System and method for coupling multi-stage graded biomass gasification with iron ore powder reduction

Abstract

The invention relates to the technical field of biomass energy utilization and metallurgical reduction, in particular to a system and a method for coupling multi-stage grading biomass gasification with iron ore powder reduction, which comprises a multi-stage grading fluidized bed gasifier connected with a waste heat boiler through a pipeline, the waste heat boiler is connected with the reduction reactor through a pipeline, the lower end of the reduction reactor is connected with the product tank through a pipeline, the upper end of the reduction reactor is connected with the external cyclone separator through a pipeline, and the external cyclone separator is connected with the water scrubbing tower through a pipeline. The lower end of the external cyclone separator is connected with a material returning device through a pipeline, the material returning device is connected with the reduction reactor through a pipeline, the equipment has high integration, the technological process is compact and efficient, the carbon emission is low, the efficient gasification technology and the fluidized bed reduction technology are organically coupled, the whole technological process does not need to depend on coke, and the energy consumption is low. And the external carbon emission is extremely low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biomass energy utilization and metallurgical reduction, and particularly relates to a system and method for multi-stage graded biomass gasification coupled with iron ore powder reduction. BACKGROUND

[0002] The steel industry is a key industry in terms of energy consumption and carbon emissions. The traditional blast furnace ironmaking process relies on fossil fuels such as coke, resulting in high CO2 emissions. In order to achieve the "double carbon" goal, it is urgent to develop new low-carbon or even zero-carbon ironmaking processes.

[0003] Among various low-carbon ironmaking paths, the direct reduced iron (DRI) process, especially the gas-based shaft furnace process, is considered an important direction to replace the traditional blast furnace due to its short process, low energy consumption, and pure product. However, the gas-based shaft furnace technology has very high requirements for the quality and supply stability of the reducing gas. At present, China lacks sufficient natural gas resources, which seriously restricts the popularization and application of this technology. Although some research has explored the use of coal gas or coke oven gas as a reducing gas source, the coal gas generated in the coal gasification process contains a lot of impurities and CO2, affecting the reduction efficiency and iron product quality. The coke oven gas reforming technology is only suitable for steel joint enterprises with large-scale coking facilities, and its scope of application is limited. More importantly, the above-mentioned technical routes have not fundamentally broken away from the dependence on fossil fuels.

[0004] Biomass energy, as a renewable and carbon-neutral energy form, is expected to achieve truly low-carbon or even "negative carbon" ironmaking when introduced into the steelmaking process. Existing technologies attempt to use biomass directly for ironmaking, such as preparing reducing gas through gasification or using it as an additive in pellet preparation, but there are still problems such as low gasification efficiency, poor quality of reducing gas, and low system integration. In particular, when coupling biomass gasification with existing shaft furnace reduction processes, how to achieve precise control of gas composition, efficient utilization of waste heat, and effective treatment of ash remains a technical difficulty.

[0005] To solve the above problems, some patent technologies have proposed some improvement schemes. For example, patent application CN114317855A provides a blast furnace ironmaking method, which prepares high-temperature and high-pressure synthesis gas (which can be derived from coal powder or biomass) through a gasification furnace, and sprays it together with pure oxygen from the lower part of the blast furnace to replace the traditional hot air and coal powder. Although this method improves the blast energy, reduces the coal consumption per ton of iron, and improves the coal gas quality to some extent, it still does not deviate from the basic framework of blast furnace smelting, continues to rely on coke, and has high requirements for the purity of gasification gas, which limits the large-scale flexible application of biomass. Another patent application CN120591483A proposes a CO2 recycling idea in a gas-based shaft furnace using biomass gasification gas as a reducing agent, which separates and recycles CO2 generated in the gasification and reduction processes to build an internal carbon cycle. However, this scheme relies on multiple CO2 separation devices, and the system is complex, with high energy consumption and investment cost. The integrated structure of the fluidized bed reduction reactor and the multi-stage cyclone preheater also has strict requirements on the particle size and cycle stability of the iron ore powder, making it difficult to implement in an industrialized manner. In addition, the biomass gasification furnace uses a single gasification section, and the content of effective components (CO, H2) in the synthesis gas is low; the reduction reactor uses a common fluidized bed form, and the iron ore powder is severely entrained, making it difficult to stably guarantee the metallization rate.

[0006] In summary, although the existing technology has made some breakthroughs in some aspects, there are still obvious shortcomings in system integration, energy efficiency optimization, and carbon emission reduction. Therefore, there is an urgent need to develop a new type of biomass gasification coupled reduction system that has good reducing gas quality, high system integration, full utilization of energy cascade, can realize efficient direct reduction of iron ore powder, and can minimize external carbon emissions. SUMMARY

[0007] The present application provides a multi-stage graded biomass gasification coupled iron ore powder reduction system and method to solve the problems of high energy consumption and large carbon emissions in the existing technology.

