A production device and production process for producing ultrapure oxygen and liquid nitrogen using a precooling system

Abstract

The present invention relates to a production device and a production process for producing ultrapure oxygen and liquid nitrogen by using a precooling system; the device comprises an ultrapure oxygen production system and a liquid nitrogen preparation system, wherein the ultrapure oxygen production system comprises an oxygen raw material storage tank, and the oxygen raw material storage tank is connected to the ultrapure oxygen storage tank through a raw material heat exchange unit and a thermally coupled distillation tower; the liquid nitrogen preparation system and the cold supply system respectively provide cold capacity for the raw material heat exchange unit; the liquid nitrogen preparation system respectively provides cold capacity for the thermally coupled distillation tower and the top condenser at the top of the thermally coupled distillation tower; the device has the advantages of simple structure, reasonable process design, upper and lower towers and a circulating refrigeration process, small device footprint, low investment, stable products, and the ability to produce liquid nitrogen as a by-product while obtaining ultrapure oxygen products.

Description

Technical Field

[0001] The invention belongs to the technical field of coupled production of ultrapure liquid oxygen and liquefied nitrogen, and in particular relates to a production device and a production process for producing ultrapure oxygen and liquid nitrogen by using a precooling system. Background Art

[0002] Ultrapure oxygen has great application prospects in the fields of semiconductor components, integrated circuits, photovoltaic industry, etc., but it is very difficult to prepare ultrapure oxygen in industry. As we all know, air is an inexhaustible source of industrial oxygen production. There are four methods for air separation and oxygen production, namely, low-temperature distillation, normal temperature pressure swing adsorption, membrane separation and high temperature alkaline molten salt catalytic absorption. Since air is mainly composed of nitrogen, oxygen, argon, carbon dioxide, methane, oxygen, etc., the industrial oxygen produced by air separation is complex, especially containing impurities such as argon and nitrogen that are difficult to remove by normal temperature separation. It is very difficult to prepare ultrapure oxygen using such industrial oxygen as raw material. Based on this, low-temperature distillation is mainly used in industry to produce ultrapure oxygen, but in the process of producing ultrapure oxygen, oxygen needs to be liquefied and in a low-temperature state to achieve the purpose of distillation and purification, which invisibly consumes a lot of cold capacity, which not only causes waste of cold capacity, but also has defects such as oxygen venting. Summary of the invention

[0003] The object of the present invention is to overcome the defects in the prior art and to provide a production device and a production process for producing ultra-pure oxygen and liquid nitrogen by using a precooling system, which has a simple structure, a reasonable process design, adopts upper and lower towers and a circulating refrigeration process, has a small device footprint, requires little investment, produces stable products, and can produce liquid nitrogen as a by-product while obtaining ultra-pure oxygen products.

[0004] The object of the present invention is achieved in that:

[0005] A production device for producing ultrapure oxygen and liquid nitrogen using a precooling system, the production device comprising an ultrapure oxygen production system,

[0006] The ultrapure oxygen production system comprises an oxygen raw material storage tank, which is connected to the ultrapure oxygen storage tank via a raw material heat exchange unit and a thermally coupled distillation tower;

[0007] The liquid nitrogen preparation system and the cold supply system provide cold capacity for the raw material heat exchange unit respectively;

[0008] The liquid nitrogen preparation system provides cooling capacity for the thermally coupled distillation tower and the top condenser at the top of the thermally coupled distillation tower.

[0009] Preferably, the thermally coupled distillation tower comprises a lower distillation tower and an upper distillation tower arranged on the top of the lower distillation tower;

[0010] The outlet of the raw material heat exchange unit is connected to the first raw material liquid inlet of the lower distillation tower in the lower distillation tower, the gas phase outlet at the top of the lower distillation tower is connected to the upper tower reboiler and the first raw material gas inlet of the upper distillation tower of the upper distillation tower through the second tee, and the liquid phase outlet of the upper distillation tower at the bottom of the upper distillation tower is connected to the ultra-pure oxygen storage tank.

[0011] Preferably, a fifth regulating valve is provided between the second tee and the upper tower reboiler, and a sixth regulating valve is provided between the second tee and the upper tower distillation tower feed gas inlet of the upper tower distillation tower.

[0012] Preferably, the liquid phase outlet at the bottom of the lower distillation tower is connected to the liquid oxygen atmospheric pressure storage tank through a ninth regulating valve;

[0013] The outlet of the upper tower reboiler is connected to the second raw liquid inlet of the lower tower distillation tower at the upper part of the lower tower distillation tower;

[0014] The gas phase outlet at the top of the upper distillation tower is connected to the upper distillation tower raw liquid inlet of the upper distillation tower through the pipe side of the top condenser and the tenth regulating valve;

[0015] A seventh regulating valve is provided between the liquid phase outlet at the bottom of the upper distillation tower and the ultrapure oxygen storage tank, and the outlet of the ultrapure oxygen storage tank is connected to the filling row through a filling pump;

[0016] A third tee is provided between the tube side of the top condenser and the tenth regulating valve, a fourth tee is provided between the outlet of the upper tower reboiler and the inlet of the second raw liquid of the lower tower distillation tower, and a shortcut pipeline is provided between the third end of the third tee and the third end of the fourth tee.

[0017] Preferably, the raw material heat exchange unit includes a precooler and a main heat exchanger, and the oxygen raw material storage tank is connected to the first raw material liquid inlet of the lower distillation tower through the first raw material gas inlet of the precooler, the first raw material gas outlet of the precooler, the first raw material gas inlet of the main heat exchanger, the first raw material gas outlet of the main heat exchanger and the eighth regulating valve.

[0018] Preferably, the liquid nitrogen preparation system includes a nitrogen compressor, and the outlet of the nitrogen compressor is connected to the second raw gas inlet of the precooler, the second raw gas outlet of the precooler, the second raw gas inlet of the main heat exchanger, the second raw gas outlet of the main heat exchanger, the second regulating valve and the liquid nitrogen atmospheric pressure storage tank through a four-way valve.

[0019] Preferably, the third end of the four-way is connected to the inlet of the nitrogen compressor through the first regulating valve, the lower tower reboiler, the fourth regulating valve, the shell side of the top condenser, the third raw gas inlet of the precooler, the third raw gas outlet of the precooler and the first three-way in sequence, and an air intake pipeline with a nitrogen raw material storage tank is provided between the first three-way and the inlet of the nitrogen compressor.

[0020] Preferably, the fourth end of the four-way is connected to the third end of the first three-way through the nitrogen expansion compressor, the main heat exchanger raw material inlet and the main heat exchanger raw material outlet of the main heat exchanger in sequence.

[0021] Preferably, the cold supply system comprises an R23 refrigerant tank, the outlet of the R23 refrigerant tank is connected to the inlet of the R23 refrigerant tank via a third regulating valve, a precooler raw material inlet of the precooler, a precooler raw material outlet and an R23 compressor.

[0022] A production process for a production device for producing ultrapure oxygen and liquid nitrogen using a precooling system, the production process comprising the following steps:

[0023] Step 1: The raw oxygen in the oxygen raw material storage tank is precooled by the precooler, enters the main heat exchanger to continue cooling, and enters the lower tower distillation tower through the first raw liquid inlet in the lower tower distillation tower; the temperature of the raw oxygen is: 20-30°C, the pressure is: 0.5Mpa, the flow rate is: 5000Nm / h, the gas phase fraction is: 1, and the oxygen molar fraction is: 99.5-99.6%;

[0024] Step 2: subjecting the raw material liquid entering the lower distillation tower in step 1 to a distillation purification, and the gas phase after distillation purification enters the upper tower reboiler and the upper distillation tower respectively through the second three-way; the gas phase outlet temperature of the top of the lower distillation tower 4 is: -175~-177℃, and the oxygen mole fraction is: 99.9~99.95%;

[0025] Step 3: The gas phase in step 2 enters the upper distillation tower and then undergoes secondary distillation. The liquid phase after the secondary distillation enters the ultrapure oxygen storage tank through the liquid phase outlet of the upper distillation tower, and then enters the filling row through the filling pump; the liquid phase temperature after the secondary distillation is: -181 to 183°C, and the molar purity of the ultrapure oxygen is not less than 99.9999%;

