Rich steam direct reduction ironmaking device and carbon reduction method

Abstract

The invention provides a steam-rich direct reduction ironmaking device and a carbon reduction method.The method comprises the steps that a carbon-containing raw material and a steam-rich oxidizing agent are subjected to a reforming reaction to generate crude synthesis gas, the steam-rich oxidizing agent at least comprises water vapor and an oxidizing agent, and the oxidizing agent at least comprises one of air, oxygen and carbon dioxide; and mixing the crude synthesis gas with circulating coal gas to obtain reducing gas, carrying out direct reduction reaction, carrying out dust removal, dehumidification and decarburization treatment on the generated furnace top coal gas to obtain water, carbon dioxide and the circulating coal gas, discharging a part of water and carbon dioxide to the outside, and vaporizing the other part of water into water vapor after heat exchange treatment to generate the crude synthesis gas. According to the scheme, carbon emission can be effectively reduced, and process energy consumption is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy, and in particular relates to a steam-rich direct reduction ironmaking device and a carbon reduction method. Background Art

[0002] Currently, the synthesis gas produced by steam reforming carbon-containing feedstocks has a high hydrogen-to-carbon ratio. For example, the theoretical hydrogen-to-carbon ratio achieved from methane steam reforming is 3. Using this high-hydrogen-to-carbon ratio synthesis gas for shaft furnace ironmaking in the steel industry has significant potential for reducing carbon emissions. Furthermore, catalysts are commonly used during steam reforming to lower the reaction temperature, but their use requires a high water-to-carbon ratio in the feedstock, which increases process energy consumption. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a steam-rich direct reduction ironmaking device and a carbon reduction method to solve the above-mentioned problems.

[0004] To achieve the above-mentioned and other related purposes, the present invention provides a method for reducing carbon in ironmaking by direct reduction using rich steam, comprising:

[0005] reforming a carbonaceous feedstock and a steam-rich oxidant to generate a crude synthesis gas, wherein the steam-rich oxidant comprises at least water vapor and an oxidant, and the oxidant comprises at least one of air, oxygen, and carbon dioxide;

[0006] The crude synthesis gas is mixed with the circulating coal gas to form reducing gas, and a direct reduction reaction is carried out. The generated furnace top gas is subjected to dust removal, dehumidification and decarbonization treatment to obtain water, carbon dioxide and the circulating coal gas. Part of the water and carbon dioxide are discharged to the outside, and the other part of the water is vaporized into water vapor after heat exchange treatment to be used to generate crude synthesis gas.

[0007] Optionally, the carbonaceous feedstock and the steam-rich oxidant are subjected to a reforming reaction to generate a raw synthesis gas, comprising:

[0008] The water vapor in the steam-rich oxidant comes only from the water obtained by dust removal, dehumidification and decarbonization of the top gas;

[0009] or

[0010] Part of the water vapor in the steam-rich oxidant comes from external water supply, and part comes from water obtained by dust removal, dehumidification and decarbonization treatment of the top gas; the external water supply and the water obtained by dust removal, dehumidification and decarbonization treatment of the top gas are vaporized together after heat exchange treatment to obtain water vapor.

[0011] Optionally, the carbon-containing raw material is one or more of coal, biomass, liquid hydrocarbons, heavy oil, residual oil, natural gas, coalbed methane, shale gas, coke oven gas, coal-to-gas and chemical tail gas.

[0012] Optionally, the carbonaceous feedstock and the steam-rich oxidant are subjected to a reforming reaction comprising:

[0013] The reforming reaction is directly driven by high-temperature heat, and the reaction heat required for the reforming reaction comes from one or more of system self-heating, plasma heating, microwave heat, heat stored in a heat storage body, and industrial furnace heating, wherein the system self-heating at least includes the oxidation reaction heat of the carbon-containing raw material.

[0014] Optionally, part of the carbon dioxide obtained by removing dust, dehumidifying and decarbonizing the top gas is used as the oxidant.

[0015] Optionally, when water is processed by heat exchange to generate water vapor, the water cools the direct reduced iron produced by the direct reduction reaction, so that the water is vaporized into water vapor.

