CN-122015429-A - Compressed air separation-liquid air energy storage coupling method for stably switching storage and release working conditions

CN122015429ACN 122015429 ACN122015429 ACN 122015429ACN-122015429-A

Abstract

The invention provides an internal compression air separation-liquid air energy storage coupling method for stably switching storage and release working conditions, and relates to the technical field of cryogenic air separation. In the method, gaseous raw materials subjected to air separation and rectification are continuously provided by an air separation self-compressor, and liquid raw materials subjected to air separation and rectification are continuously input by a liquid air energy storage system. And the liquid product obtained by air separation and rectification only has a small part for providing cold energy for an air separation system, and most of cold energy of the liquid product is input into a liquid air energy storage system in a direct or indirect mode to provide a cold energy source for air liquefaction in an energy storage process so as to realize the complementary utilization of the cold energy of the air and the liquid air energy storage system. The internal compression air separation system does not need to be provided with pressurizing and expanding equipment, and can realize stable switching of the storage/release working conditions of the coupling system only by adjusting the proportion of the output flow path of the air separation liquid product flow and changing the direction of the flow path of the cold accumulator. The method can realize large-scale and distributed energy storage, and simultaneously can reduce the consumption of air separation equipment and the electricity cost for air separation operation.

Inventors

HE XIUFEN
WANG LI
TONG LIGE
ZUO ZHONGQI
LIU CHUANPING
ZHANG PEIKUN
GUO WEI

Assignees

北京科技大学

Dates

Publication Date: 20260512
Application Date: 20260228

Claims (9)