[0026] Step 4: the liquid phase after the primary distillation in the lower distillation tower in step 2 enters the liquid oxygen atmospheric pressure storage tank through the liquid phase outlet at the bottom of the lower distillation tower and the ninth regulating valve for industrial oxygen recovery;

[0027] Step 5: The gas phase after the secondary rectification in step 3 is liquefied through the tube heat exchange of the top condenser and then enters the third tee, and a part of it enters the upper distillation tower through the tenth regulating valve and the raw liquid inlet of the upper distillation tower for reflux; the temperature at the raw liquid inlet of the upper distillation tower is -181.5 to -183.5°C; the other part enters the fourth tee through the shortcut pipeline; the material passing through the upper tower reboiler in step 2 enters the fourth tee; the above two are merged in the fourth tee and refluxed to the lower distillation tower through the second raw liquid inlet of the lower distillation tower;

[0028] Step 6: The refrigerant R23 in the R23 refrigerant tank is throttled through the third regulating valve, and after throttling, it is reheated through the precooler raw material inlet and the precooler raw material outlet of the precooler, and after reheating, it enters the R23 refrigerant tank through the R23 compressor and the inlet of the R23 refrigerant tank; the temperature at the inlet of the R23 compressor is: -48 to -50 ° C, and the mole fraction of R23 is: 100%;

[0029] Step 7: The compressed nitrogen at the outlet of the nitrogen compressor enters the liquid nitrogen atmospheric pressure storage tank through a four-way valve in sequence with the second raw gas inlet of the precooler, the second raw gas outlet of the precooler, the second raw gas inlet of the main heat exchanger, the second raw gas outlet of the main heat exchanger, and the second regulating valve; the temperature of the second raw gas outlet of the main heat exchanger is: -182~-184℃, and the pressure is: 0.01~0.03mPaG;

[0030] Step 8: The compressed nitrogen in the third end of the four-way in step 7 enters the lower tower reboiler through the first regulating valve and exchanges heat with the lower tower distillation tower. After the heat exchange, it is throttled by the fourth regulating valve to the top condenser to provide cooling capacity, and heat is exchanged again with the gas phase from the upper tower distillation tower in the top condenser. After the heat exchange again, it passes through the shell side of the top condenser, the third raw gas inlet of the precooler, the third raw gas outlet of the precooler and the first three-way to enter the nitrogen compressor to form a cycle; the temperature of the third raw gas inlet of the precooler is: -184~-187℃, and the flow rate is: 4000~4200Nm 3 / h, gas phase fraction: 1; the outlet temperature of the third raw gas of the precooler is 30-35°C, and the pressure is: 1.3-1.5mPaG;

[0031] Step 9: The compressed nitrogen in the fourth end of the four-way in step 7 enters the main heat exchanger through the nitrogen expander to provide cooling capacity, and enters the nitrogen compressor for cyclic compression through the main heat exchanger raw material outlet of the main heat exchanger and the third end of the first three-way; the expander outlet pipeline temperature is: -183 ~ -185 ° C, pressure: 0.02 ~ 0.03mPaG;

[0032] Step 10: The raw nitrogen in the nitrogen raw material storage tank is added to the liquid nitrogen preparation system through the air inlet pipeline; the specifications of the raw nitrogen are: 0.4MPaG / 25℃, 3500Nm 3 / h.

[0033] According to the above scheme, a production device and a production process for producing ultra-pure oxygen and liquid nitrogen using a pre-cooling system are manufactured. An industrial-grade low-pressure oxygen is used to provide the raw material for ultra-pure oxygen, and the working principle of R23 working fluid refrigeration and expansion mechanism refrigeration is utilized. The upper and lower towers are coupled with distillation to stably produce an ultra-pure oxygen purification process and a device for rich liquid nitrogen with a product purity of not less than 99.9999%. Compared with the traditional process technology, the present invention has the following advantages: 1. The raw oxygen and nitrogen are cooled for the first time by using R23 working medium refrigeration, and the liquefaction of oxygen and nitrogen is realized after heat exchange by the expansion machine, which saves energy consumption and is beneficial to environmental protection; 2. The ultra-pure oxygen device adopts the upper and lower tower coupling distillation technology to obtain ultra-pure oxygen products, which are stored in ultra-pure oxygen storage tanks and then used to fill bottled gas through liquid pumps. Liquid ultra-pure oxygen products and gas ultra-pure oxygen products can be sold at the same time to meet the sales needs of tank trucks and bottled gas; 3. The product purity can reach more than 99.9999%, which solves the dependence of the domestic semiconductor industry on imported ultra-pure oxygen and provides sufficient research for the domestic semiconductor industry and electronic special gas industry. Raw materials, promoting the development of economic and social benefits; 4. The energy of the present invention is highly integrated. Specifically, the top gas of the lower tower provides a heat source for the reboiler of the upper tower, reducing the load of the nitrogen compressor and reducing the energy consumption of the device; 5. The present invention also includes the design of a pre-cooling system, which can greatly reduce the circulation volume of the nitrogen compressor, thereby reducing the energy consumption per unit product, and is beneficial to the balance of the system load and convenient operation; 6. At the same time, the present invention can achieve the process of recycling and reusing working fluids and oxygen and nitrogen without venting, maximizing the utilization of the device's cold capacity, and the produced liquid ultra-pure oxygen is used in semiconductor components and integrated circuits, photovoltaic industry and other fields, and liquid nitrogen is used for consumption in other devices or sold externally, thereby achieving the characteristics of saving investment and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of the present invention.

[0035] Figure 2 It is a schematic diagram of the structure of the thermally coupled distillation tower of the present invention.

[0036] In the above picture:

[0037] 1. Oxygen raw material storage tank; 2. Precooler; 3. Main heat exchanger; 4. Lower tower distillation tower; 5. Upper tower distillation tower; 6. Top condenser; 7. Lower tower reboiler; 8. Upper tower reboiler; 9. Ultrapure oxygen storage tank; 10. Filling pump; 11. Filling row; 12. R23 compressor; 13. R23 refrigerant tank; 14. Nitrogen compressor; 15. Nitrogen expander; 16. Liquid oxygen atmospheric pressure storage tank; 17. Liquid nitrogen atmospheric pressure storage tank; 18. Fifth regulating valve; 19. Sixth regulating valve; 20. Tenth regulating valve; 21. Seventh regulating valve; 22. First regulating valve; 23. Fourth regulating valve; 24. Third regulating valve; 25. Second regulating valve; 26. Ninth regulating valve; 27. First raw material liquid inlet of lower tower distillation tower; 28. First raw material gas inlet of precooler; 29. ​​Raw material liquid inlet of upper tower distillation tower; 30 , the second raw material gas outlet of the precooler; 31, the liquid phase outlet of the upper tower distillation tower; 32, the second raw material liquid inlet of the lower tower distillation tower; 33, the second raw material gas outlet of the main heat exchanger; 34, the raw material gas inlet of the upper tower distillation tower; 35, the raw material inlet of the precooler; 36, the third raw material gas inlet of the precooler 36; 37, the first three-way; 38, the four-way; 39, the raw material inlet of the main heat exchanger; 40, the second raw material gas inlet of the precooler; 41, the second raw material gas inlet of the main heat exchanger; 42, the first raw material gas outlet of the precooler; 43, the first raw material gas inlet of the main heat exchanger; 44, the first raw material gas outlet of the main heat exchanger; 45, the nitrogen raw material storage tank; 46, the eighth regulating valve; 47, the second three-way; 48, the raw material outlet of the precooler; 49, the raw material outlet of the main heat exchanger; 50, the third three-way; 51, the fourth three-way; 52, the shortcut pipeline. DETAILED DESCRIPTION

[0038] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation of the present invention is now described with reference to the accompanying drawings, in which the same reference numerals represent the same components. In order to make the drawings concise, each figure only schematically shows the parts related to the invention, and they do not represent the actual structure of the product.

[0039] like Figure 1 , 2 As shown, the present invention is a production device and a production process for producing ultrapure oxygen and liquid nitrogen using a precooling system, wherein the production device includes an ultrapure oxygen production system, and the ultrapure oxygen production system includes an oxygen raw material storage tank 1, and the oxygen raw material storage tank 1 is connected to the ultrapure oxygen storage tank 9 through a raw material heat exchange unit and a thermally coupled distillation tower; the liquid nitrogen preparation system and the cold supply system respectively provide cold energy for the raw material heat exchange unit; the liquid nitrogen preparation system respectively provides cold energy for the thermally coupled distillation tower and the top condenser 6 at the top of the thermally coupled distillation tower.

