A dual-phase stainless steel vacuum unit system with low-temperature condensation trapping

Abstract

The utility model relates to a kind of dual-phase stainless steel vacuum unit system with low-temperature condensation trapping, including double parallel pre low-temperature condenser, vacuum unit and refrigerator unit, double parallel pre low-temperature condenser includes first pre-condenser and second pre-condenser, vacuum unit and refrigerator unit are connected with double parallel pre low-temperature condenser respectively, refrigerator unit provides cold source for double parallel pre low-temperature condenser, and the refrigeration system of vacuum unit is formed;Vacuum unit includes roots vacuum pump and screw vacuum pump;Double parallel pre low-temperature condenser is connected with refrigerant insulation box by refrigerant circulating pump, and refrigerant insulation box is connected with refrigerator unit.The utility model is provided with double parallel shell-and-tube low-temperature condenser arranged vertically in front of the inlet of vacuum pump group, which can pre-condense and separate condensable and strongly corrosive steam deeply;Through the structure combination of roots vacuum pump and screw vacuum pump in series, efficient air extraction in wide pressure range is realized.

Description

Technical Field

[0001] This utility model relates to the field of vacuum processing equipment technology, and in particular to a duplex stainless steel vacuum unit system with low-temperature condensation capture, which is suitable for chemical, pharmaceutical, electronic, nuclear industry and other fields, and is a corrosion-resistant and pollution-resistant vacuum unit system for processing media containing strong acid corrosive liquids, large amounts of corrosive solvent liquids and other media. Background Technology

[0002] In industries such as fine chemicals, pharmaceutical synthesis, specialty new material polymerization, nuclear fuel processing, and lithium battery manufacturing, production processes often generate large amounts of highly corrosive, toxic, or easily condensable chemical media, such as solvent vapors, acidic gases, and particulate matter. These processes typically require a vacuum environment, such as vacuum distillation, concentration, and drying, thus necessitating vacuum units to establish and maintain the required low-pressure environment.

[0003] Currently, traditional vacuum units commonly used in the industry, such as screw vacuum pump units and rotary vane vacuum pump units, exhibit the following problems when dealing with the aforementioned special media: (1) Corrosion and pollution problems: Traditional vacuum pumps are mostly made of cast iron, carbon steel or ordinary austenitic stainless steel. Under the action of strong corrosive media (especially media containing chloride ions), the pump body and key components such as the internal rotor are easily corroded. This not only shortens the service life of the equipment, but the corrosion products will also pollute the process flow and the final product, affecting product quality.

[0004] (2) Difficulty in handling condensable steam: When a large amount of condensable steam (such as solvents and water vapor) enters the vacuum pump directly, it will emulsify and chemically react with the working fluid (such as oil) inside the pump, resulting in deterioration of the working fluid performance and a decrease in vacuum. At the same time, the steam condenses in the pump cavity, which may cause liquid hammer, scaling, and damage to core components such as the rotor and pump body.

[0005] (3) Complex system and high energy consumption: In order to protect the vacuum pump and handle condensable steam, it is usually necessary to add a large external condenser before the pump, or to install complex gas ballast, cold trap, oil-gas separator and other devices after the pump. This not only leads to low system integration and large footprint, but also increases the initial investment and subsequent energy consumption, and the reliability and maintainability of the equipment are also challenged.

[0006] (4) Limitations in pumping performance: It is difficult for a single type of vacuum pump to maintain high pumping efficiency across a wide pressure range from rough vacuum to high vacuum. For example, Roots vacuum pumps have a high pumping speed at high vacuum but a limited compression ratio, requiring a backing pump; while when a screw vacuum pump is used as a backing pump, the ultimate vacuum of the system is limited by its own ultimate vacuum capability.

[0007] Therefore, there is an urgent need in this field for a vacuum unit system that is highly integrated, highly corrosion resistant, can effectively pre-treat condensable and corrosive steam, and can operate stably and efficiently over a wide pressure range. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a duplex stainless steel vacuum unit system with low-temperature condensation capture that is compact in structure, corrosion-resistant, pollution-resistant, can effectively capture and process condensable and corrosive steam, and has stable pumping performance.

