Hydrogen-based pre-reduction system and method for smelting reduction ironmaking ore powder

Abstract

The invention relates to a hydrogen-based pre-reduction system and method for smelting reduction ironmaking ore powder, and belongs to the technical field of iron ore preparation. The hydrogen-based pre-reduction system comprises a drying and preheating unit used for obtaining hot ore with a first set temperature; the hydrogen preparation and temperature regulation unit is used for obtaining hydrogen with a second set temperature; the multi-stage fluidized bed pre-reduction unit is used for carrying out two-stage pre-reduction reaction on the hot ore and hydrogen to obtain pre-reduced iron ore; the smelting reduction final smelting unit is used for performing final smelting reduction reaction on the pre-reduced iron ore; and the energy circulating system is used for recovering the flue gas generated in the smelting reduction furnace and using the flue gas as a heat source of hydrogen and hot ore through the heat exchanger, so that the flue gas is recycled, the energy waste is reduced, and the overall carbon emission of the system is reduced. The technical scheme provided by the invention is efficient, energy-saving, low-carbon and environment-friendly, continuous production can be realized, meanwhile, the production efficiency is improved, the production cost is reduced, and the green smelting concept is met.

Description

Technical Field

[0001] This application relates to the technical field of reduced ironmaking, and particularly to a hydrogen-based pre-reduction system and method for smelting iron ore powder by smelting reduction. Background Art

[0002] In order to reduce carbon emissions during ironmaking, the short-process smelting reduction ironmaking technology is usually adopted. This technology uses anthracite as a reducing agent and pre-reduces iron ore through a coal-based rotary kiln process. Through actual operation tests, under the condition that the reduction time does not exceed 40 minutes, the highest reduction rate of iron ore can only reach 25%, showing a poor reduction effect; while when the reduction rate of iron ore reaches 60%, the reduction time needs to exceed 100 minutes, which results in extremely low operating efficiency of the production line. In this case, the carbon dioxide emissions per ton of iron in the drying and pre-reduction processes can be as high as 423.42 kg. Therefore, in order to further reduce carbon emissions in the drying and pre-reduction processes, finding a more reasonable and environmentally friendly process method has become the focus of attention of the academic community and experts. Summary of the Invention

[0003] This application provides a hydrogen-based pre-reduction system and method for smelting iron ore powder by smelting reduction to solve the following technical problems: how to efficiently smelt iron while reducing carbon emissions.

[0004] In a first aspect, an embodiment of this application provides a hydrogen-based pre-reduction system for smelting iron ore powder by smelting reduction, including:

[0005] A drying and preheating unit for heating the iron ore to obtain hot ore with a first set temperature;

[0006] A hydrogen production and temperature adjustment unit including a hydrogen production module and a heat exchanger for recovering waste heat from flue gas, for producing and heating hydrogen to obtain hydrogen with a second set temperature;

[0007] A multi-stage fluidized bed pre-reduction unit adopting a structure of a first circulating fluidized bed and a second circulating fluidized bed connected in series, for receiving the hot ore with the first set temperature and the hydrogen with the second set temperature to carry out two-stage reduction reactions to obtain pre-reduced hot ore;

[0008] A smelting reduction final smelting unit including a smelting reduction furnace and a hydrogen-rich fuel injection system, for hot charging the pre-reduced hot ore into the smelting reduction furnace for final reduction reactions;

[0009] An energy recycling system including a flue gas three-stage treatment module connected in sequence, wherein,

[0010] The first-stage treatment module is connected to the flue gas discharge port of the smelting reduction furnace, and the high-temperature flue gas in the smelting reduction furnace is passed through the first-stage treatment and then introduced into the heat exchanger;

[0011] The secondary treatment module is connected to the flue gas outlet of the heat exchanger, and conveys the cooled flue gas in the heat exchanger to the air inlet of the drying and preheating unit;

[0012] The tertiary treatment module is connected to the exhaust port of the drying and preheating unit, and purifies the flue gas at the exhaust port to meet the emission standards.

[0013] Optionally, the hydrogen-rich fuel injection system includes a hot ore storage bin and a hot ore injection device. The hot ore storage bin is connected to the multi-stage fluidized bed pre-reduction unit and is used to receive and store pre-reduced hot ore; the hot ore injection device is used to load the pre-reduced hot ore in the hot ore storage bin into the smelting reduction furnace.

[0014] Optionally, the primary treatment module includes a first dust removal device connected in series, and the first dust removal device is used to remove dust in the high-temperature flue gas in the smelting reduction furnace; and / or,

[0015] The tertiary treatment module includes a second dust removal device and a desulfurization and denitrification device connected in series. The second dust removal device is connected to the exhaust port of the drying and preheating unit and is used to remove dust in the flue gas generated by the drying and preheating unit; the desulfurization and denitrification device is used to perform desulfurization and denitrification treatment on the flue gas generated by the iron ore preheating unit after dust removal treatment to ensure that the discharged flue gas meets the emission standards.

