Low-carbon blast furnace top coal gas and blast furnace slag heat energy recycling and efficient utilization method and system

Abstract

The application discloses a kind of low-carbon blast furnace top coal gas and blast furnace slag heat energy recovery efficient utilization method and system, system includes cooling water pump, cooling and purification tower, slag flushing water tank, vacuum flash evaporator, induced draft fan, vacuum pump, steam liquid distributor, steam compressor, filter, hot water pump and top coal gas wet decarburization system etc.;Top coal gas is exchanged with cooling water by cooling and purification tower, and sensible heat and latent heat are recovered, steam and high-temperature hot water are generated after hot water slag flushing;Low-pressure steam is generated in vacuum flash evaporator by high-temperature hot water, and steam is supplied to wet decarburization system reboiler after upgrading by compressor;Condensate and unvaporized hot water are recycled to water slag system after heat recovery by wet decarburization system heater.The application not only can recover waste heat resource existing in low-carbon blast furnace system, but also can efficiently use by-product steam directly in top coal gas wet decarburization process, reduce operation cost of top coal gas wet decarburization system by more than 25%, and energy medium consumption in smelting process by more than 0.65 GJ / tFe.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology, and relates to a method and system for efficient recovery and utilization of low-carbon blast furnace top gas and blast furnace slag heat energy. Background Technology

[0002] The steel industry is a vital global industry, but also a major source of energy consumption and carbon dioxide emissions. China, as the world's largest steel producer, relies heavily on the blast furnace-converter long process, accounting for approximately 90% of its total steel production. During blast furnace ironmaking, the byproducts top gas and blast furnace slag contain abundant waste heat resources. Top gas typically contains carbon dioxide, carbon monoxide, hydrogen, nitrogen, and water vapor, and operates at high temperatures and pressures, exhibiting significant potential for sensible and latent heat recovery. Blast furnace slag, as a solid byproduct of ironmaking, carries a high amount of heat. However, traditional blast furnace processes have low utilization efficiency for these waste heat resources, leading to significant energy waste and environmental pollution. Developing efficient waste heat recovery technologies can not only improve the economic benefits of steel enterprises but also promote green and low-carbon development.

[0003] The wet decarbonization system for top gas is a key technology in low-carbon blast furnace processes, designed to capture carbon dioxide from top gas to reduce carbon emissions. Its working principle is based on chemical absorption, typically using amine solutions (such as monoethanolamine or methyldiethanolamine) as absorbents. In the absorption tower, the top gas and absorbent come into countercurrent contact, with carbon dioxide selectively absorbed to generate a CO2-rich absorbent liquid. This rich liquid is then sent to a desorption tower (or regeneration tower), where heating (usually using low-pressure steam) causes the absorbent to release CO2, generating high-purity CO2 gas. Simultaneously, the regenerated absorbent is recycled. The reboiler in the wet decarbonization system is its energy-intensive component, requiring a large amount of low-pressure steam. Wet decarbonization systems face multiple challenges in practical applications: First, the demand for steam is large, and traditional blast furnace systems cannot be self-sufficient, requiring additional purchases or combustion of fuel to produce steam, which increases operating costs; second, the heat source utilization efficiency of reboilers and heaters is low, and there is a lack of effective integration with blast furnace waste heat recovery systems; third, the wet decarbonization process generates a large amount of condensate and hot water, which, if discharged directly, not only wastes heat energy but also increases water consumption and environmental pressure.

