Reformer outlet gas treatment system and method

Abstract

The application provides a converter outlet mixed gas treatment system and method. The converter outlet mixed gas treatment system comprises a converter outlet pipeline, a condensing separation device and a vaporization device, two ends of the converter outlet pipeline are connected with an outlet of a converter and an inlet of a purification device respectively, a first end of the condensing separation device and a first end of the vaporization device are connected with the converter outlet pipeline, a second end of the condensing separation device is connected with a second end of the vaporization device, the first end of the condensing separation device and the first end of the vaporization device are located between the outlet of the converter and the inlet of the purification device, and a third end of the condensing separation device is connected with an inlet of the converter through a pipeline.

Description

Technical Field

[0001] This invention relates to the field of polyvinyl chloride production technology using the calcium carbide method, and more particularly to a converter outlet mixed gas treatment system and method. Background Technology

[0002] In the calcium carbide process for producing polyvinyl chloride (PVC), acetylene and hydrogen chloride gases, or acetylene, hydrogen chloride, and vinyl chloride gases, enter the converter. Within the converter's tubes, acetylene and hydrogen chloride react under catalysis to produce vinyl chloride. The acetylene content at the outlet of the first converter must be ≤30%, and the acetylene content at the outlet of the second converter must be ≤3%. The acetylene, hydrogen chloride, and vinyl chloride gases from the second converter pass through a mercury separator, a crude vinyl chloride cooler, a combined foam deacidification tower, a water washing tower (optional), an alkali washing tower, compression, crude vinyl chloride molecular sieve drying (optional), and distillation. The vinyl chloride purity reaches 99.9%, and the resulting product is then sent to the polymerization unit to produce PVC powder.

[0003] In the distillation process, the total condenser (generally cooled by 7°C water) condenses most of the vinyl chloride. The uncondensed vinyl chloride gas, along with acetylene, hydrogen, nitrogen, methane, and oxygen, enters the tail gas condenser (generally cooled by -26 to -35°C chilled water), where some vinyl chloride is condensed again. The uncondensed vinyl chloride gas, along with acetylene, hydrogen, nitrogen, methane, and oxygen from the tail gas condenser, enters the tail gas adsorption unit. The separated nitrogen, methane, oxygen, and a small amount of hydrogen are released into the atmosphere. The separated hydrogen goes to the hydrogen chloride synthesis unit to react with chlorine to produce hydrogen chloride. The separated acetylene and vinyl chloride gas go to the converter, where they react again to produce vinyl chloride.

[0004] As vinyl chloride in the distillation unit continuously condenses, the pipeline from the tail gas condenser outlet to the tail gas adsorption unit contains highly concentrated acetylene, hydrogen, methane, and oxygen. Since acetylene can spontaneously decompose under high pressure and concentration, and acetylene with oxygen, hydrogen with oxygen, and methane with oxygen can also explode when their concentrations reach certain levels, the acetylene content at the outlet of the downstream converter must be ≤3%.

[0005] 1. An acetylene content >3% at the outlet of the post-conversion unit will affect the safe operation of the distillation unit; currently, there are no production units or processes adapted to an acetylene content >3% at the outlet of the post-conversion unit.

[0006] 2. In some cases, in order to keep the acetylene content at the outlet of the downstream conversion ≤3%, production costs and maintenance expenses will increase significantly (e.g., short catalyst lifespan, large number of scrapped catalysts to be replaced with new ones; frequent overturning and pumping of the incubator, etc.). Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a converter outlet mixed gas treatment system and method to address the shortcomings of the prior art.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A converter outlet mixed gas treatment system, comprising: a converter outlet pipeline, a condensation separation device, and an evaporation device, wherein the two ends of the converter outlet pipeline are respectively connected to the outlet of the converter and the inlet of the purification device; the first end of the condensation separation device and the first end of the evaporation device are both connected to the converter outlet pipeline; the second end of the condensation separation device is connected to the second end of the evaporation device; the first end of the condensation separation device and the first end of the evaporation device are both located between the outlet of the converter and the inlet of the purification device; and the third end of the condensation separation device is connected to the inlet of the converter through a pipeline.

[0009] The beneficial effects of adopting the technical solution of this invention are as follows: Gas with an acetylene content >3% at the outlet of the downstream conversion unit is divided into two streams. One stream undergoes condensation and separation to separate acetylene and hydrogen chloride before entering the converter for further conversion. The condensed vinyl chloride is then evaporated and mixed with the other stream of gas, resulting in an acetylene content <3%, thus reducing the acetylene content in the gas before it enters subsequent units, allowing for safe production. The invention also fully considers the utilization of cold and heat, reducing the increased consumption of cooling capacity. Furthermore, it reduces the acetylene content in the gas going to the purification, compression, and distillation units, preventing the risk of explosion due to high acetylene content in the gas from the compression and distillation units. Finally, it meets the safety production requirements of an acetylene content >3% at the outlet of the downstream conversion unit.

[0010] Furthermore, the condensation separation device includes: a first cooler, a liquid vinyl chloride tank, a condenser, and a first heater. The converter outlet pipe is connected to the first cooler via a pipe. The first cooler is connected to the liquid vinyl chloride tank and the condenser via pipes. The condenser is connected to the liquid vinyl chloride tank and the first heater via pipes. The first heater is connected to the converter inlet via a pipe.

[0011] The beneficial effects of adopting the above-mentioned further technical solution are as follows: The gas going to the condensation separation device is cooled by the first cooler. The condensate from the first cooler enters the liquid vinyl chloride tank. The gas cooled by the first cooler enters the condenser, where some of the gas (vinyl chloride, high-boiling substances) is condensed. The condensate from the condenser enters the liquid vinyl chloride tank. The uncondensed gas is heated by the heater, and the heated gas goes to the pre-converter stage. The gas going to the pre-converter stage is converted by the converter, forming a mixture with another gas stream. The gas going to the condensation separation device is cooled by the cooler and then enters the condenser again, where most of the vinyl chloride is condensed. The condensate enters the liquid vinyl chloride tank. The uncondensed gases, such as acetylene, hydrogen chloride, and vinyl chloride, are heated by the heater and participate in the reaction again before going to the pre-converter stage.

[0012] Furthermore, the evaporation device includes a first evaporator, the liquid vinyl chloride tank is connected to the first evaporator via a pipeline, a pump is installed on the pipeline between the liquid vinyl chloride tank and the first evaporator, and the first evaporator is connected to the converter outlet pipeline via a pipeline.

