Gas purification system and method for cold and heat cyclic utilization

Abstract

The invention provides a gas purification system and method for cold and heat cyclic utilization. The system comprises a plurality of purification towers, a heat exchange medium circulation pipeline and a gas pipeline, wherein the heat exchange medium circulation pipeline and the gas pipeline flow through the purification towers; the heat exchange medium circulating pipeline comprises a preheating sub-pipeline, a main cooling sub-pipeline and a cold supplementing sub-pipeline; the gas pipeline comprises a gas inlet sub-pipeline and a gas outlet sub-pipeline; and the preheating sub-pipeline and the main cooling sub-pipeline respectively flow through the upper part and the lower part of the purification tower. The heat pump technology serves as a core, the problems that a traditional gas purification system is large in overall equipment investment, large in circulating water amount, high in energy consumption and incapable of supplying heat and refrigerating heat to drying towers in different periodic states at the same time are solved through combined cooling and heating and cyclic utilization, dual optimization of energy consumption and equipment cost is achieved, and the energy consumption and the equipment cost are improved. The energy efficiency bottleneck of a traditional purification system is broken through.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology and relates to a gas purification system and method. Background Art

[0002] With the continuous development of the economy and society, energy and environmental issues are becoming increasingly serious, resulting in an increasing demand for green energy hydrogen. The hydrogen produced by hydrogen production equipment needs to enter a purification system to remove moisture and impurities. However, mainstream hydrogen purification systems use two or more drying towers, which alternate between working cycles, regeneration cycles, and cooling cycles. During the regeneration cycle, electric heating equipment is required to provide heat, and during the cooling cycle, public auxiliary equipment is required to provide cooling water or chilled water to reduce the drying tower in the cooling cycle to room temperature. This requires the simultaneous introduction of heat source Q1 and cold source Q2 from the outside, resulting in large overall equipment investment, large circulating water volume, and high energy consumption. Currently, the electricity cost of hydrogen purification accounts for approximately 50-80% of the total life cycle cost of hydrogen production by electrolysis of water. In order to improve the economic benefits of hydrogen energy, it is urgent to reduce the energy consumption of hydrogen purification.

[0003] Publication number CN217627625U discloses a hydrogen purification device and a water electrolysis hydrogen production system, which collects heat from a drying tower in a regeneration cycle through a heat exchanger and then utilizes it through heating or preheating. Publication number CN115709971A discloses a hydrogen purification system and control method, which switches the drying device in the auxiliary state and the regeneration state to standby by switching the pipeline between the regeneration state, making the hydrogen purification system suitable for water electrolysis hydrogen production equipment with fluctuating or intermittent hydrogen production. Currently, heat pump technology can only utilize heat energy or cold energy in a certain stage, and cannot utilize heat energy and cold energy simultaneously. Considering heat loss, the energy efficiency ratio of simple electric heating or heat exchanger is less than 1, and it cannot meet the requirements of simultaneously heating and cooling the drying tower in different cycle states. In addition, the purification process of other gases such as nitrogen and oxygen also has the same problems. Summary of the Invention

[0004] In order to solve the problems of traditional gas purification systems in the background technology, such as large overall equipment investment, large circulating water volume, high energy consumption, and inability to simultaneously provide heating and cooling for drying towers in different cycle states, the present invention provides a gas purification system and method for hot and cold recycling.

[0005] The system of the present invention comprises a plurality of purification towers, and heat exchange medium circulation pipelines and gas pipelines flowing through the plurality of purification towers; The heat exchange medium circulation pipeline includes a preheating sub-pipeline, a main cooling sub-pipeline and a supplementary cooling sub-pipeline; The gas pipeline includes an inlet sub-pipeline and an outlet sub-pipeline; The preheating sub-pipeline and the main cooling sub-pipeline flow through the upper part and the lower part of the purification tower respectively; The preheating sub-pipeline includes multiple groups of condensers corresponding to the purification towers and arranged in parallel, and a condenser regulating valve is provided at the inlet of the condenser; The main cooling sub-pipeline includes multiple groups of evaporators corresponding to the purification towers and arranged in parallel, and an evaporator regulating valve is provided at the inlet of the evaporator; The outlet of the preheating sub-line is connected to the inlet of the main cooling sub-line through a control valve, and the outlet of the main cooling sub-line is connected to the inlet of the preheating sub-line through a supplementary cooling sub-line and a compressor connected in series.

