Gas-based shaft furnace system and method based on reducing gas co-production and recycling

Abstract

The application discloses a gas-based shaft furnace system and method based on reduction gas cooperation preparation and recycling, and the system comprises a gasification furnace (1), a dust remover (2), an ash removal tank (3), a dust removal and desulfurization furnace (4), a heating furnace (5), a shaft furnace (6), a waste boiler (7), a reduction gas preheater (8), a circulating gas washing tower (9), a shift device (10), a compressor (11) and a decarburization device (12). In the application, high-temperature reduction gas generated by coal gasification is directly used for a reduction reaction of the shaft furnace after dust removal and desulfurization under high-temperature conditions, tail gas of the shaft furnace is recycled after waste heat recovery, component adjustment and decarburization treatment, a closed-circuit operation system is formed, comprehensive utilization of sensible heat and chemical energy of the reduction gas is realized, deep cooling and repeated heating links are reduced, and the overall thermal efficiency of the system is improved and energy consumption is reduced.

Description

Technical Field

[0001] This invention relates to the field of gas-based vertical shaft furnace ironmaking technology, and in particular to a gas-based vertical shaft furnace system and method based on the synergistic preparation and recycling of reducing gas. Background Technology

[0002] As a traditional high-energy-consuming and high-carbon-emission industry, the steel industry is facing the need for technological transformation to deeply decarbonize.

[0003] Traditional blast furnace ironmaking uses coke and iron ore as main raw materials. The process is lengthy, generates high levels of pollutants, and is highly dependent on high-quality metallurgical coke, resulting in persistently high resource consumption and carbon emissions. Gas-based shaft furnace ironmaking processes (such as MIDREX and HYL-Energiron) use reducing gas (mainly composed of hydrogen and CO) instead of solid coke for ironmaking, offering advantages such as lower carbon emissions, greater process continuity, and higher automation. They are gradually becoming an important route towards green metallurgy. The principle is mainly based on the reduction reaction between a gaseous reducing agent and iron oxide ore in the shaft furnace to produce metallic iron.

[0004] However, the selection, purification, and heating processes of reducing gas sources for gas-based vertical shaft furnaces are significantly constrained by domestic and international resource endowments and engineering conditions. Existing gas-based vertical shaft furnace processes still face the following technical challenges: ① Reliance on a single reducing gas source: Considering the differences in resources between domestic and international markets, foreign gas-based vertical shaft furnaces have long relied on natural gas methane reforming as their core gas source, achieving stable operation by leveraging abundant gas resources. my country, however, has limited natural gas reserves and high costs, making it difficult to replicate this approach. The industry has turned to coke oven gas, a byproduct of the steel co-production system, as an alternative reducing gas source. However, coke oven gas production and composition are limited, and its large-scale application is still not suitable for my country's basic national conditions of "abundant coal, scarce oil, and limited gas." Therefore, coal-to-gas has become the mainstream gas source direction that adapts to my country's resource structure and ensures large-scale continuous production of gas-based vertical shaft furnaces.

[0005] ② Coke oven gas and conventional coal gas have common shortcomings in composition. The sulfur content of the raw gas is relatively high, which can easily cause corrosion of vertical furnace equipment, catalyst poisoning and product contamination. A complete purification and pretreatment process must be provided. The industry generally adopts a combination of water washing, cooling, dust removal and deep desulfurization to achieve clean and high-quality raw gas and meet the stringent requirements of reduction process for gas purity.

[0006] ③ The clean reducing gas after deep desulfurization cannot directly meet the temperature requirements of high-temperature reduction in the vertical furnace due to the significant temperature drop during the pretreatment process. It must be heated again to the process set temperature through a special heating device. This step significantly increases the system heat loss and overall energy consumption, becoming a key technical pain point that urgently needs to be optimized in the current gas-based vertical furnace process.

