Electronic special gas production refrigerant total recovery system and method based on liquid nitrogen cryogenic cooling and application of electronic special gas production refrigerant total recovery system and method based on liquid nitrogen cryogenic cooling

Abstract

The invention discloses an electronic special gas production refrigerant total recovery system and method based on liquid nitrogen deep cooling and application, and belongs to the technical field of special gas purification. The system comprises a liquid storage tank, a refrigerant condenser, a gas-liquid separation tank and a jacket condenser; the method comprises the steps of primary recovery, deep recovery, residual cold utilization and discharge of condensed refrigerants into the liquid storage tank. According to the liquid nitrogen cryogenic electronic special gas production refrigerant total recovery system and method, refrigerant discharge can be reduced, the refrigerant use cost can be saved, environmental pollution caused by refrigerant discharge can be reduced, stable operation of a refrigeration system can be maintained, and it is guaranteed that the refrigerant gasified by a rectification system can return to a refrigerant condenser.

Description

Technical Field

[0001] The present invention belongs to the technical field of special gas purification, and relates to a full refrigerant recovery system, method and application for the production of electronic special gases based on liquid nitrogen cryogenics. Background Art

[0002] In the distillation and purification process of electronic specialty gases such as silane, a low-temperature environment of -30°C to -80°C is required to separate impurities. Currently, fluorinated hydrocarbon refrigerant circulation systems are widely used. With the Kigali Amendment's upgraded control of hydrofluorocarbons, existing technologies face two major technical bottlenecks: (1) When non-condensable gases (N2 / O2) accumulate and cause system pressure to rise, the traditional direct discharge method causes an annual refrigerant loss of 15-20%; (2) The GWP value of refrigerants such as R23 exceeds 12,000, and direct discharge will pose a significant environmental risk.

[0003] According to actual measurements, in the traditional silane distillation system, 3.5-4.2m3 of non-condensable gas is generated per ton of silane processed. 3 The refrigerant content in the exhaust gas is as high as 38-42 vol%, and the system pressure fluctuation range is ±0.15 MPa.

[0004] Therefore, how to develop a full recovery system and method for electronic special gas production refrigerant based on liquid nitrogen deep cooling that maintains efficient refrigeration of the refrigerant, reduces or eliminates external emissions, and stabilizes silane distillation and purification operations is an urgent problem that technicians in this field need to solve. Summary of the Invention

[0005] In view of this, the present invention provides a full refrigerant recovery system, method and application for electronic special gas production based on liquid nitrogen cryogenics.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A full refrigerant recovery system for electronic specialty gas production based on liquid nitrogen cryogenics, including a liquid storage tank, a refrigerant condenser, a gas-liquid separation tank, and a jacketed condenser;

[0008] The gas-liquid separation tank includes a heat exchanger and a storage tank. The heat exchanger is arranged on the top of the storage tank and is an integrated structure. The bottom air inlet of the heat exchanger is connected to the top air outlet of the storage tank.

[0009] The tube-side discharge port of the refrigerant condenser is connected to the tube-side feed port of the jacketed condenser via a pipeline, the tube-side discharge port of the jacketed condenser is connected to the feed port on the upper side wall of the storage tank via a pipeline, the discharge port at the bottom of the storage tank is connected to the feed port of the liquid storage tank via a pipeline, and the discharge port of the liquid storage tank is connected to the tube-side of the refrigerant condenser via a pipeline;

[0010] The lower feed port of the shell side wall of the heat exchanger is connected to a liquid nitrogen inlet pipe, the upper air outlet of the shell side wall of the heat exchanger is connected to the jacket air inlet of the jacketed condenser via a pipeline, the jacket air outlet of the jacketed condenser is connected to a nitrogen outlet pipe, and the top air outlet of the tube side of the heat exchanger is connected to a vent pipe.

