An oxygen recovery device and method by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas

Abstract

The present invention discloses a method for oxygen recovery by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas, which comprises the following steps: condensing and dust-removing the normal-pressure high-humidity oxygen-rich flue gas, compressing the flue gas, pre-cooling, purifying and drying, and preparing oxygen by low-temperature rectification. The waste gas generated in the low-temperature rectification step is used as a refrigeration medium and recycled in the low-temperature rectification step. Aiming at the technical problem that the oxygen-rich tail gas in the lithium battery production process is directly discharged, resulting in waste of resources, the present invention provides a device and method for oxygen recovery by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas, which can purify, recover and reuse the oxygen in the oxygen-rich flue gas with approximate normal pressure in the reaction kettle, and improve the utilization rate of resources.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation, and particularly relates to a cryogenic oxygen recovery device and method for oxygen-rich flue gas with normal pressure and high humidity. Background Art

[0002] A lithium-ion battery refers to a battery composed of a lithium alloy metal oxide as the positive electrode material, graphite as the negative electrode material, and a non-aqueous electrolyte. It has the characteristics of environmental protection, high performance, and long operating time, and has become one of the key points in the development of the battery industry. Among them, in the production reactor of the positive electrode material of lithium batteries, a large amount of oxygen-rich flue gas with high temperature, high humidity, and near normal pressure will inevitably be generated. If these oxygen-rich tail gases are directly discharged after treatment, it will cause a waste of a large amount of oxygen, resulting in a waste of overall energy consumption and an increase in production costs. Summary of the Invention

[0003] 1. Technical Problems to be Solved by the Invention

[0004] In view of the technical problem of direct discharge of oxygen-rich tail gas during the production of lithium batteries, resulting in waste of resources, the present invention provides a cryogenic oxygen recovery device and method for oxygen-rich flue gas with normal pressure and high humidity, which can purify and recycle oxygen from the oxygen-rich flue gas with near normal pressure in the reactor, and improve the utilization rate of resources.

[0005] 2. Technical Solutions

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] A cryogenic oxygen recovery device for oxygen-rich flue gas with normal pressure and high humidity includes a flue gas pipeline, and a condensation and dust removal module, a recovered flue gas compression module, a pre-cooling, purification and drying module, and a low-temperature rectification module are sequentially arranged on the flue gas pipeline. The low-temperature rectification module includes a first heat exchanger, a gas-liquid separation tank, and a rectification tower that are sequentially arranged on the flue gas pipeline. An oxygen delivery pipeline and a nitrogen circulation pipeline are connected to the rectification tower. An exhaust gas outlet and a nitrogen circulation inlet connected to the nitrogen circulation pipeline are provided on the rectification tower. A nitrogen circulation refrigeration module is provided on the nitrogen circulation pipeline. The oxygen delivery pipeline and the nitrogen circulation pipeline pass through the heat absorption pipeline of the first heat exchanger.

[0008] Optionally, the nitrogen circulation refrigeration module includes a second heat exchanger, a circulating nitrogen compressor, a circulating nitrogen compressor final stage cooler, and a rectification tower evaporator. The nitrogen circulation pipeline sequentially passes through the heat absorption pipeline of the second heat exchanger, the heat absorption pipeline of the first heat exchanger, the circulating nitrogen compressor, the circulating nitrogen compressor final stage cooler, the heat supply pipeline of the second heat exchanger, the rectification tower evaporator, and the heat supply pipeline of the second heat exchanger, and then is connected to the nitrogen circulation inlet of the rectification tower.

[0009] Optionally, the nitrogen cycle refrigeration module further includes a refrigeration pipeline and a circulating nitrogen expander disposed on the refrigeration pipeline. After a part of the medium in the nitrogen cycle pipeline passes through the circulating nitrogen compressor and the final-stage cooler, it passes through the refrigeration pipeline and then passes through the circulating nitrogen compressor and the final-stage cooler of the circulating nitrogen compressor again.