[0004] With the development of low-carbon and energy-saving technologies in the steel industry, more and more waste energy recovery and utilization technologies have been widely used, achieving good energy-saving and cost-reduction results. However, enterprises' utilization of waste heat and energy is still at a low level, mainly reflected in two aspects: the depth of utilization of waste heat and energy resources and the effective utilization degree of recovered energy. How to effectively improve these two aspects is of great positive significance to the steel industry, which is facing the pressure of energy conservation, emission reduction, and a severe operating situation. Summary of the Invention

[0005] In view of this, the purpose of this invention is to solve the above problems and provide a method and system for efficient recovery and utilization of low-carbon blast furnace top gas and blast furnace slag heat energy. By optimizing the system and process flow, efficient recovery and recycling of waste heat can be achieved, thereby reducing energy consumption and carbon emissions.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A low-carbon blast furnace top gas and slag heat energy recovery and high-efficiency utilization system includes a cooling water pump, a cooling and purification tower, a slag flushing water tank, a vacuum flash evaporator, an induced draft fan, a vacuum pump, a steam separator, a steam compressor, a filter, a hot water pump, and a top gas wet decarbonization system.

[0008] The bottom inlet of the cooling and purification tower is connected to a low-carbon blast furnace dry dust removal system via a pipeline to receive top coal gas. The top inlet of the cooling and purification tower is connected to a cooling water pump via a pipeline to supply cooling water. The top coal gas and cooling water exchange heat in countercurrent contact inside the tower to recover the sensible heat of the top coal gas and the latent heat of the water. The top outlet of the cooling and purification tower is connected to a top coal gas wet decarbonization system via a pipeline to output purified top coal gas. The bottom hot water outlet of the cooling and purification tower is connected to a slag flushing water tank via a pipeline to transport hot water.

[0009] The hot water inlet of the slag flushing tank is connected to the hot water outlet at the bottom of the cooling and purification tower via a pipeline to receive hot water. The slag inlet of the slag flushing tank is connected to the blast furnace tapping plant via a pipeline to receive high-temperature blast furnace slag. The hot water and blast furnace slag exchange heat in the slag flushing tank, and the generated steam is transported to the steam inlet of the steam separator by an induced draft fan via a pipeline. The high-temperature hot water is transported to the hot water inlet of the vacuum flash evaporator via a pipeline. The vacuum flash evaporator operates in a vacuum environment. A vacuum environment is formed by connecting the vacuum pump's evacuation pipeline, so that the high-temperature hot water does not need to be reheated to generate low-pressure steam. The low-pressure steam is transported to another steam inlet of the steam separator via the output pipeline of the vacuum pump. The unvaporized hot water in the vacuum flash evaporator is connected to a filter via a pipeline. After filtration and purification, it is pressurized by a hot water pump and transported to the inlet of the decarbonization gas heater of the top coal gas wet decarbonization system via a pipeline.

[0010] The steam inlet of the steam separator is connected to the steam output pipe of the induced draft fan and the low-pressure steam output pipe of the vacuum pump through a pipeline, receiving steam from the slag flushing water tank and the vacuum flash evaporator. The top outlet of the steam separator is connected to the inlet of the steam compressor through a pipeline. The steam compressor compresses the low-pressure steam to increase its pressure and temperature. The outlet of the steam compressor is connected to the reboiler of the desorption tower of the wet decarbonization system of the top coal gas through a pipeline. The reboiler directly and efficiently utilizes the heat of the steam. The condensate produced by the reboiler of the decarbonization tower is used for the heater before the decarbonization gas expander. The outlet of the heater is connected to the inlet of the cooling water tower of the water slag system through a pipeline, and the cooling water is recycled.

[0011] Furthermore, it also includes an intelligent control system, which includes sensors for monitoring pressure, temperature and flow rate respectively installed on the steam distributor, vacuum flash evaporator, vacuum pump and steam compressor, as well as an AI algorithm module. The sensors are connected to the AI ​​algorithm module through signal lines to monitor the pressure, temperature and flow rate of steam and hot water in real time. The AI ​​algorithm module is connected to the control units of the vacuum pump and steam compressor through control lines to dynamically adjust their power to optimize system energy efficiency.

