Low-temperature energy storage and self-dehumidification type blast furnace blast system

Abstract

The invention provides a low-temperature energy storage and self-dehumidification type blast furnace blast system, and relates to the technical field of blast furnace ironmaking. The system comprises a liquefied air energy storage device, a pressurized gasification and cold storage subsystem, a waste heat recovery subsystem and an expansion power generation subsystem, in the off-peak electricity period, the liquefied air energy storage device liquefies and stores air through low-price electric energy, in the non-off-peak electricity period, the pressurized gasification and cold storage subsystem pressurizes and gasifies the stored liquid air and recovers and stores cold energy, and in the non-off-peak electricity period, the waste heat recovery subsystem recovers and stores the cold energy. A heat accumulator and a waste heat exchanger of the waste heat recovery subsystem are used for recycling compression heat and industrial waste heat, and the expansion power generation subsystem enables pressurized and gasified air to act through an expansion machine to drive a power generator to generate power. The method can effectively reduce the moisture content in blast of the blast furnace, form oxygen-enriched blast, improve the theoretical combustion temperature in the blast furnace, reduce the comprehensive coke ratio of ironmaking, improve the yield of the blast furnace, and realize large-scale energy storage technology and application in iron and steel enterprises.

Description

Technical Field

[0001] The present invention relates to the technical field of blast furnace ironmaking, and particularly to a low-temperature energy storage and self-dehumidifying blast furnace air supply system. Background Art

[0002] Blast furnace air supply is an important technological process in iron and steel enterprises and also a large consumer of electricity (or steam). Existing blast furnace air supply systems have problems such as high energy consumption and poor dehumidification effect, which limit the increase of the theoretical combustion temperature in the blast furnace, the reduction of the comprehensive coke ratio in ironmaking, and the improvement of the blast furnace output. Combining the blast furnace air supply system with energy storage technology can achieve significant economic and social benefits. Summary of the Invention

[0003] In order to solve the above technical problems existing in the prior art, an embodiment of the present invention provides a low-temperature energy storage and self-dehumidifying blast furnace air supply system. The technical solution is as follows:

[0004] A low-temperature energy storage and self-dehumidifying blast furnace air supply system includes a liquefied air energy storage device, a pressurized gasification and cold energy storage subsystem, a waste heat recovery subsystem, and an expansion power generation subsystem.

[0005] The liquefied air energy storage device includes an air liquefaction device and a liquid air storage tank, and is used for liquefying and storing air using low-cost electric energy during off-peak power periods.

[0006] The pressurized gasification and cold energy storage subsystem includes a low-temperature booster pump and a cold energy storage purifier, and is used for pressurizing, gasifying, and recovering and storing cold energy of the stored liquid air during non-off-peak power periods.

[0007] The waste heat recovery subsystem includes a heat accumulator and a waste heat exchanger, which are respectively used for recovering and utilizing compression heat and industrial waste heat.

[0008] The expansion power generation subsystem includes an expander and a generator, and is used for driving the generator to generate electricity by the work of the expander on the pressurized and gasified air.

[0009] The outlet of the air liquefaction device is connected to the inlet of the liquid air storage tank through a pipeline, the outlet of the liquid air storage tank is connected to the low-temperature booster pump through a pipeline, a regulating valve I is arranged on the pipeline connecting the low-temperature booster pump and the cold energy storage purifier, the cold energy storage purifier is connected to the inlet of the air liquefaction device, and a regulating valve III is arranged on the pipeline connecting the cold energy storage purifier and the air liquefaction device. The other end of the cold energy storage purifier is connected to the heat accumulator and the cold energy recovery device, the outlet of the heat accumulator is connected to the waste heat exchanger, the outlet of the waste heat exchanger is connected to the expander, the expander drives the generator to generate electricity, and the outlet of the expander is connected to the hot blast stove.

[0010] The inlet of the pipeline in the heat accumulator is connected to the outlet of the air compressor, the inlet of the air compressor is connected to the outlet of the air filter, and the outlet of the pipeline in the heat accumulator is connected to the cold energy recovery device.