[0040] Furthermore, the thermally coupled distillation tower includes a lower distillation tower 4 and an upper distillation tower 5 arranged on the top of the lower distillation tower 4; the outlet of the raw material heat exchange unit is connected to the first raw liquid inlet 27 of the lower distillation tower in the lower distillation tower 4, and the gas phase outlet at the top of the lower distillation tower 4 is connected to the upper tower reboiler 8 and the first raw gas inlet 34 of the upper distillation tower 5 through the second three-way 47, and the bottom 31 of the upper distillation tower 5 is connected to the ultra-pure oxygen storage tank 9.

[0041] Furthermore, a fifth regulating valve 18 is provided between the second three-way valve 47 and the upper tower reboiler 8 , and a sixth regulating valve 19 is provided between the second three-way valve 47 and the upper tower distillation tower feed gas inlet 34 of the upper tower distillation tower 5 .

[0042] Further, the liquid phase outlet at the bottom of the lower tower distillation tower 4 is connected to the liquid oxygen atmospheric pressure storage tank 16 through the ninth regulating valve 26; the outlet of the upper tower reboiler 8 is connected to the second raw liquid inlet 32 ​​of the lower tower distillation tower at the upper part of the lower tower distillation tower 4; the gas phase outlet at the top of the upper tower distillation tower 5 is connected to the upper tower distillation tower raw liquid inlet 29 of the upper tower distillation tower 5 through the pipe side of the top condenser 6 and the tenth regulating valve 20; a seventh regulating valve 21 is provided between the liquid phase outlet at the bottom of the upper tower distillation tower 5 and the ultra-pure oxygen storage tank 9, and the outlet of the ultra-pure oxygen storage tank 9 is connected to the filling row 11 through the filling pump 10; a third three-way 50 is provided between the pipe side of the top condenser 6 and the tenth regulating valve 20, a fourth three-way 51 is provided between the outlet of the upper tower reboiler 8 and the second raw liquid inlet 32 ​​of the lower tower distillation tower, and a shortcut pipeline 52 is provided between the third end of the third three-way 50 and the third end of the fourth three-way 51.

[0043] Furthermore, the raw material heat exchange unit includes a precooler 2 and a main heat exchanger 3, and the oxygen raw material storage tank 1 is connected to the first raw material liquid inlet 27 of the lower distillation tower through the precooler first raw material gas inlet 28 of the precooler 2, the first raw material gas outlet 42 of the precooler, the main heat exchanger first raw material gas inlet 43 of the main heat exchanger 3, the main heat exchanger first raw material gas outlet 44 and the eighth regulating valve 46.

[0044] Furthermore, the liquid nitrogen preparation system includes a nitrogen compressor 14, and the outlet of the nitrogen compressor 14 is connected to the precooler second raw gas inlet 40 of the precooler 2, the precooler second raw gas outlet 30, the main heat exchanger second raw gas inlet 41 of the main heat exchanger 3, the main heat exchanger second raw gas outlet 33 and the second regulating valve 25 and the liquid nitrogen atmospheric pressure storage tank 17 through a four-way 38 in sequence.

[0045] Furthermore, the third end of the four-way valve 38 is connected to the inlet of the nitrogen compressor 14 through the first regulating valve 22, the lower tower reboiler 7, the fourth regulating valve 23, the shell side of the top condenser 6, the precooler third raw gas inlet 36 of the precooler 2, the precooler third raw gas outlet 42 and the first three-way valve 37 in sequence, and an air intake pipeline with a nitrogen raw material storage tank 45 is provided between the first three-way valve 37 and the inlet of the nitrogen compressor 14.

[0046] Furthermore, the fourth end of the four-way 38 is connected to the third end of the first three-way 37 through the nitrogen expansion compressor 15, the main heat exchanger raw material inlet 39 and the main heat exchanger raw material outlet 49 of the main heat exchanger 3 in sequence.

[0047] Furthermore, the cold supply system includes an R23 refrigerant tank 13 , the outlet of which is connected to the inlet of the R23 refrigerant tank 13 via a third regulating valve 24 , a precooler raw material inlet 35 of the precooler 2 , a precooler raw material outlet 48 and an R23 compressor 12 .

[0048] A production process for a production device for producing ultrapure oxygen and liquid nitrogen using a precooling system, the production process comprising the following steps:

[0049] Step 1: The raw oxygen in the oxygen raw material storage tank 1 is precooled by the precooler 2, enters the main heat exchanger 3 to continue cooling, and enters the lower tower distillation tower 4 through the first raw liquid inlet 27 in the lower tower distillation tower 4; the temperature of the raw oxygen is: 20-30°C, the pressure is: 0.5Mpa, the flow rate is: 5000Nm / h, the gas phase fraction is: 1, and the oxygen molar fraction is: 99.5-99.6%;

[0050] Step 2: subjecting the raw material liquid entering the lower distillation tower 4 in step 1 to a distillation purification, and the gas phase after distillation purification enters the upper tower reboiler 8 and the upper distillation tower 5 respectively through the second three-way 47; the gas phase outlet temperature at the top of the lower distillation tower 4 is: -175 to -177°C, and the oxygen molar fraction is: 99.9 to 99.95%;

[0051] Step 3: The gas phase in step 2 enters the upper distillation tower 5 and then undergoes secondary distillation. The liquid phase after the secondary distillation enters the ultrapure oxygen storage tank 9 through the liquid phase outlet 31 of the upper distillation tower, and then enters the filling row 11 through the filling pump 10; the liquid phase temperature after the secondary distillation is: -181 to -183°C, and the molar purity of the ultrapure oxygen is not less than 99.9999%;

[0052] Step 4: the liquid phase after the primary distillation of the lower distillation tower 4 in step 2 enters the liquid oxygen atmospheric pressure storage tank 16 through the liquid phase outlet at the bottom of the lower distillation tower 4 and the ninth regulating valve 26 for industrial oxygen recovery;

[0053] Step 5: The gas phase after the secondary rectification in step 3 is liquefied through the tube heat exchange of the top condenser 6 and enters the third tee 50, and a part of it enters the upper distillation tower 5 through the tenth regulating valve 20 and the upper distillation tower raw liquid inlet 29 for reflux; the temperature at the upper distillation tower raw liquid inlet 29 is -181.5 to -183.5°C; the other part enters the fourth tee 51 through the shortcut pipeline 52; the material passing through the upper tower reboiler 8 in step 2 enters the fourth tee 51; the above two are combined in the fourth tee 51 and refluxed to the lower distillation tower 4 through the second raw liquid inlet 32 ​​of the lower distillation tower;

[0054] Step 6: The refrigerant R23 in the R23 refrigerant tank 13 is throttled through the third regulating valve 24, and after throttling, it is reheated through the precooler raw material inlet 35 and the precooler raw material outlet 48 of the precooler 2, and after reheating, it enters the R23 refrigerant tank 13 through the R23 compressor 12 and the inlet of the R23 refrigerant tank 13; the temperature at the inlet of the R23 compressor 12 is: -48 to -50 ° C, and the mole fraction of R23 is: 100%;

[0055] Step 7: The compressed nitrogen at the outlet of the nitrogen compressor 14 enters the liquid nitrogen atmospheric pressure storage tank 17 through the four-way 38 and the precooler second raw gas inlet 40 of the precooler 2, the precooler second raw gas outlet 30, the main heat exchanger second raw gas inlet 41 of the main heat exchanger 3, the main heat exchanger second raw gas outlet 33 and the second regulating valve 25 in sequence; the temperature of the main heat exchanger second raw gas outlet 33 is: -182~-184℃, and the pressure is: 0.01~0.03mPaG;

[0056] Step 8: The compressed nitrogen in the third end of the four-way in step 7 enters the lower tower reboiler 7 through the first regulating valve 22 and exchanges heat with the lower tower distillation tower 4. After the heat exchange, it is throttled by the fourth regulating valve 23 to the top condenser 6 to provide cooling capacity, and heat is exchanged again with the gas phase from the upper tower distillation tower 5 in the top condenser 6. After the heat exchange again, it passes through the shell side of the top condenser 6, the third raw gas inlet 36 of the precooler 2, the third raw gas outlet 42 of the precooler and the first three-way 37 to enter the nitrogen compressor 14 to form a cycle; the temperature of the third raw gas inlet 36 of the precooler 2 is: -184~-187℃, and the flow rate is: 4000~4200Nm 3 / h, gas phase fraction: 1; the temperature of the third raw gas outlet 42 of the precooler 2 is 30-35°C, and the pressure is: 1.3-1.5mPaG;

[0057] Step 9: The compressed nitrogen in the fourth end of the four-way in step 7 enters the main heat exchanger 3 through the nitrogen expander 15 to provide cooling capacity, and enters the nitrogen compressor 14 through the main heat exchanger raw material outlet 49 of the main heat exchanger 3 and the third end of the first three-way 37 for cyclic compression; the expander outlet pipeline temperature is: -183 ~ -185 ° C, pressure: 0.02 ~ 0.03mPaG;

[0058] Step 10: The raw nitrogen in the nitrogen raw material storage tank 45 is added to the liquid nitrogen preparation system through the air inlet pipeline; the specifications of the raw nitrogen are: 0.4MPaG / 25℃, 3500Nm 3 / h.