[0006] Furthermore, the cooling sub-pipeline includes a cooling medium three-way valve, a heat exchanger, a pump, a cooling tower and a cooling supplement regulating valve. The heat exchanger includes a high-temperature side of the heat exchanger and a low-temperature side of the heat exchanger. The inlet of the cooling medium three-way valve is connected to the evaporator, and the two outlets are respectively connected to the input end of the high-temperature side of the heat exchanger and the compressor. The output end of the high-temperature side of the heat exchanger is connected to the compressor, the input end of the low-temperature side of the heat exchanger is connected to the cooling supplement regulating valve, and the output end of the low-temperature side of the heat exchanger is connected to the pump. The cooling tower is arranged between the cooling supplement regulating valve and the pump.

[0007] Furthermore, the structures of the condenser, evaporator and heat exchanger are plate type or shell and tube type, and the condenser, evaporator and heat exchanger are filled with heat exchange medium, which is any one of liquid working fluid and phase change heat storage material.

[0008] Furthermore, the control valve is an expansion valve or a throttle valve.

[0009] Furthermore, the gas inlet sub-pipeline is provided with a crude gas three-way valve corresponding to a single purification tower, and the gas outlet sub-pipeline is provided with a pure gas three-way valve corresponding to a single purification tower.

[0010] Furthermore, at the same time, the three purification towers are respectively in a working state, a regeneration state or an adsorption state, and the states of the three purification towers are cyclically switched with each other.

[0011] Furthermore, the flow direction of the heat exchange medium in the condenser forms a countercurrent arrangement with the flow direction of the gas.

[0012] Based on the above system, the present invention also provides a gas purification method using cold and hot cycles, comprising the following steps: During the heating process, the heat exchange medium delivered by the compressor flows through the condenser regulating valve and condenser in sequence. The heat exchange medium condenses and releases heat through the condenser, transferring the heat to the gas flowing through the purification tower, causing the gas temperature to rise. At this time, the heat exchange medium changes from gas to liquid; In the first refrigeration process, the heat exchange medium in the condenser exchanges heat with the countercurrent gas and then enters the control valve. The heat exchange medium becomes a gas-liquid mixture and then enters the evaporator through the evaporator regulating valve. The heat exchange medium evaporates and becomes gas, absorbing a large amount of heat, and cools the high-temperature gas in the corresponding purification tower. After being cooled through the cooling sub-pipeline, the heat exchange medium enters the compressor and repeats the above heating process and the first cooling process.