[0007] Therefore, considering my country's resource situation of "abundant coal, scarce oil, and limited gas," and the existing technological limitations of gas-based vertical shaft furnaces, the large-scale and low-carbon development of gas-based vertical shaft furnaces in my country must establish a core gas source route based on coal-to-gas conversion. Simultaneously, addressing the issue of high sulfur content in coke oven gas and conventional coal-to-gas conversion, it is necessary to improve the combined pretreatment scheme of water washing, cooling, dust removal, and desulfurization to ensure the cleanliness of reducing gas and prevent damage to equipment and products. Addressing the bottleneck of increased energy consumption due to the need for reheating after desulfurization, there is an urgent need to develop a new low-carbon gas-based vertical shaft furnace ironmaking process adapted to these gas source conditions, capable of comprehensively solving the high energy consumption problems of raw material gas desulfurization purification and reheating. This process should optimize pretreatment and heating procedures, reduce system energy consumption, and improve the safety, stability, and environmental friendliness of process operation, providing technical support for deep decarbonization in the steel industry. Summary of the Invention

[0008] The purpose of this invention is to provide a gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas, so as to at least partially solve the above-mentioned problems of the prior art.

[0009] To achieve the above objectives, one aspect of the present invention provides a gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas, comprising a gasifier 1, a dust collector 2, an ash removal tank 3, a dust removal and desulfurization furnace 4, a heating furnace 5, a vertical shaft furnace 6, a waste heat boiler 7, a reducing gas preheater 8, a circulating gas scrubbing tower 9, a conversion device 10, a compressor 11, and a decarbonization device 12; wherein The feed inlet of gasifier 1 is connected to the raw coal inlet and the oxygen inlet respectively to generate high-temperature syngas. The syngas outlet at the top of gasifier 1 is directly connected to the inlet of dust collector 2. The top gas outlet of dust collector 2 is connected to dust removal and desulfurization furnace 4, and the bottom is connected to ash removal tank 3; The dust removal and desulfurization furnace 4 is used to remove dust and sulfide impurities from the syngas under high temperature conditions, and is equipped with a desulfurizing agent inlet at the top; the top gas outlet pipe of the dust removal and desulfurization furnace 4 is connected to the gas outlet of the heating furnace 5 and the gas inlet of the vertical furnace 6. The top of the vertical shaft furnace 6 is equipped with an iron ore pellet inlet, the bottom or side is equipped with a gas inlet, the bottom is equipped with a DRI exhaust outlet, and the top is also equipped with a tail gas outlet directly connected to the waste boiler 7. The exhaust gas from the waste boiler 7, after waste heat recovery, is connected to the reducing gas preheater 8 via a pipeline. The reducing gas preheater 8 is connected to the waste boiler 7, the circulating gas scrubbing tower 9, the compressor 11, and the gasifier 1. It transmits the gas input from the waste boiler 7 to the circulating gas scrubbing tower 9 and uses the gas input from the waste boiler 7 to preheat the gas input from the compressor 11. The preheated gas is then input into the gasifier 1. The circulating gas scrubbing tower 9 is connected to the reducing gas preheater 8, the conversion device 10 and the decarbonization device 12. After scrubbing and removing dust from the gas received from the reducing gas preheater 8, one path is input into the conversion device 10 and the other path is input into the decarbonization device 12 as a non-conversion line. The conversion device 10 is connected to the decarbonization device 12 and / or the compressor 11, and is used to carry out a water-gas conversion reaction to adjust the ratio of CO to hydrogen. The decarbonization device 12 is connected to the compressor 11 and is used to input the decarbonized gas into the compressor 11. The gas outlet of the compression molding machine 11 is connected to the reducing gas preheater 8, the dust removal and desulfurization furnace 4, the heating furnace 5 and the vertical furnace 6, and outputs circulating gas.

[0010] Preferably, the system also includes a steam drum 13, which is connected to the waste boiler 7 and is used to generate steam.

[0011] Preferably, the top exhaust pipe of the dust removal and desulfurization furnace 4 is connected to the exhaust pipe of the heating furnace 5, and then connected to the vertical furnace 6.