[0009] The purpose of this utility model is achieved as follows: A duplex stainless steel vacuum unit system with low-temperature condensation trapping includes a dual parallel pre-low-temperature condenser, a vacuum unit, and a refrigeration unit. The dual parallel pre-low-temperature condenser includes a first pre-condenser and a second pre-condenser. The vacuum unit and the refrigeration unit are respectively connected to the dual parallel pre-low-temperature condenser. The refrigeration unit provides a cold source for the dual parallel pre-low-temperature condenser, forming a refrigeration system for the vacuum unit. The inlet of the first pre-condenser is connected to the first inlet main valve, and the first pre-condenser is also connected to the first steam purge port. The inlet of the second pre-condenser is connected to the second inlet main valve. The outlets of the first and second pre-condensers are respectively connected to a liquid collection tank, and the liquid collection tank is connected to a liquid level transmitter. The vacuum unit is connected to the outlet of the dual parallel pre-low temperature condenser through the vacuum unit inlet valve. The vacuum unit includes a Roots vacuum pump and a screw vacuum pump. The Roots vacuum pump is connected to the dual parallel pre-cryogenic condenser via a primary pressure transmitter and a primary temperature transmitter. The Roots vacuum pump is connected to the screw vacuum pump via a secondary pressure transmitter, a check valve, and a secondary temperature transmitter. The screw vacuum pump's outlet pipe is equipped with a tertiary pressure transmitter and a tertiary temperature transmitter. The Roots vacuum pump is connected to a cooling water switch valve via a Roots pump cooling water valve, and the screw vacuum pump is connected to a cooling water switch valve via a screw pump cooling water valve. The cooling water switch valve is connected to the inlet. The screw vacuum pump's outlet pipe is connected to a silencer. The first and second pre-condensers are respectively connected to a refrigerant insulation tank via a refrigerant circulation pump. The refrigerant insulation tank is connected to a refrigeration unit, which includes a third condenser, an evaporator, a screw compressor, and an oil-gas separator. The refrigerant circulation pump is connected to the third condenser, the third condenser is connected to the evaporator, the chilled water inlet of the evaporator is connected to the screw compressor, the screw compressor is connected to the oil-gas separator, and the chilled water outlet of the evaporator is connected to the discharge ports of the first and second pre-condensers. A four-stage temperature transmitter is installed on the pipeline connecting the refrigerant circulation pump and the third condenser, and a five-stage temperature transmitter is installed on the pipeline connecting the first and second pre-condensers and the evaporator.

[0010] Furthermore, the second pre-condenser also includes a second steam purge port; the first inlet main valve and the second inlet main valve are connected in sequence through pipelines, and the first inlet main valve and the second inlet main valve are respectively connected to the main air inlet, which is connected to the on-site chemical reaction device.

[0011] Furthermore, the liquid collection tank is connected to a third steam purging port, and a liquid collection tank drain port is provided at the bottom of the liquid collection tank.

[0012] Furthermore, the inlet and outlet of the dual parallel pre-cooled condenser are also connected to a bypass pipeline, which is respectively connected to the gas inlet and outlet of the first pre-condenser and the second pre-condenser; a bypass valve is provided on the bypass pipeline.

[0013] Furthermore, a cooling water flow meter is installed on the pipeline connecting the cooling water switch valve to the cooling water valve of the Roots pump and the cooling water valve of the screw pump.

[0014] Furthermore, the muffler is provided with a muffler exhaust port and a drain port, and a muffler drain valve is provided at the drain port.

[0015] Furthermore, the refrigerant circulation pump is connected to the refrigerant insulation tank via an expansion joint and a filter in sequence.

[0016] Furthermore, the upper part of the refrigerant insulation box is provided with a refrigerant return port, a refrigerant replenishment port, and an overflow port; the lower part of the refrigerant insulation box is provided with a refrigerant outlet and a vent port; the top surface of the refrigerant insulation box is provided with a vent and an inspection and maintenance port; the refrigerant return port of the refrigerant insulation box is connected to a dual parallel pre-cooled condenser; and the refrigerant outlet of the refrigerant insulation box is connected to a filter via a pneumatic ball valve.

[0017] Furthermore, the muffler exhaust port of the muffler is connected to the exhaust gas treatment device. The exhaust gas treatment device can be configured together with the vacuum unit, or the exhaust gas of the vacuum unit can be directly connected to the exhaust gas treatment device of the large chemical plant system.

[0018] Furthermore, it also includes an intelligent control system that monitors the entire system. This control system includes an electrical control cabinet, which is electrically connected to the first inlet main valve, the second inlet main valve, the refrigeration unit, the dual parallel pre-cooled cryogenic condenser, the Roots vacuum pump, the screw vacuum pump, and various transmitters and valves. It is used to monitor the operating parameters of the entire unit and realize automatic control.

