Liquid argon circulating air separation device capable of preventing nitrogen blockage

Abstract

The utility model discloses a liquid argon circulating air separation device capable of preventing nitrogen blockage, which particularly relates to the technical field of gas separation, and comprises a raw material compression system, a liquid argon circulating air separation system and a liquid argon circulating air separation system, the precooling and purifying system comprises an air cooling tower, a water cooling tower, a water chilling unit, a cooling water pump, a chilled water pump and a purifier; the low-temperature separation system comprises an expansion machine pressurization end, an expansion machine expansion end, a main heat exchanger, a subcooler, a lower tower, a main condensation evaporator, a product liquid oxygen pump, an upper tower, a circulating liquid oxygen pump, a crude argon tower, a crude argon tower condenser, a pure argon tower, a pure argon tower condenser, a circulating liquid argon pump and a pure argon evaporator. The method is realized by starting a circulating liquid argon pump. Therefore, the problem of nitrogen blockage caused by working condition fluctuation of an argon system when the load of the air separation device is changed is avoided, the operation stability of the device is improved, the liquid argon yield or the argon extraction rate can be increased, and the economic benefit is increased.

Description

Technical Field

[0001] The utility model relates to the technical field of gas separation, in particular to a liquid argon circulation air separation device which is anti-nitrogen plugging. Background Art

[0002] Nitrogen plugging refers to a phenomenon in which the crude argon column fails to function properly due to excessive nitrogen content in the argon fraction. Due to its low boiling point, the nitrogen content in the mixture of concentrated nitrogen and crude argon at the top of the crude argon column is relatively high, lowering its condensation temperature and reducing the heat transfer temperature difference between the concentrated nitrogen and oxygen-rich liquid air. This causes non-condensable nitrogen to fill the crude argon side of the condenser, significantly reducing the amount of argon condensed, or even preventing argon from condensing, causing the condenser to malfunction. The lack of reflux at the top of the crude argon column disrupts the distillation process in the crude argon column, reducing the amount of argon entering the crude argon column. As the amount of gaseous argon fraction extracted decreases, the amount of rising steam from the column increases, the reflux ratio decreases, and the oxygen purity increases, reducing the nitrogen content in the argon fraction. This in turn causes the oxygen content to exceed the specified value, further widening the temperature difference between the crude argon condenser and evaporator, increasing the amount of reflux liquid in the crude argon column, and automatically increasing the amount of fraction extracted. This reduces the amount of rising steam from the column, increases the reflux ratio, and consequently increases the nitrogen content in the argon fraction. Such repeated changes make the crude argon tower unable to work, and the liquid argon production or argon extraction rate is seriously reduced. Utility Model Content

[0003] The utility model aims to provide a liquid argon circulation air separation device with nitrogen plugging prevention, aiming to solve the nitrogen plugging problem caused by the fluctuation of the argon system working condition when the load of the air separation device changes.

[0004] In order to achieve the above-mentioned purpose, the present invention provides the following technical solution: a liquid argon circulation air separation device that prevents nitrogen plugging, comprising:

[0005] a feedstock compression system, which includes an air compressor and a booster;

[0006] Precooling and purification system, which includes air cooling tower, water cooling tower, chiller, cooling water pump, chilled water pump and purifier;

[0007] The low-temperature separation system includes an expander booster end, an expander expansion end, a main heat exchanger, a subcooler, a lower tower, a main condenser evaporator, a product liquid oxygen pump, an upper tower, a circulating liquid oxygen pump, a crude argon tower, a crude argon tower condenser, a refined argon tower, a refined argon tower condenser, a circulating liquid argon pump, and a refined argon evaporator, wherein:

[0008] The output end of the air compressor is connected to the input end of the air cooling tower, the air cooling tower is connected to the chiller and the cooling water pump, the chilled water pump is connected to the water cooling tower, and the air cooling tower is connected to the purifier;

