Energy efficiency improvement and cost control method for hydrogen-rich carbon circulating oxygen blast furnace system

Abstract

The invention relates to the technical field of blast furnace ironmaking, and particularly discloses an energy efficiency improvement and cost control method for a hydrogen-rich carbon circulating oxygen blast furnace system. Aiming at the problems of high decarburization energy consumption, insufficient equipment operation efficiency and high maintenance cost of the existing HyCROF system, five core measures of low-grade waste heat gradient utilization, regeneration gas cooling system transformation, decarburization compressor efficiency optimization, amine liquid system intelligent management and control and cost closed-loop early warning are cooperatively implemented; the system energy consumption is obviously reduced, and the operation cost is accurately controlled. According to the method, the cost of molten iron can be reduced by 40-50 yuan / ton, the cost difference between the method and a traditional blast furnace is greatly reduced, meanwhile, the system operation stability and the resource recycling rate are improved, key support is provided for commercialized popularization of the HyCROF technology, and the method is suitable for hydrogen-rich carbon circulating oxygen blast furnace systems of various scales.

Description

Technical Field

[0001] This invention relates to the field of blast furnace ironmaking technology, and in particular to a method for improving energy efficiency and controlling cost of a hydrogen-rich carbon-circulating oxygen blast furnace system. Background Technology

[0002] Hydrogen-rich carbon-recycled oxygen blast furnace (HyCROF) technology is one of the core pathways for the low-carbon transformation of the steel industry, offering significant advantages in reducing carbon emissions. However, during demonstration operations, this technology has revealed prominent economic issues, becoming a key obstacle to its large-scale commercialization. Taking a 2500m³ HyCROF blast furnace as an example, its iron production cost is approximately RMB 157.6 / ton higher than that of a traditional blast furnace, primarily due to the excessively high energy consumption of the decarbonization system. The energy consumption of the HyCROF system is mainly concentrated in two key areas: first, the decarbonization system, where the amine regeneration process consumes a large amount of high-quality steam, and the gas compression process consumes a large amount of electricity; second, the gas heating system, which requires the combustion of some gas to heat the decarbonized gas to a high temperature. Furthermore, the shortened lifespan of some key equipment (such as tuyeres) under the new process further increases equipment maintenance costs.

[0003] Existing decarbonization technologies originate from the chemical industry, and their direct application to the steelmaking process presents an energy efficiency mismatch problem: on the one hand, amine liquid regeneration typically relies on medium-pressure steam, which has high quality requirements and is expensive, while steel companies have a large amount of low-grade waste heat resources that are not effectively utilized; on the other hand, traditional regeneration gas cooling systems have large pressure drops, which increases the operating load of downstream compressors, and the operating efficiency of compressors needs to be further improved.

[0004] Therefore, there is an urgent need to develop a set of energy efficiency improvement and cost control methods tailored to the characteristics of HyCROF systems. Through comprehensive measures such as system optimization, waste heat utilization, and equipment improvement, operating costs can be significantly reduced, the cost gap with traditional processes can be narrowed, and obstacles can be removed for the commercial application of HyCROF technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving the energy efficiency and controlling the cost of a hydrogen-rich carbon-circulating oxygen blast furnace system, so as to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the basic solution provided by this invention is: a method for improving energy efficiency and controlling cost of a hydrogen-rich carbon-circulating oxygen blast furnace system, comprising the following synergistically implemented technical measures: Measure 1: Low-grade waste heat is used for amine regeneration: Low-temperature waste gas of 85-120℃ generated by the sintering ring cooler of the steel plant is collected and heated to above 90℃ through a heat recovery system consisting of a waste gas collection hood, a circulating fan, a soft water circulation loop and a plate heat exchanger. This soft water is then used as a heat medium to enter the reboiler of the amine regeneration tower in the decarbonization system, replacing the original 0.5-0.8MPa saturated steam heating of lean amine liquid to desorb CO2. Measure 2: Upgrade of the high-efficiency desorption regenerated gas spray cooling system: Replace the traditional shell-and-tube regenerated gas cooler with a direct contact spray cooling tower. The high-temperature regenerated gas and the spray cooling water directly contact each other for heat and mass transfer, reducing the total pressure difference of the regenerated gas system from 30 kPa to below 5 kPa. Measure 3: Improve the efficiency of decarbonized compressors: Add a plate heat exchanger in parallel to the liquid injection cooling circuit of the screw compressor, and use the 28-32℃ factory circulating cooling water to reduce the temperature of the liquid injection water from 45℃ to about 33℃, thereby improving the isothermal efficiency of the compressor. Measure 4: Optimization and intelligent control of the amine solution system: Control the amine solution concentration at 28%-32%, stabilize the pH value at 10.5-11.5, and scientifically add corrosion inhibitors and defoamers; upgrade the control system, add online monitoring equipment and big data fault early warning models to achieve preventive maintenance; Measure 5: Iron cost accounting and early warning mechanism: Regularly calculate the iron cost of HyCROF mode and traditional mode. When the cost deficit exceeds the set threshold, an early warning is triggered, and optimization measures are initiated to form a closed-loop management.

