A carbon dioxide capture and utilization system integrated with a steel plant and a method of using the same

Abstract

The present invention discloses a carbon dioxide capture and utilization system integrated with a steel plant and a method for using the system, comprising a regeneration tower, wherein the CO2 gas at the top of the regeneration tower is introduced into the lower end of a cooling tower, the gas outlet at the top of the cooling tower is connected to the inlet of a carbon dioxide compressor, the outlet of the carbon dioxide compressor is divided into two paths, one path is connected to the CO2 gas inlet of a liquefier, and the other path is connected to a buffer tank, the top outlet of the buffer tank is connected to the inlet of a valve station, and the outlet of the valve station is connected to the bottom of a converter, the carbon dioxide capture technology is combined with the utilization technology, the carbon dioxide captured from the flue gas of a coal-fired boiler or blast furnace gas in the steel plant is pressurized by a compressor, and then divided into two paths after pressurization, one path is directly sent to the converter for blowing of steel materials such as carbon steel or stainless steel to replace part of the argon gas, which can not only reduce the cost of this part of the gas, but also is expected to greatly reduce the purchase cost of the remaining part of the argon gas, the other path is cooled and liquefied and stored in a CO2 storage tank, and the liquid CO2 in the storage tank can be used for peak-shaving of steel blowing gas on the one hand.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture, utilization and storage, and in particular relates to a carbon dioxide capture and utilization system integrated with a steel plant and a method of using the system. Background Art

[0002] Global climate change has become a hot topic of international concern. As a comprehensive approach to address climate change and coordinate social and economic development, low-carbon development provides new opportunities for addressing climate change. China produces about 600 million tons of steel annually. Based on the CO2 emissions of 2.3 tons per ton of steel, the total emissions reach 1.38 billion tons, making it a major CO2 emitter, accounting for about 16% of the country's total industrial emissions. In the context of increasingly stringent global carbon emission controls, vigorously developing low-carbon technologies in the steel industry and promoting their application are effective ways for the steel industry to achieve low-carbon development and ensure green and sustainable development.

[0003] At present, steel mills use argon for blowing, part of which comes from the air separation system and the other part from the market. Using low-cost CO2 to replace part of the high-cost argon as the stirring gas source, reaction medium and protective gas source in the steelmaking process is an effective means to reduce CO2 emissions, achieve energy conservation and consumption reduction in the steelmaking process, and improve the quality of molten steel. Significant research progress has been made. However, the CO2 gas source used by steel mills is mostly purchased low-temperature liquid industrial carbon dioxide, which is not only costly, but also needs to be pressurized and heated before use, consumes a lot of heat energy, and is disturbed by the continuity of external supply, affecting the long-term stable production of steel mills. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a carbon dioxide capture and utilization system integrated with a steel plant and a method of using the same, which is particularly suitable for capturing low-concentration carbon dioxide in flue gas generated by coal-fired boiler flue gas, blast furnace gas, etc., and recovering the carbon dioxide while using it as bottom blowing gas for the converter, so as to reduce the carbon dioxide emissions from the steel plant and reduce the gas cost of the blowing system.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a carbon dioxide capture and utilization system integrated with a steel plant, comprising a regeneration tower, wherein the CO2 gas at the top of the regeneration tower is introduced into the lower end of a cooling tower, and the gas outlet at the top of the cooling tower is connected to the inlet of a carbon dioxide compressor, and the outlet of the carbon dioxide compressor is divided into two paths, one path is connected to the CO2 gas inlet of a liquefier, and the other path is connected to a buffer tank, and the top outlet of the buffer tank is connected to the inlet of a valve station, and the outlet of the valve station is connected to the bottom of a converter.

[0006] Furthermore, the CO2 liquid outlet of the liquefier is connected to the CO2 storage tank inlet, the CO2 storage tank outlet is connected to the booster pump inlet, the booster pump outlet is divided into two paths, one path goes to the liquid CO2 tank truck, and the other path is connected to the liquid CO2 inlet of the gasifier, the gas CO2 outlet of the gasifier is connected to the buffer tank, and the cold end of the gasifier goes to the condensate tank.

