An argon recovery device cold box for argon-hydrogen full recovery and a method of using the same

Abstract

This invention relates to a cold box for argon recovery device with complete argon-hydrogen recovery and its usage method. It includes a cold box containing an argon purification tower, a waste gas distillation tower, a nitrogen production distillation tower, a main heat exchanger, an expander, and a nitrogen production condenser / evaporator, all connected by pipelines. Two main heat exchangers are installed: a first main heat exchanger and a second main heat exchanger. Two expanders are also installed: a first expander and a second expander. One expander is in use while the other is on standby, and they are switched between each other. The waste gas distillation tower is used for cold box capacity balancing, transferring excess cold energy from the nitrogen production system to the argon separation system. The application of this cold box not only maintains a near 100% argon recovery rate and minimizes liquid argon backflow, but also recovers and reuses hydrogen from the waste gas, thereby reducing equipment investment and operating power consumption. It has significant practical value and economic benefits.

Description

Technical Field

[0001] This invention relates to gas separation technology, specifically, to the design and improvement of the cold box of an argon recovery device, the addition of a nitrogen extraction port to the waste gas distillation tower, and the use of a cryogenic distillation method to design an argon recovery device cold box for complete argon and hydrogen recovery and its application method, belonging to the field of cryogenic technology. Background Technology

[0002] Argon recovery units, by recovering the sealed argon gas from single crystal furnaces and performing decarbonization and deoxygenation pretreatment and cryogenic distillation separation, allow for the recycling of argon gas, significantly reducing the production cost of single crystal rods and enabling the industrial production of single crystal rods. Hydrogen-free argon recovery units, however, do not recover oxygen-containing argon gas collected by auxiliary pumps, resulting in high argon consumption and frequent liquid argon replenishment, leading to poor economic efficiency. Therefore, later-built argon recovery units for single crystal furnaces all adopt hydrogen-based processes. Hydrogen-based argon recovery units involve front-end processes such as dust removal and pressurization of the raw gas, compressor compression, decarbonization and drying, hydrogenation for deoxygenation and moisture adsorption, followed by cryogenic separation in a cold box.

[0003] In recent years, with the development of the social economy and the advancement of industrial technology, the market demand for high-purity argon has been increasing, and the requirements have become more stringent. The development of the photovoltaic and semiconductor industries has also led to a simultaneous increase in the number and scale of argon recovery devices in operation. With the application of two-stage separation of argon gas as raw material in the cold box of argon recovery devices, the argon recovery rate in the cold box is close to 100%. To further reduce equipment investment and operating power consumption, and to recover and utilize hydrogen from the waste gas, a cold box for argon recovery device with complete argon-hydrogen recovery and its usage method are designed. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a cold box for an argon recovery device with complete argon-hydrogen recovery and its usage method. This invention improves the argon recovery rate of the cold box while reducing equipment investment and operating power consumption through a new process. The application of this cold box not only maintains a near 100% argon recovery rate and minimizes liquid argon backfilling, but also recovers and reuses hydrogen from waste gas, thereby reducing equipment investment and operating power consumption. It has significant practical value and economic benefits.

[0005] This invention is achieved through the following technical solution: a cold box for an argon recovery device with complete argon-hydrogen recovery, comprising a cold box, an argon purification tower, a waste gas distillation tower, a nitrogen production distillation tower, a main heat exchanger, an expander, and a nitrogen production condenser-evaporator, all connected to each other via pipelines. Two main heat exchangers are provided, designated as a first main heat exchanger and a second main heat exchanger. Two expanders are also provided, designated as a first expander and a second expander. One expander is in use while the other is on standby, and they are switched between each other. The waste gas distillation tower is used for cold box cooling balance, transferring excess cooling capacity from the nitrogen production system to the argon separation system.

[0006] Preferably, the argon purification tower consists of an upper purification tower condenser, a lower purification tower evaporator, and an intermediate tower section, and the waste gas distillation tower consists of an upper waste gas distillation tower condenser, a lower waste gas distillation tower evaporator, and an intermediate tower section.