[0013] Furthermore, it also includes a second refrigeration process, in which the heat exchange medium in the evaporator passes through the heat exchange medium pipe and flows through the cooling medium three-way valve, a part of which flows directly back to the compressor, and the other part is diverted to the high-temperature side of the heat exchanger. Through heat exchange with the low-temperature side of the heat exchanger, the heat exchange medium is cooled and then flows back to the compressor.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) Synchronous supply of cold and heat sources: By coupling the preheating sub-pipeline (condenser heat release) and the main cooling sub-pipeline (evaporator heat absorption) through the heat exchange medium circulation pipeline, the purification tower can be supplied with energy for the regeneration cycle and the cooling cycle at the same time, solving the problem that traditional technology cannot meet the cold and heat requirements synchronously; (2) Energy consumption is greatly reduced: The cold and hot loads in the regeneration cycle and cooling cycle are recycled through the Rankine cycle through the heat exchange medium, thereby realizing the recycling of cold and hot loads. The energy efficiency ratio APF can reach 2-5 or above. Only power P is required to achieve the heat APF*P required for gas heating during the gas purification process, thereby greatly reducing energy consumption; and by synchronously supplying heat source Q1 and cold source Q2, and energy consumption = [MAX(Q1, Q2)+Q'] / APF+P 压缩机 , where Q'=|Q1-Q2|, is much lower than the energy consumption of traditional electric heating to provide heat source Q1 and the auxiliary system to provide cooling source Q2. This solves the problem of excessive energy consumption of electric heating in traditional gas purification processes and significantly reduces electricity costs. While reducing energy consumption, it also reduces the flow rate of regenerated gas and the amount of cooling water for auxiliary equipment. (3) Reduced investment costs: Compared with traditional gas purification systems, the present invention can reduce some independent electric heating equipment and public auxiliary cooling systems such as chillers, and reuse waste heat through cooling sub-pipelines, thereby reducing the amount of circulating water and the scale of supporting equipment, thereby reducing the overall investment cost; (4) High multi-tower circulation efficiency: Multiple purification towers can realize the rotation of working / regeneration / adsorption state, and the countercurrent heat exchange design improves the heat transfer efficiency; the valve control can flexibly distribute the hot and cold flows to adapt to the gas volatility requirements, with strong control flexibility and high circulation efficiency; (5) Strong versatility: It is suitable for the purification of various gases such as hydrogen, nitrogen, and oxygen. It is especially suitable for high-energy consumption scenarios such as water electrolysis to produce hydrogen. It has strong versatility and high promotion value.

[0015] In summary, the present invention takes heat pump technology as its core and, through combined heat and cold supply and recycling, solves the problems of traditional gas purification systems, such as large overall equipment investment, large circulating water volume, high energy consumption, and inability to simultaneously heat and cool drying towers in different cycle states. It achieves dual optimization of energy consumption and equipment costs, breaking through the energy efficiency bottleneck of traditional purification systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the gas purification device of the present invention; Reference numerals: 1, compressor; 11, first condenser regulating valve; 2, control valve; 21, second condenser regulating valve; 31, third condenser regulating valve; 12, first condenser; 22, second condenser; 32, third condenser; 13, first evaporator regulating valve; 23, second evaporator regulating valve; 33, third evaporator regulating valve; 14, first evaporator; 24, second evaporator; 34, third evaporator; 40, heat exchanger; 401, low-temperature side of heat exchanger; 402, high-temperature side of heat exchanger; 41, cooling medium three-way valve; 50, cooling tower; 51, pump; 52. Supplementary cooling regulating valve; 61. First crude hydrogen three-way valve; 62. Second crude hydrogen three-way valve; 63. Third crude hydrogen three-way valve; 71. First pure hydrogen three-way valve; 72. Second pure hydrogen three-way valve; 73. Third pure hydrogen three-way valve; 74. Pure hydrogen regulating valve; 81. First purification tower; 82. Second purification tower; 83. Third purification tower; 91. Gas inlet sub-pipeline; 92. Gas outlet sub-pipeline. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0018] A gas purification system with hot and cold cycle utilization, such as Figure 1 As shown, the purified gas in this embodiment is hydrogen. The gas purification system is equipped with multiple purification towers, as well as heat exchange medium circulation pipelines and gas pipelines flowing through the purification towers. The heat exchange medium circulation pipelines include: a preheating sub-pipeline, a main cooling sub-pipeline, and a supplemental cooling sub-pipeline; the gas pipelines include: an inlet sub-pipeline 91 and an outlet sub-pipeline 92. The preheating sub-pipeline and the main cooling sub-pipeline flow through the upper and lower parts of the purification towers, respectively.

[0019] Specifically, the preheating sub-pipeline is equipped with multiple sets of condensers, each corresponding to a purification tower and connected in parallel. Condenser regulating valves are installed at the condenser inlets, allowing the heat exchange medium in the preheating sub-pipeline to flow into the condensers through the condenser regulating valves. More specifically, in this embodiment, the purification towers include: a first purification tower 81, a second purification tower 82, and a third purification tower 83; the condenser regulating valves include: a first condenser regulating valve 11, a second condenser regulating valve 21, and a third condenser regulating valve 31; and the condensers include: a first condenser 12, a second condenser 22, and a third condenser 32. The first purification tower 81 is equipped with the first condenser regulating valve 11 and the first condenser 12; the second purification tower 82 is equipped with the second condenser regulating valve 21 and the second condenser 22; and the third purification tower 83 is equipped with the third condenser regulating valve 31 and the third condenser 32. By setting the condenser regulating valve, the heat exchange medium on the preheating sub-pipeline can also enter the second purification tower 82 directly without passing through the first purification tower 81, or directly enter the third purification tower 83 without passing through the first purification tower 81 and the second purification tower 82.