1. The compressed air separation-liquid air energy storage coupling method for stably switching the storage and release working conditions is characterized by being realized by cooperation of an air separation unit and a liquefied energy storage unit and specifically comprises the following steps of: s1, an energy storage process, wherein an air separation unit and a liquefied energy storage unit synchronously operate: S11, the ambient air in the air separation unit is compressed, cooled, washed and dried by an air compression system, a precooling system and a purification system I, and then enters a heat exchanger I, and gaseous raw materials are provided for an air separation rectification system after being cooled; S12, the ambient air in the liquefied energy storage unit sequentially passes through a compressor, a first cooler, a second purification system, a booster and a second cooler to be compressed, cooled and purified and then enters a second heat exchanger; s13, passing the high-pressure air liquefied by the second heat exchanger through an expander, and entering a liquid-air storage tank; S14, air output from the liquid-air storage tank enters a second heat exchanger for reheating and then is recycled to enter a compressor inlet, and low-temperature liquid air output from the liquid-air storage tank is pressurized by a liquid-air pump and then is input into an air separation unit rectifying system to provide liquid raw materials for the air separation rectifying system; s15, the liquid oxygen output by the air separation and rectification system is divided into two parts after being pressurized by a liquid oxygen pump, wherein more than 90% of the liquid oxygen enters a heat exchanger II of the liquefied energy storage unit for gasification and rewarming, and the rest part of the liquid oxygen directly enters a heat exchanger I of the air separation unit for gasification and rewarming; S2, in the energy release process, a compressor, a first cooler, a second purification system, a booster, a second cooler, an expansion refrigeration unit, a second heat exchanger and an expander of the liquefied energy storage unit stop running, and low-temperature liquid in the liquid-air storage tank is fed into an air separation rectification system to participate in rectification after being pressurized by a liquid-air pump; the air separation unit maintains the same running state as the energy storage process, and the liquid oxygen product entering the heat exchanger II in the energy storage process is switched to the liquid oxygen evaporator, so that the operation of the coupling system under the working condition of storage/release is realized.
2. The method for coupling compressed air to liquid air energy storage for stable switching of a storage and release working condition according to claim 1, wherein the air in the S11 enters an air separation and rectification system after heat exchange in a heat exchanger I, liquid oxygen, nitrogen and polluted nitrogen are obtained through separation in the air separation and rectification system, and the nitrogen and the polluted nitrogen are output to the air separation and rectification system after reheating by the heat exchanger I.
3. The method for coupling compressed air to liquid air energy storage for stable switching of a storage and release working condition according to claim 2, wherein during the energy storage process, after the nitrogen and the polluted nitrogen are output to the air separation system, the stored cold energy is extracted through the cold accumulator, and then the cold energy is supplied to the heat exchanger II for high-pressure air liquefaction.
4. The compressed air-liquid air energy storage coupling method for stably switching the storage and release working conditions according to claim 1, wherein 11% -15% of high-pressure air in the second heat exchanger in the S13 is pumped out from the middle of the second heat exchanger, enters an expansion refrigeration unit, and cold air output after expansion refrigeration enters the second heat exchanger for reheating and then enters the second purification system.
5. The method for coupling compressed air to liquid air energy storage in stable switching of a storage and release working condition according to claim 1, wherein in the step S2, in the liquid oxygen evaporator, the liquid oxygen product is gasified and reheated and then is output to the oxygen main pipe network, the liquid oxygen gasification cold energy is stored in the regenerator by using the polluted nitrogen or nitrogen output by the air separator as a carrier, and the polluted nitrogen or nitrogen passing through the regenerator is converged into the polluted nitrogen or nitrogen main pipe network output by the air separator after being reheated.
6. The method for coupling compressed air to liquid air energy storage and release working condition stable switching according to claim 1, wherein the oxygen after reheating in the first heat exchanger S11 and the second heat exchanger S12 is totally converged into an oxygen main pipe network.
7. The compressed air-liquid air energy storage coupling method for stably switching the storage and release working conditions according to claim 1, wherein the air separation unit comprises an air compression system, a precooling system, a purification system, a first heat exchanger, a rectification system and a liquid oxygen pump; The liquefied energy storage unit comprises a compressor, a first cooler, a second purification system, a supercharger, a second cooler, an expansion refrigeration unit, a second heat exchanger, a liquid-air storage tank, a liquid-air pump, a cold accumulator, a liquid oxygen evaporator and an expander.
8. The method for coupling internal compression air separation and liquid air energy storage for stably switching a storage and release working condition according to claim 7, wherein the air compression system, the precooling system, the purification system and the heat exchanger I are sequentially connected, an air outlet of the heat exchanger I is connected with the rectification system, a nitrogen outlet and a dirty nitrogen outlet of the rectification system are respectively connected with a nitrogen inlet and a dirty nitrogen inlet of the heat exchanger I, an oxygen outlet of the rectification system is connected with a liquid oxygen pump inlet, the liquid oxygen pump outlet is respectively connected with an oxygen inlet of the heat exchanger I, a liquid oxygen evaporator and a second oxygen inlet of the heat exchanger, an oxygen outlet of the heat exchanger I, an oxygen outlet of the liquid oxygen evaporator and an oxygen outlet of the second oxygen of the heat exchanger are all connected with an oxygen total pipe network, a nitrogen outlet of the heat exchanger I is connected with the nitrogen total pipe network, and a dirty nitrogen outlet of the heat exchanger I is connected with the precooling system, the purification system I, the cold accumulator and the liquid oxygen evaporator; The compressor, the first cooler, the second purification system, the booster, the second cooler and the second heat exchanger are sequentially connected, a liquid air outlet of the second heat exchanger is connected with the expander, a high-pressure air outlet of the second heat exchanger is connected with the expansion refrigeration unit, an outlet of the expansion refrigeration unit is connected with the second heat exchanger, an outlet of the expander is connected with the liquid air storage tank, an air outlet of the liquid air storage tank is connected with the second heat exchanger, a liquid air outlet of the liquid air storage tank is connected with the liquid air pump, the liquid air pump is connected with the rectification system, the other air outlet of the second heat exchanger is connected with the compressor, a third air outlet of the second heat exchanger is connected with the second purification system, and a dirty nitrogen outlet of the second heat exchanger is connected with the pre-cooling system and the first purification system; the cold accumulator is connected with the second heat exchanger, the first heat exchanger and the liquid oxygen evaporator, and a dirty nitrogen outlet of the cold accumulator is connected to the precooling system and the purifying system; The liquid oxygen evaporator is connected with the first heat exchanger and the second heat exchanger, and an oxygen outlet of the liquid oxygen evaporator is connected to an oxygen main pipe network.
9. The compressed air-liquid air energy storage coupling method for stably switching the storage and release working conditions according to claim 1, wherein valves are respectively arranged on pipelines of the liquid oxygen pump for connecting the second heat exchanger and the liquid oxygen evaporator; a valve is arranged on a pipeline connected with the cold accumulator through the heat exchanger; A valve is arranged on a pipeline connected with the cold accumulator and the second heat exchanger; a valve is arranged on a pipeline connected with the cold accumulator and the liquid oxygen evaporator; And a valve is arranged on a pipeline connected with the cold accumulator, the precooling system and the purifying system.

