Disclosure of Invention
The invention aims to provide a white oil refining system for recycling diaphragm extract of a lithium battery.
The invention aims to provide a refining method for recycling the diaphragm extract of the lithium battery.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
According to a first aspect of the embodiment of the invention, a white oil refining system for recycling lithium battery diaphragm extract is provided, which comprises a kettle type reboiler, a tower top condenser, a vacuum buffer tank, a water ring vacuum pump, a gas-liquid separation tank, an oil separation tank and an aeration tank, wherein,
The feed inlet of the kettle-type reboiler is connected with an upstream pipeline, the gas phase discharge port is connected with the feed inlet of the tower top condenser, the liquid phase discharge port is connected with a downstream pipeline, the gas distributor is connected with the upstream pipeline, and the tower top reflux port is connected with the liquid phase discharge port of the tower top condenser;
The gas phase discharge port of the tower top condenser is connected with the feed port of the vacuum buffer tank, the discharge port of the vacuum buffer tank is connected with the air suction port of the water ring vacuum pump, the output port of the water ring vacuum pump is connected with the feed port of the gas-liquid separation tank, and the water supplementing port is connected with the liquid phase discharge port of the aeration tank and the upstream water supplementing pipeline;
The gas phase discharge port of the gas-liquid separation tank is connected with the downstream VOC adsorption device, the liquid phase discharge port is connected with the feed inlet of the oil separation tank, the discharge port of the oil separation tank is connected with the feed inlet of the aeration tank, and the gas phase discharge port of the aeration tank is connected with the downstream VOC adsorption device.
The water ring vacuum pump is characterized in that a top pressure sensor is arranged at the top of the inside of the kettle type reboiler, a controller of the water ring vacuum pump is connected with the top pressure sensor, and the running rotating speed of the water ring vacuum pump is controlled according to the measurement data of the top pressure sensor so as to maintain the internal air pressure of the kettle type reboiler and the air outlet quantity of a gas phase discharge port.
Wherein, preferably, the white oil refining system also comprises a separating tank condenser and a diameter expanding pipe, wherein,
The gas phase discharge port of the expanding pipe is connected with a downstream VOC adsorption device, and the liquid phase discharge port is connected with a downstream condensate recovery pipeline.
Wherein, preferably, the white oil refining system also comprises a water ring pump condenser, wherein,
The feed inlet of the water ring pump condenser is connected with the liquid phase discharge port of the aeration tank, and the discharge port is connected with the water supplementing port of the water ring vacuum pump.
According to a second aspect of embodiments of the present invention, there is provided a refining method for lithium battery separator extract recovery, comprising the steps of:
step S1, heating crude white oil to a design temperature by using a kettle type reboiler, reducing the internal pressure of the kettle type reboiler to the design pressure by using a water ring vacuum pump, and distributing nitrogen into the crude white oil by using a gas distributor of the kettle type reboiler so as to carry out reduced pressure rectification and nitrogen gas on the crude white oil, so that the crude white oil is separated into refined white oil and tail gas;
S2, condensing the tail gas to a design temperature by utilizing the tower top condenser so as to separate the tail gas into condensate and noncondensable gas;
S3, reducing pressure fluctuation of the kettle type reboiler and the tower top condenser by utilizing the vacuum buffer tank;
Step S4, utilizing the water ring vacuum pump to provide power for gas-phase materials in the kettle type reboiler, the tower top condenser and the vacuum buffer tank to enable the gas-phase materials to move in a pipeline and equipment, utilizing the water ring vacuum pump to enable the white oil component to be mixed into small liquid drops in working solution, and separating the white oil component in noncondensable gas from the gas-phase components of dichloromethane and nitrogen to form mixed gas-liquid;
s5, utilizing the gas-liquid separation tank to separate the mixed gas and liquid into mixed gas and mixed liquid, and utilizing downstream equipment to recycle and treat the mixed gas;
S6, separating a white oil component in the mixed solution by utilizing the oil separation groove to obtain oil separation liquid;
and S7, heating and aerating oil-separating liquid by using the aeration tank, separating out gaseous methylene dichloride to form aeration gas and aeration liquid, recycling and treating the aeration gas by using downstream equipment, and providing the aeration liquid serving as working liquid to the water ring vacuum pump.