[0007] Preferably, the nitrogen-generating distillation column can be arranged together with the nitrogen-generating condenser-evaporator or separately.

[0008] Preferably, the first main heat exchanger is provided with a first raw material argon gas inlet pipe, a nitrogen-hydrogen-argon circulation pipe, a non-condensable waste gas outlet pipe, a low-pressure nitrogen outlet pipe, and an auxiliary tower waste nitrogen outlet pipe; the second main heat exchanger is provided with a second raw material argon gas inlet pipe, an oxygen-enriched gas outlet pipe, a purified air inlet pipe, a nitrogen outlet pipe, and a product argon gas outlet pipe.

[0009] Preferably, the cold box is also connected to a liquid argon return pipeline, which is connected to the argon purification tower and the waste gas distillation tower. The nitrogen generator condenser evaporator is also provided with a product nitrogen pipeline connected to the outside of the cold box.

[0010] A method for using a cold box of an argon recovery device for complete argon-hydrogen recovery, the method comprising the following steps:

[0011] Step 1: The crude argon gas is divided into two streams and enters the first main heat exchanger and the second main heat exchanger respectively for pre-cooling and cooling. After cooling, they are combined and enter the evaporator of the argon purification tower. Some of the non-condensable gas is reheated through the first main heat exchanger and exits the cold box, while the rest is condensed into crude liquid argon.

[0012] Step 2: The non-condensable gas exiting the cold box is mixed with supplemental hydrogen through a circulating compressor and then enters the hydrodeoxygenation system for recycling;

[0013] Step 3: After throttling, the crude liquid argon enters the argon purification tower to participate in distillation. In the argon purification tower, high-purity liquid argon is obtained at the bottom and hydrogen-containing argon sludge nitrogen is obtained at the top.

[0014] Step 4: The hydrogen-containing argon waste nitrogen is condensed in the condenser of the purification tower, and the condensed liquid is used as the reflux liquid of the argon purification tower; part of the non-condensable gas is sent to the waste gas stripping tower for further distillation and separation.

[0015] Step 5: Non-condensable gas is fed into the lower part of the waste gas stripping tower. Through distillation separation, the bottom rich liquid argon is heated and evaporated by nitrogen from the nitrogen production distillation tower, and used as the rising gas of the distillation tower; the top gas is condensed into liquid by liquid nitrogen and used as the reflux liquid of the waste gas stripping tower. Sludge nitrogen is extracted from the upper part of the tower and used as waste gas. It is reheated in the first main heat exchanger and discharged from the cold box or reused. The hydrogen-containing non-condensable gas at the top of the tower is reheated in the first main heat exchanger and discharged from the cold box to enter the argon recovery unit for recycling.

[0016] Step 6: The liquid nitrogen condensed in the evaporator of the waste gas stripping tower is throttled into the condenser of the waste gas stripping tower and evaporated as a cold source. A portion of crude liquid argon is drawn from the bottom of the waste gas stripping tower as reflux liquid at the top of the argon purification tower. At the same time, liquid nitrogen is drawn from the nitrogen generator evaporator and throttled into the condenser of the waste gas stripping tower to supplement the cooling capacity and increase the reflux ratio of the waste gas stripping tower.

[0017] Step 7: The evaporated low-pressure nitrogen gas is reheated by the first main heat exchanger and exits the cold box as regeneration gas for the deoxygenation purifier.

[0018] Step 8: The high-purity liquid argon obtained from the argon purification tower is throttled and enters the purification tower condenser. The liquid argon is evaporated, and then reheated through the second main heat exchanger before exiting the cold box and being sent to the product argon compressor.

[0019] Step 9: After precooling in the second main heat exchanger, the air enters the nitrogen distillation column. Through distillation, oxygen-enriched liquid air is obtained at the bottom and high-purity nitrogen is obtained at the top. A portion of the nitrogen is extracted from the top of the nitrogen distillation column, reheated in the second main heat exchanger, and then discharged from the cold box for user use and as regeneration gas for the deoxygenation purifier.

