A continuous recovery system for xylene produced from vinyl acetylene

Abstract

The utility model relates to the field of chemical automatic control technology especially relates to a kind of continuous recovery system of dimethylbenzene of vinyl acetylene production, the continuous recovery system of dimethylbenzene of vinyl acetylene production, including raw material pretreatment unit, vacuum distillation unit, on-line monitoring unit, automation control unit, material conveying unit and tail gas treatment unit, each unit is connected by pipeline and control circuit closed loop.Raw material pretreatment unit is sent into vacuum distillation unit after stirring polymerization, preheating and filtration, and the separation of dimethylbenzene and high polymer is completed in packing tower;On-line monitoring unit obtains tower kettle material parameter in real time by density sensor and concentration detector, and the automatic regulation and control of material conveying is realized by automation control unit, when high polymer concentration reaches 45-50%, it is automatically transported to storage tank, and when it is less than 45%, valve is automatically closed, without parking operation;Tail gas treatment unit purifies tail gas by frozen dimethylbenzene spraying.

Description

Technical Field

[0001] This utility model relates to the technical field, specifically to a continuous recovery system for the production of xylene from vinyl acetylene. Background Technology

[0002] In the calcium carbide process for producing chloroprene rubber, the acetylene dimerization step generates byproducts DVA (disinylenyne) and polymers. When xylene is used as an absorbent to absorb vinyl acetylene in the reaction gas, xylene simultaneously adsorbs both DVA and polymers, leading to a gradual decrease in purity. In the traditional process, some of the xylene after desorbing MVA (methylvinyl acetylene) needs to enter a feed buffer tank to polymerize DVA and polymers into high-boiling-point substances, which are then fed into a xylene recovery tower for vacuum distillation to recover xylene. When the polymer concentration at the bottom of the tower reaches 50%, the system needs to be shut down for cooling, and the bottom material is sent to the paint storage tanks in the tank area for disposal. On average, a start-up and shutdown operation is required every 16-20 hours.

[0003] This traditional operation has significant drawbacks: First, the start-up and shutdown procedures are complex, requiring manual adjustment of valves, temperature, pressure, and other parameters, resulting in high labor intensity and susceptibility to product quality fluctuations due to operational errors. Second, the reboiler needs to be cooled by circulating water during shutdown, and the cooling water needs to be discharged and the temperature raised again during restart, increasing wastewater discharge. Furthermore, frequent temperature fluctuations severely impact the reboiler's lifespan. Third, the heating process consumes a large amount of steam, and the large volume of condensate discharge leads to energy waste. Temperature fluctuations also cause unstable xylene recovery rates, increasing production costs. Therefore, there is an urgent need for a xylene recovery system that can achieve continuous operation, automated control, and energy efficiency. Therefore, we propose a continuous recovery system for the production of xylene from vinyl acetylene. Utility Model Content

[0004] The purpose of this invention is to provide a continuous recovery system for the production of xylene from vinyl acetylene, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: A continuous xylene recovery system for vinyl acetylene production: comprising a raw material pretreatment unit, a vacuum distillation unit, an online monitoring unit, an automated control unit, a material conveying unit, and a tail gas treatment unit, wherein each unit is sequentially connected via pipelines and control lines to form a closed-loop system; the raw material pretreatment unit includes a xylene feed buffer tank, a preheater, and a filter; the inlet of the xylene feed buffer tank is connected to the xylene outlet of the vinyl acetylene absorption process; the tank is equipped with a stirring device and a temperature sensor; the stirring device has a power of 1.5-3kW and its speed can be adjusted within the range of 50-200r / min via a frequency converter; the preheater adopts a shell-and-tube heat exchanger with the heat source being secondary steam from the top of the recovery tower, and the heat exchange area is 10-20㎡; the filter is a basket filter with a filter element material of 316L stainless steel and a filtration accuracy of 5-10μm; the vacuum distillation unit includes a xylene recovery tower, a reboiler, a tower top condenser, and a vacuum unit; the xylene recovery tower has a height of 15-25m and a diameter of 1-1.5m. The packed tower is filled with stainless steel corrugated packing and has a theoretical number of 20-30 plates. Temperature and pressure monitoring points are set at intervals of 2-3m along the tower body. The pressure at the top of the tower is controlled between -0.08 and -0.09 MPa (absolute pressure). The reboiler is a horizontal thermosiphon type with a heating area of ​​15-25㎡. The heat source is 0.3-0.5MPa saturated steam, and the heating amount is controlled by a steam regulating valve. The condenser at the top of the tower is a two-pass shell-and-tube heat exchanger with a heat exchange area of ​​20-30㎡. The vacuum unit uses a water ring vacuum pump with a pumping capacity of 50-100m³ / h and is equipped with a gas-liquid separator. Through the synergistic effect of each unit, continuous recovery of xylene and stable output of polymers are achieved.

