Graded gasification system and graded gasification method of gasification raw material

Abstract

The disclosure provides a staged gasification system and method for gasifying raw materials, belonging to the technical field of gasification. The staged gasification system for gasifying raw materials comprises a fly ash circulating loop formed by a fluidized bed gasification reaction device, a dust removal unit and a high-temperature gasification reaction device connected in sequence. The fluidized bed gasification reaction device comprises a gasification furnace connected by a connecting section to a turbulent fluidization section and a transport section, so as to discharge the coarse coal gas and fly ash generated by the gasification reaction of the turbulent fluidization section from the gasification furnace. The fly ash discharged from the gasification furnace is captured by the dust removal unit to achieve gas-solid separation of the coarse coal gas and the fly ash. The high-temperature gasification reaction device is provided with a gasification agent air pipe and a fly ash air pipe connected to the dust removal unit, and the fly ash and the high-temperature coal gas and high-temperature ash generated by the high-temperature gasification reaction of the gasification agent are transported into the gasification furnace, so as to utilize the sensible heat of the high-temperature coal gas and high-temperature ash for gasification reaction in the fluidized bed gasification reaction.

Description

Technical Field

[0001] This disclosure belongs to the field of gasification technology, and particularly relates to a staged gasification system and a staged gasification method for gasification feedstock. Background Technology

[0002] Currently, staged gasification is used to classify and gasify materials of different particle sizes and gasification activities, thereby achieving higher carbon conversion rates and thermal conversion efficiencies. For example, related technologies incorporate high-temperature gasification reactors in the circulation loop of a circulating fluidized bed. The easily gasifiable portions of the feedstock are first gasified in the fluidized bed gasification reactor, followed by the high-temperature gasification reactor to gasify the finer-particle-size, low-volatile-content, and difficult-to-gasify fly ash. The high-temperature gasification products are then fed into the solid material circulation loop of the fluidized bed, and the sensible heat of these products is used for fluidized bed gasification, thus improving the carbon conversion rate and absorbing the fly ash generated during the fluidized bed gasification reaction.

[0003] However, due to the fine particle size, high concentration, insufficient momentum, and weak turbulence of the material in the circulation loop, the high-temperature gasification products generated by the high-temperature gasification reactor directly enter the circulation loop. Due to the high circulation ratio and fine circulating material in the circulation loop, slag easily forms at the high-temperature (1000-1200℃) nozzle of the fluidized bed. As a result, the high-temperature ash slag generated by the high-temperature gasification reactor solidifies before it can disperse due to the cooling of the circulating material. This leads to slag formation and wall adhesion problems on the furnace wall, separator, return feeder, etc., causing the staged gasification system to shut down. Summary of the Invention

[0004] To address the aforementioned technical problems, this disclosure provides a staged gasification system and method for gasification feedstock. By designing the structures of the fluidized bed gasification reactor and the high-temperature gasification reactor, the high-temperature coal gas and high-temperature ash generated from the high-temperature physicochemical reaction are directly transported into the gasifier through the top nozzle of the fluidized bed gasification reactor. This allows for the utilization of their sensible heat during the fluidized bed gasification reaction, improving carbon conversion while preventing the high-temperature ash from cooling, solidifying, and adhering to the walls. The technical solution provided by this disclosure is as follows.

[0005] As a first aspect of this disclosure, a staged gasification system for gasification feedstock is provided, comprising: a fluidized bed gasification reactor, a dust removal unit, and a high-temperature gasification reactor.

[0006] The fluidized bed gasification reactor includes a gasifier consisting of a turbulent fluidization section, a connecting section, and a transport section. The turbulent fluidization section and the transport section are connected by the connecting section to discharge crude gas and fly ash from the gasifier. The turbulent fluidization section includes, from bottom to top, a dense phase zone, a transition zone, and a dilute phase zone. A primary air inlet and a ash discharge port for discharging bottom ash are provided at the bottom of the gasifier. A gasification feedstock inlet is provided in the dilute phase zone, and a nozzle is provided at the top of the dilute phase zone.

[0007] The dust removal unit, located downstream of the fluidized bed gasification reactor, is used to collect the fly ash discharged from the gasifier to achieve gas-solid separation of crude gas and fly ash.

[0008] The high-temperature gasification reactor is located downstream of the dust removal unit. It is equipped with a gasifying agent duct, a fly ash duct connected to the dust removal unit, and a discharge port for discharging high-temperature coal gas and high-temperature ash. The discharge port is connected to the nozzle to form a fly ash circulation loop, so that the high-temperature coal gas and high-temperature ash generated by fly ash gasification can be injected into the gasifier through the nozzle to utilize the sensible heat of the high-temperature coal gas and high-temperature ash in the fluidized bed gasification reaction.