[0013] The beneficial effects of adopting the above-mentioned further technical solution are as follows: Liquid vinyl chloride from the liquid vinyl chloride tank is pumped into the evaporator, where the vinyl chloride and other gases evaporated from the evaporator mix with another gas stream. The liquid vinyl chloride is pumped back into the evaporator, where the evaporated vinyl chloride is heated by a heater and mixed with the other gas stream. After cooling, the temperature of the mixture is >0°C, and it enters the purification unit (acid removal tower, water washing tower, alkali washing tower). The evaporator exchanges heat with circulating chilled water (containing calcium chloride or ethylene glycol), which is then cooled and sent to a cooler to cool the gas entering the condensation and separation unit. This reduces the acetylene content while maximizing the utilization of heat and cold; the equipment in the device is minimal; and the cooling energy released by the re-evaporation of the condensed vinyl chloride is precisely used to cool the gas.

[0014] Furthermore, a second cooler is installed on the converter outlet pipe, and the first evaporator is connected to the second cooler and the purification device via a pipeline; the second cooler is connected to the liquid vinyl chloride tank via a pipeline.

[0015] The beneficial effect of adopting the above-mentioned further technical solution is that the second cooler is used to cool another gas stream. The other gas stream passes through the second cooler, and the cooled gas mixes with vinyl chloride and other gases evaporated from the evaporator to form a mixed gas. After mixing, the temperature is >0°C, and the mixture enters the purification device. The condensate from the second cooler enters the liquid vinyl chloride tank.

[0016] Furthermore, the first evaporator is connected to a circulating chilled water pump via a pipeline, the circulating chilled water pump is connected to a circulating chilled water tank via a pipeline, the first evaporator is connected to the first cooler and the second cooler via pipelines, and the circulating chilled water tank is connected to the first cooler and the second cooler via pipelines.

[0017] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the water in the circulating chilled water tank (containing calcium chloride or ethylene glycol) is pumped out by the circulating chilled water pump, enters the evaporator through pipelines, and the circulating chilled water pipeline exiting the evaporator splits into two branches. One branch enters the first cooler, and the third circulating chilled water pipeline exiting the first cooler returns to the circulating chilled water tank (containing calcium chloride or ethylene glycol). The other branch enters the cooler, and the fourth circulating chilled water pipeline exiting the cooler returns to the circulating chilled water tank. This reduces the acetylene content while maximizing the utilization of heat and cold; the equipment in the device is less numerous; and the cooling energy released by the re-evaporation of condensed vinyl chloride is just enough to cool the gas.

[0018] Furthermore, the pump is connected to the first evaporator and the second evaporator respectively. The first evaporator is connected to the second heater through two pipes. The second heater is connected to the converter outlet pipe through a pipe. The second evaporator is connected to the second heater through a pipe.

[0019] The beneficial effects of adopting the above-mentioned further technical solution are that, due to the large amount of condensed vinyl chloride, some of the liquid vinyl chloride needs to be heated and evaporated with hot water (or steam), requiring the addition of an evaporator. The acetylene content entering the purification unit (deacidification tower, water washing tower, alkali washing tower) is very low, and the compression and distillation units operate safely and reliably. Liquid vinyl chloride from the tank is pumped out and divided into two streams. One stream of liquid vinyl chloride enters the first evaporator. The vinyl chloride and other gases evaporated in the first evaporator enter the heater for heating. The liquid entrained in the gas entering the heater also enters the first evaporator, where the heated gas mixes with the other gas stream. The liquid vinyl chloride from the tank is pumped out, and the other stream of liquid vinyl chloride enters the second evaporator. The vinyl chloride and other gases evaporated in the second evaporator enter the heater for heating, where the heated gas mixes with the other gas stream. The evaporator exchanges heat with circulating chilled water (containing calcium chloride or ethylene glycol). The circulating chilled water is cooled and then sent to a cooler to cool the gas entering the condensation and separation unit.

[0020] Furthermore, the first heater is provided with a hot water inlet and a hot water outlet; the condenser is provided with a deep chilled water inlet and a deep chilled water outlet; the liquid vinyl chloride tank is connected to a high-boiling-point treatment device via a pipeline; and the second heater is provided with a hot water inlet and a hot water outlet.

[0021] The beneficial effects of adopting the above-mentioned further technical solution are that the hot water for the heater can be from the conversion unit or from an external device. This facilitates selection and installation according to actual needs, improving applicability. The deep chilled water for the condenser comes from an external device. High-boiling-point substances in the liquid vinyl chloride tank are sent to the high-boiling-point substance treatment unit via a second pipeline.

[0022] Furthermore, the second evaporator is provided with a hot water inlet and a hot water outlet.

[0023] The beneficial effect of adopting the above-mentioned further technical solution is that the second evaporator exchanges heat through circulating hot water. That is, the evaporation of the evaporator is heated by the hot water.

[0024] Furthermore, the circulating chilled water pump is connected to a distillation unit via a pipeline, the distillation unit is connected to the second evaporator via a pipeline, and the second evaporator is connected to the circulating chilled water tank via a pipeline.

[0025] The beneficial effects of adopting the above-mentioned further technical solution are that, due to the large amount of vinyl chloride condensed, the large amount of cold energy released by the evaporation of vinyl chloride can be used for the cold energy required by the total condenser and the finished product condenser of the distillation unit, thus making great use of the cold energy released by the evaporator. The acetylene content entering the purification unit (deacid removal tower, water washing tower, alkali washing tower) is very low, and the operation of the compression and distillation unit is safe and reliable; the acetylene content is greatly reduced while maximizing the utilization of heat and cold. The evaporator absorbs heat during evaporation to cool the circulating chilled water, which then goes to the distillation unit (total condenser, finished product condenser) to condense vinyl chloride into a liquid state, making full use of the cold energy of evaporation. The circulating chilled water in the circulating chilled water tank (containing calcium chloride or ethylene glycol) is pumped by another pipeline to the total condenser and the finished product condenser of the distillation unit to condense vinyl chloride. After heat exchange with the total condenser and the finished product condenser, the return water pipeline goes into the evaporator, and the pipeline exiting the evaporator returns to the circulating chilled water tank.

[0026] Furthermore, the present invention also provides a method for treating mixed gas at the outlet of a converter, based on a system for treating mixed gas at the outlet of a converter. The method includes: S1, gas enters the converter outlet pipeline through the outlet of the converter; wherein the gas includes acetylene, hydrogen chloride, and vinyl chloride; S2, the gas is divided into two streams in the converter outlet pipeline, one stream of gas enters a condensation and separation device; S3, after the gas is treated by the condensation and separation device, the uncondensed gas re-enters the converter for conversion; the condensed gas is mixed with the other stream of gas.