[0016] Optionally, the primary treatment module further includes a first ash conveying device connected to the first dust removal device, and is used to receive and convey the dust captured in the first dust removal device to the hot ore storage bin; and / or,

[0017] The tertiary treatment module further includes a second ash conveying device connected to the second dust removal device, and is used to receive and convey the dust captured in the second dust removal device to the hot ore storage bin.

[0018] Optionally, the system further includes:

[0019] A coke oven gas unit, connected to the hydrogen production module, for providing hydrogen production raw materials; and / or,

[0020] The coke oven gas unit is connected to the drying and preheating unit, and is used to provide an energy source for the iron ore preheating unit.

[0021] Optionally, the exhaust ports of the first circulating fluidized bed and the second circulating fluidized bed are both connected to the heat exchanger.

[0022] In a second aspect, an embodiment of the present application provides a hydrogen-based pre-reduction method for iron ore powder in smelting reduction ironmaking, which is implemented by using the hydrogen-based pre-reduction system for iron ore powder in smelting reduction ironmaking described in the first aspect, and includes the following steps:

[0023] Obtain hot ore with a first preset temperature;

[0024] Obtain hydrogen with a second preset temperature;

[0025] Use the hydrogen as a reducing agent to perform a first pre-reduction reaction and a second pre-reduction reaction on the hot ore to obtain pre-reduced hot ore;

[0026] Perform smelting reduction ironmaking on the pre-reduced hot ore to obtain molten iron.

[0027] Optionally, the first preset temperature is 600°C to 700°C; and / or,

[0028] the second preset temperature is 600°C to 800°C.

[0029] Optionally, the time of the first pre-reduction reaction is 25 min to 35 min; and / or, the time of the second pre-reduction reaction is 35 min to 45 min.

[0030] Optionally, the method further includes: using the flue gas generated by the smelting reduction ironmaking reaction as the heat source for the hot ore and hydrogen.

[0031] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0032] The embodiments of the present application provide a hydrogen-based pre-reduction system and method for smelting reduction of iron ore powder, including: a drying and preheating unit for heating the iron ore to obtain hot ore with a first set temperature; a hydrogen preparation and temperature adjustment unit including a hydrogen production module and a heat exchanger for recovering waste heat from flue gas, for preparing and heating hydrogen to obtain hydrogen with a second set temperature; a multi-stage fluidized bed pre-reduction unit adopting a structure of a first circulating fluidized bed and a second circulating fluidized bed connected in series, for receiving the hot ore with the first set temperature and the hydrogen with the second set temperature to perform two-stage reduction reactions to obtain pre-reduced hot ore; fast reaction speed, reducing some iron oxides in the iron ore to metallic iron or low-valent iron oxides, providing high-quality raw materials for the subsequent smelting reduction final smelting unit; a smelting reduction final smelting unit including a smelting reduction furnace and a hydrogen-rich fuel injection system, for hot charging the pre-reduced hot ore into the smelting reduction furnace for final reduction reaction to produce high-quality molten iron; an energy recycling system including a flue gas three-stage treatment module connected in sequence, for recovering the flue gas generated during the smelting reduction ironmaking process, and using the flue gas as the heat source for hydrogen and hot ore through a heat exchanger, realizing the recycling of flue gas, reducing energy waste, and reducing the overall carbon emission of the system.

[0033] The technical solutions provided in the present application are energy-efficient, low-carbon and environmentally friendly, can improve production efficiency while realizing continuous production, reduce production costs, and conform to the concept of green smelting. Brief Description of the Drawings

[0034] The drawings herein are incorporated into and constitute a part of this specification, showing embodiments in accordance with the present application, and are used together with the specification to explain the principles of the present application.

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a schematic diagram of a hydrogen-based pre-reduction system for smelting iron ore powder by smelting reduction according to some embodiments of the present application;

[0037] In the figure: 1 is a drying and preheating unit, 2-1 is a first dust removal device, 2-2 is a second dust removal device, 3 is a desulfurization and denitration device, 4-1 is a first ash conveying device, 4-2 is a second ash conveying device, 5-1 is a first circulating fluidized bed, 5-2 is a second circulating fluidized bed, 6 is a hot ore storage bin, 7 is a hot ore injection device, 8 is a smelting reduction furnace, 9 is a hydrogen production device, and 10 is a heat exchanger.

