Vacuum pump sealing liquid recycling system

Abstract

The utility model relates to the technical field of chemical production tail gas treatment, in particular to a vacuum pump sealing liquid recycling system. The vacuum pump sealing liquid recycling system comprises an evaporator, an ejector, a vacuum hot well and a vacuum liquid circulating pump, the output end of the vacuum hot well is communicated with the input end of the vacuum liquid circulating pump, and the output end of the vacuum liquid circulating pump is communicated with the input end of the evaporator and the input end of the ejector. The output end of the evaporator is communicated with the input end of the ejector, the input end of the ejector is further externally connected with industrial tail gas, and the output end of the ejector is communicated with the input end of the vacuum hot well. The vacuum pump sealing liquid recycling system is low in energy consumption, acetylene, propane, alpha-PY, NMP, NVP and other process materials in tail gas are recycled, raw material consumption and product loss are reduced, emission of three wastes is reduced, and operation cost is saved.

Description

Technical Field

[0001] This utility model relates to the field of chemical production tail gas treatment technology, and in particular to a vacuum pump sealing fluid recycling system. Background Technology

[0002] Currently, the main NVP production process uses the acetylene method. Acetylene reacts with α-pyrrolidone under medium pressure to produce NVP, and NVP is purified by distillation before polymerization. To prevent the decomposition and explosion of acetylene gas, propane is added. Since α-PY, NMP, and NVP are all high-boiling-point (over 200℃) organic compounds, they require high-vacuum distillation purification. Existing processes use numerous steam jet vacuum pumps. Dissolved acetylene, propane, α-PY, NMP, and NVP are discharged into the atmosphere with the vacuum pump exhaust, causing material loss, environmental pollution, and increased difficulty in waste gas and wastewater treatment. Steam jetting is energy-intensive, inefficient, and consequently, has high operating costs. The NVP and its supporting α-PY production unit contain approximately 15% propane and acetylene in the vacuum non-condensable gas discharged from the top of the light component tower. This gas is flammable and explosive and needs to be sent to incineration facilities for treatment. However, long-distance pipeline transportation poses significant risks. Therefore, this presents challenges to the site selection, construction, and scale investment of the production unit and supporting facilities, requiring comprehensive consideration of upstream and downstream factors. This often limits and increases the investment difficulty and production and operating costs of the project.

[0003] Utility model patent CN221244016U discloses a vacuum control device for an NMP dehydration tower, comprising: connecting a vacuum pump to the NMP dehydration tower to extract the generated gas, separating the extracted gas using a gas-liquid separator to obtain NMP liquid and discharging the gas; using a cooler located between the gas-liquid separator and the vacuum pump to cool the separated NMP liquid, and inputting the cooled NMP liquid as working fluid into the vacuum pump to replace part of the NMP working fluid to achieve the purpose of cooling; returning the replaced NMP working fluid to the dehydration tower reflux tank through the drain lines of the vacuum pump and the gas-liquid separator for recycling and distillation to obtain NMP product; and providing an NMP replenishment line at the inlet of the gas-liquid separator to replenish the gas-liquid separator with NMP working fluid collected from the outlet of the cooler.

[0004] The vacuum control device of the NMP dehydration tower mentioned above can effectively improve the vacuum level of the NMP dehydration tower and reduce energy consumption and wastewater generation. However, it cannot absorb raw materials such as acetylene and propane in the production process as much as possible, and a lot of waste gas and waste liquid will still be generated. Some industrial raw materials cannot be fully utilized, and the recovery efficiency is low. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a vacuum pump sealing fluid recycling system. This vacuum pump sealing fluid recycling system has low energy consumption and recovers process materials such as acetylene, propane, α-PY, NMP and NVP from the exhaust gas for recycling, thereby reducing raw material consumption and product loss, reducing the emission of waste gas, wastewater, and solid waste, and saving operating costs.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A vacuum pump sealing fluid recycling system includes an evaporator, an ejector, a vacuum hot well, and a vacuum fluid circulation pump. The output end of the vacuum hot well is connected to the input end of the vacuum fluid circulation pump. The output end of the vacuum fluid circulation pump is connected to the input ends of the evaporator and the ejector, respectively. The output end of the evaporator is connected to the input end of the ejector. The input end of the ejector is also connected to industrial exhaust gas. The output end of the ejector is connected to the input end of the vacuum hot well.