[0010] Optionally, the nitrogen cycle refrigeration module further includes a liquid nitrogen replenishment pipeline communicated with the rectification tower.

[0011] Optionally, it further includes a cold box, and the first heat exchanger, the gas-liquid separation tank, the rectification tower, the second heat exchanger, the circulating nitrogen compressor, the final-stage cooler of the circulating nitrogen compressor, the rectification tower evaporator, and the circulating nitrogen expander are all installed in the cold box.

[0012] Optionally, the condensation and dust removal module includes a temperature and humidity reducer, a dust removal filter, and a blower sequentially arranged on the flue gas pipeline.

[0013] Optionally, the recovered flue gas compression module includes a flue gas compressor, a final-stage cooler of the flue gas compressor, and a first buffer tank sequentially arranged on the flue gas pipeline.

[0014] Optionally, the precooling, purification and drying module includes a refrigerator, a second buffer tank, a molecular sieve adsorption twin tower sequentially arranged on the flue gas pipeline, and a regeneration electric heater connected to the molecular sieve adsorption twin tower.

[0015] Optionally, the regeneration gas in the molecular sieve adsorption twin tower is the waste gas generated in the low-temperature rectification module.

[0016] A method for recovering oxygen from atmospheric-pressure high-humidity oxygen-rich flue gas by cryogenic method includes the following steps: condensing and removing dust, compressing the flue gas, precooling, purifying and drying, and low-temperature rectification of the atmospheric-pressure high-humidity oxygen-rich flue gas to obtain oxygen, and the waste gas generated in the low-temperature rectification step is used as a refrigeration medium and recycled in the low-temperature rectification step.

[0017] 3. Beneficial effects

[0018] Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects:

[0019] (1) The oxygen recovery device by cryogenic method for near-atmospheric-pressure high-humidity oxygen-rich flue gas can purify and recycle oxygen from the oxygen-rich flue gas with near-atmospheric pressure in the reaction kettle. A condensation and dust removal module is adopted at the front end, which can effectively remove micron-level metal oxide dust in the recycled flue gas, and at the same time condense and remove a part of water to reduce the activity of oxygen molecules and ensure the safe operation of downstream equipment; the low-temperature rectification method is used to separate and purify the oxygen in the recycled flue gas, and the structured packing tower technology representing the most advanced level of current air separation technology is adopted, which can achieve high oxygen extraction rate (purity can reach 99.6% and above), low overall energy consumption, safe and reliable operation, etc.; the waste gas in the rectification process is used as the refrigeration medium for circulating rectification, reducing the consumption of nitrogen by the device, and the process organization is simple; the oxygen recovery device by cryogenic method for near-atmospheric-pressure high-humidity oxygen-rich flue gas makes full use of the oxygen-rich flue gas discharged from the lithium battery production reaction kettle, with an advanced process, mature technology, safe and reliable, convenient to operate, reasonable and economical equipment configuration, high oxygen recovery and extraction rate, and the purity of the recovered pure oxygen can reach 99.6% and above, effectively saving the production energy consumption of the system and reducing the system cost. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of an oxygen recovery device and method by cryogenic method for near-atmospheric-pressure high-humidity oxygen-rich flue gas proposed in an embodiment of the present invention;

[0021] 1. Flue gas pipeline; 2. First heat exchanger; 3. Gas-liquid separation tank; 4. Rectification tower; 4a. Waste gas outlet; 4b. Nitrogen circulation inlet; 5. Oxygen delivery pipeline; 6. Nitrogen circulation pipeline; 7. Second heat exchanger; 8. Circulating nitrogen compressor; 9. Final stage cooler of the circulating nitrogen compressor; 10. Evaporator of the rectification tower; 11. Refrigeration pipeline; 12. Circulating nitrogen expander; 13. Liquid nitrogen supplement pipeline; 14. Cold box; 15. Temperature and humidity reducer; 16. Dust removal filter; 17. Fan; 18. Flue gas compressor; 19. Final stage cooler of the flue gas compressor; 20. First buffer tank; 21. Refrigerator; 22. Second buffer tank; 23. Molecular sieve adsorption twin towers; 24. Regenerative electric heater. Detailed Embodiments

[0022] To further understand the content of the present invention, it will be described in detail in combination with the attached Figure 1 drawings and embodiments.