[0012] Preferably, the top of the dust removal and desulfurization furnace 4 is also provided with a carbon dioxide inlet.

[0013] Preferably, the conversion device 10 is connected to the decarbonization device 12, and the gas after the water-gas conversion reaction is input into the decarbonization device 12.

[0014] Preferably, the decarbonization device 12 includes a circulating gas outlet, a carbon dioxide outlet, and a tail gas outlet. Carbon dioxide is discharged through the carbon dioxide outlet, a portion of the decarbonized gas is output to the compressor 11 through the circulating gas outlet, and another portion of the decarbonized gas is output downstream through the tail gas outlet.

[0015] Preferably, the system further includes a washing tower, which is connected to the ash removal tank 3, for washing the ash and slag output from the ash removal tank 3.

[0016] Another aspect of the present invention provides a gas-based vertical shaft furnace operation method based on the synergistic preparation and recycling of reducing gas, applicable to the systems provided in the above aspects and any embodiments thereof, the method comprising: Raw coal and oxygen are fed into the gasifier 1 through the feed inlet to undergo a gasification reaction, generating high-temperature syngas with CO and hydrogen as the main components. The generated high-temperature syngas is then output to the dust collector 2 through the top syngas outlet of the gasifier 1. The high-temperature syngas undergoes primary dust removal treatment through dust collector 2. The solid particles after dust removal and separation are discharged from the bottom of dust collector 2 into ash removal tank 3, and the syngas after dust removal treatment is output to dust removal and desulfurization furnace 4 through the gas outlet at the top of dust collector 2. High-temperature desulfurizing agent is added through the high-temperature desulfurizing agent dosing system built into the dust removal and desulfurization furnace 4, so that the syngas can complete the desulfurization reaction under high temperature conditions. The gas discharged from the heating furnace 5 is mixed with the syngas discharged from the dust removal and desulfurization furnace 4, and the temperature of the syngas is adjusted according to the operating temperature requirements of the vertical furnace 6. The iron ore pellets are reduced in the vertical furnace 6, and the generated reduced iron is discharged from the bottom and the high-temperature tail gas is discharged from the top. The waste heat of the high-temperature exhaust gas discharged from the vertical furnace 6 is recovered by the waste boiler 7. The exhaust gas after waste heat recovery enters the circulating gas scrubbing tower 9 through the reducing gas preheater 8 to complete the cooling and impurity removal. The circulating gas after being treated by the circulating gas scrubbing tower 9 is divided into two paths: one path first enters the shift converter 10 to carry out a water-gas shift reaction to adjust the ratio of CO to hydrogen, and then enters the decarbonization unit 12; the other path directly enters the decarbonization unit 12. After decarbonization treatment in the decarbonization device 12, the gas enters the compressor 11 and is then output as circulating gas to the dust removal and desulfurization furnace 4, the heating furnace 5, the vertical furnace 6, and the reducing gas preheater 8. The gas preheated by the reducing gas preheater 8 enters the gasifier 1.

[0017] Compared with the prior art, the present invention has at least the following advantages: The high-temperature reducing gas produced by coal gasification is directly used for the reduction reaction in the vertical shaft furnace after dust removal and desulfurization under high-temperature conditions. The tail gas of the vertical shaft furnace is recycled after waste heat recovery, composition adjustment and decarbonization treatment, forming a closed-loop operation system. This realizes the comprehensive utilization of the sensible heat and chemical energy of the reducing gas, reduces the deep cooling and repeated heating links, improves the overall thermal efficiency of the system and reduces energy consumption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas, provided in an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate to understand the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a product or device comprising a series of units is not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to such product or device.

[0021] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0022] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0023] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Example 1

[0025] One aspect of the present invention provides a gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas. Figure 1 A schematic diagram of the system structure is shown. For example... Figure 1As shown, the system includes a gasifier 1, a dust collector 2, an ash removal tank 3, a dust removal and desulfurization furnace 4, a heating furnace 5, a vertical furnace 6, a waste heat boiler 7, a reducing gas preheater 8, a circulating gas scrubbing tower 9, a conversion device 10, a compressor 11, and a decarbonization device 12. All devices in this system are connected sequentially through sealed high-temperature resistant pipelines, forming a continuously operating integrated system.