[0059] The present invention uses industrial-grade low-pressure oxygen as a raw material, adopts working fluid refrigeration to cool the raw oxygen and nitrogen for the first time, and realizes the liquefaction of oxygen and nitrogen after heat exchange with the cooling capacity of an expander; the liquefied oxygen is used in an ultra-pure oxygen device, and after upper and lower tower coupling distillation, an ultra-pure oxygen product is obtained. The quality of ultra-pure liquid oxygen products refers to the national standard GB / T 14599-2008 "Pure Oxygen, Ultrapure Oxygen and Ultrapure Oxygen" quality index ≥99.9999%. The advantages of the process method of the present invention are: 1. The raw oxygen and nitrogen are cooled for the first time by using R23 working medium refrigeration, and the oxygen and nitrogen are liquefied after heat exchange by the expansion machine, which saves energy consumption; 2. The ultra-pure oxygen device adopts the upper and lower tower coupling distillation technology to obtain ultra-pure oxygen products. The device occupies a small area, saves investment, and has a short payback period; 3. Both R23 working medium refrigeration and nitrogen circulation system are heat pump distillation technology, without exhaust gas emission, which is beneficial to atmospheric environmental protection, and is conducive to system stability, and product purity is guaranteed; 4. The energy of the present invention is highly integrated. Specifically, the top gas of the lower tower provides a heat source for the upper tower reboiler, reducing the load of the nitrogen compressor and reducing the energy consumption of the device; 5. The present invention also includes the design of a pre-cooling system, which can greatly reduce the circulation volume of the nitrogen compressor, thereby reducing the energy consumption per unit product, and is conducive to the balance of the system load and convenient operation.

[0060] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0061] Example 1

[0062] A production device for producing ultrapure oxygen and liquid nitrogen using a precooling system includes an ultrapure oxygen production system, wherein the ultrapure oxygen production system includes an oxygen raw material storage tank 1, which is connected to an ultrapure oxygen storage tank 9 through a raw material heat exchange unit and a thermally coupled distillation tower; a liquid nitrogen preparation system and a cold supply system respectively provide cold for the raw material heat exchange unit; and the liquid nitrogen preparation system respectively provides cold for the thermally coupled distillation tower and the top condenser 6 at the top of the thermally coupled distillation tower. The thermally coupled distillation tower includes a lower tower distillation tower 4 and an upper tower distillation tower 5 arranged at the top of the lower tower distillation tower 4; the outlet of the raw material heat exchange unit is connected to the first raw material liquid inlet 27 of the lower tower distillation tower in the lower tower distillation tower 4, the gas phase outlet at the top of the lower tower distillation tower 4 is respectively connected to the upper tower reboiler 8 and the first raw material gas inlet 34 of the upper tower distillation tower 5 through a second three-way 47, and the upper tower distillation tower liquid phase outlet 31 at the bottom of the upper tower distillation tower 5 is connected to the ultrapure oxygen storage tank 9. A fifth regulating valve 18 is provided between the second three-way valve 47 and the upper tower reboiler 8 , and a sixth regulating valve 19 is provided between the second three-way valve 47 and the upper tower distillation tower feed gas inlet 34 of the upper tower distillation tower 5 . The liquid phase outlet at the bottom of the lower tower distillation tower 4 is connected to the liquid oxygen atmospheric pressure storage tank 16 through the ninth regulating valve 26; the outlet of the upper tower reboiler 8 is connected to the second raw liquid inlet 32 ​​of the lower tower distillation tower at the upper part of the lower tower distillation tower 4; the gas phase outlet at the top of the upper tower distillation tower 5 is connected to the upper tower distillation tower raw liquid inlet 29 of the upper tower distillation tower 5 through the pipe line of the top condenser 6 and the tenth regulating valve 20; a seventh regulating valve 21 is provided between the liquid phase outlet at the bottom of the upper tower distillation tower 5 and the ultrapure oxygen storage tank 9, and the outlet of the ultrapure oxygen storage tank 9 is connected to the filling row 11 through the charging pump 10; a third three-way 50 is provided between the pipe line of the top condenser 6 and the tenth regulating valve 20, a fourth three-way 51 is provided between the outlet of the upper tower reboiler 8 and the second raw liquid inlet 32 ​​of the lower tower distillation tower, and a shortcut pipeline 52 is provided between the third end of the third three-way 50 and the third end of the fourth three-way 51. The raw material heat exchange unit includes a precooler 2 and a main heat exchanger 3. The oxygen raw material storage tank 1 is connected to the first raw liquid inlet 27 of the lower tower distillation tower through the first raw material gas inlet 28 of the precooler 2, the first raw material gas outlet 42 of the precooler, the first raw material gas inlet 43 of the main heat exchanger 3, the first raw material gas outlet 44 of the main heat exchanger and the eighth regulating valve 46. The liquid nitrogen preparation system includes a nitrogen compressor 14. The outlet of the nitrogen compressor 14 is connected to the second raw material gas inlet 40 of the precooler 2, the second raw material gas outlet 30 of the precooler, the second raw material gas inlet 41 of the main heat exchanger 3, the second raw material gas outlet 33 of the main heat exchanger and the second regulating valve 25 and the liquid nitrogen atmospheric pressure storage tank 17 through a four-way 38.The third end of the four-way 38 is connected to the inlet of the nitrogen compressor 14 through the first regulating valve 22, the lower tower reboiler 7, the fourth regulating valve 23, the shell side of the top condenser 6, the third raw material gas inlet 36 of the precooler 2, the third raw material gas outlet 42 of the precooler and the first three-way 37, and an air intake pipeline with a nitrogen raw material storage tank 45 is provided between the first three-way 37 and the inlet of the nitrogen compressor 14. The fourth end of the four-way 38 is connected to the third end of the first three-way 37 through the nitrogen expansion compressor 15, the main heat exchanger raw material inlet 39 of the main heat exchanger 3 and the main heat exchanger raw material outlet 49. The cold supply system includes an R23 refrigerant tank 13, and the outlet of the R23 refrigerant tank 13 is connected to the inlet of the R23 refrigerant tank 13 through the third regulating valve 24, the precooler raw material inlet 35 of the precooler 2, the precooler raw material outlet 48 and the R23 compressor 12.