[0011] Furthermore, it also includes a first pressure transmitter to a third pressure transmitter, a first liquid level transmitter to a second liquid level transmitter, and a first control valve to a fifth control valve;

[0012] A first pressure transmitter is provided on the pipe side of the refrigerant condenser, a second control valve is provided on the pipe connecting the refrigerant condenser and the jacket condenser, and the first pressure transmitter is interlocked with the second control valve;

[0013] The nitrogen outlet pipe is provided with a second pressure transmitter and a fourth control valve in sequence, and the second pressure transmitter is interlocked with the fourth control valve;

[0014] The storage tank is provided with a third pressure transmitter, the vent pipe is provided with a fifth control valve, and the third pressure transmitter is interlocked with the fifth control valve;

[0015] A second liquid level transmitter is provided on the shell side of the heat exchanger, a third control valve is provided on the liquid nitrogen inlet pipe, and the second liquid level transmitter is interlocked with the third control valve;

[0016] The storage tank is provided with a first liquid level transmitter, and a first control valve is provided on the pipeline connecting the storage tank and the liquid storage tank. The first liquid level transmitter is interlocked with the first control valve.

[0017] Furthermore, the first to fifth control valves are pneumatic shut-off valves.

[0018] The present invention also provides a method for fully recovering refrigerant in the production of electronic specialty gases based on liquid nitrogen cryogenics, comprising the following steps:

[0019] (1) Primary recovery: The electronic special gas production refrigerant full recovery system based on liquid nitrogen cryogenics is used. The condenser is introduced into the shell side of the refrigerant condenser. The refrigerant containing non-condensable gas accumulates in the tube side of the refrigerant condenser. The first pressure transmitter is interlocked with the second control valve. When the operating pressure of the tube side of the refrigerant condenser is greater than a certain value, the second control valve is opened. The response time is less than 0.5s. The refrigerant containing non-condensable gas first enters the tube side of the jacketed condenser for preliminary cooling, and then enters the storage tank of the gas-liquid separation tank.

[0020] (2) Deep recovery: The refrigerant containing non-condensable gas enters the storage tank of the gas-liquid separation tank, and liquid nitrogen is introduced into the shell side of the heat exchanger through the liquid nitrogen inlet pipe. The second liquid level transmitter is interlocked with the third control valve. When the shell side liquid level of the heat exchanger is lower than a certain value, the third control valve is opened, and the response time is less than 0.5s. The condensed refrigerant is discharged into the liquid storage tank. Under the action of liquid nitrogen, the refrigerant in the non-condensable gas is liquefied and flows to the bottom storage tank. The gas phase moves upward and enters the pipe side of the heat exchanger. The third pressure transmitter is interlocked with the fifth control valve. When the operating pressure of the storage tank is greater than a certain value, the fifth control valve is opened, and the response time is less than 0.5s. The non-condensable gas is discharged at a high position through the vent pipe;

[0021] (3) Utilization of residual cooling: After the liquid nitrogen passes through the shell side of the heat exchanger of the gas-liquid separator, the gaseous low-temperature nitrogen enters the jacket of the jacketed condenser, pre-cooling the refrigerant containing non-condensable gas in the tube side of the jacketed condenser. The second pressure transmitter is interlocked with the fourth control valve. When the operating pressure of the nitrogen outlet pipe is greater than a certain value, the fourth control valve opens with a response time of less than 0.5s, and the nitrogen is discharged through the nitrogen outlet pipe.

[0022] (4) The first liquid level transmitter is interlocked with the first control valve. When the liquid level of the storage tank is greater than a certain value, the first control valve opens with a response time of <0.5s. The condensed refrigerant is discharged into the liquid storage tank, and the refrigerant in the liquid storage tank returns to the refrigerant condenser and continues to be used for purification of the electronic special gas distillation tower.

[0023] Furthermore, in step (1), the operating pressure of the tube side of the refrigerant condenser is greater than 1.5 MPa, and the second control valve is opened;

[0024] In step (2), the shell side liquid level of the heat exchanger is lower than 500 mm, and the third control valve is opened;

[0025] In step (3), the operating pressure of the nitrogen outlet pipe is greater than 0.6 MPa, and the fourth control valve is opened; the operating pressure of the storage tank is greater than 1.2 MPaG, and the fifth control valve is opened;

[0026] In step (4), the liquid level of the storage tank is greater than 2500 mm, and the first control valve is opened.

[0027] Furthermore, in step (1), the refrigerant includes one or a mixture of C2H4, R23, R508B, R170, liquid ammonia or R744.