[0016] To achieve the above-mentioned and other related purposes, the present invention provides a steam-rich direct reduction ironmaking device, which is applied to the above-mentioned steam-rich direct reduction ironmaking carbon reduction method. The device comprises: a hybrid reforming unit, a direct reduction unit, a dust removal unit, and a dehumidification and decarburization unit connected in sequence by pipelines. The hybrid reforming unit is respectively provided with inlets for carbon-containing raw materials, a steam-rich oxidant, water vapor, and carbon dioxide gas. The dehumidification and decarburization unit is respectively provided with outlets for water, carbon dioxide, and circulating coal gas. The outlet for circulating coal gas is connected to the pipeline between the hybrid reforming unit and the direct reduction unit. The outlet for carbon dioxide on the dehumidification and decarburization unit is connected to the inlet for carbon dioxide gas on the hybrid reforming unit.

[0017] The direct reduction unit is connected to a heat exchange unit, which is connected to the water outlet of the dehumidification and decarbonization unit and the mixed reforming unit. The heat exchange unit is used to cool the direct reduced iron produced by the direct reduction unit through the water output by the dehumidification and decarbonization unit, so that the water output by the dehumidification and decarbonization unit is vaporized into water vapor input into the mixed reforming unit.

[0018] Optionally, the hybrid reforming unit is provided in two groups, and the two groups of hybrid reforming units are connected in series; or

[0019] The hybrid reforming units are provided in two groups, the two groups of hybrid reforming units are connected in parallel, and at least one group of the hybrid reforming units is connected to the heat exchange unit.

[0020] Optionally, the dust removal unit is a high-temperature dust removal unit, and a waste heat recovery unit is provided between the dust removal unit and the dehumidification and decarbonization unit. Part of the carbon dioxide output from the dehumidification and decarbonization unit enters the mixed reforming unit after passing through the waste heat recovery unit.

[0021] Optionally, a plasma heat source for heating is provided on the inlet of the carbonaceous raw material on the hybrid reforming unit and the outlet pipeline of the circulating coal gas on the dehumidification and decarbonization unit.

[0022] As described above, the steam-rich direct reduction ironmaking device and carbon reduction method of the present invention have the following beneficial effects:

[0023] In this scheme, the recycled gas, containing hydrogen, carbon monoxide, and other components, is generated during the direct reduction reaction by mixing it with crude synthesis gas for direct reduction, thus enabling the reuse of the top gas. The water obtained from the top gas after dust removal, dehumidification, and decarbonization is then vaporized through heat exchange to form water vapor, which, along with the generated carbon dioxide, can be used to generate crude synthesis gas. The reuse of recycled gas, water, and carbon dioxide establishes a closed hydrogen and carbon reaction system for direct iron reduction, significantly reducing raw material usage while increasing the proportion of hydrogen in the direct reduction reaction, thereby achieving efficient carbon reduction.

[0024] The reforming reaction of carbon-containing feedstock and steam-rich oxidant generates crude syngas, which is then mixed with recycled coal gas to produce reducing gas. Hydrogen accounts for a high proportion of the reducing gas, and most of the hydrogen comes from water rather than carbon-containing feedstock. Water can be recycled within the system, reducing the consumption of carbon-containing feedstock. Combined with the recycling of carbon dioxide, this system achieves synergistic carbon reduction by efficiently coupling feedstock consumption reduction with the hydrogen-carbon cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of the steam-rich direct reduction ironmaking device in Example 1 of the present invention.

[0026] Figure 2 This is a schematic structural diagram of the steam-rich direct reduction ironmaking device in Example 2 of the present invention.

[0027] Figure 3 This is a schematic structural diagram of the steam-rich direct reduction ironmaking device in Example 3 of the present invention.

[0028] Figure 4 It is a structural schematic diagram of the steam-rich direct reduction ironmaking device in the comparative example of the present invention. DETAILED DESCRIPTION

[0029] The reference numerals in the drawings of the specification include: hybrid reforming unit I, direct reduction unit II, dust removal unit III, dehumidification and decarbonization unit IV, heat exchange unit V, waste heat recovery unit VI, decarbonization unit VII, heating furnace VIII,

[0030] Carbon-containing raw materials 1, oxygen 2, external water supply 3, water vapor 4, top gas 5, dust removal gas 6, exhaust gas 7, carbon dioxide 8, water 9, circulating gas 10, crude synthesis gas 13, reducing gas 14, decarbonization gas 15, plasma heat source 16.

[0031] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0032] In an exemplary embodiment of the present application, a steam-rich direct reduction ironmaking and carbon reduction method is provided, which includes at least step S110 and step S120.