[0027] The beneficial effects of adopting the technical solution of this invention are as follows: Gas with an acetylene content >3% at the outlet of the downstream conversion unit is divided into two streams. One stream undergoes condensation and separation to separate acetylene and hydrogen chloride before entering the converter for further conversion. The condensed vinyl chloride is then evaporated and mixed with the other stream of gas, resulting in an acetylene content <3%, thus reducing the acetylene content in the gas before it enters subsequent units, allowing for safe production. The invention also fully considers the utilization of cold and heat, reducing the increased consumption of cooling capacity. Furthermore, it reduces the acetylene content in the gas going to the purification, compression, and distillation units, preventing the risk of explosion due to high acetylene content in the gas from the compression and distillation units. Finally, it meets the safety production requirements of an acetylene content >3% at the outlet of the downstream conversion unit.

[0028] The advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is one of the structural schematic diagrams of the converter outlet mixed gas treatment system provided in an embodiment of the present invention.

[0031] Figure 2 This is a second schematic diagram of the structure of the converter outlet mixed gas treatment system provided in an embodiment of the present invention.

[0032] Figure 3 The third schematic diagram of the converter outlet mixed gas treatment system provided in the embodiment of the present invention.

[0033] Explanation of reference numerals in the attached diagram: 1. Converter outlet pipeline; 2. First cooler; 3. Liquid vinyl chloride tank; 4. Condenser; 5. First heater; 6. First evaporator; 7. Pump; 8. Second cooler; 9. Circulating chilled water pump; 10. Circulating chilled water tank; 11. Second evaporator; 12. Second heater; 13. Distillation unit. Detailed Implementation

[0034] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and 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, and therefore should not be construed as a limitation of the present invention.

[0039] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0040] like Figures 1 to 3 As shown in the figure, an embodiment of the present invention provides a converter outlet mixed gas treatment system, including: a converter outlet pipeline 1, a condensation separation device, and an evaporation device. The two ends of the converter outlet pipeline 1 are respectively connected to the outlet of the converter and the inlet of the purification device. The first end of the condensation separation device and the first end of the evaporation device are both connected to the converter outlet pipeline 1. The second end of the condensation separation device is connected to the second end of the evaporation device. The first end of the condensation separation device and the first end of the evaporation device are both located between the outlet of the converter and the inlet of the purification device. The third end of the condensation separation device is connected to the inlet of the converter through a pipeline.

[0041] The beneficial effects of adopting the technical solution of this invention are as follows: Gas with an acetylene content >3% at the outlet of the downstream conversion unit is divided into two streams. One stream undergoes condensation and separation to separate acetylene and hydrogen chloride before entering the converter for further conversion. The condensed vinyl chloride is then evaporated and mixed with the other stream of gas, resulting in an acetylene content <3%, thus reducing the acetylene content in the gas before it enters subsequent units, allowing for safe production. The invention also fully considers the utilization of cold and heat, reducing the increased consumption of cooling capacity. Furthermore, it reduces the acetylene content in the gas going to the purification, compression, and distillation units, preventing the risk of explosion due to high acetylene content in the gas from the compression and distillation units. Finally, it meets the safety production requirements of an acetylene content >3% at the outlet of the downstream conversion unit.

[0042] Figures 1 to 3 The arrows in the diagram can represent the flow trajectory and direction of gas or liquid.

[0043] This invention splits the gas with an acetylene content >3% at the outlet of the downstream converter into two streams. One stream is condensed and separated to separate acetylene and hydrogen chloride, and then enters the converter for further conversion. The condensed vinyl chloride is then evaporated and mixed with the other stream of gas, so that the acetylene content is <3%, and the gas enters the downstream equipment, which can then operate safely.

[0044] If the acetylene content at the outlet of the downstream converter is greater than 3%, it will affect the safety of the distillation unit. To solve this problem, this invention separates the acetylene, hydrogen chloride, vinyl chloride, and other gases from the converter outlet manifold into two streams before entering the purification unit. One stream undergoes condensation and separation to separate the acetylene and hydrogen chloride, which then enters the converter for further conversion. The condensed vinyl chloride is then evaporated and mixed with the other stream. After mixing, the temperature is greater than 0°C, and the mixture enters the subsequent units (a combined foam deacidification tower, water washing tower, alkali washing tower, compression, crude vinyl chloride molecular sieve drying (available in some companies, optional), and distillation unit). In this way, the acetylene content in the gas is less than 3%, allowing the subsequent units to operate safely.

[0045] The condensation of vinyl chloride requires cooling, while its re-evaporation requires heat. This invention fully considers the utilization of both cooling and heating, minimizing the increased consumption of cooling.

[0046] like Figure 1 As shown, the condensation separation device further includes: a first cooler 2, a liquid vinyl chloride tank 3, a condenser 4, and a first heater 5. The converter outlet pipe 1 is connected to the first cooler 2 via a pipe. The first cooler 2 is connected to the liquid vinyl chloride tank 3 and the condenser 4 via pipes. The condenser 4 is connected to the liquid vinyl chloride tank 3 and the first heater 5 via pipes. The first heater 5 is connected to the inlet of the converter via a pipe.

[0047] The beneficial effects of adopting the above-mentioned further technical solution are as follows: The gas going to the condensation separation device is cooled by the first cooler. The condensate from the first cooler enters the liquid vinyl chloride tank. The gas cooled by the first cooler enters the condenser, where some of the gas (vinyl chloride, high-boiling substances) is condensed. The condensate from the condenser enters the liquid vinyl chloride tank. The uncondensed gas is heated by the heater, and the heated gas goes to the pre-converter stage. The gas going to the pre-converter stage is converted by the converter, forming a mixture with another gas stream. The gas going to the condensation separation device is cooled by the cooler and then enters the condenser again, where most of the vinyl chloride is condensed. The condensate enters the liquid vinyl chloride tank. The uncondensed gases, such as acetylene, hydrogen chloride, and vinyl chloride, are heated by the heater and participate in the reaction again before going to the pre-converter stage.

[0048] like Figure 1As shown, the evaporation device further includes a first evaporator 6, the liquid vinyl chloride tank 3 is connected to the first evaporator 6 through a pipeline, a pump 7 is installed on the pipeline between the liquid vinyl chloride tank 3 and the first evaporator 6, and the first evaporator 6 is connected to the converter outlet pipeline 1 through a pipeline.

