Low emission and carbon capture coupling process for steel production

Abstract

The invention provides a low emission and carbon capture coupling process for steel production, and relates to the technical field of steel generation. The method comprises the following steps: pretreating blast furnace gas, then carrying out carbon capture to obtain carbon dioxide, carrying out desulfurization treatment on sintering flue gas to obtain desulfurized fly ash, treating the carbon dioxide and the desulfurized fly ash to generate stable carbonate, and mineralizing and sealing the carbon dioxide. Carbon dioxide obtained by carbon capture of blast furnace gas reacts with solid waste generated by sintering flue gas desulfurization, so that carbon dioxide mineralization is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel production, and particularly relates to a steel production low-emission and carbon capture coupling process. BACKGROUND

[0002] The steel industry is an industrial industry mainly engaged in industrial production activities such as black metal mineral mining and selection and black metal smelting and processing, including mineral mining and selection of metals such as iron, chromium and manganese, iron smelting industry, steel industry, steel processing industry, ferroalloy smelting industry, steel wire and product industry and other sub-industries, and is one of the important raw material industries in the country.

[0003] At present, in the steel production, greenhouse gases including carbon dioxide are emitted, and the emission of greenhouse gases has a negative impact on the environment, and how to reduce emissions and achieve carbon capture is a problem to be solved. SUMMARY

[0004] The purpose of the present application is to develop a steel production low-emission and carbon capture coupling process in which carbon dioxide obtained by carbon capture of blast furnace gas is reacted with solid waste produced by sintering flue gas desulfurization to achieve carbon dioxide mineralization.

[0005] The present application is realized by the following technical scheme:

[0006] A steel production low-emission and carbon capture coupling process, comprising: pretreating blast furnace gas, then performing carbon capture to obtain carbon dioxide, desulfurizing sintering flue gas to obtain desulfurization ash, and treating carbon dioxide and desulfurization ash to generate stable carbonate to mineralize and store carbon dioxide.

[0007] Optionally, the blast furnace gas pretreatment includes dust removal of the blast furnace gas, followed by removal of organic sulfur and hydrogen sulfide.

[0008] Optionally, the dust removal of the blast furnace gas can be bag dust removal, removal of organic sulfur by a low-temperature hydrolysis tower, and removal of hydrogen sulfide by an activated coke adsorption tower.

[0009] Optionally, the carbon capture includes passing the pretreated gas into a multi-bed VPSA system, using a hydrophobic MOFs adsorbent to adsorb carbon dioxide, capturing the carbon dioxide by the adsorbent, discharging tail gas, and subsequently recovering the carbon dioxide by vacuum desorption.

[0010] Optionally, nitrogen is separated from the tail gas by PSA, and carbon monoxide and hydrogen are reused as fuel.

[0011] Optionally, the desulfurization treatment of the sintering flue gas comprises passing the sintering flue gas into a circulating fluidized bed desulfurization tower, spraying a high-activity calcium-based absorbent, achieving desulfurization and obtaining by-product high-calcium desulfurization ash, the main components of the desulfurization ash including unreacted calcium hydroxide, calcium sulfate and calcium sulfite, and the tail gas output after desulfurization being discharged after low-temperature SCR denitration and dust removal.

[0012] Optionally, the high-activity calcium-based absorbent is nano calcium hydroxide slurry.

[0013] Optionally, the carbon dioxide mineralization comprises:

[0014] The desulfurization ash is dried by a fluidized bed dryer;

[0015] Then, the desulfurization ash is ground by a ball mill;

[0016] Finally, the desulfurization ash is sent into a three-stage slurry reaction system;

[0017] The three-stage slurry reaction system comprises a first-stage reaction kettle, a second-stage reaction kettle and a third-stage aging tank, the desulfurization ash is reacted with carbon dioxide in the first-stage reaction kettle, then neutralized in the second-stage reaction kettle, and finally aged in the third-stage aging tank to promote the crystal type conversion of calcium carbonate and generate stable calcite.

[0018] Optionally, water is passed into the first-stage reaction kettle to mix with the desulfurization ash to form slurry, oxygen and carbon dioxide obtained by carbon capture are passed in, and an ionic liquid catalyst is added.

