A distillation system for an air separation unit

Abstract

This utility model discloses a distillation system for an air separation unit, including a crude argon column, a crude argon condenser, a pure argon column, a pure argon condenser, a pure argon evaporator, a liquid argon storage tank, a circulating pump, a lower column, an upper column, and a main condenser-evaporator. This utility model achieves efficient purification of argon components through the synergistic two-stage distillation of the crude argon column and the pure argon column: the shell of the crude argon column preferentially removes oxygen components from the argon fraction, while the shell of the pure argon column further distills and removes nitrogen, achieving the extraction of high-purity liquid argon products. The system uses oxygen-enriched liquid air as a cold source to provide cooling for the crude argon condenser and the pure argon condenser. At the same time, rising steam is generated through vaporization in the pure argon evaporator, forming an energy closed loop, achieving material recycling and reducing the energy consumption of the raw material gas.

Description

Technical Field

[0001] This utility model relates to the field of air separation equipment technology, specifically to a distillation system for an air separation equipment. Background Technology

[0002] Air separation engineering, simply put, is the process of separating gases such as oxygen, nitrogen, and argon from the air with high purity using a large-scale air separation system. The resulting gaseous products are pure oxygen and pure nitrogen.

[0003] Currently, the main process of air separation is as follows: Compressed air from the air compressor is passed through a molecular sieve to remove impurities such as moisture, carbon dioxide, and hydrocarbons. Part of the air is directly sent to the upper column of the distillation column, while the other part enters the expander, is expanded and cooled, and then sent to the lower column. In the distillation column, the rising vapor and falling liquid exchange heat, and high-purity nitrogen can be obtained at the top of the upper column, while high-purity oxygen can be obtained at the bottom of the upper column.

[0004] Argon, as an important byproduct of air separation units, is widely used in industries with extremely high requirements for gas purity, such as semiconductors, welding, and medical applications. Currently, traditional argon purification processes mainly rely on single-tower distillation or chemical adsorption methods. Traditional processes suffer from problems such as residual oxygen and nitrogen, low equipment efficiency, and fluctuations in product purity.

[0005] To address this, a distillation system for an air separation unit is proposed to perform staged distillation and closed-loop reflux operations, thereby improving argon extraction quality and reducing process energy consumption. Utility Model Content

[0006] The purpose of this invention is to provide a distillation system for an air separation unit to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a distillation system for an air separation unit, comprising a crude argon column, a crude argon condenser, a pure argon column, a pure argon condenser, a pure argon evaporator, a liquid argon storage tank, a circulating pump, a lower column, an upper column, and a main condenser-evaporator. The crude argon column is equipped with a crude argon condenser at its upper end, which is connected to one end of the middle of the pure argon column via a branch. The pure argon column is equipped with a pure argon condenser at its top, and the bottom of the pure argon column is connected to the pure argon evaporator via a branch. Another branch at the bottom of the pure argon column is connected to the liquid argon storage tank. The bottom of the crude argon column is connected to a circulating pump, which is connected to the upper column via a branch. The bottom of the upper column is connected to the lower column, and a main condenser-evaporator is installed between the upper and lower columns.

[0008] Preferably, the feed gas for the crude argon tower is the argon fraction extracted from the lower part of the upper tower, and the argon fraction is removed by low-temperature distillation inside the crude argon tower.

[0009] Preferably, both the crude argon tower and the pure argon tower are connected to oxygen-enriched pipelines for the lower tower.

[0010] Preferably, the reflux liquid at the bottom of the crude argon column is circulated into the upper column via a circulating pump.

[0011] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model achieves efficient purification of argon components through the synergistic two-stage distillation of crude argon tower and pure argon tower: the shell of the crude argon tower preferentially removes oxygen components from the argon fraction, while the shell of the pure argon tower further distills and removes nitrogen, thereby achieving the extraction of high-purity liquid argon products. The system uses oxygen-enriched liquid air as a cold source to provide cooling for the crude argon condenser and the pure argon condenser. At the same time, rising steam is generated through vaporization in the pure argon evaporator, forming an energy closed loop, achieving material recycling and reducing the energy consumption of raw material gas. 2. This utility model avoids single-tower overload through a dual-tower division of labor design, thereby reducing energy consumption while improving the extraction rate of liquid argon products. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the process flow of this utility model.