[0008] To achieve the above purpose, the following technical solutions are adopted: A multi-stage graded biomass gasification coupled iron ore powder reduction system, comprising a multi-stage graded fluidized bed gasification furnace, the multi-stage graded fluidized bed gasification furnace is connected with a waste heat boiler through a pipeline, the waste heat boiler is connected with a reduction reactor through a pipeline, the lower end of the reduction reactor is connected with a product tank through a pipeline, the upper end of the reduction reactor is connected with the inlet of an external cyclone separator through a pipeline, the gas outlet of the external cyclone separator is connected with a water washing tower through a pipeline, the solid outlet at the lower end of the external cyclone separator is connected with the inlet of a return device through a pipeline, and the outlet of the return device is connected with the reduction reactor through a pipeline; The reducing reactor is arranged as a conical cylindrical fluidized bed structure, an internal cyclone separator is fixedly installed inside the reducing reactor, a gas outlet is arranged at the upper end of the internal cyclone separator and extends to the outside of the top end of the reducing reactor, the gas outlet is connected to the inlet of an external cyclone separator through a pipeline, a purge gas inlet is connected to the left side wall of the upper end of the internal cyclone separator through a pipeline, the purge gas inlet is arranged on the outer side wall of the upper part of the reducing reactor, the lower part of the internal cyclone separator extends to the lower part of the reducing reactor, a fine iron ore feeding port and a return feeding inlet are arranged on the side wall of the middle part of the reducing reactor, the return feeding inlet is connected to the feeding inlet of a return device through a pipeline, two first reduction inlets are arranged on the side wall of the middle and lower parts of the reducing reactor, a first distribution plate is fixedly installed on the inner side wall of the lower part of the reducing reactor, a plurality of first through holes are arranged on the first distribution plate, a product outlet is arranged at the lower end of the first distribution plate, the product outlet extends to the outside of the reducing reactor through a pipeline, a product tank is connected to the product outlet through a pipeline, a third reduction gas inlet is arranged on the side wall of the pipeline of the product outlet, a second reduction gas inlet is arranged on the lower end surface of the reducing reactor, the first reduction gas inlet, the second reduction gas inlet and the third reduction gas inlet are connected to a waste heat boiler through a pipeline.

[0009] Further, the middle part of the furnace body of the multi-stage staged fluidized bed gasifier is arranged as a conical cylindrical structure, the upper and lower parts of the furnace body of the multi-stage staged fluidized bed gasifier are arranged as cylindrical structures, the multi-stage staged fluidized bed gasifier is divided into a dilute phase zone and a dense phase zone through the middle conical cylinder, a biomass feeding port is arranged on the side wall of the middle and lower parts of the multi-stage staged fluidized bed gasifier, two symmetrical gasifying agent inlets are arranged on the upper part of the multi-stage staged fluidized bed gasifier, one of the gasifying agent inlets is provided with a gasifying agent outlet at the upper part, one end of a conical distribution plate is fixedly installed on the inner wall of the lower part of the multi-stage staged fluidized bed gasifier, a plurality of second through holes are arranged on the conical distribution plate, the other end of the conical distribution plate is fixedly installed with a slag falling pipe, a center jet pipe is arranged inside the slag falling pipe, the center jet pipe extends to the outside of the slag falling pipe through the side wall of the slag falling pipe, a slag falling pipe gasifying agent inlet pipe is arranged on the side wall of the slag falling pipe, the slag falling pipe gasifying agent inlet pipe is arranged outside the multi-stage staged fluidized bed gasifier, a distribution plate gasifying agent inlet pipe is fixedly installed at the lower end of the multi-stage staged fluidized bed gasifier, one end of the distribution plate gasifying agent inlet pipe extends to the inside of the multi-stage staged fluidized bed gasifier.

[0010] Further, the waste heat boiler is provided with a hot side inlet and a hot side outlet, the hot side inlet is connected with the gasifying agent inlet through a pipeline, the hot side outlet is connected with the first reducing gas inlet, the second reducing gas inlet and the third reducing gas inlet through a pipeline, the upper end of the waste heat boiler is provided with a cold water inlet, the lower end of the waste heat boiler is provided with a steam outlet, the steam outlet is connected with the distribution plate gasifying agent inlet pipe, the center jet pipe and the slag falling pipe gasifying agent inlet pipe through a pipeline.

[0011] Further, the angle α between the conic generatrix of the upper conic cylindrical structure of the multi-stage classified fluidized bed gasification furnace and the central axis is set to 1-20°, the angle β between the conic generatrix of the conic distribution plate and the central axis is set to 20-50°, the height between the gasifying agent inlet and the biomass feeding port is set to 1 / 3-1 / 2 of the height of the multi-stage classified fluidized bed gasification furnace, the opening rate of the conic distribution plate is 0.5%-4%, and the aperture of the No. 1 through hole is set to 2-6 mm.

[0012] Further, the angle γ between the conic generatrix of the conic cylindrical structure of the reducing reactor and the central axis is 1-20°, the height between the first reducing gas inlet and the fine iron ore feeding port is set to 1 / 3-1 / 2 of the height of the reducing reactor, the opening rate of the No. 1 distribution plate is 0.5%-4%, and the aperture of the No. 1 through hole is set to 2-6 mm.

[0013] A multi-stage classified biomass gasification coupled with iron ore powder reduction method, comprising the following steps: Multi-stage classified biomass gasification furnace reaction step: biomass raw materials with a particle size of 1-10 mm are added to the multi-stage classified fluidized bed gasification furnace from the biomass feeding port, the gasifying agent is introduced from the distribution plate gasifying agent inlet pipe, the center jet pipe and the slag falling pipe gasifying agent inlet pipe, the temperature of the dense phase zone is controlled at 700-1000℃, the gasifying agent is introduced from the gasifying agent inlet, the temperature of the dilute phase zone is controlled at 1000-1300℃, and the gas-solid mixture generated by the multi-stage classified fluidized bed gasification furnace is separated by the slag falling pipe and the center jet pipe, and the separated solid ash is discharged through the slag falling pipe; Waste heat recovery and reducing gas preparation step: the high-temperature vaporization gas is sent to the waste heat boiler to recover sensible heat through the gasifying agent outlet, cold water is introduced through the cold water inlet to generate water vapor, and the water vapor produced by the waste heat boiler is sent back to the distribution plate gasifying agent inlet pipe, the center jet pipe and the slag falling pipe gasifying agent inlet pipe as the gasifying agent through the steam outlet; The reduction reactor reaction step: the hot boiler transports the biomass gasification gas to the first reduction gas inlet, the second reduction gas inlet and the third reduction gas inlet through a pipeline after being cooled, the biomass gasification gas is reacted in the reduction reactor to generate a gas-solid mixture, the gas-solid mixture is subjected to primary gas-solid separation and particle instant backmixing through an internal cyclone separator, at the same time, the fine iron ore feed inlet receives fine iron ore powder material, the iron ore powder is subjected to reduction reaction with the reducing gas, and finally, metallized iron with a metallization rate of 95% or more is obtained, the metallized iron is transported from the product outlet to the product tank, the internal temperature of the reduction reactor is set to 500-700 DEG C, the working pressure is set to 0.1-1.5 MPa, and the superficial gas velocity is set to 0.5-1.2 m / s; The material circulation and gas purification step: the gas-solid mixture is transported to the external cyclone separator through a pipeline, the small solid particles separated by the external cyclone separator enter the return device and are returned to the reduction reactor through the return inlet for material circulation, and the reducing gas is transported to the water washing tower through a pipeline for purification treatment.

