Double-tower rectification air separation system

Abstract

The invention relates to a double-tower rectification air separation system, which comprises: an energy storage unit, air is pressurized by a first compression device to generate heat, and the heat is taken away by a first cooling device to provide heat for a heating device, air pressurized and cooled by the first compression device and the first cooling device is cooled by the second cooling device and further cooled by the second expansion machine to generate a liquid phase which enters the gas-liquid separation device, and a liquid phase outlet of the gas-liquid separation device is connected with the heating device and the power generation device; a gas phase outlet of the gas-liquid separation device is connected with an inlet of a first flow divider, one outlet of the first flow divider is connected with the lower tower through a first heat exchanger, the other outlet of the first flow divider is connected with the upper tower through the first heat exchanger and a first expansion machine in sequence, and a liquid phase outlet of the lower tower is connected with the upper tower through a second heat exchanger. The energy storage unit is coupled with the air separation unit, and resources are fully utilized.

Description

Technical Field

[0001] The present disclosure relates to the technical field of air separation, and in particular, to a double-tower distillation air separation system. Background Art

[0002] Compressed air energy storage technology is to liquefy compressed air after cooling, throttling or expansion, which can greatly increase the air density, reduce the gas storage volume, and thus increase the energy storage density. The principle of the air cryogenic separation method relies on the difference in boiling points of various components in the air at different temperatures. This physical property allows these components to be effectively separated through a series of process steps. This method has broad application prospects in industrial production.

[0003] In the related art, compressed air energy storage and air cryogenic separation are both separately configured, which cannot fully utilize resources and will result in waste of resources. Summary of the invention

[0004] The purpose of the present disclosure is to provide a double-tower distillation air separation system, which can solve the above-mentioned technical problems.

[0005] In order to achieve the above-mentioned object, the present disclosure provides a double-tower distillation air separation system, comprising: an energy storage unit, comprising a gas-liquid separation device, a first compression device, a first cooling device, a second cooling device, a second expander, a heating device and a power generation device, wherein air is pressurized by the first compression device to generate heat, and the heat is taken away by the first cooling device to provide heat for the heating device, and the air pressurized and cooled by the first compression device and the first cooling device is cooled by the second cooling device and further cooled by the second expander to generate a liquid phase and enter the gas-liquid separation device, and the liquid phase outlet of the gas-liquid separation device is connected to the heating device and the power generation device; and an air separation unit, comprising a first heat exchanger, a second heat exchanger, a first splitter, a first expander, an upper tower and a lower tower of a distillation tower, the gas phase outlet of the gas-liquid separation device is connected to the inlet of the first splitter, one of the outlets of the first splitter is connected to the lower tower through the first heat exchanger, and the other outlet is connected to the upper tower through the first heat exchanger and the first expander in sequence, and the liquid phase outlet of the lower tower is connected to the upper tower through the second heat exchanger.

[0006] Optionally, the gas phase outlet of the upper tower includes a first gas phase outlet located at the top of the upper tower, a second gas phase outlet located in the middle of the upper tower, and a third gas phase outlet located at the bottom of the upper tower. The first gas phase outlet and the second gas phase outlet pass through the second heat exchanger and the cold end of the first heat exchanger in sequence and output products, the third gas phase outlet passes through the cold end of the first heat exchanger and outputs products, and the liquid phase outlet of the lower tower is connected to the outside.

[0007] Optionally, the air separation unit further includes a first throttle valve and a second splitter, the liquid phase outlet of the lower tower includes a first liquid phase outlet, the first liquid phase outlet is connected to the inlet of the second splitter through the hot end of the second heat exchanger and the first throttle valve in sequence, one of the outlets of the second splitter is connected to the upper tower, and the other outlet is connected to the outside.

[0008] Optionally, the energy storage unit further includes a third diverter, an inlet of the third diverter is connected to the liquid phase outlet of the gas-liquid separation device, one of the outlets of the third diverter is connected to the power generation device, and the other outlet is connected to the upper tower.