[0049] The beneficial effects of adopting the above-mentioned further technical solution are as follows: Liquid vinyl chloride from the liquid vinyl chloride tank is pumped into the evaporator, where the vinyl chloride and other gases evaporated from the evaporator mix with another gas stream. The liquid vinyl chloride is pumped back into the evaporator, where the evaporated vinyl chloride is heated by a heater and mixed with the other gas stream. After cooling, the temperature of the mixture is >0°C, and it enters the purification unit (acid removal tower, water washing tower, alkali washing tower). The evaporator exchanges heat with circulating chilled water (containing calcium chloride or ethylene glycol), which is then cooled and sent to a cooler to cool the gas entering the condensation and separation unit. This reduces the acetylene content while maximizing the utilization of heat and cold; the equipment in the device is minimal; and the cooling energy released by the re-evaporation of the condensed vinyl chloride is precisely used to cool the gas.

[0050] like Figure 1 As shown, a second cooler 8 is further installed on the converter outlet pipe 1, and the first evaporator 6 is connected to the second cooler 8 and the purification device via a pipe; the second cooler 8 is connected to the liquid vinyl chloride tank 3 via a pipe.

[0051] The beneficial effect of adopting the above-mentioned further technical solution is that the second cooler is used to cool another gas stream. The other gas stream passes through the second cooler, and the cooled gas mixes with vinyl chloride and other gases evaporated from the evaporator to form a mixed gas. After mixing, the temperature is >0°C, and the mixture enters the purification device. The condensate from the second cooler enters the liquid vinyl chloride tank.

[0052] like Figure 1 As shown, the first evaporator 6 is further connected to a circulating chilled water pump 9 via a pipeline, the circulating chilled water pump 9 is connected to a circulating chilled water tank 10 via a pipeline, the first evaporator 6 is connected to the first cooler 2 and the second cooler 8 via pipelines, and the circulating chilled water tank 10 is connected to the first cooler 2 and the second cooler 8 via pipelines.

[0053] The beneficial effects of adopting the above-mentioned further technical solution are as follows: the water in the circulating chilled water tank (containing calcium chloride or ethylene glycol) is pumped out by the circulating chilled water pump, enters the evaporator through pipelines, and the circulating chilled water pipeline exiting the evaporator splits into two branches. One branch enters the first cooler, and the third circulating chilled water pipeline exiting the first cooler returns to the circulating chilled water tank (containing calcium chloride or ethylene glycol). The other branch enters the cooler, and the fourth circulating chilled water pipeline exiting the cooler returns to the circulating chilled water tank. This reduces the acetylene content while maximizing the utilization of heat and cold; the equipment in the device is less numerous; and the cooling energy released by the re-evaporation of condensed vinyl chloride is just enough to cool the gas.

[0054] like Figure 2 As shown, pump 7 is further connected to the first evaporator 6 and the second evaporator 11 respectively. The first evaporator 6 is connected to the second heater 12 through two pipes. The second heater 12 is connected to the converter outlet pipe 1 through a pipe. The second evaporator 11 is connected to the second heater 12 through a pipe.

[0055] The beneficial effects of adopting the above-mentioned further technical solution are that, due to the large amount of condensed vinyl chloride, some of the liquid vinyl chloride needs to be heated and evaporated with hot water (or steam), requiring the addition of an evaporator. The acetylene content entering the purification unit (deacidification tower, water washing tower, alkali washing tower) is very low, and the compression and distillation units operate safely and reliably. Liquid vinyl chloride from the tank is pumped out and divided into two streams. One stream of liquid vinyl chloride enters the first evaporator. The vinyl chloride and other gases evaporated in the first evaporator enter the heater for heating. The liquid entrained in the gas entering the heater also enters the first evaporator, where the heated gas mixes with the other gas stream. The liquid vinyl chloride from the tank is pumped out, and the other stream of liquid vinyl chloride enters the second evaporator. The vinyl chloride and other gases evaporated in the second evaporator enter the heater for heating, where the heated gas mixes with the other gas stream. The evaporator exchanges heat with circulating chilled water (containing calcium chloride or ethylene glycol). The circulating chilled water is cooled and then sent to a cooler to cool the gas entering the condensation and separation unit.

[0056] like Figure 1 As shown, the first heater 5 is further provided with a hot water inlet and a hot water outlet; the condenser 4 is provided with a deep chilled water inlet and a deep chilled water outlet; the liquid vinyl chloride tank 3 is connected to a high boiling point treatment device through a pipeline; and the second heater 12 is provided with a hot water inlet and a hot water outlet.

[0057] The beneficial effects of adopting the above-mentioned further technical solution are that the hot water for the heater can be from the conversion unit or from an external device. This facilitates selection and installation according to actual needs, improving applicability. The deep chilled water for the condenser comes from an external device. High-boiling-point substances in the liquid vinyl chloride tank are sent to the high-boiling-point substance treatment unit via a second pipeline.

[0058] like Figure 2As shown, the second evaporator 11 is further provided with a hot water inlet and a hot water outlet.

[0059] The beneficial effect of adopting the above-mentioned further technical solution is that the second evaporator exchanges heat through circulating hot water. That is, the evaporation of the evaporator is heated by the hot water.

[0060] like Figure 3 As shown, the circulating chilled water pump 9 is further connected to a distillation unit 13 via a pipeline, the distillation unit 13 is connected to the second evaporator 11 via a pipeline, and the second evaporator 11 is connected to the circulating chilled water tank 10 via a pipeline.

[0061] The beneficial effects of adopting the above-mentioned further technical solution are that, due to the large amount of vinyl chloride condensed, the large amount of cold energy released by the evaporation of vinyl chloride can be used for the cold energy required by the total condenser and the finished product condenser of the distillation unit, thus making great use of the cold energy released by the evaporator. The acetylene content entering the purification unit (deacid removal tower, water washing tower, alkali washing tower) is very low, and the operation of the compression and distillation unit is safe and reliable; the acetylene content is greatly reduced while maximizing the utilization of heat and cold. The evaporator absorbs heat during evaporation to cool the circulating chilled water, which then goes to the distillation unit (total condenser, finished product condenser) to condense vinyl chloride into a liquid state, making full use of the cold energy of evaporation. The circulating chilled water in the circulating chilled water tank (containing calcium chloride or ethylene glycol) is pumped by another pipeline to the total condenser and the finished product condenser of the distillation unit to condense vinyl chloride. After heat exchange with the total condenser and the finished product condenser, the return water pipeline goes into the evaporator, and the pipeline exiting the evaporator returns to the circulating chilled water tank.

[0062] The gases such as acetylene, hydrogen chloride, and vinyl chloride coming from the converter outlet manifold are separated into two streams before entering the purification unit: one stream goes to the purification unit, and the other goes to the condensation and separation unit.

[0063] The gas going to the condenser separation unit is cooled by the cooler and then enters the condenser. Most of the vinyl chloride is condensed, and the condensate enters the liquid vinyl chloride tank. The uncondensed gases, such as acetylene, hydrogen chloride, and vinyl chloride, are heated by the heater and participate in the reaction again before going to the converter.