[0006] Preferably, the online monitoring unit includes a density sensor, a concentration detector, and temperature and pressure transmitters. The density sensor is installed on the outlet pipe of the paint circulation pump and uses a differential pressure density meter with a measurement range of 800-1000 kg / m³ and an accuracy of ±0.5 kg / m³. The concentration detector is a near-infrared online analyzer installed on the bottom discharge pipe of the tower, with a measurement range of 0-100% and an accuracy of ±1%, which cross-validates the data from the density sensor. The temperature and pressure transmitters are installed at the top of the recovery tower, the bottom of the tower, and the inlet and outlet of the reboiler, respectively, and are explosion-proof, with a measurement temperature range of 0-200℃ and a pressure range of -0.1 to 0 MPa, and a data sampling frequency of 1 time / second. Both the density sensor and the concentration detector are equipped with dual redundant probes. When one probe fails, the system automatically switches to the backup probe and triggers an alarm.

[0007] Preferably, the automated control unit includes a DCS control system, a PLC control cabinet, and a human-machine interface. The DCS control system adopts a redundant design and includes a data acquisition module, a logic control module, and an alarm module. It can receive real-time data from the online monitoring unit and output control signals according to preset logic. The PLC control cabinet is equipped with relays, contactors, and safety interlock devices to control the start, stop, and opening of equipment such as the paint circulation pump, steam regulating valve, and reflux valve, with a response time ≤0.5 seconds. The human-machine interface is a 19-inch touch screen that can display system flowcharts, real-time parameters, historical trends, and alarm information, and supports manual / automatic mode switching. The automated control unit has a safety interlock logic. When the pressure at the top of the recovery tower exceeds -0.07MPa, the temperature at the bottom of the tower exceeds 150℃, or the polymer concentration exceeds 60%, the system automatically cuts off the steam supply and initiates an emergency shutdown procedure, while simultaneously opening the vent valve at the top of the tower and the emergency discharge valve at the bottom of the tower.

[0008] Preferably, the material conveying unit includes a xylene product tank, a paint storage tank, a conveying pump, and a valve assembly. The xylene product tank is a horizontal tank with a volume of 5-10 m³, equipped with a level gauge and a breather valve, and has an insulation layer at the bottom. The paint storage tank is a vertical tank with a volume of 10-20 m³, made of Q235B carbon steel, and has an anti-corrosion treatment on the inner wall. The conveying pump is a magnetically driven centrifugal pump with a flow rate of 5-10 m³ / h and a head of 20-30 m. The valve assembly includes a pneumatic regulating valve, a shut-off valve, and a check valve. The pneumatic regulating valve has a response time of ≤1 second and can automatically open and close according to the signal from the automation control unit. A reflux distributor is provided on the outlet pipe of the condenser at the top of the xylene recovery tower. It adopts an electric three-way valve structure and can accurately adjust the ratio of reflux liquid to product liquid, with a reflux ratio control accuracy of ±0.1.

[0009] Preferably, the exhaust gas treatment unit includes an exhaust gas absorption tower, a refrigeration unit, and a circulating pump. The exhaust gas absorption tower is a packed tower with a height of 8-12m and a diameter of 0.5-1m, filled with polypropylene stepped ring packing. Xylene at -10℃ is sprayed from the top of the tower. The refrigeration unit is a screw chiller with a cooling capacity of 10-20kW to ensure that the temperature of the spray liquid is stable between -12 and -8℃. The circulating pump has a flow rate of 8-15m³ / h, which transports the xylene at the bottom of the absorption tower to the refrigeration unit for cooling and recycling. The top of the exhaust gas absorption tower is equipped with a demister made of polytetrafluoroethylene. The exhaust gas after absorption is tested by an online VOCs detector and meets the standard (concentration ≤50mg / m³) before being discharged.