[0009] Optionally, the air separation unit further includes a first cryogenic pump, a first mixer and a second throttle valve, the liquid phase outlet of the lower tower includes a second liquid phase outlet, the inlet of the first cryogenic pump is connected to one of the outlets of the third splitter, and the outlet is connected to one of the inlets of the first mixer, the second liquid phase outlet is connected to the other inlet of the first mixer through the hot end of the second heat exchanger, and the outlet of the first mixer is connected to the upper tower through the second throttle valve.

[0010] Optionally, the energy storage unit also includes an evaporator and a second cryogenic pump, the inlet of the second cryogenic pump is connected to one of the outlets of the third diverter, the outlet is connected to the heating device through the evaporator, the hot end outlet of the evaporator is connected to one of the cold end inlets of the second cooling device, and the cold end outlet corresponding to the cold end inlet is connected to the hot end inlet of the evaporator.

[0011] Optionally, the air separation unit also includes a fourth diverter, the gas phase outlet of the gas-liquid separation device is connected to one of the cold end inlets of the second cooling device, the cold end outlet corresponding to the cold end inlet is connected to the inlet of the fourth diverter, and one of the outlets of the fourth diverter is connected to the outside for exhaust.

[0012] Optionally, the air separation unit also includes a second mixer and an air compressor, one of the inlets of the second mixer is connected to the other outlet of the fourth diverter, the other inlet is connected to the outside for air replenishment, and the outlet of the second mixer is connected to the inlet of the first diverter through the air compressor.

[0013] Optionally, the energy storage unit also includes a hot oil tank for storing heat, and multiple first compression devices are provided in series, and the outlet of each first compression device is connected to the first cooling device, the cold end outlet of the first cooling device is connected to the inlet of the hot oil tank, and the outlet of the hot oil tank is connected to the heating device.

[0014] Optionally, the energy storage unit also includes a cold oil tank for storing cold, the power generation device is constructed as a steam turbine, and multiple steam turbines are arranged in series, the inlet of each steam turbine is connected to the heating device, the hot end of the heating device is connected to the inlet of the cold oil tank, and the outlet of the cold oil tank is connected to the cold end of the first cooling device.

[0015] Through the above technical scheme, in the energy storage stage, the air is compressed by the first compression device to form a high-pressure and high-temperature state, and the heat generated during the compression process is taken away by the first cooling device to provide heat for the heating device. The cooled high-pressure and normal-temperature air is cooled by the second cooling device to produce a liquid phase, and then the pressure is reduced to normal pressure by the second expander and then enters the gas-liquid separation device for gas-liquid separation; in the air separation stage, the nitrogen-rich gas generated by the gas-liquid separation device is used as the raw gas for air separation, and then cooled by the first heat exchanger and divided into two streams by the first splitter, one of which directly enters the lower tower of the distillation tower for separation, and the other is reduced to a suitable working pressure of the upper tower by the first expansion machine, and then enters the upper tower as the upper tower makeup gas for separation, and the liquid separated from the lower tower is cooled by the second heat exchanger and enters the upper tower for further separation. The energy storage unit is coupled with the air separation unit to make full use of resources.

[0016] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 It is a schematic structural diagram of a double-tower distillation air separation system in the present disclosure.

[0018] Description of Reference Numerals 1. First compression device; 2. First cooling device; 3. Second cooling device; 4. Second expander; 5. Gas-liquid separation device; 6. Third diverter; 7. Second cryogenic pump; 8. Evaporator; 9. Heating device; 10. Power generation device; 11. Cold oil tank; 12. Hot oil tank; 13. Fourth diverter; 14. Second mixer; 15. Air compressor; 16. First diverter; 17. First heat exchanger; 18. First expander; 19. Lower tower; 20. Second heat exchanger; 21. First throttle valve; 22. Second throttle valve; 23. Upper tower; 24. First cryogenic pump; 25. Second diverter; 26. First mixer; 100. Energy storage unit; 200. Air separation unit. DETAILED DESCRIPTION

[0019] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0020] In the present disclosure, unless otherwise stated, directional words such as "upper, lower, left, right" are generally used to refer to... "Inside and outside" refer to the inside and outside relative to the outline of the component or structure itself. In addition, it should be noted that the terms used, such as "first, second", etc., are used to distinguish one element from another element and do not have order and importance. In addition, in the description with reference to the drawings, the same mark in different drawings represents the same element.