[0064] Liquid vinyl chloride is pumped into the evaporator. The evaporated vinyl chloride is heated by a heater and mixed with another gas. After cooling, the temperature of the mixture is >0℃, and then it enters the purification device (acid removal tower, water washing tower, alkali washing tower).

[0065] The hot water for the heater can come from a conversion device or from an external device.

[0066] The evaporator exchanges heat with the circulating chilled water (containing calcium chloride or ethylene glycol), which is then cooled and sent to the cooler to cool the gas entering the condenser and separation unit.

[0067] The deep chilled water for the condenser comes from an external device.

[0068] This invention reduces the acetylene content in the gases from purification units (acid removal tower, water washing tower, alkali washing tower), compression, and distillation units, preventing the risk of explosion due to high acetylene content in the gases from compression and distillation units. The process is simple and energy-efficient. By adding this invention to existing production equipment, the system can meet the safety requirements of acetylene content >3% at the outlet of subsequent conversion units.

[0069] Furthermore, the present invention also provides a method for treating mixed gas at the outlet of a converter, based on a system for treating mixed gas at the outlet of a converter. The method includes: S1, gas enters the converter outlet pipeline through the outlet of the converter; wherein the gas includes acetylene, hydrogen chloride, and vinyl chloride; S2, the gas is divided into two streams in the converter outlet pipeline, one stream of gas enters a condensation and separation device; S3, after the gas is treated by the condensation and separation device, the uncondensed gas re-enters the converter for conversion; the condensed gas is mixed with the other stream of gas.

[0070] The beneficial effects of adopting the technical solution of this invention are as follows: Gas with an acetylene content >3% at the outlet of the downstream conversion unit is divided into two streams. One stream undergoes condensation and separation to separate acetylene and hydrogen chloride before entering the converter for further conversion. The condensed vinyl chloride is then evaporated and mixed with the other stream of gas, resulting in an acetylene content <3%, thus reducing the acetylene content in the gas before it enters subsequent units, allowing for safe production. The invention also fully considers the utilization of cold and heat, reducing the increased consumption of cooling capacity. Furthermore, it reduces the acetylene content in the gas going to the purification, compression, and distillation units, preventing the risk of explosion due to high acetylene content in the gas from the compression and distillation units. Finally, it meets the safety production requirements of an acetylene content >3% at the outlet of the downstream conversion unit.

[0071] Comparison of old and new technologies: Old technology: The current production equipment cannot meet the safety production requirements of acetylene content >3% at the outlet of the downstream conversion unit.

[0072] The new process technology provided by this invention adapts to the safety production requirement of acetylene content >3% at the outlet of the post-conversion unit. It requires only adding one unit of this invention without changing the existing production equipment. 1. It adapts to the safety production requirement of acetylene content >3% at the outlet of the post-conversion unit; 2. It requires only adding one unit of this patented device without changing the existing production equipment; 3. It can be adapted to mercury-free catalytic production equipment, representing a historic transformation in the calcium carbide method for producing polyvinyl chloride.

[0073] Process Method 1 like Figure 1As shown in the summary: Under certain circumstances, gases such as acetylene, hydrogen chloride, and vinyl chloride coming from the converter outlet main pipe (converter outlet pipe 1) may pose a safety hazard to the compression and distillation units if the acetylene content exceeds 3%. Therefore, it is necessary to reduce the acetylene content in the gas before it goes to the deacidification tower, water washing tower, alkali washing tower, compression and distillation units.

[0074] The method employed in this invention involves splitting the acetylene, hydrogen chloride, vinyl chloride, and other gases from the converter outlet manifold into two streams: one stream is condensed, and the other is not condensed.

[0075] The gas that passes through the condenser (condensation separation unit) is vinyl chloride. The acetylene, hydrogen chloride, and some vinyl chloride that do not condense after passing through the condenser are heated and then enter the converter for conversion to reduce the acetylene content.

[0076] The condensed vinyl chloride is vaporized through heat exchange with another gas (gas that does not pass through the condensation device). The vaporized vinyl chloride is mixed with the gas that does not undergo condensation. The acetylene content of the mixture is ≤3%, and the temperature is not lower than 0℃. The mixture is then fed into a purification device (acid removal tower, water washing tower, alkali washing tower). In this way, compression and distillation can be carried out safely without changing the equipment or process.

[0077] Option 1 has the following advantages: 1. It reduces the acetylene content while maximizing the utilization of heat and cold; 2. It requires fewer devices; 3. The cooling energy released by the re-evaporation of condensed vinyl chloride is just enough to cool the gas. The disadvantage is that due to the small amount of vinyl chloride condensed, the reduction in acetylene content is relatively small.

[0078] The process flow of Method 1: The acetylene, hydrogen chloride, vinyl chloride and other gases (>80℃) coming from the converter outlet main pipe (converter outlet pipe 1) are separated into two gas streams before entering the purification device. One gas goes to the condensation and separation device and the other gas goes to the purification device.

[0079] The gas going to the condensation and separation device is cooled by the first cooler 2. The condensate from the first cooler 2 enters the liquid vinyl chloride tank 3. The gas cooled by the first cooler 2 enters the condenser 4. Some of the gas (vinyl chloride, high-boiling substances) is condensed. The condensate from the condenser 4 enters the liquid vinyl chloride tank 3. The uncondensed gas goes to the first heater 5 for heating. The heated gas goes to the converter.

[0080] The liquid vinyl chloride in the liquid vinyl chloride tank 3 enters the first evaporator 6 via pump 7, and the vinyl chloride and other gases evaporated from the first evaporator 6 mix with another gas stream.

[0081] Another gas passes through the second cooler 8. The gas cooled by the second cooler 8 mixes with the vinyl chloride and other gases evaporated from the first evaporator 6 to form a mixed gas. After mixing, the temperature is >0℃ and enters the purification device (acid removal tower, water washing tower, alkali washing tower).

[0082] The first hot water enters the first heater 5, and the second hot water exits the first heater 5.

[0083] Water in the circulating chilled water tank 10 (containing calcium chloride or ethylene glycol) is pumped out by the circulating chilled water pump 9 and piped into the first evaporator 6. The circulating chilled water pipeline exiting the first evaporator 6 splits into two branches: one (the first circulating chilled water pipeline) enters the first cooler 2, and the third circulating chilled water pipeline exiting the first cooler 2 returns to the circulating chilled water tank 10 (containing calcium chloride or ethylene glycol). The other (the second circulating chilled water pipeline) enters the second cooler 8, and the fourth circulating chilled water pipeline exiting the second cooler 8 returns to the circulating chilled water tank 10.