[0038] Figure 2 It is a flow chart of a hydrogen-based pre-reduction method for smelting iron ore powder by smelting reduction according to some embodiments of the present application. Detailed Embodiments

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0040] The embodiments of the present application may be presented in a range form. This description is intended to simplify the expression and does not strictly limit the range. Therefore, the described range should be regarded as having covered all sub-ranges and specific values. For example, it should be considered that the description of the range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0041] In this text, terms such as "comprising" mean "including but not limited to". Relative terms such as "first" and "second" are only used to distinguish different entities or operations, and do not indicate an actual order or association between them. "And / or" is used to describe three possible relationships of associated objects: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. "At least one" means one or more, "a plurality" means two or more; "at least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces); for example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or plural respectively. "Parts representation method" such as parts by weight, parts by mass, etc. represents the proportional relationship between each component. In the proportional relationships involved in this text, when describing the proportional relationship, the parameters correspond to the antecedent of the proportion formula in the mentioned order, while the proportional numbers correspond to the consequent of the proportion formula. For example, the mass ratio of substance A, substance B, and substance C is 1:2:3, which means that in the described order, the mass of substance A corresponds to proportion 1, the mass of substance B corresponds to proportion 2, and the mass of substance C corresponds to proportion 3.

[0042] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in this text can be obtained through market purchase or can be prepared by existing methods.

[0043] Figure 1 It is a schematic diagram of a hydrogen-based pre-reduction system for smelting iron ore powder by smelting reduction according to some embodiments of this application;

[0044] As Figure 1 shown, the embodiments of this application provide a hydrogen-based pre-reduction system for smelting iron ore powder by smelting reduction, including:

[0045] A drying and preheating unit, which is used to heat up the iron ore, remove moisture and increase the temperature of the iron ore to obtain hot ore with a first set temperature; this unit provides dry and preheated hot ore raw materials for the subsequent multi-stage fluidized bed pre-reduction unit, reducing the energy consumption of the pre-reduction unit. At the same time, the heat source of this unit is the waste heat of the flue gas recovered by the flue gas circulation treatment unit, which can achieve efficient utilization of energy.

[0046] The multi-stage fluidized bed pre-reduction unit adopts the structure of a first circulating fluidized bed and a second circulating fluidized bed connected in series, and is connected to the drying and preheating unit. It is used to receive the hot ore with a first set temperature and the hydrogen with a second set temperature for two-stage reduction reaction, reducing part of the iron oxides in the iron ore to metallic iron or low-valent iron oxides, obtaining pre-reduced hot ore, and providing high-quality raw materials for the subsequent smelting reduction final smelting unit. The reduction reaction time of the multi-stage fluidized bed pre-reduction unit is short and the efficiency is high; there is no carbon emission during the reaction process.

[0047] The smelting reduction final smelting unit includes a smelting reduction furnace and a hydrogen-rich fuel injection system, and is used to hot-charge the pre-reduced hot ore into the smelting reduction furnace for final reduction reaction; high-quality molten iron is produced; this unit directly uses the pre-reduced hot ore to reduce the energy consumption in the smelting reduction final smelting stage.

[0048] The energy recycling system includes a three-stage flue gas treatment module connected in sequence, where,

[0049] The first-stage treatment module is connected to the flue gas discharge port of the smelting reduction furnace, and the high-temperature flue gas in the smelting reduction furnace is passed through the first-stage treatment and then into the heat exchanger;

[0050] The second-stage treatment module is connected to the flue gas outlet of the heat exchanger, and conveys the flue gas cooled down in the heat exchanger to the air inlet of the drying and preheating unit;

[0051] The third-stage treatment module is connected to the exhaust port of the drying and preheating unit, and purifies the flue gas at the exhaust port to meet the emission standards.

[0052] The energy recycling system is used to recover the flue gas generated during the molten final reduction ironmaking process, and use the flue gas as the heat source for the drying and preheating unit and hydrogen through the heat exchanger, realizing the recycling of the flue gas, reducing energy waste; reducing the overall carbon emission of the system, conforming to the concept of green smelting, improving the energy utilization efficiency of the system, and reducing the dependence on external energy.

[0053] In the above embodiment, the prepared hydrogen is used as a reducing agent to participate in the pre-reduction reaction, effectively reducing the use of anthracite, ensuring no carbon emission during the reduction process, and thus reducing the carbon emission. Using the circulating fluidized bed as the equipment for the pre-reduction reaction, the solid particles are in a highly turbulent state in the gas flow during the reaction process, which increases the gas-solid contact area and significantly improves the heat transfer and mass transfer efficiency. Therefore, the reaction time is shortened and the efficiency is improved; at the same time, the unreacted particles can be returned to the reactor interior through the separator and the return material system, further improving the reaction efficiency and reducing the raw material consumption.

[0054] In the above embodiment, the pre-reduction unit in the system uses hydrogen gas with a second set temperature as a reducing agent to perform a two-stage reduction process on hot ore with a first set temperature in the first circulating fluidized bed and the second circulating fluidized bed. This process has a fast reaction speed, high energy utilization rate, and no carbon emissions. An energy recycling system is used to realize the recycling of flue gas, significantly reducing energy consumption and at the same time reducing waste gas emissions, further realizing low-carbon production. It can be used as an alternative to the traditional blast furnace ironmaking process, promoting the development of the steel industry towards low-carbon and intelligent directions.