[0008] Furthermore, the vacuum liquid circulation pump is connected to the vacuum hot well via a liquid delivery pipe, the vacuum liquid circulation pump is connected to the ejector via a first connecting pipe, the vacuum liquid circulation pump is connected to the evaporator via a second connecting pipe, and the vacuum liquid circulation pump is also connected to a first residual liquid recovery pipe, which is used to recover excess circulating working fluid in the vacuum hot well.

[0009] Furthermore, the vacuum hot well is internally equipped with a guide pipe and a liquid level plate. The guide pipe is spaced apart from the output end of the ejector, and the liquid level plate is located on one side of the guide pipe. The guide pipe and the liquid level plate divide the vacuum hot well into a gas-liquid mixing zone and a circulating working fluid extraction zone.

[0010] Furthermore, the infusion tube obtains circulating working fluid through the circulating working fluid extraction zone and feeds it into the vacuum fluid circulation pump.

[0011] Furthermore, the top of the vacuum hot well is provided with a liquid inlet pipe, which is used to input NMP / α-PY to replenish the circulating working fluid, and the liquid inlet pipe is located in the gas-liquid mixing zone.

[0012] Furthermore, a waste gas recovery pipe is also provided at the top of the vacuum hot well, which is used to recover non-condensable gases.

[0013] Furthermore, the circulating working fluid extraction zone of the vacuum hot well is equipped with a first liquid level sensor controller, and the first residual liquid recovery pipe is equipped with a first electrically controlled valve. The first liquid level sensor controller and the first electrically controlled valve are electrically connected.

[0014] Furthermore, the evaporator is a U-tube heater, with heat transfer oil connected to the outside of the tube side and circulating working fluid inside the shell side of the evaporator.

[0015] Furthermore, the evaporator is equipped with a second liquid level sensor controller, and the second connecting pipe is equipped with a second electrically controlled valve, and the second liquid level sensor controller and the second electrically controlled valve are electrically connected.

[0016] Furthermore, the evaporator is also provided with a second residual liquid recovery pipe, and the second residual liquid recovery pipe is provided with a third electrically controlled valve. The third electrically controlled valve is electrically connected to the second liquid level sensor controller, and the second residual liquid recovery pipe is used to recover excess circulating working liquid in the evaporator.

[0017] The beneficial effects of this utility model are as follows: This utility model discloses a vacuum pump sealing fluid recycling system, including an evaporator, an ejector, a vacuum hot well, and a vacuum fluid circulation pump. The output end of the vacuum hot well is connected to the input end of the vacuum fluid circulation pump. The output end of the vacuum fluid circulation pump is connected to the input ends of the evaporator and the ejector, respectively. The output end of the evaporator is connected to the input end of the ejector. The input end of the ejector is also connected to industrial exhaust gas. The output end of the ejector is connected to the input end of the vacuum hot well. The number of ejectors is determined according to requirements. Steam generated by the evaporator serves as the first supply source for the ejectors, providing motive steam. Low-temperature circulating working fluid directly input by the vacuum liquid circulation pump serves as the second supply source for the ejectors, providing motive liquid flow. Mixing and condensation occur at the ejector inlet to obtain the required low-pressure vacuum, while simultaneously adsorbing the input exhaust gas. The vacuum hot well is a buffer facility that connects and seals all ejector outlets and the vacuum liquid circulation pump inlet into a single unit. The vacuum liquid circulation pump draws circulating working fluid from the vacuum hot well to adsorb exhaust gas for circulation. The evaporator heats the circulating working fluid, generating steam at a certain pressure to provide continuous and stable motive steam for the ejectors. The vacuum liquid circulation pump pumps the circulating working fluid for circulation. This vacuum pump sealing fluid recycling system has low energy consumption and recovers process materials such as acetylene, propane, α-PY, NMP, and NVP from the exhaust gas for recycling, reducing raw material consumption and product loss, reducing waste emissions, and saving operating costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] Explanation of reference numerals in the attached drawings: 1-Evaporator, 2-Ejector, 3-Vacuum hot well, 4-Vacuum liquid circulation pump, 5-Liquid delivery pipe, 6-First connecting pipe, 7-Second connecting pipe, 8-First residual liquid recovery pipe, 9-Guide pipe, 10-Liquid level plate, 11-Liquid inlet pipe, 12-Waste gas recovery pipe, 13-First liquid level sensor controller, 14-First electric control valve, 15-Second liquid level sensor controller, 16-Second electric control valve, 17-Second residual liquid recovery pipe, 18-Third electric control valve. Detailed Implementation