[0009] One path of the booster is connected to the boosting end of the expander, the main heat exchanger is connected to the expansion end of the expander, and the expansion end of the expander is connected to the lower tower; the other path is connected to the main heat exchanger, and the main heat exchanger is connected to the lower tower through a throttle valve;

[0010] The two output ends of the lower tower are respectively connected to the input ends of the main heat exchanger and the refined argon evaporator;

[0011] The five pipelines of the lower tower are all connected to the subcooler and then divided into eight pipelines after passing through the cooler, of which four pipelines are respectively connected to the upper tower, the other two pipelines are respectively extended out of the cold box as liquid nitrogen product pipelines and liquid oxygen product pipelines, and the other two pipelines are respectively connected to the crude argon tower condenser and the refined argon tower condenser;

[0012] A main condenser evaporator is provided between the lower tower and the upper tower, and the main condenser evaporator is connected to the product liquid oxygen pump;

[0013] The crude argon tower is connected to a circulating liquid oxygen pump, which is connected to the upper tower. The two pipelines of the crude argon tower condenser are connected to the upper tower and the subcooler respectively. The refined argon tower is provided with a refined argon tower condenser at the top and a refined argon evaporator at the bottom. The refined argon tower condenser is connected to the upper tower and the subcooler respectively, and the circulating liquid argon pump is connected to the crude argon tower condenser.

[0014] Preferably, the boost end of the expander is connected to the boost end aftercooler, and the boost end aftercooler is connected to the main heat exchanger.

[0015] Preferably, one pipeline of the purifier is connected to the lower tower through the main heat exchanger, and the other pipeline is connected to the booster.

[0016] Preferably, the chiller is connected to a chilled water pump.

[0017] Preferably, the product liquid oxygen pump is connected to the main heat exchanger, and the two pipelines at the top of the upper tower are connected to the main heat exchanger after passing through the cooler.

[0018] Preferably, a crude argon column condenser is provided at the top of the crude argon column.

[0019] Preferably, the three pipelines of the refined argon evaporator are respectively connected to the upper tower, the lower tower and the circulating liquid argon pump.

[0020] Preferably, one pipeline of the refined argon evaporator is used as a liquid argon product pipeline to the outside of the cold box.

[0021] In the above technical solution, the utility model provides a liquid argon circulation air separation unit that is resistant to nitrogen plugging, which has the following beneficial effects: the liquid argon product at the bottom of the refined argon tower is sent to the crude argon tower condenser through a circulating liquid argon pump, ensuring that the nitrogen content in the crude argon tower condenser is within a reasonable range, avoiding nitrogen plugging, ensuring the stable operation of the air separation unit, and improving economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0023] Figure 1 This is a structural diagram provided for an embodiment of the present utility model.

[0024] Description of reference numerals:

[0025] MAC, air compressor; BAC, booster; AC, air cooling tower; EC, water cooling tower; RU, chiller; WP1, cooling water pump; WP2, chilled water pump; MS1 / MS2, purifier; ETC, expander boost end; ET, expander expansion end; MEH, main heat exchanger; SC, subcooler; C1, lower tower; MCE, main condenser evaporator; OP, product liquid oxygen pump; C2, upper tower; CAP, circulating liquid oxygen pump; C3, crude argon tower; CAC, crude argon tower condenser; C4, refined argon tower; PAC, refined argon tower condenser; ACP, circulating liquid argon pump; PAE, refined argon evaporator; ETCE, boost end aftercooler. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] like Figure 1 As shown, a liquid argon circulation air separation unit that prevents nitrogen plugging comprises:

[0028] Raw material compression system, which includes air compressor MAC and booster BAC;

[0029] Pre-cooling and purification system, which includes air cooling tower AC, water cooling tower EC, chiller RU, cooling water pump WP1, chilled water pump WP2 and purifier MS1 / MS2;