[0014] Further, the oxygen volume concentration of the gasification agent introduced into the distribution plate gasification agent inlet pipe, the center jet pipe and the slag falling pipe gasification agent inlet pipe is 10-25%, 20-70% and 0-25% respectively, and the gasification agent introduced into the gasification inlet is pure oxygen.

[0015] Further, the main component of the fine iron ore powder is Fe3O4, and the particle size range is 0-0.15 mm.

[0016] Compared with the prior art, the present application has the following advantages: 1. The equipment of the present application has high integration, compact process flow, low carbon emission, and is organically coupled with the high-efficiency gasification technology and the fluidized bed reduction process, uses renewable and carbon-neutral biomass as raw material, replaces traditional fossil fuels from the source, and does not need to rely on coke in the whole process, so the external carbon emission is extremely low, which is a green ironmaking technology.

[0017] 2. The present application adopts a reduction reactor, combines an internal cyclone separator and an external cyclone separator for secondary separation and return of materials, greatly prolongs the residence time of the iron ore powder in the reduction reactor, strengthens the gas-solid contact, and realizes rapid and deep reduction of the iron ore powder.

[0018] 3. The present application adopts a multi-stage staged fluidized bed gasification furnace, different concentrations of gasification agents are introduced into different regions, and the staged and gradient gasification of biomass is successfully realized, which significantly improves the carbon conversion rate and the gasification intensity. In the generated synthesis gas, the content of effective components is high, and the content of tar and methane is low, the quality is stable, and the demand for efficient reduction is completely met.

[0019] 4. This invention efficiently recovers the sensible heat of high-temperature gasification gas through a waste heat boiler. The generated steam can directly enter a multi-stage graded fluidized bed gasifier to act as a gasifying agent, realizing the cascade and closed-loop effect of internal energy connection, and significantly reducing external energy consumption and operating costs.

[0020] 5. By adjusting the ratio of the gasifying agent and the reaction conditions, the system of this invention can adapt well to different types of biomass raw materials and iron ore powder particle size ranges, flexibly cope with a variety of raw materials, thereby ensuring the stable operation and wide applicability of the process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a schematic diagram of the reduction reactor of the present invention; Figure 3 This is a schematic diagram of the structure of the multi-stage staged fluidized bed gasifier of the present invention; In the diagram, the components are: 1. Multi-stage graded fluidized bed gasifier; 101. Biomass feed inlet; 102. Gasifying agent inlet; 103. Conical distribution plate; 104. Slag discharge pipe; 105. Central jet pipe; 106. Slag discharge pipe gasifying agent inlet pipe; 107. Distribution plate gasifying agent inlet pipe; 108. Gasifying agent outlet; 2. Waste heat boiler; 3. Reduction reactor; 3. Built-in cyclone separator; 301. Gas outlet; 302. Purge inlet; 303. Iron concentrate feed inlet; 304. Return material inlet; 305. First reducing gas inlet; 306. First distribution plate; 307. Product outlet; 308. Third reducing gas inlet; 309. Second reducing gas inlet; 310. Product tank; 4. External cyclone separator; 5. Water washing tower; 6. Return material device; 7. Detailed Implementation

[0022] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments. Example

[0023] like Figure 1 As shown, a multi-stage graded biomass gasification coupled with iron ore powder reduction system includes a multi-stage graded fluidized bed gasifier 1. The multi-stage graded fluidized bed gasifier 1 is connected to a waste heat boiler 2 via a pipeline. The waste heat boiler 2 is connected to a reduction reactor 3 via a pipeline. The lower end of the reduction reactor 3 is connected to a product tank 4 via a pipeline. The upper end of the reduction reactor 3 is connected to the inlet of an external cyclone separator 5 via a pipeline. The outlet of the external cyclone separator 5 is connected to a water washing tower 6 via a pipeline. The solid outlet at the lower end of the external cyclone separator 5 is connected to the inlet of a return material device 7 via a pipeline. The outlet of the return material device 7 is connected to the reduction reactor 3 via a pipeline. like Figure 2As shown, the reduction reactor 3 is provided in a conical cylinder fluidized bed structure, an internal cyclone 301 is fixedly installed inside the reduction reactor 3, a gas outlet 302 is provided at the upper end of the internal cyclone 301 and extends to the outside of the top end of the reduction reactor 3, the gas outlet 302 is connected to the inlet of the external cyclone 5 through a pipeline, a purge gas inlet 303 is connected to the left side wall of the upper end of the internal cyclone 301 through a pipeline, the purge gas inlet 303 is provided on the upper outer side wall of the reduction reactor 3, the lower part of the internal cyclone 301 extends to the lower part of the reduction reactor 3, a fine iron ore inlet 304 and a return material inlet 305 are provided on the side wall of the middle part of the reduction reactor 3, the return material inlet 305 is connected to the inlet of the return material device 7 through a pipeline, two first reduction gas inlets 306 are provided on the side wall of the middle and lower part of the reduction reactor 3, a first distribution plate 307 is fixedly installed on the inner side wall of the lower part of the reduction reactor 3, a plurality of first through holes are provided on the first distribution plate 307, a product outlet 308 is provided at the lower end of the first distribution plate 307, the product outlet 308 extends to the outside of the reduction reactor 3 through a pipeline, the product outlet 308 is connected to the product tank 4 through a pipeline, a third reduction gas inlet 309 is provided on the side wall of the pipeline of the product outlet 308, a second reduction gas inlet 310 is provided on the lower end face of the reduction reactor 3, the first reduction gas inlet 306, the second reduction gas inlet 310 and the third reduction gas inlet 309 are connected to the waste heat boiler 2 through a pipeline.

