Device and method for purifying nitric oxide gas

Abstract

The invention relates to a nitric oxide gas purification method which comprises the following steps: introducing crude nitric oxide gas into an extraction tower, and introducing an extraction phase obtained after extraction into a desorption tower for heating desorption; the desorbed nitric oxide gas passes through an alkaline washing tower and a condenser and then is introduced into an ethanol absorption tower; introducing into an adsorption tower filled with a 13X molecular sieve; the adsorbed gas is collected into a product collecting bottle, and a nitric oxide product with the purity larger than 99.99% is obtained. According to the method, a ferrous sulfate solution is used as an extracting agent to extract and refine nitric oxide, efficient extraction of nitric oxide is achieved through coordination reaction of ferrous ions and nitric oxide in the purification process, then ethyl alcohol is used as an absorbent, and nitric oxide and nitrous oxide are extracted and purified by means of the remarkable solubility difference of nitric oxide and nitrous oxide in ethyl alcohol. Nitrous oxide impurities which are difficult to remove can be selectively absorbed, and finally, the 13X molecular sieve is used for further deeply removing nitrous oxide, so that disproportionation reaction is favorably reduced, and the product purity is improved.

Description

Technical Field

[0001] The present invention relates to the field of gas purification, and in particular to a device and method for purifying nitric oxide gas. Background Art

[0002] Nitric oxide is a permanent gas that is colorless, odorless, slightly soluble in water, soluble in solvents such as ethanol and carbon disulfide, and appears blue in liquid or solid state at low temperatures. Nitric oxide is widely used in many fields such as fine chemicals, environmental protection, medical treatment, scientific research, and electronics. For example, it is used in the preparation of nitric acid and nitration processes in the chemical industry, as an emergency abort agent in the polyvinyl chloride industry, and as a propellant for space rockets and satellites. In recent years, with the rapid development of the semiconductor industry, the demand for nitric oxide has grown rapidly because it can be used in the formation, oxidation, and chemical vapor deposition of silicon oxide films, and the requirements for purity are constantly increasing. The demand for high-purity (99.99%) nitric oxide gas is in short supply.

[0003] Patent CN108163823A discloses a method for preparing 4N purity nitric oxide gas, including adding dilute sulfuric acid to sodium nitrite solution to generate crude nitric oxide, after alkali washing, dehydration, primary drying, the gas after primary drying is sequentially passed through modified molecular sieves C2 and C5 for deep drying, and then subjected to adsorption treatment by a cryogenic adsorber, a product with 4N purity can be collected; the modification process of the modified molecular sieves C2 and C5 is: immersing the molecular sieves C2 and C5 in a nitric acid solution with a concentration of 10%, taking them out after 24 hours, and activating and drying them at 300°C for 8 hours. Patent CN118651826A discloses a method for refining nitric oxide gas, in which the reaction raw materials dilute sulfuric acid and a saturated sodium nitrite solution are added to a synthesis reactor to generate crude nitric oxide gas; the crude nitric oxide gas is sequentially subjected to alkali washing and condensation to remove water, and finally subjected to three-stage adsorption under cryogenic conditions to obtain nitric oxide gas with a purity of not less than 99.99%.

[0004] In the above patent, during the preparation of nitric oxide, nitric oxide will undergo a disproportionation reaction, resulting in a decrease in the yield of nitric oxide. At the same time, multi-stage adsorption will also promote the disproportionation reaction of nitric oxide gas to produce nitrogen dioxide and nitrous oxide, affecting the purity and yield of the product.

[0005] Therefore, it is necessary to invent a simple, safe and efficient method and device for purifying nitric oxide gas to improve the purity and yield of nitric oxide gas. Summary of the invention

[0006] In order to overcome the above problems existing in the prior art, the object of the present invention is to provide a nitric oxide gas purification device and method, which can simply, economically and efficiently remove impurities in crude nitric oxide gas while reducing the loss of nitric oxide gas.