[0084] First-stage chilled water (containing calcium chloride or ethylene glycol) from the outside enters condenser 4, and second-stage chilled water exits condenser 4.

[0085] The condensate from the second cooler 8 enters the liquid vinyl chloride tank 3.

[0086] The gas before going to the converter (the heated gas) is converted by the converter to form a gas that is converted by the converter and then mixed with another gas.

[0087] The high-boiling-point substance in the liquid vinyl chloride tank 3 is sent to the high-boiling-point substance treatment unit via the second pipeline.

[0088] Process Method Two like Figure 2 As shown in the summary: Under certain circumstances, gases such as acetylene, hydrogen chloride, and vinyl chloride coming from the converter outlet main pipe (converter outlet pipe 1) may pose a safety hazard to the compression and distillation units if the acetylene content exceeds 3%. Therefore, it is necessary to reduce the acetylene content in the gas before it goes to the deacidification tower, water washing tower, alkali washing tower, compression and distillation units.

[0089] The method adopted in this invention is to separate the acetylene, hydrogen chloride, vinyl chloride and other gases from the converter outlet main pipe (converter outlet pipe 1) into two streams, one of which enters the condensation device (condensation separation device); the other enters the cooling device (second cooler).

[0090] The gas that passes through the condenser (condensation separation unit) is vinyl chloride. The acetylene, hydrogen chloride, and some vinyl chloride that do not condense after passing through the condenser (condensation separation unit) are heated and then enter the converter for conversion to reduce the acetylene content in the compression and distillation units.

[0091] The condensed vinyl chloride is vaporized by exchanging heat with another gas (the gas that does not pass through the condensation device, i.e. the gas that goes to the cooling device). The vaporized vinyl chloride is mixed with the gas that does not undergo condensation. The acetylene content of the mixture is ≤3% and the temperature is not lower than 0℃. It is then fed into the purification device (acid removal tower, water washing tower, alkali washing tower). In this way, compression and distillation can be carried out safely without changing the equipment or process.

[0092] Because of the large amount of vinyl chloride that condenses, some of the liquid vinyl chloride needs to be heated and evaporated with hot water (or steam), requiring the addition of an evaporator.

[0093] Option 2 has the following drawbacks: 1. The acetylene content in the purification unit (deacidification tower, water washing tower, alkali washing tower) is very low, and the compression and distillation units operate safely and reliably; the drawback is that due to the large amount of condensation, additional heating is required.

[0094] Process flow: Before entering the purification unit (acid removal tower, water washing tower, alkali washing tower), the gases such as acetylene, hydrogen chloride, and vinyl chloride from the converter outlet main pipe (converter outlet pipe 1) go to the condensation separation unit in part and to the cooling unit in the other part.

[0095] The gas going to the condenser separation device is cooled by the cooler (first cooler 2), the condensate enters the liquid vinyl chloride tank 3, the cooled gas enters the condenser 4, some vinyl chloride is condensed, the condensate enters the liquid vinyl chloride tank 3, the uncondensed gas goes to the heater (first heater 5) for heating, and the heated gas goes to the converter.

[0096] Liquid vinyl chloride is pumped out from tank 3 and split into two streams. One stream of liquid vinyl chloride enters the first evaporator 6. The vinyl chloride and other gases evaporated from the first evaporator 6 enter the heater (second heater 11) for heating. The liquid entrained in the gas entering the heater (second heater 11) enters the first evaporator 6. After heating, the gas mixes with the other stream of gas.

[0097] Liquid vinyl chloride is pumped out from liquid vinyl chloride tank 3 via pump 7, and another stream of liquid vinyl chloride enters the second evaporator 11. The vinyl chloride and other gases evaporated from the second evaporator 11 enter the second heater 11 for heating. After heating, the gas mixes with the other gas stream.

[0098] The acetylene, hydrogen chloride, vinyl chloride, and other gases from the converter outlet main pipe (converter outlet pipe 1) go to the cooler (second cooler 8) before entering the purification unit (acid removal tower, water washing tower, alkali washing tower). The condensate enters the liquid vinyl chloride tank 3. The cooled gas mixes with the gas heated by the second heater 11, and the temperature is not lower than 0°C before entering the purification unit (acid removal tower, water washing tower, alkali washing tower). In this way, compression and distillation can be safely produced without changing the equipment or process.

[0099] The circulating chilled water in the circulating chilled water tank 10 (containing calcium chloride or ethylene glycol) is pumped out by the circulating chilled water pump 9 and piped into the first evaporator 6. The circulating chilled water exiting the first evaporator 6 is divided into two branches: one branch enters the second cooler 8 and the circulating chilled water exiting the second cooler 8 returns to the circulating chilled water tank 10 through a pipeline; the other branch enters the first cooler 2 and the circulating chilled water in the first cooler 2 returns to the circulating chilled water tank 10 through a pipeline.

[0100] Deep chilled water from outside (with added calcium chloride or ethylene glycol) enters condenser 4 and exits condenser 4.

[0101] In the first heater 5, the first hot water enters the first heater, and the second hot water exits the first heater.

[0102] In the second evaporator 11, the first hot water enters the second evaporator and the second hot water exits the second evaporator.

[0103] The first hot water enters the second heater 12, and the second hot water exits the second heater.

[0104] The gas before going to the converter is mixed with another gas after passing through the converter.

[0105] The high-boiling-point substance in the liquid vinyl chloride tank 3 is sent to the high-boiling-point substance treatment unit via pipeline.

[0106] Process Method 3 like Figure 3 As shown in the summary: Under certain circumstances, gases such as acetylene, hydrogen chloride, and vinyl chloride coming from the converter outlet manifold can pose safety hazards to the compression and distillation units if the acetylene content exceeds 3%. Therefore, it is necessary to reduce the acetylene content in the gas before it passes through the deacidification tower, water washing tower, alkali washing tower, compression, and distillation units.

[0107] The method employed in this invention involves separating the acetylene, hydrogen chloride, vinyl chloride, and other gases from the converter outlet manifold into two streams: one stream enters a condensation device (condensation separation device), and the other stream enters a cooling device.

[0108] The gas that passes through the condenser (condensation separation unit) is vinyl chloride. The acetylene, hydrogen chloride, and some vinyl chloride that do not condense after passing through the condenser (condensation separation unit) are heated and then enter the converter for conversion to reduce the acetylene content in the compression and distillation units.

[0109] The condensed vinyl chloride vaporizes through heat exchange with the gas that needs to be cooled. The vaporized vinyl chloride mixes with the gas that is not condensed. The resulting mixture has an acetylene content of ≤3% and a temperature not lower than 0℃. It then enters the purification device (acid removal tower, water washing tower, alkali washing tower). In this way, compression and distillation can be carried out safely without changing the equipment or process.

