A dichloroethane recovery apparatus

Abstract

This application discloses a dichloroethane recovery device, which includes a pretreatment unit, an adsorption unit, a desorption unit, a condensation recovery unit, an oil-water separator, and a tail gas treatment unit. The pretreatment unit removes droplets and particulate impurities from the waste gas using a demister and a filter. The adsorption unit employs multiple parallel adsorption tanks with built-in hydrophobic resin adsorption beds to achieve efficient adsorption of dichloroethane. The desorption unit uses steam generated by a steam generator to desorb the saturated adsorption bed. The desorbed mixed steam is liquefied by the condensation recovery unit and then enters the oil-water separator for automatic separation and recovery of dichloroethane and water. Finally, the tail gas undergoes deep purification in an activated carbon adsorption box before being discharged in compliance with standards. This invention features high integration and automation, effectively solving the problems of low recovery efficiency and cumbersome operation in existing technologies. It is particularly suitable for the purification and resource recovery of low-to-medium concentration dichloroethane waste gas.

Description

Technical Field

[0001] This application relates to the field of industrial waste gas treatment technology, and in particular to a dichloroethane recovery device. Background Technology

[0002] Dichloroethane is an important organic chlorine solvent and chemical raw material, widely used in the chemical, pharmaceutical, and electronics industries. Its production and use generate large amounts of industrial waste gas containing dichloroethane. Dichloroethane poses significant hazards to human health and the environment, and is classified as a toxic air pollutant and a potential carcinogen; therefore, effective treatment is essential.

[0003] Currently, the main methods for treating dichloroethane waste gas include thermal combustion, catalytic combustion, absorption, and adsorption. Thermal combustion and catalytic combustion are suitable for high-concentration waste gases, but they have high energy consumption and directly decompose valuable solvents, resulting in resource waste. Absorption methods suffer from secondary pollution of the absorbent and high treatment costs. Adsorption, especially activated carbon adsorption, is a commonly used technology for treating low- to medium-concentration organic waste gases, but it has many limitations when used to recover dichloroethane: the adsorption capacity of activated carbon decreases significantly after adsorbing moisture (i.e., it is not moisture-resistant); drying the activated carbon bed after steam desorption is time-consuming and energy-intensive; and activated carbon has a low ignition point, posing certain safety hazards during the exothermic adsorption process.

[0004] Therefore, the industry has begun to use hydrophobic resins as adsorbent materials. Hydrophobic resins have a much lower adsorption capacity for water vapor than activated carbon, making them more suitable for adsorbing organic matter in humid environments. They also possess high mechanical strength, are non-flammable, and have a long service life. However, existing resin-based adsorption recovery devices often suffer from low system integration and weak pretreatment processes, leading to easy clogging of the resin bed by particulate matter or contamination by droplets. Furthermore, valve switching relies on manual operation, making it cumbersome and prone to errors. To address these issues, a dichloroethane recovery device is provided. Utility Model Content

[0005] This application provides a dichloroethane recovery device that solves the problems mentioned in the background art.

