liquid level in the steam bunker is stabilized by supplementing with pure water.

[0053] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0054] Example 1

[0055] The raw materials, hydrogen chloride and acetylene gas (molar ratio of 1.05 to 1.1:1), are mixed in mixing unit 1 and then heated in preheating unit 2 to a temperature of 85 to 100°C and a pressure of 20 to 40 kPa. The mixture is then sent to reaction unit 3 where it reacts under the action of a liquid catalyst to generate syngas. The reaction temperature is 100 to 240°C. The syngas then passes through a first demisting unit 4 to initially separate and recover the liquid catalyst entrained in the syngas. The mixture is then cooled to a temperature of ≤40°C in condensation unit 5. Finally, the mixture passes through a second demisting unit 6 to further separate and recover the residual liquid catalyst before exiting the unit to obtain crude vinyl chloride. During initial operation, the liquid catalyst in storage tank 81 is heated to 65-100°C by jacketed steam. Then, control valve C1 on output pipeline 82 is opened to deliver the heated liquid catalyst to the first tube box 10. After flowing through the tube side of shell-and-tube heat exchange unit 7, it is heated to 100-130°C before entering the second tube box 11 to react with the preheated mixed gas. After normal operation, control valve C1 on output pipeline 82, control valve C2 on recovery pipeline 83, and control valve C3 on forced circulation pipeline 84 are shut off to allow the liquid catalyst to circulate. When the activity of the liquid catalyst decreases, control valve C2 on recovery pipeline 83 is opened to transfer a portion of the liquid catalyst from the second tube box 11 to storage tank 81. The deactivated liquid catalyst in storage tank 81 is then drained for recovery. Simultaneously, following the initial feeding procedure, an appropriate amount of new liquid catalyst is added to the circulating reaction in a reasonable proportion to ensure that the reaction achieves a qualified acetylene conversion rate. Meanwhile, during the initial operation of the device, steam enters the shell-side hot water side of the shell-and-tube heat exchange unit 7 via the steam-water mixer 91 to heat the liquid catalyst in the tube side to 100-130°C. After the device is in normal operation, the circulating liquid catalyst quickly transfers the heat of reaction generated by the shell-and-tube heat exchange unit 7 to the steam package unit 9 to produce high-quality steam as a byproduct. At the same time, the liquid level in the steam package is stabilized by supplementing pure water.

[0056] Example 2

[0057] The raw materials hydrogen chloride and acetylene gas (molar ratio of 1.05 to 1.1:1) are mixed in mixing unit 1 and then pressurized to 0.09 to 0.2 MPa in gas pressurization unit 12. They are then transported to reaction unit 3, where they react under the action of a liquid catalyst to generate synthesis gas. The reaction temperature is 100 to 240°C. The synthesis gas after the reaction is first separated and the liquid catalyst entrained in the synthesis gas is recovered in the first demisting unit 4. The condensing unit 5 cools the gas to a temperature of ≤40°C. Finally, the remaining liquid catalyst in the synthesis gas is separated and recovered in the second demisting unit 6 before exiting the device to obtain crude vinyl chloride. During initial operation, the liquid catalyst in storage tank 81 is heated to 65-100°C by jacketed steam. Then, control valve C1 on output pipeline 82 is opened to deliver the heated liquid catalyst to the first tube box 10. It then flows through the tube side of shell-and-tube heat exchange unit 7, where it is heated to 100-130°C before entering the second tube box 11 to react with the preheated mixed gas. After normal operation, control valve C1 on output pipeline 82, control valve C2 on recovery pipeline 83, and control valve C3 on forced circulation pipeline 84 are shut off to allow the liquid catalyst to circulate. When the activity of the liquid catalyst decreases, control valve C2 on recovery pipeline 83 is opened, releasing some of the liquid catalyst from the second tube box 11 into storage tank 81. The deactivated liquid catalyst in storage tank 81 is then drained for recovery. Simultaneously, following the initial feeding procedure, an appropriate amount of new liquid catalyst is added to the circulating reaction in a reasonable proportion to ensure a satisfactory acetylene conversion rate. Meanwhile, during the initial operation of the device, steam enters the shell-side hot water side of the shell-and-tube heat exchange unit 7 via the steam-water mixer 91 to heat the liquid catalyst in the tube side to 100-130°C. After the device is in normal operation, the circulating liquid catalyst quickly transfers the heat of reaction generated by the shell-and-tube heat exchange unit 7 to the steam package unit 9 to produce high-quality steam as a byproduct. At the same time, the liquid level in the steam package is stabilized by supplementing pure water.