[0028] Furthermore, in step (1), the condensing agent includes R22, R290, R410a or R32.

[0029] The present invention also provides the application of the electronic special gas production refrigerant full recovery system based on liquid nitrogen cryogenics or the electronic special gas production refrigerant full recovery method based on liquid nitrogen cryogenics in recovering the refrigerant after the electronic special gas is produced, wherein the electronic special gas is silane, disilane, monochlorotrihydrosilane, dichlorodihydrosilane, trimethylsilylamine, phosphine, nitrogen trifluoride, carbon tetrafluoride, silicon tetrafluoride, diborane or ammonia.

[0030] The beneficial effects of the present invention are as follows: the liquid nitrogen cryogenically cooled electronic special gas production refrigerant full recovery system and method of the present invention can reduce refrigerant emissions, save refrigerant usage costs, reduce environmental pollution caused by refrigerant emissions, maintain stable operation of the refrigeration system, and ensure that the refrigerant vaporized in the distillation system can be returned to the refrigerant condenser.

[0031] The liquid nitrogen cryogenic electronic specialty gas production refrigerant full recovery system of the present invention is a three-stage recovery system for refrigerants in the distillation and purification process of electronic specialty gases such as silane, which is of great significance for energy saving, consumption reduction and stable operation of the production system.

[0032] After the liquid nitrogen passes through the shell side of the heat exchanger of the gas-liquid separation tank, the gaseous low-temperature nitrogen enters the jacket of the jacketed condenser, precools the refrigerant containing non-condensable gas in the tube side of the jacketed condenser, establishes a cold energy cascade utilization system, and increases the liquid nitrogen cold energy utilization rate to 92%.

[0033] The fifth control valve of the present invention is normally closed, which effectively reduces the refrigerant discharge by interlocking the gas-liquid separation tank pressure. At the same time, a flow limiting orifice is added to prevent a large amount of gas from being vented at the moment of valve opening, causing the refrigerant to be discharged.

[0034] In the present invention, after the liquid nitrogen is gasified by the heat exchanger, the temperature is still relatively low, and the residual cooling is fully utilized to pre-cool the refrigerant entering the jacketed condenser, thereby saving energy consumption.

[0035] The gas-liquid separation tank of the present invention realizes cooling and separation functions simultaneously, and is an integrated device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention provides a full refrigerant recovery system for producing electronic special gases based on liquid nitrogen cryogenics.

[0037] Among them, 1-liquid storage tank, 2-refrigerant condenser, 3-gas-liquid separation tank, 4-jacketed condenser, 5-heat exchanger, 6-storage tank, 11-first control valve, 12-second control valve, 13-third control valve, 14-fourth control valve, 15-fifth control valve, 21-first pressure transmitter, 22-second pressure transmitter, 23-third pressure transmitter, 31-first liquid level transmitter, 32-second liquid level transmitter. DETAILED DESCRIPTION

[0038] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0039] The electronic specialty gas production refrigerant full recovery system based on liquid nitrogen cryogenics includes a liquid storage tank 1, a refrigerant condenser 2, a gas-liquid separation tank 3, and a jacket condenser 4;

[0040] The gas-liquid separation tank 3 includes a heat exchanger 5 and a storage tank 6. The heat exchanger 5 is arranged on the top of the storage tank 6 as an integrated structure. The bottom air inlet of the heat exchanger 5 is connected to the top air outlet of the storage tank 6.

[0041] The tube-side discharge port of the refrigerant condenser 2 is connected to the tube-side feed port of the jacketed condenser 4 via a pipeline, the tube-side discharge port of the jacketed condenser 4 is connected to the feed port on the upper side wall of the storage tank 6 via a pipeline, the discharge port at the bottom of the storage tank 6 is connected to the feed port of the liquid storage tank 1 via a pipeline, and the discharge port of the liquid storage tank 1 is connected to the tube-side of the refrigerant condenser 2 via a pipeline;

[0042] The lower feed port of the shell side wall of the heat exchanger 5 is connected to a liquid nitrogen inlet pipe, the upper air outlet of the shell side wall of the heat exchanger 5 is connected to the jacket air inlet of the jacketed condenser 4 through a pipeline, the jacket air outlet of the jacketed condenser 4 is connected to a nitrogen outlet pipe, and the top air outlet of the tube side of the heat exchanger 5 is connected to a vent pipe.