[0019] Steel slag is added into the second-stage reaction kettle, and the steel slag is ground by a ball mill in advance.

[0020] Optionally, the materials in the third-stage aging tank are sequentially sent to a centrifuge for separation and a drying machine for drying, and the components of the obtained solid product include calcium carbonate, calcium sulfate and inert components.

[0021] The beneficial effects of the present application are:

[0022] The present application processes blast furnace gas and sintering flue gas, processes the obtained carbon dioxide and desulfurization ash to achieve carbon dioxide mineralization, in the process, the generated hydrogen-rich gas is reused to reduce fossil fuel consumption, and the steel slag and desulfurization ash are also accommodated, thereby simultaneously achieving low emission, carbon capture, desulfurization and denitration, solid waste resourceization and system energy consumption reduction in one process. DETAILED DESCRIPTION

[0023] In the following, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the following description is considered to be exemplary in nature rather than limiting.

[0024] The embodiments of the present application are described in detail below.

[0025] The present application discloses a low-emission and carbon capture coupling process for steel production, which comprises the following steps: pretreating blast furnace gas, then performing carbon capture to obtain carbon dioxide, performing desulfurization treatment on sintering flue gas to obtain desulfurization ash, and treating the carbon dioxide and the desulfurization ash to generate stable carbonate to mineralize and store the carbon dioxide.

[0026] The pretreatment of the blast furnace gas comprises the following steps:

[0027] The blast furnace gas is subjected to dust removal, then organic sulfur and hydrogen sulfide are removed, the dust removal of the blast furnace gas can be bag dust removal, the removal of organic sulfur can be performed through a low-temperature hydrolysis tower, and the removal of hydrogen sulfide can be performed through an activated coke adsorption tower;

[0028] The carbon capture comprises the following steps:

[0029] The pretreated gas is introduced into a multi-bed VPSA (vacuum pressure swing adsorption) system, and carbon dioxide is adsorbed by using a hydrophobic MOF (metal organic framework) adsorbent, the carbon dioxide is captured by the adsorbent, and subsequent vacuum desorption is performed to recover the carbon dioxide, and the main components of the exhaust gas discharged are carbon monoxide, hydrogen and nitrogen;

[0030] For the exhaust gas, PSA (pressure swing adsorption) can be performed to separate nitrogen, and carbon monoxide and hydrogen are reused as fuel.

[0031] The desulfurization treatment of the sintering flue gas comprises the following steps:

[0032] The sintering flue gas is introduced into a circulating fluidized bed desulfurization tower, and a high-activity calcium-based absorbent is sprayed, the high-activity calcium-based absorbent is nano calcium hydroxide slurry, desulfurization is realized, and by-product high-calcium desulfurization ash is obtained, the main components of the desulfurization ash include unreacted calcium hydroxide, calcium sulfate and calcium sulfite, and the tail gas output after desulfurization is discharged after low-temperature SCR denitration and dust removal.

[0033] The carbon dioxide mineralization comprises the following steps:

[0034] The desulfurization ash is dried by a fluidized bed dryer, then ground to a particle size of ≤50 μm by a ball mill to improve the reaction activity, then the desulfurization ash is sent into a three-stage slurry reaction system, the three-stage slurry reaction system comprises a first-stage reaction kettle, a second-stage reaction kettle and a third-stage aging tank.

[0035] In the primary reactor, water is mixed with desulfurization ash to form a slurry, oxygen and carbon dioxide recovered in carbon capture are introduced, and an ionic liquid catalyst is added. The ionic liquid catalyst can be 1-butyl-3-methylimidazolium bromide. The temperature in the primary reactor is 60-80°C, and the pressure in the primary reactor is 0.5-1 MPa. In the primary reactor, the oxygen reacts with calcium sulfite in the desulfurization ash to form calcium sulfate, and the calcium hydroxide and calcium sulfate react with carbon dioxide to form calcium carbonate and sulfuric acid that needs to be neutralized.

[0036] The material is introduced from the primary reactor into the secondary reactor. The secondary reactor is provided with steel slag, which is ground in advance by a ball mill. The steel slag contains 40-60% calcium oxide, which reacts with sulfuric acid to form calcium sulfate.