[0055] As an optional implementation method, the drying and preheating unit is composed of a rotary kiln. Its kiln head is connected to the secondary treatment module of the energy recycling system, and its kiln tail is connected to the iron ore feed inlet. The iron ore raw material enters the rotary kiln from the feed inlet at the kiln tail and completes the drying and preheating process of the iron ore raw material in a countercurrent manner under the heating of the flue gas generated by the smelting reduction furnace.

[0056] In the above embodiment, the iron ore is heated in a countercurrent manner in the rotary kiln, and the iron ore is in full contact with the flue gas, resulting in higher utilization rate of the flue gas heat.

[0057] As an optional embodiment, the hydrogen-rich fuel injection system includes a hot ore storage bin and a hot ore injection device. The hot ore storage bin is connected to the multi-stage fluidized bed pre-reduction unit for receiving and storing pre-reduced hot ore; the hot ore injection device is used to load the pre-reduced hot ore in the hot ore storage bin into the smelting reduction furnace.

[0058] In the above embodiment, the hot ore storage bin can be used as a buffer device for hot ore. It has a large designed capacity, centrally stores the pre-reduced hot ore after pre-reduction, ensures continuous feeding of the smelting reduction furnace, and can meet the continuous production requirements of the smelting reduction furnace; at the same time, it has a heat preservation function to prevent the rapid drop of the hot ore temperature and reduce heat loss. The hot ore injection device can control the injection speed and quantity of hot ore to ensure the stable operation of the smelting reduction furnace; the smelting reduction furnace is used to receive the hot ore sent by the hot ore injection device and perform the smelting reduction ironmaking process, further reducing the iron oxides in the pre-reduced hot ore to metallic iron and melting them into molten iron. In summary, through the coordinated work of the hot ore storage bin, the hot ore injection device and the smelting reduction furnace, the molten reduction final smelting unit realizes the efficient reduction and smelting of iron ore, has the advantages of continuous production, high-efficiency reduction and low-carbon environmental protection, and is an important part of modern steel smelting technology.

[0059] As an optional embodiment, the primary treatment module includes a first dust removal device connected in series. The first dust removal device is used to remove the dust in the high-temperature flue gas from the smelting reduction furnace and input the dust-removed flue gas into the heat exchanger.

[0060] In the above embodiments, since the flue gas generated in the smelting reduction furnace contains relatively high levels of dust, SO2, NO x , CO, CH4, and H2, the first dust removal device is required to capture the solid particulate matter in the flue gas through filtration or electrostatic dust removal technology to remove the dust in the flue gas generated by the final smelting unit of smelting reduction. This not only reduces the dust content in the flue gas, making the dust content

[0061] ≤10mg / Nm 3 , and avoids damage to subsequent equipment by dust. The dust-removed flue gas can be heat-exchanged with the hydrogen produced by the hydrogen production device in a heat exchanger and then transmitted to the drying and preheating unit as fuel through a secondary treatment module.

[0062] As an alternative embodiment, the tertiary treatment module includes a second dust removal device and a desulfurization and denitrification device connected in series. The second dust removal device is connected to the exhaust port of the drying and preheating unit and is used to remove the dust in the flue gas generated by the drying and preheating unit; the desulfurization and denitrification device is used to perform desulfurization and denitrification treatment on the flue gas generated by the iron ore preheating unit after dust removal treatment to ensure that the discharged flue gas meets the emission standards.

[0063] In the above embodiments, the flue gas generated in the drying and preheating unit includes dust, sulfur dioxide, nitrogen oxides, etc. The second dust removal device can capture the solid particles in the flue gas through filtration or electrostatic dust removal technology, while reducing the carbon emissions in the flue gas. The desulfurization and denitrification device can purify sulfur dioxide and nitrogen oxides in the flue gas through desulfurization and denitrification to ensure that the discharged flue gas meets the emission standards.

[0064] As an alternative embodiment, the primary treatment module further includes a first ash conveying device connected to the first dust removal device and used to receive and convey the dust captured in the first dust removal device to the hot ore storage bin.

[0065] As an alternative embodiment, the tertiary treatment module further includes a second ash conveying device connected to the second dust removal device and used to receive and convey the dust captured in the second dust removal device to the hot ore storage bin.

[0066] In the above embodiments, the first ash conveying device and the second ash conveying device respectively use pneumatic conveying or mechanical conveying methods to convey the dust captured by the first dust removal device and the second dust removal device to the hot ore storage bin to ensure the efficient transportation of dust; not only recycle the useful components in the dust as raw materials for smelting reduction ironmaking, but also, due to the good sealing of the ash conveying device, avoid secondary pollution caused by dust leakage.

[0067] In the above-described embodiment, the dust captured by the first dust removal device and the second dust removal device needs to be subjected to component detection. When its components meet the requirements of iron ore raw materials, such as an iron content ≥ 90%, it can be recycled to the hot ore storage bin by means of an ash conveying device to prevent impurities from contaminating the pre-reduced ore.