[0043] In one embodiment, the system further includes first to third pressure transmitters 21 to 23, first to second liquid level transmitters 31 to 32, and first to fifth control valves 11 to 15;

[0044] A first pressure transmitter 21 is provided on the pipe line of the refrigerant condenser 2, and a second control valve 12 is provided on the pipe connecting the refrigerant condenser 2 and the jacket condenser 4. The first pressure transmitter 21 is interlocked with the second control valve 12;

[0045] The nitrogen outlet pipe is provided with a second pressure transmitter 22 and a fourth control valve 14 in sequence, and the second pressure transmitter 22 is interlocked with the fourth control valve 14;

[0046] The storage tank 6 is provided with a third pressure transmitter 23, and the vent pipe is provided with a fifth control valve 15. The third pressure transmitter 23 is interlocked with the fifth control valve 15;

[0047] The shell side of the heat exchanger 5 is provided with a second liquid level transmitter 32, and the liquid nitrogen inlet pipe is provided with a third control valve 13. The second liquid level transmitter 32 is interlocked with the third control valve 13;

[0048] The storage tank 6 is provided with a first liquid level transmitter 31 , and the pipeline connecting the storage tank 6 and the liquid storage tank 1 is provided with a first control valve 11 . The first liquid level transmitter 31 is interlocked with the first control valve 11 .

[0049] In one embodiment, the first to fifth control valves 11 to 15 are pneumatic shut-off valves.

[0050] Example 1

[0051] A method for fully recovering refrigerant from silane production based on liquid nitrogen cryogenics includes the following steps:

[0052] (1) Primary recovery: The present invention adopts a silane production refrigerant full recovery system based on liquid nitrogen cryogenics. The refrigerant (R22) is introduced into the shell side of the refrigerant condenser 2. Non-condensable gas containing refrigerant (R23) accumulates in the tube side of the refrigerant condenser 2. The first pressure transmitter 21 is interlocked with the second control valve 12. The operating pressure of the tube side of the refrigerant condenser 2 is greater than 1.5 MPa. The second control valve 12 is opened with a response time of less than 0.5 s. The refrigerant containing non-condensable gas first enters the tube side of the jacketed condenser 4 for preliminary cooling. The jacketed condenser 4 is a jacketed tube structure. Then, the refrigerant enters the storage tank 6 of the gas-liquid separation tank 3.

[0053] (2) Deep recovery: The refrigerant containing non-condensable gas enters the storage tank 6 of the gas-liquid separator 3, and liquid nitrogen is introduced into the shell side of the heat exchanger 5 through the liquid nitrogen inlet pipe. The second liquid level transmitter 32 is interlocked with the third control valve 13. The shell side liquid level of the heat exchanger 5 is lower than 500 mm. The third control valve 13 is opened with a response time of less than 0.5 s. The condensed refrigerant is discharged into the liquid storage tank 1. Under the action of liquid nitrogen, the refrigerant in the non-condensable gas is liquefied and flows to the bottom storage tank 6. The gas phase enters the pipe side of the heat exchanger 5 upward. The third pressure transmitter 23 is interlocked with the fifth control valve 15. The operating pressure of the storage tank 6 is greater than 1.2 MPaG. The fifth control valve 15 is opened with a response time of less than 0.5 s. The non-condensable gas is discharged at a high position through the vent pipe.

[0054] (3) Utilization of residual cooling: After the liquid nitrogen passes through the shell side of the heat exchanger 5 of the gas-liquid separator 3, the gaseous low-temperature nitrogen enters the jacket of the jacketed condenser 4, and pre-cools the refrigerant containing non-condensable gas in the pipe side of the jacketed condenser 4. The second pressure transmitter 22 is interlocked with the fourth control valve 14. The operating pressure of the nitrogen outlet pipe is greater than 0.6 MPa. The fourth control valve 14 is opened with a response time of less than 0.5 s. The nitrogen is discharged through the nitrogen outlet pipe and the nitrogen is recovered.