[0012] A method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy, based on the aforementioned efficient recovery and utilization system for low-carbon blast furnace top gas and slag heat energy, includes the following steps:

[0013] Top gas cooling and purification: The low-carbon blast furnace top gas self-drying dust removal system enters the bottom of the cooling and purification tower, and cooling water enters from the top of the tower. It contacts the top gas in a countercurrent manner to exchange heat, recovering the sensible heat of the top gas and the latent heat of the water. The cooled and purified top gas enters the downstream top gas pressure regulation and decarbonization process. The cooling water that has obtained the heat from the top gas is discharged from the bottom of the cooling and purification tower and sent directly to the slag flushing water tank for washing the blast furnace slag.

[0014] Hot water flushing and steam generation: The hot water discharged from the cooling and purification tower exchanges heat with the blast furnace slag in the flushing water tank to generate steam and high-temperature hot water. The steam is sent to the steam separator by the induced draft fan, and the high-temperature hot water is sent to the vacuum flash evaporator. The vacuum flash evaporator generates low-pressure steam in a vacuum environment without secondary heating of the high-temperature hot water. The low-pressure steam is transported to the steam separator by the vacuum pump. The unvaporized hot water is filtered and purified, and then pressurized by the hot water pump and sent to the decarbonization gas heater for direct use.

[0015] Steam upgrading: The steam separator receives steam delivered by the induced draft fan and vacuum pump, and the pressure and temperature of the low-pressure steam are increased by the steam compressor. The upgraded steam is used as the heating medium for the reboiler of the wet decarbonization system of top coal gas.

[0016] Steam and hot water utilization: The reboiler of the wet decarbonization system is heated by the upgraded steam, and the condensate generated is used as a heater before the decarbonization gas expander, and then sent to the cooling tower of the water slag system for recycling; the hot water pressurized by the hot water pump is sent to the decarbonization gas heater, and after recovering the heat, it is sent to the cooling tower of the water slag system for recycling.

[0017] Furthermore, sensors for monitoring pressure, temperature, and flow are installed in the steam distributor, vacuum flash evaporator, vacuum pump, and steam compressor. Combined with AI algorithms, the distribution of steam pressure, temperature, and flow is optimized in real time, and the power of the vacuum pump and steam compressor is dynamically adjusted to improve system energy efficiency.

[0018] Furthermore, the top coal gas is top coal gas treated by gravity and dry dust removal systems, with a temperature ≥120℃, pressure ≥150kPa, N2 content <10%, H2O content >10%, and CO2 content <40%.

[0019] Furthermore, the hot water discharged from the bottom of the top gas cooling and purification tower has a temperature ≥70℃ and a pressure ≥130kPa, and the temperature of the top gas after cooling and purification is ≤40℃.

[0020] Furthermore, the blast furnace slag carries ≥0.5GJ / tFe of heat, and the final temperature of the slag flushing water is ≤85℃.

[0021] Furthermore, the operating pressure of the vacuum flash evaporator is 20 kPa to 80 kPa; the outlet pressure of the vacuum pump and induced draft fan, as well as the operating pressure of the steam separator, are <10 kPa; and the outlet pressure of the hot water pump is ≥400 kPa.

[0022] Furthermore, the outlet pressure of the steam compressor is 120 kPa to 200 kPa, and the outlet temperature is ≤150℃.

[0023] Furthermore, the reboiler of the top coal gas wet decarbonization system requires 0.30-0.40 t / tCO2 of low-pressure steam, and the comprehensive CO2 capture energy consumption is ≤1.70 GJ / tCO2.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. High-efficiency waste heat recovery and system integration: This invention achieves comprehensive recovery of the sensible and latent heat of top gas and the heat from blast furnace slag through the integrated connection of a cooling purification tower, a slag flushing water tank, a vacuum flash evaporator, and a steam compressor. The cooling purification tower converts the sensible and latent heat of the top gas into hot water, which is directly used in the slag flushing water tank. The slag flushing water tank uses blast furnace slag to heat the hot water, generating steam and high-temperature hot water. The vacuum flash evaporator generates low-pressure steam, eliminating the need for secondary heating. Compared to traditional single-source heat recovery systems, this invention employs multi-stage heat energy utilization to improve the overall heat energy recovery rate, significantly reducing energy waste in ultra-low carbon blast furnace ironmaking.