[0020] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0021] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0022] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0023] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. The meaning of such spatial relative terms includes different orientations of the device in use or operation, in addition to the orientation depicted in the figure. For example, if the device in the figure is flipped, then an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0024] Example 1:

[0025] like Figure 1 As shown, this embodiment provides a vacuum pump sealing fluid recycling system, which includes an evaporator 1, an ejector 2, a vacuum hot well 3, and a vacuum fluid circulation pump 4. The output end of the vacuum hot well 3 is connected to the input end of the vacuum fluid circulation pump 4. The output end of the vacuum fluid circulation pump 4 is connected to the input ends of the evaporator 1 and the ejector 2, respectively. The output end of the evaporator 1 is connected to the input end of the ejector 2. The input end of the ejector 2 is also connected to industrial exhaust gas. The output end of the ejector 2 is connected to the input end of the vacuum hot well 3. In actual use, the number of ejectors 2 is set according to requirements. The steam generated by the evaporator 1 is the first supply source for ejectors 2, providing power steam. The low-temperature circulating working fluid directly input by the vacuum liquid circulation pump 4 is the second supply source for ejectors 2, providing power liquid flow. Mixing and condensation are carried out at the inlet of ejectors 2 to obtain the required vacuum low pressure, while adsorbing the input exhaust gas. The vacuum hot well 3 is a buffer facility that connects and seals all the outlets of ejectors 2 and the inlet of the vacuum liquid circulation pump 4 into a whole. At the same time, the vacuum liquid circulation pump 4 draws circulating working fluid from the vacuum hot well 3 to adsorb exhaust gas and circulate it. The evaporator 1 is used to heat the circulating working fluid to generate steam at a certain pressure to provide continuous and stable power steam for ejectors 2. The vacuum liquid circulation pump 4 is used to pump the circulating working fluid for circulation.

[0026] In this embodiment, the vacuum liquid circulation pump 4 is connected to the vacuum hot well 3 via the delivery pipe 5, the vacuum liquid circulation pump 4 is connected to the ejector 2 via the first connecting pipe 6, and the vacuum liquid circulation pump 4 is connected to the evaporator 1 via the second connecting pipe 7. The vacuum liquid circulation pump 4 is also connected to a first residual liquid recovery pipe 8, which is used to recover excess circulating working fluid in the vacuum hot well 3. In actual use, the vacuum liquid circulation pump 4 obtains circulating working fluid from the vacuum hot well 3 through the delivery pipe 5 and distributes the circulating working fluid. A portion is transported to the ejector 2 through the first connecting pipe 6, and another portion is transported to the evaporator 1 through the second connecting pipe 7. The first residual liquid recovery pipe 8 connected to the vacuum liquid circulation pump 4 is used to recover excess circulating working fluid in the vacuum hot well 3.

[0027] In this embodiment, the vacuum hot well 3 is internally equipped with a guide pipe 9 and a liquid level plate 10. The guide pipe 9 is spaced apart from the output end of the injector 2, and the liquid level plate 10 is located on one side of the guide pipe 9. The guide pipe 9 and the liquid level plate 10 divide the vacuum hot well 3 into a gas-liquid mixing zone and a circulating working fluid extraction zone. In actual use, the guide pipe 9 is used to reduce the temperature of the material at the outlet of the injector 2 while increasing the solubility of acetylene, propane, etc. The liquid level plate 10 is used to ensure that the liquid level in the gas-liquid mixing zone is maintained at a certain height for a long time, increasing the solubility of acetylene, propane, etc. in the circulating working fluid. The circulating working fluid extraction zone located on one side of the liquid level plate 10 facilitates the extraction of circulating working fluid by the vacuum liquid circulation pump 4.

[0028] In this embodiment, the infusion pipe 5 obtains circulating working fluid through the circulating working fluid extraction zone and delivers it to the vacuum fluid circulation pump 4. In actual use, the vacuum fluid circulation pump 4 obtains circulating working fluid through the infusion pipe 5, and the circulating working fluid is stored in the circulating working fluid extraction zone of the vacuum hot well 3.