[0023] Embodiment 1

[0024] In combination with the attached Figure 1, An oxygen recovery device for cryogenic method of normal-pressure high-humidity oxygen-rich flue gas in this embodiment includes a flue gas pipeline 1, and a condensation and dust removal module, a recovered flue gas compression module, a pre-cooling, purification and drying module, and a low-temperature rectification module sequentially arranged on the flue gas pipeline 1. One end of the flue gas pipeline 1 is used to collect the tail gas generated during the production process of lithium batteries. The low-temperature rectification module includes a first heat exchanger 2, a gas-liquid separation tank 3, and a rectification tower 4 sequentially arranged on the flue gas pipeline 1. The flue gas pipeline 1 passes through the heat release pipeline of the first heat exchanger 2. The rectification tower 4 is a packed tower. The oxygen-rich flue gas enters the rectification tower 4 for rectification and purification. In the rectification tower 4, the rising gas and the flowing-down liquid are in full contact. After mass transfer and heat transfer, pure liquid oxygen is obtained. An oxygen delivery pipeline 5 and a nitrogen circulation pipeline 6 are connected to the rectification tower 4. The oxygen delivery pipeline 5 is communicated with the bottom of the rectification tower 4 to cyclically feed the liquid oxygen at the bottom of the rectification tower 4 into the production reactor of the lithium battery positive electrode material. A liquid oxygen pump is provided on the oxygen delivery pipeline 5. An exhaust gas outlet 4a and a nitrogen circulation inlet 4b connected to the nitrogen circulation pipeline 6 are provided at the upper end of the rectification tower 4. A nitrogen circulation refrigeration module is provided on the nitrogen circulation pipeline 6. The oxygen delivery pipeline 5 and the nitrogen circulation pipeline 6 pass through the heat absorption pipeline of the first heat exchanger 2. Two heat absorption pipelines are provided on the first heat exchanger 2, which are respectively connected to the oxygen delivery pipeline 5 and the nitrogen circulation pipeline 6. The exhaust gas generated in the rectification tower 4 is used as a refrigeration medium to circulate in the low-temperature rectification module.

[0025] This oxygen recovery device for cryogenic method of normal-pressure high-humidity oxygen-rich flue gas can purify, recover and reuse the oxygen in the oxygen-rich flue gas with approximate normal pressure in the reactor. A condensation and dust removal module is adopted at the front end, which can effectively remove the micron-level metal oxide dust in the recovered flue gas, and at the same time condense and remove a part of water to reduce the activity of oxygen molecules and ensure the safe operation of downstream equipment; the low-temperature rectification method is used to separate and purify the oxygen in the recovered flue gas, and the structured packing tower technology representing the most advanced level of current air separation technology is adopted, which can achieve the characteristics of high oxygen extraction rate (purity can reach 99.6% and above), low overall energy consumption, safe and reliable operation, etc.; the exhaust gas in the rectification process is used as a refrigeration medium to circulate and rectify, reducing the consumption of nitrogen by the device, and the process organization is simple; this oxygen recovery device for cryogenic method of normal-pressure high-humidity oxygen-rich flue gas makes full use of the oxygen-rich flue gas discharged from the lithium battery production reactor, with an advanced process, mature technology, safe and reliable, convenient to operate, reasonable economic equipment configuration, high oxygen recovery and extraction rate, and the purity of the recovered pure oxygen can reach 99.6% and above (oxygen can be extracted during the exhaust gas circulation process), effectively saving the production energy consumption of the system and reducing the system cost.