[0063] A production process for a production device for producing ultrapure oxygen and liquid nitrogen using a precooling system, the production process comprising the following steps:

[0064] Step 1: The raw oxygen in the oxygen raw material storage tank 1 is precooled by the precooler 2, enters the main heat exchanger 3 to continue cooling, and enters the lower tower distillation tower 4 through the first raw liquid inlet 27 in the lower tower distillation tower 4; the temperature of the raw oxygen is: 20°C, the pressure is: 0.5Mpa, the flow rate is: 5000Nm / h, the gas phase fraction is: 1, and the oxygen molar fraction is: 99.5%;

[0065] Step 2: subjecting the raw material liquid entering the lower distillation tower 4 in step 1 to a distillation purification, and the gas phase after distillation purification enters the upper tower reboiler 8 and the upper distillation tower 5 respectively through the second three-way 47; the gas phase outlet temperature at the top of the lower distillation tower 4 is -175°C, and the oxygen molar fraction is 99.9%;

[0066] Step 3: The gas phase in step 2 enters the upper distillation tower 5 and then undergoes secondary distillation. The liquid phase after the secondary distillation enters the ultrapure oxygen storage tank 9 through the liquid phase outlet 31 of the upper distillation tower, and then enters the filling row 11 through the filling pump 10; the liquid phase temperature after the secondary distillation is: -183°C, and the molar purity of the ultrapure oxygen is not less than 99.9999%;

[0067] Step 4: the liquid phase after the primary distillation of the lower distillation tower 4 in step 2 enters the liquid oxygen atmospheric pressure storage tank 16 through the liquid phase outlet at the bottom of the lower distillation tower 4 and the ninth regulating valve 26 for industrial oxygen recovery;

[0068] Step 5: The gas phase after the secondary rectification in step 3 is liquefied through the tube heat exchange of the top condenser 6 and enters the third tee 50, and a part of it enters the upper distillation tower 5 through the tenth regulating valve 20 and the upper distillation tower raw liquid inlet 29 for reflux; the temperature at the upper distillation tower raw liquid inlet 29 is -183.5°C; the other part enters the fourth tee 51 through the shortcut pipeline 52; the material passing through the upper tower reboiler 8 in step 2 enters the fourth tee 51; the above two are combined in the fourth tee 51 and refluxed to the lower distillation tower 4 through the second raw liquid inlet 32 ​​of the lower distillation tower;

[0069] Step 6: The refrigerant R23 in the R23 refrigerant tank 13 is throttled through the third regulating valve 24, and after throttling, it is reheated through the precooler raw material inlet 35 and the precooler raw material outlet 48 of the precooler 2, and after reheating, it enters the R23 refrigerant tank 13 through the R23 compressor 12 and the inlet of the R23 refrigerant tank 13; the temperature at the inlet of the R23 compressor 12 is: -50°C, and the mole fraction of R23 is: 100%;

[0070] Step 7: The compressed nitrogen at the outlet of the nitrogen compressor 14 enters the liquid nitrogen atmospheric pressure storage tank 17 through the four-way 38 and the precooler second raw gas inlet 40 of the precooler 2, the precooler second raw gas outlet 30, the main heat exchanger second raw gas inlet 41 of the main heat exchanger 3, the main heat exchanger second raw gas outlet 33 and the second regulating valve 25 in sequence; the temperature of the main heat exchanger second raw gas outlet 33 is: -184°C, and the pressure is: 0.01mPaG;

[0071] Step 8: The compressed nitrogen in the third end of the four-way in step 7 enters the lower tower reboiler 7 through the first regulating valve 22 and exchanges heat with the lower tower distillation tower 4. After the heat exchange, it is throttled by the fourth regulating valve 23 to the top condenser 6 to provide cooling capacity. In the top condenser 6, it exchanges heat again with the gas phase from the upper tower distillation tower 5. After the heat exchange again, it passes through the shell side of the top condenser 6, the third raw gas inlet 36 of the precooler 2, the third raw gas outlet 42 of the precooler and the first three-way 37 to enter the nitrogen compressor 14 to form a cycle; the temperature of the third raw gas inlet 36 of the precooler 2 is: -187 ° C, and the flow rate is 4000Nm 3 / h, gas phase fraction: 1; the temperature of the third raw gas outlet 42 of the precooler 2 is 30°C, and the pressure is: 1.3mPaG;

[0072] Step 9: The compressed nitrogen in the fourth end of the four-way in step 7 enters the main heat exchanger 3 through the nitrogen expander 15 to provide cooling capacity, and enters the nitrogen compressor 14 through the main heat exchanger raw material outlet 49 of the main heat exchanger 3 and the third end of the first three-way 37 for cyclic compression; the expander outlet pipeline temperature is: -185°C, pressure: 0.02mPaG;

[0073] Step 10: The raw nitrogen in the nitrogen raw material storage tank 45 is added to the liquid nitrogen preparation system through the air inlet pipeline; the specifications of the raw nitrogen are: 0.4MPaG / 25℃, 3500Nm 3 / h.

[0074] Example 2

[0075] A production device for producing ultrapure oxygen and liquid nitrogen using a precooling system includes an ultrapure oxygen production system, wherein the ultrapure oxygen production system includes an oxygen raw material storage tank 1, which is connected to an ultrapure oxygen storage tank 9 through a raw material heat exchange unit and a thermally coupled distillation tower; a liquid nitrogen preparation system and a cold supply system respectively provide cold for the raw material heat exchange unit; and the liquid nitrogen preparation system respectively provides cold for the thermally coupled distillation tower and the top condenser 6 at the top of the thermally coupled distillation tower. The thermally coupled distillation tower includes a lower tower distillation tower 4 and an upper tower distillation tower 5 arranged at the top of the lower tower distillation tower 4; the outlet of the raw material heat exchange unit is connected to the first raw material liquid inlet 27 of the lower tower distillation tower in the lower tower distillation tower 4, the gas phase outlet at the top of the lower tower distillation tower 4 is respectively connected to the upper tower reboiler 8 and the first raw material gas inlet 34 of the upper tower distillation tower 5 through a second three-way 47, and the upper tower distillation tower liquid phase outlet 31 at the bottom of the upper tower distillation tower 5 is connected to the ultrapure oxygen storage tank 9. A fifth regulating valve 18 is provided between the second three-way valve 47 and the upper tower reboiler 8 , and a sixth regulating valve 19 is provided between the second three-way valve 47 and the upper tower distillation tower feed gas inlet 34 of the upper tower distillation tower 5 . The liquid phase outlet at the bottom of the lower tower distillation tower 4 is connected to the liquid oxygen atmospheric pressure storage tank 16 through the ninth regulating valve 26; the outlet of the upper tower reboiler 8 is connected to the second raw liquid inlet 32 ​​of the lower tower distillation tower at the upper part of the lower tower distillation tower 4; the gas phase outlet at the top of the upper tower distillation tower 5 is connected to the upper tower distillation tower raw liquid inlet 29 of the upper tower distillation tower 5 through the pipe line of the top condenser 6 and the tenth regulating valve 20; a seventh regulating valve 21 is provided between the liquid phase outlet at the bottom of the upper tower distillation tower 5 and the ultrapure oxygen storage tank 9, and the outlet of the ultrapure oxygen storage tank 9 is connected to the filling row 11 through the charging pump 10; a third three-way 50 is provided between the pipe line of the top condenser 6 and the tenth regulating valve 20, a fourth three-way 51 is provided between the outlet of the upper tower reboiler 8 and the second raw liquid inlet 32 ​​of the lower tower distillation tower, and a shortcut pipeline 52 is provided between the third end of the third three-way 50 and the third end of the fourth three-way 51. The raw material heat exchange unit includes a precooler 2 and a main heat exchanger 3. The oxygen raw material storage tank 1 is connected to the first raw liquid inlet 27 of the lower tower distillation tower through the first raw material gas inlet 28 of the precooler 2, the first raw material gas outlet 42 of the precooler, the first raw material gas inlet 43 of the main heat exchanger 3, the first raw material gas outlet 44 of the main heat exchanger and the eighth regulating valve 46. The liquid nitrogen preparation system includes a nitrogen compressor 14. The outlet of the nitrogen compressor 14 is connected to the second raw material gas inlet 40 of the precooler 2, the second raw material gas outlet 30 of the precooler, the second raw material gas inlet 41 of the main heat exchanger 3, the second raw material gas outlet 33 of the main heat exchanger and the second regulating valve 25 and the liquid nitrogen atmospheric pressure storage tank 17 through a four-way 38.The third end of the four-way 38 is connected to the inlet of the nitrogen compressor 14 through the first regulating valve 22, the lower tower reboiler 7, the fourth regulating valve 23, the shell side of the top condenser 6, the third raw material gas inlet 36 of the precooler 2, the third raw material gas outlet 42 of the precooler and the first three-way 37, and an air intake pipeline with a nitrogen raw material storage tank 45 is provided between the first three-way 37 and the inlet of the nitrogen compressor 14. The fourth end of the four-way 38 is connected to the third end of the first three-way 37 through the nitrogen expansion compressor 15, the main heat exchanger raw material inlet 39 of the main heat exchanger 3 and the main heat exchanger raw material outlet 49. The cold supply system includes an R23 refrigerant tank 13, and the outlet of the R23 refrigerant tank 13 is connected to the inlet of the R23 refrigerant tank 13 through the third regulating valve 24, the precooler raw material inlet 35 of the precooler 2, the precooler raw material outlet 48 and the R23 compressor 12.