[0007] Furthermore, the lower section of the regeneration tower is connected to a reboiler, the steam inlet of the reboiler is connected to a low-pressure steam pipeline from a steam network, the condensate outlet of the reboiler is divided into two paths, one path goes to a condensate tank in the plant area, and the other path is connected to a hot end of a gasifier, the solution inlet of the reboiler is connected to the middle section of the regeneration tower, and the solution outlet of the reboiler is connected to the lower section of the regeneration tower.

[0008] Furthermore, the cooling tower is divided into two sections, the liquid outlet of the lower section is connected to the inlet of the water washing pump, one end of the water washing pump outlet is connected to the hot end of the water cooler, and the other end is connected to the upper end of the regeneration tower, the cold end of the water cooler is connected to the liquid inlet of the lower section of the cooling tower, the liquid outlet of the upper section of the cooling tower is connected to the inlet of the ammonia cooling pump, the ammonia cooling pump outlet is connected to the hot end of the ammonia cooler, and the cold end of the ammonia cooler is connected to the liquid inlet of the upper section of the cooling tower.

[0009] Furthermore, the cold source of the ammonia cooler is provided by an ammonia compressor, the cold source inlet of the ammonia cooler is connected to the outlet of the ammonia compressor, and the cold source outlet of the ammonia cooler is connected to the inlet of the ammonia compressor.

[0010] Furthermore, the cold source of the liquefier is provided by an ammonia compressor, the cold source inlet of the liquefier is connected to the outlet of the ammonia compressor, and the cold source outlet of the liquefier is connected to the inlet of the ammonia compressor.

[0011] Furthermore, a demister is provided at the top of the regeneration tower.

[0012] The present invention also provides a method for using a carbon dioxide capture and utilization system integrated with a steel plant, wherein a rich liquid that has absorbed CO2 in the flue gas of a coal-fired boiler or blast furnace gas is introduced into a packing layer at the upper end of a regeneration tower for desorption and regeneration, and the semi-lean liquid after desorption enters a reboiler from the middle section of the regeneration tower and is heated to 110°C. The heat source of the reboiler is low-pressure steam, and the condensate outlet of the reboiler is divided into two paths, one path goes to a condensate tank in the plant area, and the other path provides a heat source for a gasifier. The lean liquid after heating and regeneration passes from the bottom of the regeneration tower to the upper end of the absorption tower, and the absorption solvent is recycled;

[0013] The CO2 gas at the top of the regeneration tower enters the cooling tower for cooling through the demister. The cooling tower is divided into two sections, the lower section uses the circulating cooling water of the plant area as the cold source. The CO2 gas enters the upper section of the cooling tower after being cooled to 40°C. The lower section uses liquid ammonia as the cold source. The CO2 gas enters the carbon dioxide compressor after being cooled to 5°C.

[0014] After the gaseous CO2 is pressurized to 3Mpa by the carbon dioxide compressor, it is divided into two paths. One path of gaseous CO2 enters the buffer tank. The CO2 gas coming out of the buffer tank goes to the valve station. After the flow and pressure are adjusted by the valve station, it goes to the bottom of the converter for bottom blowing in steelmaking. The other path of gaseous CO2 goes to the liquefier, and after being liquefied by the liquefier, it goes to the booster pump.

[0015] The booster pump outlet is divided into two routes, one goes to the liquid CO2 tanker for selling liquid CO2 products, and the other is connected to the liquid CO2 inlet of the gasifier. The gasified gas CO2 goes to the buffer tank for peak regulation of steel blowing gas.

[0016] The ammonia compressor provides cooling source for the ammonia cooler and liquefier.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: the present invention combines carbon dioxide capture technology with utilization technology, and the carbon dioxide captured from the flue gas of the coal-fired boiler or the blast furnace gas of the steel plant is pressurized by a compressor, and then divided into two paths after pressurization. One path is directly sent to the converter for blowing of steel such as carbon steel or stainless steel, replacing part of the argon gas, which can not only reduce the cost of this part of the gas, but also is expected to greatly reduce the purchase cost of the remaining part of the argon gas. The other path is cooled and liquefied and stored in the CO2 storage tank. The liquid CO2 in the storage tank can be used for peak regulation of steel blowing gas on the one hand, and can be sold on the other hand, which can achieve CO2 emission reduction and resource utilization while obtaining dual economic benefits. The present invention also effectively utilizes steam at multiple levels. The low-pressure steam drawn from the steam main pipeline of the plant is used to heat the rich liquid in the reboiler. The low-pressure steam is connected to the hot end of the gasifier and can be used to heat the liquid CO2 in the gasifier. While fully utilizing the heat of steam, the cooling water consumption for cooling the steam condensate is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention.

