A system and method for preparing low-ash low-porosity coke for hydrogen-rich blast furnace

Abstract

A low-ash low-porosity coke preparation system and method for hydrogen-rich blast furnaces, the system comprising a coal blending unit, a crushing unit, a multifunctional pickling integrated unit, a dehydration unit, a pulverizing unit, a jacking unit, a coking unit, a coke quenching unit, and a screening unit.

Description

Technical Field

[0001] This invention relates to coke for blast furnace smelting, and more particularly to a system and method for preparing low-ash, low-porosity coke for hydrogen-rich blast furnaces. Background Technology

[0002] Traditional blast furnace ironmaking relies on coke combustion to provide the heat needed for the reduction reaction and produce carbon monoxide (CO), a reducing agent. Under the influence of the reducing gas, iron ore is reduced while simultaneously generating a large amount of carbon dioxide (CO2). To achieve emission reduction goals in blast furnaces, metallurgists have proposed a hydrogen-rich blast furnace operation process. This process uses hydrogen-rich gas as the ideal reducing agent to replace part of the coke, while the reduction product is water, thus achieving the goal of emission reduction in blast furnaces.

[0003] Current research on hydrogen-enriched blast furnace operation shows that the addition of hydrogen can promote the downward movement and thinning of the softening zone, significantly improving the reducibility of iron ore. This indicates that hydrogen is more efficient than coke in reducing iron oxides. However, with the increase of hydrogen-enriched gas in the furnace, the increased water content in the atmosphere promotes the gasification reaction of coke. While consuming carbon, this also damages the coke structure. During the descent within the furnace, the coke particle size decreases, generating a large amount of coke dust, which is detrimental to the permeability of the blast furnace and affects the efficiency of hydrogen utilization.

[0004] The ash content and porosity of coke typically have a significant impact on its reactivity. Coke with high ash content and high porosity exhibits high reactivity, leading to a substantial decrease in strength after reaction. Therefore, hydrogen-rich blast furnace operation must place greater emphasis on low ash content and low porosity of coke to ensure its skeletal role within the furnace, thereby maximizing hydrogen utilization and achieving the ultimate emission reduction in the blast furnace ironmaking process. Summary of the Invention

[0005] Therefore, the purpose of this invention is to address the problems existing in the prior art by proposing a system and method for preparing low-reactivity, high-strength coke for hydrogen-rich blast furnaces. By integrating the acid washing-water washing-flue gas waste heat utilization-tamping coking process, the goal of improving coal deashing efficiency and low-porosity coke production efficiency is achieved.

[0006] To achieve the above objectives, the present invention proposes a system comprising a coal blending unit, a crushing unit, a multi-functional integrated acid washing unit, a dewatering unit, a pulverizing unit, a compaction unit, a coking unit, a coke quenching unit, and a screening unit.

[0007] Furthermore, the coal blending unit is blended with 10-30% weakly caking coal.

[0008] Furthermore, the crushing unit uses a crusher to crush the coal to obtain coal blocks with a particle size range of 4mm-7mm.

[0009] Furthermore, the multifunctional pickling unit includes a pickling tank, with a coal inlet, a liquid inlet, and an exhaust outlet at the top. Two nozzles are installed inside the pickling tank, positioned on either side of the tank's symmetrical line. These nozzles utilize the high-temperature nitrogen generated during coke quenching to heat and stir the coal and washing liquid within the tank. Inside the pickling tank, a rubber conical float is installed below the nozzles. The diameter of the rubber conical float is slightly smaller than the tank's diameter. When no washing liquid is injected into the tank, the rubber conical float rests on the bottom support of the tank. When washing liquid is injected, the rubber conical float floats... The coal blocks, which float in the pickling tank and are simultaneously added through the coal inlet, also fall onto the cone cap of the rubber cone cap floating plate. After pickling or water washing is completed, when the annular outlet around the bottom support of the pickling tank is opened, the washing liquid in the pickling tank, carrying the washed ash, first passes through the gap between the rubber cone cap floating plate and the tank body of the pickling tank, and is discharged through the annular outlet. As the washing liquid is discharged, the rubber cone cap floating plate also descends until it sits back on the bottom support of the pickling tank. At this time, the descending channel between the coal blocks on its cone cap and the annular outlet is also opened, so that the washed coal blocks can be discharged through the annular outlet.