[0021] like Figure 1 As shown, the present disclosure provides a double-tower distillation air separation system, including: an energy storage unit 100, including a gas-liquid separation device 5, a first compression device 1, a first cooling device 2, a second cooling device 3, a second expansion machine 4, a heating device 9 and a power generation device 10. The air is pressurized by the first compression device 1 to generate heat, and the heat is taken away by the first cooling device 2 to provide heat for the heating device 9. The air pressurized and cooled by the first compression device 1 and the first cooling device 2 is cooled by the second cooling device 3 and further cooled by the second expansion machine 4 to generate a liquid phase that enters the gas-liquid separation device 5. The gas-liquid separation The liquid phase outlet of the gas-liquid separation device 5 is connected to the heating device 9 and the power generation device 10; and the air separation unit 200 includes a first heat exchanger 17, a second heat exchanger 20, a first splitter 16, a first expander 18, an upper tower 23 of a distillation tower and a lower tower 19, the gas phase outlet of the gas-liquid separation device 5 is connected to the inlet of the first splitter 16, one of the outlets of the first splitter 16 is connected to the lower tower 19 through the first heat exchanger 17, and the other outlet is connected to the upper tower 23 through the first heat exchanger 17 and the first expander 18 in sequence, and the liquid phase outlet of the lower tower 19 is connected to the upper tower 23 through the second heat exchanger 20.

[0022] Through the above technical scheme, in the energy storage stage, the air is compressed by the first compression device 1 to form a high-pressure and high-temperature state, and the heat generated in the compression process is taken away by the first cooling device 2 to provide heat for the heating device 9, so as to recover and utilize the energy, improve the energy efficiency of the energy storage unit 100, ensure the effective utilization of energy, and provide thermal energy support for the subsequent energy release stage. The cooled high-pressure and normal-temperature air is cooled by the second cooling device 3 to produce a liquid phase, and then the pressure is reduced to normal pressure by the second expander 4 and then enters the gas-liquid separation device 5 for gas-liquid separation; in the air separation stage, the nitrogen-rich gas generated by the gas-liquid separation device 5 is used as the raw gas for air separation, and is cooled by the first heat exchanger 17 and then divided into two streams by the first splitter 16. One stream directly enters the lower tower 19 of the distillation tower for separation, and the other stream is reduced in pressure to a suitable working pressure of the upper tower 23 by the first expansion machine 18, and then enters the upper tower 23 as the upper tower 23 supplementary gas for separation. The liquid separated from the lower tower 19 is cooled by the second heat exchanger 20 and then enters the upper tower 23 for further separation. For example, the second heat exchanger 20 is constructed as a reheater. The energy storage unit 100 is coupled with the air separation unit 200 to make full use of resources. The system purifies and compresses the air through the same set of air filters, molecular sieve purifiers and compression devices, and uses part of the liquefied air as feed for air separation, and then extracts high-purity oxygen and nitrogen through double-tower distillation. The other part of the remaining liquid air generates electricity by heating and expansion during the energy release stage, which reduces the system structure, reduces the exhaust capacity loss, reduces the system construction cost, and improves the economic benefits. The energy storage unit 100 of this system can operate independently, and the raw gas does not have to pass through the air separation unit 200 to store energy and generate electricity. In this way, in the scenario where only energy storage is required, the energy loss of the air separation unit 200 is reduced and the efficiency of the energy storage unit 100 is improved.