[0110] Since a large amount of vinyl chloride is condensed, the large amount of cold energy released by the evaporation of vinyl chloride can be used for the total condenser and the finished product condenser of the distillation unit 13, thus making great use of the cold energy released by the evaporator.

[0111] Option three has the following advantages: 1. The acetylene content in the purification devices (deacidification tower, water washing tower, alkali washing tower) is very low, and the compression and distillation units operate safely and reliably; 2. It significantly reduces the acetylene content while maximizing the utilization of heat and cold. The disadvantage is the large amount of condensation.

[0112] The difference between Method 3 and Method 2 is that in Method 3, the evaporator (second evaporator) absorbs heat to cool the circulating chilled water, which then goes to the distillation unit (total condenser, finished product condenser) to condense vinyl chloride into a liquid state, fully utilizing the cooling capacity of the evaporation. In Method 2, the evaporator uses hot water to provide heat.

[0113] The process flow of Method 3: Before entering the purification unit (acid removal tower, water washing tower, alkali washing tower), the acetylene, hydrogen chloride, vinyl chloride and other gases from the converter outlet main pipe (converter outlet pipe 1) go to the condensation separation unit in part and to the cooling unit in the other part.

[0114] The gas going to the condensation separation device is cooled by the first cooler 2, the condensate enters the liquid vinyl chloride tank 3, the cooled gas enters the condenser 4, some vinyl chloride is condensed, the condensate enters the liquid vinyl chloride tank 3, the uncondensed gas goes to the first heater 5 for heating, and the heated gas goes to the converter.

[0115] Liquid vinyl chloride in liquid vinyl chloride tank 3 is pumped out by pump 7 and split into two streams. One stream of liquid vinyl chloride enters the first evaporator 6. The vinyl chloride and other gases evaporated from the first evaporator 6 enter the second heater 12 for heating. The liquid entrained in the gas entering the second heater 12 enters the first evaporator 6. After heating, the gas mixes with the other stream of gas.

[0116] Liquid vinyl chloride in liquid vinyl chloride tank 3 is pumped out by pump 7, and another stream of liquid vinyl chloride enters the second evaporator 11. The vinyl chloride and other gases evaporated from the second evaporator 11 enter the second heater 12 for heating. After heating, the gas mixes with the other gas.

[0117] The acetylene, hydrogen chloride, vinyl chloride, and other gases from the converter outlet manifold enter the purification unit (acid removal tower, water washing tower, alkali washing tower). Another portion of the gas goes to the second cooler 8, and the condensate enters the liquid vinyl chloride tank 3. The cooled gas mixes with another gas and the temperature is not lower than 0°C before entering the purification unit (acid removal tower, water washing tower, alkali washing tower). In this way, compression and distillation can be safely carried out without changing the equipment or process.

[0118] The circulating chilled water in the circulating chilled water tank 10 (containing calcium chloride or ethylene glycol) is pumped out by the circulating chilled water pump 9. One pipeline enters the first evaporator 6. The circulating chilled water exiting the first evaporator 6 splits into two branches: one enters the second cooler 8, and the circulating chilled water exiting the second cooler 8 returns to the circulating chilled water tank 10 through a pipeline; the other enters the first cooler 2, and the circulating chilled water exiting the first cooler 2 returns to the circulating chilled water tank 10 through a pipeline.

[0119] Deep chilled water from outside (with added calcium chloride or ethylene glycol) enters condenser 4 and exits condenser 4.

[0120] In the first heater 5, the first hot water enters the first heater, and the second hot water exits the first heater.

[0121] The circulating chilled water in the circulating chilled water tank 10 (containing calcium chloride or ethylene glycol) is sent to the total condenser and finished product condenser of the distillation unit 13 via another pipeline by the circulating chilled water pump 9 to condense vinyl chloride. After heat exchange with the total condenser and finished product condenser, it enters the second evaporator 11 through the return water pipeline and returns to the circulating chilled water tank 10 through the pipeline after exiting the second evaporator 11.

[0122] The first hot water enters the second heater 12, and the second hot water exits the second heater.

[0123] The gas before going to the converter is mixed with another gas after passing through the converter.

[0124] The high-boiling-point substance in the liquid vinyl chloride tank 3 is sent to the high-boiling-point substance treatment unit via pipeline.

[0125] Because the current calcium carbide-based PVC production process uses mercuric chloride catalyst with high conversion efficiency, the acetylene content at the outlet of the later conversion unit is less than 3%, which will not affect the safety of the distillation unit (see the calcium carbide-based PVC production process description below).

[0126] 1. Due to the restrictions of the Minamata Treaty, mercuric chloride catalysts will no longer be allowed to be used in a few years. Currently, research institutes, R&D companies, and manufacturing enterprises are exploring mercury-free catalysts, with gold-based and copper-based catalysts being the most common subjects of their experiments.

[0127] 2. Gold-based catalysts are comparable to currently used mercuric chloride catalysts in terms of both catalytic efficiency and service life, but gold-based catalysts are expensive, which affects their practical use.

[0128] 3. Copper-based catalysts are currently widely used, but their conversion efficiency and lifespan are lower than those of mercuric chloride catalysts. However, copper-based catalysts are cheaper, and with the maturation of research and development technology, they are expected to be widely adopted. The disadvantage is that the conversion efficiency of copper-based catalysts decreases rapidly, and the acetylene content at the outlet of the downstream converter is >3%. Current calcium carbide-based PVC production processes are not suitable for this situation; this invention is best suited for copper-based catalysts.

[0129] This invention is based on the use of copper-based catalysts in existing equipment. Since copper-based catalysts have lower conversion efficiency and lifespan than mercuric chloride catalysts, an acetylene content >3% at the outlet of the later-stage conversion unit can affect the safety of the distillation unit. To reduce the acetylene content at the outlet of the later-stage conversion unit, this invention splits the gas with an acetylene content >3% into two streams. One stream is condensed and separated to remove acetylene and hydrogen chloride before entering the converter for further conversion. The condensed vinyl chloride is then evaporated and mixed with the other stream, resulting in an acetylene content <3% before entering the subsequent units, allowing for safe production.