Preferably, the controller of the water ring vacuum pump is used for controlling the rotating speed of the water ring vacuum pump according to the detection data of the top pressure sensor in the kettle-type reboiler.
Wherein, the heating temperature of the crude white oil in the kettle-type reboiler is preferably not lower than 140 â, and the temperature of the nitrogen input into the kettle-type reboiler is not lower than 140 â.
Wherein, the mixed gas is cooled to the design temperature by utilizing a separator tank condenser, the mixed gas is separated into separated non-condensable gas and separated condensate by utilizing a diameter-expanding pipe, and the separated non-condensable gas and the separated condensate are respectively recovered by utilizing downstream equipment.
Preferably, the water ring pump condenser is used for cooling the aeration liquid to the design temperature, and then the aeration liquid is provided for the water ring vacuum pump to serve as the working liquid.
Compared with the prior art, the method effectively solves the problem of high residual quantity of dichloromethane in the prior art by adopting a combined process of vacuum rectification and nitrogen stripping. The white oil refining system adopts equipment such as a kettle-type reboiler, a tower top condenser, a vacuum buffer tank, a water ring vacuum pump, a gas-liquid separation tank, an oil separation tank, an aeration tank and the like, so that the high-efficiency refining of crude white oil is realized, the mass concentration of dichloromethane in refined white oil is not higher than 30ppm, and the recycling requirement of workshops is met. Meanwhile, the non-condensable gas tail gas at the top of the tower is treated and then is merged into a gas-phase VOC recovery device in a factory, and the gas-phase VOC recovery device further recovers dichloromethane and then is discharged after reaching standards, so that the environmental pollution is effectively reduced. In addition, the use of the water ring vacuum pump not only improves the vacuum degree of the system, but also breaks up white oil into small liquid drops through the impeller with high shearing force, thereby facilitating subsequent separation and recovery and prolonging the service life of the VOC adsorption device.
DetailedâDescription
The technical contents of the present invention will be described in detail with reference to the accompanying drawings and specific examples.
The technical concept of the embodiment of the invention is that the methylene dichloride is separated from the crude white oil by utilizing the great difference of the relative volatilities of the methylene dichloride and the white oil under the pressure-reducing working condition. Nitrogen Tilly uses the inertia and stability of nitrogen to effectively carry and separate the methylene dichloride in the crude white oil by adjusting the temperature, the pressure and the flow. In the process, nitrogen is used as a carrier and also plays a role in protecting and preventing oxidation discoloration of white oil.
The first embodiment of the invention provides a white oil refining system for recovering diaphragm extract of a lithium battery, which comprises a kettle-type reboiler 1, a tower top condenser 2, a vacuum buffer tank 3, a water ring vacuum pump 4, a gas-liquid separation tank 5, an oil separation tank 6 and an aeration tank 7. Wherein, the kettle reboiler 1 is disclosed in ZL 202321891481.0 patent which is already authorized by the applicant, and is not repeated here
As shown in fig. 1, the kettle-type reboiler 1 is a refining device for refining crude white oil into refined white oil, and comprises heating and nitrogen stripping devices. The feed port 11 (liquid distributor) of the kettle reboiler 1 is connected to an upstream line for feeding crude white oil. The gas phase discharge port 12 is connected with a feed port 21 of the tower top condenser 2 and is used for discharging tail gas obtained by rectifying crude white oil. The liquid phase discharging port 13 is connected with a downstream pipeline and is used for discharging refined white oil obtained by rectifying crude white oil. The gas distributor 14 is connected with an upstream pipeline and is used for inputting nitrogen into the kettle reboiler 1 and stripping the crude white oil. The overhead reflux port 15 is connected to the liquid phase outlet 23 of the overhead condenser 2 for providing overhead reflux. The top of the inside of the kettle reboiler 1 is provided with a top pressure sensor 16. The heat exchange tube bundle 17 of the kettle-type reboiler 1 is connected with an external steam pipeline and is used for providing heat energy for rectifying crude white oil.