[0024] As Figure 3As shown, the middle part of the furnace body of the multi-stage staged fluidized bed gasifier 1 is provided as a conical cylinder structure, the upper and lower parts of the furnace body of the multi-stage staged fluidized bed gasifier 1 are provided as cylindrical cylinder structures, the inside of the multi-stage staged fluidized bed gasifier 1 is divided into a dilute phase zone and a dense phase zone by the middle conical cylinder, a biomass feeding port 101 is arranged on the side wall of the lower part of the multi-stage staged fluidized bed gasifier 1, the dilute phase zone is arranged above the biomass feeding port 101, and the dense phase zone is arranged below the biomass feeding port 101, two symmetrical gasifying agent inlets 102 are arranged on the upper part of the multi-stage staged fluidized bed gasifier 1, one of the gasifying agent inlets 102 is provided with a gasifying agent outlet 108 on the upper part, one end of a conical distribution plate 103 is fixedly installed on the inner wall of the lower part of the multi-stage staged fluidized bed gasifier 1, a plurality of second through holes are arranged on the conical distribution plate 103, a slag falling pipe 104 is fixedly installed on the other end of the conical distribution plate 103, a center jet pipe 105 is arranged in the slag falling pipe 104, the center jet pipe 105 extends to the outside of the slag falling pipe 104 through the side wall of the slag falling pipe 104, a slag falling pipe gasifying agent inlet pipe 106 is arranged on the side wall of the slag falling pipe 104, the slag falling pipe gasifying agent inlet pipe 106 is arranged outside the multi-stage staged fluidized bed gasifier 1, and a distribution plate gasifying agent inlet pipe 107 is fixedly installed on the lower end of the multi-stage staged fluidized bed gasifier 1, one end of the distribution plate gasifying agent inlet pipe 107 extends to the inside of the multi-stage staged fluidized bed gasifier 1.

[0025] The waste heat boiler 2 is provided with a hot side inlet and a hot side outlet, the hot side inlet is connected with the gasifying agent outlet 108 through a pipeline, the hot side outlet is connected with the first reducing gas inlet 306, the second reducing gas inlet 310 and the third reducing gas inlet 309 through a pipeline, the upper end of the waste heat boiler 2 is provided with a cold water inlet, the lower end of the waste heat boiler 2 is provided with a steam outlet, and the steam outlet is connected with the distribution plate gasifying agent inlet pipe 107, the center jet pipe 105 and the slag falling pipe gasifying agent inlet pipe 106 through a pipeline.

[0026] The included angle α between the conical generatrix of the conical cylinder structure on the upper part of the multi-stage staged fluidized bed gasifier 1 and the center axis is 5°, the included angle β between the conical generatrix of the conical distribution plate 103 and the center axis is 30°, the height between the gasifying agent inlet 102 and the biomass feeding port 101 is 1 / 2 of the height of the multi-stage staged fluidized bed gasifier 1, the opening rate of the conical distribution plate 103 is 1.5%, and the hole diameter of the second through hole is 4 mm.

[0027] The included angle γ between the conical generatrix of the conical cylinder structure of the reducing reactor 3 and the center axis is 8°, the height between the first reducing gas inlet 306 and the fine iron ore feeding port 304 is 1 / 2 of the height of the reducing reactor 3, the opening rate of the first distribution plate 307 is 1.2%, and the hole diameter of the first through hole is 3 mm.

[0028] A method for multi-stage hierarchical biomass gasification coupled with iron ore powder reduction, comprising the following steps: The reaction step of the multi-stage hierarchical biomass gasification furnace: wood chip biomass raw materials with a particle size of 1-10 mm are added to the multi-stage hierarchical fluidized bed gasification furnace 1 from the biomass feed inlet 101, the gasification agent is introduced from the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slag falling pipe gasification agent inlet pipe 106, the temperature of the dense phase zone is controlled at 750℃, the gasification agent is introduced from the gasification agent inlet 102, the temperature of the dilute phase zone is controlled at 1250℃, and the gas-solid mixture produced by the multi-stage hierarchical fluidized bed gasification furnace 1 is separated by the slag falling pipe 104 and the center jet pipe 105, and the separated solid ash is discharged through the slag falling pipe 104; The waste heat recovery and reduction gas preparation step: the high-temperature vaporization gas is sent to the waste heat boiler 2 from the gasification agent outlet to recover sensible heat, cold water is introduced through the cold water inlet 203, and the temperature is cooled to 650℃ to generate water vapor, and the water vapor produced by the waste heat boiler 2 is sent back to the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slag falling pipe gasification agent inlet pipe 106 as the gasification agent; The reaction step of the reduction reactor 3: the hot boiler sends the biomass gasification gas to the first reduction gas inlet 306, the second reduction gas inlet 310 and the third reduction gas inlet 309 through the pipeline after cooling, the CO content in the biomass gasification gas is 45%, the H2 content is 38%, the biomass gasification gas reacts in the reduction reactor 3 to generate a gas-solid mixture, the gas-solid mixture is subjected to primary gas-solid separation and particle instant backmixing through the built-in cyclone separator 301, at the same time, the fine iron ore feed inlet 304 receives fine iron ore powder material, the main component of the fine iron ore powder is Fe3O4, the particle size range is 0-0.15mm, the iron ore powder is subjected to reduction reaction with the reducing gas, and finally the metallized iron with a metallization rate of 95.5% is obtained, the metallized iron is transported to the product tank 4 inside from the product outlet 308, the internal temperature of the reduction reactor 3 is set to 550~600℃, the working pressure is set to 0.8MPa, and the superficial gas velocity is set to 0.8~1m / s; The material circulation and gas purification step: the gas-solid mixture is transported to the external cyclone separator 5 through the pipeline from the gas outlet 302, the separated small solid particles enter the return device 7, and are returned to the reduction reactor 3 through the return inlet 305 for material circulation, and the reducing gas is transported to the water washing tower 6 for purification treatment through the pipeline from the external cyclone separator 5.