[0033] In step S110 , the carbon-containing raw material 1 and the steam-rich oxidant are reformed to generate a crude synthesis gas 13 . The steam-rich oxidant includes at least water vapor and an oxidant. The oxidant includes at least one of air, oxygen and carbon dioxide.

[0034] It should be noted that the steel industry is characterized by high temperatures, high dust content, and high impurity content, making it less adaptable to catalytic processes but more adaptable to non-catalytic processes. In particular, its high temperature characteristics are very beneficial for accelerating the hybrid reforming reaction process. Taking the gaseous hydrocarbon non-catalytic reformer as an example, the reforming reaction can be roughly summarized as follows: the non-catalytic methane steam reforming reaction is mainly based on reaction (1), and the CO2 dry reforming conversion reaction is mainly based on reaction (2).

[0035] CH4+H2O→CO+3H2 (1)

[0036] CH4+CO2→2CO+2H2 (2)

[0037] In step S120, the crude synthesis gas 13 and the circulating coal gas 10 are mixed to form a reducing gas 14, and a direct reduction reaction is carried out. The generated furnace top gas 5 is subjected to dust removal, dehumidification and decarbonization treatment to obtain water 9, carbon dioxide 8 and circulating coal gas 10. Part of the water 9 and carbon dioxide 8 are discharged to the outside, and the other part of the water 9 is vaporized into water vapor 4 after heat exchange treatment to be used to generate the crude synthesis gas 13.

[0038] It is worth noting that a non-traditional non-catalytic reforming reaction is adopted. Although the non-catalytic reforming reaction process does not require a catalyst, a catalyst can be selected to adjust the reforming reaction according to actual conditions. The reforming reaction can be a single or mixed reforming reaction of steam reforming and carbon dioxide 8 reforming, and the water 9 and carbon dioxide 8 produced by the direct reduction reaction can be returned as raw materials for the reforming reaction, thereby reducing the amount of carbon-containing raw materials 1 and thus reducing carbon emissions.

[0039] In this embodiment, the exhaust gas 7 discharged to the outside can be all of the carbon dioxide 8 and part of the water 9 output after the dehumidification and decarburization treatment, or can be part of the water 9 and part of the carbon dioxide 8 output after the dehumidification and decarburization treatment. In other words, the source of the carbon dioxide 8 in the oxidant can be entirely from the outside, part of the outside, part of the carbon dioxide 8 obtained after the dehumidification and decarburization treatment, or entirely from the carbon dioxide 8 obtained after the dehumidification and decarburization treatment.

[0040] For example, the top gas 5 is subjected to dust removal treatment to obtain dust-removed gas 6 , and the dust-removed gas 6 is subjected to dehumidification and decarbonization treatment to obtain water 9 , carbon dioxide 8 and circulating gas 10 , and the circulating gas 10 is mixed with the crude synthesis gas 13 to obtain reducing gas 14 .

[0041] In an exemplary embodiment, a reforming reaction is performed on a carbonaceous feedstock 1 and a steam-rich oxidant to generate a raw synthesis gas 13, comprising:

[0042] The water vapor 4 in the steam-rich oxidant is derived solely from the water 9 obtained by dust removal, dehumidification and decarbonization of the top gas 5;

[0043] or

[0044] Part of the water vapor 4 in the steam-rich oxidant comes from the external water supply 3, and part comes from the water 9 obtained by the dust removal, dehumidification and decarbonization treatment of the top gas 5; the external water supply 3 and the water 9 obtained by the dust removal, dehumidification and decarbonization treatment of the top gas 5 are vaporized together after heat exchange treatment to obtain water vapor 4.

[0045] It should be noted that the source of water vapor 4 for the reforming reaction can come only from the external water supply 3, or can be only the water 9 obtained after the top gas 5 is treated with dust removal, dehumidification and decarbonization, or can be both the external water supply 3 and the water 9 obtained after the top gas 5 is treated with dust removal, dehumidification and decarbonization.

[0046] In an exemplary embodiment, the carbon-containing raw material 1 is one or more of coal, biomass, liquid hydrocarbons, heavy oil, residual oil, natural gas, coalbed methane, shale gas, coke oven gas, coal-to-gas, and chemical tail gas.

[0047] Exemplarily, biomass includes wood, crop straw, livestock and poultry manure, etc.

[0048] Exemplary liquid hydrocarbons include naphtha, diesel, and the like.