[0026] 2. Significantly Reduced Costs of Wet Decarbonization: This invention upgrades low-pressure steam using a vacuum flash evaporator and steam compressor, directly meeting the reboiler requirements of the wet decarbonization system. Compared to traditional processes that rely on external steam, this system achieves steam self-sufficiency, reducing overall CO2 capture energy consumption to ≤1.50 GJ / tCO2. Simultaneously, pressurized hot water is used for the decarbonization gas heater, reducing external heat source requirements. Overall, this reduces the operating costs of the wet decarbonization system by approximately 25% and energy consumption by 0.667 GJ / tFe, ensuring the economic viability of low-carbon blast furnaces.

[0027] 3. Significant environmental benefits: This invention recovers water vapor from the top gas through a cooling purification tower, reducing water vapor emissions and water consumption. The hot water and condensate generated by the slag flushing water tank and vacuum flash evaporator are circulated to the cooling tower of the slag system, improving the utilization rate of circulating water and solving the wastewater discharge problem of traditional slag flushing processes.

[0028] 4. Intelligent Control for Optimized Energy Efficiency: This invention optimizes system operating parameters in real time by installing pressure, temperature, and flow sensors in the steam distributor, vacuum flash evaporator, vacuum pump, and steam compressor, combined with an AI algorithm module. The AI ​​algorithm dynamically adjusts the vacuum pump and steam compressor to ensure efficient distribution of steam and hot water, increasing the system's energy efficiency ratio to ≥25%. Compared to traditional fixed-parameter control, intelligent control can dynamically adjust based on fluctuations in top gas flow and composition, reducing energy consumption fluctuations and improving system stability.

[0029] 5. Economic and industrial applicability: This invention is designed for the characteristics of China's steel industry, which is dominated by coal and has low-grade iron ore. It optimizes the integration of ultra-low carbon blast furnace waste heat recovery and wet decarburization, and is suitable for long process of blast furnace-converter.

[0030] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0032] Figure 1 This is a schematic diagram of the efficient utilization system for low-carbon blast furnace top gas and slag heat energy recovery in this invention.

[0033] Figure reference numerals: 1-Cooling water pump; 2-Cooling purification tower; 3-Slag flushing water tank; 4-Vacuum flash evaporator; 5-Induced draft fan; 6-Vacuum pump; 7-Steam separator; 8-Steam compressor; 9-Filter; 10-Hot water pump; 11-Reboiler; 12-Decarbonization gas heater; 13-Pressure sensor; 14-Temperature sensor; 15-Flow sensor. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0035] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0036] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0037] Example 1

[0038] Please refer to Figure 1 This is a low-carbon blast furnace top gas and slag heat energy recovery and high-efficiency utilization system, including a cooling water pump 1, a cooling and purification tower 2, a slag flushing water tank 3, a vacuum flash evaporator 4, an induced draft fan 5, a vacuum pump 6, a steam separator 7, a steam compressor 8, a filter 9, a hot water pump 10, and a top gas wet decarbonization system.

[0039] The bottom inlet of the cooling purification tower 2 is connected to the low-carbon blast furnace dry dust removal system through a pipeline to receive the top coal gas. The top inlet of the cooling purification tower 2 is connected to the cooling water pump 1 through a pipeline to supply cooling water. The top coal gas and cooling water exchange heat in countercurrent contact inside the tower to recover the sensible heat of the top coal gas and the latent heat of the water. The top outlet of the cooling purification tower 2 is connected to the top coal gas wet decarbonization system through a pipeline to output the purified top coal gas. The bottom hot water outlet of the cooling purification tower 2 is connected to the slag flushing water tank 3 through a pipeline to transport hot water.