[0006] This application provides a dichloroethane recovery device, including: a pretreatment unit, an adsorption unit, a desorption unit, a condensation recovery unit, an oil-water separator, and a tail gas treatment unit. The pretreatment unit includes an inlet pipe and a demister and a filter arranged sequentially from front to back on the inlet pipe. The demister includes a demister box, a demister box cover on top of the demister box, and replaceable demister cotton inside the demister box. The filter includes a filter box, a filter screen inclined inside the filter box, a waste discharge pipe at the bottom of the filter box, and a waste discharge valve on the waste discharge pipe. The top of the filtration unit is connected to a cleaning device, which includes an air duct connected to the filter box, an air valve on the air duct, and a fan at the air duct inlet. The adsorption unit includes a gas distribution mechanism, multiple air outlet valves on the gas distribution mechanism, and air supply pipes connected to the air supply valves. Each air supply pipe is connected to an adsorption unit at its end. The adsorption unit includes an adsorption tank, a hydrophobic resin adsorption bed in the middle cavity of the adsorption tank, a liquid distributor in the upper cavity, a gas distributor in the lower cavity, an exhaust pipe on the side wall of the adsorption tank, and an exhaust valve on the exhaust pipe. The desorption unit includes a steam generator on the ground, a steam main pipe connected to the steam generator, steam branch pipes connected to the end of the steam main pipe, and steam valves on each steam branch pipe. The condensation recovery unit includes an inclined condenser pipe, a condensation jacket wrapped around the side wall of the condenser pipe, a refrigerant inlet pipe and a refrigerant outlet pipe on the condensation jacket, a recovery main pipe connected to the inlet of the condenser pipe, and multiple recovery valves connected to the inlet of the recovery main pipe. The oil-water separator includes an oil-water separation device and a collection tank. The oil-water separation device includes an oil-water separation tank, an observation window on the side wall of the oil-water separation tank, a discharge pipe connected to the bottom of the oil-water separation tank, a drain pipe connected to the side wall of the discharge pipe, a drain valve on the drain pipe, and a discharge valve on the discharge pipe. The collection tank is connected to the end of the discharge pipe. The exhaust gas treatment unit includes an activated carbon adsorption box and an exhaust pipe connected to the output end of the activated carbon adsorption box. The pretreatment unit is connected to the adsorption unit, and the end of the inlet pipe is connected to the input end of the gas distribution mechanism. The adsorption unit is connected to the exhaust gas treatment unit, and the ends of multiple exhaust pipes are all connected to the activated carbon adsorption box. The desorption unit is connected to the adsorption unit, and multiple water vapor distribution pipes are respectively connected to the connecting pipes at the top of the corresponding liquid distributors. The condensation recovery unit is connected to the adsorption unit, and multiple recovery distribution pipes are respectively connected to the pipes at the bottom of the corresponding adsorption tanks. The condensation recovery unit is connected to the oil-water separator, and the output end of the condenser pipe is connected to the top of the oil-water separation tank.

[0007] Furthermore, a temperature sensor is provided on the sidewall of the hydrophobic resin adsorption bed.

[0008] Furthermore, the activated carbon adsorption box is equipped with multiple layers of activated carbon adsorption plates.

[0009] Furthermore, the observation window is a transparent observation window.

[0010] Furthermore, the liquid distributor has several nozzles at the bottom, and the gas distributor has several air holes in the middle.

[0011] Furthermore, the intake valve, fan, air valve, air delivery valve, exhaust valve, steam generator, steam valve, recovery valve, drain valve, temperature sensor, and discharge valve are electrically connected to the same PLC controller.

[0012] As can be seen from the above technical solutions, this application provides a dichloroethane recovery device, wherein the outlet of the pretreatment unit is connected to the inlet of the adsorption unit, the purified gas outlet of the adsorption unit is connected to the inlet of the tail gas treatment unit, the outlet of the desorption unit is connected to the desorption inlet of the adsorption unit, the desorption outlet of the adsorption unit is connected to the inlet of the condensation recovery unit, and the outlet of the condensation recovery unit is connected to the inlet of the oil-water separator. The pretreatment unit includes an air inlet pipe with an air inlet valve. A demister and a filter are arranged sequentially along the airflow direction. The demister consists of a demister box, a box cover, and internal demister cotton. The demister box cover can be opened to replace the demister cotton, ensuring the effectiveness of removing water vapor and removing water vapor from the exhaust gas. The filter consists of a filter box, an inclined filter screen, a bottom discharge pipe, and a discharge valve to remove particulate matter from the exhaust gas. To ensure the filtration effect of the filter screen; A cleaning device is connected to the top of the filter box. The device consists of a fan, air duct and air valve. It can periodically blow air into the filter box to back-clean the filter screen, so that the particles adhering to the filter screen mesh can be removed from the filter screen to ensure the filtration efficiency and filtration effect of the filter screen. The adsorption unit is the core component, employing multiple adsorption tanks connected in parallel. Each tank is filled with a hydrophobic resin adsorption bed, and a liquid distributor is located at the top and a gas distributor at the bottom. This achieves uniform distribution of waste gas and full utilization of the adsorbent. By switching valves, multiple adsorption tanks can be used alternately for adsorption and desorption, ensuring continuous operation.