[0029] The oxygen volume concentration of the gasification agent entering into the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slagging pipe gasification agent inlet pipe 106 is 15%, 40% and 15% respectively, and the gasification agent entering into the gasification agent inlet 102 is pure oxygen. Embodiment

[0030] The process flow of the embodiment is consistent with the system connection relationship of Embodiment 1, but there are differences in raw material selection, operating parameters and product indicators. The specific implementation process is as follows: The included angle α of the conical generatrix of the conical cylindrical structure at the upper part of the multi-stage classified fluidized bed gasification furnace 1 and the central axis is set to 10°, the included angle β of the conical generatrix of the conical distribution plate 103 and the central axis is set to 40°, the height between the gasification agent inlet 102 and the biomass feed inlet 101 is set to 2 / 5 of the height of the multi-stage classified fluidized bed gasification furnace 1, the opening rate of the conical distribution plate 103 is 1.5%, and the aperture of the first through hole is set to 4mm.

[0031] The included angle γ of the conical generatrix of the conical cylindrical structure of the reduction reactor 3 and the central axis is 15°, the height between the first reduction gas inlet 306 and the fine iron ore feed inlet 304 is set to 1 / 3 of the height of the reduction reactor 3, the opening rate of the first distribution plate 307 is 2%, and the aperture of the first through hole is set to 4mm.

[0032] A multi-stage classified biomass gasification coupled with iron ore powder reduction method, comprising the following steps: Multi-stage classified biomass gasification furnace reaction step: wood chip biomass raw material with a particle size of 1-10mm is added to the multi-stage classified fluidized bed gasification furnace 1 from the biomass feed inlet 101, gasification agent is introduced from the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slagging pipe gasification agent inlet pipe 106, the temperature of the dense phase zone is controlled at 780℃, the gasification agent is introduced from the gasification agent inlet 102, and the temperature of the dilute phase zone is controlled at 1280℃. The gas-solid mixture generated by the multi-stage classified fluidized bed gasification furnace 1 is separated by the slagging pipe 104 and the center jet pipe 105, and the separated solid ash is discharged through the slagging pipe 104; Waste heat recovery and reduction gas preparation step: the high-temperature vaporization gas is sent to the waste heat boiler 2 through the gasification agent outlet to recover sensible heat, cold water is introduced through the cold water inlet 203, and the temperature is cooled to 680℃ to generate steam. The steam produced by the waste heat boiler 2 is sent back to the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slagging pipe gasification agent inlet pipe 106 as gasification agent through the steam outlet; Reduction reactor 3 reaction step: the hot boiler transports the biomass gasification gas to the first reduction gas inlet 306, the second reduction gas inlet 310 and the third reduction gas inlet 309 through the pipeline after it is cooled, the biomass gasification gas contains 46.5% CO and 39% H2, the biomass gasification gas reacts in the reduction reactor 3 to generate a gas-solid mixture, the gas-solid mixture is subjected to primary gas-solid separation and particle instant backmixing through the built-in cyclone separator 301, and the fine iron ore feed inlet 304 receives the fine iron ore powder material inwardly, the fine iron ore powder mainly contains Fe3O4 and has a particle size range of 0-0.1 mm, the fine iron ore powder is subjected to reduction reaction with the reducing gas, and finally the metallized iron with a metallization rate of 96.5% is obtained, the metallized iron is transported from the product outlet 308 to the inside of the product tank 4, the inside temperature of the reduction reactor 3 is set to 580-620 ℃, the working pressure is set to 0.9 MPa, and the superficial gas velocity is set to 0.7-0.95 m / s; Material circulation and gas purification step: the gas-solid mixture is transported by the gas outlet 302 to the external cyclone separator 5 through the pipeline for separation, the separated small solid particles enter the return device 7, are returned to the reduction reactor 3 through the return inlet 305, and are subjected to material circulation, and the reducing gas is transported by the external cyclone separator 5 to the water washing tower 6 through the pipeline for purification treatment.

[0033] The oxygen volume concentration of the gasification agent entering the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slag falling pipe gasification agent inlet pipe 106 is 20%, 40% and 20% respectively, and the gasification agent entering the gasification agent inlet 102 is pure oxygen. Embodiment

[0034] The process flow of the embodiment is consistent with the system connection relationship of embodiment 1, but there are differences in raw material selection, operating parameters and product indicators, and the specific implementation process is as follows: The included angle α between the conical generatrix of the conical cylindrical structure of the multi-stage staged fluidized bed gasification furnace 1 and the center axis is set to 5°, the included angle β between the conical generatrix of the conical distribution plate 103 and the center axis is set to 30°, the height between the gasification agent inlet 102 and the biomass feed inlet 101 is set to 1 / 2 of the height of the multi-stage staged fluidized bed gasification furnace 1, the opening rate of the conical distribution plate 103 is 1.5%, and the hole diameter of the second through hole is set to 4 mm.