[0020] Specifically, multiple groups of evaporators are provided on the main cooling sub-pipeline, corresponding one-to-one to the purification towers and connected in parallel. Evaporator regulating valves are provided at the inlet of the evaporators, and the heat exchange medium on the main cooling sub-pipeline flows into the evaporators through the evaporator regulating valves. More specifically, in this embodiment, the evaporator regulating valves include: evaporator regulating valve 13, second evaporator regulating valve 23, and third evaporator regulating valve 33, and the evaporators include: first evaporator 14, second evaporator 24, and third evaporator 34. The first evaporator regulating valve 13 and the first evaporator 14 are provided at the lower portion of the first purification tower 81; the second evaporator regulating valve 23 and the second evaporator 24 are provided at the lower portion of the second purification tower 82; and the third evaporator regulating valve 33 and the third evaporator 34 are provided at the lower portion of the third purification tower 83. Depending on the circumstances, the heat exchange medium on the main cooling sub-pipeline can also directly enter the second purification tower 82 without passing through the third purification tower 83, or directly enter the first purification tower 81 without passing through the third purification tower 83 and the second purification tower 82. In addition, the outlet of the preheating sub-pipeline is connected to the inlet of the main cooling sub-pipeline through the control valve 2, and the outlet of the main cooling sub-pipeline is connected to the inlet of the preheating sub-pipeline through the supplementary cooling sub-pipeline and the compressor 1 connected in series.

[0021] In this embodiment, the cooling sub-pipeline includes a cooling medium three-way valve 41, a heat exchanger 40, a cooling tower 50, a pump 51 and a cooling supplement regulating valve 52. The heat exchanger 40 includes a high-temperature side 402 of the heat exchanger and a low-temperature side 401 of the heat exchanger. The inlet of the cooling medium three-way valve 41 is connected to the evaporator 40, and the two outlets of the cooling medium three-way valve 41 are respectively connected to the input end of the high-temperature side 402 of the heat exchanger and the compressor 1. The ratio of the heat exchange medium entering the high-temperature side 402 of the heat exchanger and the compressor 1 is adjusted according to actual conditions. The output end of the high-temperature side 402 of the heat exchanger is connected to the compressor 1, the input end of the low-temperature side 401 of the heat exchanger is connected to the cooling supplement regulating valve 52, and the output end of the low-temperature side 401 of the heat exchanger is connected to the pump 51. The cooling tower 50 is arranged between the cooling supplement regulating valve 52 and the pump 51.

[0022] In this embodiment, the condenser, evaporator, and heat exchanger 40 are plate-type or shell-and-tube structures. They are filled with a heat exchange medium, which can be either a liquid working fluid or a phase-change thermal storage material. The heat pump sub-pipeline is used to transport the heat exchange medium. The heat pump sub-pipeline is made of copper tubing, while the hydrogen delivery pipeline is made of S312, a type of nickel-plated steel. In this embodiment, the control valve 2 is an expansion valve or a throttle valve, which converts part of the heat exchange medium from liquid to gas, thereby converting it into a gas-liquid mixed state.