[0011] A regulating valve two is provided on the pipeline connecting the inlet of the pipeline in the cold storage purifier and the cold energy recovery device. The outlet of the pipeline in the cold energy recovery device is connected to the heat accumulator. A regulating valve four is provided on the pipeline of the cold storage purifier leading to the external air environment. A regulating valve five is provided on the pipeline connecting the cold storage purifier and the heat accumulator.

[0012] The waste heat exchanger is internally provided with a waste heat pipeline.

[0013] The cold energy recovery device is replaced by an adsorption type air purifier. At this time, the cold storage purifier is replaced by a cold storage device.

[0014] There is at least one cold storage purifier and one heat accumulator. Multiple cold storage purifiers are connected in parallel, and multiple heat accumulators are connected in parallel.

[0015] The working process of the system is as follows:

[0016] S1. During the valley electricity period, the low-temperature booster pump, regulating valve one, regulating valve four, and regulating valve five are closed, and other valves are fully open. The air from the environment is filtered by the air filter and then compressed in the air compressor. Then it enters the pipeline in the heat accumulator to release heat and cool down, and then enters the cold storage purifier through the cold energy recovery device for purification and cold energy recovery. After that, it is divided into part A and part B. Among them, part A enters the air liquefaction device to be liquefied and then enters the liquid air storage tank. Part B enters the heat accumulator to be heated after recovering cold energy through the pipeline in the cold energy recovery device, and further enters the expansion machine to expand and do work after being heated in the waste heat exchanger, and then enters the hot blast stove as blast furnace air. At the same time, the expansion machine drives the generator to generate electricity.

[0017] S2. At the end of the valley electricity period, regulating valve three and regulating valve two are closed, and regulating valve four is opened. The moisture, carbon dioxide, and hydrocarbon impurities frozen in the inclined temperature layer at the outlet of the cold storage purifier during the valley electricity period are reheated and sublimated and discharged through regulating valve four. After the discharge is completed, the air compressor and regulating valve four are closed.

[0018] S3. At the end of the valley electricity period and during the non-valley electricity period, regulating valve one and regulating valve five are opened. The liquid air stored in the liquid air storage tank during the valley electricity period is pressurized by the low-temperature booster pump, releases cold energy in the cold storage purifier, then enters the heat accumulator for reheating, and further enters the expansion machine to expand and do work after being heated in the waste heat exchanger, and then enters the hot blast stove as blast furnace air. At the same time, the expansion machine drives the generator to generate electricity.

[0019] During the valley electricity period, the hybrid operation mode of step S1 plus S3 can also be adopted. The first regulating valve, the third regulating valve, and the fifth regulating valve are opened, the second regulating valve and the fourth regulating valve are closed, and the low-temperature booster pump operates. The air from the environment is filtered by the air filter and then compressed in the air compressor, and then enters the inner pipeline of the regenerator to release heat and cool down, and then enters the cold energy recovery device and then enters the cold storage purifier for purification and cold energy recovery. After that, it enters the air liquefaction device to be liquefied and then enters the liquid air storage tank. The liquid air stored in the liquid air storage tank during the valley electricity period is pressurized by the low-temperature booster pump, releases cold energy in the cold storage purifier, then enters the regenerator for reheating, and is further heated in the waste heat exchanger and then enters the expander to expand and do work. After that, it enters the hot blast stove as the blast for the blast furnace. At the same time, the expander drives the generator to generate electricity.

[0020] When the cold energy recovery device is replaced by the air purifier, part B of the pipeline is omitted in step S1, and the moisture, carbon dioxide, and hydrocarbon impurities in the cold storage purifier in step S2 have been purified and removed when passing through the air purifier.

[0021] In part A of step S1, it is N times the mass flow rate of part B, and the value of N is 2 - 6; during the non-valley electricity period of step S3, the mass flow rates of part A and part B are zero.