[0030] The low-temperature separation system includes an expander boosting end ETC, an expander expansion end ET (in this embodiment, one expander is provided, ETC is the boosting end of the expander, and ET is the expansion end of the expander), a main heat exchanger MEH, a subcooler SC, a lower column C1, a main condenser evaporator MCE, a product liquid oxygen pump OP, an upper column C2, a circulating liquid oxygen pump CAP, a crude argon column C3, a crude argon column condenser CAC, a refined argon column C4, a refined argon column condenser PAC, a circulating liquid argon pump ACP and a refined argon evaporator PAE, wherein:

[0031] The output end of the air compressor MAC is connected to the input end of the air cooling tower AC, the air cooling tower AC is connected to the chiller RU and the cooling water pump WP1, the chiller RU is connected to the chilled water pump WP2, the chilled water pump WP2 is connected to the water cooling tower EC, the air cooling tower AC is connected to the purifier MS1 / MS2, one pipeline of the purifier MS1 / MS2 is connected to the lower tower C1 through the main heat exchanger MEH, and the other pipeline is connected to the booster BAC.

[0032] One path from the booster BAC is connected to the booster end ETC of the expander, which is in turn connected to the booster end aftercooler ETCE, which is in turn connected to the main heat exchanger MEH. The main heat exchanger MEH is in contact with the expansion end ET of the expander, which is in contact with the lower tower C1. Another path is connected to the main heat exchanger MEH, which is in contact with the lower tower C1 via a throttle valve.

[0033] The two output ends of the lower tower C1 are connected to the input ends of the main heat exchanger MEH and the refined argon evaporator PAE respectively;

[0034] The five pipelines of the lower tower C1 are all connected to the subcooler SC and then divided into eight pipelines after passing through the cooler SC. Four of them are connected to the upper tower C2 respectively, and the other two pipelines extend out of the cold box as liquid nitrogen product pipelines and liquid oxygen product pipelines respectively. The other two pipelines are connected to the crude argon tower condenser CAC and the refined argon tower condenser PAC respectively.

[0035] A main condenser evaporator MCE is provided between the lower tower C1 and the upper tower C2. The main condenser evaporator MCE is connected to the product liquid oxygen pump OP, and the product liquid oxygen pump OP is connected to the main heat exchanger MEH. The two pipelines at the top of the upper tower C2 are connected to the main heat exchanger MEH after passing through the cooler SC respectively.

[0036] Crude argon column C3 is connected to the circulating liquid oxygen pump CAP. A crude argon column condenser CAC is installed at the top of crude argon column C3. The circulating liquid oxygen pump CAP is connected to the upper column C2. Two pipelines of the crude argon column condenser CAC are connected to the upper column C2 and the subcooler SC, respectively. A refined argon column C4 is equipped with a refined argon column condenser PAC at the top and a refined argon evaporator PAE at the bottom. The refined argon column condenser PAC is connected to the upper column C2 and the subcooler SC, respectively. The circulating liquid argon pump ACP is connected to the crude argon column condenser CAC. Three pipelines of the refined argon evaporator PAE are connected to the upper column C2, the lower column C1, and the circulating liquid argon pump ACP, respectively. One pipeline of the refined argon evaporator PAE serves as the liquid argon product pipeline to the outside of the cold box.

[0037] Working principle:

[0038] 1. After being pressurized to a certain pressure by the air compressor MAC, the raw air enters the air cooling tower AC, where it comes into direct contact with cooling water from the circulating water system, further cooled by the chiller EC and the water cooling tower RU, achieving graded cooling. The cooled processed air then enters the purifier MS1 / MS2, where it is adsorbed to remove residual water, carbon dioxide, and hydrocarbons.

[0039] 2. A portion of the dry, clean air enters the main heat exchanger EH directly, where it is cooled to near saturation temperature and then enters the lower tower C1. The remaining air is compressed by the booster compressor BAC and split into two streams. One stream is sent directly to the main heat exchanger MEH to provide vaporization heat for the liquid oxygen. After cooling to liquid air, it enters the lower tower C1 after throttling. The other stream enters the expander booster end ETC, where it is boosted and cooled, then enters the main heat exchanger MEH. After cooling to a certain temperature, it is extracted to the expander expansion end ET for expansion, and then enters the lower tower C1.