[0019] Compared with the prior art, the beneficial effects of this utility model are: This invention provides a duplex stainless steel vacuum unit system with cryogenic condensation trapping, comprising an inlet main valve, two parallel pre-cooled cryogenic condensers, a Roots vacuum pump, a screw vacuum pump, and a screw compressor cryogenic refrigeration system connected sequentially via pipelines, and equipped with an intelligent control system. The core components of this unit are made of corrosion-resistant duplex stainless steel. Two parallel vertically arranged cryogenic condensers are installed at the pump inlet front end, which can pre-condense and separate condensable and highly corrosive vapors. Through the series connection of the Roots vacuum pump and the screw vacuum pump and the intelligent control strategy, efficient and stable vacuuming over a wide pressure range is achieved. It possesses the following specific advantages: (1) Excellent structural stability and corrosion resistance: By using duplex stainless steel to manufacture the flow parts of core components such as condensers, Roots pumps and screw pumps, the entire system has excellent resistance to chloride pitting corrosion, crevice corrosion and stress corrosion cracking. It is particularly suitable for harsh chemical media environments, which greatly extends the service life of the equipment and reduces the failure rate and product contamination risk caused by corrosion.

[0020] (2) High-efficiency pretreatment and system protection structure: The innovative dual parallel pre-cooled condensers are arranged vertically, with process gas flowing through the shell side and low-temperature refrigerant flowing through the tube side, achieving efficient counter-current heat exchange. This structure can deeply condense most of the condensable and corrosive vapors into liquid and separate them before the process gas enters the vacuum pump unit, thus avoiding the risk of contamination, corrosion and liquid slugging of these media to the subsequent vacuum pump from the structural source, ensuring the long-term stable operation of the pump unit.

[0021] (3) Optimized pumping system structure: The mechanical pump combination structure of “Roots vacuum pump plus screw vacuum pump” in series is adopted. The Roots vacuum pump is responsible for providing a high pumping speed under high vacuum, and the screw vacuum pump is used as a backing pump to provide stable back pressure. This combination structure enables the system to maintain efficient and stable pumping capacity in a wide pressure range from rough vacuum to high vacuum (such as 5×10⁻² Pa).

[0022] (4) Intelligent structural control and safety: The system integrates pressure, temperature, level transmitters and automatic valves, and is managed by an intelligent control system to achieve automatic control based on the actual operating conditions of the system (such as the opening and closing of bypass valves and the automatic discharge of condensate). This structured control scheme not only improves the convenience and automation of operation, but also significantly improves the operational reliability and safety of the entire unit system through preset safety logic (such as overpressure and overtemperature protection).

[0023] (5) Compact integration and environmentally friendly structure: The low-temperature condensation and capture unit and the vacuum pump group are highly integrated into one system, and the need for external auxiliary equipment is reduced through structural optimization such as bypass pipelines, making the system structure more compact and occupying less space; at the same time, the pre-condensation and capture structure design helps to recover valuable solvents, reduce the tail gas treatment load, and meet environmental protection requirements. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall system flow of this utility model.

[0025] Figure 2 This is a schematic diagram of the process flow of the vacuum unit of this utility model.

[0026] Figure 3 This is a schematic diagram of the refrigeration system of this utility model.

[0027] in: 1. First pre-condenser; 1.1. First inlet main valve; 1.2. First steam purge port; 2. Second pre-condenser; 2. Second inlet main valve; 2.1. Second steam purge port; 2.2. Main air inlet; 3. Liquid collection tank; 4. Liquid level transmitter; 4.1. Third steam purge port; 4.2. Liquid collection tank drain port; 4.3. Vacuum unit; 5. Vacuum unit inlet valve; 5.1. Refrigerant insulation tank; 6. Refrigerant return port; 6.1. Refrigerant outlet; 6.2. Refill port; 6.3. Vent port; 6.4. Vent port; 6.5. Overflow port; 6.6. Inspection and maintenance port; 6.7. Insulation tank drain port; 6.6. Refrigeration unit; 7. Bypass pipeline; 8. Roots vacuum pump; 9. Screw vacuum pump. 10. Air pump, 11. Primary pressure transmitter, 12. Primary temperature transmitter, 13. Secondary pressure transmitter, 14. Secondary temperature transmitter, 15. Roots pump cooling water valve, 16. Check valve, 17. Tertiary pressure transmitter, 18. Tertiary temperature transmitter, 19. Screw pump cooling water valve, 20. Cooling water flow meter, 21. Silencer, 21.1. Silencer exhaust port, 21.2. Silencer drain valve, 22. Cooling water switch valve, 23. Third condenser, 24. Evaporator, 25. Screw compressor, 26. Oil-gas separator, 27. Quaternary temperature transmitter, 28. Fifth-stage temperature transmitter, 29. Refrigerant circulation pump, 30. Expansion joint, 31. Filter, 32. Electrical control cabinet. Detailed Implementation