[0019] Among them, 1 is a regeneration tower, 2 is a demister, 3 is a reboiler, 4 is a cooling tower, 5 is an ammonia cooler, 6 is an ammonia cooling pump, 7 is a water cooling pump, 8 is a water cooler, 9 is a carbon dioxide compressor, 10 is a buffer tank, 11 is a valve station, 12 is a converter, 13 is an ammonia compressor, 14 is a liquefier, 15 is a CO2 storage tank, 16 is a booster pump, and 17 is a gasifier. DETAILED DESCRIPTION

[0020] The present invention will be described in more detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] like Figure 1As shown, a carbon dioxide capture and utilization system integrated with a steel plant of the present invention comprises a reboiler 3 connected to the lower section of a regeneration tower 1, the steam inlet of the reboiler 3 is connected to a low-pressure steam pipeline from a steam network, the condensate outlet of the reboiler 3 is divided into two paths, one path goes to a condensate tank in the plant area, and the other path is connected to a hot end of a gasifier 17, the solution inlet of the reboiler 3 is connected to the middle section of the regeneration tower 1, and the solution outlet of the reboiler 3 is connected to the lower section of the regeneration tower 1; a demister 2 is provided at the top of the regeneration tower 1, the CO2 gas at the top of the regeneration tower 1 is connected to the lower end of a cooling tower 4, the gas outlet at the top of the cooling tower 4 is connected to the inlet of a carbon dioxide compressor 9, the outlet of the carbon dioxide compressor 9 is divided into two paths, one path is connected to the CO2 gas inlet of a liquefier 14, and the other path is connected to a buffer tank 10, the top outlet of the buffer tank 10 is connected to the inlet of a valve station 11, and the outlet of the valve station 11 is connected to the bottom of a converter 12;

[0022] The cooling tower 4 is divided into two sections, the lower section liquid outlet is connected to the water washing pump 7 inlet, one end of the water washing pump 7 outlet is connected to the hot end of the water cooler 8, and the other end is connected to the upper end of the regeneration tower 1, the cold end of the water cooler 8 is connected to the liquid inlet of the lower section of the cooling tower 4, the upper section liquid outlet of the cooling tower 4 is connected to the inlet of the ammonia cooling pump 6, the outlet of the ammonia cooling pump 6 is connected to the hot end of the ammonia cooler 5, and the cold end of the ammonia cooler 5 is connected to the liquid inlet of the upper section of the cooling tower 4; the cold source of the ammonia cooler 5 is provided by the ammonia compressor 13, the cold source inlet of the ammonia cooler 5 is connected to the outlet of the ammonia compressor 13, and the cold source outlet of the ammonia cooler 5 is connected to the inlet of the ammonia compressor 13 The cold source of the liquefier 14 is provided by the ammonia compressor 13, the cold source inlet of the liquefier 14 is connected to the outlet of the ammonia compressor 13, and the cold source outlet of the liquefier 14 is connected to the inlet of the ammonia compressor 13; the CO2 liquid outlet of the liquefier 14 is connected to the inlet of the CO2 storage tank 15, the outlet of the CO2 storage tank 15 is connected to the inlet of the booster pump 16, and the outlet of the booster pump 16 is divided into two paths, one path goes to the liquid CO2 tank truck, and the other path is connected to the liquid CO2 inlet of the vaporizer 17, the gas CO2 outlet of the vaporizer 17 is connected to the buffer tank 10, and the cold end of the vaporizer 17 goes to the condensate tank.