[0029] In this embodiment, a liquid inlet pipe 11 is provided at the top of the vacuum hot well 3. The liquid inlet pipe 11 is used to input NMP / α-PY to replenish the circulating working fluid. The liquid inlet pipe 11 is located in the gas-liquid mixing zone. In actual use, the circulating working fluid is a solution mainly composed of NMP / α-PY. As the circulation proceeds, it absorbs acetylene and propane in the exhaust gas. When the circulating working fluid in the entire cycle is insufficient, NMP / α-PY is input through the liquid inlet pipe 11 to replenish the circulating working fluid.

[0030] In this embodiment, a waste gas recovery pipe 12 is also provided at the top of the vacuum hot well 3. The waste gas recovery pipe 12 is used to recover non-condensable gases. In actual use, non-condensable gases will exist in the vacuum hot well 3. The main components of the non-condensable gases are water vapor containing acetylene and propane. The non-condensable gases are recovered through the recovery pipe, and then the acetylene and propane are recovered by external degassing tanks and other recovery equipment for recycling.

[0031] In this embodiment, the circulating working fluid extraction zone of the vacuum hot well 3 is equipped with a first liquid level sensor controller 13, and the first residual liquid recovery pipe 8 is equipped with a first electrically controlled valve 14. The first liquid level sensor controller 13 and the first electrically controlled valve 14 are electrically connected. In actual use, the first liquid level sensor controller 13 is used to monitor the liquid level in the vacuum hot well 3 and control the connected devices. When the circulating working fluid level in the vacuum hot well 3 reaches the set maximum threshold height, the first liquid level sensor controller 13 controls the first electrically controlled valve 14 to open, and the circulating working fluid in the circulating working fluid extraction zone of the vacuum hot well 3 is discharged and recovered through the first residual liquid recovery pipe 8. When the circulating working fluid level in the vacuum hot well 3 is lower than the set maximum threshold height, the first electrically controlled valve 14 is closed. Similarly, the first liquid level sensor controller 13 is also set with a corresponding minimum threshold height. When the circulating working fluid level in the vacuum hot well 3 is lower than the set minimum threshold height, NMP / α-PY is input into the inlet pipe 11 to replenish the circulating working fluid.

[0032] Example 2:

[0033] like Figure 1 As shown, based on Embodiment 1, the evaporator 1 is a U-tube heater. The tube side of the evaporator 1 is connected to external heat transfer oil, and the shell side contains a circulating working fluid. In actual use, conventional NMP / α-PY production requires a coil-type reactor. The coil-type reactor needs heat transfer oil to provide heating to support the reaction. High-temperature heat transfer oil (250-300℃) is directly obtained from the original production unit to heat (190-200℃) the circulating working fluid in the shell side, causing it to evaporate and generate steam at a certain pressure (50-100KPaA) to provide continuous and stable power steam for the ejector 2.

[0034] In this embodiment, the evaporator 1 is equipped with a second liquid level sensor controller 15, and the second connecting pipe 7 is equipped with a second electrically controlled valve 16. The second liquid level sensor controller 15 and the second electrically controlled valve 16 are electrically connected. In actual use, the second liquid level sensor controller 15 is used to monitor the liquid level in the evaporator 1 and control the connected devices. When the liquid level of the circulating working fluid in the evaporator 1 is lower than the set minimum threshold height, the second liquid level sensor controller 15 controls the second electrically controlled valve 16 to open, and the second connecting pipe 7 is opened. The circulating working fluid in the evaporator 1 is replenished by the continuous operation of the vacuum liquid circulation pump 4. When the liquid level of the circulating working fluid in the evaporator 1 is higher than the set minimum threshold height, the second liquid level sensor controller 15 controls the second electrically controlled valve 16 to close.

[0035] In this embodiment, the evaporator 1 is further provided with a second residual liquid recovery pipe 17, and the second residual liquid recovery pipe 17 is provided with a third electrically controlled valve 18. The third electrically controlled valve 18 is electrically connected to a second liquid level sensor controller 15. The second residual liquid recovery pipe 17 is used to recover excess circulating working fluid in the evaporator 1. In actual use, the second residual liquid recovery pipe 17 is used to recover excess circulating working fluid in the evaporator 1. When the level of the circulating working fluid in the evaporator 1 reaches the set maximum threshold height, the second liquid level sensor controller 15 controls the third electrically controlled valve 18 to open, and the circulating working fluid in the evaporator 1 is discharged and recovered through the second residual liquid recovery pipe 17. When the level of the circulating working fluid in the evaporator 1 is lower than the set maximum threshold height, the second liquid level sensor controller 15 controls the third electrically controlled valve 18 to close.