[0028] To better understand the technical solution of this utility model, a detailed description will be provided below in conjunction with relevant illustrations. It should be understood that the specific embodiments described below are not intended to limit the specific implementation of the technical solution of this utility model, but are merely possible implementations of the technical solution of this utility model. It should be noted that the descriptions of the positional relationships of the components herein, such as component A being located above component B, are based on the relative positions of the components in the illustrations and are not intended to limit the actual positional relationships of the components. Example

[0029] See Figures 1-3 , Figure 1 A schematic diagram of the overall system flow of a duplex stainless steel vacuum unit system with cryogenic condensation trapping according to this utility model is shown. As shown in the figure, a duplex stainless steel vacuum unit system with cryogenic condensation trapping includes two parallel pre-cryogenic condensers, a vacuum unit 5, and a refrigeration unit 7. The two parallel pre-cryogenic condensers include a first pre-condenser 1 and a second pre-condenser 2. The vacuum unit 5 and the refrigeration unit 7 are respectively connected to the two parallel pre-cryogenic condensers. The refrigeration unit 7 provides a cold source for the two parallel pre-cryogenic condensers, forming the refrigeration system of the vacuum unit 5.

[0030] The inlet of the first pre-condenser 1 is connected to the first inlet main valve 1.1, and the first pre-condenser 1 is also connected to the first steam purge port 1.2. The inlet of the second pre-condenser 2 is connected to the second inlet main valve 2.1, and the second pre-condenser 2 also includes the second steam purge port 2.2. The first inlet main valve 1.1 and the second inlet main valve 2.1 are connected in sequence through pipelines, and the first inlet main valve 1.1 and the second inlet main valve 2.1 are respectively connected to the main air inlet 3, which is connected to the on-site chemical reaction device, i.e., the vacuum reaction tower.

[0031] The outlets of the first pre-condenser 1 and the second pre-condenser 2 are respectively connected to the liquid collection tank 4. The liquid collection tank 4 is connected to the liquid level transmitter 4.1. The liquid collection tank 4 is connected to the third steam purge port 4.2. The bottom of the liquid collection tank 4 is provided with a liquid collection tank drain port 4.3.

[0032] The vacuum unit 5 is connected to the outlet of the dual parallel pre-low temperature condenser through the vacuum unit inlet valve 5.1. The vacuum unit 5 includes a Roots vacuum pump 9 and a screw vacuum pump 10.

[0033] The first pre-condenser 1 and the second pre-condenser 2 are respectively connected to the refrigerant insulation tank 6 via the refrigerant circulation pump 29. The refrigerant insulation tank 6 is connected to the refrigeration unit 7. The refrigeration unit 7 includes a third condenser 23, an evaporator 24, a screw compressor 25, and an oil-gas separator 26.

[0034] The inlet and outlet of the dual parallel pre-cooled condenser are also connected to a bypass pipe 8, which is connected to the gas inlet and outlet of the first pre-condenser 1 and the second pre-condenser 2, respectively. A bypass valve 8.1 is installed on the bypass pipe 8. The bypass pipe 8 is used to bypass water vapor gas around the dual parallel pre-cooled condenser during the initial stage when the system pressure is high, preventing a large amount of water vapor from freezing and clogging the condenser, and enabling the vacuum reaction tower to quickly reach a high vacuum.

[0035] The Roots vacuum pump 9 is connected to the dual parallel pre-cryogenic condenser via a primary pressure transmitter 11 and a primary temperature transmitter 12. The Roots vacuum pump 9 is connected to the screw vacuum pump 10 via a secondary pressure transmitter 13, a check valve 16, and a secondary temperature transmitter 14. The screw vacuum pump 10 is connected to the outlet via a tertiary pressure transmitter 17 and a tertiary temperature transmitter 18, the latter being the exhaust temperature transmitter. The Roots vacuum pump 9 is connected to a cooling water switch valve 22 via a Roots pump cooling water valve 15, and the screw vacuum pump 10 is connected to the cooling water switch valve 22 via a screw pump cooling water valve 19. The cooling water switch valve 22 is connected to the inlet. A cooling water flow meter 20 is installed on the pipeline connecting the cooling water switch valve 22 to the Roots pump cooling water valve 15 and the screw pump cooling water valve 19. The outlet pipe of the screw vacuum pump 10 is connected to a silencer 21. The silencer 21 is provided with a silencer exhaust port 21.1 and a drain port. A silencer drain valve 21.2 is provided at the drain port.

