Chemical self-heating reduction metallurgy method based on gas component regulation and control

Abstract

The invention provides a chemical self-heating reduction metallurgy method based on gas component regulation and control, and belongs to the technical field of reduction metallurgy. The method comprises the following steps: acquiring carbon dioxide and water vapor in a first preset volume ratio; performing reforming reaction on the carbon dioxide and the water vapor according to the first preset volume ratio and methane to generate carbon monoxide and hydrogen according to a second preset volume ratio; and carrying out reduction reaction on the iron ore according to the carbon monoxide and the hydrogen in a second preset volume ratio to realize chemical self-heating reduction to generate the reduced iron.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of reduction metallurgy, and more particularly, to a chemical self-heating reduction metallurgy method based on gas component regulation. BACKGROUND

[0002] The steel industry is one of the largest carbon emitters in the world. The traditional blast furnace-converter steelmaking process relies on coke and coal as reducing agents and fuels, and has high carbon emission intensity, with about 1.8-2.2 tons of carbon emissions per ton of crude steel , which is difficult to meet the requirements of low-carbon development.

[0003] To achieve low-carbon metallurgy, gas-based direct reduction technology has attracted widespread attention. Compared with the blast furnace process, this technology has higher energy efficiency, lower emissions, and is particularly suitable for areas rich in natural gas resources or where green hydrogen is readily available. Among them, the MIDREX process is the most mature and widely used gas-based direct reduction technology, accounting for more than 80% of global direct reduced iron (DRI) production capacity.

[0004] However, with the development of hydrogen metallurgy, increasing the proportion of hydrogen in the reducing gas has become a key path to reduce carbon emissions. However, the reduction of iron oxides is a strong endothermic reaction, and the shaft furnace operates close to quasi-adiabatic conditions, making it difficult to effectively supplement external heat, resulting in difficulty in maintaining the heat balance in the furnace under hydrogen-rich conditions. Currently, two heat supplement methods are mainly used: one is excess sensible heat supply, that is, heating more reducing gas to carry sensible heat into the furnace, but this leads to an increase in gas circulation, an increase in compression energy consumption, and a decrease in system efficiency; the other is oxygen injection partial combustion heat supply, which heats the furnace by local combustion

[0005] or CO heat release, although the heating effect is obvious, but it is easy to cause uneven temperature distribution, local overheating, and irreversible system loss, and increases the complexity of equipment and operating costs. SUMMARY

[0006] Therefore, the present disclosure provides a chemical self-heating reduction metallurgy method based on gas component regulation, which can at least partially solve the above technical problems.

[0007] One aspect of the present disclosure provides a chemical self-heating reduction metallurgy method based on gas component regulation, comprising: obtaining a first predetermined volume ratio of carbon dioxide and water vapor; performing a reforming reaction based on the first predetermined volume ratio of carbon dioxide and water vapor and methane to generate; performing a reduction reaction on iron ore according to a second predetermined volume ratio of carbon monoxide and hydrogen to achieve chemical self-heating reduction to generate reduced iron. ​

[0008] According to embodiments of this disclosure, the reforming reaction includes a dry reforming reaction and a steam reforming reaction; a reforming reaction is carried out with methane based on a first preset volume ratio of carbon dioxide and water vapor to generate carbon monoxide and hydrogen in a second preset volume ratio, including: a dry reforming reaction of carbon dioxide and methane; a steam reforming reaction of water vapor and methane; and the volume ratio of output carbon monoxide and hydrogen is controlled to the second preset volume ratio by adjusting the ratio of the dry reforming reaction to the steam reforming reaction.

[0009] According to an embodiment of this disclosure, obtaining a first preset volume ratio of carbon dioxide and water vapor includes: obtaining a recovered gas after an iron ore reduction reaction, the recovered gas including carbon dioxide and water vapor; and dehydrating the recovered gas to obtain a first preset volume ratio of carbon dioxide and water vapor.

[0010] According to embodiments of this disclosure, the recovered gas is dehydrated by using silica gel to obtain carbon dioxide and water vapor in a first preset volume ratio.