[0020] Step 10: After throttling, the oxygen-enriched liquid air enters the nitrogen generator condenser evaporator, evaporates into oxygen-enriched air, and then is reheated to a certain temperature through the second main heat exchanger before entering the first and second expanders for expansion and refrigeration to provide cooling capacity for the cold box. After expansion, the oxygen-enriched air is reheated through the second main heat exchanger and exits the cold box as regeneration gas for the air purifier and decarbonization purifier.

[0021] Step 11: In the nitrogen-generating condenser-evaporator, nitrogen gas is condensed into liquid nitrogen. Most of it is used as reflux liquid in the nitrogen-generating distillation column, part of it is used as a cold source for the condenser of the waste gas stripping column, and part of it is sent to the liquid nitrogen storage tank as product liquid nitrogen.

[0022] Step 12: In order to maintain the balance of argon usage and cold box cooling capacity, a portion of liquid argon is reinjected into the argon purification tower.

[0023] The beneficial effects of this invention are as follows: This invention utilizes the principle of low-temperature distillation separation and performs secondary distillation on the non-condensable waste gas discharged from the primary distillation of the argon tower, achieving an argon recovery rate of over 99.95% in the cold box of the argon recovery device (when the feed gas contains 1.2% oxygen). The hydrogen-containing non-condensable gas at the top is reheated and then enters the gas holder for recycling. The use of this invention maintains the ultra-high argon-hydrogen recovery rate and low liquid argon back-injection volume of the argon recovery device's cold box, while reducing the investment cost and operational complexity of the cold box. The increased argon recovery rate and reduced liquid argon back-injection volume reduce the cost of purchasing liquid argon and decrease dependence on the liquid argon market. Simultaneously, the recovery and recycling of hydrogen reduces the amount of hydrogen produced by water electrolysis, lowering electricity consumption. For regions with a shortage of liquid argon, its economic benefits are even more significant and considerable; therefore, this invention has excellent practical value and economic benefits. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0025] N2 is the first raw material argon inlet pipe; N3 is the nitrogen-hydrogen-argon circulating gas inlet pipe; N4 is the product argon outlet pipe; N5 is the non-condensable waste gas outlet pipe; N6 is the return injection liquid argon pipeline; N7 is the purified air inlet pipe; N8 is the nitrogen outlet pipe; N9 is the oxygen-enriched gas outlet pipe; N10 is the product nitrogen pipeline; N11 is the low-pressure nitrogen outlet pipe; and N12 is the auxiliary tower waste nitrogen outlet pipe. Detailed Implementation

[0026] To enable those skilled in the art to more clearly understand the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] In the description of this invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "lateral", and "vertical" is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing this invention, and is not intended to indicate or imply that the device or component referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0028] The invention will now be described in detail with reference to the accompanying drawings: Figure 1 As shown, an argon recovery device cold box for complete argon-hydrogen recovery includes a cold box C501. The cold box C501 houses an argon purification tower, a waste gas distillation tower, a nitrogen production distillation tower, a main heat exchanger, an expander, and a nitrogen production condenser / evaporator, all connected by pipelines. Two main heat exchangers are provided: a first main heat exchanger E21 and a second main heat exchanger E22. Two expanders are also provided: a first expander ET501 and a second expander ET502. One expander is in use while the other is on standby, and they are switched between each other. The waste gas distillation tower is used for cold box cooling balance, transferring excess cooling capacity from the nitrogen production system to the argon separation system.

[0029] The argon purification tower C21 consists of an upper purification tower condenser, a lower purification tower evaporator, and an intermediate tower section. The waste gas distillation tower consists of an upper waste gas distillation tower condenser, a lower waste gas distillation tower evaporator, and an intermediate tower section. The nitrogen production distillation tower can be arranged together with the nitrogen production condenser / evaporator or separately. The first main heat exchanger E21 is equipped with a first raw material argon gas inlet pipe N2, a nitrogen-hydrogen-argon circulation gas pipe N3, a non-condensable waste gas outlet pipe N5, a low-pressure nitrogen outlet pipe N11, and an auxiliary tower waste nitrogen outlet pipe N12. The second main heat exchanger E22 is equipped with a second raw material argon gas inlet pipe N1, an oxygen-enriched gas outlet pipe N9, a purified air inlet pipe N7, a nitrogen outlet pipe N8, and a product argon gas outlet pipe N4.