[0049] In an exemplary embodiment, a reforming reaction is performed on a carbonaceous feedstock 1 and a steam-rich oxidant, comprising:

[0050] The reforming reaction is directly driven by high-temperature heat, and the reaction heat required for the reforming reaction comes from one or more of system self-heating, plasma heating, microwave heat, heat stored in heat storage body and industrial furnace heating, wherein the system self-heating includes at least the oxidation reaction heat of the carbon-containing raw material 1.

[0051] In this embodiment, the reforming reaction can be directly driven by high-temperature heat, rather than by conventional catalytic reforming. Depending on the actual situation, low-carbon external heating methods (such as plasma heating) or traditional heating methods (such as industrial furnaces) can be flexibly selected, significantly reducing sulfur sensitivity and equipment maintenance costs. The waste heat after reforming can be further utilized in direct reduction reactions, making it particularly suitable for the high-temperature, high-impurity steel industry. Furthermore, to improve reaction efficiency, catalytic reforming is included as an option. By adding a catalyst to the reforming reaction, the primary reaction is optimized and side reactions are reduced, thereby maximizing the single-pass utilization rate of the carbon-containing feedstock 1.

[0052] In an exemplary embodiment, part of the carbon dioxide 8 obtained by removing dust, dehumidifying and decarbonizing the top gas 5 is used as the oxidant.

[0053] In practical applications, the oxidant can be selected according to needs.

[0054] In this embodiment, part of the carbon dioxide 8 obtained by subjecting the top gas 5 to dust removal, dehumidification and decarbonization treatment is used as an oxidant, thereby achieving the reuse of the carbon dioxide 8.

[0055] In an exemplary embodiment, when water 9 is subjected to heat exchange treatment to generate water vapor 4 , the water 9 cools the direct reduced iron produced by the direct reduction reaction, so that the water 9 is vaporized into water vapor 4 .

[0056] In this embodiment, the waste heat of the direct reduced iron discharged from the furnace is utilized to vaporize the water 9 into the water vapor 4 .

[0057] like Figure 1 As shown, in an exemplary embodiment of the present application, a steam-rich direct reduction ironmaking device is further provided, which is applied to the above-mentioned steam-rich direct reduction ironmaking carbon reduction method. The device includes: a hybrid reforming unit I, a direct reduction unit II, a dust removal unit III, and a dehumidification and decarbonization unit IV connected in sequence by pipelines. The hybrid reforming unit I is respectively provided with inlets for a carbon-containing raw material 1, a steam-rich oxidant, water vapor 4, and a carbon dioxide 8 gas. The dehumidification and decarbonization unit IV is respectively provided with outlets for water 9, carbon dioxide 8, and a circulating coal gas 10. The outlet of the circulating coal gas 10 is connected to the pipeline between the hybrid reforming unit I and the direct reduction unit II. The outlet of the carbon dioxide 8 on the dehumidification and decarbonization unit IV is connected to the inlet of the carbon dioxide 8 gas on the hybrid reforming unit I.

[0058] The direct reduction unit II is connected to a heat exchange unit V, which is connected to the discharge outlet of the water 9 on the dehumidification and decarbonization unit IV and the mixed reforming unit I. The heat exchange unit V is used to cool the direct reduced iron produced by the direct reduction unit II through the water 9 output by the dehumidification and decarbonization unit IV, so that the water 9 output by the dehumidification and decarbonization unit IV is vaporized into water vapor 4 input to the mixed reforming unit I.

[0059] For example, the direct reduction unit II includes a shaft furnace with Figure 1 Where M is the ore raw material, HD is the hot direct reduced iron, and MD is the cooled direct reduced iron.