[0026] The feed inlet of gasifier 1 is connected to the raw coal inlet and the oxygen inlet respectively to generate high-temperature syngas. The syngas outlet at the top of gasifier 1 is directly connected to the inlet of dust collector 2.

[0027] The top gas outlet of dust collector 2 is connected to the dust removal and desulfurization furnace 4, and the bottom is connected to the ash removal tank 3. Dust collector 2 is used for primary dust removal treatment of crude syngas.

[0028] Ash removal tank 3 is used to collect the separated solid particles. Ash removal tank 3 can be connected to a washing tower to wash the ash and slag output from ash removal tank 3.

[0029] The dust removal and desulfurization furnace 4 is used to remove dust and sulfide impurities from the syngas under high-temperature conditions, and has a desulfurizing agent inlet at the top. The top gas outlet pipe of the dust removal and desulfurization furnace 4 is connected to the gas outlet of the heating furnace 5 and the gas inlet of the vertical furnace 6. In one embodiment, the top exhaust pipe of the dust removal and desulfurization furnace 4 is connected to the exhaust pipe of the heating furnace 5, and then to the vertical furnace 6. The top of the dust removal and desulfurization furnace 4 may also have a carbon dioxide inlet. The heating furnace 5 is used to heat the reducing gas, and the heated reducing gas mixes with the syngas discharged from the top exhaust pipe of the dust removal and desulfurization furnace 4 before entering the vertical furnace 6. The temperature of the mixed gas entering the vertical furnace 6 can be adjusted by controlling the heating temperature.

[0030] The vertical shaft furnace 6 has an iron ore pellet inlet at the top, a gas inlet at the bottom or side, a DRI outlet at the bottom, and a tail gas outlet at the top that is directly connected to the waste heat boiler 7. The mixed gas enters the vertical shaft furnace 6 through the gas inlet, and the iron ore pellets are added from the top of the vertical shaft furnace 6. Under the action of gravity, they move downwards and come into countercurrent contact with the reducing gas flowing upwards, realizing the reduction reaction of iron oxides to metallic iron, generating direct reduced iron (DRI), which is discharged from the bottom of the vertical shaft furnace 6.

[0031] The exhaust gas from the waste heat boiler 7, after waste heat recovery, is connected to the reducing gas preheater 8 via a pipeline. The waste heat boiler 7 is used to regulate the fluctuations in the top gas temperature of the vertical shaft furnace 6, protecting downstream equipment. In one embodiment, the system further includes a steam drum 13, connected to the waste heat boiler 7, for receiving high-temperature gas from the waste heat boiler 7 to generate steam.

[0032] The reducing gas preheater 8 is connected to the waste heat boiler 7, the circulating gas scrubbing tower 9, the compressor 11, and the gasifier 1. It transfers the gas input from the waste heat boiler 7 to the circulating gas scrubbing tower 9 and preheats the gas input from the compressor 11 using the gas from the waste heat boiler 7. The preheated gas is then input into the gasifier 1. In an optional embodiment, the outlet of the reducing gas preheater 8 can be connected to a venturi pipe, and then connected to the inlet of the circulating gas scrubbing tower 9 via the venturi pipe.

[0033] The circulating gas scrubbing tower 9 is connected to the reducing gas preheater 8, the shift converter 10, and the decarbonization device 12. After scrubbing and removing dust from the gas received from the reducing gas preheater 8, one path is input to the shift converter 10, and the other path is input to the decarbonization device 12 as a non-shift line. In one embodiment, according to the hydrogen-to-carbon ratio requirement, the circulating gas scrubbing tower 9 sends a portion of the gas through the shift converter to the decarbonization device; the other portion, which is used as fuel gas, is sent directly to the decarbonization device via the non-shift line.