[0007] To achieve the purpose of the present invention, the specific technical solutions provided by the present invention are as follows:

[0008] A device for purifying nitric oxide gas comprises an extraction tower, a decomposition tower, an alkali washing tower, a condenser, an ethanol absorption tower and an adsorption tower which are connected in sequence;

[0009] The extraction tower is provided with an extraction tower feed port in the middle, and an extraction tower discharge port at the bottom;

[0010] The middle position of the analytical tower is provided with an analytical tower feed port, and the top position is provided with an analytical tower discharge port;

[0011] The bottom of the alkali washing tower is provided with an alkali washing tower feed port, and the top of the alkali washing tower is provided with an alkali washing tower discharge port;

[0012] The condenser is provided with a condenser feed port at one end and a condenser discharge port at the other end;

[0013] The bottom of the ethanol absorption tower is provided with an ethanol absorption tower feed port, and the top of the ethanol absorption tower is provided with an ethanol absorption tower discharge port;

[0014] The adsorption tower bottom is provided with an adsorption tower feed port, and the adsorption tower top is provided with an adsorption tower discharge port;

[0015] The extraction tower feed port is connected to the crude gas source pipeline, the extraction tower discharge port is connected to the analysis tower feed port pipeline, the analysis tower discharge port is connected to the alkali washing tower feed port pipeline, the alkali washing tower discharge port is connected to the condenser feed port pipeline, the condenser discharge port is connected to the ethanol absorption tower feed port pipeline, the ethanol absorption tower discharge port is connected to the adsorption tower feed port pipeline, and the adsorption tower discharge port is connected to the product collection unit pipeline.

[0016] Preferably, the ratio of the diameter to the height of the extraction tower is 38:4800, and an extractant inlet is also provided at the top of the extraction tower, the extractant inlet is connected to the extractant tank, and the amount of extractant added is 1 / 4 to 1 / 3 of the volume of the extraction tower.

[0017] Preferably, the ratio of the diameter to the height of the analytical tower is 38:4800, a kettle heater is provided at the bottom of the analytical tower, an extractant outlet is also provided at the bottom of the analytical tower, and the extractant outlet of the analytical tower is connected to an extractant recovery tank.

[0018] Preferably, the ratio of the diameter to the height of the alkali washing tower is 1:30, and the interior of the alkali washing tower is filled with a sodium hydroxide solution, and the amount of the sodium hydroxide solution added is 1 / 3 to 2 / 3 of the volume of the alkali washing tower.

[0019] Preferably, the condenser is further provided with a refrigerant inlet and a refrigerant outlet, and the refrigerant inlet and the refrigerant outlet are respectively connected to the refrigerant storage tank.

[0020] Preferably, the ratio of the diameter to the height of the ethanol absorption tower is 1:30, the interior of the ethanol absorption tower is filled with anhydrous ethanol, the amount of anhydrous ethanol added is 1 / 3 to 2 / 3 of the volume of the ethanol absorption tower, the ratio of the diameter to the height of the adsorption tower is 45:1000, and the interior of the adsorption tower is filled with 13X molecular sieve.

[0021] Preferably, a first valve is provided on the connecting pipe between the crude gas source and the extraction tower, a second valve is provided on the connecting pipe between the extraction tower and the decomposition tower, a third valve is provided on the connecting pipe between the decomposition tower and the alkali washing tower, a fourth valve is provided on the connecting pipe between the alkali washing tower and the condenser, a fifth valve is provided on the connecting pipe between the condenser and the ethanol absorption tower, a sixth valve is provided on the connecting pipe between the ethanol absorption tower and the adsorption tower, and a seventh valve is provided on the connecting pipe between the adsorption tower and the product collection unit.

[0022] The present invention also provides a method for purifying nitric oxide gas, which is implemented by a device for purifying nitric oxide gas, comprising the following steps:

[0023] The crude nitric oxide gas is introduced into an extraction tower, and an extractant is delivered from an extractant inlet at the upper end of the extraction tower. The extraction phase obtained after the extraction is completed is introduced into a decomposition tower for heating and decomposition, and the extractant is recovered from an extractant outlet at the bottom of the decomposition tower; the decomposed nitric oxide gas is introduced into an ethanol absorption tower after passing through an alkali washing tower and a condenser; the gas absorbed by ethanol in the ethanol absorption tower is introduced into an adsorption tower filled with 13X molecular sieve; the gas after adsorption is collected in a product collection bottle to obtain a nitric oxide product with a purity greater than 99.99%.

[0024] Preferably, the flow rate of the crude nitric oxide gas introduced into the extraction tower is 5-10 L / min, the extractant in the extraction tower is ferrous sulfate solution, and the concentration of the ferrous sulfate solution is 1-1.3 mol / L.

[0025] Preferably, the temperature of the extract phase is raised to 100-120°C when it is analyzed in the analysis tower; the inside of the alkali washing tower is filled with a sodium hydroxide solution with a mass concentration of 5%; the refrigerant in the condenser is dichloromethane, and the refrigerant temperature is -30°C.