[0060] In this embodiment, carbon-containing feedstock 1, steam 4, and an oxidant enter the mixed reforming unit I for a reforming reaction, generating a crude mixed gas. This crude mixed gas is then mixed with circulating gas 10, which has been dehumidified and decarbonized by the dehumidification and decarbonization unit IV, to generate reducing gas 14. This reducing gas 14 enters the direct reduction unit II for a direct reduction reaction, producing direct reduced iron (DRI), which is then discharged as top gas 5. Top gas 5 is then dedusted by the dust removal unit III to produce dedusted gas 6. This dedusted gas 6 is then dehumidified and decarbonized by the dehumidification and decarbonization unit IV, where it is discharged as circulating gas 10, water 9, and carbon dioxide 8. The water 9 enters the heat exchange unit V to cool the DRI, vaporizing the water 9 to steam 4 before re-entering the mixed reforming unit I. The steam-rich mixed reforming unit I establishes a closed reaction system of hydrogen and carbon required for the direct reduction reaction, significantly reducing raw material usage while increasing the hydrogen ratio in the DRI reaction, thereby achieving efficient carbon reduction. Specifically, a large amount of reforming reaction of carbon-containing raw materials 1 and water vapor 4 occurs in the hybrid reforming unit I (refer to reaction formula (1), and the proportion of hydrogen in the generated reducing gas 14 is relatively high, and most of the hydrogen comes from water 9 rather than the carbon-containing raw materials 1. Water 9 can be recycled in the system, thereby reducing the consumption of carbon-containing raw materials 1. In addition, the hybrid reforming unit I can also recycle the carbon dioxide 8 in the system (refer to reaction formula (2). In short, by constructing an efficient coupling of raw material consumption reduction and hydrogen-carbon cycle, synergistic carbon reduction can be achieved.

[0061] This embodiment is not limited to traditional catalytic reforming and can utilize high-temperature heat to directly drive the reforming reaction. Depending on the actual situation, low-carbon external heating methods (such as plasma heating) or traditional heating methods (such as industrial furnaces) can be flexibly selected, significantly reducing sulfur sensitivity and equipment maintenance costs. The waste heat after reforming can be further utilized in direct reduction reactions, which is particularly applicable to the high-temperature, high-impurity steel industry. Furthermore, to improve reaction efficiency, catalytic reforming is included as an option. By adding a catalyst to the reforming unit, the main reaction is optimized and side reactions are reduced to maximize the single-pass utilization rate of the carbon-containing feedstock 1.

[0062] Furthermore, cost reduction and efficiency improvement are achieved through synergy among the system's units. The waste heat from the direct reduction unit II reaction is used to re-vaporize the water 9 produced within the system as an oxidant and hydrogen source for the reforming unit, reducing external heat supply. The coal gas from the direct reduction unit II is subjected to high-temperature dust removal to minimize heat loss from the system to the outside world.

[0063] In an exemplary embodiment, two groups of hybrid reforming units I are provided, and the two groups of hybrid reforming units I are connected in series;

[0064] or

[0065] There are two groups of hybrid reforming units I, which are connected in parallel, and at least one group of hybrid reforming units I is connected to the heat exchange unit V.

[0066] In this embodiment, the number of hybrid reforming units I can be set according to demand.

[0067] It should be noted that when the hybrid reforming unit I is provided in two groups, the two groups of hybrid reforming units I can be provided in series or in parallel.

[0068] In an exemplary embodiment, the dust removal unit III is a high-temperature dust removal unit, and a waste heat recovery unit VI is provided between the dust removal unit III and the dehumidification and decarbonization unit IV. Part of the carbon dioxide 8 output from the dehumidification and decarbonization unit IV enters the mixed reforming unit I after passing through the waste heat recovery unit VI.

[0069] It is worth noting that the dust removal unit III can be set to single-stage dust removal or multi-stage dust removal according to needs.

[0070] For example, a plasma heat source 16 may be provided on the pipeline of the circulating coal gas and the carbonaceous raw material for heating, or a heat source may not be provided separately, and the raw material may be directly preheated by the heat exchange unit V or the like.

[0071] Example 1

[0072] like Figure 1 As shown, in Example 1, the hybrid reforming unit I is a methane steam reforming furnace, the steam source is the external water supply 3 and part of the water 9 of the dehumidification and decarbonization unit VII is vaporized by the heat exchange unit V, and part of the system exhaust gas (water 9 and carbon dioxide 8 output by the dehumidification and decarbonization unit IV) is output to the outside.

[0073] After the natural gas is heated to a temperature above 1500°C by the plasma heat source 16, it is fed into the mixed reforming unit together with steam in a ratio of 1:1. After the non-catalytic methane steam reforming reaction, a crude synthesis gas with a hydrogen-carbon ratio (H2 / CO) of 1300°C is obtained. The circulating coal gas from the dehumidification and decarbonization unit is heated to 900°C by the plasma heat source 16 and mixed with the crude synthesis gas to obtain a reducing gas with a hydrogen-carbon ratio of 3.3 and a temperature of 1000°C. The top coal gas after the direct reduction reaction of the reducing gas in the direct reduction unit is successively subjected to dust removal, dehumidification and decarbonization treatment in the dust removal unit and the dehumidification and decarbonization unit before being reused or discharged. The total carbon dioxide output to the outside of the system is 0.11t.CO2 / t.DRI, and the natural gas consumption is 82.3Nm 3 / t.DRI.