[0036] The refrigerant circulation pump 29 is connected to the third condenser 23, the third condenser 23 is connected to the evaporator 24, the chilled water inlet of the evaporator 24 is connected to the screw compressor 25, the screw compressor 25 is connected to the oil-gas separator 26, and the chilled water outlet of the evaporator 24 is connected to the discharge port of the first pre-condenser 1 and the second pre-condenser 2. A four-stage temperature transmitter 27 is provided on the pipeline connecting the refrigerant circulation pump 29 and the third condenser 23, and a five-stage temperature transmitter 28 is provided on the pipeline connecting the first pre-condenser 1 and the second pre-condenser 2 and the evaporator 24. The refrigerant circulation pump 29 is connected to the refrigerant insulation tank 6 via the expansion joint 30 and the filter 31. The upper part of the refrigerant insulation tank 6 is provided with a refrigerant return port 6.1, a refrigerant replenishment port 6.3 and an overflow port 6.6. The lower part of the refrigerant insulation tank 6 is provided with a refrigerant outlet 6.2 and a vent port 6.5. The top surface of the refrigerant insulation tank 6 is provided with a vent 6.4 and an inspection and maintenance port 6.7. The refrigerant return port 6.1 of the refrigerant insulation tank 6 is connected to a dual parallel pre-cooled condenser. The refrigerant outlet 6.2 of the refrigerant insulation tank 6 is connected to the filter 31 via a pneumatic ball valve.

[0037] The muffler exhaust port 21.1 of the muffler 21 can also be connected to a tail gas treatment device for further treatment of the tail gas discharged from the screw vacuum pump to ensure that the emission meets the standards. The tail gas treatment device can be configured together with the vacuum unit or not, and the exhaust gas of the vacuum unit can be directly connected to the tail gas treatment device of the chemical plant's large system.

[0038] This embodiment of a duplex stainless steel vacuum unit system with low-temperature condensation capture also includes an intelligent control system for monitoring the entire system. The control system includes an electrical control cabinet 32, which is electrically connected to the main inlet valve, the refrigeration unit, the dual parallel pre-low-temperature condensers, the Roots vacuum pump, the screw vacuum pump, and the exhaust gas treatment device. It is used to monitor the operating parameters of the entire unit and realize automatic control. The condensate collection and discharge ports of the dual parallel pre-cooled condensers are equipped with level transmitters and automatic drain valves; the transmitter signals of all level transmitters, pressure transmitters, and temperature transmitters, as well as all valves, are connected to the control system.

[0039] In this embodiment, the main flow-through components of the dual parallel pre-cooled condenser, the Roots vacuum pump 9, and the screw vacuum pump 10 are all made of duplex stainless steel. The duplex stainless steel is of grades S32205 and S32507, and the phase ratio of ferrite to austenite in its metallographic structure is approximately 50:50.

[0040] In this embodiment, the dual parallel pre-cooled condensers are vertically arranged and installed. The condensers contain high-efficiency heat exchange tube bundles, and their cooling medium is a low-temperature refrigerant output from the low-temperature refrigeration unit. The refrigerant can be a calcium chloride aqueous solution, propylene glycol aqueous solution, trichlorotrifluoroethane, or other media. The operating temperature range is -50℃ to -10℃. The refrigerant (coolant) flows through the tube side of the condenser, while the process gas flows through the shell side. The coolant flows from bottom to top, and the process gas flows from top to bottom, in the opposite direction to the coolant, achieving better condensation. An air inlet is located at the bottom side of the condenser shell and connects to the main inlet valve. A condensate collection and discharge port is located on the other side of the bottom. An air outlet is located on the upper part of the side wall and connects to the main inlet valve of the Roots screw vacuum unit.

[0041] In this embodiment, the rotor profile of the Roots vacuum pump 9 is a brand-new "three-lobe" profile, and it has undergone high-precision dynamic balancing correction; the screw rotor of the screw vacuum pump adopts a "three-segment variable pitch double involute profile". The rotors of the Roots vacuum pump and the screw vacuum pump are made of duplex stainless steel of grades S32205 and S32507.