[0034] The shift converter 10 is connected to the decarbonization unit 12 and / or the compressor 11, and is used to perform a water-gas shift reaction to adjust the CO to hydrogen ratio. In one embodiment, the shift converter 10 is connected to the decarbonization unit 12, and the gas after the water-gas shift reaction is input into the decarbonization unit 12.

[0035] The decarbonization device 12 is connected to the compressor 11 and is used to input the decarbonized gas into the compressor 11. The compressor 11 can pressurize the gas. The decarbonization device 12 includes a recirculation gas outlet, a carbon dioxide outlet, and a tail gas outlet. Carbon dioxide is discharged through the carbon dioxide outlet, a portion of the decarbonized gas is output to the compressor 11 through the recirculation gas outlet, and another portion of the decarbonized gas is output downstream through the tail gas outlet.

[0036] The gas outlet of the compression molding machine 11 is connected to the reducing gas preheater 8, the dust removal and desulfurization furnace 4, the heating furnace 5 and the vertical furnace 6, and outputs circulating gas to form a circulating gas treatment and reuse system, thereby forming a closed-loop operation structure to realize heat recovery and gas recycling.

[0037] In one example, the gas-based vertical shaft furnace system based on the co-production and recycling of reducing gas operates as follows: Raw coal and oxygen are fed into the gasifier 1 through the lower or side inlet to undergo a gasification reaction, generating high-temperature coal gas with CO and hydrogen as the main components, namely the aforementioned crude syngas. The high-temperature coal gas is drawn out from the top of the gasifier 1 and undergoes primary dust removal treatment by the dust collector 2. The separated solid particles are discharged through the ash removal tank 3.

[0038] After primary dust removal, the coal gas enters the dust removal and desulfurization furnace 4, where fine particulate matter and sulfides are further removed under high-temperature conditions. The dust removal and desulfurization furnace 4 is equipped with a high-temperature desulfurizing agent dosing system, which allows the coal gas to complete the desulfurization reaction at a relatively high temperature, thereby avoiding the sensible heat loss caused by deep cooling in the traditional wet desulfurization process.

[0039] After high-temperature purification, the gas is heated in furnace 5 to adjust its temperature to a suitable reduction temperature according to the operating temperature requirements of the vertical shaft furnace 6 before being fed into the lower or side part of the furnace. Iron ore pellets are added from the top of the furnace and move downwards under gravity, coming into countercurrent contact with the reducing gas flowing upwards, thus realizing the reduction reaction of iron oxides to metallic iron, generating direct reduced iron (DRI), which is discharged from the bottom of the furnace.

[0040] The high-temperature exhaust gas discharged from the top of the vertical shaft furnace 6 enters the waste heat boiler 7 for waste heat recovery, generating steam which is then transported to the steam drum 13. After waste heat recovery, the exhaust gas enters the reducing gas preheater 8 for heat exchange and preheating of the circulating gas. Subsequently, the gas enters the circulating gas scrubbing tower 9 for cooling and impurity removal.

[0041] The washed circulating gas is divided into two paths: one path enters the shift converter 10 for a water-gas shift reaction to adjust the CO to hydrogen ratio; the other path, as a non-shift line, directly enters the decarbonization unit 12. The shift and non-shift lines ultimately converge in the decarbonization unit 12. After CO2 removal in the decarbonization unit, the resulting composition-adjusted circulating reducing gas is input into the compressor 11 for pressurization. Part of the pressurized gas is returned to the dust removal and desulfurization furnace 4, the heating furnace 5, or directly to the vertical furnace 6 as circulating reducing gas; the other part enters the reducing gas preheater 8, where the gas input from the waste boiler 7 preheats this portion of the gas in the compressor. The preheated gas is then input into the gasifier 1. The CO2 removed by the decarbonization unit 12 is discharged through an independent pipeline and can be sent downstream for utilization as needed.

