A mass spectrometer deep cooling device and refrigeration method thereof

Abstract

The present invention belongs to the technical field of mass spectrometry analysis, and specifically relates to a mass spectrometer cryogenic device and a refrigeration method thereof, comprising: a refrigeration main unit and a heat exchange box, wherein the refrigeration main unit and the heat exchange box are integrally connected; the refrigeration main unit comprises: a condenser, a compressor and a mixed working fluid storage tank; the compressor is provided with a mixed working fluid storage tank, and the condenser is arranged beside the compressor; the heat exchange box comprises: a flow pipe, a cold trap, a temperature sensor, a heat insulation layer, a solenoid valve interface and a cold trap connection end; the flow pipe is arranged on the outer wall of the lower section of the cold trap; the outer wall of the upper section of the cold trap is provided with a heat insulation layer; the solenoid valve interface is arranged at the upper end of the heat exchange box, and the temperature sensor is arranged at the cold trap; one end of the cold trap is connected to the cold trap connection end.

Description

Technical Field

[0001] The invention belongs to the technical field of mass spectrometry analysis, and in particular relates to a mass spectrometer cryogenic device and a refrigeration method thereof. Background Art

[0002] Uranium enrichment plants use gas isotope mass spectrometers to test product quality. The sampling system of the mass spectrometer usually has two cold traps, one for collecting residual samples in the sample storage tank during the analysis process, and the other for collecting sample impurities during the purification process of the standard and the sample to be tested. Generally, the two cold traps need to be placed in a steel insulation container, and liquid nitrogen is added to the container to freeze and collect the waste gas with the help of the low temperature environment caused by the liquid nitrogen. In addition, after the mass spectrometer sampling system reaches a high vacuum, the extremely low temperature cold trap acts as a "condensation pump" to further improve the vacuum degree of the sampling system. In theory, the lower the temperature, the better the vacuum degree. Because the mass spectrometer consumes a small amount of liquid nitrogen, the cost of producing liquid nitrogen is high, and there is a safety risk of being "scalded" by liquid nitrogen during use and transportation, it is urgent to design a small cryogenic device that uses only electricity as energy and uses single-stage compression refrigeration. The refrigeration temperature is close to liquid nitrogen, which can make the mass spectrometer run normally after using the cryogenic device to solve the problems in the prior art. Summary of the invention

[0003] The purpose of the present invention is to design a mass spectrometer cryogenic device and a refrigeration method thereof in view of the above-mentioned deficiencies in the prior art, so as to solve the technical problems in the prior art that the mass spectrometer uses liquid nitrogen to collect waste gas in a low-temperature environment and is prone to safety accidents and has excessively high production costs.

[0004] The technical solution of the present invention is:

[0005] A mass spectrometer cryogenic device comprises: a refrigeration main unit 1 and a heat exchange box 2, wherein the refrigeration main unit 1 and the heat exchange box 2 are integrally connected; the refrigeration main unit 1 comprises: a condenser 8, a compressor 9 and a mixed working fluid storage tank 10; the compressor 9 is provided with the mixed working fluid storage tank 10, and the condenser 8 is arranged beside the compressor 9; the heat exchange box 2 comprises: a flow tube 3, a cold trap 4, a temperature sensor 5, a heat insulation layer 6, a solenoid valve interface 7 and a cold trap connection end 11; the flow tube 3 is arranged on the outer wall of the lower section of the cold trap 4; the outer wall of the upper section of the cold trap 4 is provided with a heat insulation layer 6; the solenoid valve interface 7 is arranged at the upper end inside the heat exchange box 2, and the temperature sensor 5 is arranged on the cold trap 4; one end of the cold trap 4 is connected to the cold trap connection end 11.

[0006] As mentioned above, the heat exchange box 2 also includes two cylindrical cold trap studios, the inner diameter of the cold trap studio is slightly larger than the outer diameter of the cold trap 4; there are two cold traps 4, one cold trap 4 is placed in each cold trap studio, and a refrigeration coil is welded on the outer wall of the cold trap studio; two platinum resistance thermometers are arranged in the cold trap studio, and the cold trap studio is made of high-temperature hard polyurethane foam insulation material as a whole.