[0022] The function of the cold storage purifier during the non-valley electricity period is to store the cold energy of the liquid air gasification, and during the valley electricity period, it is to freeze the moisture, carbon dioxide, and hydrocarbon impurities in the air and release cold energy to the air.

[0023] The outlet pressure of the air compressor is 0.2 - 0.7 MPa.

[0024] The pressure of the liquid air leaving the low-temperature booster pump is 0.2 - 10 MPa; the moisture content of the air entering the hot blast stove is less than or equal to 10 ppm.

[0025] The system changes the oxygen enrichment degree of the liquid air by adjusting the air liquefaction rate of the air liquefaction device, so as to flexibly adapt to the requirements of the blast furnace for the oxygen enrichment degree of the blast. Generally, in proportion, when the air liquefaction rate is 82% - 56%, the oxygen enrichment degree of the blast is about 1% - 8%.

[0026] The beneficial effects brought by the technical solution provided by the embodiment of the present invention at least include:

[0027] In the above solution, during the valley electricity period, low-cost electric energy is used to liquefy and store air; during the non-valley electricity period, the stored liquid air is pressurized and gasified to generate electricity and then used as the blast for the blast furnace. Through this system, the moisture and carbon dioxide contents in the blast for the blast furnace are less than or equal to 10 ppm respectively, and at the same time, oxygen-enriched blast can be formed, which can effectively increase the theoretical combustion temperature in the blast furnace, thereby reducing the comprehensive coke ratio in ironmaking and increasing the output of the blast furnace. Brief Description of the Drawings

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0029] Figure 1 is a schematic structural diagram of a low-temperature energy storage and self-dehumidifying blast furnace air supply system provided by an embodiment of the present invention;

[0030] Figure 2 is a schematic structural diagram of another form of the low-temperature energy storage and self-dehumidifying blast furnace air supply system in the embodiment of the present invention.

[0031] Wherein: 1 - air liquefaction device; 2 - liquid air storage tank; 3 - low-temperature booster pump; 4 - regulating valve I; 5 - regulating valve II; 6 - regulating valve III; 7 - regulating valve IV; 8 - cold storage purifier; 9 - regulating valve V; 10 - heat accumulator; 11 - waste heat exchanger; 12 - expander; 13 - generator; 14 - hot blast stove; 15 - waste heat pipeline; 16 - air compressor; 17 - air filter; 18 - cold energy recovery device; 19 - air purifier; 20 - cold storage device; 21 - regulating valve VI. Detailed implementation manners

[0032] The following describes the technical solutions in the present invention with reference to the drawings.

[0033] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "example" in the present invention should not be construed as more preferred or more advantageous than other embodiments or design solutions. Exactly speaking, the use of the word "example" is intended to present concepts in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one of the two.

[0034] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the drawings and specific embodiments.

[0035] The embodiments of the present invention provide a low-temperature energy storage and self-dehumidifying blast furnace air supply system. As Figure 1 shown in the low-temperature energy storage and self-dehumidifying blast furnace air supply system, it includes a liquefied air energy storage device, a pressurized gasification and cold storage subsystem, a waste heat recovery subsystem, and an expansion power generation subsystem.

[0036] The liquefied air energy storage device includes an air liquefaction device 1 and a liquid air storage tank 2.

[0037] The pressurized gasification and cold storage subsystem includes a cryogenic booster pump 3 and a cold storage purifier 8.

[0038] The waste heat recovery subsystem includes a heat accumulator 10 and a waste heat exchanger 11.

[0039] The expansion power generation subsystem includes an expander 12 and a generator 13.