[0007] Furthermore, in the first measure, the low-temperature exhaust gas originates from the third and fourth sections of the sintering ring cooler, with a temperature range of 90-110℃. The heat recovery system is a closed-loop soft water circulation system, and the temperature of the soft water after heating can reach 95℃.

[0008] Furthermore, in the second measure, the spray cooling tower adopts a packed structure, with regenerated gas entering from the bottom of the tower and cooling water sprayed from the top of the tower. The regenerated gas is cooled to about 40°C, while water vapor is condensed and recovered.

[0009] Furthermore, in the third measure, the sprayed water is water or amine liquid, and the plate heat exchanger is set in parallel with the original sprayed cooling circuit to achieve precise control of the sprayed water temperature.

[0010] Furthermore, in the fourth measure, the control system upgrade includes adding an expert optimization module to the DCS system to collaboratively optimize the amine liquid circulation volume, regeneration tower temperature and pressure, and adding a vibration monitoring system for key equipment.

[0011] Furthermore, in Measure 5, the cost accounting cycle is weekly or ten-day period, and the set cost deficit warning threshold is 150 yuan / ton.

[0012] Compared with the prior art, the advantages of this invention are: 1. Significant cost reduction: Through the combined implementation of multiple measures, it is estimated that the cost of molten iron can be reduced by 40-50 yuan / ton, significantly narrowing the cost gap between the HyCROF process and the traditional process, and enhancing its economic competitiveness.

[0013] 2. Comprehensive improvement in energy efficiency: This includes the integrated utilization and conservation of thermal, electrical, and chemical energy, achieving system-level energy efficiency improvement.

[0014] 3. Resource recycling: Waste heat from the sintering process is used in the decarbonization system to achieve cross-process energy cascade utilization, which is in line with the concept of circular economy.

[0015] 4. Reliable system operation: Through equipment improvement and intelligent control, the lifespan of key equipment and the operational stability of the entire system are enhanced, reducing unplanned downtime.

[0016] 5. Clear implementation path: All measures are based on existing mature technologies, the difficulty and risk of modification are controllable, and they are easy to implement and promote on existing HyCROF devices. Attached Figure Description

[0017] Figure 1 This is a diagram showing the overall measures related to the energy efficiency improvement and cost control method of the HyCROF system of the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below through specific embodiments: like Figure 1 As shown: A method for improving energy efficiency and controlling cost in a hydrogen-rich carbon-circulating oxygen blast furnace system, comprising the following synergistic technical measures: Measure 1: Low-grade waste heat is used for amine regeneration: Low-temperature waste gas (85-120℃) generated by the sintering ring cooler in the steel plant is collected. The heat recovery system, consisting of a waste gas collection hood, a circulating fan, a soft water circulation loop, and a plate heat exchanger, heats the soft water to above 90℃. This soft water is then used as a heat medium in the reboiler of the amine regeneration tower in the decarbonization system, replacing the original 0.5-0.8MPa saturated steam used to heat the lean amine liquid to desorb CO2. The low-temperature waste gas originates from the third and fourth sections of the sintering ring cooler, with a temperature range of 90-110℃. The heat recovery system is a closed-loop soft water circulation system, and the temperature of the heated soft water can reach 95℃.

[0019] Measure 2: Upgrade of the high-efficiency desorption regenerated gas spray cooling system: Replace the traditional shell-and-tube regenerated gas cooler with a direct contact spray cooling tower. The high-temperature regenerated gas and the spray cooling water directly contact each other for heat and mass transfer, reducing the total pressure difference of the regenerated gas system from 30 kPa to below 5 kPa. The spray cooling tower adopts a packed structure, with regenerated gas entering from the bottom of the tower and cooling water spraying from the top of the tower. The regenerated gas is cooled to about 40°C, while water vapor is condensed and recovered at the same time.

[0020] Measure 3: Improve the efficiency of decarbonized compressors: Add a plate heat exchanger in parallel to the liquid injection cooling circuit of the screw compressor, and use the factory circulating cooling water at 28-32℃ to reduce the temperature of the liquid injection water from 45℃ to about 33℃, thereby improving the isothermal efficiency of the compressor; the liquid injection water is water or amine liquid, and the plate heat exchanger is set in parallel with the original liquid injection cooling circuit to achieve precise control of the liquid injection water temperature.