[0010] Preferably, the xylene feed buffer tank is equipped with 4-6 baffles, which are evenly distributed along the inner wall of the tank and have a height of 1 / 2-2 / 3 of the tank height; the reboiler steam inlet pipe is equipped with a condensate recovery device, including a steam trap, a condensate tank and a pressurizing pump, which can recover the high-temperature condensate with a temperature ≥100℃ generated by the reboiler to the boiler room for reuse, with a water saving rate of 20-30%.

[0011] Preferably, the system acquires real-time data on the density of the bottom liquid and the concentration of the polymer through an online monitoring unit. When the online density at the outlet of the paint circulation pump reaches 915 kg / m³ (corresponding to a concentration of 45-50%), the automated control unit automatically opens the regulating valve at the outlet of the paint circulation pump to transport qualified paint to the paint storage tank in the tank area. During the transportation process, the xylene recovery system maintains continuous pumping and distillation without the need for shutdown and cooling. When the online density detects a concentration below 45%, the system automatically closes the regulating valve to the tank area, achieving continuous recovery of xylene and continuous transportation of qualified paint. Compared with the traditional process, the steam consumption is reduced by 15-20%, and the purity of the xylene product at the top of the tower is ≥99.5%.

[0012] Compared with the prior art, the beneficial effects of this utility model are: I. Achieve continuous production and reduce operational intensity Traditional processes require shutdowns every 16-20 hours to process the polymer in the reboiler, resulting in complex start-up and shutdown procedures and high labor intensity. This system uses an online monitoring unit to acquire real-time data on the reboiler liquid density and polymer concentration, combined with an automated control unit to achieve fully automated control of material delivery: when the online density at the paint circulation pump outlet reaches 915 kg / m³ (corresponding to a concentration of 45-50%), the regulating valve automatically opens to deliver qualified paint; when the concentration falls below 45%, the valve automatically closes, eliminating the need for shutdowns for cooling or manual intervention. This design completely solves the problem of frequent start-ups and shutdowns, significantly reduces the workload of DCS operators and on-site personnel, lowers the risk of production fluctuations due to human error, and significantly improves production continuity and stability.

[0013] II. Extend equipment lifespan and reduce maintenance costs In traditional processes, the reboiler requires frequent cooling (through circulating water) and heating (after draining the cooling water) as the system operates. These rapid temperature changes can lead to material fatigue and severely impact the system's lifespan. This system, designed for continuous and stable operation, eliminates the need for the reboiler to undergo repeated drastic temperature fluctuations, maintaining a consistently stable heating state. This fundamentally avoids damage from frequent thermal shocks and significantly extends the lifespan of core equipment such as the reboiler and recovery tower. Simultaneously, it reduces mechanical wear caused by frequent start-ups and shutdowns, lowers maintenance frequency and costs, and improves the overall operational efficiency of the production equipment.