[0042] The gas-based vertical shaft furnace system provided by this invention, based on the synergistic preparation and recycling of reducing gas, allows the high-temperature reducing gas generated by coal gasification to be directly used for the reduction reaction in the vertical shaft furnace after dust removal and desulfurization under high-temperature conditions. The tail gas of the vertical shaft furnace is recycled after waste heat recovery, composition adjustment and decarbonization treatment, forming a closed-loop operation system. This system achieves comprehensive utilization of the sensible heat and chemical energy of the reducing gas, reduces deep cooling and repeated heating links, improves the overall thermal efficiency of the system and reduces energy consumption.

[0043] By employing the system provided by this invention, the following effects can also be achieved: (1) Improve the adaptability of energy structure and reduce the risk of dependence on natural gas and coke oven gas: Since this invention uses coal gasification to produce reducing gas, replacing the natural gas methane reforming route, the gas-based vertical shaft furnace direct reduction process no longer depends on the supply conditions of natural gas resources, thereby improving the adaptability of the process to my country's "rich in coal and scarce in gas" energy structure. This technical approach is conducive to reducing the operational risks caused by gas source dependence on imports or price fluctuations, and improving the feasibility of the project and energy security.

[0044] (2) Reduce the sensible heat loss caused by traditional wet purification: Since the present invention adopts high temperature dust removal and desulfurization technology, the reducing gas is purified under high temperature conditions, avoiding the process of reducing the gas to low temperature in the traditional "cooling-washing-desulfurization" path, thereby significantly reducing the sensible heat loss of the reducing gas and improving the overall thermal utilization efficiency of the system.

[0045] (3) Avoiding repeated heating and reducing system energy consumption: In the prior art, the reducing gas after desulfurization and purification usually needs to be heated again before it can enter the vertical furnace. The present invention completes the purification by maintaining the reducing gas at a high temperature and directly delivers it to the vertical furnace, avoiding the secondary heating process, reducing fuel or electricity consumption, reducing the overall energy consumption of the system, and helping to reduce CO2 emissions.

[0046] (4) Simplify the process flow and reduce equipment investment and operating costs: Since the deep cooling, wet washing and reheating devices are eliminated or weakened, the coal gasification-high temperature purification-vertical furnace integrated system constructed by the present invention is more compact, the number of equipment is reduced, and the system structure is simpler, thereby reducing the initial investment cost and long-term operation and maintenance cost.

[0047] (5) Improve the stability of reducing gas quality and enhance the stability of vertical furnace operation: The reducing gas is purified by high-temperature dust removal and desulfurization furnace, which can effectively reduce the sulfur content and dust content in the gas, making the reducing gas composition entering the vertical furnace more stable and clean, which is conducive to reducing the impact of sulfur on the quality of sponge iron products, and at the same time improving the operational stability of the vertical furnace and the metallization rate control level.

[0048] (6) Realize the cascade utilization of reducing gas heat: This invention directly uses the high-temperature reducing gas generated by coal gasification for the reduction reaction in the vertical furnace, realizing the cascade utilization of the sensible heat of the reducing gas within the system, so that the sensible heat of the gas directly participates in the process of ore heating and reduction reaction, improving the efficiency of thermal energy utilization and constructing a low-energy-consumption operation mode.

[0049] (7) Improve the feasibility of large-scale application of coal-based gas source in the field of gas-based direct reduction: Through the integrated design of the present invention, after solving the key technical obstacles such as high sulfur content of coal gasification, need for deep cooling and purification and repeated heating, the coal-based reducing gas can be stably adapted to the operating conditions of gas-based vertical furnace, thereby expanding the large-scale application space of gas-based direct reduction technology in the coal-based energy system. Example 2