[0035] The included angle γ between the conical generatrix of the conical cylindrical structure of the reduction reactor 3 and the center axis is 8°, the height between the first reduction gas inlet 306 and the fine iron ore feed inlet 304 is set to 1 / 2 of the height of the reduction reactor 3, the opening rate of the first distribution plate 307 is 1.2%, and the hole diameter of the first through hole is set to 3 mm.

[0036] A method for multi-stage hierarchical biomass gasification coupled with iron ore powder reduction, comprising the following steps: Multi-stage hierarchical biomass gasification furnace reaction step: rice hull biomass raw materials with a particle size of 1-10 mm are added to the multi-stage hierarchical fluidized bed gasification furnace 1 from the biomass feed inlet 101, and the gasification agent is introduced from the distribution plate gasification agent inlet pipe 107, the center jet pipe 105, and the slag falling pipe gasification agent inlet pipe 106, the temperature of the dense phase zone is controlled at 750℃, the gasification agent is introduced from the gasification agent inlet 102, the temperature of the dilute phase zone is controlled at 1280℃, and the gas-solid mixture produced by the multi-stage hierarchical fluidized bed gasification furnace 1 is separated by the slag falling pipe 104 and the center jet pipe 105, and the separated solid ash is discharged through the slag falling pipe 104; Waste heat recovery and reduction gas preparation step: the high-temperature vaporization gas is sent to the waste heat boiler 2 from the gasification agent outlet to recover sensible heat, cold water is introduced through the cold water inlet 203, and the temperature is cooled to 650℃ to generate water vapor, and the water vapor produced by the waste heat boiler 2 is sent back to the distribution plate gasification agent inlet pipe 107, the center jet pipe 105, and the slag falling pipe gasification agent inlet pipe 106 as a gasification agent through the steam outlet; Reduction reactor 3 reaction step: the hot boiler sends the biomass gasification gas to the first reduction gas inlet 306, the second reduction gas inlet 310, and the third reduction gas inlet 309 through the pipeline after cooling, the CO content in the biomass gasification gas is 48%, the H2 content is 40%, the biomass gasification gas reacts in the reduction reactor 3 to generate a gas-solid mixture, the gas-solid mixture is subjected to primary gas-solid separation and particle instant backmixing through the built-in cyclone separator 301, and at the same time, the fine iron ore inlet 304 receives fine iron ore powder material, the main component of the fine iron ore powder is Fe3O4, the particle size range is 0-0.1 mm, the iron ore powder is subjected to reduction reaction with the reducing gas, and finally metallized iron with a metallization rate of 96% is obtained, the metallized iron is transported to the product tank 4 inside from the product outlet 308, the internal temperature of the reduction reactor 3 is set to 600-630℃, the working pressure is set to 1 MPa, and the superficial gas velocity is set to 0.8-1 m / s; Material circulation and gas purification step: the gas-solid mixture is transported to the external cyclone separator 5 through the pipeline from the gas outlet 302 for separation, the separated small solid particles enter the return device 7 and are returned to the reduction reactor 3 through the return inlet 305 for material circulation, and the reducing gas is transported to the water washing tower 6 through the pipeline from the external cyclone separator 5 for purification treatment.

[0037] The oxygen volume concentration of the gasification agent introduced into the distribution plate gasification agent inlet pipe 107, the center jet pipe 105, and the slag falling pipe gasification agent inlet pipe 106 is 15%, 40%, and 15% respectively, and the gasification agent introduced from the gasification agent inlet 102 is pure oxygen. Example

[0038] The process flow of the embodiment is consistent with the system connection relationship of Example 1, but there are differences in raw material selection, operating parameters and product indicators. The specific implementation process is as follows: The included angle α of the conic generatrix of the conical cylindrical structure at the upper part of the multi-stage classification fluidized bed gasifier 1 and the central axis is set to 10°, the included angle β of the conic generatrix of the conical distribution plate 103 and the central axis is set to 40°, the height between the gasification agent inlet 102 and the biomass feed inlet 101 is set to 1 / 2 of the height of the multi-stage classification fluidized bed gasifier 1, the opening rate of the conical distribution plate 103 is 1.5%, and the aperture of the second through hole is set to 4mm.

[0039] The included angle γ of the conic generatrix of the conical cylindrical structure of the reduction reactor 3 and the central axis is 15°, the height between the first reduction gas inlet 306 and the fine iron ore feed inlet 304 is set to 1 / 3 of the height of the reduction reactor 3, the opening rate of the first distribution plate 307 is 2%, and the aperture of the first through hole is set to 4mm.