[0074] Example 2

[0075] like Figure 2 As shown, the difference between Example 2 and Example 1 is that the only source of steam for the reforming reaction is the water 9 in the dehumidification and decarbonization unit IV, which is vaporized into water vapor 4 by the heat exchange unit V (or direct reduced iron cooling unit), while the rest remains unchanged. The total carbon dioxide output to the outside of the system is 0.11t.CO2 / t.DRI, and the natural gas consumption is 82.3Nm 3 / t.DRI.

[0076] Example 3

[0077] like Figure 3 As shown, the difference between Example 3 and Example 1 is that a waste heat recovery unit VI is provided between the dehumidification unit and the dehumidification and decarbonization unit IV, and the carbon dioxide 8 output by the dehumidification and decarbonization unit IV is heated by the waste heat recovery unit VI and then returned to the mixed reforming unit I. The only source of steam for the reforming reaction is part of the water 9 in the dehumidification and decarbonization unit IV, which is vaporized into steam by the heat exchange unit V. Part of the carbon dioxide 8 in the dehumidification and decarbonization unit IV is heated by the waste heat recovery unit VI and then returned to the mixed reforming unit I for reuse. Non-catalytic methane steam reforming and methane carbon dioxide 8 reforming reactions occur in the mixed reforming unit I, and the rest remain unchanged. The entire system outputs carbon dioxide to the outside world at a rate of ~0.11t.CO2 / t.DRI, and the natural gas consumption is 81.8Nm 3 / t.DRI.

[0078] Comparative Example

[0079] like Figure 4As shown, the difference between the comparative example and Example 1 is that in the comparative example, the carbon-containing feedstock 1 and oxygen 2 are preheated in waste heat recovery unit VI before being passed to the hybrid reforming unit I to generate a crude mixed gas. The crude mixed gas is then mixed with decarbonized gas 15 heated in heating furnace VIII to generate reducing gas 14. Reducing gas 14 then enters direct reduction unit II for direct reduction. The top gas 5 generated by the direct reduction reaction is sequentially passed through dust removal unit III, waste heat recovery unit VI, and decarbonization unit VII for dust removal, heat exchange, and decarbonization. The desorbed gas generated after decarbonization is discharged to the environment. The decarbonized gas 15 generated after decarbonization enters heating furnace VIII for heating before being mixed with the crude mixed gas to generate the crude mixed gas. Among them, the top gas 5 is treated by the dust removal unit III and the waste heat recovery unit VI and then enters the decarbonization unit VII for treatment to obtain a decarbonized gas 15 with a carbon dioxide 8 content of about 1.9% and an effective gas content of about 95%. The decarbonized gas 15 is heated to about 900°C by the heating furnace VIII and then mixed with the crude synthesis gas 13 at the outlet of the converter (mixed reforming unit I) to obtain a reducing gas 14 with an effective gas content of about 88% and a temperature of about 950°C. The carbon entering the system is discharged to the outside through the desorption gas of the decarbonization unit VII. The carbon dioxide 8 output by the desorption gas to the outside is about 0.9t.CO2 / t.DRI, and the natural gas consumption is about 260Nm 3 / t.DRI.

[0080] In summary, the carbon dioxide emissions in Examples 1-3 were only 0.11 tCO₂ / tDRI, a reduction of 87.8% compared to 0.9 tCO₂ / tDRI in the comparative example, and natural gas consumption was reduced by 68.5%. This shows that compared to traditional hydrogen-based shaft furnace ironmaking methods, the carbon reduction method of the present invention significantly reduces carbon dioxide emissions and feed gas consumption.

[0081] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A steam-rich direct reduction ironmaking carbon reduction method, characterized in that: include: reforming a carbonaceous feedstock and a steam-rich oxidant to generate a crude synthesis gas, wherein the steam-rich oxidant comprises at least water vapor and an oxidant, and the oxidant comprises at least one of air, oxygen, and carbon dioxide; The crude synthesis gas is mixed with the circulating coal gas to form reducing gas, and a direct reduction reaction is carried out. The generated furnace top gas is subjected to dust removal, dehumidification and decarbonization treatment to obtain water, carbon dioxide and the circulating coal gas. Part of the water and carbon dioxide are discharged to the outside, and the other part of the water is vaporized into water vapor after heat exchange treatment to be used to generate crude synthesis gas.