[0014] III. Conserve energy consumption and improve economic efficiency In traditional processes, each reboiler heating requires a large amount of steam, and the cooling process results in significant circulating water discharge, leading to substantial energy waste. This system achieves energy savings and reduced consumption through the following design features: First, continuous and stable operation ensures consistent reboiler heating demand, avoiding the extra steam consumption associated with frequent heating. Second, a condensate recovery device is installed in the reboiler steam inlet pipe to recover high-temperature condensate (≥100℃) for reuse in the boiler room, achieving a water saving rate of 20-30%. Third, the preheater utilizes secondary steam from the top of the recovery tower as a heat source, realizing cascaded energy utilization. Overall, this system reduces steam consumption by 15-20% compared to traditional processes, significantly reducing energy costs and improving production efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall system flow structure of this utility model; Figure 2 This is a schematic diagram of the core process structure of vacuum distillation according to this utility model; Figure 3 This is a schematic diagram of the automatic control logic structure of this utility model. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Please see Figure 1-3A continuous xylene recovery system for vinyl acetylene production includes a raw material pretreatment unit, a vacuum distillation unit, an online monitoring unit, an automated control unit, a material conveying unit, and a tail gas treatment unit. These units are sequentially connected via pipelines and control lines to form a closed-loop system. The raw material pretreatment unit includes a xylene feed buffer tank, a preheater, and a filter. The inlet of the xylene feed buffer tank is connected to the xylene outlet of the vinyl acetylene absorption process. The tank is equipped with a stirring device and a temperature sensor. The stirring device has a power of 1.5-3kW and its speed can be adjusted within the range of 50-200 r / min via a frequency converter. The preheater uses a shell-and-tube heat exchanger with secondary steam from the top of the recovery tower as the heat source. The heat exchange area is 10-20㎡. The filter is a basket filter with a filter element made of 316L stainless steel and a filtration accuracy of 5-10μm. The vacuum distillation unit includes a xylene recovery tower, a reboiler, a top condenser, and a vacuum unit. The xylene recovery tower is 15-25m high and 1-1.5m in diameter. The packed tower is filled with stainless steel corrugated packing and has a theoretical number of 20-30 plates. Temperature and pressure monitoring points are set at intervals of 2-3m along the tower body. The pressure at the top of the tower is controlled between -0.08 and -0.09 MPa (absolute pressure). The reboiler is a horizontal thermosiphon type with a heating area of ​​15-25㎡. The heat source is 0.3-0.5MPa saturated steam, and the heating amount is controlled by a steam regulating valve. The condenser at the top of the tower is a two-pass shell-and-tube heat exchanger with a heat exchange area of ​​20-30㎡. The vacuum unit uses a water ring vacuum pump with a pumping capacity of 50-100m³ / h and is equipped with a gas-liquid separator. Through the synergistic effect of each unit, continuous recovery of xylene and stable output of polymers are achieved.

[0018] Please see Figure 1-3 The online monitoring unit includes a density sensor, a concentration detector, and temperature and pressure transmitters. The density sensor is installed on the outlet pipe of the paint circulation pump and uses a differential pressure density meter with a measurement range of 800-1000 kg / m³ and an accuracy of ±0.5 kg / m³. The concentration detector is a near-infrared online analyzer installed on the bottom discharge pipe of the tower, with a measurement range of 0-100% and an accuracy of ±1%, which cross-validates the data from the density sensor. The temperature and pressure transmitters are installed at the top of the recovery tower, the bottom of the tower, and the inlet and outlet of the reboiler, respectively. They are explosion-proof and have a measurement temperature range of 0-200℃ and a pressure range of -0.1 to 0 MPa, with a data sampling frequency of 1 time / second. Both the density sensor and the concentration detector are equipped with dual redundant probes. When one probe fails, the system automatically switches to the backup probe and triggers an alarm.

[0019] Please see Figure 1-3The automated control unit includes a DCS control system, a PLC control cabinet, and a human-machine interface. The DCS control system adopts a redundant design and includes a data acquisition module, a logic control module, and an alarm module. It can receive real-time data from the online monitoring unit and output control signals according to preset logic. The PLC control cabinet is equipped with relays, contactors, and safety interlock devices to control the start, stop, and opening of equipment such as the paint circulation pump, steam regulating valve, and reflux valve, with a response time ≤0.5 seconds. The human-machine interface is a 19-inch touch screen that can display system flowcharts, real-time parameters, historical trends, and alarm information, and supports manual / automatic mode switching. The automated control unit has a safety interlock logic. When the pressure at the top of the recovery tower exceeds -0.07MPa, the temperature at the bottom of the tower exceeds 150℃, or the polymer concentration exceeds 60%, the system automatically cuts off the steam supply and initiates an emergency shutdown procedure, while simultaneously opening the vent valve at the top of the tower and the emergency discharge valve at the bottom of the tower.