[0023] The process and principle of the present invention are:

[0024] The rich liquid that has absorbed CO2 in the flue gas of coal-fired boilers or blast furnace gas enters the packing layer at the upper end of the regeneration tower 1 for desorption and regeneration. The CO2 gas obtained by desorption and regeneration enters the top of the regeneration tower 1. The semi-lean liquid after desorption enters the reboiler 3 from the middle section of the regeneration tower 1 and is heated to 110°C. The heat source of the reboiler 3 is low-pressure steam. The condensate outlet of the reboiler 3 is divided into two paths, one path goes to the condensate tank in the plant area, and the other path provides heat source for the gasifier 17. The lean liquid after heating and regeneration passes from the bottom of the regeneration tower 1 to the upper end of the absorption tower, and the absorption solvent is recycled.

[0025] The CO2 gas at the top of the regeneration tower 1 enters the cooling tower 4 for cooling through the demister 2. The cooling tower 4 is divided into two sections, the lower section adopts the circulating cooling water of the plant as the cold source. The CO2 gas enters the upper section of the cooling tower 4 after being cooled to 40°C. The lower section adopts liquid ammonia as the cold source. The CO2 gas enters the carbon dioxide compressor 9 after being cooled to 5°C.

[0026] The gaseous CO2 is pressurized to 3Mpa by the carbon dioxide compressor 9 and is divided into two paths. One path of the gaseous CO2 enters the buffer tank 10. The CO2 gas coming out of the buffer tank 10 is directed to the valve station 11. After the flow rate and pressure are adjusted by the valve station, the CO2 gas is directed to the bottom of the converter 12 for bottom blowing in steelmaking. The other path of the gaseous CO2 goes to the liquefier 14. After being liquefied by the liquefier 14, it goes to the booster pump 16.

[0027] The outlet of the booster pump 16 is divided into two routes, one route goes to the liquid CO2 tank truck for selling liquid CO2 products, and the other route is connected to the liquid CO2 inlet of the gasifier 17. The gasified gas CO2 goes to the buffer tank 10 for steel blowing gas peak regulation.

[0028] The ammonia compressor 13 provides a cold source for the ammonia cooler 5 and the liquefier 14 at the same time.

[0029] The system effectively combines carbon dioxide capture technology with utilization technology. The carbon dioxide product captured from coal-fired boiler flue gas or blast furnace gas is pressurized and divided into two paths. One path is directly sent to the converter for the blowing of steel such as carbon steel or stainless steel, replacing part of the argon gas. It can not only reduce the cost of this part of the gas, but also is expected to greatly reduce the procurement cost of the remaining argon gas. The other path is cooled and liquefied and stored in a CO2 storage tank. The liquid CO2 in the storage tank can be used for steel blowing gas peak regulation on the one hand, and can be used for sales on the other hand, which can achieve CO2 emission reduction and resource utilization while obtaining dual economic benefits.

Claims

1. A carbon dioxide capture and utilization system integrated with a steel plant, characterized in that: It comprises a regeneration tower (1), wherein the CO2 gas at the top of the regeneration tower (1) is introduced into the lower end of a cooling tower (4), the gas outlet at the top of the cooling tower (4) is connected to the inlet of a carbon dioxide compressor (9), the outlet of the carbon dioxide compressor (9) is divided into two paths, one path is connected to the CO2 gas inlet of a liquefier (14), and the other path is connected to a buffer tank (10), the top outlet of the buffer tank (10) is connected to the inlet of a valve station (11), and the outlet of the valve station (11) is connected to the bottom of a converter (12); The CO2 liquid outlet of the liquefier (14) is connected to the inlet of the CO2 storage tank (15), the outlet of the CO2 storage tank (15) is connected to the inlet of the booster pump (16), the outlet of the booster pump (16) is divided into two paths, one path goes to the liquid CO2 tank truck, and the other path is connected to the liquid CO2 inlet of the gasifier (17), the gas CO2 outlet of the gasifier (17) is connected to the buffer tank (10), and the cold end of the gasifier (17) goes to the condensate tank; The lower section of the regeneration tower (1) is connected to a reboiler (3). The steam inlet of the reboiler (3) is connected to a low-pressure steam pipeline from a steam network. The condensate outlet of the reboiler (3) is divided into two paths, one path goes to a condensate tank in the plant area, and the other path is connected to the hot end of the vaporizer (17). The solution inlet of the reboiler (3) is connected to the middle section of the regeneration tower (1). The solution outlet of the reboiler (3) is connected to the lower section of the regeneration tower (1). The cooling tower (4) is divided into upper and lower sections. The liquid outlet of the lower section is connected to the inlet of a water washing pump (7). One end of the outlet of the water washing pump (7) is connected to the hot end of a water cooler (8), and the other end is connected to the upper end of the regeneration tower (1). The cold end of the water cooler (8) is connected to the liquid inlet of the lower section of the cooling tower (4). The liquid outlet of the upper section of the cooling tower (4) is connected to the inlet of an ammonia cooling pump (6). The outlet of the ammonia cooling pump (6) is connected to the hot end of an ammonia cooler (5), and the cold end of the ammonia cooler (5) is connected to the liquid inlet of the upper section of the cooling tower (4).