[0040] The hot water inlet of the slag flushing tank 3 is connected to the hot water outlet at the bottom of the cooling and purification tower 2 through a pipeline to receive hot water. The slag inlet of the slag flushing tank 3 is connected to the blast furnace tapping plant through a pipeline to receive high-temperature blast furnace slag. The hot water and blast furnace slag exchange heat in the slag flushing tank 3. The generated steam is transported to the steam inlet of the steam separator 7 through a pipeline by the induced draft fan 5. The high-temperature hot water is transported to the hot water inlet of the vacuum flash evaporator 4 through a pipeline. The vacuum flash evaporator 4 operates in a vacuum environment. A vacuum environment is formed by connecting the vacuum pump 6 through the evacuation pipeline, so that the high-temperature hot water does not need to be reheated to generate low-pressure steam. The low-pressure steam is transported to the other steam inlet of the steam separator 7 through the output pipeline of the vacuum pump 6. The unvaporized hot water in the vacuum flash evaporator 4 is connected to the filter 9 through a pipeline. After filtration and purification, it is pressurized by the hot water pump 10 and transported through a pipeline to the inlet of the decarbonization gas heater 12 of the top coal gas wet decarbonization system.

[0041] The steam inlet of the steam separator 7 is connected to the steam output pipe of the induced draft fan 5 and the low-pressure steam output pipe of the vacuum pump 6 through a pipeline, receiving steam from the slag flushing tank 3 and the vacuum flash evaporator 4. The top outlet of the steam separator 7 is connected to the inlet of the steam compressor 8 through a pipeline. The steam compressor 8 compresses the low-pressure steam to increase its pressure and temperature. The outlet of the steam compressor 8 is connected to the reboiler 11 of the desorption tower of the wet decarbonization system of the top coal gas through a pipeline, outputting upgraded steam. The condensate produced by the reboiler 11 is transported through a pipeline to the generated steam condensate to continue to be used in the heater before the decarbonization gas expander. The heater outlet is connected to the inlet of the cooling water tower of the water slag system through a pipeline, and the cooling water is recycled.

[0042] The system also includes an intelligent control system, which includes pressure sensors 13, temperature sensors 14, and flow sensors respectively installed on the steam distributor 7, vacuum flash evaporator 4, vacuum pump 6, and steam compressor 8, as well as an AI algorithm module. The pressure sensors 13, temperature sensors 14, and flow sensors are connected to the AI ​​algorithm module through signal lines to monitor the pressure, temperature, and flow of steam and hot water in real time. The AI ​​algorithm module is connected to the control units of vacuum pump 6 and steam compressor 8 through control lines to dynamically adjust their power to optimize system energy efficiency.

[0043] Example 2

[0044] The volume fractions of the low-carbon blast furnace top gas in this embodiment are as follows: carbon dioxide 30.0%, carbon monoxide 36.2%, hydrogen 16.1%, nitrogen 5.5%, and water 12.2%; the pressure is 220 kPa, the temperature is 150°C, and the flow rate is 251,000 Nm³. 3 / h.

[0045] A method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy, based on the aforementioned efficient recovery and utilization system for low-carbon blast furnace top gas and slag heat energy, includes the following steps:

[0046] Top gas cooling and purification: The low-carbon blast furnace top gas enters the bottom of the cooling and purification tower 2 via a self-drying dust removal system. Cooling water enters from the top of the tower and exchanges heat with the top gas in a counter-current manner, recovering the sensible heat of the top gas and the latent heat of the water. The cooled and purified top gas then enters the downstream top gas pressure regulation and decarbonization process. The cooling water, which has absorbed the heat from the top gas, is discharged from the bottom of the cooling and purification tower 2 and directly sent to the slag flushing water tank 3 for rinsing the blast furnace slag. The temperature of the hot water discharged from the bottom of the top gas cooling and purification tower 2 is controlled to be ≥70℃ and the pressure ≥130kPa. The temperature of the cooled top gas is ≤40℃.

