System for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon through air separation

Abstract

The utility model provides a system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon through air separation, relates to the technical field of air separation, and solves the technical problems that an existing liquid argon rectification device is low in heat exchange efficiency and poor in liquid argon backflow purification effect. The device comprises a lower tower for carrying out primary rectification and an upper tower for carrying out secondary rectification, the middle part of the upper tower is communicated with a crude argon tower for carrying out rectification on argon fraction gas, and the crude argon tower is communicated with a pure argon tower for carrying out rectification on crude argon gas; the pure argon tower is provided with a pure argon evaporator for heating crude argon; the pure argon evaporator is communicated with a crude argon condenser at the top of the crude argon tower and a pure argon condenser at the top of the pure argon tower and is used for recycling a condensed medium as a heating heat source. According to the device disclosed by the utility model, ultrapure nitrogen, oxygen and argon can be produced; and the condensed medium can be recycled as a heating heat source, so that the energy efficiency of the system and the reflux efficiency of argon are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of air separation, and more specifically, to a system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation. Background Art

[0002] Air separation technology is a common method for industrially preparing high-purity gases (such as ultra-pure nitrogen and ultra-pure oxygen). This technology mainly separates based on the different boiling points of the components in air. The basic principle of air separation is to use the cryogenic distillation method, that is, after liquefying air, it is separated in a distillation column according to the boiling point differences of the gas components. The boiling point of nitrogen is -195.8°C, while the boiling point of oxygen is -183°C, so the separation of the two can be achieved by adjusting the distillation temperature.

[0003] First, air needs to be purified to remove moisture, carbon dioxide and other impurities, and then it is liquefied by compression and cooling. In this process, equipment such as expanders and heat exchangers are usually used to lower the temperature of air and increase its pressure. The liquefied air is introduced into the distillation column. There are multiple trays or packings set at different heights in the column. As the liquid rises in the column and the vapor descends, components with different boiling points are gradually separated. High-purity nitrogen is obtained at the top of the column, while relatively pure oxygen is collected at the bottom of the column. To obtain higher-purity nitrogen or oxygen, further purification steps are required. For example, an adsorbent bed can be used to remove residual moisture and other impurities, or membrane separation technology can be used to further improve the purity.

[0004] Argon is a noble gas with very stable chemical properties and is not easily chemically reacted with other elements. Therefore, it has important applications as a protective gas in the industrial field. The content of argon in the atmosphere accounts for about 0.9%, which is the third largest component in air, after nitrogen and oxygen. Compared with nitrogen and oxygen, its content is less, and the boiling point of argon is between that of nitrogen and oxygen (the boiling point of argon is -185.87°C), which makes the extraction of argon a challenging task.

[0005] For example, a high-efficiency liquid argon distillation device proposed in the patent with the publication number CN221527069U includes a crude argon distillation column. A first condenser is installed at the upper end of the crude argon distillation column. A crude argon gas filtration mechanism is installed inside the crude argon distillation column. A first delivery pipe is installed at the lower end of the first condenser. A reflux pipe is installed on the side of the crude argon distillation column. The other end of the first delivery pipe is installed with a refined argon distillation column. This device can obtain liquid argon with relatively high purity through multiple distillations. However, for the crude argon distillation column and the refined argon distillation column of this device, only condensers are set, and the heating of liquid argon depends on the ambient temperature, resulting in low heat exchange efficiency and weak liquid argon reflux purification effect. Summary of the Utility Model

[0006] The purpose of the present utility model is to provide a system for air separation to prepare ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon, so as to solve the technical problems of low heat exchange efficiency of the existing liquid argon rectification device and weak purification effect of liquid argon reflux.

[0007] The embodiments of the present utility model are realized through the following technical solutions:

[0008] A system for air separation to prepare ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon, including a lower column for the first rectification and an upper column for the second rectification. The middle part of the upper column is connected to a crude argon column for rectifying argon fraction gas. The crude argon column is connected to a fine argon column for rectifying crude argon gas. The fine argon column is provided with a pure argon evaporator for heating the crude argon gas. The pure argon evaporator is connected to the crude argon condenser at the top of the crude argon column and the pure argon condenser at the top of the fine argon column to reuse the condensed medium as a heating heat source.

[0009] Preferably, the bottom of the lower column is connected to the crude argon condenser and the pure argon condenser to transport part of the oxygen-rich liquid air as a cold source.

[0010] Preferably, the top of the crude argon column is connected to the bottom of the fine argon column, and the bottom of the fine argon column is also provided with a drain port for discharging pure argon.

[0011] Preferably, the fine argon column is also provided with a reflux pipeline for refluxing pure argon.

[0012] Preferably, it further includes an air filtration system, an air compression system, an air precooling system, an air purification system and an air rectification system. The air rectification system includes the lower column and the upper column.

[0013] Preferably, the air filtration system includes several stages of air filters for filtering dust and mechanical impurities; the air compression system includes a centrifugal air compressor for compressing air to 0.57 Mpa.