[0055] (4) The first liquid level transmitter 31 is interlocked with the first control valve 11. When the liquid level of the storage tank 6 is greater than 2500 mm, the first control valve 11 opens with a response time of less than 0.5 s. The condensed refrigerant is discharged into the liquid storage tank 1. The refrigerant in the liquid storage tank 1 returns to the refrigerant condenser 2 and continues to be used for purification in the silane distillation tower.

[0056] Vent pipe discharge port detection: R230.05vol%;

[0057] Annual operation and maintenance costs: RMB 95,000.

[0058] Comparative Example 1

[0059] Using traditional direct discharge method:

[0060] Detection of gas composition at the exhaust port: R2341.7vol%;

[0061] Annual operation and maintenance costs: RMB 820,000.

[0062] Table 1

[0063]

[0064] Industrial verification shows that the system of the present invention realizes:

[0065] 1. Refrigerant recovery rate ≥99.2% (GC-MS detection)

[0066] 2. Improved system operation stability:

[0067] Pressure fluctuation amplitude is reduced by 86%;

[0068] The temperature gradient deviation of the distillation tower is less than 0.5℃;

[0069] 3. Environmental benefits:

[0070] A single unit can reduce carbon emissions by 3,800 tons per year;

[0071] Refrigerant refill costs decreased by 93%.

[0072] The disclosed embodiments are described to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. A refrigerant recovery system for electronic specialty gas production based on liquid nitrogen cryogenics, characterized in that: Including liquid storage tank, refrigerant condenser, gas-liquid separation tank and jacketed condenser; The gas-liquid separation tank includes a heat exchanger and a storage tank. The heat exchanger is arranged on the top of the storage tank and is an integrated structure. The bottom air inlet of the heat exchanger is connected to the top air outlet of the storage tank. The tube-side discharge port of the refrigerant condenser is connected to the tube-side feed port of the jacketed condenser via a pipeline, the tube-side discharge port of the jacketed condenser is connected to the feed port on the upper side wall of the storage tank via a pipeline, the discharge port at the bottom of the storage tank is connected to the feed port of the liquid storage tank via a pipeline, and the discharge port of the liquid storage tank is connected to the tube-side of the refrigerant condenser via a pipeline; The lower feed port of the shell side wall of the heat exchanger is connected to a liquid nitrogen inlet pipe, the upper air outlet of the shell side wall of the heat exchanger is connected to the jacket air inlet of the jacketed condenser via a pipeline, the jacket air outlet of the jacketed condenser is connected to a nitrogen outlet pipe, and the top air outlet of the tube side of the heat exchanger is connected to a vent pipe.

2. The refrigerant recovery system for producing electronic specialty gases based on liquid nitrogen cryogenics according to claim 1 is characterized in that: It also includes a first pressure transmitter to a third pressure transmitter, a first liquid level transmitter to a second liquid level transmitter, and a first control valve to a fifth control valve; A first pressure transmitter is provided on the pipe side of the refrigerant condenser, a second control valve is provided on the pipe connecting the refrigerant condenser and the jacket condenser, and the first pressure transmitter is interlocked with the second control valve; The nitrogen outlet pipe is provided with a second pressure transmitter and a fourth control valve in sequence, and the second pressure transmitter is interlocked with the fourth control valve; The storage tank is provided with a third pressure transmitter, the vent pipe is provided with a fifth control valve, and the third pressure transmitter is interlocked with the fifth control valve; A second liquid level transmitter is provided on the shell side of the heat exchanger, a third control valve is provided on the liquid nitrogen inlet pipe, and the second liquid level transmitter is interlocked with the third control valve; The storage tank is provided with a first liquid level transmitter, and a first control valve is provided on the pipeline connecting the storage tank and the liquid storage tank. The first liquid level transmitter is interlocked with the first control valve.

3. The refrigerant recovery system for producing electronic specialty gases based on liquid nitrogen cryogenics according to claim 1 is characterized in that: The first to fifth control valves are pneumatic shut-off valves.