[0009] As a second aspect of this disclosure, a method for staged gasification of gasification feedstock is provided, executed by the aforementioned staged gasification system. This staged gasification method includes: gasifying the gasification feedstock in the turbulent fluidization section of the gasifier of a fluidized bed gasification reactor to produce crude coal gas, fly ash, unreacted solid materials, and bottom ash; allowing the crude coal gas and fly ash to enter a dust removal unit, where the fly ash is collected to achieve gas-solid separation of the crude coal gas and fly ash; conveying the fly ash to a high-temperature gasification reactor, where it is gasified with a gasifying agent to produce high-temperature coal gas and high-temperature ash; and injecting the high-temperature coal gas and high-temperature ash into the gasifier through nozzles located in the dilute phase zone at the top of the gasifier, where they come into contact with the turbulent gasification feedstock and unreacted solid materials under the impetus of the gas, so that the gasification feedstock and unreacted solid materials undergo fluidized bed gasification reaction using the sensible heat of the high-temperature coal gas and high-temperature ash, wherein the unreacted solid materials include semi-coke and circulating ash.

[0010] Based on the above technical solution, the staged gasification system and staged gasification method for gasification feedstock provided in this disclosure have at least one of the following beneficial effects:

[0011] (1) In the technical solution disclosed herein, a fluidized bed gasification reactor is used to gasify the easily gasifiable portion of the gasification feedstock, producing fly ash that is difficult to gasify, crude coal gas, unreacted solid materials, and bottom ash. Simultaneously, the intense turbulent crushing capacity within the gasifier is used to crush the high-temperature ash formed by the high-temperature gasification of fly ash into fine powder. By designing the structure of the fluidized bed gasification reactor and the high-temperature gasification reactor, a dust removal unit is used to collect the fly ash discharged from the gasifier to achieve gas-solid separation. The obtained fly ash is fed into the high-temperature gasification reactor, where the fly ash that is difficult to gasify undergoes a high-temperature enhanced gasification reaction to produce high-temperature coal gas and high-temperature ash, achieving higher carbon conversion rate, higher thermal efficiency, and lower oxygen consumption. The discharge port of the high-temperature gasification reactor is connected to the nozzle at the top of the gasifier in the fluidized bed gasification reactor. High-temperature coal gas and high-temperature ash are injected into the gasifier through the nozzle. The higher mass and heat transfer efficiency of the gasifier is used to recover the sensible heat of the high-temperature coal gas and high-temperature ash generated by the high-temperature gasification reactor and use it for fluidized bed gasification reaction to achieve higher cold coal gas efficiency. At the same time, the strong turbulent fluidization effect in the dense phase zone of the gasifier is used to quickly disperse the cooled ash and prevent it from slagging and affecting the stability of the gasification reactor operation.

[0012] (2) In the technical solution disclosed herein, a gasifier consisting of a turbulent fluidization section, a connecting section and a transport section is adopted, which can enhance the turning and / or mixing between gas and solid flows, destroy the gas-solid ring core structure in areas with high particle concentration and reaction temperature, strengthen the mass transfer, heat transfer and gasification reaction between gas and solid, and improve carbon conversion efficiency and pyrolysis volatiles. Attached Figure Description

[0013] Figure 1 This is a framework diagram of the staged gasification system for gasification feedstock in an embodiment of this disclosure;

[0014] Figure 2 This is a schematic diagram of the structure of the fluidized bed gasification reactor in the embodiments of this disclosure;

[0015] Figure 3 This is a schematic diagram of the high-temperature gasification reaction device in an embodiment of this disclosure;

[0016] Figure 4 This is a schematic diagram showing the connection between the connecting section and the transport section in an embodiment of this disclosure;

[0017] Figure 5 This is a schematic diagram of the secondary air duct layout structure;

[0018] Figure 6 This is a schematic diagram of the structure of a fluidized bed gasification reactor in another embodiment of this disclosure;

[0019] Figure 7 This is a schematic diagram of the high-temperature gasification reaction device in another embodiment of the present disclosure;

[0020] Figure 8 This is a schematic diagram of the air distribution structure at the bottom of the turbulent fluidization section in an embodiment of this disclosure.