[0040] The outlet of the air liquefaction device 1 is connected to the inlet of the liquid air storage tank 2 through a pipeline, the outlet of the liquid air storage tank 2 is connected to the cryogenic booster pump 3 through a pipeline, a regulating valve 4 is arranged on the pipeline connecting the cryogenic booster pump 3 and the cold storage purifier 8, the cold storage purifier 8 is connected to the inlet of the air liquefaction device 1, and a regulating valve 6 is arranged on the pipeline connecting the cold storage purifier 8 and the air liquefaction device 1. The other end of the cold storage purifier 8 is connected to the heat accumulator 10 and the cold energy recovery device 18. The outlet of the heat accumulator 10 is connected to the waste heat exchanger 11, the outlet of the waste heat exchanger 11 is connected to the expander 12, the expander 12 drives the generator 13 to generate electricity, and the outlet of the expander 12 is connected to the hot blast stove 14.

[0041] The inlet of the pipeline in the heat accumulator 10 is connected to the outlet of the air compressor 16, the inlet of the air compressor 16 is connected to the outlet of the air filter 17, and the outlet of the pipeline in the heat accumulator 10 is connected to the cold energy recovery device 18.

[0042] A regulating valve 5 is arranged on the pipeline connecting the inlet of the pipeline in the cold storage purifier 8 and the cold energy recovery device 18. The outlet of the pipeline in the cold energy recovery device 18 is connected to the heat accumulator 10. A regulating valve 7 is arranged on the pipeline of the cold storage purifier 8 leading to the external air environment. A regulating valve 9 is arranged on the pipeline connecting the cold storage purifier 8 and the heat accumulator 10.

[0043] A waste heat pipeline 15 passes through the waste heat exchanger 11.

[0044] In another setting form of this system, the cold energy recovery device 18 is replaced by an adsorption type air purifier 19, and at this time, the cold storage purifier 8 is replaced by a cold storage device 20.

[0045] In actual application, there is at least one cold storage purifier 8 and one heat accumulator 10. Multiple cold storage purifiers are connected in parallel, and multiple heat accumulators are connected in parallel.

[0046] This will be described below with specific embodiments.

[0047] Embodiment 1

[0048] As Figure 1, the system includes an air liquefaction device 1, a liquid air storage tank 2, a cryogenic booster pump 3, a first regulating valve 4, a second regulating valve 5, a third regulating valve 6, a fourth regulating valve 7, a cold storage purifier 8, a fifth regulating valve 9, a heat storage device 10, a waste heat exchanger 11, an expander 12, a generator 13, a hot blast stove 14, a waste heat pipeline 15, an air compressor 16, an air filter 17, and a cold energy recovery device 18.

[0049] In this system, the liquefied air energy storage device (air liquefaction device 1 and liquid air storage tank 2) is used to liquefy and store air using low-cost electric energy during off-peak electricity periods; the pressurized gasification and cold storage subsystem (cryogenic booster pump 3 and cold storage purifier 8) is used to pressurize, gasify, and recover and store cold energy of the stored liquid air during non-off-peak electricity periods; the waste heat recovery subsystem (heat storage device 10 and waste heat exchanger 11) is respectively used for the recovery and utilization of compression heat and industrial waste heat; the expansion power generation subsystem (expander 12 and generator 13) is used to drive the generator to generate electricity by the expander doing work on the pressurized and gasified air.

[0050] The specific working process is as follows:

[0051] S1. During off-peak electricity periods, the cryogenic booster pump 3, the first regulating valve 4, the fourth regulating valve 7, and the fifth regulating valve 9 are closed, and other valves are fully open. The air from the environment is filtered by the air filter 17 and then compressed in the air compressor 16, and then enters the inner pipeline of the heat storage device 10 to release heat and cool down, and then enters the cold storage purifier 8 through the cold energy recovery device 18 for purification and cold energy recovery, and then is divided into part A and part B. Among them, part A enters the air liquefaction device 1 to be liquefied and then enters the liquid air storage tank 2, and part B enters the heat storage device 10 to be heated after recovering cold energy through the inner pipeline of the cold energy recovery device 18, and enters the expander 12 to expand and do work after further heating in the waste heat exchanger 11 and then enters the hot blast stove 14 as blast furnace air. At the same time, the expander drives the generator 13 to generate electricity;