Description

Compressed air separation-liquid air energy storage coupling method for stably switching storage and release working conditions Technical Field The invention relates to the technical field of cryogenic air separation, in particular to an internal compression air separation-liquid air energy storage coupling method for stably switching storage and release working conditions. Background The air separation is used as high-power-consumption equipment, the annual power consumption in China can reach about 5% of the total annual power consumption, and the air separation has the characteristic of large-scale power consumption. The air separation equipment and the liquid air energy storage system are coupled, so that the distributed and large-scale energy storage of the industrial equipment at the load side can be realized, the operation electricity cost of the air separation equipment can be reduced by utilizing the advantages of peak-valley load switching and electricity price difference of the energy storage technology, and the economic benefit of an air separation enterprise is remarkably improved. However, the continuous operation requirement of the air separation device contradicts the periodic variable load requirement of the liquid air energy storage technology, so that the air separation device is required to operate under wide working conditions such as a compressor, a supercharger, an expander, a heat exchange device and the like when the storage and release working conditions are switched, and particularly the supercharger, the expander and the like may be required to be started and stopped repeatedly to dynamically adjust the cold balance in the air separation system, which contradicts the continuous stable operation requirement of the air separation device, and restricts the popularization and application of the liquid air energy storage technology in the air separation industry. Disclosure of Invention In order to solve the technical problems of wide working condition variable load requirements of air equipment and frequent start and stop of partial equipment in the air and liquid air energy storage coupling technology storage/release working condition switching in the prior art, the embodiment of the invention provides an internal compression air separation-liquid air energy storage coupling method for stably switching the storage and release working conditions. The technical scheme is as follows: The method is realized by cooperation of an air separation unit and a liquefied energy storage unit, and specifically comprises the following steps: s1, an energy storage process, wherein an air separation unit and a liquefied energy storage unit synchronously operate: S11, the ambient air in the air separation unit is compressed, cooled, washed and dried by an air compression system, a precooling system and a purification system I, and then enters a heat exchanger I, and gaseous raw materials are provided for an air separation rectification system after being cooled; S12, the ambient air in the liquefied energy storage unit sequentially passes through a compressor, a first cooler, a second purification system, a booster and a second cooler to be compressed, cooled and purified and then enters a second heat exchanger; s13, passing the high-pressure air liquefied by the second heat exchanger through an expander, and entering a liquid-air storage tank; S14, air output from the liquid-air storage tank enters a second heat exchanger for reheating and then is recycled to enter a compressor inlet, and low-temperature liquid air output from the liquid-air storage tank is pressurized by a liquid-air pump and then is input into an air separation unit rectifying system to provide liquid raw materials for the air separation rectifying system; s15, the liquid oxygen output by the air separation and rectification system is divided into two parts after being pressurized by a liquid oxygen pump, wherein more than 90% of the liquid oxygen enters a heat exchanger II of the liquefied energy storage unit for gasification and rewarming, and the rest part of the liquid oxygen directly enters a heat exchanger I of the air separation unit for gasification and rewarming; S2, in the energy release process, a compressor, a first cooler, a second purification system, a booster, a second cooler, an expansion refrigeration unit, a second heat exchanger and an expander of the liquefied energy storage unit stop running, and low-temperature liquid in the liquid-air storage tank is fed into an air separation rectification system to participate in rectification after being pressurized by a liquid-air pump; the air separation unit maintains the same running state as the energy storage process, and the liquid oxygen product entering the heat exchanger II in the energy storage process is switched to the liquid oxygen evaporator, so that the operation of the coupling system under the working condition of storage/release is realized. And in S11