[0020] Please see Figure 1-3 The material conveying unit includes a xylene product tank, a paint storage tank, a conveying pump, and a valve assembly. The xylene product tank is a horizontal tank with a volume of 5-10 m³, equipped with a level gauge and a breather valve, and has an insulation layer at the bottom. The paint storage tank is a vertical tank with a volume of 10-20 m³, made of Q235B carbon steel, and has an anti-corrosion inner wall. The conveying pump is a magnetically driven centrifugal pump with a flow rate of 5-10 m³ / h and a head of 20-30 m. The valve assembly includes a pneumatic regulating valve, a shut-off valve, and a check valve. The pneumatic regulating valve has a response time of ≤1 second and can automatically open and close according to the signal from the automation control unit. The reflux distributor is installed on the outlet pipe of the condenser at the top of the xylene recovery tower. It adopts an electric three-way valve structure and can accurately adjust the ratio of reflux liquid to product liquid. The reflux ratio control accuracy is ±0.1.

[0021] Please see Figure 1-3 The exhaust gas treatment unit includes an exhaust gas absorption tower, a refrigeration unit, and a circulating pump. The exhaust gas absorption tower is a packed tower with a height of 8-12m and a diameter of 0.5-1m, filled with polypropylene stepped ring packing. Xylene at -10℃ is sprayed from the top of the tower. The refrigeration unit is a screw chiller with a cooling capacity of 10-20kW to ensure that the temperature of the spray liquid is stable between -12 and -8℃. The circulating pump has a flow rate of 8-15m³ / h, which transports the xylene at the bottom of the absorption tower to the refrigeration unit for cooling and recycling. The top of the exhaust gas absorption tower is equipped with a demister made of polytetrafluoroethylene. The exhaust gas after absorption is tested by an online VOCs detector and meets the standard (concentration ≤50mg / m³) before being discharged.

[0022] Please see Figure 1-3The xylene feed buffer tank is equipped with 4-6 baffles, which are evenly distributed along the inner wall of the tank and are 1 / 2-2 / 3 of the tank height. The reboiler steam inlet pipe is equipped with a condensate recovery device, including a steam trap, a condensate tank and a pressurizing pump, which can recover the high-temperature condensate with a temperature ≥100℃ generated by the reboiler to the boiler room for reuse, with a water saving rate of 20-30%.

[0023] Please see Figure 1-3 The system acquires real-time data on the density of the bottom liquid and the concentration of the polymer through an online monitoring unit. When the online density at the paint circulation pump outlet reaches 915 kg / m³ (corresponding to a concentration of 45-50%), the automated control unit automatically opens the regulating valve at the paint circulation pump outlet, delivering qualified paint to the paint storage tank in the tank area. During the delivery process, the xylene recovery system maintains continuous pumping and distillation without the need for shutdown and cooling. When the online density detects a concentration below 45%, the system automatically closes the regulating valve to the tank area, achieving continuous xylene recovery and continuous delivery of qualified paint. Compared to traditional processes, steam consumption is reduced by 15-20%, and the purity of the xylene product at the top of the tower is ≥99.5%. Working principle: The working principle of this continuous xylene recovery system for vinyl acetylene production is as follows: The raw material pretreatment unit receives xylene from the vinyl acetylene absorption process. After stirring in the feed buffer tank to promote byproduct polymerization, preheating by the preheater, and impurity removal by the filter, it is sent to the xylene recovery tower of the vacuum distillation unit. Under the negative pressure environment maintained by the vacuum unit, the reboiler heats the material in the tower bottom to generate steam, which is then separated from part of the reflux liquid condensed in the top condenser within the tower through mass transfer. The qualified xylene from the top of the tower enters the material conveying unit for recycling. The online monitoring unit obtains the polymer parameters in the tower bottom in real time through density sensors and concentration detectors, and transmits the data to the automation control unit. When the polymer concentration reaches 45-50%, the PLC control cabinet automatically opens the conveying valve to send it to the paint storage tank. When the concentration is below 45%, the valve is automatically closed, achieving continuous distillation without shutdown. The tail gas generated during the distillation process is purified by spraying with frozen xylene in the tail gas treatment unit and then discharged in compliance with standards. The entire system achieves continuous xylene recovery and stable polymer output through the coordinated and automated control of each unit.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0025] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A continuous recovery system for the production of xylene from vinylacetylene, characterized in that: It includes a raw material pretreatment unit, a vacuum distillation unit, an online monitoring unit, an automated control unit, a material conveying unit, and a tail gas treatment unit. Each unit is connected in sequence through pipelines and control lines to form a closed-loop system.