[0011] According to an embodiment of this disclosure, the first preset volume ratio is (1.2~6):1.

[0012] According to an embodiment of this disclosure, the second preset volume ratio is (0.3~1.2):1.

[0013] According to embodiments of this disclosure, the method further includes: condensing the top gas generated after the reduction reaction of iron ore, the top gas including a recovered gas, the recovered gas further including at least a portion of unreacted hydrogen and at least a portion of unreacted carbon monoxide; and using the residual heat of the recovered gas to regenerate silica gel.

[0014] According to embodiments of this disclosure, the top gas further includes a combustion gas, which is at least partially unreacted hydrogen and at least partially unreacted carbon monoxide; at least partially unreacted hydrogen and at least partially unreacted carbon monoxide are obtained after the reduction reaction of iron ore; the heat generated by burning the at least partially unreacted hydrogen and at least partially unreacted carbon monoxide provides heat for the reforming reaction.

[0015] According to embodiments of this disclosure, the method further includes using the heat generated from the combustion of methane to provide heat for the reforming reaction.

[0016] The second aspect of this disclosure provides a gas-based direct reduction metallurgical method, in which metallurgy is performed using any of the methods described above.

[0017] The chemical autothermal reduction metallurgical method based on gas composition regulation provided in the embodiments of this disclosure has at least the following beneficial effects:

[0018] By adjusting the ratio of carbon dioxide to water vapor, the dry reforming and steam reforming reactions of methane are controlled in a coordinated manner, and the reducing gas content is precisely adjusted. Volume ratio to compensate for the exothermic reaction of CO reduction. The reduction process is endothermic, achieving self-heating balance within the vertical furnace, reducing reliance on external heating and excessive circulating gas, lowering system energy consumption and energy loss, and improving the energy efficiency and stability of the hydrogen metallurgical process. Attached Figure Description

[0019] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0020] Figure 1 A flowchart illustrating a metallurgical method according to an embodiment of the present disclosure is shown schematically.

[0021] Figure 2 Different embodiments according to this disclosure are illustrated schematically. Thermal effect diagram of volume ratio. Detailed Implementation

[0022] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0024] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0025] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0026] Figure 1 A flowchart illustrating a metallurgical method according to an embodiment of the present disclosure is shown schematically.

[0027] like Figure 1 As shown, the method of this embodiment includes: obtaining carbon dioxide and water vapor in a first preset volume ratio; reacting the carbon dioxide and water vapor in the first preset volume ratio with methane in a reforming reaction to generate carbon monoxide and hydrogen in a second preset volume ratio; and using the carbon monoxide and hydrogen in the second preset volume ratio to perform a reduction reaction on iron ore, achieving a chemical autothermal reduction to generate reduced iron.

[0028] In embodiments of this disclosure, in the conventional MIDREX process, natural gas is reformed and reacted with steam or... A reforming reaction occurs, producing... The reducing gas is mainly composed of CO. It is introduced from the bottom of the vertical shaft furnace and comes into countercurrent contact with the iron ore pellets moving downwards, gradually reducing the iron oxides (…). The reforming process involves reducing the raw material to direct reduced iron (DRI). After dust removal, cooling, and partial condensation and dehydration, the top gas from the vertical shaft furnace is divided into two paths: one path is used as fuel for combustion to provide heat for the reforming process; the other path is recycled back to the reformer inlet as recoverable gas to mix with fresh natural gas, thereby reducing feedstock consumption.

[0029] However, The reduction of iron oxides is a strongly endothermic reaction, while the vertical furnace operates under near-adiabatic conditions, making it difficult to effectively replenish external heat. This results in the inability to maintain the thermal balance inside the furnace under hydrogen enrichment conditions.

[0030] In the reduction process of iron oxides to direct replacement of primary iron: The reduction reaction is strongly endothermic; the CO reduction reaction is weakly exothermic; especially the reduction stage of FeO→Fe.