[0007] As mentioned above, there is a small amount of special synthetic heat transfer oil at the bottom of the cold trap 4; each cold trap studio is divided into a deep cold zone, an insulation zone and a heating zone from the bottom to the top, and a polytetrafluoroethylene plate is used in the insulation zone. The size of the polytetrafluoroethylene plate is the same as the size of the metal cylinder at the bottom of the cold trap studio. The polytetrafluoroethylene plate is fixed to the deep cold zone at the bottom of the cold trap studio through a slot; the upper heating zone of the cold trap studio adopts a nickel-chromium alloy stainless steel fin tube heater for heating, and is connected with the polytetrafluoroethylene cylinder in the middle insulation zone of the cold trap studio through a slot to prevent water vapor in the air from condensing on the surface.

[0008] As mentioned above, a cold trap flange is also provided on the cold trap 4, and a heating belt is wound on the upper end of the cold trap flange. The heating belt is powered by an 80V power module, and the power module is controlled by a relay; the heat exchange box 2 is also provided with two operating modes: manual defrosting and automatic defrosting. During automatic operation, as the compressor 9 starts cooling, the heating device is started to heat the top. Through the heating voltage control in the heat exchange box 2, the low heating power output of the high-power heater is effectively controlled to achieve a certain control effect.

[0009] As mentioned above, the heat exchange box 2 is also provided with an interlocking protection device, which is connected to the temperature sensor 5. When the temperature in the cryogenic device exceeds the set value, the interlocking protection device self-locks and cuts off the passage between the cold trap and the mass spectrometer injection system; a high vacuum electromagnetic flapper valve is used in the interlocking protection device, and the electromagnetic flapper valve has a working range of 10 5 ~1.0×10 -5 Pa, the internal and external interfaces of the interlocking protection device are consistent with the inlet and outlet sizes of the cold trap, and the opening and closing time of the interlocking protection device is less than 3S.

[0010] As mentioned above, the refrigerator 1 also includes: an energy regulator and a pressure testing system; the refrigerator 1 distributes the refrigeration capacity through the proportion of the mixed refrigerant acting in different temperature sections, adjusts the pressure conditions in the device through three or four solenoid valves, and recovers part of the refrigerant to the energy regulator in the refrigerator 1 in the high temperature section and constant temperature, thereby reducing the cooling output and multiples of the power consumption. The energy regulator and the pressure testing system in the refrigerator 1 cooperate with each other to achieve the highest efficiency operation.

[0011] As mentioned above, the water supply temperature in the condenser 8 is less than 25°C and the water flow rate is less than 2m 3 / h, the flow pipe diameter in the condenser 8 is not less than 20mm.

[0012] The refrigeration method of a mass spectrometer cryogenic device as described above comprises the following steps:

[0013] Step 1: Move the cryogenic device to the cold trap side of the mass spectrometer sampling system, and fit the heat exchange box 2 with the cold trap installation platform; remove the cold trap 4 of the mass spectrometer from the fixed workbench, close all hand valves, and disconnect the connected pipes; put the cold trap 4 into the cold trap studio in the heat exchange box 2, and use a vernier caliper to measure the gap width between the cold trap in the cylindrical tube and the wall surface.; Take out the cold trap 4 and evenly wrap aluminum foil on the cold trap wall surface according to the gap width to increase the outer diameter; add an appropriate amount of synthetic heat transfer oil to the bottom of the cold trap 4, put in a temperature detection probe, and put the cold trap 4 in the cold trap studio; the second cold trap 4 is also installed according to the above method.