[0042] In this embodiment, the control logic of the control system includes: Based on the reading of the system inlet pressure transmitter, the bypass valve is automatically controlled to open and close: when the pressure is higher than the set value, the bypass valve is opened; when the pressure is lower than the set value, the bypass valve is closed. Based on the signal from the level transmitter installed on the side of the collection tank, the opening and closing of the automatic drain valve is automatically controlled to achieve timed discharge of condensate. Based on the reading difference between the primary and secondary pressure transmitters, the speed of the Roots vacuum pump is automatically controlled to achieve power matching and energy-saving operation between the Roots vacuum pump and the screw vacuum pump. Monitor all temperature and pressure parameters, and execute an automatic shutdown protection program in case of abnormal conditions such as over-temperature or over-pressure.

[0043] Working principle: The core process of this utility model is as follows: the gas to be pumped enters the main inlet valve from the vacuum reaction tower at the customer's site, and then enters one of the two parallel pre-condensers, with one pre-condenser in use and the other on standby.

[0044] The dual parallel condensers are typically vertically arranged. The low-temperature refrigerant flowing inside (such as ethylene glycol-water refrigerant, maintained at approximately -45°C) exchanges heat with the chemical gas through heat exchange tubes. Most of the condensable vapors in the gas (such as water vapor, acetone, ethanol, and strongly acidic media) are condensed into liquid here and fall to the bottom of the condenser by gravity. A level transmitter Y, located on the side of the storage tank below the dual parallel pre-condenser, monitors the liquid level inside the tank. When the level reaches a high level, the control system issues a command to open the automatic drain valve, discharging the condensate to an external collection tank. The dried, low-temperature gas, after deep condensation and dehumidification, is then led out from the outlet on the side wall of the dual parallel pre-condenser. Additional explanation: The use of two parallel condensers is necessary in certain harsh operating conditions where the medium is not liquid but rather forms ice crystals that cover the condenser tubes. When the ice crystals on the condenser tubes reach a certain thickness, they will affect the condenser's condensation efficiency and the flow conductance of the processed medium, impacting the system's vacuum level and pumping capacity. Therefore, switching between the two condensers is necessary to achieve continuous operation of the vacuum processing unit. The condensate ice crystals on the heat exchange tubes can be melted through various methods, including infrared heating, externally injected steam heating, and injecting hot water into the condenser tubes.

[0045] The dried gas, after being condensed in the condenser, enters the Roots vacuum pump in the vacuum system. The pump casing, end covers, and rotor of this Roots vacuum pump are all precision cast and machined from duplex stainless steel (S32205), and its three-lobe rotor profile effectively reduces airflow pulsation and noise. The Roots vacuum pump pressurizes the gas, and its outlet pressure is monitored by a two-stage pressure transmitter.

[0046] Next, the gas is fed into a screw vacuum pump. This screw vacuum pump is also made of duplex stainless steel, and its core screw rotor is coated with a tungsten carbide wear-resistant layer, greatly enhancing the rotor's wear resistance and anti-galling capabilities. As a backing pump, the screw vacuum pump compresses the gas to above atmospheric pressure, and finally discharges it through an exhaust silencer to the factory's exhaust gas treatment system (which typically involves sequential condensation separation and activated carbon adsorption) before releasing it into the atmosphere. The exhaust temperature and pressure are monitored by temperature transmitter T3 and pressure transmitter Pt3, respectively.

[0047] During the initial startup of the vacuum unit, the pressure of the system being evacuated is relatively high. If the pre-cryogenic condenser is turned on at this time, a large amount of gas may condense instantly, potentially causing ice blockage in the condenser tubes. Therefore, the control system determines the appropriate level of pressure based on the reading of the primary pressure transmitter P1: when P1 > 5000 Pa, the bypass valve is opened, allowing most of the gas to enter the vacuum pump unit directly through the bypass pipeline (bypassing the pre-condenser) for rapid pre-vacuuming; when the system pressure drops to P1 < 1000 Pa, the bypass valve is closed, and all gas flows through the pre-cryogenic condenser for deep condensation.

[0048] Throughout the process, the control system collects real-time signals from all transmitters, including P1, Pt1, Pt2, Pt3, Tt1, Tt2, Tt3, Tt4, Tt5, and Y, as well as parameters such as the operating current of the screw compressor, Roots vacuum pump, and screw vacuum pump. The system then executes the aforementioned automatic control logic through a built-in PLC program and displays real-time operating conditions, alarm information, and historical data on the human-machine interface.