[0031]

[0032]

[0033] Currently, two main methods of supplementary heating are used: one is excessive sensible heat supply, which heats more reducing gas to carry sensible heat into the furnace, but this leads to an increase in gas circulation volume, increased compression energy consumption, and decreased system efficiency; the other is partial combustion heating via oxygen injection, which uses localized combustion... While CO can release heat and provide significant heating, it can also lead to uneven temperature distribution, localized overheating, and irreversible heat loss, while increasing equipment complexity and operating costs.

[0034] Based on this, this embodiment controls the methane reforming reaction synergistically by adjusting the ratio of carbon dioxide to water vapor, and precisely regulates the reducing gas. Volume ratio, utilizing the exothermic nature of the CO reduction reaction to compensate. The endothermic requirements of the reduction process achieve chemical self-heating equilibrium within the vertical shaft furnace, fundamentally reducing reliance on excess gas circulation carrying sensible heat or oxygen injection combustion for supplemental heating. This method effectively reduces the gas circulation volume and reformer heat load, decreasing natural gas consumption and compressor energy consumption, thereby significantly reducing overall system energy consumption and equipment operating load. Simultaneously, it avoids temperature unevenness and irreversible energy loss caused by localized combustion, significantly improving energy utilization efficiency and efficiency. Furthermore, due to the reduction in top gas consumption for combustion heating, the amount of combustion exhaust gas and... The corresponding reduction in emissions has significant benefits in terms of energy conservation, consumption reduction, and environmental protection, and is of great importance in promoting the development of gas-based direct reduction technology towards low-carbon and high-efficiency directions.

[0035] like Figure 1 The diagram shows the direct reduced iron (DRI) production process using methane reforming and combustion heating. Methane is converted into methane rich in... The reducing gas from CO is used for the reduction reaction of iron ore; simultaneously, the high-temperature flue gas generated by the combustion of methane in the combustion chamber provides heat for the reforming reaction, forming a self-supplied heat energy mechanism. The top gas generated during the vertical shaft furnace reduction process, after condensation, dust removal, and deep dehydration, is reintroduced into the system as recovered gas, which not only reduces external raw material consumption but also improves overall energy utilization efficiency. Compared to the traditional MIDREX baseline operating condition without a dehydration device for the recovered gas, this embodiment achieves chemical self-heating through component control, reducing external heating requirements and decreasing the gas circulation volume by approximately 25% compared to the baseline operating condition; reducing reformer fuel consumption by approximately 15%; increasing efficiency from approximately 71% in the baseline operating condition to approximately 74%; and increasing gas utilization rate from approximately 34% to approximately 44%.

[0036] Based on the above embodiments, the reforming reaction includes dry reforming reaction and steam reforming reaction.

[0037] Based on a first preset volume ratio, carbon dioxide and water vapor undergo a reforming reaction with methane to produce carbon monoxide and hydrogen in a second preset volume ratio. This includes: a dry reforming reaction of carbon dioxide with methane; and a steam reforming reaction of water vapor with methane. By adjusting the ratio of the dry reforming reaction to the steam reforming reaction, the volume ratio of the output carbon monoxide and hydrogen is controlled to the second preset volume ratio.

[0038] In embodiments of this disclosure, the dry reforming reaction is as follows: .

[0039] The steam reforming reaction is as follows: .

[0040] By separately adjusting the input ratio of carbon dioxide and water vapor, the extent of the dry reforming and steam reforming reactions of methane can be controlled synergistically. This is because the reducing gas produced during dry reforming contains... The ratio is close to 1:1, while steam reforming produces hydrogen-rich gas. The ratio is approximately 3:1. By adjusting the relative proportions of the two reactions, the output reducing gas can be precisely controlled. The volume ratio of CO to the reducing gas is the second preset volume ratio required. This method allows for flexible customization of the reducing gas composition, providing conditions for subsequent chemical autothermal reduction in the vertical shaft furnace, that is, utilizing the exothermic characteristics of CO reducing iron oxides to compensate for... The strong endothermic demand of the reduction process reduces external heating and excessive gas circulation, thereby improving the system's thermal efficiency and energy utilization level.