[0021] [Attached image labels]

[0022] 1-Fluidized bed gasification reactor, 1-1-Gasifier, 1-2-Gas-solid separator, 1-3-Return feeder, 1-11-Turbulent fluidization section, 1-12-Connecting section, 1-13-Transportation section, 11-Primary air duct, 12-Slag discharge port, 13-Return feed port, 14-Nozzle, 15-Outlet of transport section, 16-Gasification feedstock inlet, 17-Connecting port, 18-Secondary primary air duct, 19-Tertiary primary air duct, 20-Secondary air duct, 21-Gasification product inlet, 22-Solid material outlet, 23-Gaseous material outlet, 31-Return feed inlet, 32-Return feed outlet;

[0023] 2- Waste heat recovery unit;

[0024] 3-Dust removal unit;

[0025] 4-High-temperature gasification reaction device, 41-Fly ash duct, 42-Gasifying agent duct, 43-Discharge port, 44-Second gasifying agent duct, 4-1-First stage gasification reactor with burner structure, 4-2-Second stage gasification reactor with burner structure;

[0026] A - Bottom ash cooling section, B - Waiting section, C - Supplementary fluidization section, D - Gasification feedstock, G - Crude gas, G1 - High-temperature gas, AS - Fly ash, F - Bottom ash, F1 - High-temperature ash, g1 - Primary air, g2 - Gasifying agent, g3 - Secondary air, g 1-1 -Level 1 wind, g 1-2 -Level 2 wind, g 1-3 - Level 3 wind, g 2-1 -First vaporizing agent, g 2-2 - Second gasifying agent. Detailed Implementation

[0027] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0028] Gasification is one of the core technologies for the clean and efficient utilization of coal, biomass, and carbon-containing solid waste, and it is the source for the development of coal chemical industry and biomass-based green methanol and other chemical industries. Current gasification technologies can be classified according to the gas-solid flow pattern into: fixed-bed gasification technology, fluidized-bed gasification technology, and entrained gasification technology. Fluidized-bed gasification technology uses a fluidized bed for the gasification reaction and employs solid-state slag discharge. It has advantages such as strong feedstock adaptability, environmental friendliness, no tar, phenolic water, or black water wastewater generation, high gasification intensity, and low investment. However, existing fluidized-bed gasification technologies are limited by low gasification temperatures and the tendency to generate large amounts of high-carbon fly ash, resulting in low carbon conversion. Fly ash accounts for 15%-25% of the feedstock, with a carbon content reaching 28%-80%. Although fluidized bed gasification has a high carbon conversion rate, it requires grinding the gasification feedstock into powder with a particle size of <100 micrometers and using high temperature to enhance the gasification reaction to increase the gasification intensity and achieve a higher carbon conversion rate. However, the pulverization cost is high, and the quenching of high-temperature gas will lead to a large consumption of water and the generation of a large amount of black water. In addition, the sensible heat of high-temperature gas and high-temperature ash is not effectively used for the gasification reaction.

[0029] Although related technologies classify and gasify materials of different particle sizes and gasification activities through grading, problems such as high-temperature ash agglomeration, wall adhesion, and low carbon conversion rates still exist. To address these issues, this disclosure provides a graded gasification system and method for gasification feedstock. By designing the structures of the fluidized bed gasification reactor and the high-temperature gasification reactor, slagging and wall adhesion are avoided in the graded gasification system, achieving higher carbon conversion and thermal efficiency.

[0030] Figure 1 This is a framework diagram of the staged gasification system for gasification feedstock in an embodiment of this disclosure. Figure 2 This is a schematic diagram of the structure of the fluidized bed gasification reactor in an embodiment of this disclosure. Figure 3 This is a schematic diagram of the high-temperature gasification reaction device in the embodiments of this disclosure.

[0031] like Figures 1-3 As shown, the present disclosure provides a staged gasification system for gasification feedstock, comprising: a fluidized bed gasification reactor 1, a dust removal unit 3, and a high-temperature gasification reactor 4.

[0032] The fluidized bed gasification reactor 1 includes a gasifier 1-1 consisting of a turbulent fluidization section 1-11, a connecting section 1-12, and a transport section 1-13. The turbulent fluidization section 1-11 and the transport section 1-13 are connected by the connecting section 1-12 to discharge the crude coal gas G and fly ash AS from the gasifier 1-1. The turbulent fluidization section 1-11 includes, from bottom to top, a dense phase zone, a transition zone, and a dilute phase zone. A primary air inlet 11 and a ash discharge port 12 for discharging bottom ash F are provided at the bottom of the gasifier 1-1. A gasification feedstock inlet 16 is provided in the dilute phase zone, and a nozzle 14 is provided at the top of the dilute phase zone.