[0014] Step 2: Connect the power supply of the cryogenic device and check the electrical insulation; use a metal hose to connect the circulating water interface on the cryogenic device with the preset cooling water interface in the laboratory, open the valve at the interface to allow the circulating water to circulate, and check that there is no leakage in the interface; install the solenoid valve drive device in the interlocking protection device to the solenoid valve interface 7 at the upper end of the heat exchange box 2, install solenoid valves at the outlet and inlet of the cold trap respectively and connect wires; use a bellows to connect to the injection system of the mass spectrometer at the solenoid valve interface 7 without changing the original vacuum line; Step 3: Start the cryogenic device, set the temperature value of the interlocking protection device, and perform an interlocking protection function test; after it is normal, set the temperature setting value of the cryogenic device below the design value, make the cryogenic device run at the limit, and detect temperature changes; when the temperature of the cold trap 4 reaches the limit value, open the cold trap manual valve and observe the vacuum changes in the injection system; after the vacuum reaches the set requirements, perform mass spectrometer sampling time, memory effect, and double standard measurement checks, and carry out production operation after passing the test.

[0015] The present invention has the following beneficial effects:

[0016] A mass spectrometer cryogenic device designed by the present invention meets the working requirements of the mass spectrometer cold trap, and uses a one-piece mainframe structure with single-stage compression to reduce refrigeration loss; the internal heat exchange box of the present invention effectively prevents the wall surface of the upper end of the mass spectrometer cold trap from icing; by modifying and installing a circulating cooling water pipeline, water cooling and heat dissipation are achieved, ensuring the control of laboratory environment temperature and humidity; the electromagnetic valve interlocking protection device designed for device safety enables the cryogenic device to be safely used in unattended conditions. The developed cryogenic device can operate continuously at -175℃ in application, which is better than the design index. The sampling time of the mass spectrometer is less than 30S, the memory effect of the injection system is less than 1.003, and the relative standard deviation and system relative deviation of the mass spectrometer measurement are both less than 0.04%, with good application effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a mass spectrometer cryogenic device designed by the present invention;

[0018] Figure 2It is a schematic diagram of the connection mode of the flow pipe in the deep cooling device of a mass spectrometer designed by the present invention;

[0019] Figure 3 It is a schematic diagram of the structure of a heat exchange box of a mass spectrometer cryogenic device designed by the present invention;

[0020] Figure 4 It is a cooling method of a cold trap in a mass spectrometer cryogenic device designed by the present invention;

[0021] Figure 5 The figure is a side view of a deep cooling device of a mass spectrometer designed by the present invention.

[0022] Among them, 1. Refrigeration host; 2. Heat exchange box; 3. Flow pipe, 4-cold trap, 5-temperature sensor, 6-insulation layer, 7-solenoid valve interface, 8-condenser, 9-compressor, 10-mixed working fluid storage tank, 11-cold trap connection end; DETAILED DESCRIPTION

[0023] A mass spectrometer cryogenic device of the present invention is further described below:

[0024] like Figures 1 to 5 As shown, a mass spectrometer cryogenic device comprises: a refrigeration main unit 1 and a heat exchange box 2, wherein the refrigeration main unit 1 and the heat exchange box 2 are integrally connected; the refrigeration main unit 1 comprises: a condenser 8, a compressor 9 and a mixed working fluid storage tank 10; the compressor 9 is provided with a mixed working fluid storage tank 10, and the condenser 8 is arranged next to the compressor 9; the heat exchange box 2 comprises: a flow tube 3, a cold trap 4, a temperature sensor 5, a heat insulation layer 6, a solenoid valve interface 7 and a cold trap connection end 11; the flow tube 3 is arranged on the outer wall of the lower section of the cold trap 4; the outer wall of the upper section of the cold trap 4 is provided with a heat insulation layer 6; the solenoid valve interface 7 is arranged at the upper end inside the heat exchange box 2, and the temperature sensor 5 is arranged on the cold trap 4; one end of the cold trap 4 is connected to the cold trap connection end 11.

[0025] As mentioned above, the heat exchange box 2 also includes two cylindrical cold trap studios, the inner diameter of the cold trap studio is slightly larger than the outer diameter of the cold trap 4; there are two cold traps 4, one cold trap 4 is placed in each cold trap studio, and a refrigeration coil is welded on the outer wall of the cold trap studio; two platinum resistance thermometers are arranged in the cold trap studio, and the cold trap studio is made of high-temperature hard polyurethane foam insulation material as a whole.