[0052] S2. At the end of the off-peak electricity period, the third regulating valve 6 and the second regulating valve 5 are closed, and the fourth regulating valve 7 is opened. The impurities such as moisture, carbon dioxide, and hydrocarbons frozen in the outlet thermocline of the cold storage purifier 8 during the off-peak electricity period are reheated and sublimated and removed and discharged through the fourth regulating valve 7. After the discharge is completed, the air compressor 16 and the fourth regulating valve 7 are closed;

[0053] S3. At the end of the off-peak electricity period and during non-off-peak electricity periods, the first regulating valve 4 and the fifth regulating valve 9 are opened, and other regulating valves are closed. The liquid air stored in the liquid air storage tank 2 during the off-peak electricity period is pressurized by the cryogenic booster pump 3, releases cold energy in the cold storage purifier 8, then enters the heat storage device 10 to be reheated, and further enters the expander 12 to expand and do work after heating in the waste heat exchanger 11 and then enters the hot blast stove 14 as blast furnace air. At the same time, the expander drives the generator 13 to generate electricity.

[0054] Generally, in step S1, part A is N times the mass flow rate of part B, where N ranges from 2 to 6; during the off-peak electricity period in step S3, the mass flow rates of part A and part B are zero.

[0055] Alternatively, during the valley electricity period, the above-mentioned steps S1 and S3 can be combined. At this time, regulating valve 1 4, regulating valve 3 6, and regulating valve 5 9 are opened, regulating valve 2 5 and regulating valve 4 7 are closed, and the low-temperature booster pump 3 operates; the air from the environment is filtered by the air filter 17 and then enters the air compressor 16 for compression, and then enters the inner pipeline of the regenerator 10 to release heat and cool down, and then enters the cold energy recovery device 18 and then enters the cold storage purifier 8 for purification and cold energy recovery, and then enters the air liquefaction device 1 for liquefaction and then enters the liquid air storage tank 2. The liquid air stored in the liquid air storage tank 2 during the valley electricity period is pressurized by the low-temperature booster pump 3, releases cold energy in the cold storage purifier 8, then enters the regenerator 10 for reheating, and is further heated in the waste heat exchanger 11 and then enters the expander 12 to expand and do work, and then enters the hot blast stove 14 as blast furnace air. At the same time, the expander 12 drives the generator 13 to generate electricity.

[0056] Embodiment 2

[0057] As Figure 2 shown, the system includes an air liquefaction device 1, a liquid air storage tank 2, a low-temperature booster pump 3, a regulating valve 1 4, a regulating valve 3 6, a regenerator 20, a regulating valve 5 9, a regenerator 10, a waste heat exchanger 11, an expander 12, a generator 13, a hot blast stove 14, a waste heat pipeline 15, an air compressor 16, an air filter 17, an air purifier 19, and a regulating valve 6 21.

[0058] In this system, the liquefied air energy storage device (air liquefaction device 1 and liquid air storage tank 2) is used to liquefy and store air using low-cost electric energy during the valley electricity period; the air purifier 19 is used to adsorb and remove impurities such as moisture, carbon dioxide, and hydrocarbons in the air before it enters the regenerator 20; the pressurized gasification and cold storage subsystem (low-temperature booster pump 3 and regenerator 20) is used to pressurize, gasify, and recover and store cold energy of the stored liquid air during the off-peak electricity period; the waste heat recovery subsystem (regenerator 10 and waste heat exchanger 11) is respectively used for the recovery and utilization of compression heat and industrial waste heat; the expansion power generation subsystem (expander 12 and generator 13) is used to drive the generator to generate electricity by the expander doing work on the pressurized and gasified air.