[0036] All technical features in this embodiment can be freely combined according to actual needs. The above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model. Technologies, shapes, and structural parts not described in detail in this utility model are all known technologies.

[0037] The above embodiments are preferred implementations of this utility model. In addition, other implementations are also included. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this utility model.

Claims

1. A vacuum pump sealing fluid recycling system, characterized in that: It includes an evaporator (1), an ejector (2), a vacuum hot well (3), and a vacuum liquid circulation pump (4). The output end of the vacuum hot well (3) is connected to the input end of the vacuum liquid circulation pump (4). The output end of the vacuum liquid circulation pump (4) is connected to the input ends of the evaporator (1) and the ejector (2), respectively. The output end of the evaporator (1) is connected to the input end of the ejector (2). The input end of the ejector (2) is also connected to industrial exhaust gas. The output end of the ejector (2) is connected to the input end of the vacuum hot well (3).

2. The vacuum pump sealing fluid recycling system according to claim 1, characterized in that: The vacuum liquid circulation pump (4) is connected to the vacuum hot well (3) through the liquid delivery pipe (5), the vacuum liquid circulation pump (4) is connected to the ejector (2) through the first connecting pipe (6), the vacuum liquid circulation pump (4) is connected to the evaporator (1) through the second connecting pipe (7), and the vacuum liquid circulation pump (4) is also connected to the first residual liquid recovery pipe (8), which is used to recover the excess circulating working fluid in the vacuum hot well (3).

3. The vacuum pump sealing fluid recycling system according to claim 2, characterized in that: The vacuum hot well (3) is equipped with a guide pipe (9) and a liquid level plate (10). The guide pipe (9) is spaced apart from the output end of the ejector (2). The liquid level plate (10) is located on one side of the guide pipe (9). The guide pipe (9) and the liquid level plate (10) divide the vacuum hot well (3) into a gas-liquid mixing zone and a circulating working fluid extraction zone.

4. The vacuum pump sealing fluid recycling system according to claim 3, characterized in that: The infusion tube (5) obtains circulating working fluid through the circulating working fluid extraction zone and feeds it into the vacuum fluid circulation pump (4).

5. A vacuum pump sealing fluid recycling system according to claim 3, characterized in that: The top of the vacuum hot well (3) is provided with a liquid inlet pipe (11), which is used to input NMP / α-PY to replenish the circulating working fluid. The liquid inlet pipe (11) is located in the gas-liquid mixing zone.

6. A vacuum pump sealing fluid recycling system according to claim 3, characterized in that: The top of the vacuum hot well (3) is also provided with a waste gas recovery pipe (12), which is used to recover non-condensable gas.

7. A vacuum pump sealing fluid recycling system according to claim 3, characterized in that: The vacuum hot well (3) is equipped with a first liquid level sensor controller (13) in the circulating working fluid extraction area, and a first electric control valve (14) is provided in the first residual liquid recovery pipe (8). The first liquid level sensor controller (13) and the first electric control valve (14) are electrically connected.

8. A vacuum pump sealing fluid recycling system according to claim 1, characterized in that: The evaporator (1) is a U-tube heater. The tube side of the evaporator (1) is connected to heat transfer oil, and the shell side of the evaporator (1) is filled with circulating working fluid.

9. A vacuum pump sealing fluid recycling system according to claim 2, characterized in that: The evaporator (1) is equipped with a second liquid level sensor controller (15), and the second connecting pipe (7) is equipped with a second electric control valve (16). The second liquid level sensor controller (15) and the second electric control valve (16) are electrically connected.

10. A vacuum pump sealing fluid recycling system according to claim 9, characterized in that: The evaporator (1) is also provided with a second residual liquid recovery pipe (17), and the second residual liquid recovery pipe (17) is provided with a third electrically controlled valve (18). The third electrically controlled valve (18) is electrically connected to the second liquid level sensor controller (15). The second residual liquid recovery pipe (17) is used to recover excess circulating working liquid in the evaporator (1).

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