[0026] As an alternative embodiment of the present invention, the nitrogen cycle refrigeration module includes a second heat exchanger 7, a circulating nitrogen compressor 8, a final stage cooler 9 of the circulating nitrogen compressor, and a rectification column evaporator 10. The rectification column evaporator 10 is installed inside the rectification column 4, and the rectification column evaporator 10 and the rectification column 4 are of an integral structure. The nitrogen cycle pipeline 6 sequentially passes through the heat absorption pipeline of the second heat exchanger 7, the heat absorption pipeline of the first heat exchanger 2, the circulating nitrogen compressor 8, the final stage cooler 9 of the circulating nitrogen compressor, the heat supply pipeline of the second heat exchanger 7, the rectification column evaporator 10, and the heat supply pipeline of the second heat exchanger 7, and then is connected to the nitrogen cycle inlet 4b of the rectification column 4. When the waste gas passes through the rectification column evaporator 10, it releases heat and promotes the gas in the rectification column 4 to flow from bottom to top. As power, in the second heat exchanger 7, the waste gas discharged from the rectification column 4 exchanges heat with the waste gas passing through the rectification column evaporator 10. The waste gas passing through the rectification column evaporator 10 is further cooled and then enters the rectification column 4. After the waste gas discharged from the rectification column 4 passes through the second heat exchanger 7, it absorbs heat and heats up again through the heat absorption pipeline of the first heat exchanger 2, and then is cooled by the circulating nitrogen compressor 8 and the final stage cooler 9 of the circulating nitrogen compressor. The cooled waste gas enters the heat supply pipeline of the first heat exchanger 2 to further release heat and cool down, and then passes through the rectification column evaporator 10 to exchange heat with the waste gas discharged from the rectification column 4 in the second heat exchanger 7.

[0027] As an alternative embodiment of the present invention, the nitrogen cycle refrigeration module further includes a refrigeration pipeline 11 and a circulating nitrogen expander 12 provided on the refrigeration pipeline 11. One end of the refrigeration pipeline 11 is connected to the heat supply pipeline in the first heat exchanger 2 that is connected to the nitrogen cycle pipeline 6, and the other end is connected to the pipeline of the nitrogen cycle pipeline 6 before it is connected to the heat absorption pipeline in the first heat exchanger 2. A part of the medium in the nitrogen cycle pipeline 6 passes through the circulating nitrogen compressor 8 and the final stage cooler 9, and then passes through the refrigeration pipeline 11 and passes through the circulating nitrogen compressor 8 and the final stage cooler 9 of the circulating nitrogen compressor again, so as to ensure that the flue gas temperature and waste gas temperature passing through the first heat exchanger 2 can meet the rectification requirements after heat exchange.

[0028] As an alternative embodiment of the present invention, the nitrogen cycle refrigeration module further includes a liquid nitrogen supplement pipeline 13 communicated with the rectification column 4. The liquid nitrogen supplement pipeline 13 can add liquid nitrogen to the rectification column 4 as a cold source. In practical applications, the circulating nitrogen expander 12 and the liquid nitrogen supplement pipeline 13 are two mutually replaceable solutions. When both are set at the same time, only when the refrigeration capacity is significantly insufficient will the combined method be adopted.

[0029] As an alternative embodiment of the present invention, it further includes a cold box 14. The first heat exchanger 2, gas-liquid separation tank 3, rectification column 4, second heat exchanger 7, recycle nitrogen compressor 8, final-stage cooler 9 of the recycle nitrogen compressor, rectification column evaporator 10, and recycle nitrogen expander 12 are all installed inside the cold box 14. A cold box is a set of highly efficient and adiabatic cold-preserving low-temperature heat exchange devices, which is often used in cryogenic separation processes. For example, in the cryogenic separation process of petroleum pyrolysis gas, a cold box operating at about -100 to -140 °C is used. It consists of a highly efficient plate heat exchanger with a compact structure and a gas-liquid separator. Since low temperature is extremely prone to heat dissipation and extremely strict adiabatic cold preservation is required, the heat exchanger and the separator are both packaged in a box-shaped object with heat-insulating materials, which is called a cold box.