[0030] The cold box C501 is also connected to a liquid argon return pipeline N6, which is connected to the argon purification tower C21 and the waste gas distillation tower C23. The nitrogen generator condenser evaporator K23 is also connected to a product nitrogen pipeline N10 that connects to the outside of the cold box.

[0031] A method for using a cold box of an argon recovery device for complete argon-hydrogen recovery, the method comprising the following steps:

[0032] Step 1: The crude argon gas is divided into two streams and enters the first main heat exchanger E21 and the second main heat exchanger E22 for pre-cooling. After cooling, they are combined and enter the argon purification tower evaporator K21. Some of the non-condensable gas is reheated through the first main heat exchanger E21 and exits the cold box, while the rest is condensed into crude liquid argon.

[0033] Step 2: The non-condensable gas exiting the cold box is mixed with supplemental hydrogen through a circulating compressor and then enters the hydrodeoxygenation system for recycling;

[0034] Step 3: After throttling, the crude liquid argon enters the argon purification tower C21 to participate in distillation. In the argon purification tower C21, high-purity liquid argon is obtained at the bottom and hydrogen-containing argon sludge nitrogen is obtained at the top.

[0035] Step 4: The hydrogen-containing argon waste nitrogen is condensed in the condenser K22 of the purification tower, and the condensed liquid is used as the reflux liquid of the argon purification tower C21; part of the non-condensable gas is sent to the waste gas stripping tower C23 for further distillation and separation.

[0036] Step 5: Non-condensable gas is fed into the lower part of the waste gas stripping tower C23. Through distillation separation, the bottom rich liquid argon is heated and evaporated by nitrogen from the nitrogen production distillation tower C22, and used as the rising gas of the distillation tower; the top gas is condensed into liquid by liquid nitrogen and used as the reflux liquid of the waste gas stripping tower C23. Sludge nitrogen is extracted from the upper part of the tower and used as waste gas. It is reheated in the first main heat exchanger E21 and discharged from the cold box or reused. The hydrogen-containing non-condensable gas at the top of the tower is reheated in the first main heat exchanger E21 and discharged from the cold box to enter the argon recovery unit for recycling.

[0037] Step 6: The liquid nitrogen condensed in the evaporator K24 of the waste gas stripping tower is throttled into the condenser K25 of the waste gas stripping tower and evaporated as a cold source. A portion of crude liquid argon is drawn from the bottom of the waste gas stripping tower C23 as the reflux liquid at the top of the argon purification tower C21. At the same time, liquid nitrogen is drawn from the nitrogen generator evaporator K23 and throttled into the condenser K25 of the waste gas stripping tower to supplement the cooling capacity and increase the reflux ratio of the waste gas stripping tower C23.

[0038] Step 7: The evaporated low-pressure nitrogen gas is reheated by the first main heat exchanger E21 and exits the cold box C501 as the regeneration gas of the deoxygenation purifier.

[0039] Step 8: The high-purity liquid argon obtained from the argon purification tower C21 is throttled and enters the purification tower condenser K22. The liquid argon is evaporated and then reheated through the second main heat exchanger E22 before exiting the cold box C501 and being sent to the product argon compressor.

[0040] Step 9: After pre-cooling in the second main heat exchanger E22, the air enters the nitrogen distillation column C22. Through distillation, oxygen-enriched liquid air is obtained at the bottom and high-purity nitrogen is obtained at the top. Part of the nitrogen is extracted from the top of the nitrogen distillation column C22, reheated in the second main heat exchanger E22, and discharged from the cold box for user use and as regeneration gas for the deoxygenation purifier.

[0041] Step 10: After throttling, the oxygen-enriched liquid air enters the nitrogen generator condenser evaporator K23, where it evaporates into oxygen-enriched air. It then passes through the second main heat exchanger E22 and is reheated to a certain temperature before entering the first expander ET501 and the second expander ET502 for expansion and refrigeration, providing cooling capacity for the cold box. After expansion, the oxygen-enriched air passes through the second main heat exchanger E22 and is reheated before exiting the cold box, serving as regeneration gas for the air purifier and decarbonization purifier.