[0050] Based on the same technical concept as Example 1, this embodiment of the invention provides a method for operating a gas-based vertical shaft furnace based on the synergistic preparation and recycling of reducing gas, applicable to the system provided in Example 1 and any of its embodiments. Specific implementation details of this method can be found in the relevant descriptions of Example 1, and will not be repeated here. Reference Figure 1 As shown, the method includes: Raw coal and oxygen are fed into the gasifier 1 through the feed inlet to undergo a gasification reaction, generating high-temperature syngas with CO and hydrogen as the main components. The generated high-temperature syngas is then output to the dust collector 2 through the top syngas outlet of the gasifier 1. The high-temperature syngas undergoes primary dust removal treatment through dust collector 2. The solid particles after dust removal and separation are discharged from the bottom of dust collector 2 into ash removal tank 3, and the syngas after dust removal treatment is output to dust removal and desulfurization furnace 4 through the gas outlet at the top of dust collector 2. High-temperature desulfurizing agent is added through the high-temperature desulfurizing agent dosing system built into the dust removal and desulfurization furnace 4, so that the syngas can complete the desulfurization reaction under high temperature conditions. The gas discharged from the heating furnace 5 is mixed with the syngas discharged from the dust removal and desulfurization furnace 4, and the temperature of the syngas is adjusted according to the operating temperature requirements of the vertical furnace 6. The iron ore pellets are reduced in the vertical furnace 6, and the generated reduced iron is discharged from the bottom and the high-temperature tail gas is discharged from the top. The waste heat of the high-temperature exhaust gas discharged from the vertical furnace 6 is recovered by the waste boiler 7. The exhaust gas after waste heat recovery enters the circulating gas scrubbing tower 9 through the reducing gas preheater 8 to complete the cooling and impurity removal. The circulating gas after being treated by the circulating gas scrubbing tower 9 is divided into two paths: one path first enters the shift converter 10 to carry out a water-gas shift reaction to adjust the ratio of CO to hydrogen, and then enters the decarbonization unit 12; the other path directly enters the decarbonization unit 12. After decarbonization treatment in the decarbonization device 12, the gas enters the compressor 11 and is then output as circulating gas to the dust removal and desulfurization furnace 4, the heating furnace 5, the vertical furnace 6, and the reducing gas preheater 8. The gas preheated by the reducing gas preheater 8 enters the gasifier 1.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas, characterized in that, It includes a gasifier (1), a dust collector (2), an ash removal tank (3), a dust removal and desulfurization furnace (4), a heating furnace (5), a vertical shaft furnace (6), a waste heat boiler (7), a reducing gas preheater (8), a circulating gas scrubbing tower (9), a conversion unit (10), a compressor (11), and a decarbonization unit (12); among which The feed inlet of the gasifier (1) is connected to the raw coal inlet and the oxygen inlet respectively to generate high-temperature syngas. The syngas outlet at the top of the gasifier (1) is directly connected to the inlet of the dust collector (2). The top gas outlet of the dust collector (2) is connected to the dust removal and desulfurization furnace (4), and the bottom is connected to the ash removal tank (3); The dust removal and desulfurization furnace (4) is used to remove dust and sulfide impurities from the synthesis gas under high temperature conditions. It is equipped with a desulfurizing agent inlet at the top. The gas outlet pipe at the top of the dust removal and desulfurization furnace (4) is connected to the gas outlet of the heating furnace (5) and the gas inlet of the vertical furnace (6). The top of the vertical furnace (6) is provided with an iron ore pellet inlet, the bottom or side is provided with a gas inlet, the bottom is provided with a DRI outlet, and the top is also provided with a tail gas outlet directly connected to the waste boiler (7). The exhaust gas from the waste boiler (7) after waste heat recovery is connected to the reducing gas preheater (8) through a pipeline; The reducing gas preheater (8) is connected to the waste boiler (7), the circulating gas scrubbing tower (9), the compressor (11) and the gasifier (1). It transmits the gas input from the waste boiler (7) to the circulating gas scrubbing tower (9) and uses the gas input from the waste boiler (7) to preheat the gas input from the compressor (11). The preheated gas is then input into the gasifier (1). The circulating gas scrubbing tower (9) is connected to the reducing gas preheater (8), the conversion device (10) and the decarbonization device (12). After the gas received from the reducing gas preheater (8) is scrubbed and dusted, one path is input to the conversion device (10), and the other path is input to the decarbonization device (12) as a non-conversion line. The conversion device (10) is connected to the decarbonization device (12) and / or the compressor (11) for carrying out water-gas conversion reaction to adjust the ratio of CO to hydrogen; The decarbonization device (12) is connected to the compressor (11) and is used to input the decarbonized gas into the compressor (11). The gas outlet of the compression molding machine (11) is connected to the reducing gas preheater (8), the dust removal and desulfurization furnace (4), the heating furnace (5) and the vertical furnace (6), and outputs circulating gas.