[0013] The desorption unit uses a ground-mounted steam generator, which precisely introduces steam into the liquid distributor at the top of the adsorption tank to be desorbed through the main pipe and branch pipes, thereby desorbing the saturated adsorbent. The condensation recovery unit uses a jacketed condenser, through which refrigerant is introduced to condense the desorbed high-temperature mixed vapor into a liquid state; The oil-water separator uses a separation tank with an observation window. It utilizes the density difference between dichloroethane and water to create stratification, and achieves automatic separation and recovery through parallel drain valves and discharge valves. After the lower layer of dichloroethane flows into the collection tank, the upper layer of water is discharged.

[0014] The exhaust gas treatment unit uses an activated carbon adsorption box to deeply purify the final exhaust gas, ensuring that emissions meet standards. The core components of the device, such as valves, fans, steam generators, and temperature sensors, are all centrally controlled by a PLC controller, realizing the automated operation of the entire adsorption-desorption-recovery process.

[0015] In summary, the beneficial effects of this application are as follows: 1. It solves the problem of decreased adsorbent efficiency in humid exhaust gas environments, and utilizes hydrophobic resin to ensure the stability and high capacity of the adsorption process.

[0016] 2. Through parallel connection of multiple tanks and intelligent control by PLC controller, true continuous automated operation is achieved, improving processing efficiency.

[0017] 3. Enhanced pretreatment and final exhaust gas treatment ensured the long-term stable operation of the entire system and compliance of exhaust gas emissions.

[0018] 4. The recovered dichloroethane has a high purity, resulting in significant economic benefits and achieving a combination of pollution control and resource recovery. Attached Figure Description

[0019] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the implementation examples will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of this application.

[0021] Figure 2 This is a cross-sectional structural diagram of the demisting device of this application.

[0022] Figure 3 This is a cross-sectional structural diagram of the filtration device of this application.

[0023] Figure 4 This is a cross-sectional structural diagram of the adsorption device of this application.

[0024] Figure 5 This is a schematic diagram of the oil-water separator structure of this application.

[0025] Figure 6 This is a schematic diagram of the PLC controller structure in this application.

[0026] Illustration: Among them, 1-inlet pipe, 2-inlet valve, 3-demisting device, 31-demisting box, 32-demisting box cover, 33-demisting cotton, 4-filtering device, 41-filter box, 42-filter screen, 43-exhaust pipe, 44-exhaust valve, 5-fan, 6-air duct, 7-air valve, 8-gas distribution mechanism, 9-gas delivery valve, 10-gas delivery pipe, 11-adsorption device, 111-adsorption tank, 112-hydrophobic resin adsorption bed, 113-liquid distributor, 114-nozzle, 115-gas distributor, 116-vent, 12-exhaust pipe, 13- 14-Exhaust valve, 15-Steam generator, 16-Steam main pipe, 17-Steam branch pipe, 18-Steam valve, 19-Recovery branch pipe, 20-Recovery valve, 21-Recovery main pipe, 22-Condenser pipe, 23-Condenser jacket, 24-Refrigerant inlet pipe, 25-Refrigerant outlet pipe, 26-Oil-water separator, 261-Oil-water separator tank, 262-Observation window, 263-Discharge pipe, 264-Drain pipe, 265-Drain valve, 266-Discharge valve, 27-Collection tank, 28-Activated carbon adsorption box, 29-PLC controller. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0028] From the above technical solutions, it can be seen that: Example 1: See Figures 1-6 .

[0029] The object of treatment in this embodiment is waste gas containing dichloroethane generated by a chemical plant. The waste gas flow rate is 3000 Nm³ / h, the concentration is 1500 mg / m³, and the waste gas contains a small amount of water mist and dust.

[0030] The device is equipped with three adsorption tanks 111, namely adsorption tank 111A, adsorption tank 111B and adsorption tank 111C. Each tank is filled with a hydrophobic resin adsorption bed 112 (such as polystyrene-based adsorption resin) of about 1.5 cubic meters. The filter screen 42 is made of 60-mesh stainless steel wire mesh. The defogging cotton 33 is made of PP material. The oil-water separator 261 has a volume of 200L. The rated evaporation capacity of the steam generator 15 is 150kg / h.