[0042] Step 11: In the nitrogen condenser K23, nitrogen gas is condensed into liquid nitrogen. Most of it is used as reflux liquid in the nitrogen distillation column C22, part of it is used as a cold source for the waste gas stripping column condenser K25, and part of it is sent to the liquid nitrogen storage tank as product liquid nitrogen.

[0043] Step 12: To maintain the balance of argon usage and cold box cooling capacity, a portion of liquid argon is reinjected into the argon purification tower C21. The condenser and main heat exchanger in this invention are both plate-fin heat exchangers.

[0044] Compared to current argon recovery unit cold boxes, this invention aims to improve argon-hydrogen recovery rates by reducing the release of argon and hydrogen. The invention employs the following methods to enhance the argon-hydrogen recovery rate of the cold box: 1. A non-condensable waste gas distillation column is added to the existing argon recovery unit cold box. This column has a reboiler at the bottom, using nitrogen from the nitrogen tower as a heat source; a condenser at the top, using liquid nitrogen as a cold source. To obtain usable crude hydrogen at the top, waste nitrogen is extracted from the upper side stream of this column. 2. Due to the increased argon recovery rate, the liquid argon backflow needs to be reduced. To maintain the unit's cooling balance, a reflux gas expander is added to the cold box.

[0045] The design features of this invention are as follows:

[0046] 1) It involves secondary separation of waste gas, which reduces the hydrogen and argon content in the waste gas and increases the amount of hydrogen and argon recovered;

[0047] 2) By adjusting the condenser and evaporator of the waste gas distillation tower, the reflux ratio can be increased, effectively improving the argon recovery rate.

[0048] 3) The choice of cold fluid for the condenser of the waste gas distillation tower is important. Using liquid nitrogen can ensure that a certain temperature difference is maintained between the liquid nitrogen and the waste gas at the top of the tower.

[0049] 4) A nitrogen extraction system is installed in the waste gas stripping tower C23 to achieve a high concentration of hydrogen in the non-condensable gas at the top, which can be recycled.

[0050] The specific embodiments described herein are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A cold box for an argon recovery device with complete argon-hydrogen recovery, comprising a cold box, characterized in that: The cold box is equipped with an argon purification tower, a waste gas distillation tower, a nitrogen production distillation tower, a main heat exchanger, an expander, and a nitrogen production condenser-evaporator, all connected by pipelines. There are two main heat exchangers, namely the first main heat exchanger and the second main heat exchanger, and there are also two expanders, namely the first expander and the second expander. One expander is in use while the other is on standby, and they can be switched between each other. The waste gas distillation tower is used to balance the cooling capacity of the cold box, transferring excess cooling capacity from the nitrogen production system to the argon separation system. The first main heat exchanger is provided with a first raw material argon gas inlet pipe, a nitrogen-hydrogen-argon circulation pipe, a non-condensable waste gas outlet pipe, a low-pressure nitrogen outlet pipe, and an auxiliary tower waste nitrogen outlet pipe. The second main heat exchanger is provided with a second raw material argon gas inlet pipe, an oxygen-enriched gas outlet pipe, a purified air inlet pipe, a nitrogen outlet pipe, and a product argon gas outlet pipe. The cold box is also connected to a liquid argon return pipeline, which is connected to the argon purification tower and the waste gas distillation tower. The nitrogen generator condenser evaporator is also connected to a product nitrogen pipeline that connects to the outside of the cold box.

2. The cold box of the argon recovery device for complete argon-hydrogen recovery according to claim 1, characterized in that: The argon purification tower consists of an upper purification tower condenser, a lower purification tower evaporator, and an intermediate tower section. The waste gas distillation tower consists of an upper waste gas distillation tower condenser, a lower waste gas distillation tower evaporator, and an intermediate tower section.