[0059] The specific working process is as follows:

[0060] S1. During the valley electricity period, the low-temperature booster pump 3, the first regulating valve 4 and the sixth regulating valve 21 are closed, and other valves are fully open. The air from the environment is filtered by the air filter 17 and then enters the air compressor 16 for compression. Then it enters the inner pipeline of the regenerator 10 to release heat and cool down, and then is divided into part C and part D after passing through the air purifier 19. Among them, part C enters the cold accumulator 20 to cool down and then enters the air liquefaction device 1 to be liquefied and then enters the liquid air storage tank 2. Part D passes through the regenerator 10, enters the waste heat exchanger 11 to be heated, then enters the expander 12 to expand and do work, drives the generator 13 to generate electricity, and then enters the hot blast stove 14 as the blast for the blast furnace. The mass flow ratio of part C to part D is 2:1 to 5:1;

[0061] S2. During the non-valley electricity period, the third regulating valve 6 and the sixth regulating valve 21 are closed, and other regulating valves are fully open. The liquid air stored in the liquid air storage tank 2 during the valley electricity period is pressurized by the low-temperature booster pump 3, releases cold in the cold accumulator 20, then enters the regenerator 10 for reheating, and is further heated in the waste heat exchanger 11 and then enters the expander 12 to expand and do work, drives the generator 13 to generate electricity, and then enters the hot blast stove 14 as the blast for the blast furnace.

[0062] S3. At the end of the valley electricity period, gradually close the third regulating valve 6 and gradually open the sixth regulating valve 21 for air discharge until the third regulating valve 6 is fully closed and the gas flow of part C is 0. Then gradually open the low-temperature booster pump 3 and the first regulating valve 4 and continue to open the sixth regulating valve 21. After the air leaving the cold accumulator 20 gradually replaces the air of part D, the sixth regulating valve 21 and the air compressor 16 are closed.

[0063] In the above two embodiments, the outlet pressure of the air compressor in step S1 is controlled to be 0.2 - 0.7 MPa.

[0064] In step S3 of embodiment 1 and step S2 of embodiment 2, the pressure of the liquid air leaving the low-temperature booster pump is 0.2 - 10 MPa; the moisture content of the air entering the hot blast stove is less than or equal to 10 ppm.

[0065] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A low-temperature energy storage and self-dehumidification blast furnace blast system, characterized in that: It includes liquefied air energy storage device, pressurized gasification and cold storage subsystem, waste heat recovery subsystem, expansion power generation subsystem, The liquefied air energy storage device comprises an air liquefaction device and a liquid air storage tank. The pressurized gasification and cold storage subsystem includes a low-temperature booster pump and a cold storage purifier. The waste heat recovery subsystem includes a heat accumulator and a waste heat heat exchanger. The expansion and power generation subsystem includes an expander and a generator. The outlet of the air liquefaction device is connected to the inlet of the liquid air storage tank through a pipeline, the outlet of the liquid air storage tank is connected to the low-temperature booster pump through a pipeline, a regulating valve 1 is arranged on the pipeline connecting the low-temperature booster pump and the cold storage purifier, the cold storage purifier is connected to the inlet of the air liquefaction device, and a regulating valve 3 is arranged on the pipeline connecting the cold storage purifier to the air liquefaction device, the other end of the cold storage purifier is connected to the heat accumulator and the cold recovery device, the outlet of the heat accumulator is connected to the waste heat heat exchanger, the outlet of the waste heat heat exchanger is connected to the expander, the expander drives the generator to generate electricity, and the outlet of the expander is connected to the hot air furnace; The inlet of the pipe in the heat accumulator is connected to the outlet of the air compressor, the inlet of the air compressor is connected to the outlet of the air filter, and the outlet of the pipe in the heat accumulator is connected to the cold recovery device.

2. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 1, characterized in that: A regulating valve 2 is arranged on the pipe connecting the cold storage purifier and the pipe inlet of the cold recovery device, and the pipe outlet of the cold recovery device is connected to the heat accumulator; a regulating valve 4 is arranged on the pipe leading to the external air environment from the cold storage purifier; a regulating valve 5 is arranged on the pipe connecting the cold storage purifier and the heat accumulator.

3. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 1, characterized in that: A waste heat pipeline is provided in the waste heat heat exchanger.

4. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 1, characterized in that: The cold recovery device is replaced by an adsorption air purifier, and the cold storage purifier is replaced by a cold storage device.

5. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 1, characterized in that: There are at least one cold storage purifier and one heat storage device, and a plurality of cold storage purifiers and a plurality of heat storage devices are connected in parallel.

6. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 1, characterized in that: The system works as follows: S1. During the valley power period, the low-temperature booster pump, regulating valve 1, regulating valve 4 and regulating valve 5 are closed, and other valves are fully opened. The air from the environment is filtered by the air filter and then enters the air compressor for compression, then enters the pipeline in the heat accumulator to release heat and cool down, and then enters the cold storage purifier for purification and cold recovery after passing through the cold recovery device, and then is divided into part A and part B. Part A enters the air liquefaction device for liquefaction and then enters the liquid air storage tank, and part B recovers cold through the pipeline in the cold recovery device and then enters the heat accumulator for heating, and after further heating in the waste heat heat exchanger, enters the expander for expansion and work, and then enters the hot blast furnace as blast furnace blast. At the same time, the expander drives the generator to generate electricity; S2. At the end of the valley power period, close the regulating valve 2 and regulating valve 3, open the regulating valve 4, and reheat and sublimate the water, carbon dioxide and hydrocarbon impurities frozen in the outlet temperature slope layer of the cold storage purifier during the valley power period through the regulating valve 4. After the release, close the air compressor and regulating valve 4; S3. At the end of the valley power period and the non-valley power period, regulating valve 1 and regulating valve 5 are opened, and other regulating valves are closed. The liquid air stored in the liquid air storage tank during the valley power period is pressurized by the low-temperature booster pump, releases cold in the cold storage purifier, and then enters the heat accumulator for reheating, and is further heated in the waste heat heat exchanger before entering the expander for expansion and work, and then enters the hot blast furnace as blast furnace blast. At the same time, the expander drives the generator to generate electricity.

7. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 6, characterized in that: When the cold recovery device is replaced by an air purifier, the pipeline of part B is omitted in step S1, and the moisture, carbon dioxide and hydrocarbon impurities in the cold storage purifier in step S2 have been purified and removed when passing through the air purifier.

8. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 6, characterized in that: In step S1, the mass flow rate of part A is N times that of part B, and the value of N is 2-6; in step S3, during the non-valley period, the mass flow rates of part A and part B are zero; The system changes the oxygen enrichment of liquid air by adjusting the air liquefaction rate of the air liquefaction device, thereby flexibly adapting to the blast furnace's requirements for blast oxygen enrichment. When the air liquefaction rate of the air liquefaction device is 82%-56%, the air supply oxygen enrichment is 1%-8%.

9. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 6, characterized in that: During the valley power period, the mixed mode of step S1 plus S3 is adopted, the regulating valve 1, regulating valve 3 and regulating valve 5 are opened, the regulating valve 2 and regulating valve 4 are closed, and the low-temperature booster pump is working; the air from the environment is filtered by the air filter and then enters the air compressor for compression, and then enters the pipeline in the heat accumulator to release heat and cool down, and then passes through the cold recovery device and enters the cold storage purifier for purification and cold recovery, and then enters the air liquefaction device for liquefaction and then enters the liquid air storage tank. The liquid air stored in the liquid air storage tank during the valley power period is pressurized by the low-temperature booster pump, releases cold in the cold storage purifier, and then enters the heat accumulator for reheating, and is further heated in the waste heat heat exchanger and then enters the expander to expand and do work, and then enters the hot blast furnace as blast furnace blast, and at the same time, the expander drives the generator to generate electricity.

10. The low-temperature energy storage and self-dehumidification blast furnace blast system according to claim 9, characterized in that: The outlet pressure of the air compressor is 0.2-0.7MPa; the pressure of the liquid air out of the low-temperature booster pump is 0.2-10MPa; the moisture content of the air entering the hot air furnace is less than or equal to 10ppm.

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