[0033] The dust removal unit 3, located downstream of the fluidized bed gasification reactor 1, is used to collect the fly ash AS discharged from the gasifier 1-1 to achieve gas-solid separation of the crude coal gas G and the fly ash AS.

[0034] The high-temperature gasification reactor 4 is located downstream of the dust removal unit 3. It is equipped with a gasifying agent duct 42, a fly ash duct 41 connected to the dust removal unit 3, and a discharge port 43 for discharging high-temperature coal gas G1 and high-temperature ash residue F1. The discharge port 43 is connected to the nozzle 14 to form a circulation loop for fly ash AS, so that the high-temperature coal gas G1 and high-temperature ash residue F1 generated by the gasification of fly ash AS can be injected into the gasifier 1-1 through the nozzle 14, so as to utilize the sensible heat of high-temperature coal gas G1 and high-temperature ash residue F1 in the fluidized bed gasification reaction.

[0035] Through the above design, the easily gasifiable portion of the gasification feedstock D is gasified using a fluidized bed gasification reactor 1, producing fly ash AS (which is difficult to gasify), crude gas G, unreacted solid materials, and bottom ash. Simultaneously, the intense turbulent crushing capacity within the gasifier 1-1 breaks the high-temperature ash residue F1 generated from the high-temperature gasification of fly ash AS into fine powder. By designing the structures of the fluidized bed gasification reactor 1 and the high-temperature gasification reactor 4, gas-solid separation is achieved by using a dust removal unit 3 to collect fly ash AS. The obtained fly ash AS is then fed into the high-temperature gasification reactor 4, where the difficult-to-gasify fly ash AS is gasified using a high-temperature enhanced gasification reaction, producing high-temperature gas G1 and high-temperature ash residue F1, achieving higher carbon conversion rate, higher thermal efficiency, and lower oxygen consumption. The discharge port 43 of the high-temperature gasification reactor 4 is connected to the nozzle 14 at the top of the gasifier 1-1 in the fluidized bed gasification reactor 1. High-temperature gas G1 and high-temperature ash F1 are injected into the gasifier 1-1 through the nozzle 14. The sensible heat of the high-temperature gas G1 and high-temperature ash F1 generated by the high-temperature gasification reactor 4 is recovered by utilizing the higher mass and heat transfer efficiency of the gasifier 1-1 and used for fluidized bed gasification reaction to achieve higher cold gas efficiency. At the same time, the strong turbulent fluidization effect in the dense phase zone of the gasifier 1-1 is used to quickly disperse the cooled high-temperature ash F1, avoiding slagging and affecting the stability of the gasification reactor operation.