[0026] The nitric oxide gas purification device and method of the present invention have the following beneficial effects:

[0027] 1. The present invention adopts ferrous sulfate solution as an extractant, and realizes efficient extraction of nitric oxide through the coordination reaction between ferrous ions and nitric oxide. This method not only reduces the occurrence of disproportionation reaction, but also improves the extraction efficiency, reduces the loss of nitric oxide gas, and lays a good foundation for subsequent purification steps.

[0028] 2. In the purification process, the present invention innovatively uses ethanol as an absorbent. By utilizing the significant difference in solubility between nitric oxide and nitrous oxide in ethanol, the present invention can selectively absorb the nitrous oxide impurity which is difficult to remove. In addition, by further using 13X molecular sieve for deep removal, the present invention successfully reduces the nitrous oxide content in the product to an extremely low level, thereby significantly improving the purity of the product.

[0029] 3. The purification device of the present invention is reasonably designed, and the components are tightly connected, which reduces the possibility of gas leakage. At the same time, by recycling the extractant and using renewable ethanol as an absorbent, the present invention reduces production costs and reduces environmental pollution. In addition, the dichloromethane refrigerant used in the condenser also has high environmental protection performance, which meets the green requirements of modern industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of a nitric oxide gas purification device of the present invention;

[0031] Explanation of markings in the figure: 1. Crude gas source; 2. Extraction tower; 3. Analysis tower; 4. Tower kettle heater; 5. Alkali washing tower; 6. Condenser; 7. Ethanol absorption tower; 8. Adsorption tower; 9. Product collection bottle; 10. Refrigerant storage tank; 11. Extractant recovery tank; 12. Extractant tank. DETAILED DESCRIPTION

[0032] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of the present invention are described in detail below in combination with the preferred embodiments.

[0033] Device Embodiment

[0034] like Figure 1 As shown, it is a schematic diagram of a purification device for nitric oxide gas of the present invention; this embodiment provides a device for purifying nitric oxide gas, including an extraction tower 2, a desorption tower 3, an alkali washing tower 5, a condenser 6, an ethanol absorption tower 7 and an adsorption tower 8 connected in sequence. By sequentially arranging the extraction tower 2, the desorption tower 3, the alkali washing tower 5, the condenser 6, the ethanol absorption tower 7 and the adsorption tower 8, the device can achieve efficient purification of nitric oxide gas, and each independent processing device removes specific impurities, thereby ensuring that the final nitric oxide gas has high purity.

[0035] The extraction tower 2 is provided with an extraction tower feed port in the middle, an extraction tower discharge port at the bottom, an extractant inlet at the top, and the ratio of the diameter to the height of the extraction tower 2 is 38:4800; the extractant inlet is connected with an extractant tank 12, and the extractant is introduced into the extraction tower 2 from the extractant tank 12, and the amount of the extractant added is 1 / 4 to 1 / 3 of the volume of the extraction tower 2, the extraction tower feed port is connected with the crude gas source 1 pipeline, and the extraction tower discharge port is connected with the analytical tower 3. Through the coordination reaction of the extractant ferrous ions and nitric oxide in the extraction tower 2, efficient extraction of nitric oxide is achieved and the occurrence of disproportionation reaction is reduced.

[0036] The middle position of the analytical tower 3 is provided with an analytical tower feed port, the top position is provided with an analytical tower discharge port, the bottom of the analytical tower 3 is provided with a tower kettle heater 4, the bottom position of the analytical tower 3 is also provided with an extractant outlet, and the diameter and height ratio of the analytical tower 3 is 38:4800; the extraction tower discharge port is connected with the analytical tower feed port pipeline, the analytical tower 3 extractant outlet is connected with the extractant recovery tank 11, and the analytical tower discharge port is connected with the alkali washing tower 5. By recycling and reusing the extractant in the analytical tower 3, the waste of the extractant is reduced while ensuring the extraction effect.

[0037] The alkali washing tower 5 is provided with an alkali washing tower feed port at the bottom and an alkali washing tower discharge port at the top. The diameter and height ratio of the alkali washing tower 5 is 1:30. The alkali washing tower 5 is filled with a sodium hydroxide solution with a mass concentration of 5%. The amount of the sodium hydroxide solution added is 1 / 3 to 2 / 3 of the volume of the alkali washing tower 5. The alkali washing tower discharge port is connected with a condenser 6. The alkali washing tower 5 is filled with a sodium hydroxide solution with a suitable concentration and volume, which can effectively remove the acidic impurities nitrogen dioxide and carbon dioxide without causing resource waste and environmental problems.