[0010] Furthermore, multiple turbine grooves are provided on the cone of the rubber cone-shaped floating disc.

[0011] Furthermore, the blow pipe is located on both sides of the symmetry line of the pickling tank, with an angle of 60°-75° to the pickling tank wall and an angle of 30°-40° deflection from the symmetry line of the pickling tank.

[0012] Furthermore, the dehydration unit is a drying chamber that uses high-temperature nitrogen gas generated during coke quenching to heat the acid-washed coal blocks to obtain deashed coal blocks; the crushing unit can use a crusher to crush the deashed coal blocks to obtain deashed coal powder with a particle size range of 0.5mm-1mm; the compaction unit uses a compactor to compact the deashed coal powder into deashed coal cakes, increasing the bulk density of the coal; the coking unit can heat the deashed coal cakes in the absence of air to produce coke; the crushing and screening unit uses a screening machine to screen the coke, with coke with a particle size <15mm returned to the crushing unit and coke with a particle size >15mm used in the blast furnace; the crushing and screening unit uses a screening machine to screen the coke, with coke with a particle size <15mm returned to the crushing unit and coke with a particle size >15mm used in the blast furnace.

[0013] This invention also provides a method for preparing low-ash, low-porosity coke for hydrogen-rich blast furnaces, comprising the following steps:

[0014] S1. After the coal is blended, it is put into the crusher and crushed to obtain coal blocks with a particle size of 4mm-7mm.

[0015] S2. Place coal lumps with a particle size of 4mm-7mm into the pickling tank. The pickling tank is equipped with a coal feeding port, a liquid feeding port, and an exhaust port at the top. Two nozzles are installed inside the pickling tank, located on either side of the tank's symmetrical line. These nozzles utilize the high-temperature nitrogen generated during coke quenching to heat and stir the coal lumps and washing liquid within the tank. Inside the pickling tank, below the nozzles, is a rubber conical float. The diameter of the rubber conical float is slightly smaller than the tank's diameter. When no washing liquid is injected into the tank, the rubber conical float rests on the bottom support of the pickling tank. Add a 3%-5% hydrochloric acid solution at a solid-liquid ratio of 1:10. The rubber conical float floats in the pickling tank, and simultaneously, through the addition of coal... The coal chunks added at the inlet also fall onto the cone cap of the rubber cone cap floating plate; the solution is heated and stirred using high-temperature nitrogen gas generated by coke quenching; when pickling or water washing is completed, when the annular outlet around the bottom support of the pickling tank is opened, the washing liquid in the pickling tank, carrying the washed ash, first passes through the gap between the rubber cone cap floating plate and the tank body of the pickling tank, and is discharged through the annular outlet; as the washing liquid is discharged, the rubber cone cap floating plate also descends until it sits on the bottom support of the pickling tank again, and at this time the descending channel between the coal chunks on its cone cap and the annular outlet is also opened, and high-temperature nitrogen gas is sprayed into the tank again through the nozzle, drying the coal chunks while also discharging them through the annular outlet;

[0016] S4. The deashed coal blocks are crushed to obtain deashed coal powder with a particle size range of 0.5mm-1mm.

[0017] S5. The deashed coal powder is formed into deashed coal cake in the tamping machine. The deashed coal cake and 5% asphalt are added to the coking chamber as a binder for coking.

[0018] S6. The red-temperature coke is cooled with nitrogen in the quenching tower. The resulting high-temperature nitrogen is used as the gas for blowing and stirring in step S2, and as the gas for high-temperature drying in step S3.

[0019] S7. The cooled coke is crushed using a crusher. Coke with a particle size <15mm is returned to the pulverizing unit, while coke with a particle size >15mm is used in the blast furnace.