4. A method for fully recovering refrigerant in the production of electronic specialty gases based on liquid nitrogen cryogenics, characterized in that: The following steps are involved: (1) Primary recovery: adopting the full refrigerant recovery system for producing electronic special gases based on liquid nitrogen cryogenics as described in any one of claims 1 to 3, introducing condensing agent into the shell side of the refrigerant condenser, accumulating refrigerant containing non-condensable gas in the tube side of the refrigerant condenser, interlocking the first pressure transmitter with the second control valve, and opening the second control valve when the operating pressure of the tube side of the refrigerant condenser is greater than a certain value, with a response time of less than 0.5s, and the refrigerant containing non-condensable gas first entering the tube side of the jacketed condenser for preliminary cooling, and then entering the storage tank of the gas-liquid separator; (2) Deep recovery: The refrigerant containing non-condensable gas enters the storage tank of the gas-liquid separation tank, and liquid nitrogen is introduced into the shell side of the heat exchanger through the liquid nitrogen inlet pipe. The second liquid level transmitter is interlocked with the third control valve. When the shell side liquid level of the heat exchanger is lower than a certain value, the third control valve is opened, and the response time is less than 0.5s. The condensed refrigerant is discharged into the liquid storage tank. Under the action of liquid nitrogen, the refrigerant in the non-condensable gas is liquefied and flows to the bottom storage tank. The gas phase enters the pipe side of the heat exchanger upward. The third pressure transmitter is interlocked with the fifth control valve. When the operating pressure of the storage tank is greater than a certain value, the fifth control valve is opened, and the response time is less than 0.5s. The non-condensable gas is discharged at a high position through the vent pipe; (3) Utilization of residual cooling: After the liquid nitrogen passes through the shell side of the heat exchanger of the gas-liquid separator, the gaseous low-temperature nitrogen enters the jacket of the jacketed condenser, pre-cooling the refrigerant containing non-condensable gas in the tube side of the jacketed condenser. The second pressure transmitter is interlocked with the fourth control valve. When the operating pressure of the nitrogen outlet pipe is greater than a certain value, the fourth control valve opens with a response time of less than 0.5s, and the nitrogen is discharged through the nitrogen outlet pipe. (4) The first liquid level transmitter is interlocked with the first control valve. When the liquid level of the storage tank is greater than a certain value, the first control valve opens with a response time of <0.5s. The condensed refrigerant is discharged into the liquid storage tank, and the refrigerant in the liquid storage tank returns to the refrigerant condenser and continues to be used for purification of the electronic special gas distillation tower.

5. The method for fully recovering refrigerant in the production of electronic specialty gases based on liquid nitrogen cryogenics according to claim 4, characterized in that: In step (1), the operating pressure of the tube side of the refrigerant condenser is greater than 1.5 MPa, and the second control valve is opened; In step (2), the shell side liquid level of the heat exchanger is lower than 500 mm, and the third control valve is opened; In step (3), the operating pressure of the nitrogen outlet pipe is greater than 0.6 MPa, and the fourth control valve is opened; the operating pressure of the storage tank is greater than 1.2 MPaG, and the fifth control valve is opened; In step (4), the liquid level of the storage tank is greater than 2500 mm, and the first control valve is opened.

6. The method for fully recovering refrigerant in the production of electronic specialty gases based on liquid nitrogen cryogenics according to claim 4, characterized in that: In step (1), the refrigerant includes one or a mixture of C2H4, R23, R508B, R170, liquid ammonia or R744.

7. The method for fully recovering refrigerant in the production of electronic specialty gases based on liquid nitrogen cryogenics according to claim 4, characterized in that: In step (1), the condensing agent includes R22, R290, R410a or R32.

8. Application of the system for fully recovering refrigerant from the production of electronic special gases based on liquid nitrogen cryogenics according to any one of claims 1 to 3 or the method for fully recovering refrigerant from the production of electronic special gases based on liquid nitrogen cryogenics according to any one of claims 4 to 7 in recovering refrigerant after the production of electronic special gases, characterized in that: The electronic special gas is silane, disilane, monochlorotrihydrogen silicon, dichlorodihydrogen silicon, trimethylsilylamine, phosphine, nitrogen trifluoride, carbon tetrafluoride, silicon tetrafluoride, diborane or ammonia.

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