[0038] The condenser 6 is provided with a condenser feed port at one end and a condenser discharge port at the other end, the discharge port of the alkali washing tower is connected to the condenser feed port pipeline, the condenser 6 is also provided with a refrigerant inlet and a refrigerant outlet, the refrigerant inlet and the refrigerant outlet are respectively connected to the refrigerant storage tank 10, and the condenser discharge port is connected to the ethanol absorption tower 7. The refrigerant circulating in the condenser 6 can effectively cool the gas to a suitable temperature and remove moisture.

[0039] The ethanol absorption tower 7 is provided with an ethanol absorption tower feed port at the bottom end, and an ethanol absorption tower discharge port at the top end. The diameter and height ratio of the ethanol absorption tower 7 is 1:30. The ethanol absorption tower 7 is filled with anhydrous ethanol, and the amount of anhydrous ethanol added is 1 / 3 to 2 / 3 of the volume of the ethanol absorption tower 7. The condenser discharge port is connected to the ethanol absorption tower feed port pipeline, and the ethanol absorption tower discharge port is connected to the adsorption tower 8. The anhydrous ethanol filled in the ethanol absorption tower 7 can selectively absorb the nitrous oxide impurities that are difficult to remove in the gas.

[0040] The adsorption tower 8 has an adsorption tower feed port at the bottom, an adsorption tower discharge port at the top, a diameter-to-height ratio of the adsorption tower 8 of 45:1000, a 13X molecular sieve filled inside the adsorption tower 8, an ethanol absorption tower discharge port connected to the adsorption tower feed port pipeline, and an adsorption tower discharge port connected to a product collection bottle 9 pipeline. The 13X molecular sieve can further deeply remove nitrous oxide and moisture, ensuring that the final nitric oxide gas meets the high purity requirements.

[0041] A first valve is provided on the connecting pipe between the crude gas source 1 and the extraction tower 2, a second valve is provided on the connecting pipe between the extraction tower 2 and the analysis tower 3, a third valve is provided on the connecting pipe between the analysis tower 3 and the alkali washing tower 5, a fourth valve is provided on the connecting pipe between the alkali washing tower 5 and the condenser 6, a fifth valve is provided on the connecting pipe between the condenser 6 and the ethanol absorption tower 7, a sixth valve is provided on the connecting pipe between the ethanol absorption tower 7 and the adsorption tower 8, and a seventh valve is provided on the connecting pipe between the adsorption tower 8 and the product collecting bottle 9.

[0042] The implementation principle of this embodiment is that the crude nitric oxide gas is introduced into the extraction tower 2, and the extractant is introduced at the same time. The extractant reacts with the nitric oxide to remove most of the impurities. The extracted phase is introduced into the analysis tower 3, and the nitric oxide gas is analyzed again by heating. Then, it is introduced into the alkali washing tower 5 to remove the acidic impurities of nitrogen dioxide and carbon dioxide, and then introduced into the condenser 6 to remove moisture. Finally, it is introduced into the ethanol absorption tower 7 and the adsorption tower 8. The anhydrous ethanol inside the ethanol absorption tower 7 can selectively absorb the nitrous oxide impurities that are difficult to remove in the gas, and the 13X molecular sieve in the adsorption tower 8 can further deeply remove nitrous oxide and moisture, so as to finally obtain high-purity nitric oxide gas.

[0043] Method Example 1

[0044] This embodiment provides a method for purifying nitric oxide gas, which is implemented using a device for purifying nitric oxide gas in the device embodiment, and includes the following steps:

[0045] The crude nitric oxide gas with a purity of 99% is introduced into the extraction tower 2 at a flow rate of 8 L / min, and the extractant is transported from the extractant inlet at the upper end of the extraction tower 2. The extractant is a 1 mol / L ferrous sulfate solution. The extraction phase obtained after the extraction is completed is introduced into the analysis tower 3 for heating and analysis. The temperature is raised to 110°C during analysis. At the same time, the analyzed extractant is discharged from the extractant outlet at the bottom of the analysis tower 3 to recover the extractant.

[0046] The analyzed gas is passed into the alkali washing tower 5, which is filled with a sodium hydroxide solution with a mass concentration of 5%. After the gas is washed with alkali to remove nitrogen dioxide and carbon dioxide impurities, it is passed into the condenser 6 for condensation and water removal. The refrigerant in the condenser 6 is dichloromethane, and the refrigerant temperature is -30°C.