[0076] A production process for a production device for producing ultrapure oxygen and liquid nitrogen using a precooling system, the production process comprising the following steps:

[0077] Step 1: The raw oxygen in the oxygen raw material storage tank 1 is precooled by the precooler 2, enters the main heat exchanger 3 to continue cooling, and enters the lower tower distillation tower 4 through the first raw liquid inlet 27 in the lower tower distillation tower 4; the temperature of the raw oxygen is: 30°C, the pressure is: 0.5Mpa, the flow rate is: 5000Nm / h, the gas phase fraction is: 1, and the oxygen molar fraction is: 99.6%;

[0078] Step 2: subjecting the raw material liquid entering the lower distillation tower 4 in step 1 to a distillation purification, and the gas phase after distillation purification enters the upper tower reboiler 8 and the upper distillation tower 5 respectively through the second three-way 47; the gas phase outlet temperature at the top of the lower distillation tower 4 is -177°C, and the oxygen molar fraction is 99.95%;

[0079] Step 3: The gas phase in step 2 enters the upper distillation tower 5 and then undergoes secondary distillation. The liquid phase after the secondary distillation enters the ultrapure oxygen storage tank 9 through the liquid phase outlet 31 of the upper distillation tower, and then enters the filling row 11 through the filling pump 10; the liquid phase temperature after the secondary distillation is: -181°C, and the molar purity of the ultrapure oxygen is not less than 99.9999%;

[0080] Step 4: the liquid phase after the primary distillation of the lower distillation tower 4 in step 2 enters the liquid oxygen atmospheric pressure storage tank 16 through the liquid phase outlet at the bottom of the lower distillation tower 4 and the ninth regulating valve 26 for industrial oxygen recovery;

[0081] Step 5: The gas phase after the secondary rectification in step 3 is liquefied through the tube heat exchange of the top condenser 6 and enters the third tee 50, and a part of it enters the upper distillation tower 5 through the tenth regulating valve 20 and the upper distillation tower raw liquid inlet 29 for reflux; the temperature at the upper distillation tower raw liquid inlet 29 is -181.5°C; the other part enters the fourth tee 51 through the shortcut pipeline 52; the material passing through the upper tower reboiler 8 in step 2 enters the fourth tee 51; the above two are combined in the fourth tee 51 and refluxed to the lower distillation tower 4 through the second raw liquid inlet 32 ​​of the lower distillation tower;

[0082] Step 6: The refrigerant R23 in the R23 refrigerant tank 13 is throttled through the third regulating valve 24, and after throttling, it is reheated through the precooler raw material inlet 35 and the precooler raw material outlet 48 of the precooler 2, and after reheating, it enters the R23 refrigerant tank 13 through the R23 compressor 12 and the inlet of the R23 refrigerant tank 13; the temperature at the inlet of the R23 compressor 12 is: -48°C, and the mole fraction of R23 is: 100%;

[0083] Step 7: The compressed nitrogen at the outlet of the nitrogen compressor 14 enters the liquid nitrogen atmospheric pressure storage tank 17 through the four-way 38 and the precooler second raw gas inlet 40 of the precooler 2, the precooler second raw gas outlet 30, the main heat exchanger second raw gas inlet 41 of the main heat exchanger 3, the main heat exchanger second raw gas outlet 33 and the second regulating valve 25 in sequence; the temperature of the main heat exchanger second raw gas outlet 33 is: -182°C, and the pressure is: 0.03mPaG;

[0084] Step 8: The compressed nitrogen in the third end of the four-way in step 7 enters the lower tower reboiler 7 through the first regulating valve 22 and exchanges heat with the lower tower distillation tower 4. After the heat exchange, it is throttled by the fourth regulating valve 23 to the top condenser 6 to provide cooling capacity, and heat is exchanged again with the gas phase from the upper tower distillation tower 5 in the top condenser 6. After the heat exchange again, it passes through the shell side of the top condenser 6, the third raw gas inlet 36 of the precooler 2, the third raw gas outlet 42 of the precooler and the first three-way 37 to enter the nitrogen compressor 14 to form a cycle; the temperature of the third raw gas inlet 36 of the precooler 2 is: -184~-187℃, and the flow rate is 4200Nm 3 / h, gas phase fraction: 1; the temperature of the third raw gas outlet 42 of the precooler 2 is 35°C, and the pressure is: 1.5mPaG;

[0085] Step 9: The compressed nitrogen in the fourth end of the four-way in step 7 enters the main heat exchanger 3 through the nitrogen expander 15 to provide cooling capacity, and enters the nitrogen compressor 14 through the main heat exchanger raw material outlet 49 of the main heat exchanger 3 and the third end of the first three-way 37 for cyclic compression; the expander outlet pipeline temperature is: -183°C, pressure: 0.03mPaG;

[0086] Step 10: The raw nitrogen in the nitrogen raw material storage tank 45 is added to the liquid nitrogen preparation system through the air inlet pipeline; the specifications of the raw nitrogen are: 0.4MPaG / 25℃, 3500Nm 3 / h.

[0087] Example 3

[0088] A production device for producing ultrapure oxygen and liquid nitrogen using a precooling system includes an ultrapure oxygen production system, wherein the ultrapure oxygen production system includes an oxygen raw material storage tank 1, which is connected to an ultrapure oxygen storage tank 9 through a raw material heat exchange unit and a thermally coupled distillation tower; a liquid nitrogen preparation system and a cold supply system respectively provide cold for the raw material heat exchange unit; and the liquid nitrogen preparation system respectively provides cold for the thermally coupled distillation tower and the top condenser 6 at the top of the thermally coupled distillation tower. The thermally coupled distillation tower includes a lower tower distillation tower 4 and an upper tower distillation tower 5 arranged at the top of the lower tower distillation tower 4; the outlet of the raw material heat exchange unit is connected to the first raw material liquid inlet 27 of the lower tower distillation tower in the lower tower distillation tower 4, the gas phase outlet at the top of the lower tower distillation tower 4 is respectively connected to the upper tower reboiler 8 and the first raw material gas inlet 34 of the upper tower distillation tower 5 through a second three-way 47, and the upper tower distillation tower liquid phase outlet 31 at the bottom of the upper tower distillation tower 5 is connected to the ultrapure oxygen storage tank 9. A fifth regulating valve 18 is provided between the second three-way valve 47 and the upper tower reboiler 8 , and a sixth regulating valve 19 is provided between the second three-way valve 47 and the upper tower distillation tower feed gas inlet 34 of the upper tower distillation tower 5 . The liquid phase outlet at the bottom of the lower tower distillation tower 4 is connected to the liquid oxygen atmospheric pressure storage tank 16 through the ninth regulating valve 26; the outlet of the upper tower reboiler 8 is connected to the second raw liquid inlet 32 ​​of the lower tower distillation tower at the upper part of the lower tower distillation tower 4; the gas phase outlet at the top of the upper tower distillation tower 5 is connected to the upper tower distillation tower raw liquid inlet 29 of the upper tower distillation tower 5 through the pipe line of the top condenser 6 and the tenth regulating valve 20; a seventh regulating valve 21 is provided between the liquid phase outlet at the bottom of the upper tower distillation tower 5 and the ultrapure oxygen storage tank 9, and the outlet of the ultrapure oxygen storage tank 9 is connected to the filling row 11 through the charging pump 10; a third three-way 50 is provided between the pipe line of the top condenser 6 and the tenth regulating valve 20, a fourth three-way 51 is provided between the outlet of the upper tower reboiler 8 and the second raw liquid inlet 32 ​​of the lower tower distillation tower, and a shortcut pipeline 52 is provided between the third end of the third three-way 50 and the third end of the fourth three-way 51. The raw material heat exchange unit includes a precooler 2 and a main heat exchanger 3. The oxygen raw material storage tank 1 is connected to the first raw liquid inlet 27 of the lower tower distillation tower through the first raw material gas inlet 28 of the precooler 2, the first raw material gas outlet 42 of the precooler, the first raw material gas inlet 43 of the main heat exchanger 3, the first raw material gas outlet 44 of the main heat exchanger and the eighth regulating valve 46. The liquid nitrogen preparation system includes a nitrogen compressor 14. The outlet of the nitrogen compressor 14 is connected to the second raw material gas inlet 40 of the precooler 2, the second raw material gas outlet 30 of the precooler, the second raw material gas inlet 41 of the main heat exchanger 3, the second raw material gas outlet 33 of the main heat exchanger and the second regulating valve 25 and the liquid nitrogen atmospheric pressure storage tank 17 through a four-way 38.The third end of the four-way 38 is connected to the inlet of the nitrogen compressor 14 through the first regulating valve 22, the lower tower reboiler 7, the fourth regulating valve 23, the shell side of the top condenser 6, the third raw material gas inlet 36 of the precooler 2, the third raw material gas outlet 42 of the precooler and the first three-way 37, and an air intake pipeline with a nitrogen raw material storage tank 45 is provided between the first three-way 37 and the inlet of the nitrogen compressor 14. The fourth end of the four-way 38 is connected to the third end of the first three-way 37 through the nitrogen expansion compressor 15, the main heat exchanger raw material inlet 39 of the main heat exchanger 3 and the main heat exchanger raw material outlet 49. The cold supply system includes an R23 refrigerant tank 13, and the outlet of the R23 refrigerant tank 13 is connected to the inlet of the R23 refrigerant tank 13 through the third regulating valve 24, the precooler raw material inlet 35 of the precooler 2, the precooler raw material outlet 48 and the R23 compressor 12.