[0058] For those skilled in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances. The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. An apparatus for synthesizing vinyl chloride using an acetylene process, characterized in that, It includes a mixing unit, a preheating unit, a reaction unit, a first demister, a condensation unit, and a second demister arranged sequentially along the flow direction of the reactant gas; as well as a shell-and-tube heat exchange unit and a liquid catalyst supply unit; A first tube box is provided between the tube-side inlet of the shell-and-tube heat exchange unit and the outlet of the reaction unit, and a second tube box is provided between the tube-side outlet of the shell-and-tube heat exchange unit and the inlet of the reaction unit to form a circulation loop. The first tube box has an outlet for connecting to the first demister unit. A gas distributor is provided at the inlet of the reaction unit; A steam chamber unit is provided between the shell-side inlet and outlet of the shell-side heat exchange unit. The steam chamber unit is used to regulate the temperature of the liquid catalyst used in the reaction. The liquid catalyst supply unit includes a storage tank and an output pipeline and a recovery pipeline connected to the storage tank, wherein the output pipeline is connected to the first pipe box and the recovery pipeline is connected to the second pipe box; a forced circulation pipeline is provided on the output pipeline and the recovery pipeline, and the forced circulation pipeline connects the output pipeline and the recovery pipeline; The liquid catalyst supply unit further includes a catalyst pump; the catalyst pump is located on the output pipeline and between the forced circulation pipeline and the first pipe box.

2. The apparatus for synthesizing vinyl chloride by acetylene method according to claim 1, characterized in that, A gas pressurization unit is connected in parallel between the mixing unit and the reaction unit, and control valves are provided on the pipelines at both ends of the gas pressurization unit.

3. The apparatus for synthesizing vinyl chloride by acetylene method according to claim 1, characterized in that, The liquid catalyst supply unit also includes a preparation tank; The preparation tank is located on top of the storage tank for preparing the liquid catalyst for the reaction.

4. A method for synthesizing vinyl chloride, characterized in that, The apparatus for synthesizing vinyl chloride using the acetylene method as described in any one of claims 1 or 3. Specifically, it includes: Acetylene and hydrogen chloride gases are mixed in the mixing unit to obtain a mixed gas. The mixed gas is preheated to a temperature of 85-100°C and a pressure of 20-40 kPa in the preheating unit, and then transported to the reaction unit to react and generate syngas under the action of a liquid catalyst. Before the steam package unit is started, the liquid catalyst in the liquid catalyst supply unit is preheated and then transported to the first tube box. The liquid catalyst in the first tube box is then heated to the required temperature for the reaction by passing through the tube side of the shell-and-tube heat exchange unit, thus realizing the temperature control of the liquid catalyst. After the device is in normal operation, the liquid catalyst supply unit is cut off so that the heated liquid catalyst enters the second tube box to contact the preheated raw material mixture and enters the reaction unit to produce synthesis gas through gas-liquid reaction. Thus, by taking advantage of the difference in gas content between the reaction unit and the shell-and-tube heat exchange unit, a self-circulating reaction is realized between the reaction unit, the first tube box, the shell-and-tube heat exchange unit, and the second tube box. The synthesis gas is processed sequentially through a first defoaming unit, a condensation unit, and a second defoaming unit to recover and reuse the liquid catalyst and obtain crude vinyl chloride.

5. The method for synthesizing vinyl chloride according to claim 4, characterized in that, The liquid catalyst is heated to a temperature of 100–130°C by the shell-and-tube heat exchange unit.

6. The method for synthesizing vinyl chloride according to claim 5, characterized in that, The temperature at which the mixed gas reacts under the action of the liquid catalyst is 100–240°C.

7. The method for synthesizing vinyl chloride according to claim 6, characterized in that, The synthesis gas is cooled to below 40°C in the condensation unit.

8. A method for synthesizing vinyl chloride, characterized in that, The apparatus for synthesizing vinyl chloride using the acetylene method according to claim 2 specifically includes: Acetylene and hydrogen chloride gases are mixed in the mixing unit to obtain a mixed gas. The mixed gas is pressurized to 0.09-0.2 MPa in the gas pressurization unit and then transported to the reaction unit to react and generate syngas under the action of a liquid catalyst. Before the steam unit is started, the liquid catalyst in the liquid catalyst supply unit is preheated and then transported to the first tube box. The liquid catalyst in the first tube box is then heated to the required reaction temperature by passing through the tube side of the shell-and-tube heat exchange unit, thus realizing the temperature control of the liquid catalyst. After the device is in normal operation, the liquid catalyst supply unit is cut off so that the heated liquid catalyst enters the second tube box to contact the preheated raw material mixture and enters the reaction unit to produce synthesis gas through gas-liquid reaction. Thus, by taking advantage of the difference in gas content between the reaction unit and the shell-and-tube heat exchange unit, a self-circulating reaction is realized between the reaction unit, the first tube box, the shell-and-tube heat exchange unit, and the second tube box. The synthesis gas is processed sequentially through a first defoaming unit, a condensation unit, and a second defoaming unit to recover and reuse the liquid catalyst and obtain crude vinyl chloride.

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