The tower top condenser 2 is a gas condensing device and comprises a cooling pipeline and a material pipeline. The feed inlet 21 of the tower top condenser 2 is connected with the gas phase discharge port 12 of the kettle type reboiler 1, the liquid phase discharge port 23 is connected with the tower top reflux port 15 of the kettle type reboiler 1, and the gas phase discharge port 22 is connected with the feed inlet 31 of the vacuum buffer tank 3. Wherein the feed inlet 21, the liquid phase discharge outlet 23 and the gas phase discharge outlet 22 of the tower top condenser 2 are different ports of a material pipeline. The cooling line of the overhead condenser 2 is connected to a cooling medium line, such as a cold water line.
The vacuum buffer tank 3 is a gas buffer device, and can reduce pipeline pressure fluctuation in the white oil refining system. The feed port 31 of the vacuum buffer tank 3 is connected with the gas phase discharge port 22 of the tower top condenser 2, and the discharge port 32 is connected with the air suction port 41 of the water ring vacuum pump 4.
The water ring vacuum pump 4 is air pump equipment, can generate vacuum pressure for the white oil refining system, and provides pipeline conveying power. The air suction port 41 of the water ring vacuum pump 4 is connected with the discharge port 32 of the vacuum buffer tank 3, the output port 42 is connected with the feed port 51 of the gas-liquid separation tank 5, and the water supplementing port 43 is connected with the liquid phase discharge port 73 of the aeration tank 7 and the upstream water supplementing pipeline. Preferably, the controller 44 of the water ring vacuum pump 4 is connected to the top pressure sensor 16 of the kettle reboiler 1, and controls the operation rotation speed (power) of the water ring vacuum pump 4 according to the measurement data of the top pressure sensor 16, so as to maintain the internal air pressure of the kettle reboiler 1 (make it stable at the design pressure), and the gas outlet amount of the gas phase outlet 12. Optionally, the white oil refining system comprises a plurality of water ring vacuum pumps 4, each water ring vacuum pump 4 being connected in parallel.
The gas-liquid separation tank 5 is a separation device for gas phase and liquid phase components. The feed inlet 51 of the gas-liquid separation tank 5 is connected with the output port 42 of the water ring vacuum pump 4, the gas phase discharge port 52 is connected with the downstream VOC adsorption device, and the liquid phase discharge port 53 is connected with the feed inlet 61 of the oil separation tank 6.
The oil separator 6 is a liquid separation device capable of adsorbing and separating white oil components from a liquid. The feed inlet 61 of the oil separation tank 6 is connected with the liquid phase discharge outlet 53 of the gas-liquid separation tank 5, and the discharge outlet 62 is connected with the feed inlet 71 of the aeration tank 7.
The aeration tank 7 is an aeration device including heating and air stripping devices, and is capable of separating volatile gases from liquid. The feed inlet 71 of aeration tank 7 connects the discharge gate 62 of oil separator 6, and the gas phase discharge gate 72 connects the downstream VOC adsorption equipment, and the liquid phase discharge gate 73 connects the moisturizing mouth 43 of water ring vacuum pump 4.
The water ring vacuum pump 4 provides a decompression vacuum environment for the kettle-type reboiler 1, so that the absolute pressure in the kettle-type reboiler 1 is maintained at 30-50 kPa, and the volatility of dichloromethane is increased. The decompression rectification mainly uses the great difference of the relative volatilities of the dichloromethane and the white oil under the decompression working condition to separate the dichloromethane from the crude white oil.