[0040] 3. High-purity liquid nitrogen and nitrogen gas are obtained at the top of lower column C1. A portion of the liquid nitrogen serves as reflux for the distillation of lower column C1. The remaining liquid nitrogen passes through the cooler SC, and a portion is throttled to enter the upper column C2, providing reflux for the distillation of upper column C2. A portion is sent to the refined argon column condenser PAC as a cold source, and the remaining portion is sent to the cold outer column as liquid nitrogen product. A portion of the nitrogen gas at the top of lower column C1 is sent to the refined argon evaporator PAE as a heat source. An appropriate amount is then extracted and sent to the main heat exchanger MEH for reheating before being sent to the pipeline network as nitrogen product. The dirty liquid nitrogen in the upper part of lower column C1 passes through the cooler SC and is throttled to enter the upper column C2, providing reflux for the distillation of upper column C2. The lean liquid air in the lower part of lower column C1 passes through the cooler SC and is throttled to enter the upper column C2 for distillation. The oxygen-rich liquid at the bottom of lower column C1 passes through the cooler SC, and a portion of the throttled liquid enters the upper column C2 for distillation, while the remaining portion is sent to the crude argon column condenser CAC as a cold source. Liquid oxygen with higher purity is obtained in the main condenser evaporator MCE at the bottom of the upper tower C2. An appropriate amount is extracted and pressurized to the required pressure by the product liquid oxygen pump OP and sent to the main heat exchanger MEH for heat exchange with high-pressure air. It is vaporized into pressurized oxygen product and sent to the oxygen product pipeline network. Part of the liquid oxygen is supercooled by the cooler SC and sent downstream as a liquid product. The argon fraction is extracted from the middle and lower part of the upper tower C2 and sent to the bottom of the crude argon tower C3 as rising steam.

[0041] 4. The rising steam from the crude argon column C3 exchanges heat with oxygen-rich liquid air in the crude argon column condenser CAC. The oxygen-rich liquid air on the evaporation side is heated and evaporated into oxygen-rich gas, which is then sent from the top of the crude argon column condenser CAC to the middle of the upper column C2. The unevaporated oxygen-rich liquid air is sent from the bottom of the crude argon column condenser CAC to the middle of the upper column C2. The rising steam from the condensation side is condensed into crude liquid argon, most of which participates in rectification as the reflux liquid of the crude argon column C3. Oxygen-rich liquid air is obtained at the bottom of the crude argon column C3 and sent to the lower middle part of the upper column C2 via the circulating liquid oxygen pump CAP. A small portion is sent to the middle of the refined argon column C4 to participate in rectification.

[0042] 5. In the refined argon column condenser PAC, crude argon exchanges heat with liquid nitrogen, and dirty nitrogen is obtained on the evaporation side and sent to the dirty nitrogen main pipe. The reflux liquid obtained on the condensation side participates in rectification, and liquid argon is obtained at the bottom of the refined argon column C4; liquid argon exchanges heat with nitrogen in the refined argon evaporator PAE, and the nitrogen is liquefied and sent to the upper column C2, and the liquid argon is evaporated as rising steam; an appropriate amount of liquid argon is extracted and sent to the crude argon column condenser CAC through the liquid argon circulation pump ACP. The nitrogen content in the crude liquid argon is controlled to prevent nitrogen plugging, and a part of it is sent out of the cold box as liquid argon product.