[0040] A multi-stage classification biomass gasification coupled with iron ore powder reduction method, comprising the following steps: Multi-stage classification biomass gasification reactor step: biomass raw material of rice husk with particle size of 1-10mm is added to the multi-stage classification fluidized bed gasifier 1 from the biomass feed inlet 101, gasification agent is introduced from the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slagging pipe gasification agent inlet pipe 106, the temperature of the dense phase zone is controlled at 770℃, the gasification agent is introduced from the gasification agent inlet 102, the temperature of the dilute phase zone is controlled at 1320℃, and the gas-solid mixture produced by the multi-stage classification fluidized bed gasifier 1 is separated by the slagging pipe 104 and the center jet pipe 105, and the separated solid ash is discharged through the slagging pipe 104; Waste heat recovery and reduction gas preparation step: high-temperature vaporization gas is sent to the waste heat boiler 2 from the gasification agent outlet to recover sensible heat, cold water is introduced through the cold water inlet 203, cooled to 660℃, and water vapor is generated, and the water vapor produced by the waste heat boiler 2 is sent back to the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slagging pipe gasification agent inlet pipe 106 as gasification agent; The reduction reactor 3 reaction step: the hot boiler transports the biomass gasification gas to the first reduction gas inlet 306, the second reduction gas inlet 310 and the third reduction gas inlet 309 through the pipeline after being cooled, the biomass gasification gas is 49% CO and 41% H2, the biomass gasification gas is reacted in the reduction reactor 3 to generate a gas-solid mixture, the gas-solid mixture is subjected to primary gas-solid separation and particle instant back mixing through the built-in cyclone separator 301, and the fine iron ore feed inlet 304 receives the fine iron ore powder material inwardly, the fine iron ore powder mainly contains Fe3O4, the particle size range is 0-0.1 mm, the fine iron ore powder is subjected to reduction reaction with the reducing gas, and finally the metallized iron with a metallization rate of 96.8% is obtained, the metallized iron is transported from the product outlet 308 to the inside of the product tank 4, the internal temperature of the reduction reactor 3 is set to 610-630℃, the working pressure is set to 1.2 MPa, and the superficial gas velocity is set to 0.7-0.95 m / s; The material circulation and gas purification step: the gas-solid mixture is transported by the gas outlet 302 to the external cyclone separator 5 through the pipeline for separation, the separated small solid particles enter the return device 7, return to the reduction reactor 3 through the return inlet 305, and the material circulation is carried out, and the reducing gas is transported by the external cyclone separator 5 to the water washing tower 6 through the pipeline for purification treatment.

[0041] The oxygen volume concentration of the gasification agent entering the distribution plate gasification agent inlet pipe 107, the center jet pipe 105 and the slag falling pipe gasification agent inlet pipe 106 is 20%, 40% and 20% respectively, and the gasification agent entering the gasification agent inlet 102 is pure oxygen.

[0042] The above shows and describes the main features and advantages of the present application, and it is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0043] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments which can be understood by those skilled in the art.

Claims

1. A system for multi-stage staged biomass gasification coupled with iron ore fines reduction, characterized in that: The application relates to a multi-stage grading fluidized bed gasification furnace (1) which is connected with a waste heat boiler (2) through a pipeline, the waste heat boiler (2) is connected with a reduction reactor (3) through a pipeline, the lower end of the reduction reactor (3) is connected with a product tank (4) through a pipeline, the upper end of the reduction reactor (3) is connected with the inlet of an external cyclone separator (5) through a pipeline, the gas outlet of the external cyclone separator (5) is connected with a water washing tower (6) through a pipeline, the solid outlet of the lower end of the external cyclone separator (5) is connected with the feeding inlet of a returning device (7) through a pipeline, and the discharging outlet of the returning device (7) is connected with the reduction reactor (3) through a pipeline. The reduction reactor (3) is arranged in a conical cylinder-shaped fluidized bed structure, an internal cyclone separator (301) is fixedly arranged in the reduction reactor (3), a gas outlet (302) is arranged at the upper end of the internal cyclone separator (301) and extends to the outside of the top end of the reduction reactor (3), the gas outlet (302) is connected with the inlet of the external cyclone separator (5) through a pipeline, a purging gas inlet (303) is arranged on the left side wall of the upper end of the internal cyclone separator (301) through a pipeline, the purging gas inlet (303) is arranged on the upper outer side wall of the reduction reactor (3), the lower part of the internal cyclone separator (301) extends to the lower part of the reduction reactor (3), a fine iron ore feeding inlet (304) and a returning inlet (305) are arranged on the side wall of the middle part of the reduction reactor (3), the returning inlet (305) is connected with the feeding inlet of the returning device (7) through a pipeline, two first reduction gas inlets (306) are arranged on the side wall of the middle and lower parts of the reduction reactor (3), a first distribution plate (307) is fixedly arranged on the inner side wall of the lower part of the reduction reactor (3), a plurality of first through holes are arranged on the first distribution plate (307), a product outlet (308) is arranged at the lower end of the first distribution plate (307), the product outlet (308) extends to the outside of the reduction reactor (3) through a pipeline, the product outlet (308) is connected with the product tank (4) through a pipeline, a third reduction gas inlet (309) is arranged on the pipeline side wall of the product outlet (308), a second reduction gas inlet (310) is arranged on the lower end face of the reduction reactor (3), and the first reduction gas inlet (306), the second reduction gas inlet (310) and the third reduction gas inlet (309) are connected with the waste heat boiler (2) through pipelines.

2. The system for multi-stage hierarchical biomass gasification coupled with iron ore fines reduction according to claim 1, characterized in that: The middle part of the furnace body of the multi-stage grading fluidized bed gasifier (1) is provided with a conical cylindrical structure, the upper and lower parts of the furnace body of the multi-stage grading fluidized bed gasifier (1) are provided with cylindrical structures, the inside of the multi-stage grading fluidized bed gasifier (1) is divided into a dilute phase zone and a dense phase zone by the middle conical cylinder, a biomass feeding port (101) is arranged on the side wall of the lower part of the multi-stage grading fluidized bed gasifier (1), two symmetrical gasifying agent inlets (102) are arranged on the upper part of the multi-stage grading fluidized bed gasifier (1), a gasifying agent outlet (108) is arranged on the upper part of one of the gasifying agent inlets (102), one end of a conical distribution plate (103) is fixedly installed on the inner wall of the lower part of the multi-stage grading fluidized bed gasifier (1), a plurality of second through holes are arranged on the conical distribution plate (103), the other end of the conical distribution plate (103) is fixedly installed with a slag falling pipe (104), the inside of the slag falling pipe (104) is provided with a center jet pipe (105), the center jet pipe (105) extends to the outside of the slag falling pipe (104) through the side wall of the slag falling pipe (104), a slag falling pipe gasifying agent inlet pipe (106) is arranged on the side wall of the slag falling pipe (104), the slag falling pipe gasifying agent inlet pipe (106) is arranged outside the multi-stage grading fluidized bed gasifier (1), a distribution plate gasifying agent inlet pipe (107) is fixedly installed on the lower end of the multi-stage grading fluidized bed gasifier (1), one end of the distribution plate gasifying agent inlet pipe (107) extends to the inside of the multi-stage grading fluidized bed gasifier (1).