And (3) rectifying and recovering dichloromethane from the lithium battery diaphragm extract by using an upstream device through low-temperature rectification (40-50 â) to obtain crude white oil. The crude white oil enters the kettle-type reboiler 1 from the feed inlet of the kettle-type reboiler 1, is heated, the temperature is maintained at 130-150 â (preferably 140 â), and is depressurized to 30-50 kpa (vacuum), so as to increase the volatility of dichloromethane. And the nitrogen gas conveyed by an upstream pipeline is injected into the crude white oil by the gas distributor of the kettle-type reboiler 1, and is stripped along with the dichloromethane, so that the volatility of the dichloromethane is further increased. Preferably, the nitrogen temperature fed into the kettle reboiler 1 is not lower than 140 â to maintain the temperature of the crude white oil. The crude white oil is subjected to high temperature, reduced pressure rectification and nitrogen gas stripping to become essential white oil, and the essential white oil is discharged and recovered from a liquid phase discharge port of the kettle type reboiler 1. It is noted that the prior art requires that the methylene dichloride content in the refined white oil is less than or equal to 30ppm. Experiments prove that when the kettle-type reboiler operates at 140 â and 30-50 kPa, the residual quantity of dichloromethane in the essential oil can meet the index.
Nitrogen stripping mainly utilizes the inertia and stability of nitrogen, and methylene dichloride needing to be extracted and separated is effectively carried out from crude white oil by adjusting temperature, pressure and nitrogen flow. In the process, nitrogen is used as a carrier, plays a role in protecting and preventing oxidation discoloration of white oil, and has no air pollution.
Under normal pressure, the gas-liquid phase transition temperature of white oil with different labels is 250-350 â, and the gas-liquid phase transition temperature of dichloromethane is 40 â. On the one hand, in order to reduce energy consumption (economy), on the other hand, under the decompression working condition, the relative volatility of white oil and dichloromethane can be increased, separation of the white oil and the dichloromethane is facilitated, so that the best separation effect is achieved, and on the other hand, the third aspect, the tail gas pressure is ensured to be matched with the pressure of a water ring vacuum pump (the pressure in a kettle type reboiler 1 is maintained to be stable and free from fluctuation), so that the temperature of the crude white oil is heated to 130-150 â, the pressure is reduced to 30-50 kPa, and meanwhile, the dichloromethane in the crude white oil can be fully volatilized by being matched with nitrogen stripping, so that dichloromethane vapor is formed, and separation of the white oil and the dichloromethane is realized. However, white oil vapor is inevitably generated. Therefore, the tail gas discharged from the kettle reboiler 1 through the gas phase discharge port comprises methylene dichloride, white oil and nitrogen. The dichloromethane is treated by the downstream VOC adsorption device, but the white oil component in the tail gas has high boiling point and high viscosity, and the service life of the adsorption material can be reduced, so that the white oil component in the tail gas needs to be fully removed before entering the VOC adsorption device. Among them, the nitrogen component does not affect the effect of VOC adsorption and discharge, so removal is not required.
The tail gas discharged from the gas phase discharge port 12 of the kettle-type reboiler 1 enters a material pipeline of the tower top condenser 2 from a feed port 21 of the tower top condenser 2, and the tail gas is fully heat-exchanged with a cooling medium in a cooling pipeline to reduce the temperature to a design temperature, such as the condensation liquefaction temperature (40 â) of methylene dichloride. The condensate formed by condensation is discharged from a liquid phase discharge port 23 of the tower top condenser 2 and flows back into the kettle type reboiler 1 through a tower top return port 15 of the kettle type reboiler 1. The noncondensable gas formed by condensation is discharged from the gas phase discharge port 22 of the tower top condenser 2 and is input into the vacuum buffer tank 3 through the feed port 31 of the vacuum buffer tank 3. The noncondensable gas comprises dichloromethane, white oil and nitrogen.
The vacuum buffer tank 3 can reduce the pressure fluctuation of the pipeline in the white oil refining system and avoid the pipeline and the process equipment from being impacted by the gas pressure with severe change. The non-condensable gas in the vacuum buffer tank 3 is output from the discharge port 32 and is input into the water ring vacuum pump 4 through the air suction port 41 of the water ring vacuum pump 4.