[0036] Specifically, continue as Figure 2As shown, the gasifier 1-1 is a fluidized bed, and its turbulent fluidization section 1-11 consists of a truncated cone (larger at the top and smaller at the bottom) and a cylinder at the top of the cone. This section serves as the main gasification reaction zone for the gasification feedstock D. The inclination angle of the truncated cone at the bottom of the turbulent fluidization section 1-11 is 68°-85°. At the bottom of the gasifier 1-1, there is a ash discharge port 12 for discharging bottom ash F, a primary air inlet 11 for supplying primary air g1, and an air distribution unit for supplying primary air g1 into the furnace of the gasifier 1-1. This air distribution unit includes an air cap, an air distribution plate, and an air chamber. Furthermore, the turbulent fluidization section 1-11 can be divided into a dense phase zone, a transition zone, and a dilute phase zone from bottom to top. A return port 13 and a connection port 17 for connecting the turbulent fluidization section 1-11 to the connecting section 1-12 are provided in the transition zone. The angle between the return port 13 and the connection port 17 is 90°-180°. The height of the return port 13 from the air distribution plate is 0.5m-3.5m, and the height difference between the connection port 17 and the return port 13 is 0.2m-5.0m. A nozzle 14 is provided at the top of the dilute phase zone of the gasifier. This nozzle 14 is connected to the discharge port 43 of the high-temperature gasification reactor 4 to inject the high-temperature gas G1 and high-temperature ash F1 (≥1000℃) generated by the high-temperature gasification reactor 4 into the gasifier 1-1. The dense phase zone of the turbulent fluidization section 1-11 has a high particle concentration, more intense turbulent fluidization, and a large internal circulation volume. Utilizing the high heat and mass transfer efficiency of gasifier 1-1 (i.e., fluidized bed), the high-temperature gas G1 and high-temperature ash F1 generated by the high-temperature gasification reaction fall into the dense phase zone of the turbulent fluidization section 1-11 under the action of gas driving force, and come into contact with the turbulent solid particles in the dense phase zone. Under the intense turbulent fluidization, the sensible heat of the high-temperature gas G1 and high-temperature ash F1 is transferred to the solid particles in the dense phase zone, which is used for the gasification reaction of the gasification feedstock D and primary air g1 in the turbulent fluidization section 1-11, producing gaseous material containing crude gas G and fly ash AS, bottom ash F, and unreacted solid material (including semi-coke and circulating ash). This can significantly reduce the oxygen consumption of the staged gasification system. At the same time, the turbulent action is used to quickly disperse and cool the high-temperature ash F1, effectively avoiding the problem of slagging caused by the high-temperature ash F1 agglomerating. The connecting section 1-12 and the conveying section 1-13 are connected to the turbulent fluidization section 1-11 through the connection port 17. The crude coal gas produced by the gasification reaction in the turbulent fluidization section 1-11, as well as the entrained fly ash and some unreacted solid materials, are carried out of the turbulent fluidization section 1-11. This disrupts the gas-solid ring core structure in the turbulent fluidization section 1-11 (gas rises in the central region (core), while solid particles descend along the side walls (ring)). This prevents the high-temperature ash slag F1 from solidifying during its descent and forming slag and adhering to the wall of the gasifier 1-1. At the same time, it enhances gas-solid contact and improves the gasification reaction efficiency.By designing the angle and height difference between the connection port 17 and the return port 13, the gasification reaction in the gasifier 1-1 is ensured to proceed smoothly while balancing the pressure inside the gasifier 1-1. This reduces the amount of solid particles (gasification feedstock D and solid materials) in the furnace of the gasifier 1-1 entering the connection section 1-12 through the connection port 17 under the entrainment of the crude gas G, and also reduces the amount of solid particles in the furnace of the gasifier 1-1 entering the gas-solid separator 1-2 through the return port 13, which could lead to the failure of the gas-solid separator 1-2 (such as a cyclone gas-solid separator).

[0037] Continue as Figure 2 As shown, a blind path is provided at the end of connecting section 1-12 away from the connection port. The angle between the centerline of connecting section 1-12 and the horizontal line is 30°-70°, and the length of the blind path is 0.2-1.25 times the diameter of connecting section 1-12. In this embodiment, the crude coal gas G generated in the lower gasification reaction zone of the gasifier 1-1 furnace will carry fly ash AS and some unreacted solid materials (i.e., carbon-containing solid fuel) from the transition zone and / or dilute phase zone sidewall of turbulent fluidization section 1-11 through connection port 17 and connecting section 1-12 into transport section 1-13. By providing a blind path at the end of connecting section 1-12, the blind path can provide a buffer for the large-angle deflection of gas and solid materials, and can also enhance the mixing and distribution between gas and solid. The connecting section 1-12 is designed with an upwardly inclined structure and its upward inclination angle is controlled to avoid the segregation of solid particles in connecting section 1-12 and their sinking to the bottom, which would lead to coking in connecting section 1-12. In addition, the combined effect of the upward-sloping structure and the tactile paving can enhance the mass and heat transfer between gas and solid.

[0038] Figure 4 This is a schematic diagram illustrating the connection between the connecting section and the transport section in an embodiment of this disclosure. Figure 5 This is a schematic diagram of the secondary air duct layout.

[0039] Furthermore, such as Figure 2 , Figures 4-5As shown, the connection between connecting section 1-12 and transport section 1-13 extends along the gas direction. A secondary air duct 20 for secondary air g3 to enter is provided in transport section 1-13 along the gas extension direction. There are multiple secondary air ducts 20, which are located on the same horizontal plane and arranged tangentially around transport section 1-13. The angle α between the axial direction and the horizontal direction for secondary air g3 entering transport section 1-13 is ±30°. The secondary air ducts 20 are located 0.1m to 1m away from the connection between transport section 1-13 and connecting section 1-12. The tangential diameter d of the secondary air duct 20 is between 0.5 times the diameter of connecting section 1-12 and 0.80 times the diameter of the cross section at the center line of the nozzle of secondary air duct 20. In this embodiment, the crude coal gas G, carrying fly ash AS and some unreacted solid materials, enters the conveying section 1-13 via the connecting section 1-12. As the diameter of the connection between the connecting section 1-12 and the conveying section 1-13 gradually increases, the gas velocity gradually decreases. Solid particles experience backflow and remixing at the connection between the connecting section 1-12 and the conveying section 1-13, resulting in an increased particle concentration. At this time, secondary air g3 is introduced into the conveying section 1-13 in a tangential circular manner. This changes the gas-solid ring core structure within the conveying section 1-13, causing the gas and solid to swirl upwards. This enhances the mixing, mass transfer, heat transfer, and reaction between the secondary air g3 and the carbon-containing solid fuel, improves the carbon conversion rate and the cracking of pyrolysis volatiles within the conveying section 1-13, reduces the tar content in the crude coal gas G, and further removes large molecular compounds from the crude coal gas G, thus achieving the conversion of organic impurities in the crude coal gas G. Thus, by utilizing the gasifier 1-1 furnace chamber, which consists of turbulent fluidization section 1-11, connecting section 1-12, and transport section 1-13, the turning and mixing between gas and solid flows are increased, the mass transfer and reaction between gas and solid are enhanced, and oxygen is added in the area with high particle concentration, thereby enhancing the gasification reaction and increasing the carbon conversion rate by 0.5%-2%.