[0031] During operation, the exhaust gas containing dichloroethane enters the pretreatment unit through the inlet pipe 1. First, it passes through the demister 3, where the droplets are captured by the demister cotton 33. Then, the gas enters the filter 4, where particulate dust is intercepted by the inclined filter screen 42 and slides to the bottom. The discharge valve 44 is opened periodically to discharge the dust. The pretreated clean waste gas enters the gas distribution mechanism 8. Assuming that the current PLC controller 29 sets the state of the three adsorption tanks 111 as follows: adsorption tanks 111A and 111B are in the adsorption state, and adsorption tank 111C is in the desorption or standby state, at this time, the gas supply valves 9A and 9B and the exhaust valves 13A and 13B are open, and the gas supply valve 9C and the exhaust valve 13C are closed. The waste gas enters the lower chamber of adsorption tanks 111A and 111B respectively, and passes evenly through the hydrophobic resin adsorption bed 112 via the gas distributor 115. The dichloroethane in the bed is selectively adsorbed and retained. The purified gas flows from the upper chamber through the exhaust pipes 12A and 12B into the activated carbon adsorption box 28 for final purification. After meeting the standards, the gas is discharged through the gas outlet pipe 14.

[0032] When the hydrophobic resin adsorption bed 112 in adsorption tank 111A is close to saturation (determined by a preset time or bed temperature sensor signal), and the hydrophobic resin adsorption beds 112 in adsorption tanks 111B and 111C are not saturated and operating normally, the PLC controller 29 starts the desorption program. Gas supply valves 9B and 9C and exhaust valves 13B and 13C remain open, gas supply valve 9A and exhaust valve 13A are closed, steam valves 18B and 18C and recovery valves 20B and 20C remain closed, and steam valve 18A and recovery valve 20A are opened. Steam generated by the steam generator 15 enters through steam distribution pipe 17A. The liquid distributor 113 at the top of the adsorption tank 111A sprays the liquid evenly onto the hydrophobic resin adsorption bed 112 through the nozzle 114, desorbing the adsorbed dichloroethane and forming a high-temperature mixture of dichloroethane and water vapor. The mixture is discharged from the bottom of the adsorption tank 111A and enters the condenser 22 through the recovery branch pipe 19A and the recovery main pipe 21. The refrigerant (such as cooling water) enters the condenser jacket 23 from the refrigerant inlet pipe 24 and flows out from the refrigerant outlet pipe 25. During this period, it exchanges heat with the mixed vapor in the pipe and condenses it into a liquid mixture of dichloroethane and water. The condensate flows into the oil-water separator 261 by gravity. After standing in the oil-water separator 261 for a period of time, due to the density difference, liquid dichloroethane (density greater than water) sinks to the bottom layer, while water floats to the top layer. The operator can observe the liquid level stratification through the observation window 262 and control the valves via the PLC controller 29: first, open the discharge valve 266 to discharge the lower layer of dichloroethane into the collection tank 27 for recovery; then, when the water level drops to near the discharge valve 266, close the discharge valve 266 and open the drain valve 265. At this point, a complete desorption-recovery cycle is completed, and the adsorption tank 111A enters the drying and cooling stage, preparing for the next adsorption cycle.

[0033] Preferably, the PLC controller 29 will cycle through the working states of the three adsorption tanks 111 according to a preset program to achieve continuous and stable operation of the device.

[0034] Preferably, the PLC controller 29 initiates a timed command to start the fan 5 and open the air valve 7 to backflush and clean the filter screen 42, thereby ensuring the filtration effect of the filter screen 42.

[0035] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope of this application is indicated by the claims.

[0036] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The embodiments of this application described above do not constitute a limitation on the scope of protection of this application.