[0023] In this embodiment, a crude gas three-way valve corresponding to each purification tower is installed on the gas inlet sub-pipeline 91, and a pure gas three-way valve corresponding to each purification tower is installed on the gas outlet sub-pipeline 92. The crude gas three-way valves include a first crude hydrogen three-way valve 61, a second crude hydrogen three-way valve 62, and a third crude hydrogen three-way valve 63; the pure gas three-way valves include a first pure hydrogen three-way valve 71, a second pure hydrogen three-way valve 72, and a third pure hydrogen three-way valve 73. The first purification tower 81 is provided with the first crude hydrogen three-way valve 61 and the first pure hydrogen three-way valve 71 at the top and bottom, respectively; the second purification tower 82 is provided with the second crude hydrogen three-way valve 62 and the second pure hydrogen three-way valve 72 at the top and bottom, respectively; and the third purification tower 83 is provided with the third crude hydrogen three-way valve 63 and the third pure hydrogen three-way valve 73 at the top and bottom, respectively. The crude gas three-way valves are used to adjust the proportion of hydrogen entering each purification tower, and the pure gas three-way valves are used to adjust the proportion of hydrogen flowing out of each purification tower.

[0024] In this embodiment, at the same time, the multiple purification towers are respectively in the working state, the regeneration state or the adsorption state, and the states of the multiple purification towers are cyclically switched with each other.

[0025] In this embodiment, the flow direction of the heat exchange medium in the condenser forms a countercurrent arrangement with the flow direction of the gas, which results in a better heat exchange effect.

[0026] Based on the above system, a gas purification method using cold and hot cycles is provided, comprising the following steps: During the heating process, the heat exchange medium delivered by compressor 1 flows through the condenser regulating valve and condenser in sequence. The heat exchange medium condenses and releases heat through the condenser, transferring the heat to the hydrogen flowing through the purification tower, raising the hydrogen temperature. At this time, the heat exchange medium changes from gas to liquid. In the first refrigeration process, the heat exchange medium in the condenser exchanges heat with the countercurrent gas and then enters the control valve 2. The heat exchange medium becomes a gas-liquid mixture and then enters the evaporator through the evaporator regulating valve. The heat exchange medium evaporates and becomes gas, absorbing a large amount of heat, and cools the high-temperature gas in the corresponding purification tower. After being cooled through the cooling sub-pipeline, the heat exchange medium enters the compressor and repeats the above heating process and the first cooling process.

[0027] The gas purification method of the present invention recycles the cold and heat loads in the regeneration cycle and the cooling cycle through the heat exchange medium using the Rankine cycle, which can simultaneously supply the heat source Q1 and the cold source Q2, and the energy consumption = [MAX (Q1, Q2) + Q'] / APF + P 压缩机 , where Q'=|Q1-Q2|, i.e., Q' is the absolute value of the difference between Q1 and Q2, which is much lower than the energy consumption of traditional electric heating providing heat source Q1 and public auxiliary system providing cold source Q2, respectively. While reducing energy consumption, it also reduces the flow rate of regenerated gas and the amount of cooling water for public auxiliary equipment.

[0028] The gas purification method of this embodiment also includes a second refrigeration process. The heat exchange medium in the evaporator passes through the heat exchange medium pipe and flows through the cooling medium three-way valve 41. A portion of it flows directly back to the compressor 1, and the other portion is diverted to the high-temperature side 402 of the heat exchanger. Through heat exchange with the low-temperature side 401 of the heat exchanger, the heat exchange medium is cooled and then flows back to the compressor 1.

[0029] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings and specific embodiments. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

Claims

1. A gas purification system utilizing cold and hot cycles, characterized in that: include: It includes a plurality of purification towers, and heat exchange medium circulation pipelines and gas pipelines flowing through the plurality of purification towers; The heat exchange medium circulation pipeline includes a preheating sub-pipeline, a main cooling sub-pipeline and a supplementary cooling sub-pipeline; The gas pipeline includes an inlet sub-pipeline and an outlet sub-pipeline; The preheating sub-pipeline and the main cooling sub-pipeline flow through the upper part and the lower part of the purification tower respectively; The preheating sub-pipeline includes multiple groups of condensers corresponding to the purification towers and arranged in parallel, and a condenser regulating valve is provided at the inlet of the condenser; The main cooling sub-pipeline includes multiple groups of evaporators corresponding to the purification towers and arranged in parallel, and an evaporator regulating valve is provided at the inlet of the evaporator; The outlet of the preheating sub-line is connected to the inlet of the main cooling sub-line through a control valve, and the outlet of the main cooling sub-line is connected to the inlet of the preheating sub-line through a supplementary cooling sub-line and a compressor connected in series.