[0049] Work process: When the system starts up, if the primary pressure transmitter detects a high pressure (e.g., > 5000 Pa), the intelligent control system will open the bypass valve, allowing most of the gas to bypass the condenser and directly enter the pump unit, achieving rapid vacuuming. When the pressure drops to the set value (e.g., < 1000 Pa), the bypass valve closes, and all gas flows through the condenser for deep condensation. Simultaneously, the system controls the opening and closing of the automatic drain valve based on the signal from the level transmitter, achieving automatic discharge of condensate. The entire process is highly automated and operates stably and reliably.

[0050] This invention effectively solves the problems of corrosion, pollution, and condensate treatment faced by traditional vacuum units under harsh operating conditions through specific structural design, material selection, and system integration, and provides a high-performance, high-reliability vacuum solution.

[0051] The design concept of this utility model is to utilize the condenser of a cryogenic freezer to condense and capture the highly corrosive chemical gases released from the reaction tower of a chemical plant. Assuming a capture efficiency of 90%, the vacuum pump unit only needs to pump the remaining 10% of the uncondensed gas. Therefore, the vacuum pump unit is much smaller and consumes less energy. The energy consumption of the associated refrigeration compressor is far lower than that required for a vacuum pump unit to remove 90% of the gas. Thus, this novel design achieves better energy-saving results. For the vacuum pump unit, the less corrosive gas present, the longer its service life will be. Compared to using a small vacuum unit with cryogenic freezing to capture the same gas volume, using a large vacuum unit can save 70% of energy, and the latter requires less investment and occupies less space.

[0052] This utility model discloses a duplex stainless steel vacuum unit system with cryogenic condensation trapping, comprising an inlet main valve, a double parallel pre-cryogenic condenser, a Roots vacuum pump, a screw vacuum pump, and an exhaust gas treatment device connected sequentially via pipelines, and integrating a cryogenic refrigeration unit and an intelligent control system. Its innovations lie in: the core flow-through components of the system are made of corrosion-resistant duplex stainless steel; a vertically arranged double parallel shell-and-tube cryogenic condenser is installed at the inlet of the vacuum pump unit, which can pre-condense and separate condensable and highly corrosive vapors; and the series combination of a Roots vacuum pump and a screw vacuum pump achieves efficient pumping over a wide pressure range. This utility model features a compact design, strong corrosion resistance, and good anti-pollution capability, making it particularly suitable for harsh operating conditions involving highly corrosive and easily condensable media, such as in the chemical, pharmaceutical, and lithium battery industries, and offers advantages such as reliable operation and long service life.

[0053] This invention is particularly suitable for harsh working conditions such as chemical, pharmaceutical, and lithium battery industries where there are highly corrosive and easily condensable media. It has the advantages of strong corrosion resistance, pollution resistance, high ultimate vacuum, high degree of automation, and reliable operation. This invention can also be extended to the oil refining industry, which needs to process large amounts of condensable chemical gases. By using a condenser to capture large amounts of condensable chemical gases, it can achieve the purpose of processing large volumes of air with a small vacuum pump set.

[0054] The above are merely specific application examples of this utility model and do not constitute any limitation on the scope of protection of this utility model. All technical solutions formed by equivalent transformations or equivalent substitutions fall within the scope of protection of this utility model.