[0089] A production process for a production device for producing ultrapure oxygen and liquid nitrogen using a precooling system, the production process comprising the following steps:

[0090] Step 1: The raw oxygen in the oxygen raw material storage tank 1 is precooled by the precooler 2, enters the main heat exchanger 3 to continue cooling, and enters the lower tower distillation tower 4 through the first raw liquid inlet 27 in the lower tower distillation tower 4; the temperature of the raw oxygen is: 25°C, the pressure is: 0.5Mpa, the flow rate is: 5000Nm / h, the gas phase fraction is: 1, and the oxygen molar fraction is: 99.55%;

[0091] Step 2: subjecting the raw material liquid entering the lower distillation tower 4 in step 1 to a distillation purification, and the gas phase after distillation purification enters the upper tower reboiler 8 and the upper distillation tower 5 respectively through the second three-way 47; the gas phase outlet temperature at the top of the lower distillation tower 4 is -176°C, and the oxygen molar fraction is 99.93%;

[0092] Step 3: The gas phase in step 2 enters the upper distillation tower 5 and then undergoes secondary distillation. The liquid phase after the secondary distillation enters the ultrapure oxygen storage tank 9 through the liquid phase outlet 31 of the upper distillation tower, and then enters the filling row 11 through the filling pump 10; the liquid phase temperature after the secondary distillation is: -182°C, and the molar purity of the ultrapure oxygen is not less than 99.9999%;

[0093] Step 4: the liquid phase after the primary distillation of the lower distillation tower 4 in step 2 enters the liquid oxygen atmospheric pressure storage tank 16 through the liquid phase outlet at the bottom of the lower distillation tower 4 and the ninth regulating valve 26 for industrial oxygen recovery;

[0094] Step 5: The gas phase after the secondary rectification in step 3 is liquefied through the tube heat exchange of the top condenser 6 and enters the third tee 50, and a part of it enters the upper distillation tower 5 through the tenth regulating valve 20 and the upper distillation tower raw liquid inlet 29 for reflux; the temperature at the upper distillation tower raw liquid inlet 29 is -182.5°C; the other part enters the fourth tee 51 through the shortcut pipeline 52; the material passing through the upper tower reboiler 8 in step 2 enters the fourth tee 51; the above two are combined in the fourth tee 51 and refluxed to the lower distillation tower 4 through the second raw liquid inlet 32 ​​of the lower distillation tower;

[0095] Step 6: The refrigerant R23 in the R23 refrigerant tank 13 is throttled through the third regulating valve 24, and after throttling, it is reheated through the precooler raw material inlet 35 and the precooler raw material outlet 48 of the precooler 2, and after reheating, it enters the R23 refrigerant tank 13 through the R23 compressor 12 and the inlet of the R23 refrigerant tank 13; the temperature at the inlet of the R23 compressor 12 is: -49°C, and the mole fraction of R23 is: 100%;

[0096] Step 7: The compressed nitrogen at the outlet of the nitrogen compressor 14 enters the liquid nitrogen atmospheric pressure storage tank 17 through the four-way 38 and the precooler second raw gas inlet 40 of the precooler 2, the precooler second raw gas outlet 30, the main heat exchanger second raw gas inlet 41 of the main heat exchanger 3, the main heat exchanger second raw gas outlet 33 and the second regulating valve 25 in sequence; the temperature of the main heat exchanger second raw gas outlet 33 is: -183°C, and the pressure is: 0.02mPaG;

[0097] Step 8: The compressed nitrogen in the third end of the four-way in step 7 enters the lower tower reboiler 7 through the first regulating valve 22 and exchanges heat with the lower tower distillation tower 4. After the heat exchange, it is throttled by the fourth regulating valve 23 to the top condenser 6 to provide cooling capacity. In the top condenser 6, it exchanges heat again with the gas phase from the upper tower distillation tower 5. After the heat exchange again, it passes through the shell side of the top condenser 6, the third raw gas inlet 36 of the precooler 2, the third raw gas outlet 42 of the precooler and the first three-way 37 to enter the nitrogen compressor 14 to form a cycle; the temperature of the third raw gas inlet 36 of the precooler 2 is: -185.5 ° C, and the flow rate is: 4100Nm 3 / h, gas phase fraction: 1; the temperature of the third raw gas outlet 42 of the precooler 2 is 32.5°C, and the pressure is: 1.4mPaG;

[0098] Step 9: The compressed nitrogen in the fourth end of the four-way in step 7 enters the main heat exchanger 3 through the nitrogen expander 15 to provide cooling capacity, and enters the nitrogen compressor 14 through the main heat exchanger raw material outlet 49 of the main heat exchanger 3 and the third end of the first three-way 37 for cyclic compression; the expander outlet pipeline temperature is: -184°C, pressure: 0.025mPaG;

[0099] Step 10: The raw nitrogen in the nitrogen raw material storage tank 45 is added to the liquid nitrogen preparation system through the air inlet pipeline; the specifications of the raw nitrogen are: 0.4MPaG / 25℃, 3500Nm 3 / h.