[0013] In the diagram: Crude argon tower-1, Crude argon condenser-2, Pure argon tower-3, Pure argon condenser-4, Pure argon evaporator-5, Liquid argon storage tank-6, Circulating pump-7, Lower tower-8, Upper tower-9, Main condenser-evaporator-10. Detailed Implementation

[0014] To further explain the technical solution of this utility model, a detailed description is provided below through specific embodiments.

[0015] Please see Figure 1 This utility model provides a distillation system for an air separation unit, including a crude argon column 1, a crude argon condenser 2, a pure argon column 3, a pure argon condenser 4, a pure argon evaporator 5, a liquid argon storage tank 6, a circulating pump 7, a lower column 8, an upper column 9, and a main condenser-evaporator 10. The crude argon column 1 is equipped with a crude argon condenser 2 at its upper end. The crude argon condenser 2 is connected to one end of the middle of the pure argon column 3 via a branch. The pure argon column 3 is equipped with a pure argon condenser 4 at its top. The bottom of the pure argon column 3 is connected to the pure argon evaporator 5 via a branch. Another branch at the bottom of the pure argon column 3 is connected to the liquid argon storage tank 6. The bottom of the crude argon column 1 is connected to the circulating pump 7, which is connected to the upper column 9 via a branch. The bottom of the upper column 9 is connected to the lower column 8. The main condenser-evaporator 10 is installed between the upper column 9 and the lower column 8.

[0016] Among them, crude argon column 1 is used to separate oxygen and argon components in argon fraction, and to increase the argon concentration to crude argon gas through rectification, while controlling the N2 content in argon fraction to avoid disrupting the rectification process; Crude Argon Condenser 2: It uses liquid air as a cold source to condense the oxygen component in crude argon gas, while evaporating part of the liquid air to form a circulating flow. The temperature difference and liquid level affect its heat load. Its structure is similar to the main condenser evaporator, but the medium is liquid air and crude argon gas. Pure Argon Tower 3: Further distills and purifies crude argon gas, separating residual oxygen and nitrogen through a packed structure to produce high-purity argon gas; Pure argon condenser 4: condenses the argon gas at the top of the pure argon tower 3 to form reflux liquid to maintain the distillation process. Its structure is similar to that of the crude argon condenser 2, but the medium is pure argon. Pure argon evaporator 5: heats the liquid argon at the bottom of the pure argon tower 3, providing the heat required for distillation, and usually forms a thermally coupled system with the pure argon condenser 4; Liquid argon storage tank 6: Stores the liquid argon product after distillation, serving as an intermediate buffer or export container; Lower column 8: Preliminary distillation and separation: After the rising gas comes into contact with the reflux liquid for mass transfer, pure nitrogen is obtained at the top and oxygen-enriched liquid air is obtained at the bottom; Diversion function: lean liquid air is extracted from the middle section, liquid sludge nitrogen is extracted from the upper middle section and sent to the upper column 9, and nitrogen at the top is diverted to the main condenser evaporator 10, liquid nitrogen pump and reflux system; Upper column 9: Deep distillation: Receives oxygen-enriched liquid air, lean liquid air and liquid nitrogen from lower column 8, produces liquid oxygen in the middle, produces nitrogen at the top, and extracts argon fraction from the middle and lower sections to crude argon column 1; Main condenser-evaporator 10: The core heat exchange equipment, which condenses the nitrogen in the lower tower 8 to form liquid nitrogen, and at the same time, vaporizes the liquid oxygen in the main condenser.

[0017] The raw material gas for crude argon tower 1 is the argon fraction extracted from the lower part of upper tower 9. The argon fraction is removed by low-temperature distillation inside crude argon tower 1. That is, through low-temperature distillation of crude argon tower 1, argon gas can be effectively separated from other components, thereby improving the argon extraction rate.