[0020] This invention relates to a multifunctional integrated pickling and washing device that integrates pickling, water washing, and filtration processes. The angle between the spray pipe and the pickling tank wall is 60°-75°, and the deflection angle from the pickling tank's line of symmetry is 30°-40°, resulting in excellent spraying effect and strong stirring capacity, thus improving deashing and cleaning efficiency. Simultaneously, the gas sprayed through the spray pipe is high-temperature flue gas generated during coke quenching, reducing energy consumption during production. The coal cake produced by the tamping machine increases the bulk density of the coal powder. Furthermore, the addition of asphalt as a binder during the coking process enhances the coal's bonding properties, significantly reducing the porosity of the finished coke. This enables the preparation of low-ash, low-porosity coke suitable for use in hydrogen-rich blast furnaces. Attached Figure Description

[0021] Figure 1 This is a flowchart of a preferred embodiment of the hydrogen-rich blast furnace coke preparation system with low ash content and low porosity.

[0022] Figure 2 This is a schematic diagram of the multifunctional integrated pickling device after adding liquid in a preferred embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the multifunctional integrated pickling device after liquid discharge in a preferred embodiment of the present invention;

[0024] Figure 4 yes Figure 2 Cross-sectional view of the intermediate pickling tank. Detailed Implementation

[0025] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0026] The low-reactivity, high-strength coke preparation system for hydrogen-rich blast furnaces according to the present invention includes a coal blending unit, a crushing unit, an integrated acid washing unit, a dewatering unit, a pulverizing unit, a compaction unit, a coking unit, a quenching unit, and a crushing and screening unit. The coal blending unit is connected to the crushing unit for blending coal before it enters the crusher to crush the coal blocks. The crushing unit is connected to the integrated acid washing unit for acid washing and water washing to remove ash from the crushed coal blocks. The deashed coal blocks enter the dewatering unit for drying. The dewatering unit is connected to the pulverizing unit for pulverizing the deashed coal blocks into deashed coal powder. The pulverizing unit is connected to the compaction unit for mechanical compaction of the coal powder from the pulverizing unit to obtain high-density deashed coal cakes. The compaction unit is connected to the coking unit for refining the deashed coal cakes into coke. The coking unit is connected to the quenching unit to lower the temperature of the red-temperature coke. High-temperature gases are collected for use in the integrated pickling and dehydration units. The quenching unit is connected to the crushing and screening unit for coke crushing to obtain coke with a particle size suitable for blast furnace smelting.

[0027] like Figure 2 , 3As shown, in a further embodiment, the integrated pickling unit includes a pickling tank 1. The upper part of the pickling tank 1 is provided with a coal inlet 2 and a liquid inlet and exhaust outlet 3. Two nozzles 4 are installed inside the pickling tank 1. The nozzles 4 are located on both sides of the symmetry line of the pickling tank, and are used to heat and stir the coal and washing liquid inside the pickling tank 1 using high-temperature nitrogen gas generated during coke quenching. The angle between the nozzles 4 and the wall of the pickling tank 1 is 60°-75°, and the deflection angle from the symmetry line of the pickling tank 1 is 30°-40°. Inside the pickling tank 1, a rubber conical cap float 5 is installed below the nozzles 4. The diameter of the rubber conical cap float 5 is slightly smaller than the diameter of the pickling tank 1, and its conical cap is provided with multiple turbine grooves 10. When no washing liquid is injected into the tank, the rubber conical float 5 rests on the bottom support 6 of the pickling tank 1. After the washing liquid is injected into the tank, the rubber conical float 5 floats on the pickling tank 1. At the same time, the coal blocks added through the coal inlet 2 also fall on the conical cap of the rubber conical float 5 and sink under the influence of gravity, suspending in the washing liquid. At this time, the high-temperature nitrogen gas injected from the nozzle 4 agitates the washing liquid, and at the same time, the turbine groove 10 drives the rubber conical float 5 to rotate, thereby further promoting the agitation of the washing liquid in the pickling tank 1. After pickling or water washing is completed, when the annular outlet 8 around the bottom support 6 of the pickling tank 1 is opened, the washing liquid in the pickling tank 1, carrying the washed ash, first passes through the gap 7 between the rubber conical float 5 and the tank body of the pickling tank 1, and is discharged through the annular outlet 8. As the washing liquid is discharged, the rubber cone-shaped floating plate 5 descends until it rests again on the bottom support 6 of the pickling tank 1. At this time, the descending channel 9 between the coal block on its cone and the annular outlet 8 also opens, and high-temperature nitrogen gas is injected into the tank again through the nozzle 4. While drying the coal block, it is also discharged through the annular outlet 8. In this way, unlike existing coal pickling equipment, in the pickling tank 1 of this invention, the washing liquid containing ash is discharged first from below the coal block, and there is no ash retention between the coal blocks. This can minimize the residual ash in the washed coal blocks. At the same time, while drying and discharging the washed coal blocks, the high-temperature nitrogen gas can also further blow away the residual ash between the coal blocks, laying a good foundation for reducing the ash content of the subsequent coke.