[0047] Hot water flushing and steam preparation: The hot water discharged from the cooling and purification tower 2 exchanges heat with the blast furnace slag in the flushing water tank 3 to generate steam and high-temperature hot water. The steam is drawn out by the induced draft fan 5 and sent to the steam separator 7. The outlet pressure of the induced draft fan 5 is <10kPa. The high-temperature hot water is sent to the vacuum flash evaporator 4. The vacuum flash evaporator 4 operates under a vacuum environment with a controlled operating pressure of 20kPa to 80kPa, so that the high-temperature hot water does not need to be reheated to generate low-pressure steam. The low-pressure steam is delivered to the steam separator 7 by the vacuum pump 6. The unvaporized hot water is filtered and purified, and then pressurized by the hot water pump 10 and sent to the decarbonization gas heater 12 for direct use. The outlet pressure of the hot water pump 10 is controlled to be ≥400kPa, and the final temperature of the flushing water is ≤85℃.

[0048] Steam upgrading: Steam separator 7 receives steam delivered by induced draft fan 5 and vacuum pump 6, and compresses and increases the pressure and temperature of low-pressure steam through steam compressor 8. The outlet pressure of steam compressor 8 is controlled at 120kPa~200kPa and the outlet temperature is ≤150℃. The upgraded steam is directly used as the heating medium of reboiler 11 in top coal gas wet decarbonization system.

[0049] Steam and hot water utilization: The reboiler 11 of the wet decarbonization system is heated by the upgraded steam. The required low-pressure steam is 0.30-0.40 t / tCO2, and the comprehensive CO2 capture energy consumption is ≤1.50 GJ / tCO2. The condensate produced is sent to the decarbonization gas heater 12, and then sent to the cooling tower of the water slag system for recycling. The hot water pressurized by the hot water pump 10 is sent to the decarbonization gas heater 12. After heat recovery, it is sent to the cooling tower of the water slag system for recycling.

[0050] During operation, the pressure sensor 13, temperature sensor 14 and flow sensor, combined with AI algorithms, optimize the distribution of steam pressure, temperature and flow in real time, dynamically adjust the power of vacuum pump 6 and steam compressor 8, and improve system energy efficiency.

[0051] Example results:

[0052] 1) Cooling and purification of top coal gas

[0053] After cooling and purification, the top coal gas contains: 33.4% carbon dioxide, 40.3% carbon monoxide, 17.9% hydrogen, 6.2% nitrogen, and 2.2% water; the pressure is 200 kPa, the temperature is 40℃, and the flow rate is 225386 Nm³. 3 / h;

[0054] Cooling water consumption of cooling purification tower 2: 420t / h; hot water discharge of cooling purification tower 2: 438t / h, temperature 80℃, pressure 220kPa.

[0055] 2) Hot water flushing of slag and steam preparation

[0056] Low-pressure steam: 45t / h, temperature 140℃, pressure 150kPa; hot water: 390t / h, temperature 86℃, pressure 400kPa.

[0057] 3) Top gas wet decarbonization system

[0058] Decarbonization gas: carbon dioxide 0.90%, carbon monoxide 61.7%, hydrogen 27.5%, nitrogen 9.5%, water 0.4%, temperature 75℃, flow rate 146415 Nm³. 3 / h;

[0059] Desorbed gas: 94.1% carbon dioxide, 0.2% carbon monoxide, 5.7% water; temperature: 40℃; flow rate: 77549 Nm³. 3 / h.

[0060] As can be seen from the above embodiments:

[0061] 1. This invention utilizes the sensible heat and latent heat of moisture in the top gas of an ultra-low carbon blast furnace, as well as the waste heat carried by the blast furnace slag, to produce low-pressure steam. Combined with the requirements of the wet decarbonization process of top gas in the new ultra-low carbon blast furnace process, the waste heat resources existing in this system are completely recovered and converted into low-pressure steam and hot water. The low-pressure steam is used as the heating medium of the desorption tower reboiler 11 in the wet decarbonization process of top gas, and the hot water is used as the heating medium of the decarbonization gas heater 12. This not only reduces the operating cost of the wet decarbonization system of top gas by more than 25%, but also reduces the energy medium consumption of 0.667 GJ / tFe during the smelting process.