[0018] Both the crude argon tower 1 and the pure argon tower 3 are connected to the oxygen-enriched pipe of the lower tower 8 at their tops. This design maintains the distillation heat balance of the crude argon tower 1 and the pure argon tower 3 by introducing oxygen-enriched gas from the lower tower 8 as a cold source.

[0019] The reflux liquid at the bottom of the crude argon column 1 is circulated into the upper column 9 via the circulation pump 7. The circulation pump 7 re-inputs the reflux liquid at the bottom of the crude argon column 1 into the upper column 9, which can replenish the reflux liquid volume of the upper column 9 and stabilize the distillation conditions.

[0020] The working principle is as follows: First, the argon fraction extracted from the lower part of the upper column 9 is used as the feed gas for the crude argon column 1. The argon fraction enters from the bottom of the crude argon column 1 and undergoes low-temperature distillation to remove the oxygen component from the argon fraction. At the top of the crude argon column 1, oxygen-free crude argon gas is obtained. The crude argon gas enters the crude argon condenser 2 at the top of the column and exchanges heat with the oxygen-enriched liquid air from the lower column 8. Most of the crude argon is condensed and used as reflux liquid to maintain the distillation of the crude argon column 1. The argon fraction reflux liquid at the bottom of the crude argon column 1 is transported by the circulating pump 7 and returned to the interior of the upper column 9 to participate in the distillation activities of the upper column 9. A portion of the non-condensable, oxygen-free crude argon gas drawn from the crude argon condenser 2 will be sent to the middle of the pure argon tower 3. In the pure argon tower 3, the remaining nitrogen components will be removed by low-temperature distillation, thereby improving the distillation efficiency. The gas entering the top of the pure argon tower 3 will be liquefied by the oxygen-enriched liquid air from the lower tower 8 in the pure argon condenser 4 to form the pure argon tower 3 distillation reflux liquid. The non-condensable waste gas at the top of the pure argon tower 3 will be directly vented. The liquid argon at the bottom of the pure argon tower 3 will be sent to the pure argon evaporator 5 to vaporize with the oxygen-enriched liquid air from the lower tower 8, providing rising steam for the distillation of the pure argon tower 3. Finally, a portion of the liquid argon will be drawn from the bottom of the pure argon tower 3 and sent as product to the liquid argon storage tank 6. In this way, the dual-tower synergistic high-efficiency extraction of pure argon is achieved, and the surge in energy consumption caused by the overload of the traditional single tower is reduced.

[0021] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A rectification system of an air separation unit, characterized by: The system includes a crude argon tower (1), a crude argon condenser (2), a pure argon tower (3), a pure argon condenser (4), a pure argon evaporator (5), a liquid argon storage tank (6), a circulating pump (7), a lower tower (8), an upper tower (9), and a main condenser-evaporator (10). The crude argon tower (1) is equipped with a crude argon condenser (2) at its upper end. The crude argon condenser (2) is connected to one end of the middle of the pure argon tower (3) via a branch. The pure argon tower (3) is equipped with a pure argon condenser (4) at its top. The bottom of the pure argon tower (3) is connected to the pure argon evaporator (5) via a branch. Another branch at the bottom of the pure argon tower (3) is connected to the liquid argon storage tank (6). The bottom of the crude argon tower (1) is connected to a circulating pump (7). The circulating pump (7) is connected to the upper tower (9) via a branch. The bottom of the upper tower (9) is connected to the lower tower (8). The main condenser-evaporator (10) is installed between the upper tower (9) and the lower tower (8).

2. The rectification system of the air separation unit of claim 1, wherein: The raw gas for the crude argon tower (1) is the argon fraction extracted from the lower part of the upper tower (9), and the argon fraction is removed by low-temperature distillation inside the crude argon tower (1).

3. The rectification system of the air separation unit of claim 1, wherein: Both the crude argon tower (1) and the pure argon tower (3) are connected to the oxygen-enriched pipeline of the lower tower (8) at their tops.

4. The rectification system of the air separation unit of claim 1, wherein: The reflux liquid at the bottom of the crude argon tower (1) is circulated into the upper tower (9) via the circulating pump (7).

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