3. The system for multi-stage hierarchical biomass gasification coupled with iron ore fines reduction according to claim 1, characterized in that: A hot side inlet and a hot side outlet are arranged on the waste heat boiler (2), the hot side inlet is connected with the gasifying agent outlet (108) through a pipeline, the hot side outlet is connected with a first reducing gas inlet (306), a second reducing gas inlet (310) and a third reducing gas inlet (309) through a pipeline, a cold water inlet is arranged on the upper end of the waste heat boiler (2), a steam outlet is arranged on the lower end of the waste heat boiler (2), the steam outlet is connected with the distribution plate gasifying agent inlet pipe (107), the center jet pipe (105) and the slag falling pipe gasifying agent inlet pipe (106) through a pipeline.

4. The system for multi-stage hierarchical biomass gasification coupled with iron ore fines reduction according to claim 2, wherein: The included angle α between the conical generatrix of the upper conical cylindrical structure of the multi-stage grading fluidized bed gasifier (1) and the center axis is 1-20°, the included angle β between the conical generatrix of the conical distribution plate (103) and the center axis is 20-50°, the height between the gasifying agent inlet (102) and the biomass feeding port (101) is 1 / 3-1 / 2 of the height of the multi-stage grading fluidized bed gasifier (1), the opening rate of the conical distribution plate (103) is 0.5%-4%, the aperture of the second through hole is 2-6mm.

5. The system for multi-stage hierarchical biomass gasification coupled with iron ore fines reduction according to claim 1, wherein: The included angle γ between the conical generatrix of the conical cylindrical structure of the reducing reactor (3) and the center axis is 1-20°, the height between the first reducing gas inlet (306) and the fine iron ore feeding port (304) is 1 / 3-1 / 2 of the height of the reducing reactor (3), the opening rate of the first distribution plate (307) is 0.5%-4%, the aperture of the first through hole is 2-6mm.

6. A process for multi-stage staged biomass gasification coupled with iron ore fines reduction according to any one of claims 2 to 5, characterized in that, The method comprises the following steps: The multi-stage staged fluidized bed gasifier reaction step: biomass raw materials with a particle size of 1-10 mm are added into the multi-stage staged fluidized bed gasifier (1) from a biomass feeding port (101), gasification agents are introduced from a distribution plate gasification agent inlet pipe (107), a center jet pipe (105), and a slagging pipe gasification agent inlet pipe (106), the temperature of the dense phase zone is controlled at 700-1000°C, the gasification agents are introduced from the gasification agent inlet (102), the temperature of the dilute phase zone is controlled at 1000-1300°C, and the gas-solid mixture generated by the multi-stage staged fluidized bed gasifier (1) is separated from the center jet pipe (105) through a slagging pipe (104), and the separated solid ash is discharged through the slagging pipe (104); The waste heat recovery and reducing gas preparation step: high-temperature gasification gas is sent to a waste heat boiler (2) from the gasification agent outlet to recover sensible heat, cold water is introduced through a cold water inlet (203) to generate steam, and the steam produced by the waste heat boiler (2) is sent back to the distribution plate gasification agent inlet pipe (107), the center jet pipe (105), and the slagging pipe gasification agent inlet pipe (106) as a gasification agent through a steam outlet; The reducing reactor (3) reaction step: the hot boiler sends the biomass gasification gas to a first reducing gas inlet (306), a second reducing gas inlet (310), and a third reducing gas inlet (309) through a pipeline after being cooled, the biomass gasification gas is reacted in the reducing reactor (3) to generate a gas-solid mixture, the gas-solid mixture is subjected to primary gas-solid separation and particle instant backmixing through an internal cyclone separator (301), at the same time, a fine iron ore feeding port (304) receives fine iron ore powder materials, the iron ore powder is subjected to a reduction reaction with the reducing gas, and finally, metallized iron with a metallization rate of ≥95% is obtained, the metallized iron is sent to the inside of a product tank (4) from a product outlet (308), the internal temperature of the reducing reactor (3) is set to 500-700°C, the working pressure is set to 0.1-1.5 MPa, and the superficial gas velocity is set to 0.5-1.2 m / s; The material circulation and gas purification step: the gas-solid mixture is sent to an external cyclone separator (5) through a pipeline from a gas outlet (302) to be separated, the separated small solid particles enter a return device (7) and are returned to the reducing reactor (3) through a return inlet (305) to be circulated, and the reducing gas is sent to a water washing tower (6) through a pipeline from the external cyclone separator (5) to be purified.

7. The method of multi-stage staged biomass gasification coupled with iron ore fines reduction according to claim 6, characterized in that: The oxygen volume concentration of the gasification agents introduced into the distribution plate gasification agent inlet pipe (107), the center jet pipe (105), and the slagging pipe gasification agent inlet pipe (106) is 10-25%, 20-70%, and 0-25% respectively, and the gasification agents introduced into the gasification agent inlet (102) are pure oxygen.

8. The method of multi-stage staged biomass gasification coupled with iron ore fines reduction according to claim 6, characterized in that: The main component of the fine iron ore powder is Fe3O4, and the particle size range is 0-0.15 mm.

Images