The water ring vacuum pump 4 inputs the working fluid through the water supplementing port 43, inputs the non-condensable gas through the air suction port 41, and outputs the mixed gas-liquid through the output port 42. The water ring vacuum pump 4 provides power for the gas phase materials in the kettle type reboiler 1, the tower top condenser 2 and the vacuum buffer tank 3, so that the gas phase materials move in the pipeline and the equipment. The power of the water ring vacuum pump 4 comes from the variable frequency motor. The mixed gas-liquid comprises liquid phase components of water and white oil and gas phase components of dichloromethane and nitrogen. Notably, because of the impact and shearing action of the impeller of the water ring vacuum pump 4, the white oil component in the noncondensable gas is broken up into small droplets and mixed into the water, thus forming an oil-water mixture, so that the white oil which is almost insoluble in water can be completely discharged with the water flow, and deposition, floatation or adhesion hardly occurs. While the methylene chloride and nitrogen components in the non-condensable gas are water-insoluble gases, so that the white oil component can be separated in the gas-liquid separation tank 5.
The controller 44 of the water ring vacuum pump 4 is connected with the top pressure sensor 16 of the kettle-type reboiler 1, and controls the operation power of the water ring vacuum pump 4 according to the measurement data of the top pressure sensor 16 so as to control the air inflow of the air suction port 41, and further control the air pressure in the kettle-type reboiler 1 to keep stable. Notably, because of the connection relationship of the kettle reboiler 1, the overhead condenser 2, the vacuum buffer tank 3, and the water ring vacuum pump 4, the water ring vacuum pump 4 simultaneously reduces the internal air pressure of the overhead condenser 2 and the vacuum buffer tank 3, i.e., provides a vacuum environment.
The mixed gas-liquid output from the output port 42 of the water ring vacuum pump 4 is input into the gas-liquid separation tank 5 from the feed port 51 of the gas-liquid separation tank 5, and is separated into a mixed liquid and a mixed gas. Wherein the mixed gas comprises dichloromethane and nitrogen components, the mixed liquid comprises water and white oil components, and the mixed liquid possibly comprises the dichloromethane components which are not separated. The mixed gas is output from a gas phase discharge port 52 of the gas-liquid separation tank 5 and sent to a downstream VOC adsorption device for reprocessing. The mixed liquid is output from the liquid-phase discharge port 53 of the gas-liquid separation tank 5, and is input into the oil separator 6 from the feed port 61 of the oil separator 6.
The oil separating groove 6 adsorbs and separates white oil components from the mixed liquid to obtain oil separating liquid. The barrier fluid comprises water and possibly unseparated dichloromethane components. The oil-separating liquid is output from the discharge port 62 of the oil-separating tank 6 and is input into the aeration tank 7 from the feed port 71 of the aeration tank 7.
The aeration tank 7 is used for obtaining aeration gas and aeration liquid by heating the oil-separating liquid and inputting air into the oil-separating liquid for gas stripping and evaporating dichloromethane components possibly existing in the oil-separating liquid. The aeration gas is output through a gas phase discharge port 72 of the aeration tank 7 and is sent to a downstream VOC adsorption device for reprocessing. The aeration liquid is output through the liquid phase discharge port 73 of the aeration tank 7 and is input by the water supplementing port 43 of the water ring vacuum pump 4 as the working liquid of the water ring vacuum pump 4.
White oil is a mineral oil, and its main component is saturated hydrocarbon compound, and its water solubility is very low. White oil is hardly soluble in water, and thus in the gas-liquid mixture, white oil exists mainly in the form of droplets or an oil film, not dissolved in water. Therefore, the white oil adheres more to the surface of the apparatus in the form of droplets or an oil film, resulting in lower separation efficiency of the white oil in the gas-liquid separator, and difficult recovery by simple separation of the aqueous phase. The white oil has higher viscosity, especially at low temperature, poorer fluidity and easier deposition on the pipe wall. White oil has a high boiling point and high thermal stability, and generally does not undergo decomposition or chemical reaction at the operating temperature of the water ring vacuum pump. The main problem with white oils is coking at high temperatures, especially when in contact with air. However, if the temperature in the pipeline is low, the white oil may become more viscous, further exacerbating the deposition phenomenon.