[0023] As an optional embodiment, the gas phase outlet of the upper tower 23 includes a first gas phase outlet located at the top of the upper tower 23, a second gas phase outlet located in the middle of the upper tower 23, and a third gas phase outlet located at the bottom of the upper tower 23. The first gas phase outlet and the second gas phase outlet sequentially pass through the second heat exchanger 20 and the cold end of the first heat exchanger 17 and output products. The third gas phase outlet passes through the cold end of the first heat exchanger 17 and outputs products. The liquid phase outlet of the lower tower 19 is connected to the outside. The cold sources of the first heat exchanger 17 and the second heat exchanger 20 come from the gaseous nitrogen separated by the upper tower 23. Dirty nitrogen and gaseous oxygen, gaseous nitrogen is separated from the first gas phase outlet at the top of the upper tower 23, and dirty nitrogen is separated from the second gas phase outlet in the middle, and are cooled in the second heat exchanger 20 and the first heat exchanger 17 respectively, and then are led out as product gaseous nitrogen product and dirty nitrogen product. Liquid oxygen and gaseous oxygen are separated from the bottom of the upper tower 23, and liquid oxygen is directly led out as a product through the liquid phase outlet, and gaseous oxygen separated from the third gas phase outlet is led out as a gaseous oxygen product after being cooled in the first heat exchanger 17, so as to make full use of the cold capacity of the gas separated by the upper tower 23, recover energy, and make full use of resources.

[0024] As an optional embodiment, the air separation unit 200 further includes a first throttle valve 21 and a second diverter 25. The liquid phase outlet of the lower tower 19 includes a first liquid phase outlet. The first liquid phase outlet passes through the hot end of the second heat exchanger 20 and the first throttle valve 21 and is connected to the inlet of the second diverter 25 in sequence. One of the outlets of the second diverter 25 is connected to the upper tower 23, and the other outlet is connected to the outside. After the raw gas enters the lower tower 19, it is separated into liquid nitrogen and liquid air. The liquid nitrogen is first depressurized by the first throttle valve 21, and then a small amount of liquid nitrogen product is diverted by the second diverter 25. Most of the remaining liquid nitrogen enters the upper part of the upper tower 23 for separation.

[0025] As an optional embodiment, the energy storage unit 100 also includes a third diverter 6, the inlet of the third diverter 6 is connected to the liquid phase outlet of the gas-liquid separation device 5, one of the outlets of the third diverter 6 is connected to the power generation device 10, and the other outlet is connected to the upper tower 23. The liquid air generated by the gas-liquid separation device 5 is diverted through the third diverter 6, one part is connected to the power generation device 10 for power generation, and the other part is used as the separation raw material of the upper tower 23, thereby improving the comprehensive benefits of the system.

[0026] As an optional embodiment, the air separation unit 200 also includes a first cryogenic pump 24, a first mixer 26 and a second throttle valve 22. The liquid phase outlet of the lower tower 19 includes a second liquid phase outlet. The inlet of the first cryogenic pump 24 is connected to one of the outlets of the third splitter 6, and the outlet is connected to one of the inlets of the first mixer 26. The second liquid phase outlet is connected to the other inlet of the first mixer 26 through the hot end of the second heat exchanger 20. The outlet of the first mixer 26 is connected to the upper tower 23 through the second throttle valve 22. After the raw gas enters the lower tower 19, it is separated into liquid nitrogen and liquid air. A small amount of liquid air from the liquid phase outlet of the gas-liquid separation device 5 is pressurized by the first cryogenic pump 24 and then merged with the liquid air separated by the lower tower 19 as the raw material separated by the upper tower 23. After being depressurized by the second throttle valve 22, it enters the middle part of the upper tower 23 for separation.

[0027] Optionally, the energy storage unit 100 also includes an evaporator 8 and a second cryogenic pump 7, the inlet of the second cryogenic pump 7 is connected to one of the outlets of the third diverter 6, and the outlet is connected to the heating device 9 through the evaporator 8, the hot end outlet of the evaporator 8 is connected to one of the cold end inlets of the second cooling device 3, and the cold end outlet corresponding to the cold end inlet is connected to the hot end inlet of the evaporator 8. Normal-pressure liquid air is first pressurized by the second cryogenic pump 7, and then enters the evaporator 8 to cool, becoming normal-temperature and high-pressure gaseous air. The released cold energy serves as one of the cold sources of the second cooling device 3, so that energy is fully utilized. After releasing the cold energy, the normal-temperature air returns to the evaporator 8 again to evaporate the liquid air.