[0062] 2. This invention can solve the environmental problem of water vapor emission during the existing blast furnace slag flushing process, and can also solve the cost emission problem during the cooling process of top gas and recover the large amount of water carried by the top gas, thereby reducing the water consumption of ultra-low carbon blast furnaces.

[0063] 3. The steam produced by the ultra-low carbon blast furnace top gas and blast furnace slag waste heat resources can fully meet the steam consumption requirements of the top gas wet decarbonization system, realizing the self-sufficiency of steam energy in this blast furnace smelting system.

[0064] 4. The hot water produced by the present invention using waste heat resources can be used as the heating medium of the decarbonization gas heater 12 to provide waste heat to the decarbonization gas, thereby reducing the operating energy consumption of the decarbonization gas heater.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A low-carbon blast furnace top gas and slag heat energy recovery and high-efficiency utilization system, characterized in that: This includes cooling water pumps, cooling purification towers, slag flushing water tanks, vacuum flash evaporators, induced draft fans, vacuum pumps, steam separators, steam compressors, filters, hot water pumps, and a wet decarbonization system for top coal gas. The bottom inlet of the cooling and purification tower is connected to a low-carbon blast furnace dry dust removal system via a pipeline to receive top coal gas. The top inlet of the cooling and purification tower is connected to a cooling water pump via a pipeline to supply cooling water. The top coal gas and cooling water exchange heat in countercurrent contact inside the tower to recover the sensible heat of the top coal gas and the latent heat of the water. The top outlet of the cooling and purification tower is connected to a top coal gas wet decarbonization system via a pipeline to output purified top coal gas. The bottom hot water outlet of the cooling and purification tower is connected to a slag flushing water tank via a pipeline to transport hot water. The hot water inlet of the slag flushing tank is connected to the hot water outlet at the bottom of the cooling and purification tower via a pipeline to receive hot water. The slag inlet of the slag flushing tank is connected to the blast furnace tapping plant via a pipeline to receive high-temperature blast furnace slag. The hot water and blast furnace slag exchange heat in the slag flushing tank, and the generated steam is transported to the steam inlet of the steam separator by an induced draft fan via a pipeline. The high-temperature hot water is transported to the hot water inlet of the vacuum flash evaporator via a pipeline. The vacuum flash evaporator operates in a vacuum environment. A vacuum environment is formed by connecting the vacuum pump's evacuation pipeline, so that the high-temperature hot water does not need to be reheated to generate low-pressure steam. The low-pressure steam is transported to another steam inlet of the steam separator via the output pipeline of the vacuum pump. The unvaporized hot water in the vacuum flash evaporator is connected to a filter via a pipeline. After filtration and purification, it is pressurized by a hot water pump and transported to the inlet of the decarbonization gas heater of the top coal gas wet decarbonization system via a pipeline. The steam inlet of the steam separator is connected to the steam output pipe of the induced draft fan and the low-pressure steam output pipe of the vacuum pump through a pipeline, receiving steam from the slag flushing water tank and the vacuum flash evaporator. The top outlet of the steam separator is connected to the inlet of the steam compressor through a pipeline. The steam compressor compresses the low-pressure steam to increase its pressure and temperature. The outlet of the steam compressor is connected to the reboiler of the desorption tower of the wet decarbonization system of the top coal gas through a pipeline. The reboiler directly and efficiently utilizes the heat of the steam. The condensate produced by the reboiler of the decarbonization tower is used for the heater before the decarbonization gas expander. The outlet of the heater is connected to the inlet of the cooling water tower of the water slag system through a pipeline, and the cooling water is recycled.

2. The low-carbon blast furnace top gas and slag heat energy recovery and high-efficiency utilization system according to claim 1, characterized in that: It also includes an intelligent control system, which includes sensors for monitoring pressure, temperature and flow rate respectively installed on the steam distributor, vacuum flash evaporator, vacuum pump and steam compressor, as well as an AI algorithm module. The sensors are connected to the AI ​​algorithm module through signal lines to monitor the pressure, temperature and flow rate of steam and hot water in real time. The AI ​​algorithm module is connected to the control unit of the vacuum pump and steam compressor through control lines to dynamically adjust their power to optimize system energy efficiency.