[0040] Specifically, continue as Figure 2 As shown, the fluidized bed gasification reactor 1 also includes: a gas-solid separator 1-2 and a return feeder 1-3.

[0041] One end of the gas-solid separator 1-2 is connected to the conveying section 1-13, and the other end is connected to the return feeder 1-3. Specifically, the gas-solid separator 1-2 is equipped with a gasification product inlet 21 connected to the outlet 15 of the conveying section 1-13, a gas material outlet 23 for discharging crude coal gas G and fly ash AS, and a solid material outlet 22 for discharging unreacted solid material. This allows the gasification products from the gasification reaction of crude coal gas G, fly ash AS, and unreacted solid material with secondary air g3 to be conveyed to the gas-solid separator 1-2 for gas-solid separation, yielding solid material, crude coal gas G, and fly ash AS. The unreacted solid material includes semi-coke and circulating ash, which exits the gas-solid separator 1-2 through the solid material outlet 22; the crude coal gas G and fly ash AS exit the gas-solid separator 1-2 through the gas material outlet 23. Furthermore, the gas-solid separator 1-2 can be a high-efficiency cyclone separator with a separation efficiency ≥99%, and other high-efficiency gas-solid separators can also be used.

[0042] The return feeder 1-3, located downstream of the gas-solid separator 1-2, is equipped with a return inlet 31 for unreacted solid material to enter and a return outlet 32 ​​for discharging unreacted solid material. The return inlet 31 of the return feeder 1-3 is connected to the solid material outlet 22 of the gas-solid separator 1-2, and the return outlet 32 ​​of the return feeder 1-3 is connected to the return port 13 located in the transition zone of the gasifier 1-1. This allows the return feeder 1-3 to return unreacted solid material to the gasifier 1-1 for gasification, while preventing cross-contamination and ensuring smooth return. Furthermore, the return feeder 1-3 is a non-mechanical return feeder, such as any one of a U-shaped, J-shaped, N-shaped, or L-shaped return feeder, or a jet conveyor; a U-shaped return feeder is preferred.

[0043] As an alternative, a connection port can be provided at the top of the dilute phase zone of gasifier 1-1 to connect the central axis of connecting section 1-12 and turbulent fluidization section 1-11, as shown in the specific structure. Figure 6 As shown.

[0044] Figure 6 This is a schematic diagram of the structure of a fluidized bed gasification reactor in another embodiment of this disclosure.

[0045] like Figure 6 As shown, in another embodiment, the fluidized bed gasification reactor 1 has the same features as described above. Figures 1-4The structure and reaction process are identical, with the only difference being that a connection port is provided at the top of the dilute phase zone of gasifier 1-1 to connect the center of the top of connecting section 1-12 and turbulent fluidization section 1-11. Nozzle 14 is located at the top of gasifier 1-1, and the angle between the centerline of nozzle 14 and the centerline of turbulent fluidization section 1-11 is 10°-45°. Through the aforementioned structural design of connecting section 1-12 and transport section 1-13, the gas-solid ring core structure can be altered, resulting in a more uniform gas-solid distribution. Simultaneously, oxygen is introduced into areas with higher particle concentrations to enhance the gasification reaction.