3. The cold box of the argon recovery device for complete argon-hydrogen recovery according to claim 1, characterized in that: The nitrogen-generating distillation column can be installed together with the nitrogen-generating condenser-evaporator or arranged separately.

4. A method of using the cold box of an argon recovery device for total argon-hydrogen recovery according to any one of claims 1-3, characterized in that: The method includes the following steps: Step 1: The crude argon gas is divided into two streams and enters the first main heat exchanger and the second main heat exchanger respectively for pre-cooling and cooling. After cooling, they are combined and enter the evaporator of the argon purification tower. Some of the non-condensable gas is reheated through the first main heat exchanger and exits the cold box, while the rest is condensed into crude liquid argon. Step 2: The non-condensable gas exiting the cold box is mixed with supplemental hydrogen through a circulating compressor and then enters the hydrodeoxygenation system for recycling; Step 3: After throttling, the crude liquid argon enters the argon purification tower to participate in distillation. In the argon purification tower, high-purity liquid argon is obtained at the bottom and hydrogen-containing argon waste nitrogen is obtained at the top. Step 4: The hydrogen-containing argon waste nitrogen is condensed in the condenser of the purification tower, and the condensed liquid is used as the reflux liquid of the argon purification tower; part of the non-condensable gas is sent to the waste gas stripping tower for further distillation and separation. Step 5: Non-condensable gas is fed into the lower part of the waste gas stripping tower. Through distillation separation, the bottom rich liquid argon is heated and evaporated by nitrogen from the nitrogen production distillation tower, and used as the rising gas of the distillation tower; the top gas is condensed into liquid by liquid nitrogen and used as the reflux liquid of the waste gas stripping tower. Sludge nitrogen is extracted from the upper part of the tower and used as waste gas. It is reheated in the first main heat exchanger and discharged from the cold box or reused. The hydrogen-containing non-condensable gas at the top of the tower is reheated in the first main heat exchanger and discharged from the cold box to enter the argon recovery unit for recycling. Step 6: The liquid nitrogen condensed in the evaporator of the waste gas stripping tower is throttled into the condenser of the waste gas stripping tower and evaporated as a cold source. A portion of crude liquid argon is drawn from the bottom of the waste gas stripping tower as reflux liquid at the top of the argon purification tower. At the same time, liquid nitrogen is drawn from the nitrogen generator evaporator and throttled into the condenser of the waste gas stripping tower to supplement the cooling capacity and increase the reflux ratio of the waste gas stripping tower. Step 7: The evaporated low-pressure nitrogen gas is reheated by the first main heat exchanger and exits the cold box as regeneration gas for the deoxygenation purifier. Step 8: The high-purity liquid argon obtained from the argon purification tower is throttled and enters the purification tower condenser. The liquid argon is evaporated, and then reheated through the second main heat exchanger before exiting the cold box and being sent to the product argon compressor. Step 9: After precooling in the second main heat exchanger, the air enters the nitrogen distillation column. Through distillation, oxygen-enriched liquid air is obtained at the bottom and high-purity nitrogen is obtained at the top. A portion of the nitrogen is extracted from the top of the nitrogen distillation column, reheated in the second main heat exchanger, and then discharged from the cold box for user use and as regeneration gas for the deoxygenation purifier. Step 10: After throttling, the oxygen-enriched liquid air enters the nitrogen generator condenser evaporator, evaporates into oxygen-enriched air, and then is reheated to a certain temperature through the second main heat exchanger before entering the first and second expanders for expansion and refrigeration to provide cooling capacity for the cold box. After expansion, the oxygen-enriched air is reheated through the second main heat exchanger and exits the cold box as regeneration gas for the air purifier and decarbonization purifier. Step 11: In the nitrogen-generating condenser-evaporator, nitrogen gas is condensed into liquid nitrogen. Most of it is used as reflux liquid in the nitrogen-generating distillation column, part of it is used as a cold source for the condenser of the waste gas stripping column, and part of it is sent to the liquid nitrogen storage tank as product liquid nitrogen. Step 12: In order to maintain the balance of argon usage and cold box cooling capacity, a portion of liquid argon is reinjected into the argon purification tower.

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