2. The gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas according to claim 1, characterized in that, It also includes a steam drum (13), which is connected to the waste boiler (7) to generate steam.

3. The gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas according to claim 1, characterized in that, The top exhaust pipe of the dust removal and desulfurization furnace (4) is connected to the exhaust pipe of the heating furnace (5), and then connected to the vertical furnace (6).

4. The gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas according to claim 1, characterized in that, The top of the dust removal and desulfurization furnace (4) is also equipped with a carbon dioxide inlet.

5. The gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas according to claim 1, characterized in that, The conversion device (10) is connected to the decarbonization device (12), and the gas after the water-gas conversion reaction is input into the decarbonization device (12).

6. The gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas according to claim 1, characterized in that, The decarbonization device (12) includes a circulating gas outlet, a carbon dioxide outlet, and a tail gas outlet. Carbon dioxide is discharged through the carbon dioxide outlet, a portion of the decarbonized gas is output to the compressor (11) through the circulating gas outlet, and another portion of the decarbonized gas is output downstream through the tail gas outlet.

7. The gas-based vertical shaft furnace system based on the synergistic preparation and recycling of reducing gas according to claim 1, characterized in that, Also includes: The washing tower is connected to the ash removal tank (3) and is used to wash the ash and slag output from the ash removal tank (3).

8. A method for operating a gas-based vertical shaft furnace based on the synergistic preparation and recycling of reducing gas, applied to the system according to any one of claims 1-7, characterized in that, include: Raw coal and oxygen are fed into the gasifier (1) through the feed port to produce high-temperature syngas with CO and hydrogen as the main components. The generated high-temperature syngas is output to the dust collector (2) through the top syngas outlet of the gasifier (1). The high-temperature syngas is subjected to primary dust removal treatment by the dust collector (2), and the solid particles after dust removal and separation are discharged to the dust removal tank (3) through the bottom of the dust collector (2), and the syngas after dust removal treatment is output to the dust removal and desulfurization furnace (4) through the gas outlet at the top of the dust collector (2). High-temperature desulfurizing agent is added through the high-temperature desulfurizing agent dosing system built into the dust removal and desulfurization furnace (4), so that the syngas completes the desulfurization reaction under high temperature conditions; The gas discharged from the heating furnace (5) is mixed with the syngas discharged from the dust removal and desulfurization furnace (4), and the temperature of the syngas is adjusted according to the operating temperature requirements of the vertical furnace (6). Iron ore pellets are reduced in a vertical furnace (6), and the generated reduced iron is discharged from the bottom and the high-temperature tail gas is discharged from the top. The high-temperature exhaust gas discharged from the vertical furnace (6) is recovered by the waste boiler (7). The exhaust gas after the waste heat recovery enters the circulating gas scrubbing tower (9) through the reducing gas preheater (8) to complete the cooling and impurity removal. The circulating gas after being treated by the circulating gas scrubbing tower (9) is divided into two paths: one path first enters the shift device (10) to carry out the water-gas shift reaction to adjust the ratio of CO to hydrogen, and then enters the decarbonization device (12); the other path directly enters the decarbonization device (12). After decarbonization treatment in the decarbonization device (12), the gas enters the compressor (11) and is then output as circulating gas to the dust removal and desulfurization furnace (4), the heating furnace (5), the vertical furnace (6) and the reducing gas preheater (8). The gas preheated by the reducing gas preheater (8) enters the gasifier (1).

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