2. The method for reducing carbon in ironmaking by direct reduction using rich steam according to claim 1, characterized in that: The carbon-containing raw material and the steam-rich oxidant are reformed to generate a raw synthesis gas, including: The water vapor in the steam-rich oxidant comes only from the water obtained by dust removal, dehumidification and decarbonization of the top gas; or Part of the water vapor in the steam-rich oxidant comes from external water supply, and part comes from water obtained by dust removal, dehumidification and decarbonization treatment of the top gas; the external water supply and the water obtained by dust removal, dehumidification and decarbonization treatment of the top gas are vaporized together after heat exchange treatment to obtain water vapor.

3. The method for reducing carbon in ironmaking by direct reduction using rich steam according to claim 1, characterized in that: The carbon-containing raw material is one or more of coal, biomass, liquid hydrocarbons, heavy oil, residual oil, natural gas, coalbed methane, shale gas, coke oven gas, coal-to-gas and chemical tail gas.

4. The method for reducing carbon in ironmaking by direct reduction using rich steam according to claim 1, characterized in that: The carbonaceous feedstock and the steam-rich oxidant are subjected to a reforming reaction, including: The reforming reaction is directly driven by high-temperature heat, and the reaction heat required for the reforming reaction comes from one or more of system self-heating, plasma heating, microwave heat, heat stored in a heat storage body, and industrial furnace heating, wherein the system self-heating at least includes the oxidation reaction heat of the carbon-containing raw material.

5. The method for reducing carbon in ironmaking by direct reduction using rich steam according to claim 1, characterized in that: Part of the carbon dioxide obtained by removing dust, dehumidifying and decarbonizing the top gas is used as the oxidant.

6. The method for carbon reduction in ironmaking by direct reduction with rich steam according to any one of claims 1 to 5, characterized in that: When water is processed by heat exchange to generate water vapor, the water cools the direct reduced iron produced by the direct reduction reaction, causing the water to be vaporized into water vapor.

7. A steam-rich direct reduction ironmaking device, characterized in that: The method for reducing carbon in ironmaking by direct reduction of rich steam as claimed in any one of claims 1 to 6 comprises: a hybrid reforming unit, a direct reduction unit, a dust removal unit and a dehumidification and decarbonization unit connected in sequence by pipelines, the hybrid reforming unit being provided with inlets for a carbon-containing raw material, a rich steam oxidant, water vapor and carbon dioxide gas, respectively; the dehumidification and decarbonization unit being provided with outlets for water, carbon dioxide and circulating coal gas, respectively; the outlet for circulating coal gas being connected to a pipeline between the hybrid reforming unit and the direct reduction unit; and the outlet for carbon dioxide on the dehumidification and decarbonization unit being connected to an inlet for carbon dioxide gas on the hybrid reforming unit; The direct reduction unit is connected to a heat exchange unit, which is connected to the water outlet of the dehumidification and decarbonization unit and the mixed reforming unit. The heat exchange unit is used to cool the direct reduced iron produced by the direct reduction unit through the water output by the dehumidification and decarbonization unit, so that the water output by the dehumidification and decarbonization unit is vaporized into water vapor input into the mixed reforming unit.

8. The rich steam direct reduction ironmaking device according to claim 7, characterized in that: The hybrid reforming unit is provided in two groups, and the two groups of hybrid reforming units are connected in series; or The hybrid reforming units are provided in two groups, the two groups of hybrid reforming units are connected in parallel, and at least one group of the hybrid reforming units is connected to the heat exchange unit.

9. The rich steam direct reduction ironmaking device according to claim 7, characterized in that: The dust removal unit is a high-temperature dust removal unit. A waste heat recovery unit is provided between the dust removal unit and the dehumidification and decarbonization unit. Part of the carbon dioxide output from the dehumidification and decarbonization unit enters the mixed reforming unit after passing through the waste heat recovery unit.

10. The rich steam direct reduction ironmaking device according to any one of claims 7 to 9, characterized in that: The inlet of the carbon-containing raw material on the hybrid reforming unit and the outlet pipeline of the circulating coal gas on the dehumidification and decarbonization unit are provided with a plasma heat source for heating.

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