2. A carbon dioxide capture and utilization system integrated with a steel plant according to claim 1, characterized in that: The cold source of the ammonia cooler (5) is provided by the ammonia compressor (13); the cold source inlet of the ammonia cooler (5) is connected to the outlet of the ammonia compressor (13); and the cold source outlet of the ammonia cooler (5) is connected to the inlet of the ammonia compressor (13).

3. The carbon dioxide capture and utilization system integrated with a steel plant according to claim 1, characterized in that: The cold source of the liquefier (14) is provided by the ammonia compressor (13); the cold source inlet of the liquefier (14) is connected to the outlet of the ammonia compressor (13); and the cold source outlet of the liquefier (14) is connected to the inlet of the ammonia compressor (13).

4. The carbon dioxide capture and utilization system integrated with a steel plant according to claim 1, characterized in that: A demister (2) is provided on the top of the regeneration tower (1).

5. A method for using a carbon dioxide capture and utilization system integrated with a steel plant according to any one of claims 1 to 4, characterized in that: The rich liquid that has absorbed CO2 in the flue gas of a coal-fired boiler or the blast furnace gas is introduced into the packing layer at the upper end of the regeneration tower (1) for desorption and regeneration. The semi-lean liquid after desorption enters the reboiler (3) from the middle section of the regeneration tower (1) and is heated to 110°C. The heat source of the reboiler (3) is low-pressure steam. The condensate outlet of the reboiler (3) is divided into two paths, one path goes to the condensate tank in the plant area, and the other path provides heat source for the gasifier (17). The lean liquid after heating and regeneration is passed from the bottom of the regeneration tower (1) to the upper end of the absorption tower, and the absorption solvent is recycled; The CO2 gas at the top of the regeneration tower (1) enters the cooling tower (4) for cooling through the demister (2). The cooling tower (4) is divided into an upper and lower section. The cooling source of the lower section adopts the circulating cooling water of the plant area. After the CO2 gas is cooled to 40° C., it enters the upper section of the cooling tower (4). The cooling source of the lower section adopts liquid ammonia. After the CO2 gas is cooled to 5° C., it enters the carbon dioxide compressor (9). The gaseous CO2 is pressurized to 3 MPa by the carbon dioxide compressor (9) and is divided into two paths. One path of the gaseous CO2 enters the buffer tank (10). The CO2 gas from the buffer tank (10) is directed to the valve station (11). After the flow rate and pressure are adjusted by the valve station (11), the CO2 gas is directed to the bottom of the converter (12) for bottom blowing in steelmaking. The other path of the gaseous CO2 goes to the liquefier (14). After being liquefied by the liquefier (14), the CO2 gas goes to the booster pump (16). The outlet of the booster pump (16) is divided into two routes, one route goes to a liquid CO2 tanker for selling liquid CO2 products, and the other route is connected to the liquid CO2 inlet of the gasifier (17). The gasified gaseous CO2 goes to the buffer tank (10) for peak regulation of steel blowing gas.

6. The method for using a carbon dioxide capture and utilization system integrated with a steel plant according to claim 5, characterized in that: The ammonia compressor (13) provides a cold source for the ammonia cooler (5) and the liquefier (14).

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