[0043] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A liquid argon circulation air separation unit that prevents nitrogen plugging, characterized in that: include: a feedstock compression system, which includes a MAC and a booster air compressor (BAC); Precooling and purification system, which includes air cooling tower (AC), water cooling tower (EC), chiller (RU), cooling water pump (WP1), chilled water pump (WP2) and purifier (MS1 / MS2); The low-temperature separation system includes an expander booster end (ETC), an expander expansion end (ET), a main heat exchanger (MEH), a subcooler (SC), a lower tower (C1), a main condenser evaporator (MCE), a product liquid oxygen pump (OP), an upper tower (C2), a circulating liquid oxygen pump (CAP), a crude argon tower (C3), a crude argon tower condenser (CAC), a refined argon tower (C4), a refined argon tower condenser (PAC), a circulating liquid argon pump (ACP) and a refined argon evaporator (PAE), wherein: The output end of the air compressor (MAC) is communicated with the input end of the air cooling tower (AC), the air cooling tower (AC) is communicated with the chiller unit (RU) and the cooling water pump (WP1), the chilled water pump (WP2) is communicated with the water cooling tower (EC), and the air cooling tower (AC) is communicated with the purifier (MS1 / MS2); The booster (BAC) is connected to the boosting end (ETC) of the expander through one path, the main heat exchanger (MEH) is connected to the expansion end (ET) of the expander, and the expansion end (ET) of the expander is connected to the lower tower (C1); the other path is connected to the main heat exchanger (MEH), and the main heat exchanger (MEH) is connected to the lower tower (C1) through a throttle valve; The two output ends of the lower tower (C1) are respectively connected to the input ends of the main heat exchanger (MEH) and the refined argon evaporator (PAE); The five pipelines of the lower tower (C1) are all connected to the subcooler (SC) and then divided into eight pipelines after passing through the cooler (SC), of which four pipelines are respectively connected to the upper tower (C2), the other two pipelines are respectively extended out of the cold box as liquid nitrogen product pipelines and liquid oxygen product pipelines, and the other two pipelines are respectively connected to the crude argon tower condenser (CAC) and the refined argon tower condenser (PAC); A main condenser evaporator (MCE) is provided between the lower tower (C1) and the upper tower (C2), and the main condenser evaporator (MCE) is connected to the product liquid oxygen pump (OP); The crude argon column (C3) is connected to a circulating liquid oxygen pump (CAP), which is connected to the upper column (C2). The two pipelines of the crude argon column condenser (CAC) are respectively connected to the upper column (C2) and the subcooler (SC). The refined argon column (C4) is provided with a refined argon column condenser (PAC) at the top and a refined argon evaporator (PAE) at the bottom. The refined argon column condenser (PAC) is respectively connected to the upper column (C2) and the subcooler (SC). The circulating liquid argon pump (ACP) is connected to the crude argon column condenser (CAC).

2. The liquid argon circulation air separation unit with nitrogen plugging prevention according to claim 1, characterized in that: The expander supercharging end (ETC) is communicated with the supercharging end aftercooler (ETCE), and the supercharging end aftercooler (ETCE) is communicated with the main heat exchanger (MEH).

3. The liquid argon circulation air separation unit with nitrogen plugging prevention according to claim 1, characterized in that: One pipeline of the purifier (MS1 / MS2) is connected to the lower tower (C1) through the main heat exchanger (MEH), and the other pipeline is connected to the booster (BAC).

4. The liquid argon circulation air separation unit with nitrogen plugging prevention according to claim 1, characterized in that: The chiller unit (RU) is connected to the chilled water pump (WP2).

5. The liquid argon circulation air separation unit with nitrogen plugging prevention according to claim 1, characterized in that: The product liquid oxygen pump (OP) is connected to the main heat exchanger (MEH), and the two pipelines at the top of the upper tower (C2) are connected to the main heat exchanger (MEH) after passing through the cooler (SC).

6. The liquid argon circulation air separation unit with nitrogen plugging prevention according to claim 1, characterized in that: A crude argon column condenser (CAC) is provided on the top of the crude argon column (C3).

7. The liquid argon circulation air separation unit with nitrogen plugging prevention according to claim 1, characterized in that: The three pipelines of the refined argon evaporator (PAE) are respectively connected to the upper tower (C2), the lower tower (C1) and the circulating liquid argon pump (ACP).

8. The liquid argon circulation air separation unit with nitrogen plugging prevention according to claim 1, characterized in that: One pipeline of the refined argon evaporator (PAE) is used as a liquid argon product pipeline to the outside of the cold box.

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