[0026] The inner wall of the cold trap working chamber is made of stainless steel and fully welded, and the outer shell is made of high-quality cold-rolled steel plate, and the surface is electrostatically sprayed after pickling and phosphating.

[0027] The heat exchange box 2 is adjacent to the mass spectrometer sampling system, and the flow pipe 3 is connected to the refrigeration unit to continuously keep the heat exchange chamber at a set low temperature state through wall heat transfer.

[0028] As mentioned above, there is a small amount of special synthetic heat transfer oil at the bottom of the cold trap 4; each cold trap studio is divided into a deep cold zone, an insulation zone and a heating zone from the bottom to the top in sequence to prevent ice and frost problems in later operation; a polytetrafluoroethylene plate is used in the insulation zone, and the size of the polytetrafluoroethylene plate is the same as the size of the metal cylinder at the bottom of the cold trap studio, and the polytetrafluoroethylene plate is fixed to the deep cold zone at the bottom of the cold trap studio through a slot; a nickel-chromium alloy stainless steel finned tube heater is used for heating in the upper heating zone of the cold trap studio, and is connected to the polytetrafluoroethylene cylinder in the insulation zone in the middle of the cold trap studio through a slot to prevent water vapor in the air from condensing on the surface.

[0029] As mentioned above, a cold trap flange is also provided on the cold trap 4, and a heating belt is wound on the upper end of the cold trap flange. The heating belt is powered by an 80V power module, and the power module is controlled by a relay; the heat exchange box 2 is also provided with two operating modes: manual defrosting and automatic defrosting. During automatic operation, as the compressor 9 starts refrigeration, the heating device is started to heat the top, and the heating voltage control in the heat exchange box 2 has a better adjustment effect on the constant temperature and low temperature section slope; the forced balanced temperature control is optimized through the control strategy to avoid a long stabilization process, effectively control the low heating power output of the high-power heater, and achieve a stable control effect.

[0030] As mentioned above, the heat exchange box 2 is also provided with an interlocking protection device, which is connected to the temperature sensor 5. When the temperature in the cryogenic device exceeds the set value, the interlocking protection device self-locks and cuts off the passage between the cold trap and the mass spectrometer injection system; a high vacuum electromagnetic flapper valve is used in the interlocking protection device, and the electromagnetic flapper valve has a working range of 10 5 ~1.0×10 -5 Pa, the internal and external interfaces of the interlocking protection device are consistent with the inlet and outlet sizes of the cold trap, and the opening and closing time of the interlocking protection device is less than 3S.

[0031] As mentioned above, the refrigerator 1 also includes: an energy regulator and a pressure testing system; the refrigerator 1 distributes the refrigeration capacity through the proportion of the mixed refrigerant acting in different temperature sections, and adjusts the pressure conditions in the device through three or four solenoid valves, so as to achieve constant cooling output in a specific temperature section. The cooling capacity distribution of the entire cooling process is more uniform, the temperature curve is smoother, and part of the refrigerant is recovered to the energy regulator in the refrigerator 1 in the high temperature section and constant temperature, thereby reducing the cooling output and reducing the power consumption by multiples. The energy regulator and the pressure testing system in the refrigerator 1 work together to achieve the highest efficiency operation.

[0032] In order to ensure the continuous safe and stable operation of the unit, water cooling is used in the refrigerator to dissipate heat. As mentioned above, the water supply temperature in the condenser 8 is less than 25°C and the water flow rate is less than 2m 3 / h, the flow pipe diameter in the condenser 8 is not less than 20mm.