[0047] After passing through the condenser 6, the gas is passed into the ethanol absorption tower 7, in which the nitrous oxide impurities in the gas are absorbed by anhydrous ethanol. The gas after ethanol absorption is passed into the adsorption tower 8 filled with 13X molecular sieve, in which the nitrous oxide and moisture are further deeply removed by the 13X molecular sieve. The gas after adsorption is collected in the product collection bottle 9 to obtain a nitric oxide product with a purity of 99.991%.

[0048] Method Example 2

[0049] This embodiment provides a method for purifying nitric oxide gas, which is implemented using a device for purifying nitric oxide gas in the device embodiment, and includes the following steps:

[0050] The crude nitric oxide gas with a purity of 99% is introduced into the extraction tower 2 at a flow rate of 8 L / min, and the extractant is transported from the extractant inlet at the upper end of the extraction tower 2. The extractant is a 1.2 mol / L ferrous sulfate solution. The extraction phase obtained after the extraction is completed is introduced into the analysis tower 3 for heating and analysis. The temperature is raised to 120°C during analysis. At the same time, the analyzed extractant is discharged from the extractant outlet at the bottom of the analysis tower 3 to recover the extractant.

[0051] The analyzed gas is passed into the alkali washing tower 5, which is filled with a sodium hydroxide solution with a mass concentration of 5%. After the gas is washed with alkali to remove nitrogen dioxide and carbon dioxide impurities, it is passed into the condenser 6 for condensation and water removal. The refrigerant in the condenser 6 is dichloromethane, and the refrigerant temperature is -30°C.

[0052] After passing through the condenser 6, the gas is passed into the ethanol absorption tower 7, in which the nitrous oxide impurities in the gas are absorbed by anhydrous ethanol. The gas after the ethanol absorption is passed into the adsorption tower 8 filled with 13X molecular sieve, in which the nitrous oxide and moisture are further deeply removed by the 13X molecular sieve. The gas after the adsorption is collected in the product collection bottle 9 to obtain a nitric oxide product with a purity of 99.994%.

[0053] Method Example 3

[0054] This embodiment provides a method for purifying nitric oxide gas, which is implemented using a device for purifying nitric oxide gas in the device embodiment, and includes the following steps:

[0055] The crude nitric oxide gas with a purity of 99% is introduced into the extraction tower 2 at a flow rate of 10L / min, and the extractant is transported from the extractant inlet at the upper end of the extraction tower 2. The extractant is a 1.3mol / L ferrous sulfate solution. The extraction phase obtained after the extraction is completed is introduced into the analysis tower 3 for heating and analysis. The temperature is raised to 100°C during the analysis. At the same time, the analyzed extractant is discharged from the extractant outlet at the bottom of the analysis tower 3 to recover the extractant.

[0056] The analyzed gas is passed into the alkali washing tower 5, which is filled with a sodium hydroxide solution with a mass concentration of 5%. After the gas is washed with alkali to remove nitrogen dioxide and carbon dioxide impurities, it is passed into the condenser 6 for condensation and water removal. The refrigerant in the condenser 6 is dichloromethane, and the refrigerant temperature is -30°C.

[0057] After passing through the condenser 6, the gas is passed into the ethanol absorption tower 7, in which the nitrous oxide impurities in the gas are absorbed by anhydrous ethanol. The gas after the ethanol absorption is passed into the adsorption tower 8 filled with 13X molecular sieve, in which the nitrous oxide and moisture are further deeply removed by the 13X molecular sieve. The gas after the adsorption is collected in the product collection bottle 9 to obtain a nitric oxide product with a purity of 99.992%.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A device for purifying nitric oxide gas, characterized in that: It includes an extraction tower, a decomposition tower, an alkali washing tower, a condenser, an ethanol absorption tower and an adsorption tower which are connected in sequence; The extraction tower is provided with an extraction tower feed port in the middle, and an extraction tower discharge port at the bottom; The middle position of the analytical tower is provided with an analytical tower feed port, and the top position is provided with an analytical tower discharge port; The bottom of the alkali washing tower is provided with an alkali washing tower feed port, and the top of the alkali washing tower is provided with an alkali washing tower discharge port; The condenser is provided with a condenser feed port at one end and a condenser discharge port at the other end; The bottom of the ethanol absorption tower is provided with an ethanol absorption tower feed port, and the top of the ethanol absorption tower is provided with an ethanol absorption tower discharge port; The adsorption tower bottom is provided with an adsorption tower feed port, and the adsorption tower top is provided with an adsorption tower discharge port; The extraction tower feed port is connected to the crude gas source pipeline, the extraction tower discharge port is connected to the analysis tower feed port pipeline, the analysis tower discharge port is connected to the alkali washing tower feed port pipeline, the alkali washing tower discharge port is connected to the condenser feed port pipeline, the condenser discharge port is connected to the ethanol absorption tower feed port pipeline, the ethanol absorption tower discharge port is connected to the adsorption tower feed port pipeline, and the adsorption tower discharge port is connected to the product collection unit pipeline.