[0046] In the embodiments of this disclosure, the structure of the fluidized bed gasification reactor 1 is designed according to the above embodiments, so as to realize the use of the high mass transfer and heat transfer of the fluidized bed gasifier to cool the high-temperature ash slag F1 generated by the high-temperature gasification reactor 4, avoiding the problem of a large amount of black water caused by water quenching to cool the high-temperature ash slag F1; at the same time, while cooling the high-temperature ash slag F1 and high-temperature coal gas G1, the fluidized bed recovers its sensible heat and uses it for the fluidized bed gasification reaction, reducing the combustion share of the gasification feedstock D, significantly improving the utilization effect of cold coal gas, and reducing oxygen consumption.

[0047] According to embodiments of this disclosure, continuing as follows Figure 1 As shown, the above-mentioned staged gasification system also includes: a waste heat recovery unit 2, located downstream of the fluidized bed gasification reactor 1 and upstream of the dust removal unit 3, used to recover the heat of the crude coal gas G and fly ash AS, and reduce the temperature of the crude coal gas G and fly ash AS to 150℃-350℃.

[0048] According to embodiments of this disclosure, when the high-temperature gasification reactor is a single-stage gasification reactor with a burner assembly, it has the following characteristics: Figure 3The structure shown is as follows. The gasification reactor with burner assembly includes a cylindrical body and a burner assembly located at the top of the cylindrical body. The burner assembly consists of a fly ash duct 41 and a gasifying agent duct 42, wherein the fly ash duct 41 is located on the center line of the high-temperature gasification reactor 4, and the gasifying agent duct 42 is arranged around the fly ash duct 41. In this embodiment, fly ash AS from the dust removal unit 3 enters the burner assembly via the fly ash duct 41 and the gasifying agent g2 via the gasifying agent duct 42, and undergoes a high-temperature gasification reaction within the cylindrical body under the action of the burner assembly, producing high-temperature gas G1 and high-temperature ash F1. Arranging the gasifying agent duct 42 around the fly ash duct 41 facilitates the control of fly ash AS and gasifying agent g2, and also enhances mixing. Considering the poor gasification activity and long flame of fly ash AS, and to ensure a stable outflow of high-temperature ash F1 from the high-temperature gasification reactor 4, the height-to-diameter ratio of the high-temperature gasification reactor 4 is controlled between 2 and 3.5. After the high-temperature gasification reaction is completed, the generated high-temperature gas G1 and high-temperature ash F1 are discharged from the high-temperature gasification reaction device 4 through the ash discharge port 43, and enter the furnace of the gasifier 1-1 through the nozzle 14 set at the top of the turbulent fluidization section 1-11.

[0049] As an alternative, the high-temperature gasification reactor 4 can be a two-stage gasification reactor with burner components, the specific structure of which is as follows: Figure 7 As shown.

[0050] Figure 7 This is a schematic diagram of the structure of a high-temperature gasification reaction device in another embodiment of this disclosure.

[0051] like Figure 7As shown, in the case where the high-temperature gasification reactor 4 is a two-stage gasification reactor with burner components: the two-stage gasification reactors with burner components have the same structure. The slag discharge port of the first-stage gasification reactor 4-1 with burner components serves as the inlet of the fly ash duct of the second-stage gasification reactor 4-2 with burner components. The second-stage gasification reactor 4-2 also has a second gasifying agent duct 44, which is arranged around the fly ash duct. The first-stage gasification reactor 4-1 with burner components performs the gasification reaction in the non-slag zone, producing crude high-temperature coal gas and non-slag high-temperature ash. The second-stage gasification reactor 4-2 with burner components performs the gasification reaction in the slag zone, gasifying the carbon in the non-slag high-temperature ash and the crude high-temperature coal gas to produce high-temperature coal gas G1 and high-temperature ash F1. Specifically, the first-stage gasification reactor 4-1 with burner components includes: a first cylinder and a first burner component located at the top of the first cylinder. The first burner assembly consists of a fly ash duct 41 and a gasifying agent duct 42. The fly ash duct 41 is located on the center line of the high-temperature gasification reaction device 4, and the gasifying agent duct 42 is arranged around the fly ash duct 41 so that the fly ash AS from the dust removal unit 3 can directly enter the first cylinder through the fly ash duct 41 and react with the first gasifying agent g entering through the gasification duct 42. 2-1 Under the first burner organization, a non-molten slag high-temperature gasification reaction is carried out in the first-stage gasification reactor 4-1 with burner organization. The resulting crude high-temperature coal gas and non-molten slag high-temperature ash are discharged through the discharge port of the first-stage gasification reactor 4-1 with burner organization and enter the fly ash duct of the second-stage gasification reactor 4-2 with burner organization. The second-stage gasification reactor 4-2 with burner organization includes: a second cylinder and a second burner organization located at the top of the second cylinder, wherein the second gasifying agent duct 44 is arranged around the fly ash duct so that the non-molten slag high-temperature ash and crude high-temperature coal gas react with the second gasifying agent g. 2-2 The molten slag undergoes a high-temperature gasification reaction in the second-stage gasification reactor 4-2 with burners, producing reformed high-temperature coal gas G1 and high-temperature ash F1, which are discharged through the discharge port 43 of the second-stage gasification reactor 4-2 with burners.