[0068] In the above-described embodiment, the entire energy recycling system recovers the waste heat of the flue gas, which is used to preheat the iron ore, reduce the energy consumption of the drying and preheating unit, and improve the overall energy utilization efficiency of the system. Through dust removal, desulfurization, denitrification, and waste heat recovery, efficient treatment of the flue gas and recycling of energy are achieved. In addition, this unit not only achieves efficient removal of dust and sulfides, but also improves the resource utilization efficiency through dust reuse, embodying the concepts of green metallurgy and sustainable development.

[0069] In summary, the energy recycling system can not only meet strict environmental protection requirements, but also significantly improve the energy utilization efficiency of the system, and is an important technical support for green metallurgy and sustainable development.

[0070] As an alternative embodiment, the system further includes:

[0071] A coke oven gas unit, connected to the hydrogen production module, for providing hydrogen production raw materials. Using coke oven gas as the hydrogen production raw material to produce hydrogen as a reducing agent in the pre-reduction process.

[0072] In the above-described embodiment, coke oven gas is a by-product generated during the coking process, including hydrogen, methane, carbon monoxide, and a small amount of other gases. Using the hydrogen in coke oven gas as the hydrogen production raw material can realize the recycling of coke oven gas, which is an efficient and low-carbon green metallurgy technology. This process not only realizes the high-value utilization of coke oven gas, but also significantly reduces the carbon emissions in the pre-reduction process, meeting the goals of sustainable development in the iron and steel industry. At the same time, the other components besides hydrogen production are flammable and can be directly burned as the heat source for the iron ore preheating unit to meet the high-temperature requirements of the rotary kiln. The pollutants generated by combustion are less and the use cost is lower. It can also be used for other purposes or directly discharged after flue gas treatment.

[0073] As an alternative embodiment, the coke oven gas unit is connected with a purification device, and the purification device is used to purify the impurities and / or other gases in the coke oven gas, and then use the purified coke oven gas as the hydrogen production raw material for the hydrogen production device.

[0074] As an alternative embodiment, the coke oven gas unit is connected to the drying and preheating unit, for providing an energy source to the iron ore drying and preheating unit.

[0075] In the above embodiments, since the coke oven gas contains hydrogen, methane, carbon monoxide and a small amount of other gases, it is flammable and can be directly burned as the heat source for the iron ore preheating unit to meet the high temperature requirements of the rotary kiln. The pollutants generated by combustion are less and the use cost is lower.

[0076] As an alternative embodiment, the flue gas at the exhaust ports of the first circulating fluidized bed and the second circulating fluidized bed has a relatively high H2 concentration, about 35% - 45%. Therefore, the exhaust ports of the first circulating fluidized bed and the second circulating fluidized bed are both connected to the heat exchanger and enter the heat exchanger together with the hydrogen generated in the hydrogen production module for heat exchange. After reaching the second set temperature, it is transmitted to the first circulating fluidized bed and the second circulating fluidized bed again to further realize the green circular economy.

[0077] In a second aspect, an embodiment of the present application provides a hydrogen-based pre-reduction method for iron ore powder in smelting reduction ironmaking, which is implemented by using the hydrogen-based pre-reduction system for iron ore powder in smelting reduction ironmaking described in the first aspect, and includes the following steps:

[0078] S1, obtaining hot ore with a first preset temperature;

[0079] S2, obtaining hydrogen with a second preset temperature;

[0080] The purposes of steps S1 and S2 are to provide reaction raw materials for the subsequent pre-reduction reaction respectively;

[0081] S3, using the hydrogen as a reducing agent to carry out a first pre-reduction reaction and a second pre-reduction reaction on the hot ore to obtain pre-reduced hot ore;

[0082] In step S3, using the hydrogen as a reducing agent to carry out a staged pre-reduction reaction on the hot ore has a higher reduction efficiency.

[0083] S4, carrying out smelting reduction ironmaking on the pre-reduced hot ore to obtain molten iron.

[0084] In step S4, the final reduction and smelting of the iron ore are completed to produce high-quality molten iron.

[0085] In the above embodiments, to obtain hot ore with a first preset temperature, devices such as rotary kilns or fluidized beds can be used to heat iron ore raw materials to the first preset temperature, providing thermodynamic conditions for subsequent pre-reduction reactions; to obtain hydrogen with a second preset temperature, a coke oven gas hydrogen production device or other hydrogen production processes can be used to obtain high-purity hydrogen, and then the prepared hydrogen can be heated to the second set temperature through heating devices including but not limited to heat exchangers and electric heaters, serving as a reducing agent for pre-reduction reactions to ensure the efficient progress of pre-reduction reactions. In the pre-reduction reactions, a circulating fluidized bed is respectively used for the first pre-reduction reaction and the second pre-reduction reaction. After the first pre-reduction, the reduction degree of the hot ore can reach 35%; after the second pre-reduction reaction, the reduction degree of the hot ore can reach 60%, and the carbon dioxide emission during the reaction process is 0.

[0086] As an alternative embodiment, the first preset temperature is 600°C to 700°C; the second preset temperature is 600°C to 800°C.