[0033] The refrigeration method of a mass spectrometer cryogenic device as described above comprises the following steps:

[0034] Step 1: Move the cryogenic device to the cold trap side of the mass spectrometer injection system, and fit the heat exchange box 2 with the cold trap installation platform; remove the cold trap 4 of the mass spectrometer from the fixed workbench, close all hand valves, and disconnect the connected pipes; place the cold trap 4 in the cold trap studio in the heat exchange box 2, and use a vernier caliper to measure the gap width between the cold trap in the cylinder and the wall. Take out the cold trap 4 and evenly wrap aluminum foil on the wall of the cold trap according to the gap width to increase the outer diameter; add an appropriate amount of synthetic heat transfer oil to the bottom of the cold trap 4, put in a temperature detection probe, and put the cold trap 4 in the cold trap studio; the second cold trap 4 is also installed according to the above method.

[0035] Step 2: Connect the power supply of the cryogenic device and check the electrical insulation; use a metal hose to connect the circulating water interface on the cryogenic device with the preset cooling water interface in the laboratory, open the valve at the interface to allow the circulating water to circulate, and check that there is no leakage in the interface; install the solenoid valve drive device in the interlocking protection device to the solenoid valve interface 7 at the upper end of the heat exchange box 2, install solenoid valves at the outlet and inlet of the cold trap respectively and connect wires; use a bellows to connect to the injection system of the mass spectrometer at the solenoid valve interface 7 without changing the original vacuum line; Step 3: Start the cryogenic device, set the temperature value of the interlocking protection device, and perform an interlocking protection function test; after it is normal, set the temperature setting value of the cryogenic device below the design value, make the cryogenic device run at the limit, and detect temperature changes; when the temperature of the cold trap 4 reaches the limit value, open the cold trap manual valve and observe the vacuum changes in the injection system; after the vacuum reaches the set requirements, perform mass spectrometer sampling time, memory effect, and double standard measurement checks, and carry out production operation after passing the test.

[0036] The present invention is described in detail above in conjunction with the embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A mass spectrometer cryogenic device, characterized in that: include: A refrigeration main unit (1) and a heat exchange box (2), wherein the refrigeration main unit (1) and the heat exchange box (2) are integrally connected; The refrigeration main unit (1) comprises: a condenser (8), a compressor (9) and a mixed working fluid storage tank (10); the compressor (9) is provided with a mixed working fluid storage tank (10), and the condenser (8) is arranged beside the compressor (9); the heat exchange box (2) comprises: a flow pipe (3), a cold trap (4), a temperature sensor (5), a heat insulation layer (6), a solenoid valve interface (7) and a cold trap connection end (11); the flow pipe (3) is arranged on the outer wall of the lower section of the cold trap (4); the outer wall of the upper section of the cold trap (4) is provided with a heat insulation layer (6); the solenoid valve interface (7) is arranged at the upper end of the heat exchange box (2), and the temperature sensor (5) is arranged on the cold trap (4); one end of the cold trap (4) is connected to the cold trap connection end (11); The heat exchange box (2) further comprises two cylindrical cold trap working chambers, the inner diameter of the cold trap working chambers being slightly larger than the outer diameter of the cold trap (4); the number of the cold traps (4) is two, one cold trap (4) is placed in each cold trap working chamber, and a refrigeration coil is welded to the outer wall of the cold trap working chamber; two platinum resistance thermometers are arranged in the cold trap working chamber, and the cold trap working chamber is made of high-temperature hard polyurethane foam insulation material as a whole.

2. A mass spectrometer cryogenic device as claimed in claim 1, characterized in that: A small amount of synthetic heat transfer oil is provided at the bottom of the cold trap (4); each cold trap working room is divided into a deep cooling zone, a heat insulation zone and a heating zone from the bottom to the top, a polytetrafluoroethylene plate is used in the heat insulation zone, the size of the polytetrafluoroethylene plate is the same as the size of the metal cylinder at the bottom of the cold trap working room, and the polytetrafluoroethylene plate is fixed to the deep cooling zone at the bottom of the cold trap working room through a slot; a nickel-chromium alloy stainless steel finned tube heater is used for heating in the upper heating zone of the cold trap working room, and is connected to the polytetrafluoroethylene cylinder in the heat insulation zone in the middle of the cold trap working room through a slot to prevent water vapor in the air from condensing on the surface.