Claims

1. A dichloroethane recovery device, comprising: A pretreatment unit, an adsorption unit, a desorption unit, a condensation recovery unit, an oil-water separator, and a tail gas treatment unit are characterized in that: the pretreatment unit includes an air inlet pipe (1) and an air inlet valve (2), a demister (3), and a filter (4) arranged sequentially from front to back on the air inlet pipe (1); the demister (3) includes a demister box (31), a demister box cover (32) on top of the demister box (31), and replaceable demister cotton (33) inside the demister box (31); the filter (4) includes a filter box (41) and a filter element inclined inside the filter box (41). The filter device (4) includes a filter screen (42), a waste discharge pipe (43) at the bottom of the filter box (41), and a waste discharge valve (44) on the waste discharge pipe (43); the top of the filter device (4) is connected to a cleaning device, which includes an air duct (6) connected to the filter box (41), an air valve (7) on the air duct (6), and a fan (5) at the input end of the air duct (6); the adsorption unit includes a gas distribution mechanism (8), a gas supply valve (9) with multiple gas outlets on the gas distribution mechanism (8), and a gas supply pipe (10) connected to the gas supply valve (9), each of the above... Each gas delivery pipe (10) is connected to an adsorption device (11) at its end. The adsorption device (11) includes an adsorption tank (111), a hydrophobic resin adsorption bed (112) in the middle cavity of the adsorption tank (111), a liquid distributor (113) in the upper cavity, a gas distributor (115) in the lower cavity, an exhaust pipe (12) on the side wall of the adsorption tank (111), and an exhaust valve (13) on the exhaust pipe (12). The desorption unit includes a water vapor generator (15) located on the ground, a water vapor main pipe (16) connected to the water vapor generator (15), and a water vapor main pipe (16) connected to the water vapor generator (15). The steam main (16) has a steam branch pipe (17) at the end and a steam valve (18) on each of the steam branch pipes (17); the condensation recovery unit includes an inclined condenser pipe (22), a condensation jacket (23) wrapped around the side wall of the condenser pipe (22), a refrigerant inlet pipe (24) and a refrigerant outlet pipe (25) on the condensation jacket (23), a recovery main pipe (21) connected to the input end of the condenser pipe (22), and a plurality of recovery branch pipes (19) connected to the input end of the recovery main pipe (21) and a recovery valve (20) on each of the recovery branch pipes (19);The oil-water separator includes an oil-water separation device (26) and a collection tank (27). The oil-water separation device (26) includes an oil-water separation tank (261), an observation window (262) on the side wall of the oil-water separation tank (261), a discharge pipe (263) connected to the bottom of the oil-water separation tank (261), a drain pipe (264) connected to the side wall of the discharge pipe (263), a drain valve (265) on the drain pipe (264), and a discharge valve (266) on the discharge pipe (263). The collection tank (27) is connected to the end of the discharge pipe (263). The exhaust gas treatment unit includes an activated carbon adsorption box (28) and an exhaust pipe (14) connected to the output end of the activated carbon adsorption box (28). The pretreatment unit is connected to the adsorption unit, and the end of the inlet pipe (1) is connected to the input end of the gas distribution mechanism (8); the adsorption unit is connected to the tail gas treatment unit, and the ends of multiple exhaust pipes (12) are all connected to the activated carbon adsorption box (28); the desorption unit is connected to the adsorption unit, and multiple water vapor distribution pipes (17) are respectively connected to the connecting pipes at the top of the corresponding liquid distributor (113); the condensation recovery unit is connected to the adsorption unit, and multiple recovery distribution pipes (19) are respectively connected to the pipes at the bottom of the corresponding adsorption tank (111); the condensation recovery unit is connected to the oil-water separator, and the output end of the condenser pipe (22) is connected to the top of the oil-water separator tank (261).

2. The dichloroethane recovery device according to claim 1, characterized in that, A temperature sensor is provided on the side wall of the hydrophobic resin adsorption bed (112).

3. The dichloroethane recovery device according to claim 1, characterized in that, The activated carbon adsorption box (28) is equipped with multiple layers of activated carbon adsorption plates.

4. The dichloroethane recovery device according to claim 1, characterized in that, The observation window (262) is a transparent observation window.

5. A dichloroethane recovery device according to claim 1, characterized in that, The liquid distributor (113) has several nozzles (114) at its bottom, and the gas distributor (115) has several air holes (116) in the middle.

6. A dichloroethane recovery device according to claim 2, characterized in that, The air inlet valve (2), the fan (5), the air valve (7), the air delivery valve (9), the exhaust valve (13), the steam generator (15), the steam valve (18), the recovery valve (20), the drain valve (265), the temperature sensor, and the discharge valve (266) are electrically connected to the same PLC controller (29).

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