2. The continuous recovery system for vinyl acetylene production according to claim 1, characterized in that: The online monitoring unit includes a density sensor, a concentration detector, and temperature and pressure transmitters. The density sensor is installed on the outlet pipe of the paint circulation pump and uses a differential pressure density meter with a measurement range of 800-1000 kg / m³ and an accuracy of ±0.5 kg / m³. The concentration detector is a near-infrared online analyzer installed on the bottom discharge pipe of the tower, with a measurement range of 0-100% and an accuracy of ±1%, which cross-validates the data from the density sensor. The temperature and pressure transmitters are installed at the top of the recovery tower, the bottom of the tower, and the inlet and outlet of the reboiler, respectively. They are explosion-proof and have a measurement temperature range of 0-200℃ and a pressure range of -0.1 to 0 MPa, with a data sampling frequency of 1 time / second. Both the density sensor and the concentration detector are equipped with dual redundant probes. When one probe fails, the system automatically switches to the backup probe and triggers an alarm.

3. The continuous recovery system for vinyl acetylene production according to claim 1, characterized in that: The automated control unit includes a DCS control system, a PLC control cabinet, and a human-machine interface. The DCS control system adopts a redundant design and includes a data acquisition module, a logic control module, and an alarm module. It can receive real-time data from the online monitoring unit and output control signals according to preset logic. The PLC control cabinet is equipped with relays, contactors, and safety interlock devices to control the start, stop, and opening of the paint circulation pump, steam regulating valve, and reflux valve with a response time of ≤0.5 seconds. The human-machine interface is a 19-inch touch screen that can display system flowcharts, real-time parameters, historical trends, and alarm information, and supports manual / automatic mode switching.

4. A continuous recovery system for vinyl acetylene production of xylene according to claim 1, characterized in that: The material conveying unit includes a xylene product tank, a paint storage tank, a conveying pump, and a valve assembly. The xylene product tank is a horizontal storage tank with a volume of 5-10 m³, equipped with a level gauge and a breather valve, and the bottom of the tank is insulated. The paint storage tank is a vertical storage tank with a volume of 10-20 m³, made of Q235B carbon steel, and the inner wall is treated with anti-corrosion. The conveying pump is a magnetically driven centrifugal pump with a flow rate of 5-10 m³ / h and a head of 20-30 m. The valve assembly includes a pneumatic regulating valve, a shut-off valve, and a check valve. The pneumatic regulating valve has a response time of ≤1 second and can automatically open and close according to the signal from the automation control unit.

5. A continuous recovery system for vinyl acetylene production of xylene according to claim 1, characterized in that: The exhaust gas treatment unit includes an exhaust gas absorption tower, a refrigeration unit, and a circulating pump. The exhaust gas absorption tower is a packed tower with a height of 8-12m and a diameter of 0.5-1m, filled with polypropylene stepped ring packing. The top of the tower is sprayed with xylene at -10℃. The refrigeration unit is a screw chiller with a cooling capacity of 10-20kW to ensure that the temperature of the spray liquid is stable between -12 and -8℃. The circulating pump has a flow rate of 8-15m³ / h, which transports the xylene at the bottom of the absorption tower to the refrigeration unit for cooling and recycling.

6. A continuous recovery system for vinyl acetylene production of xylene according to claim 2, characterized in that: The xylene feed buffer tank in the material conveying unit is equipped with 4-6 baffles, which are evenly distributed along the inner wall of the tank and are 1 / 2-2 / 3 of the tank height. The reboiler steam inlet pipe is equipped with a condensate recovery device, including a steam trap, a condensate tank and a pressurizing pump, which can recover the high-temperature condensate with a temperature ≥100℃ generated by the reboiler to the boiler room for reuse, with a water saving rate of 20-30%.

7. A continuous recovery system for vinyl acetylene production of xylene according to claim 1, characterized in that: The system acquires real-time data on the density of the bottom liquid and the concentration of polymer through an online monitoring unit. When the online density at the outlet of the paint circulation pump reaches 915 kg / m³, the automatic control unit automatically opens the regulating valve at the outlet of the paint circulation pump to deliver qualified paint to the paint storage tank in the tank area. During the delivery process, the xylene recovery system maintains continuous pumping and distillation without the need to stop the system for cooling.

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