3. A mass spectrometer cryogenic device as claimed in claim 2, characterized in that: The cold trap (4) is also provided with a cold trap flange, and a heating belt is wound around the upper end of the cold trap flange. The heating belt is powered by an 80V power module, and the power module is controlled by a relay. The heat exchange box (2) is also provided with two operating modes: manual defrosting and automatic defrosting. During automatic operation, as the compressor (9) starts cooling, the heating device is started to heat the top. By controlling the heating voltage in the heat exchange box (2), the low heating power output of the high-power heater is effectively controlled, thereby achieving a stable control effect.

4. A mass spectrometer cryogenic device as claimed in claim 3, characterized in that: The heat exchange box (2) is also provided with an interlocking protection device, which is connected to the temperature sensor (5). When the temperature in the cryogenic device exceeds a set value, the interlocking protection device self-locks and cuts off the passage between the cold trap and the mass spectrometer injection system. A high vacuum electromagnetic flapper valve is used in the interlocking protection device, and the electromagnetic flapper valve has a working range of 10 5 ~1.0×10 -5 Pa, the internal and external interfaces of the interlocking protection device are consistent with the inlet and outlet sizes of the cold trap, and the opening and closing time of the interlocking protection device is less than 3s.

5. A mass spectrometer cryogenic device as claimed in claim 4, characterized in that: The refrigeration main unit (1) further comprises: an energy regulator and a pressure testing system; the refrigeration main unit (1) distributes the refrigeration capacity by the proportion of the mixed refrigerant acting in different temperature ranges, adjusts the pressure condition in the device through three or four solenoid valves, and recovers part of the refrigerant to the energy regulator in the refrigeration main unit (1) in the high temperature range and constant temperature, thereby reducing the output of cooling capacity and reducing power consumption by multiples. The energy regulator and the pressure testing system in the refrigeration main unit (1) cooperate to achieve the highest efficiency operation.

6. A mass spectrometer cryogenic device as claimed in claim 5, characterized in that: The water supply temperature in the condenser (8) is less than 25°C and the water flow rate is less than 2m 3 / h, the flow pipe diameter in the condenser (8) is not less than 20mm.

7. A refrigeration method for a mass spectrometer cryogenic device according to any one of claims 1 to 6, characterized in that The steps include: Step 1: Move the cryogenic device to the cold trap side of the mass spectrometer sampling system, and fit the heat exchange box (2) to the cold trap mounting platform; remove the cold trap (4) of the mass spectrometer from the fixed workbench, close all hand valves, and disconnect the connected pipes; place the cold trap (4) in the cold trap working room inside the heat exchange box (2), and use a vernier caliper to measure the gap width between the cold trap in the cylindrical tube and the wall surface; take out the cold trap (4) and evenly wrap aluminum foil on the wall surface of the cold trap according to the gap width to increase the outer diameter; add an appropriate amount of synthetic heat transfer oil to the bottom of the cold trap (4), put in a temperature detection probe, and put the cold trap (4) in the cold trap working room; the second cold trap (4) is installed in the same manner as above; Step 2: Connect the power supply of the cryogenic device and check the electrical insulation; use a metal hose to connect the circulating water interface on the cryogenic device to the preset cooling water interface in the laboratory, open the valve at the interface to allow the circulating water to circulate, and check that there is no leakage in the interface; install the solenoid valve drive device in the interlocking protection device to the solenoid valve interface (7) at the upper end of the heat exchange box (2), install solenoid valves at the outlet and inlet of the cold trap respectively and connect the wires; use a bellows to connect the mass spectrometer sampling system at the solenoid valve interface (7) without changing the original vacuum line; Step 3: Start the cryogenic device, set the temperature value of the interlocking protection device, and perform the interlocking protection function test; after it is normal, set the temperature value of the cryogenic device below the design value, make the cryogenic device run at the limit, and detect the temperature change; when the temperature of the cold trap (4) reaches the limit value, open the cold trap manual valve and observe the vacuum change in the sampling system; after the vacuum reaches the set requirements, perform the mass spectrometer sampling time, memory effect, and double standard measurement inspection, and carry out production operation after passing the inspection.

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