In particular, the low solubility of white oils makes them difficult to recover by dissolution and cooling, more dependent on physical separation. The high boiling point of white oil means that it does not significantly vaporize in the circulating water system, and recovery efficiency may be limited by separation efficiency. The high thermal stability of white oil prevents decomposition during operation, but it is desirable to prevent coking.
The water ring vacuum pump has high shearing force impeller to make white oil sheared fully in water to form fine oil drop to mix with water to form homogeneous liquid phase component. According to the actual running condition, the proportion of water to white oil is dynamically adjusted to ensure that the particle size of oil drops is small enough.
Nitrogen is an inert gas that does not react chemically with white oil, methylene chloride or water. The kettle-type reboiler 1 is filled with nitrogen gas, so that the nitrogen gas is used as a protective gas of the white oil at high temperature, and the white oil can be prevented from being in contact with air to cause color deepening. In addition, the nitrogen can be used for stripping light component methylene dichloride in the white oil, so that the purity of the recovered white oil is ensured.
Unlike the above embodiments, the white oil refining system provided in the second embodiment of the present invention further includes a water ring pump condenser 8, a separator tank condenser 9, and an enlarged diameter pipe 1.
The water ring pump condenser 8 is a gas condensing device with a cooling pipeline and a material pipeline. Wherein the cooling line connects upstream and downstream cooling medium lines, such as cooling water lines. The feed inlet 81 (material pipeline) of the water ring pump condenser 8 is connected with the liquid phase discharge outlet 73 of the aeration tank 7, and the discharge outlet 82 is connected with the water supplementing port 43 of the water ring vacuum pump 4. The aeration liquid which is input into the material pipeline of the water ring pump condenser 8 is subjected to sufficient heat exchange with a cooling medium in the cooling pipeline, and the temperature is reduced to the design temperature so as to meet the temperature requirement of the water ring vacuum pump 4 on the working liquid.
The separator tank condenser 9 is a gas condensing device having a cooling line and a material line. The expanding pipe 10 is a small-sized gas-liquid separation tank. Wherein the cooling line connects upstream and downstream cooling medium lines, such as cooling water lines. The feed port 91 (material pipeline) of the separator condenser 9 is connected to the gas phase discharge port 52 of the gas-liquid separator 5, and the discharge port 92 is connected to the feed port 101 of the expanding pipe 10. The gas phase discharge port 102 of the expanding pipe 10 is connected with a downstream VOC adsorption device, and the liquid phase discharge port 103 is connected with a downstream condensate recovery pipeline for further separating condensed dichloromethane and nitrogen.
The mixed gas separated in the gas-liquid separation tank 5 is condensed to a design temperature (for example, a condensation temperature of methylene dichloride) by a separation tank condenser 9, and is separated into a separation condensate and a separation noncondensable gas in an expanding pipe 10. Because the condensing temperature of nitrogen is about-200 â and the condensing temperature of methylene chloride is about 40 â, the separator tank condenser 9 is designed to be able to condense gaseous methylene chloride into liquid methylene chloride, but not to condense nitrogen into liquid nitrogen. Thus, the separated condensate is liquid-phase dichloromethane, and is sent to a downstream condensate recovery device through a liquid-phase discharge port 103. The separated noncondensable gas comprises gas-phase dichloromethane and nitrogen components, and is sent to a downstream VOC adsorption device through a gas-phase discharge port 102. Because of the inert gas property of nitrogen, the adsorption effect of the VOC adsorption device on methylene dichloride is not influenced.
A third embodiment of the present invention provides a refining method, comprising at least the following steps.