[0028] As an optional embodiment, the air separation unit 200 also includes a fourth diverter 13, the gas phase outlet of the gas-liquid separation device 5 is connected to one of the cold end inlets of the second cooling device 3, the cold end outlet corresponding to the cold end inlet is connected to the inlet of the fourth diverter 13, and one of the outlets of the fourth diverter 13 is connected to the outside for exhaust. The gas phase outlet of the gas-liquid separation device 5 produces low-temperature nitrogen-rich gas as a cold source for the second cooling device 3. After cooling, part of the air is discharged into the atmosphere through the fourth diverter 13 as a raw gas for air separation, so as to match the cold capacity that can be used in the air separation part, so as to avoid the problem of poor distillation effect caused by insufficient cold capacity.

[0029] Optionally, the air separation unit 200 also includes a second mixer 14 and an air compressor 15. One of the inlets of the second mixer 14 is connected to the other outlet of the fourth diverter 13, and the other inlet is connected to the outside for air replenishment. The outlet of the second mixer 14 is connected to the inlet of the first diverter 16 through the air compressor 15. The nitrogen content in the air separation raw gas is reduced by replenishing air from the external environment to ensure the safe and stable operation of the subsequent air separation process. The raw gas is pressurized to a suitable working pressure of the distillation tower by the air compressor 15 and then enters the upper tower 23 and the lower tower 19 of the distillation tower for distillation.

[0030] As an optional embodiment, the energy storage unit 100 also includes a hot oil tank 12 for storing heat. A plurality of first compression devices 1 are arranged in series, and the outlet of each first compression device 1 is connected to a first cooling device 2. The cold end outlet of the first cooling device 2 is connected to the inlet of the hot oil tank 12. The outlet of the hot oil tank 12 is connected to the heating device 9. The air undergoes multi-stage compression and multi-stage cooling. The heat generated by the compression is taken away by the first cooling device 2 after heat exchange with the heat transfer oil, and is stored in the hot oil tank 12 to provide heat for the heating device 9, so that the energy is fully utilized.

[0031] Optionally, the energy storage unit 100 also includes a cold oil tank 11 for storing cold. The power generation device 10 is constructed as a steam turbine. A plurality of steam turbines are arranged in series. A heating device 9 is connected to the inlet of each steam turbine. The hot end of the heating device 9 is connected to the inlet of the cold oil tank 11. The outlet of the cold oil tank 11 is connected to the cold end of the first cooling device 2. The liquid air generated by the liquid phase outlet of the gas-liquid separation device 5 is heated by the evaporator 8, and then heated step by step by multiple heating devices 9. The energy is released and electricity is generated by the step-by-step expansion of multiple steam turbines. After three-stage expansion, the energy in the high-pressure air is completely released. After the heat release of the heating device 9, the cold is taken away by the heat transfer oil and stored in the cold oil tank 11 to provide a cold source for the first cooling device 2, so that the energy is fully utilized.

[0032] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0033] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0034] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A double-tower distillation air separation system, characterized in that: include: The energy storage unit includes a gas-liquid separation device, a first compression device, a first cooling device, a second cooling device, a second expander, a heating device and a power generation device. The air is pressurized by the first compression device to generate heat, and the heat is taken away by the first cooling device to provide heat for the heating device. The air pressurized and cooled by the first compression device and the first cooling device is cooled by the second cooling device and further cooled by the second expander to generate a liquid phase that enters the gas-liquid separation device. The liquid phase outlet of the gas-liquid separation device is connected to the heating device and the power generation device. as well as An air separation unit comprises a first heat exchanger, a second heat exchanger, a first splitter, a first expander, an upper tower and a lower tower of a distillation tower, the gas phase outlet of the gas-liquid separation device is connected to the inlet of the first splitter, one of the outlets of the first splitter is connected to the lower tower through the first heat exchanger, and the other outlet is connected to the upper tower through the first heat exchanger and the first expander in sequence, and the liquid phase outlet of the lower tower is connected to the upper tower through the second heat exchanger.