[0037] The material is sent from the secondary reactor to a tertiary aging tank, where it stays for several hours to promote the transformation of calcium carbonate crystal form and generate stable calcite. Then the material is sequentially sent to a centrifuge for separation and a drying machine for drying to obtain a solid product. The solid product contains calcium carbonate, calcium sulfate, and inert components. If the heavy metal content of the solid product meets the standard, it can be used as a soil conditioner for PH adjustment.

[0038] The above embodiments are only preferred embodiments of the present application and are not intended to limit the technical solutions of the present application. Any technical solutions that can be realized on the basis of the above embodiments without creative labor should be considered to fall within the scope of protection of the present patent.

Claims

1. A coupled process for low-emission and carbon capture in steel production, characterized in that, include: The blast furnace gas is pretreated and then carbon capture is performed to obtain carbon dioxide. The sintering flue gas is desulfurized to obtain desulfurized ash. The carbon dioxide and desulfurized ash are then treated to generate stable carbonates, thereby mineralizing and storing the carbon dioxide.

2. The low-emission and carbon capture coupling process for steel production according to claim 1, characterized in that, Blast furnace gas pretreatment includes dust removal from the blast furnace gas, followed by removal of organic sulfur and hydrogen sulfide.

3. The low-emission and carbon capture coupling process for steel production according to claim 2, characterized in that, Dust removal of blast furnace gas can be achieved using bag filters, organic sulfur removal via a low-temperature hydrolysis tower, and hydrogen sulfide removal via an activated coke adsorption tower.

4. The low-emission and carbon capture coupling process for steel production according to claim 1, characterized in that, Carbon capture involves feeding pretreated coal gas into a multi-bed VPSA system, using hydrophobic MOFs adsorbents to adsorb carbon dioxide. The carbon dioxide is captured by the adsorbents, the exhaust gas is discharged, and subsequent vacuum desorption is performed to recover the carbon dioxide.

5. The low-emission and carbon capture coupling process for steel production according to claim 4, characterized in that, The exhaust gas is subjected to PSA to separate nitrogen and reuse carbon monoxide and hydrogen as fuel.

6. The low-emission and carbon capture coupling process for steel production according to claim 1, characterized in that, The desulfurization treatment of sintering flue gas includes passing the sintering flue gas into a circulating fluidized bed desulfurization tower, injecting a highly active calcium-based absorbent to achieve desulfurization and obtain by-product high-calcium desulfurization ash. The main components of the desulfurization ash include unreacted calcium hydroxide, calcium sulfate, and calcium sulfite. The tail gas output after desulfurization is discharged after low-temperature SCR denitrification and dust removal.

7. The low-emission and carbon capture coupling process for steel production according to claim 6, characterized in that, The highly active calcium-based absorbent is a nano-calcium hydroxide slurry.

8. The low-emission and carbon capture coupling process for steel production according to any one of claims 1 to 7, characterized in that, Carbon dioxide mineralization includes: The desulfurization ash is dried using a fluidized bed dryer; Then it is ground using a ball mill; Finally, the desulfurization ash is sent into the three-stage slurry reaction system; The three-stage slurry reaction system includes a primary reactor, a secondary reactor, and a tertiary aging tank. The desulfurization ash reacts with carbon dioxide in the primary reactor, then is neutralized in the secondary reactor, and finally aged in the tertiary aging tank to promote the transformation of calcium carbonate crystal form and generate stable calcite.

9. The low-emission and carbon capture coupling process for steel production according to claim 8, characterized in that, Water and desulfurization ash are mixed to form a slurry in the primary reactor, oxygen and carbon dioxide obtained from carbon capture are introduced, and an ionic liquid catalyst is added. Steel slag is added to the secondary reactor, and the steel slag is ground in advance using a ball mill.

10. The low-emission and carbon capture coupling process for steel production according to claim 8, characterized in that, The material in the three-stage aging tank is sequentially sent to a centrifuge for separation and a dryer for drying. The resulting solid product consists of calcium carbonate, calcium sulfate, and inert components.