[0014] Preferably, the air precooling system includes an air cooling tower for cooling the high-temperature compressed air and a circulating cooling water system for supplying cold to the air cooling tower. The circulating cooling water system includes a cooling water filter for filtering cooling water and a cooling water pump for supplying cooling water.

[0015] Preferably, the air purification system includes a first adsorber and a second adsorber for adsorbing and removing moisture and carbon dioxide. The first adsorber and the second adsorber are also respectively provided with a first heater and a second heater for regenerating them.

[0016] Preferably, the cold energy of the device is mainly provided by two turbo-expander systems. The nitrogen reheated by the main heat exchanger is combined with the nitrogen supplemented by the nitrogen feeder and then enters the circulating nitrogen compressor for boosting. After boosting, it is divided into two parts: one part directly enters the main heat exchanger, is cooled to about -7°C in the main heat exchanger, and then is extracted and sent to the expansion end of the thermal expander for expansion refrigeration, and the expanded gas returns to the main heat exchanger for reheating and then returns to the inlet of the circulating nitrogen compressor; the other part first enters the boosting ends of the thermal and cold turbo-expanders in series for boosting, then enters the main heat exchanger, a small part is liquefied and extracted from the cold end of the main heat exchanger and sent to the lower column to participate in rectification, and the rest is cooled to about -95°C in the main heat exchanger and then extracted and sent to the expansion end of the cold expander for expansion refrigeration, and the expanded gas returns to the main heat exchanger for reheating and then returns to the inlet of the circulating nitrogen compressor.

[0017] With this technical solution, through two rectification processes (lower column and upper column), as well as the crude argon column and the fine argon column dedicated to rectifying the argon fraction gas, the system can produce ultra-pure grade nitrogen, oxygen and argon gas. The design of the pure argon evaporator, the crude argon condenser and the pure argon condenser enables the condensed medium to be reused as a heating heat source, improving the energy efficiency of the system. The bottom of the lower column is connected to the crude argon condenser and the pure argon condenser, using the oxygen-rich liquid air as a cold source, optimizing the temperature control and energy utilization of the system. The top of the crude argon column is connected to the bottom of the fine argon column, and the fine argon column is provided with a reflux pipeline, which helps to maintain the continuous production process and the circulation balance of the materials. Including an air filtration system, an air compression system, an air precooling system and an air purification system, which ensures the air quality entering the rectification system, thereby improving the purity of the final product. By improving the product purity and energy recycling, the system helps to reduce the production cost and improve the economic benefit. The design of the system reduces energy consumption and waste emissions, meets the environmental protection requirements and is friendly to the environment.

[0018] The technical solution of the embodiment of the present utility model has at least the following advantages and beneficial effects:

[0019] 1. The system of the present utility model can produce ultra-pure grade nitrogen, oxygen and argon gas;

[0020] 2. The condensed medium of the present utility model can be reused as a heating heat source, improving the energy efficiency of the system and the reflux efficiency of argon gas;

[0021] 3. The present utility model reduces the production cost and improves the economic benefit. The design of the system reduces energy consumption and waste emissions, meets the environmental protection requirements and is friendly to the environment. Description of the Drawings

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a schematic diagram of the overall structure of a system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation provided in Embodiment 1 of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the crude argon tower and the fine argon tower of a system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation provided in Embodiment 2 of the present invention;

[0025] Figure 3 It is a schematic diagram of the structure of the air rectification system of a system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation provided in Embodiment 2 of the present invention;

[0026] Reference numerals: 1, air filtration system; 2, air compression system; 3, air precooling system; 4, air purification system; 5, air rectification system; 61, crude argon tower; 62, fine argon tower; 63, pure argon evaporator; 64, crude argon condenser; 65, pure argon condenser; 31, air cooling tower; 32, cooling water pump; 33, cooling water filter; 411, first adsorber; 412, second adsorber; 421, first heater; 422, second heater; 51, lower column; 52, upper column. Detailed embodiments

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0029] It should be noted that like reference numerals and letters denote like items in the following figures. Therefore, once an item is defined in one figure, it is not necessary to further define and explain it in subsequent figures.

[0030] In the description of the present utility model, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0031] In the description of the present utility model, it should also be noted that unless otherwise clearly specified and defined, if terms such as "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0032] Embodiment 1

[0033] A system for air separation to prepare ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon, including a lower column 51 for the first rectification and an upper column 52 for the second rectification. The middle part of the upper column 52 is connected to a crude argon column 61 for rectifying argon fraction gas. The crude argon column 61 is connected to a pure argon column 62 for rectifying crude argon gas. The pure argon column 62 is provided with a pure argon evaporator 63 for heating the crude argon gas. The pure argon evaporator 63 is connected to a crude argon condenser 64 at the top of the crude argon column 61 and a pure argon condenser 65 at the top of the pure argon column 62 to recycle the condensed medium as a heating heat source.