[0028] This embodiment determines the use of four types of coking coal, namely fat coal, gas coal, coking coal and lignite, and specifically determines the proportions shown in Table 1.

[0029]

[0030] Then see Figure 1 The process flow for preparing low-ash, low-porosity coke involves the following steps:

[0031] S1. After the coal is blended, it is put into the crusher and crushed to obtain coal blocks with a particle size of 4mm-7mm.

[0032] S2. Place coal lumps with a particle size of 4mm-7mm into the pickling tank, and add a 3%-5% hydrochloric acid solution at a solid-liquid ratio of 1:10 until the tank is 1 / 3 full. Insert the nozzle from the spray gun outlet of the pickling tank below the solution surface, and use the high-temperature nitrogen gas generated by coke quenching to heat and stir the solution. After filtering the waste liquid through the filter port, add water, and spray and stir again to clean the coal lumps. Filter after cleaning is complete.

[0033] S3. The cleaned and filtered coal blocks are sent into the drying chamber and dehydrated using high-temperature nitrogen gas to obtain deashed coal blocks.

[0034] S4. The deashed coal blocks are crushed to obtain deashed coal powder with a particle size range of 0.5mm-1mm.

[0035] S5. The deashed coal powder is formed into deashed coal cake in the tamping machine. The deashed coal cake and 5% asphalt are added to the coking chamber as a binder for coking.

[0036] S6. The red-temperature coke is cooled with nitrogen in the quenching tower. The resulting high-temperature nitrogen is used as the gas for blowing and stirring in step S2, and as the gas for high-temperature drying in step S3.

[0037] S7. The cooled coke is crushed using a crusher. Coke with a particle size <15mm is returned to the pulverizing unit, while coke with a particle size >15mm is used in the blast furnace.

[0038] As shown in Table 1, the obtained coke has an ash content of 6%–8%, a sulfur content of 0.6%–0.8%, a total porosity of 30%–36%, a reactivity of 15%–19%, and a post-reaction strength of 78%–84%. Compared with ordinary coke, it achieves a significant reduction in ash content and porosity, a decrease in reactivity, and a significant increase in post-reaction strength, realizing the preparation of low-reactivity, high-strength coke for hydrogen-rich blast furnaces. Simultaneously, the multifunctional integrated pickling equipment provided by this invention integrates the pickling-water washing-filtration process. The angle between the injection pipe and the pickling tank wall is 60°–75°, and the deflection angle with the symmetry line of the pickling tank is 30°–40°, resulting in good injection effect and strong stirring ability, improving deashing and cleaning efficiency. Furthermore, the gas injected by the injection pipe is the high-temperature flue gas generated during coke quenching, utilizing the high-temperature flue gas for injection reduces production energy consumption. The coal briquettes produced using a tamping machine increase the bulk density of pulverized coal. Simultaneously, the addition of asphalt as a binder during the coking process enhances the coal's bonding properties and significantly reduces the porosity of the finished coke. This enables the preparation of low-ash, low-porosity coke for use in hydrogen-rich blast furnaces.