[0130] Description of the calcium carbide method for producing polyvinyl chloride: In the calcium carbide method of PVC production, 1. Acetylene gas (purity ≥98.5%, impurities include nitrogen (0.5%), small amounts of methane, oxygen (0.05%), and gaseous water), and hydrogen chloride gas (purity ≥93%, impurities include hydrogen (6.86%), gaseous water, and oxygen (<0.5%)) are mixed with each other (production specifications require an acetylene / hydrogen chloride molar ratio of 1:1.05-1.1). The gas contains ≤0.06% water. After being heated by a preheater, the mixture enters the first-stage converter. The converter tubes are filled with activated carbon, also called a catalyst, to adsorb the catalyst. Within the converter tubes, the acetylene gas and hydrogen chloride react to produce vinyl chloride through catalysis. Due to incomplete reaction, the process requires the acetylene content at the outlet of the first stage to be ≤30%. The vinyl chloride gas from the first stage, along with unreacted acetylene, hydrogen chloride, and impurities, enters the second-stage converter. Within the converter tubes, the acetylene gas and hydrogen chloride react to produce vinyl chloride through catalysis. Due to incomplete reaction, the process requires that the acetylene content at the outlet of the downstream group be ≤3%.

[0131] 2. The gas from the downstream converter (vinyl chloride, acetylene, hydrogen chloride, and impurities in the raw material gas (hydrogen, nitrogen, methane, oxygen) and byproducts such as carbon dioxide and high- and low-boiling-point substances) passes through an adsorption catalyst unit to remove the catalyst entrained in the gas. The gas is then cooled, passes through a deacidification tower and a water washing tower to remove hydrogen chloride, and passes through an alkaline washing tower to remove trace amounts of carbon dioxide and hydrogen chloride. It then goes to the compression process for compression, and finally to the distillation process's total condenser (cooled by 7°C water) to condense most of the vinyl chloride. Uncondensed vinyl chloride gas, along with acetylene, hydrogen, nitrogen, methane, and oxygen, enters the tail gas condenser (-26 to -35℃ chilled water), where some vinyl chloride is condensed again. The uncondensed vinyl chloride gas, along with acetylene, hydrogen, nitrogen, methane, and oxygen from the tail gas condenser, enters the tail gas adsorption unit. The separated nitrogen, methane, oxygen, and a small amount of hydrogen are released into the atmosphere. The separated vinyl chloride and acetylene gas go to the converter, where acetylene participates in the reaction again to produce vinyl chloride. The hydrogen goes to the hydrogen chloride synthesis unit to react with chlorine to produce hydrogen chloride.

[0132] Liquid vinyl chloride is distilled through a distillation column until its purity reaches 99.9%, and then sent to a polymerization unit to produce PVC powder.

[0133] "The uncondensed vinyl chloride gas, along with acetylene, hydrogen, nitrogen, methane, and oxygen from the exhaust gas condenser, enters the exhaust gas adsorption device." Due to the continuous condensation of vinyl chloride, the acetylene, hydrogen, methane, and oxygen in this section of the pipeline from the exhaust gas condenser outlet to the exhaust gas adsorption device are highly concentrated. The gauge pressure of this section of the pipeline is 5.0-5.5 MPa. Acetylene can spontaneously decompose under high pressure and concentration. At the same time, acetylene with oxygen, hydrogen with oxygen, and methane with oxygen will also explode when their concentrations reach a certain level.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; 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; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A converter outlet mixed gas treatment system, characterized in that, include: The system includes a converter outlet pipe, a condenser separation device, and an evaporator. The two ends of the converter outlet pipe are connected to the converter outlet and the purification device inlet, respectively. The first end of the condenser separation device and the first end of the evaporator are both connected to the converter outlet pipe. The second end of the condenser separation device is connected to the second end of the evaporator. The first end of the condenser separation device and the first end of the evaporator are both located between the converter outlet and the purification device inlet. The third end of the condenser separation device is connected to the converter inlet via a pipe.

2. The converter outlet mixed gas treatment system according to claim 1, characterized in that, The condensation separation device includes: a first cooler, a liquid vinyl chloride tank, a condenser, and a first heater. The converter outlet pipe is connected to the first cooler via a pipe. The first cooler is connected to the liquid vinyl chloride tank and the condenser via pipes. The condenser is connected to the liquid vinyl chloride tank and the first heater via pipes. The first heater is connected to the converter inlet via a pipe.

3. The converter outlet mixed gas treatment system according to claim 2, characterized in that, The evaporation device includes a first evaporator, the liquid vinyl chloride tank is connected to the first evaporator through a pipeline, a pump is installed on the pipeline between the liquid vinyl chloride tank and the first evaporator, and the first evaporator is connected to the converter outlet pipeline through a pipeline.

4. The converter outlet mixed gas treatment system according to claim 3, characterized in that, A second cooler is installed on the outlet pipe of the converter, and the first evaporator is connected to the second cooler and the purification device via a pipeline; the second cooler is connected to the liquid vinyl chloride tank via a pipeline.

5. A converter outlet mixed gas treatment system according to claim 4, characterized in that, The first evaporator is connected to a circulating chilled water pump via a pipeline, and the circulating chilled water pump is connected to a circulating chilled water tank via a pipeline. The first evaporator is connected to the first cooler and the second cooler via pipelines, and the circulating chilled water tank is connected to the first cooler and the second cooler via pipelines.

6. A converter outlet mixed gas treatment system according to claim 5, characterized in that, The pump is connected to the first evaporator and the second evaporator respectively. The first evaporator is connected to the second heater through two pipes. The second heater is connected to the outlet pipe of the converter through a pipe. The second evaporator is connected to the second heater through a pipe.

7. A converter outlet mixed gas treatment system according to claim 6, characterized in that, The first heater is equipped with a hot water inlet and a hot water outlet; the condenser is equipped with a deep chilled water inlet and a deep chilled water outlet; the liquid vinyl chloride tank is connected to a high-boiling-point treatment device via a pipeline; the second heater is equipped with a hot water inlet and a hot water outlet.

8. A converter outlet mixed gas treatment system according to claim 7, characterized in that, The second evaporator is equipped with a hot water inlet and a hot water outlet.

9. A converter outlet mixed gas treatment system according to claim 7, characterized in that, The circulating chilled water pump is connected to a distillation unit via a pipeline, the distillation unit is connected to the second evaporator via a pipeline, and the second evaporator is connected to the circulating chilled water tank via a pipeline.

10. A method for treating a mixed gas at the outlet of a converter, characterized in that, According to any one of claims 1 to 9, the converter outlet mixed gas treatment system includes a method for treating the converter outlet mixed gas as follows: S1. The gas enters the converter outlet pipeline through the converter outlet; the gas includes acetylene, hydrogen chloride, and vinyl chloride. S2. The gas is divided into two streams in the converter outlet pipeline, and one stream enters the condensation and separation unit. S3. After the gas is processed by the condensation and separation device, the uncondensed gas enters the converter for conversion; the condensed gas is mixed with another gas stream.

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