And S1, heating the crude white oil to a designed temperature (130-150 â for example) by using a kettle-type reboiler 1, reducing the internal pressure of the kettle-type reboiler 1 to the designed pressure (30-50 kPa for example) by using a water ring vacuum pump 4, and distributing nitrogen into the crude white oil by using a gas distributor 14 of the kettle-type reboiler 1 so as to carry out reduced pressure rectification and nitrogen gas on the crude white oil, so that the crude white oil is separated into essential white oil and tail gas.
The feed inlet 11 (liquid distributor) of the kettle-type reboiler 1 is connected with an upstream crude white oil pipeline, the gas phase discharge outlet 12 is connected with the feed inlet 21 of the tower top condenser 2, the liquid phase discharge outlet 13 is connected with a downstream essential white oil pipeline, the gas distributor 14 is connected with an upstream nitrogen pipeline, and the tower top reflux outlet 15 is connected with the liquid phase discharge outlet 23 of the tower top condenser 2;
the controller 44 of the water ring vacuum pump 4 controls the rotation speed of the water ring vacuum pump 4 according to the detection data of the top pressure sensor 16 inside the kettle-type reboiler 1.
Preferably, the heating temperature of the crude white oil in the kettle reboiler 1 is not lower than 140 â. Optionally, the nitrogen temperature fed to the kettle reboiler 1 is not lower than 140 â to maintain the temperature of the crude white oil.
And S2, condensing the tail gas to a designed temperature (such as the condensing and liquefying temperature of dichloromethane) by utilizing the tower top condenser 2 so as to separate the tail gas into condensate and noncondensable gas.
The feed inlet 21 of the tower top condenser 2 is connected with the gas phase discharge outlet 12 of the kettle type reboiler 1, the gas phase discharge outlet 22 is connected with the feed inlet 31 of the vacuum buffer tank 3, and the liquid phase discharge outlet 23 is connected with the tower top reflux outlet 15 of the kettle type reboiler 1;
And S3, reducing pressure fluctuation of the kettle type reboiler 1 and the tower top condenser 2 by utilizing the vacuum buffer tank 3.
The feed port 31 of the vacuum buffer tank 3 is connected with the gas phase discharge port 22 of the tower top condenser 2, and the discharge port 32 is connected with the air suction port 41 of the water ring vacuum pump 4;
And S4, utilizing a water ring vacuum pump 4 to provide power for gas-phase materials in the kettle type reboiler 1, the tower top condenser 2 and the vacuum buffer tank 3 so as to enable the gas-phase materials to move in a pipeline and equipment, and utilizing working fluid in the water ring vacuum pump 4 to mix white oil components in the noncondensable gas and separate the white oil components in the noncondensable gas from the gas-phase components of dichloromethane and nitrogen so as to form mixed gas-liquid.
The air suction port 41 of the water ring vacuum pump 4 is connected with the discharge port 32 of the vacuum buffer tank 3, the output port 42 is connected with the feed port 51 of the gas-liquid separation tank 5, and the water supplementing port 43 is connected with the liquid phase discharge port 73 of the aeration tank 7 and the upstream water supplementing pipeline;
And S5, separating the mixed gas and the liquid into mixed gas and mixed liquid by utilizing a gas-liquid separation tank 5, and recycling and treating the mixed gas by utilizing downstream equipment.
The feed inlet 51 of the gas-liquid separation tank 5 is connected with the output port 42 of the water ring vacuum pump 4, the gas phase discharge port 52 is connected with the downstream VOC adsorption device, and the liquid phase discharge port 53 is connected with the feed inlet 61 of the oil separation tank 6.
The step may further include the following:
The mixed gas is cooled to a design temperature (for example, a condensing and liquefying temperature of methylene dichloride) by a separator condenser 9, separated into a separated noncondensable gas and a separated condensate by a diameter-enlarging pipe 10, and the separated noncondensable gas and the separated condensate are recovered by downstream equipment, respectively.