2. A gas purification system for hot and cold cycle utilization according to claim 1, characterized in that: The cooling sub-pipeline includes a cooling medium three-way valve, a heat exchanger, a pump, a cooling tower and a cooling supplement regulating valve. The heat exchanger includes a high-temperature side of the heat exchanger and a low-temperature side of the heat exchanger. The inlet of the cooling medium three-way valve is connected to the evaporator, and the two outlets of the cooling medium three-way valve are respectively connected to the input end of the high-temperature side of the heat exchanger and the compressor. The output end of the high-temperature side of the heat exchanger is connected to the compressor, the input end of the low-temperature side of the heat exchanger is connected to the cooling supplement regulating valve, and the output end of the low-temperature side of the heat exchanger is connected to the pump. The cooling tower is arranged between the cooling supplement regulating valve and the pump.

3. The gas purification system for hot and cold cycle utilization according to claim 2, characterized in that: The structures of the condenser, evaporator and heat exchanger are plate type or shell and tube type. The condenser, evaporator and heat exchanger are filled with heat exchange medium, which is any one of liquid working fluid and phase change heat storage material.

4. The gas purification system for hot and cold cycle utilization according to claim 1, characterized in that: The control valve is an expansion valve or a throttle valve.

5. The gas purification system for cold and hot cycle utilization according to claim 1, characterized in that: The gas inlet sub-pipeline is provided with a crude gas three-way valve corresponding to a single purification tower, and the gas outlet sub-pipeline is provided with a pure gas three-way valve corresponding to a single purification tower.

6. The gas purification system for hot and cold cycle utilization according to claim 1, characterized in that: The purification tower includes a first purification tower, a second purification tower and a third purification tower, wherein the first purification tower, the second purification tower and the third purification tower all have a working state, a regeneration state and an adsorption state that are cyclically switched with each other; At the same time, the three purification towers are respectively in the working state, the regeneration state or the adsorption state, and the states of the three purification towers are cyclically switched with each other; In the working state, the second purification tower is a regeneration tower, the first purification tower is a first drying tower, and the third purification tower is a second drying tower; In the regeneration state, the second purification tower is the first drying tower, the first purification tower is the second drying tower, and the third purification tower is the regeneration tower; In the adsorption state, the second purification tower is a second drying tower, the first purification tower is a regeneration tower, and the second purification tower is a first drying tower.

7. The gas purification system for cold and hot cycle utilization according to claim 1, characterized in that: The flow direction of the heat exchange medium in the condenser forms a counter-flow arrangement with the flow direction of the gas.

8. A gas purification method using cold and hot cycles based on the system according to any one of claims 1 to 7, characterized in that: The following steps are involved: During the heating process, the heat exchange medium delivered by the compressor flows through the condenser regulating valve and condenser in sequence. The heat exchange medium condenses and releases heat through the condenser, transferring the heat to the gas flowing through the purification tower, causing the gas temperature to rise. At this time, the heat exchange medium changes from gas to liquid; In the first refrigeration process, the heat exchange medium in the condenser exchanges heat with the countercurrent gas and then enters the control valve. The heat exchange medium becomes a gas-liquid mixture and then enters the evaporator through the evaporator regulating valve. The heat exchange medium evaporates and becomes gas, absorbing a large amount of heat, and cools the high-temperature gas in the corresponding purification tower. After being cooled through the cooling sub-pipeline, the heat exchange medium enters the compressor and repeats the above heating process and the first cooling process.

9. The method for purifying gas by cold and hot cycle utilization according to claim 8, characterized in that: It also includes a second refrigeration process, in which the heat exchange medium in the evaporator passes through the heat exchange medium pipe and flows through the cooling medium three-way valve. A part of it flows directly back to the compressor, and the other part is diverted to the high-temperature side of the heat exchanger. Through heat exchange with the low-temperature side of the heat exchanger, the heat exchange medium is cooled and then flows back to the compressor.

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