[0087] In the above embodiments, the reason for controlling the first preset temperature to be 600°C to 700°C is that the reducing agent used in the present invention is hydrogen. According to the physical and chemical properties of hydrogen, the optimal temperature range for reduction is 650°C to 750°C. If the parameters in the present invention are exceeded, the effect of iron ore pre-reduction is not ideal, the pre-reduction degree is relatively low, and the reduction purpose cannot be achieved. Exemplarily, the first preset temperature can be 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C or 700°C.

[0088] The reason for controlling the second preset temperature to be 600°C to 800°C is that after mixing and heat exchange with hydrogen within this temperature range, in the circulating fluidized bed, the heat exchange between iron ore and hydrogen can reach the optimal temperature range for reduction of 650°C to 750°C. Exemplarily, the second preset temperature can be 600°C, 620°C, 640°C, 650°C, 660°C, 680°C, 700°C, 720°C, 740°C, 750°C, 760°C, 780°C or 800°C.

[0089] As an alternative embodiment, the time of the first pre-reduction reaction is 25 min to 35 min; and / or, the time of the second pre-reduction reaction is 35 min to 45 min.

[0090] In the above-described embodiment, due to the use of a circulating fluidized bed, the efficiency of the first pre-reduction reaction is high and the time is short. Therefore, the time for the first pre-reduction only needs to be 25 min to 35 min. Exemplarily, the time for the first pre-reduction reaction can be 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min or 35 min. The reason for the time of the second pre-reduction reaction being 35 min to 45 min is that there is less raw material to be reduced during the second pre-reduction reaction. Therefore, the reaction rate requires a longer time compared to the first pre-reduction. Exemplarily, the time for the first pre-reduction reaction can be 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min, 43 min, 44 min or 45 min.

[0091] As an alternative embodiment, the gas velocity of the first circulating fluidized bed is 1.5 m / s to 2.5 m / s, and the gas velocity of the second circulating fluidized bed is 2 m / s to 3.5 m / s.

[0092] In the above-described embodiment, exemparily, the gas velocity of the first circulating fluidized bed can be 1.5 m / s, 1.8 m / s, 2.0 m / s, 2.2 m / s or 2.5 m / s. The gas velocity of the second circulating fluidized bed can be 2 m / s, 2.2 m / s, 2.5 m / s, 3.0 m / s, 3.3 m / s or 3.5 m / s.

[0093] As an alternative embodiment, the method further includes: using the flue gas generated by the smelting reduction ironmaking reaction as the heat source for the hot ore and hydrogen.

[0094] In the above-described embodiment, using the flue gas generated by the smelting reduction ironmaking reaction as the heat source for the hot ore and hydrogen can further reduce carbon emissions.

[0095] Next, specific embodiments are used to further illustrate the present application. For the experimental methods without specific conditions noted in the following embodiments, they are usually measured according to national standards / industry standards; if there are no corresponding national standards / industry standards, they are carried out according to general international standards, conventional conditions or according to the conditions recommended by the manufacturer.

[0096] Example 1

[0097] This example provides a hydrogen-based pre-reduction system for smelting reduction of iron ore powder, as Figure 1 shown, including a drying and preheating unit for heating the iron ore to obtain hot ore with a first set temperature;

[0098] The hydrogen production and temperature regulation unit includes a hydrogen production module and a heat exchanger for recovering waste heat from flue gas, which is used to produce and heat hydrogen to obtain hydrogen with a second set temperature;

[0099] The multi-stage fluidized bed pre-reduction unit adopts a structure of a first circulating fluidized bed and a second circulating fluidized bed connected in series, and is used to receive the hot ore with a first set temperature and the hydrogen with a second set temperature for two-stage reduction reaction to obtain pre-reduced hot ore;

[0100] The smelting reduction final smelting unit includes a smelting reduction furnace, a hot ore storage bin and a hot ore injection device, which is used to thermally store the pre-reduced hot ore and use the injection device to load it into the smelting reduction furnace for final reduction reaction;

[0101] The energy circulation system includes a three-stage flue gas treatment module connected in sequence, where,

[0102] The first-stage treatment module includes a first dust removal device and a first ash conveying device. The first dust removal device is connected to the flue gas discharge port of the smelting reduction furnace and is used to remove dust from the high-temperature flue gas in the smelting reduction furnace and then pass it into the heat exchanger for heat exchange with hydrogen; the first ash conveying device inputs the dust captured by the first dust removal device into the hot ore storage bin for recycling;

[0103] The second-stage treatment module is connected to the flue gas outlet of the heat exchanger and conveys the flue gas cooled in the heat exchanger to the air inlet of the drying and preheating unit;

[0104] The third-stage treatment module includes a second dust removal device, a second ash conveying device and a desulfurization and denitration device. The second dust removal device is connected to the exhaust port of the drying and preheating unit, removes dust from the flue gas at the exhaust port and then enters the desulfurization and denitration device, and after being subjected to desulfurization and denitration treatment by the desulfurization and denitration device, it is discharged to the atmosphere after reaching the emission standard.