2. The double-tower rectification air separation system according to claim 1, characterized in that: The gas phase outlet of the upper tower includes a first gas phase outlet located at the top of the upper tower, a second gas phase outlet located in the middle of the upper tower, and a third gas phase outlet located at the bottom of the upper tower. The first gas phase outlet and the second gas phase outlet pass through the second heat exchanger and the cold end of the first heat exchanger in sequence and output products. The third gas phase outlet passes through the cold end of the first heat exchanger and outputs products. The liquid phase outlet of the lower tower is connected to the outside.

3. The double-tower distillation air separation system according to claim 1, characterized in that: The air separation unit also includes a first throttle valve and a second splitter. The liquid phase outlet of the lower tower includes a first liquid phase outlet. The first liquid phase outlet is connected to the inlet of the second splitter through the hot end of the second heat exchanger and the first throttle valve in sequence. One of the outlets of the second splitter is connected to the upper tower, and the other outlet is connected to the outside.

4. The double-tower rectification air separation system according to claim 1, characterized in that: The energy storage unit also includes a third diverter, the inlet of the third diverter is connected to the liquid phase outlet of the gas-liquid separation device, one of the outlets of the third diverter is connected to the power generation device, and the other outlet is connected to the upper tower.

5. The double-tower rectification air separation system according to claim 4, characterized in that: The air separation unit also includes a first cryogenic pump, a first mixer and a second throttle valve. The liquid phase outlet of the lower tower includes a second liquid phase outlet. The inlet of the first cryogenic pump is connected to one of the outlets of the third splitter, and the outlet is connected to one of the inlets of the first mixer. The second liquid phase outlet is connected to the other inlet of the first mixer through the hot end of the second heat exchanger, and the outlet of the first mixer is connected to the upper tower through the second throttle valve.

6. The double-tower rectification air separation system according to claim 4, characterized in that: The energy storage unit also includes an evaporator and a second cryogenic pump, the inlet of the second cryogenic pump is connected to one of the outlets of the third diverter, and the outlet is connected to the heating device through the evaporator, the hot end outlet of the evaporator is connected to one of the cold end inlets of the second cooling device, and the cold end outlet corresponding to the cold end inlet is connected to the hot end inlet of the evaporator.

7. The double-tower rectification air separation system according to claim 1, characterized in that: The air separation unit also includes a fourth diverter, the gas phase outlet of the gas-liquid separation device is connected to one of the cold end inlets of the second cooling device, the cold end outlet corresponding to the cold end inlet is connected to the inlet of the fourth diverter, and one of the outlets of the fourth diverter is connected to the outside for exhaust.

8. The double-tower rectification air separation system according to claim 7, characterized in that: The air separation unit also includes a second mixer and an air compressor, one of the inlets of the second mixer is connected to the other outlet of the fourth diverter, the other inlet is connected to the outside for air replenishment, and the outlet of the second mixer is connected to the inlet of the first diverter through the air compressor.

9. The double-tower rectification air separation system according to claim 1, characterized in that: The energy storage unit also includes a hot oil tank for storing heat. A plurality of the first compression devices are connected in series. The outlet of each of the first compression devices is connected to the first cooling device. The cold end outlet of the first cooling device is connected to the inlet of the hot oil tank, and the outlet of the hot oil tank is connected to the heating device.

10. The double-tower rectification air separation system according to claim 9, characterized in that: The energy storage unit also includes a cold oil tank for storing cold. The power generation device is constructed as a steam turbine. A plurality of steam turbines are arranged in series. The inlet of each steam turbine is connected to the heating device. The hot end of the heating device is connected to the inlet of the cold oil tank, and the outlet of the cold oil tank is connected to the cold end of the first cooling device.

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