2. The device for purifying nitric oxide gas according to claim 1, characterized in that: The ratio of the diameter to the height of the extraction tower is 38:4800. An extractant inlet is also provided at the top of the extraction tower. The extractant inlet is connected to the extractant tank. The amount of extractant added is 1 / 4 to 1 / 3 of the volume of the extraction tower.

3. The device for purifying nitric oxide gas according to claim 1, characterized in that: The ratio of the diameter to the height of the analytical tower is 38:4800. A kettle heater is provided at the bottom of the analytical tower. An extractant outlet is also provided at the bottom of the analytical tower. The extractant outlet of the analytical tower is connected to an extractant recovery tank.

4. The device for purifying nitric oxide gas according to claim 1, characterized in that: The ratio of the diameter to the height of the alkali washing tower is 1:

30. The interior of the alkali washing tower is filled with a sodium hydroxide solution, and the amount of the sodium hydroxide solution added is 1 / 3 to 2 / 3 of the volume of the alkali washing tower.

5. The device for purifying nitric oxide gas according to claim 1, characterized in that: The condenser is also provided with a refrigerant inlet and a refrigerant outlet, and the refrigerant inlet and the refrigerant outlet are respectively connected to the refrigerant storage tank.

6. The device for purifying nitric oxide gas according to claim 1, characterized in that: The diameter and height ratio of the ethanol absorption tower is 1:30, and the interior of the ethanol absorption tower is filled with anhydrous ethanol, and the added amount of anhydrous ethanol is 1 / 3 to 2 / 3 of the volume of the ethanol absorption tower. The diameter and height ratio of the adsorption tower is 45:1000, and the interior of the adsorption tower is filled with 13X molecular sieve.

7. The device for purifying nitric oxide gas according to claim 1, characterized in that: A first valve is provided on the connecting pipe between the crude gas source and the extraction tower, a second valve is provided on the connecting pipe between the extraction tower and the analysis tower, a third valve is provided on the connecting pipe between the analysis tower and the alkali washing tower, a fourth valve is provided on the connecting pipe between the alkali washing tower and the condenser, a fifth valve is provided on the connecting pipe between the condenser and the ethanol absorption tower, a sixth valve is provided on the connecting pipe between the ethanol absorption tower and the adsorption tower, and a seventh valve is provided on the connecting pipe between the adsorption tower and the product collection unit.

8. A method for purifying nitric oxide gas, using a device for purifying nitric oxide gas according to any one of claims 1 to 6, characterized in that: The steps include: The crude nitric oxide gas is introduced into an extraction tower, and an extractant is delivered from an extractant inlet at the upper end of the extraction tower. The extraction phase obtained after the extraction is completed is introduced into a decomposition tower for heating and decomposition, and the extractant is recovered from an extractant outlet at the bottom of the decomposition tower; the decomposed nitric oxide gas is introduced into an ethanol absorption tower after passing through an alkali washing tower and a condenser; the gas absorbed by ethanol in the ethanol absorption tower is introduced into an adsorption tower filled with 13X molecular sieve; the gas after adsorption is collected in a product collection bottle to obtain a nitric oxide product with a purity greater than 99.99%.

9. A method for purifying nitric oxide gas according to claim 8, characterized in that: The flow rate of crude nitric oxide gas entering the extraction tower is 5-10 L / min, and the extractant in the extraction tower is ferrous sulfate solution, and the concentration of the ferrous sulfate solution is 1-1.3 mol / L.

10. A method for purifying nitric oxide gas according to claim 8, characterized in that: The temperature of the extraction phase is raised to 100-120°C when being analyzed in the analysis tower; the interior of the alkali washing tower is filled with a sodium hydroxide solution with a mass concentration of 5%; the refrigerant in the condenser is dichloromethane, and the refrigerant temperature is -30°C.

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