[0105] The coke oven gas unit is respectively connected to the hydrogen production module and the drying and preheating unit. On the one hand, it is used to provide hydrogen production raw materials for the hydrogen production module, and on the other hand, it is used to provide an energy source for the iron ore preheating unit.

[0106] In this embodiment, the exhaust ports of the first circulating fluidized bed and the second circulating fluidized bed are both connected to the heat exchanger. There is still 35% hydrogen in the gas discharged after pre-reduction treatment, which can enter the heat exchanger for heat exchange with the hydrogen generated in the hydrogen production module, and after reaching the second set temperature, it is transmitted to the first circulating fluidized bed and the second circulating fluidized bed again.

[0107] Example 2

[0108] This embodiment provides a hydrogen-based pre-reduction method for iron ore powder in smelting reduction ironmaking, which is realized by using the hydrogen-based pre-reduction system for iron ore powder in smelting reduction ironmaking described in Embodiment 1, and includes the following steps:

[0109] S1. The particle size of the iron ore is selected to be ≤6 mm. The rotary kiln process is adopted in a countercurrent form, with feeding at the kiln tail and heating by burning the flue gas of the smelting reduction furnace at the kiln head, and coke oven gas is used for ignition.

[0110] The iron ore is heated in the drying and preheating unit to obtain hot ore at 600°C - 700°C.

[0111] S2. Using coke oven gas as raw material, hydrogen is prepared by the hydrogen production module, and the prepared hydrogen is heat-exchanged with the flue gas of the smelting reduction furnace through a heat exchanger. The initial temperature of the flue gas of the smelting reduction furnace reaches 1000°C, and hydrogen at 600°C - 800°C is obtained after heat exchange.

[0112] S3. Using the hydrogen as a reducing agent, the first pre-reduction reaction is carried out on the hot ore in the first circulating fluidized bed; the reaction time is 30 min.

[0113] The reactants after the first pre-reaction are subjected to a second pre-reduction reaction in the second circulating fluidized bed, and the reaction time is 35 min to obtain pre-reduced hot ore.

[0114] S4. The pre-reduced hot ore is stored in the hot ore storage bin, and the hot ore is sprayed into the smelting reduction furnace through the hot ore injection device for smelting reduction ironmaking to obtain molten iron.

[0115] S5. The flue gas generated in the smelting reduction furnace is treated by the primary treatment module in the energy recycling system and then introduced into the heat exchanger to heat up the hydrogen to obtain hydrogen with a second preset temperature. The cooled flue gas enters the drying and preheating unit through the secondary treatment module to continue heating the iron ore to obtain hot ore with a first preset temperature, and it is recycled.

[0116] In this embodiment, based on the industrial smelting reduction furnace gas composition, the calculated CO2 emission per ton of ore is 94.03 kg.

[0117] To sum up, the hydrogen-based pre-reduction system and method for iron ore powder in smelting reduction ironmaking provided in different embodiments of this application have at least the following advantages:

[0118] 1) The iron ore is pre-reduced using the circulating fluidized bed process. The dried and pre-heated material (temperature 600°C - 700°C) enters the first circulating fluidized bed and undergoes primary reduction after heat exchange with hydrogen produced by a high-temperature coke oven gas hydrogen production device. The reduction time is approximately 30 minutes, and the reduction degree of the iron ore can reach 35%. The reduced iron ore then enters the second circulating fluidized bed and undergoes ultimate reduction using hydrogen produced by the high-temperature coke oven gas hydrogen production device. The reduction time is approximately 40 minutes, and the reduction degree of the iron ore can reach 60%. There is no carbon inflow during the reduction process of this technology, and the CO2 emissions are zero.

[0119] 2) The CO2 emissions per ton of ore in the entire process of iron ore drying and pre-reduction by this technology are 94.03 kg, which can be reduced by 77.79% compared to the traditional coal-based process.

[0120] 3) The flue gas from the smelting reduction furnace contains relatively high amounts of dust, SO2, NO x , CO, CH4, and H2, and the temperature is relatively high, about 1050°C. After passing through the second dust removal device, the dust content in the flue gas is ≤10 mg / Nm 3 . After heat exchange with the hydrogen produced by the coke oven gas hydrogen production device through a heat exchanger, it not only heats the hydrogen, but also the flue gas serves as the fuel for the rotary kiln, eliminating the need for additional fuel heating and achieving the purpose of energy conservation.

[0121] 4) The coke oven gas can be divided into two paths. One path is sent to the kiln head of the rotary kiln for ignition, and the other path enters the coke oven gas hydrogen production device to produce hydrogen. The produced hydrogen enters the heat exchanger and is heated to a temperature of 600°C - 800°C to serve as the reducing agent for the first and second circulating fluidized beds.