Claims

1. A duplex stainless steel vacuum package system with cryocondensation trapping, characterized by: It includes a dual parallel pre-cooled condenser, a vacuum unit (5) and a refrigeration unit (7). The dual parallel pre-cooled condenser includes a first pre-cooler (1) and a second pre-cooler (2). The vacuum unit (5) and the refrigeration unit (7) are respectively connected to the dual parallel pre-cooled condenser. The refrigeration unit (7) provides a cold source for the dual parallel pre-cooled condenser, forming the refrigeration system of the vacuum unit (5). The inlet of the first pre-condenser (1) is connected to the first inlet main valve (1.1), and the first pre-condenser (1) is also connected to the first steam purge port (1.2). The inlet of the second pre-condenser (2) is connected to the second inlet main valve (2.1). The outlets of the first pre-condenser (1) and the second pre-condenser (2) are respectively connected to the liquid collection tank (4), and the liquid collection tank (4) is connected to the liquid level transmitter (4.1). The vacuum unit (5) is connected to the outlet of the double parallel pre-low temperature condenser through the vacuum unit inlet valve (5.1). The vacuum unit (5) includes a Roots vacuum pump (9) and a screw vacuum pump (10). The Roots vacuum pump (9) is connected to the dual parallel pre-cryogenic condenser via a primary pressure transmitter (11) and a primary temperature transmitter (12). The Roots vacuum pump (9) is connected to the screw vacuum pump (10) via a secondary pressure transmitter (13), a check valve (16), and a secondary temperature transmitter (14). The screw vacuum pump (10) is connected to the outlet via a tertiary pressure transmitter (17) and a tertiary temperature transmitter (18). The Roots vacuum pump (9) is connected to a cooling water switch valve (22) via a Roots pump cooling water valve (15). The screw vacuum pump (10) is connected to a cooling water switch valve (22) via a screw pump cooling water valve (19). The cooling water switch valve (22) is connected to the inlet. The outlet via a screw vacuum pump (10) is connected to a silencer (21). The first pre-condenser (1) and the second pre-condenser (2) are respectively connected to the refrigerant insulation tank (6) via the refrigerant circulation pump (29). The refrigerant insulation tank (6) is connected to the refrigeration unit (7). The refrigeration unit (7) includes a third condenser (23), an evaporator (24), a screw compressor (25), and an oil-gas separator (26). The refrigerant circulation pump (29) is connected to the third condenser (23), the third condenser (23) is connected to the evaporator (24), the chilled water inlet of the evaporator (24) is connected to the screw compressor (25), the screw compressor (25) is connected to the oil-gas separator (26), and the chilled water outlet of the evaporator (24) is connected to the discharge ports of the first pre-condenser (1) and the second pre-condenser (2). A four-stage temperature transmitter (27) is provided on the pipeline connecting the refrigerant circulation pump (29) and the third condenser (23), and a five-stage temperature transmitter (28) is provided on the pipeline connecting the first pre-condenser (1) and the second pre-condenser (2) and the evaporator (24).

2. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: The second pre-condenser (2) also includes a second steam purge port (2.2); the first inlet main valve (1.1) and the second inlet main valve (2.1) are connected in sequence by pipelines, and the first inlet main valve (1.1) and the second inlet main valve (2.1) are respectively connected to the main air inlet (3), which is connected to the on-site chemical reaction device.

3. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: The liquid collection tank (4) is connected to the third steam purging port (4.2), and the bottom of the liquid collection tank (4) is provided with a liquid collection tank drain port (4.3).

4. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: The inlet and outlet of the dual parallel pre-cooled condenser are also connected to a bypass pipe (8), which is connected to the gas inlet and outlet of the first pre-condenser (1) and the second pre-condenser (2), respectively; a bypass valve (8.1) is provided on the bypass pipe (8).

5. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: A cooling water flow meter (20) is installed on the pipeline connecting the cooling water switch valve (22) to the Roots pump cooling water valve (15) and the screw pump cooling water valve (19).

6. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: The muffler (21) is provided with a muffler exhaust port (21.1) and a drain port, and a muffler drain valve (21.2) is provided at the drain port.

7. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: The refrigerant circulation pump (29) is connected to the refrigerant insulation tank (6) via an expansion joint (30) and a filter (31).

8. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: The upper part of the cryogenic insulated tank (6) is provided with a cryogenic return port (6.1), a replenishment port (6.3) and an overflow port (6.6). The lower part of the cryogenic insulated tank (6) is provided with a cryogenic outlet (6.2) and a vent port (6.5). The top surface of the cryogenic insulated tank (6) is provided with a vent (6.4) and an inspection and maintenance port (6.7). The cryogenic return port (6.1) of the cryogenic insulated tank (6) is connected to a dual parallel pre-cooled condenser. The cryogenic outlet (6.2) of the cryogenic insulated tank (6) is connected to a filter (31) via a pneumatic ball valve.

9. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 6 wherein: The muffler (21) has its exhaust port (21.1) connected to the exhaust gas treatment device. The exhaust gas treatment device can be configured together with the vacuum unit, or the exhaust gas from the vacuum unit can be directly connected to the exhaust gas treatment device of the large chemical plant system.

10. A duplex stainless steel vacuum unit system with low temperature condensing trap as claimed in claim 1, wherein: It also includes an intelligent control system that monitors the entire system. The control system includes an electrical control cabinet (32), which is electrically connected to the first inlet main valve (1.1), the second inlet main valve (2.1), the refrigeration unit, the dual parallel pre-cooled condenser, the Roots vacuum pump (9), the screw vacuum pump (10), and various transmitters and valves. It is used to monitor the operating parameters of the entire unit and realize automatic control.

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