[0021] Measure 4: Optimization and Intelligent Control of Amine Solution System: Control the amine solution concentration at 28%-32%, stabilize the pH value at 10.5-11.5, and scientifically add corrosion inhibitors and defoamers; upgrade the control system, add online monitoring equipment and big data fault early warning model to achieve preventive maintenance; the control system upgrade includes adding an expert optimization module to the DCS system to coordinate the optimization of amine solution circulation, regeneration tower temperature and pressure, and adding a vibration monitoring system for key equipment.

[0022] Measure 5: Iron cost accounting and early warning mechanism: Regularly calculate the iron cost of HyCROF mode and traditional mode. When the cost deficit exceeds the set threshold, an early warning will be triggered, and optimization measures will be initiated to form a closed-loop management. The cost accounting cycle is weekly or every ten days, and the set early warning threshold for cost deficit is 150 yuan / ton.

[0023] The specific implementation process of the above method in a 2500m³ HyCROF system at a steel plant is as follows. The implementation of this invention is a systems engineering project; the various measures are interconnected and work synergistically to improve energy efficiency and reduce costs.

[0024] Measure 1: Use low-grade waste heat for amine liquid regeneration: Heat source selection: Utilize the exhaust gas generated in the third and fourth sections of the annular cooler of the 265㎡ sintering machine, with a temperature range of 90-110℃ and a total heat source power of approximately 57MW / h; System composition: A new exhaust gas collection hood and circulating fan are built to introduce exhaust gas at about 100°C into a large air-to-water plate heat exchanger; at the same time, a closed soft water circulation system is established, in which the soft water is heated to about 95°C in the plate heat exchanger. Heat utilization: The heated soft water is transported through pipelines to the decarbonization area and enters the reboiler of the amine regeneration tower, which has been modified to be suitable for hot water heating, as a heat source for the regeneration of lean amine liquid. The original 0.5MPa steam boiler is significantly reduced in load or used as a backup. Benefit assessment: It is expected to completely replace the steam used for recycling, and the annual savings in steam consumption will translate to a reduction in the cost of molten iron of approximately 18 yuan per ton.

[0025] Measure 2: Upgrade the high-efficiency desorption regeneration gas spray cooling system: Equipment replacement: Remove the original shell-and-tube regenerated gas cooler and install a packed direct contact spray cooling tower; Process flow: Regenerated gas at about 110°C enters from the bottom of the tower and flows upward. Cooling water is sprayed evenly from the top of the tower by the spray system. It comes into full contact with the regenerated gas in the packing layer and is cooled to about 40°C. At the same time, some water vapor is condensed. The cooled regenerated gas is sent from the top of the tower to the subsequent process section. The cooling water that has absorbed heat is discharged from the bottom of the tower and is recycled after being cooled by the cooling tower. Implementation results: The system pressure difference was reduced from about 30 kPa to 5 kPa before the modification, the operating pressure of the regeneration tower was reduced by about 0.025 MPa, the consumption of regeneration steam was reduced by 12%, and the annual savings in electricity consumption and steam generation were equivalent to a reduction in the cost of molten iron of about 8 yuan / ton.

[0026] Measure 3: Improve the efficiency of the decarbonization compressor: Modification content: Connect a plate heat exchanger in parallel to each of the four screw compressors' liquid injection cooling circuits. After the liquid injection water comes out of the gas-liquid separator at the compressor outlet, part of it circulates along the original path, and the other part is introduced into the newly added plate heat exchanger to exchange heat with the 32℃ factory circulating cooling water. The temperature drops from 45℃ to 33℃, and the cooled liquid injection water returns to the compressor's liquid injection inlet. Implementation results: After the temperature of the sprayed water was reduced, the isothermal efficiency of the compressor increased by about 7%. While maintaining the same decarburization gas output (~185,000 Nm³ / h), the total power of the four compressors decreased by about 7%, and the annual power saving benefit was equivalent to a reduction of about 6 yuan / ton in the cost of molten iron.

[0027] Measure 4: Optimization and Intelligent Control of Amine Liquid System: Chemical management: The concentration of amine solution was strictly controlled from the original wide range of 25-35% to 30%±2%. An online pH meter was installed to automatically control the pH of the amine solution at around 11.0. A regular analysis system for amine solution was established, and corrosion inhibitors and defoamers were added scientifically based on the analysis results. Control system upgrade: An expert optimization module was added to the DCS system to collaboratively optimize key parameters such as amine circulation volume, regeneration tower temperature, and pressure. A vibration monitoring system was added to monitor the status of key equipment such as compressors and solution pumps to achieve predictive maintenance. Implementation results: By reducing downtime due to breakdowns and optimizing operations, costs can be indirectly reduced by approximately 5 yuan per ton of iron.