The feed port 91 of the separator condenser 9 is connected with the gas phase discharge port 52 of the gas-liquid separator 5, and the discharge port 92 is connected with the feed port 101 of the expanding pipe 10. The liquid phase discharge port 103 of the expanding pipe 10 is connected with a downstream condensate recovery pipeline, and the gas phase discharge port 102 is connected with a downstream VOC adsorption device.
And S6, separating the white oil component in the mixed solution by utilizing an oil separation groove 6 to obtain oil separation liquid.
The feed inlet 61 of the oil separation tank 6 is connected with the liquid phase discharge outlet 53 of the gas-liquid separation tank 5, and the discharge outlet 62 is connected with the feed inlet 71 of the aeration tank 7;
And S7, heating and aerating oil-separating liquid by using an aeration tank 7, separating out gaseous methylene dichloride to form aeration gas and aeration liquid, recycling and treating the aeration gas by using downstream equipment, and supplying the aeration liquid serving as working liquid to the water ring vacuum pump 4.
The feed inlet 71 of aeration tank 7 connects the discharge gate 62 of oil separator 6, and the gas phase discharge gate 72 connects the downstream VOC adsorption equipment, and the liquid phase discharge gate 73 connects the moisturizing mouth 43 of water ring vacuum pump 4.
Preferably, the oil barrier is heated to a design temperature, such as above the vaporization temperature (40 â) of methylene chloride, using aeration tank 7. Preferably, the oil barrier is heated to above 50 â by means of the aeration tank 7.
The step may further include the following:
the water ring pump condenser 8 is used for cooling the aeration liquid to the design temperature, and then the aeration liquid is provided for the water ring vacuum pump 4 to be used as working liquid.
The feed inlet 81 of the water ring pump condenser 8 is connected with the liquid phase discharge port 72 of the aeration tank 7, and the discharge port 82 is connected with the water supplementing port 43 of the water ring vacuum pump 4.
In summary, the embodiment of the invention provides a white oil refining system and a refining method for recycling lithium battery diaphragm extract. The heating temperature of crude white oil in a white oil refining system is 140 â, the purity of nitrogen gas extracted by nitrogen is more than 99.9%, the outlet temperature of a condenser which is not condensed in the white oil refining system is 40 â, the vacuum degree of a vacuum system is 50kPa, noncondensable gas entering a vacuum pump contains trace methylene dichloride and white oil, and the methylene dichloride content in refined white oil is less than or equal to 50ppm. The vacuum pump adopts a water ring vacuum pump to remove white oil components in non-condensable gas (white oil fume in non-condensing gas enters wastewater), and the non-condensable gas continuously enters the VOC recovery adsorption device to further recover dichloromethane. The water ring vacuum pump removes white oil components with high boiling point, so that the service life of the subsequent VOC device adsorption material can be prolonged. And (3) removing white oil from the wastewater discharged by the water ring vacuum pump through an oil removal tank, and then, feeding the wastewater into an aeration device. The aeration device is heated to 50 â, the auxiliary air aeration stripping can remove dichloromethane in the wastewater, and the waste gas which is exposed and contains dichloromethane also enters the VOC recovery adsorption device. The aerated water enters a water ring vacuum pump for recycling after being cooled.
It should be noted that the above embodiments are only examples. The technical schemes of the embodiments can be combined, and all the technical schemes are within the protection scope of the invention.
It should be noted that, the order of steps in the embodiments of the present invention may be changed according to actual needs, the order of steps may be changed, serial processing may be changed to parallel processing, and the present invention is not limited to the order of steps listed in the embodiments.
The terms "upper," "lower," "top," "bottom," and the like are used for convenience in describing and simplifying the description only, and do not denote or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.
Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
The white oil refining system and the refining method for recycling the diaphragm extract of the lithium battery provided by the invention are described in detail. Any obvious modifications to the present invention, without departing from the spirit thereof, would constitute an infringement of the patent rights of the invention and would take on corresponding legal liabilities.
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