[0034] In this embodiment, it further includes an air filtration system 1, an air compression system 2, an air precooling system 3, an air purification system 4 and an air rectification system 5. The air rectification system 5 includes the lower column 51 and the upper column 52.

[0035] In this embodiment, the air filtration system 1 includes air filters of several stages for filtering dust and mechanical impurities; the air compression system 2 includes a centrifugal air compressor for compressing air to 0.57 Mpa.

[0036] In this embodiment, the air pre-cooling system 3 includes an air-cooling tower 31 for cooling the high-temperature compressed air and a circulating cooling water system for supplying cooling to the air-cooling tower 31. The circulating cooling water system includes a cooling water filter 33 for filtering the cooling water and a cooling water pump 32 for supplying the cooling water.

[0037] In this embodiment, the air purification system 4 includes a first adsorber 411 and a second adsorber 412 for adsorbing and removing moisture and carbon dioxide. The first adsorber 411 and the second adsorber 412 are also respectively provided with a first heater 421 and a second heater 422 for regenerating them.

[0038] Working principle and usage method:

[0039] Through two rectification processes (lower column 51 and upper column 52), as well as a crude argon column 61 and a pure argon column 62 specifically for rectifying the argon fraction gas, the system can produce ultra-pure nitrogen, oxygen, and argon gas. The design of the pure argon evaporator 63, the crude argon condenser 64, and the pure argon condenser 65 enables the condensed medium to be reused as a heating heat source, improving the energy efficiency of the system. The bottom of the lower column 51 is connected to the crude argon condenser 64 and the pure argon condenser 65, using the oxygen-rich liquid air as a cold source, optimizing the temperature control and energy utilization of the system. The top of the crude argon column 61 is connected to the bottom of the pure argon column 62, and the pure argon column 62 is provided with a reflux pipeline, which helps to maintain the continuous production process and the circulation balance of materials. The air filtration system 1, the air compression system 2, the air pre-cooling system 3, and the air purification system 4 ensure the air quality entering the rectification system, thereby improving the purity of the final product.

[0040] Embodiment 2

[0041] The difference between this embodiment and Embodiment 1 is only that, in this embodiment, the bottom of the lower column 51 is connected to the crude argon condenser 64 and the pure argon condenser 65 to transport part of the oxygen-rich liquid air as a cold source.

[0042] In this embodiment, the top of the crude argon column 61 is connected to the bottom of the pure argon column 62, and the bottom of the pure argon column 62 is also provided with a drain port for discharging pure argon.

[0043] In this embodiment, the pure argon column 62 is also provided with a reflux pipeline for refluxing pure argon.

[0044] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation, comprising a lower column (51) for performing the first rectification and an upper column (52) for performing the second rectification, characterized in that: The middle part of the upper column (52) is connected to a crude argon column (61) for rectifying argon fraction gas. The crude argon column (61) is connected to a pure argon column (62) for rectifying crude argon gas. The pure argon column (62) is provided with a pure argon evaporator (63) for heating the crude argon gas. The pure argon evaporator (63) is connected to a crude argon condenser (64) at the top of the crude argon column (61) and a pure argon condenser (65) at the top of the pure argon column (62) to recycle the condensed medium as a heating heat source.

2. The system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation according to claim 1, wherein: The bottom of the lower column (51) is connected to the crude argon condenser (64) and the pure argon condenser (65) to transport a part of oxygen-rich liquid air as a cold source.

3. A system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation according to claim 1 or 2, characterized in that: The top of the crude argon column (61) is connected to the bottom of the pure argon column (62), and a drain port for discharging pure argon is also provided at the bottom of the pure argon column (62).

4. A system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation according to claim 1 or 2, characterized in that: The pure argon column (62) is also provided with a reflux pipeline for refluxing pure argon.

5. A system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation according to claim 1 or 2, characterized in that: It further includes an air filtration system (1), an air compression system (2), an air precooling system (3), an air purification system (4) and an air rectification system (5). The air rectification system (5) includes the lower column (51) and the upper column (52).

6. The system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation according to claim 5, wherein: The air filtration system (1) includes air filters of several stages for filtering dust and mechanical impurities; the air compression system (2) includes a centrifugal air compressor for compressing air to 0.57 Mpa.

7. The system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation according to claim 5, characterized in that: The air precooling system (3) includes an air cooling tower (31) for cooling the high-temperature compressed air and a circulating cooling water system for supplying cooling to the air cooling tower (31). The circulating cooling water system includes a cooling water filter (33) for filtering cooling water and a cooling water pump (32) for supplying cooling water.

8. The system for preparing ultra-pure nitrogen, ultra-pure oxygen and ultra-pure argon by air separation according to claim 5, wherein: The air purification system (4) includes a first adsorber (411) and a second adsorber (412) for adsorbing and removing moisture and carbon dioxide. The first adsorber (411) and the second adsorber (412) are also respectively provided with a first heater (421) and a second heater (422) for regenerating them.

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