[0041] Based on the above embodiments, obtaining carbon dioxide and water vapor in a first preset volume ratio includes: obtaining the recovered gas after the iron ore reduction reaction, the recovered gas including carbon dioxide and water vapor; and dehydrating the recovered gas to obtain carbon dioxide and water vapor in a first preset volume ratio.

[0042] In the embodiments of this disclosure, the recovered gas from the iron ore reduction reaction is used as a source of carbon dioxide and water vapor, and the recovered gas is dehydrated to obtain a predetermined ratio. The mixed gas not only enables the effective reuse of useful components in the reduction products but also avoids the need for external reagent addition. This method fully utilizes the material flow circulation within the system, reducing raw material and energy consumption; simultaneously, precise control of the degree of dehydration allows for flexible adjustment. Volume ratio, which is the reducing gas in the subsequent reforming reaction. Precise control of the ratio provides a guarantee and further supports the autonomous maintenance of thermal balance within the vertical furnace.

[0043] Based on the above embodiments, the recovered gas is dehydrated, including: using silica gel to dehydrate the recovered gas to obtain carbon dioxide and water vapor in a first preset volume ratio.

[0044] Furthermore, the volume of water vapor in the recovered gas can be reduced from 15 vol% to 5 vol%. At this point, the recovered gas enters the reformer, enhancing the dry reforming reaction and increasing the CO content in the generated gas; ultimately, reduced gas is achieved. Component regulation.

[0045] Based on the above embodiments, the first preset volume ratio is (1.2~6):1.

[0046] Based on the above embodiments, the second preset volume ratio is (0.3~1.2):1.

[0047] Based on the above embodiments, the method further includes: condensing the top gas generated after the reduction reaction of iron ore, wherein the top gas includes a recovered gas, and the recovered gas further includes at least a portion of unreacted hydrogen and at least a portion of unreacted carbon monoxide; and using the residual heat of the recovered gas to regenerate silica gel.

[0048] In the embodiments of this disclosure, the top gas generated after the reduction reaction of iron ore is condensed, and the low-grade waste heat generated during the cooling process of the recovered gas is used to regenerate the silica gel adsorbent, thus achieving cascade utilization of waste heat. Simultaneously, the recovered gas also includes at least some unreacted hydrogen and at least some unreacted carbon monoxide, enabling efficient recycling of resources.

[0049] According to embodiments of this disclosure, the top gas further includes a combustion gas, which is at least partially unreacted hydrogen and at least partially unreacted carbon monoxide; at least partially unreacted hydrogen and at least partially unreacted carbon monoxide are obtained after the reduction reaction of iron ore; the heat generated by burning the at least partially unreacted hydrogen and at least partially unreacted carbon monoxide provides heat for the reforming reaction.

[0050] Furthermore, this also includes using the heat generated from the combustion of methane to provide heat for the reforming reaction.

[0051] In the embodiments of this disclosure, the top gas contains some unreacted hydrogen and carbon monoxide, which are recovered and burned as combustion gases. The heat released from this combustion provides the necessary high-temperature heat for the reforming reaction, achieving efficient utilization of the reducing agent and self-sufficiency in energy, significantly reducing external energy consumption. Simultaneously, when the heat released from the combustion of the top gas is insufficient to heat the reforming reaction, it is combined with methane combustion for heating, allowing for flexible adjustment of the heat input intensity and ensuring stable operation of the reforming process. This multi-source synergistic heating method not only improves the system's thermal integration and energy utilization efficiency but also reduces reducing gas waste and carbon emissions.

[0052] This disclosure provides a gas-based direct reduction metallurgical method, employing any of the methods described above. The principle of the gas composition-controlled chemical autothermal reduction metallurgical method of this embodiment has been described in detail above and will not be repeated here.

[0053] Furthermore, metallurgy can be carried out in the MIDREX process or the Eichelm Direct Reduction Process (HYL) using any of the above-mentioned chemical autothermal reduction metallurgical methods based on gas composition control.