[0122] 5) The H2 concentration in the flue gas at the outlets of the first and second circulating fluidized beds is approximately 35% - 45%. After mixing with the hydrogen produced by the coke oven gas hydrogen production device, they enter the heat exchanger together and are heated to a temperature of 600°C - 800°C to serve as the reducing agent for the first and second circulating fluidized beds and are recycled, which conforms to the green circular economy model.

[0123] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but rather will conform to the broadest scope consistent with the principles and novel features claimed in the present application.

Claims

1. A hydrogen-based pre-reduction system for smelting iron ore powder by smelting reduction, characterized in that, Comprising: A drying and preheating unit for heating the iron ore to obtain hot ore with a first set temperature; A hydrogen production and temperature regulation unit, including a hydrogen production module and a heat exchanger for recovering waste heat from flue gas, for producing and heating hydrogen to obtain hydrogen with a second set temperature; A multi-stage fluidized bed pre-reduction unit, adopting a structure of a first circulating fluidized bed and a second circulating fluidized bed in series, for receiving the hot ore with the first set temperature and the hydrogen with the second set temperature to carry out two-stage reduction reactions to obtain pre-reduced hot ore; A smelting reduction final smelting unit, including a smelting reduction furnace and a hydrogen-rich fuel injection system, for hot charging the pre-reduced hot ore into the smelting reduction furnace for final reduction reactions; An energy recycling system, including a flue gas three-stage treatment module connected in sequence, wherein, The first-stage treatment module is connected to the flue gas discharge port of the smelting reduction furnace, and feeds the high-temperature flue gas in the smelting reduction furnace into the heat exchanger; The second-stage treatment module is connected to the flue gas outlet of the heat exchanger, and conveys the cooled flue gas in the heat exchanger to the air inlet of the drying and preheating unit; The third-stage treatment module is connected to the exhaust port of the drying and preheating unit, and purifies the flue gas at the exhaust port to meet the emission standards.

2. The hydrogen-based pre-reduction system for reducing iron ore powder according to claim 1, wherein, The hydrogen-rich fuel injection system includes a hot ore storage bin and a hot ore injection device, the hot ore storage bin is connected to the multi-stage fluidized bed pre-reduction unit, for receiving and storing pre-reduced hot ore; The hot ore injection device is used for charging the pre-reduced hot ore in the hot ore storage bin into the smelting reduction furnace.

3. The hydrogen-based pre-reduction system for reducing iron ore powder according to claim 1, characterized in that, The first-stage treatment module includes a first dust removal device for removing dust in the high-temperature flue gas in the smelting reduction furnace; and / or, The third-stage treatment module includes a second dust removal device and a desulfurization and denitrification device connected in series, the second dust removal device is connected to the exhaust port of the drying and preheating unit, for removing dust in the flue gas generated by the drying and preheating unit; the desulfurization and denitrification device is used for carrying out desulfurization and denitrification treatment on the flue gas generated by the iron ore preheating unit after dust removal treatment to ensure that the discharged flue gas meets the emission standards.

4. The hydrogen-based pre-reduction system for reducing iron ore powder according to claim 3, characterized in that, The first-stage treatment module further includes a first ash conveying device connected to the first dust removal device, for receiving and conveying the dust captured in the first dust removal device to the hot ore storage bin; and / or, The third-stage treatment module further includes a second ash conveying device connected to the second dust removal device, for receiving and conveying the dust captured in the second dust removal device to the hot ore storage bin.

5. The hydrogen-based pre-reduction system for smelting iron ore powder by smelting reduction according to claim 1, wherein, The system further includes: A coke oven gas unit connected to the hydrogen production module, for providing hydrogen production raw materials; and / or, The coke oven gas unit is connected to the drying and preheating unit, for providing an energy source to the iron ore preheating unit.

6. The hydrogen-based pre-reduction system for smelting iron ore powder by smelting reduction according to claim 1, characterized in that The exhaust ports of the first circulating fluidized bed and the second circulating fluidized bed are both connected to the heat exchanger.

7. A hydrogen-based pre-reduction method for iron ore powder in smelting reduction ironmaking, which is realized by using the system described in any one of claims 1 to 6, characterized in that, Including the following steps: Obtaining hot ore with a first preset temperature; Obtaining hydrogen with a second preset temperature; Using the hydrogen as a reducing agent to carry out a first pre-reduction reaction and a second pre-reduction reaction on the hot ore to obtain pre-reduced hot ore; Carrying out smelting reduction ironmaking on the pre-reduced hot ore to obtain molten iron.

8. The method according to claim 7, wherein The first preset temperature is 600°C to 700°C; and / or, The second preset temperature is 600°C to 800°C.

9. The method according to claim 7, wherein The time of the first pre-reduction reaction is 25 min to 35 min; and / or, the time of the second pre-reduction reaction is 35 min to 45 min.

10. The method according to claim 7, characterized in that, The method further includes: using the flue gas generated by the smelting reduction ironmaking reaction as the heat source for the hot ore and the hydrogen.

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