3. A method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy, characterized in that, The low-carbon blast furnace top gas and slag heat energy recovery and high-efficiency utilization system based on claim 1 or 2 includes the following steps: Top gas cooling and purification: The low-carbon blast furnace top gas self-drying dust removal system enters the bottom of the cooling and purification tower, and cooling water enters from the top of the tower. It contacts the top gas in a countercurrent manner to exchange heat, recovering the sensible heat of the top gas and the latent heat of the water. The cooled and purified top gas enters the downstream top gas pressure regulation and decarbonization process. The cooling water that has obtained the heat from the top gas is discharged from the bottom of the cooling and purification tower and sent directly to the slag flushing water tank for washing the blast furnace slag. Hot water flushing and steam generation: The hot water discharged from the cooling and purification tower exchanges heat with the blast furnace slag in the flushing water tank to generate steam and high-temperature hot water. The steam is sent to the steam separator by the induced draft fan, and the high-temperature hot water is sent to the vacuum flash evaporator. The vacuum flash evaporator generates low-pressure steam in a vacuum environment without secondary heating of the high-temperature hot water. The low-pressure steam is transported to the steam separator by the vacuum pump. The unvaporized hot water is filtered and purified, and then pressurized by the hot water pump and sent to the decarbonization gas heater for direct use. Steam upgrading: The steam separator receives steam delivered by the induced draft fan and vacuum pump, and the pressure and temperature of the low-pressure steam are increased by the steam compressor. The upgraded steam is used as the heating medium for the reboiler of the wet decarbonization system of top coal gas. Steam and hot water utilization: The reboiler of the wet decarbonization system is heated by the upgraded steam, and the condensate produced is sent to the decarbonization gas heater, and then sent to the cooling tower of the water slag system for recycling; the hot water pressurized by the hot water pump is sent to the decarbonization gas heater, and after heat recovery, it is sent to the cooling tower of the water slag system for recycling.

4. The method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy according to claim 3, characterized in that: Sensors for monitoring pressure, temperature, and flow are installed in the steam distributor, vacuum flash evaporator, vacuum pump, and steam compressor. Combined with AI algorithms, the steam pressure, temperature, and flow distribution are optimized in real time, and the power of the vacuum pump and steam compressor is dynamically adjusted to improve system energy efficiency.

5. The method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy according to claim 3, characterized in that: The top coal gas is top coal gas treated by gravity and dry dust removal systems. The temperature of the top coal gas is ≥120℃, the pressure is ≥150kPa, the N2 content is <10%, the H2O content is >10%, and the CO2 content is <40%.

6. The method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy according to claim 3, characterized in that: The hot water discharged from the bottom of the top gas cooling and purification tower has a temperature ≥70℃ and a pressure ≥130kPa, and the temperature of the top gas after cooling and purification is ≤40℃.

7. The method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy according to claim 3, characterized in that: The blast furnace slag carries a heat of ≥0.5GJ / tFe, and the final temperature of the slag flushing water is ≤85℃.

8. The method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy according to claim 3, characterized in that: The vacuum flash evaporator operates at a pressure of 20 kPa to 80 kPa; the outlet pressure of the vacuum pump and induced draft fan, as well as the operating pressure of the steam separator, are <10 kPa; the outlet pressure of the hot water pump is ≥400 kPa.

9. The method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy according to claim 3, characterized in that: The steam compressor has an outlet pressure of 120 kPa to 200 kPa and an outlet temperature of ≤150℃.

10. The method for efficient recovery and utilization of low-carbon blast furnace top gas and slag heat energy according to claim 3, characterized in that: The reboiler of the top coal gas wet decarbonization system requires 0.30-0.40 t / tCO2 of low-pressure steam, and the comprehensive CO2 capture energy consumption is ≤1.70 GJ / tCO2.

Images