[0028] Measure 5: Cost Accounting and Early Warning Establish a weekly cost accounting system; the cost accounting template is shown in Table 1. Table 1 is a template for the weekly cost accounting system. When the trade deficit (XY) exceeds 150 yuan / ton for two consecutive weeks, the system will issue an automatic warning, and the cost reduction task force will analyze the reasons and take targeted optimization measures. Through the implementation of the above comprehensive measures, the cost deficit of molten iron in this 2500m³ HyCROF system can be narrowed from the current 157.6 yuan / ton to less than 100 yuan / ton, laying a solid foundation for the ultimate realization of economically feasible low-carbon ironmaking.

[0029] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for improving energy efficiency and controlling cost in a hydrogen-rich carbon-circulating oxygen blast furnace system, characterized in that, The following collaborative technical measures are included: Measure 1: Low-grade waste heat is used for amine regeneration: Low-temperature waste gas of 85-120℃ generated by the sintering ring cooler of the steel plant is collected and heated to above 90℃ through a heat recovery system consisting of a waste gas collection hood, a circulating fan, a soft water circulation loop and a plate heat exchanger. This soft water is then used as a heat medium to enter the reboiler of the amine regeneration tower in the decarbonization system, replacing the original 0.5-0.8MPa saturated steam heating of lean amine liquid to desorb CO2. Measure 2: Upgrade of the high-efficiency desorption regenerated gas spray cooling system: Replace the traditional shell-and-tube regenerated gas cooler with a direct contact spray cooling tower. The high-temperature regenerated gas and the spray cooling water directly contact each other for heat and mass transfer, reducing the total pressure difference of the regenerated gas system from 30 kPa to below 5 kPa. Measure 3: Improve the efficiency of decarbonized compressors: Add a plate heat exchanger in parallel to the liquid injection cooling circuit of the screw compressor, and use the 28-32℃ factory circulating cooling water to reduce the temperature of the liquid injection water from 45℃ to about 33℃, thereby improving the isothermal efficiency of the compressor. Measure 4: Optimization and intelligent control of the amine solution system: Control the amine solution concentration at 28%-32%, stabilize the pH value at 10.5-11.5, and scientifically add corrosion inhibitors and defoamers; upgrade the control system, add online monitoring equipment and big data fault early warning models to achieve preventive maintenance; Measure 5: Iron cost accounting and early warning mechanism: Regularly calculate the iron cost of HyCROF mode and traditional mode. When the cost deficit exceeds the set threshold, an early warning is triggered, and optimization measures are initiated to form a closed-loop management.

2. The method for improving energy efficiency and controlling cost of a hydrogen-rich carbon-circulating oxygen blast furnace system according to claim 1, characterized in that, In the first measure, the low-temperature exhaust gas comes from the third and fourth sections of the sintering ring cooler, with a temperature range of 90-110℃. The heat recovery system is a closed-loop soft water circulation system, and the temperature of the soft water after heating can reach 95℃.

3. The method for improving energy efficiency and controlling cost of a hydrogen-rich carbon-circulating oxygen blast furnace system according to claim 1, characterized in that, In the second measure, the spray cooling tower adopts a packed structure, with regenerated gas entering from the bottom of the tower and cooling water sprayed from the top of the tower. The regenerated gas is cooled to about 40°C, while water vapor is condensed and recovered.

4. The method for improving energy efficiency and controlling cost of a hydrogen-rich carbon-circulating oxygen blast furnace system according to claim 1, characterized in that, In the third measure, the sprayed water is water or amine liquid, and the plate heat exchanger is set in parallel with the original sprayed cooling circuit to achieve precise control of the sprayed water temperature.

5. The method for improving energy efficiency and controlling cost of a hydrogen-rich carbon-circulating oxygen blast furnace system according to claim 1, characterized in that, The fourth measure includes upgrading the control system by adding an expert optimization module to the DCS system to coordinate the optimization of amine liquid circulation, regeneration tower temperature and pressure, and adding a vibration monitoring system for key equipment.

6. The method for improving energy efficiency and controlling cost of a hydrogen-rich carbon-circulating oxygen blast furnace system according to claim 1, characterized in that, In Measure 5, the cost accounting cycle is weekly or every ten days, and the set cost deficit warning threshold is 150 yuan / ton.

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