[0030] As an alternative embodiment of the present invention, the condensation and dust removal module includes a temperature and humidity reducer 15, a dust removal filter 16, and a blower 17 sequentially arranged on the flue gas pipeline 1. Its main function is to pre-treat the flue gas and reduce the activity of oxygen molecules.

[0031] As an alternative embodiment of the present invention, the recovered flue gas compression module includes a flue gas compressor 18, a final-stage cooler 19 of the flue gas compressor, and a first buffer tank 20 sequentially arranged on the flue gas pipeline 1. The oxygen-rich flue gas is separated into gas and liquid in the first buffer tank 20. Its main function is to compress and cool the flue gas, and the condensed water separated into gas and liquid in the first buffer tank 20 is discharged through a pipeline.

[0032] As an alternative embodiment of the present invention, the pre-cooling, purification, and drying module includes a refrigerator 21, a second buffer tank 22, a molecular sieve adsorption twin tower 23, and a regeneration electric heater 24 connected to the molecular sieve adsorption twin tower 23 sequentially arranged on the flue gas pipeline 1. The oxygen-rich flue gas is separated into gas and liquid in the second buffer tank 22. The molecular sieve adsorption twin tower 23 is filled with alumina and high-efficiency molecular sieves. The flue gas after purification and drying is sent to the next unit. When one tower of the molecular sieve adsorption twin tower 23 is adsorbing, the other tower is desorbing and regenerating. The switching period is 8 hours (the single-tower working time is 4 hours), and it is automatically switched regularly by the control system. The regeneration gas in the molecular sieve adsorption twin tower 23 is the waste gas generated in the low-temperature rectification module, and the molecular sieve is regenerated by steam or the regeneration electric heater 24.

[0033] As an alternative embodiment of the present invention, the heat exchangers in the first heat exchanger 2, the second heat exchanger 7, and the rectification column evaporator 10 in this embodiment are all vacuum brazed plate-fin heat exchangers to ensure the heat exchange effect and heat exchange efficiency.

[0034] Embodiment Two

[0035] A method for oxygen recovery from normal-pressure high-humidity oxygen-rich flue gas by cryogenic method, comprising the following steps: condensing and dust-removing the normal-pressure high-humidity oxygen-rich flue gas, compressing the flue gas, pre-cooling, purifying and drying it, and preparing oxygen by low-temperature rectification. The waste gas generated in the low-temperature rectification step is used as a refrigeration medium and recycled in the low-temperature rectification step.

[0036] This method for oxygen recovery from normal-pressure high-humidity oxygen-rich flue gas by cryogenic method is used to purify, recover and reuse the oxygen in the oxygen-rich flue gas with approximate normal pressure in the reaction kettle. Through the condensing and dust-removing step, the metal oxide dust in the micron level in the recovered flue gas can be effectively removed, and at the same time, a part of water is condensed and removed to reduce the activity of oxygen molecules and ensure the safe operation of downstream equipment. The low-temperature rectification method is adopted to separate and purify the oxygen in the recovered flue gas. By using the structured packing column technology representing the most advanced level of current air separation technology, the characteristics of high oxygen extraction rate (up to 99.6% and above), low overall energy consumption, safe and reliable operation, etc. can be achieved. The waste gas in the rectification process is used as a refrigeration medium for recycling rectification, reducing the consumption of nitrogen by the device, and the process organization is simple. This device for oxygen recovery from normal-pressure high-humidity oxygen-rich flue gas by cryogenic method makes full use of the oxygen-rich flue gas discharged from the reaction kettle in lithium battery production. The process is advanced, the technology is mature, safe and reliable, easy to operate, the equipment configuration is economically reasonable, the oxygen recovery and extraction rate is high, and the purity of the recovered pure oxygen can reach 99.6% and above (oxygen can be extracted during the waste gas recycling process), effectively saving the production energy consumption of the system and reducing the system cost.