[0100] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connection", "connected" and the like should be understood in a broad sense. For example, it can be a fixed connection, an integral connection, or a detachable connection; it can also be the internal connection of two elements; it can be a direct connection, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The above examples are only specific descriptions of the feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent implementation methods, changes and modifications that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A production device for producing ultrapure oxygen and liquid nitrogen using a precooling system, characterized in that: The production unit includes an ultra-pure oxygen production system, The ultrapure oxygen production system comprises an oxygen raw material storage tank (1), wherein the oxygen raw material storage tank (1) is connected to an ultrapure oxygen storage tank (9) via a raw material heat exchange unit and a thermally coupled distillation tower; The liquid nitrogen preparation system and the cold supply system provide cold capacity for the raw material heat exchange unit respectively; The liquid nitrogen preparation system provides cooling capacity for the thermally coupled distillation tower and the top condenser (6) at the top of the thermally coupled distillation tower; The thermally coupled distillation tower comprises a lower distillation tower (4) and an upper distillation tower (5) arranged on the top of the lower distillation tower (4); The outlet of the raw material heat exchange unit is connected to the first raw material liquid inlet (27) of the lower distillation tower in the lower distillation tower (4); the gas phase outlet at the top of the lower distillation tower (4) is connected to the upper tower reboiler (8) and the upper tower distillation tower raw material gas inlet (34) of the upper distillation tower (5) through the second tee (47); the upper tower distillation tower liquid phase outlet (31) at the bottom of the upper distillation tower (5) is connected to the ultrapure oxygen storage tank (9); A fifth regulating valve (18) is provided between the second three-way valve (47) and the upper tower reboiler (8), and a sixth regulating valve (19) is provided between the second three-way valve (47) and the upper tower distillation tower feed gas inlet (34) of the upper tower distillation tower (5); The liquid phase outlet at the bottom of the lower distillation tower (4) is connected to the liquid oxygen atmospheric pressure storage tank (16) via a ninth regulating valve (26); The outlet of the upper tower reboiler (8) is connected to the second raw liquid inlet (32) of the lower tower distillation tower at the upper part of the lower tower distillation tower (4); The gas phase outlet at the top of the upper distillation tower (5) is connected to the upper distillation tower raw liquid inlet (29) of the upper distillation tower (5) through the pipe line of the top condenser (6) and the tenth regulating valve (20); A seventh regulating valve (21) is provided between the liquid phase outlet at the bottom of the upper distillation tower (5) and the ultrapure oxygen storage tank (9), and the outlet of the ultrapure oxygen storage tank (9) is connected to the filling row (11) via a filling pump (10); A third three-way valve (50) is provided between the pipe side of the top condenser (6) and the tenth regulating valve (20), a fourth three-way valve (51) is provided between the outlet of the upper tower reboiler (8) and the inlet (32) of the second raw liquid of the lower tower rectification tower, and a shortcut pipeline (52) is provided between the third end of the third three-way valve (50) and the third end of the fourth three-way valve (51); The raw material heat exchange unit comprises a precooler (2) and a main heat exchanger (3); the oxygen raw material storage tank (1) is connected to the first raw material liquid inlet (27) of the lower distillation tower via a precooler first raw material gas inlet (28) of the precooler (2), a first raw material gas outlet of the precooler, a main heat exchanger first raw material gas inlet (43) of the main heat exchanger (3), a main heat exchanger first raw material gas outlet (44) and an eighth regulating valve (46); The liquid nitrogen preparation system comprises a nitrogen compressor (14), wherein the outlet of the nitrogen compressor (14) is connected in sequence to a precooler second raw gas inlet (40) of a precooler (2), a precooler second raw gas outlet (30), a main heat exchanger second raw gas inlet (41) of a main heat exchanger (3), a main heat exchanger second raw gas outlet (33), a second regulating valve (25), and a liquid nitrogen atmospheric pressure storage tank (17) through a four-way valve (38); The third end of the four-way valve (38) is connected to the inlet of the nitrogen compressor (14) through the first regulating valve (22), the lower tower reboiler (7), the fourth regulating valve (23), the shell side of the top condenser (6), the third raw gas inlet (36) of the precooler (2), the third raw gas outlet of the precooler and the first three-way valve (37) in sequence, and an air intake pipeline with a nitrogen raw material storage tank (45) is provided between the first three-way valve (37) and the inlet of the nitrogen compressor (14); The fourth end of the four-way (38) is connected to the third end of the first three-way (37) via the nitrogen expander (15), the main heat exchanger raw material inlet (39) and the main heat exchanger raw material outlet (49) of the main heat exchanger (3); The cold supply system comprises an R23 refrigerant tank (13), wherein the outlet of the R23 refrigerant tank (13) is connected to the inlet of the R23 refrigerant tank (13) via a third regulating valve (24), a precooler raw material inlet (35) of the precooler (2), a precooler raw material outlet (48) and an R23 compressor (12).

2. A production process using the production device for producing ultrapure oxygen and liquid nitrogen using a precooling system as claimed in claim 1, characterized in that: The production process includes the following steps: Step 1: The raw oxygen in the oxygen raw material storage tank (1) is precooled by the precooler (2), enters the main heat exchanger (3) to continue cooling, and enters the lower tower distillation tower (4) through the first raw liquid inlet (27) in the lower tower distillation tower (4); the raw oxygen has a temperature of 20 to 30°C, a pressure of 0.5 MPa, a flow rate of 5000 Nm / h, a gas phase fraction of 1, and an oxygen molar fraction of 99.5 to 99.6%; Step 2: subjecting the raw material liquid entering the lower distillation tower (4) in step 1 to a distillation purification, and the gas phase after distillation purification enters the upper tower reboiler (8) and the upper distillation tower (5) respectively through the second three-way (47); the gas phase outlet temperature at the top of the lower distillation tower 4 is: -175 to -177°C, and the oxygen molar fraction is: 99.9 to 99.95%; Step 3: The gas phase in step 2 enters the upper distillation tower (5) and undergoes secondary distillation. The liquid phase after the secondary distillation enters the ultrapure oxygen storage tank (9) through the liquid phase outlet (31) of the upper distillation tower, and then enters the filling row (11) through the filling pump (10); the liquid phase temperature after the secondary distillation is: -181 to -183°C, and the molar purity of the ultrapure oxygen is not less than 99.9999%; Step 4: the liquid phase after the primary distillation in the lower distillation tower (4) in step 2 enters the liquid oxygen atmospheric pressure storage tank (16) through the liquid phase outlet at the bottom of the lower distillation tower (4) and the ninth regulating valve (26) for industrial oxygen recovery; Step 5: The gas phase after the secondary distillation in step 3 is liquefied through the heat exchange of the tube side of the top condenser (6) and enters the third tee (50), and a part of it enters the upper distillation tower (5) through the tenth regulating valve (20) and the raw liquid inlet (29) of the upper distillation tower for reflux; the temperature at the raw liquid inlet (29) of the upper distillation tower is -181.5 to -183.5°C; the other part enters the fourth tee (51) through the shortcut pipeline (52); the material passing through the upper tower reboiler (8) in step 2 enters the fourth tee (51); the above two are merged in the fourth tee (51) and refluxed to the lower distillation tower (4) through the second raw liquid inlet (32) of the lower distillation tower; Step 6: The refrigerant R23 in the R23 refrigerant tank (13) is throttled through the third regulating valve (24), and after throttling, it is reheated through the precooler raw material inlet (35) and the precooler raw material outlet (48) of the precooler (2), and after reheating, it enters the R23 refrigerant tank (13) through the R23 compressor (12) and the inlet of the R23 refrigerant tank (13); the temperature at the inlet of the R23 compressor (12) is: -48 to -50°C, and the mole fraction of R23 is: 100%; Step 7: The compressed nitrogen at the outlet of the nitrogen compressor (14) enters the liquid nitrogen atmospheric pressure storage tank (17) through the four-way (38) and the precooler second raw gas inlet (40) of the precooler (2), the precooler second raw gas outlet (30), the main heat exchanger second raw gas inlet (41) of the main heat exchanger (3), the main heat exchanger second raw gas outlet (33) and the second regulating valve (25); the temperature of the main heat exchanger second raw gas outlet (33) is: -182 to -184°C, and the pressure is: 0.01 to 0.03 mPaG; Step 8: The compressed nitrogen in the third end of the four-way in step 7 enters the lower tower reboiler (7) through the first regulating valve (22) to exchange heat with the lower tower distillation tower (4), and after heat exchange, passes through the fourth regulating valve (23) to throttle to the top condenser (6) to provide cooling capacity, and in the top condenser (6) it exchanges heat again with the gas phase from the upper tower distillation tower (5), and after the heat exchange again, it passes through the shell side of the top condenser (6), the third raw gas inlet (36) of the precooler (2), the third raw gas outlet of the precooler and the first three-way (37) to enter the nitrogen compressor (14) to form a cycle; the temperature of the third raw gas inlet (36) of the precooler (2) is: -184~-187℃, and the flow rate is: 4000~4200Nm 3 / h, gas phase fraction: 1; the outlet temperature of the third raw gas of the precooler (2) is 30-35°C, and the pressure is: 1.3-1.5mPaG; Step 9: The compressed nitrogen in the fourth end of the four-way pipe in step 7 enters the main heat exchanger (3) through the nitrogen expander (15) to provide cooling capacity for the main heat exchanger (3), and enters the nitrogen compressor (14) through the main heat exchanger raw material outlet (49) of the main heat exchanger (3) and the third end of the first three-way pipe (37) for cyclic compression; the expander outlet pipeline temperature is: -183 to -185°C, and the pressure is: 0.02 to 0.03 mPaG; Step 10: The raw nitrogen in the nitrogen raw material storage tank (45) is added to the liquid nitrogen preparation system through the air inlet pipeline; the specifications of the raw nitrogen are: 0.4MPaG / 25℃, 3500Nm 3 / h.

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