[0054] Figure 2 The diagram illustrates the thermal effects of different CO / H2 volume ratios according to embodiments of the present disclosure.

[0055] like Figure 2 As shown, when the CO / H2 ratio is low (close to 0), the reactor requires a large amount of external heat input (positive heat demand) to maintain the high-temperature environment required for the reduction process. This is because the reducing gas at this point is mainly composed of hydrogen, and the reduction of iron ore by hydrogen is an endothermic reaction, requiring additional heat to compensate. As the CO / H2 ratio gradually increases, the reactor's heat demand decreases rapidly and eventually turns negative (i.e., heat is released). This is because the reduction of iron ore by carbon monoxide is an exothermic reaction, generating enough heat to compensate for the endothermic effect in the hydrogen reduction process, even exceeding the required amount, thus achieving self-heating equilibrium. Meanwhile, a comparison of curves under different temperature conditions shows that as the reducing gas temperature increases, the CO / H2 ratio required for the reactor to reach self-heating equilibrium decreases. For example, at 850°C, the CO / H2 ratio required for the reactor's heat demand to drop to zero is significantly higher than that at 950°C. This means that at higher temperatures, even with a relatively low CO / H2 ratio, self-heating equilibrium can be achieved more quickly, further reducing reliance on excess gas circulation or external heating.

[0056] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A chemical autothermal reduction metallurgical method based on gas composition regulation, characterized in that, include: Obtain carbon dioxide and water vapor in a first preset volume ratio; Based on the first preset volume ratio of carbon dioxide and water vapor, a reforming reaction is carried out with methane to generate a second preset volume ratio of carbon monoxide and hydrogen. The iron ore is reduced by a chemical autothermal reduction reaction based on the second preset volume ratio of carbon monoxide and hydrogen to generate reduced iron.

2. The method according to claim 1, characterized in that, The reforming reaction includes dry reforming and steam reforming; The reforming reaction of carbon dioxide and water vapor with methane based on a first preset volume ratio to generate carbon monoxide and hydrogen in a second preset volume ratio includes: The carbon dioxide and methane undergo the dry reforming reaction; The water vapor undergoes the steam reforming reaction with methane; By adjusting the ratio of the dry reforming reaction to the steam reforming reaction, the volume ratio of the output carbon monoxide and hydrogen is adjusted to a second preset volume ratio.

3. The method according to claim 1, characterized in that, The process of obtaining carbon dioxide and water vapor in a first preset volume ratio includes: Obtain the recovered gas after the reduction reaction of the iron ore, wherein the recovered gas includes carbon dioxide and water vapor; The recovered gas is dehydrated to obtain carbon dioxide and water vapor in a first preset volume ratio.

4. The method according to claim 3, characterized in that, The dehydration treatment of the recovered gas includes: The recovered gas is dehydrated using silica gel to obtain carbon dioxide and water vapor in a first preset volume ratio.

5. The method according to claim 3, characterized in that, The first preset volume ratio is (1.2~6):

1.

6. The method according to claim 1, characterized in that, The second preset volume ratio is (0.3~1.2):

1.

7. The method according to claim 4, characterized in that, Also includes: The top gas generated after the reduction reaction of the iron ore is condensed. The top gas includes the recovered gas, which further includes at least some unreacted hydrogen and at least some unreacted carbon monoxide. The silica gel is regenerated using the residual heat of the recovered gas.

8. The method according to claim 7, characterized in that, The top gas also includes combustion gases, which are at least partially unreacted hydrogen and at least partially unreacted carbon monoxide; Obtain at least some unreacted hydrogen and at least some unreacted carbon monoxide after the reduction reaction of the iron ore; The heat generated by burning at least some of the unreacted hydrogen and at least some of the unreacted carbon monoxide provides heat for the reforming reaction.

9. The method according to claim 8, characterized in that, Also includes: The heat generated from the combustion of methane provides heat for the reforming reaction.

10. A gas-based direct reduction metallurgical method, characterized in that, Metallurgy is carried out using the method described in any one of claims 1 to 9.

Images