[0037] The above schematically describes the present invention and its embodiments, and this description is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and design similar structural modes and embodiments without creative work without departing from the spirit of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. An oxygen recovery device by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas, characterized in that: it includes a flue gas pipeline, and a condensation and dust removal module, a recovered flue gas compression module, a precooling, purification and drying module, and a low-temperature rectification module that are sequentially arranged on the flue gas pipeline. The low-temperature rectification module includes a first heat exchanger, a gas-liquid separation tank, and a rectification tower that are sequentially arranged on the flue gas pipeline. An oxygen delivery pipeline and a nitrogen circulation pipeline are connected to the rectification tower. An exhaust gas outlet and a nitrogen circulation inlet connected to the nitrogen circulation pipeline are provided on the rectification tower. A nitrogen circulation refrigeration module is provided on the nitrogen circulation pipeline. The oxygen delivery pipeline and the nitrogen circulation pipeline pass through the heat absorption pipeline of the first heat exchanger; the nitrogen circulation refrigeration module includes a second heat exchanger, a circulating nitrogen compressor, a final-stage cooler of the circulating nitrogen compressor, and a rectification tower evaporator. The nitrogen circulation pipeline sequentially passes through the heat absorption pipeline of the second heat exchanger, the heat absorption pipeline of the first heat exchanger, the circulating nitrogen compressor, the final-stage cooler of the circulating nitrogen compressor, the heat supply pipeline of the second heat exchanger, the rectification tower evaporator, and the heat supply pipeline of the second heat exchanger, and then is connected to the nitrogen circulation inlet of the rectification tower; the nitrogen circulation refrigeration module further includes a refrigeration pipeline, and a circulating nitrogen expander provided on the refrigeration pipeline. A part of the medium in the nitrogen circulation pipeline passes through the circulating nitrogen compressor and the final-stage cooler, and then passes through the refrigeration pipeline and passes through the circulating nitrogen compressor and the final-stage cooler of the circulating nitrogen compressor again.

2. The oxygen recovery device by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas according to claim 1, characterized in that: the nitrogen circulation refrigeration module further includes a liquid nitrogen replenishment pipeline communicated with the rectification tower.

3. The oxygen recovery device by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas according to any one of claims 1-2, characterized in that: it further includes a cold box, and the first heat exchanger, the gas-liquid separation tank, the rectification tower, the second heat exchanger, the circulating nitrogen compressor, the final-stage cooler of the circulating nitrogen compressor, the rectification tower evaporator, and the circulating nitrogen expander are all installed in the cold box.

4. The oxygen recovery device by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas according to claim 3, characterized in that: the condensation and dust removal module includes a temperature and humidity reducer, a dust removal filter, and a blower that are sequentially arranged on the flue gas pipeline.

5. The oxygen recovery device by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas according to claim 3, characterized in that: the recovered flue gas compression module includes a flue gas compressor, a final-stage cooler of the flue gas compressor, and a first buffer tank that are sequentially arranged on the flue gas pipeline.

6. The oxygen recovery device by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas according to claim 3, characterized in that: the precooling, purification and drying module includes a freezer, a second buffer tank, a molecular sieve adsorption twin tower, and a regeneration electric heater connected to the molecular sieve adsorption twin tower that are sequentially arranged on the flue gas pipeline.

7. The oxygen recovery device by cryogenic method for normal-pressure high-humidity oxygen-rich flue gas according to claim 6, characterized in that: the regeneration gas in the molecular sieve adsorption twin tower is the waste gas generated in the low-temperature rectification module.

8. A method for oxygen recovery from deep cooling of atmospheric-pressure high-humidity oxygen-rich flue gas, using the device for oxygen recovery from deep cooling of atmospheric-pressure high-humidity oxygen-rich flue gas according to any one of claims 1-7. It is characterized in that: It includes the following steps: condensing and dust-removing the atmospheric-pressure high-humidity oxygen-rich flue gas, compressing the flue gas, pre-cooling, purifying and drying it, and preparing oxygen through low-temperature rectification. The waste gas generated in the low-temperature rectification step is used as a refrigeration medium and recycled in the low-temperature rectification step.

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