[0039] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A system for preparing low-ash, low-porosity coke for hydrogen-rich blast furnaces, characterized in that, The system includes a coal blending unit, a crushing unit, a multi-functional acid washing unit, a dewatering unit, a pulverizing unit, a compaction unit, a coking unit, a quenching unit, and a screening unit, connected in sequence. The coal blending unit blends the coal and transports the blended coal to the crushing unit. The crushing unit crushes the blended coal and transports the crushed coal blocks to the multi-functional acid washing unit. The multi-functional acid washing unit performs acid washing and water washing on the coal blocks and transports the washed coal blocks to the dewatering unit. The dewatering unit dehydrates and dries the washed coal blocks and transports the resulting deashed coal blocks to the pulverizing unit. The pulverizing unit crushes the deashed coal blocks... The coal block is crushed into deashed coal powder and the deashed coal powder is conveyed to the compaction unit. The compaction unit is used to compact the deashed coal powder into deashed coal cake and convey the deashed coal cake to the coking unit. The coking unit is used to refine the deashed coal cake into coke and convey the obtained coke to the quenching unit. The quenching unit is used to cool the coke with nitrogen and convey the cooled coke to the screening unit. The screening unit is used to screen the cooled coke. The quenching unit is also connected to the multifunctional acid washing unit and the dewatering unit respectively, so as to convey the high-temperature nitrogen generated during the quenching process to the multifunctional acid washing unit and the dewatering unit. The multifunctional pickling unit includes a pickling tank. The upper part of the pickling tank is provided with a coal feeding port and a liquid feeding and exhaust port. The pickling tank is provided with two nozzles, which are located on both sides of the symmetry line of the pickling tank. They are used to heat and stir the coal and washing liquid in the pickling tank using the high-temperature nitrogen gas generated by the coke quenching unit. The angle between the nozzle and the wall of the pickling tank is 60°-75°, and the deflection angle of the nozzle relative to the symmetry line of the pickling tank is 30°-40°. A rubber cone float is installed inside the pickling tank below the nozzle. The diameter of the rubber cone float is smaller than the diameter of the pickling tank. The cone of the rubber cone float has multiple turbine grooves. The bottom of the pickling tank is provided with a base support for supporting the rubber cone float. An annular outlet is provided around the base support. When no washing liquid is injected into the pickling tank, the rubber cone-shaped floating plate sits on the base. When washing liquid is injected into the pickling tank, the rubber cone-shaped floating plate floats in the washing liquid. Coal blocks added through the coal feeding port fall onto the cone of the rubber cone-shaped floating plate. High-temperature nitrogen gas sprayed from the nozzle heats and stirs the washing liquid, and drives the rubber cone-shaped floating plate to rotate through the turbine groove. When pickling or washing is completed and the annular outlet is opened, the washing liquid in the pickling tank, carrying the ash removed, passes through the gap between the rubber cone-shaped floating plate and the tank body of the pickling tank and is discharged through the annular outlet. As the washing liquid is discharged, the rubber cone-shaped floating plate descends and sits on the base, thereby opening the descending channel between the coal block located on the cone of the rubber cone-shaped floating plate and the annular outlet, so that the washed coal block is discharged through the descending channel through the annular outlet.

2. The coke preparation system as described in claim 1, characterized in that, The crushing unit uses a crusher to crush the coal to obtain coal blocks with a particle size of 4mm-7mm.

3. The coke preparation system as described in claim 1, characterized in that, The dehydration unit is a drying chamber used to heat the acid-washed coal blocks with high-temperature nitrogen gas generated by the quenching unit to obtain deashed coal blocks. The crushing unit uses a crusher to crush the deashed coal blocks to obtain deashed coal powder with a particle size of 0.5mm-1mm. The compaction unit uses a compactor to compact the deashed coal powder into deashed coal cakes to increase the bulk density of the coal. The coking unit is used to heat and refine the deashed coal cakes into coke under air-isolated conditions. The screening unit uses a screening machine to screen the coke and returns coke with a particle size of less than 15mm to the crushing unit, while sending coke with a particle size of more than 15mm into the blast furnace.

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