[0052] Furthermore, in the above Figures 1-7 In this embodiment, water atomizing nozzles are arranged around the nozzle 14 at the top of the turbulent fluidization section 1-11. The water sprayed from the water atomizing nozzles is used to quench the high-temperature coal gas G1 and high-temperature ash F1 sprayed from the nozzle 14, so as to rapidly reduce the high-temperature ash F1 to below the softening temperature of the ash. The water sprayed from the water atomizing nozzles can be tap water, plant wastewater, gasification condensate, etc.

[0053] Figure 8 This is a schematic diagram of the air distribution structure at the bottom of the turbulent fluidization section in an embodiment of this disclosure.

[0054] like Figure 8As shown, the dense phase region of the turbulent fluidization section 1-11 includes, from bottom to top: bottom ash cooling section A, throat section B, and supplementary fluidization section C.

[0055] The bottom of the bottom ash cooling section A is equipped with a primary air supply unit. 1-1 The primary air inlet 11 has a slag discharge port 12 on its side wall for discharging bottom slag F. The primary air g... 1-1 As a cooling medium, the bottom ash F is cooled, and the waste heat of the bottom ash F can be further recovered and used for gasification reaction.

[0056] The side wall of throat section B is equipped with a secondary primary air supply unit. 1-2 The secondary primary air duct 18 enters, and the height-to-diameter ratio H of the throat section B is 0.5-2. Throat section B is used for air classification of the bottom ash F entering this area to separate and fluidize the coarse and fine bottom ash. For the fine bottom ash, further classification is performed in the secondary primary air duct g. 1-2 Driven by the airflow, the material moves upwards to enter the supplementary fluidization section C for further fluidization. For coarse bottom ash, it moves downwards under its own gravity to enter the bottom ash cooling section A for cooling, and then exits the gasifier 1-1. To ensure sufficient air classification time in the throat section B, the height-to-diameter ratio of the throat section B is controlled at 0.5-2.

[0057] The supplementary fluidization section C is equipped with multiple tertiary primary air ducts 19, which are located on the same horizontal plane. The angle β between the centerline of each duct and the horizontal line is 8°-30°, and they are arranged in an upwardly inclined tangential circle around the supplementary fluidization section C. The diameter of this tangential circle is 0.5-0.85 times the diameter of the throat section B and the diameter of the horizontal plane where the ducts 19 are located. The distance between each duct 19 and the top of the throat section B is 0.5m-3m. In this embodiment, by setting multiple tertiary primary air ducts 19 in the supplementary fluidization section C and arranging them upwardly, it is convenient for the material (such as fine bottom ash) in the supplementary fluidization section C to move upward, so that the bottom ash and oxygen are mixed evenly, and the utilization rate of carbon in the bottom ash is improved.

[0058] Furthermore, in order to rapidly cool the bottom ash F, a water spray physicochemical unit can be installed in the bottom ash cooling section A to cool the bottom ash F using the phase change heat of water.

[0059] As a second aspect of this disclosure, a staged gasification method is provided, executed by the aforementioned staged gasification system for gasification feedstock, comprising: gasifying the gasification feedstock D in the turbulent fluidization section 1-11 of the gasifier 1-1 of the fluidized bed gasification reactor 1 to produce crude coal gas G, fly ash AS, unreacted solid materials, and bottom ash F; allowing the crude coal gas G and fly ash AS to enter a dust removal unit 3, whereby the dust removal unit 3 collects the fly ash AS to achieve gas-solid separation of the crude coal gas G and fly ash AS; and conveying the fly ash AS to a high-temperature gasification reactor. Inside device 4, gasifying agent g2 is used to generate high-temperature coal gas G1 and high-temperature ash residue F1. The high-temperature coal gas G1 and high-temperature ash residue F1 are injected into gasifier 1-1 through nozzle 14 set in the dilute phase zone at the top of gasifier 1-1. Under the action of gas, they come into contact with the turbulent gasification feedstock D and unreacted solid materials, so that the gasification feedstock D and unreacted solid materials can undergo fluidized bed gasification reaction using the sensible heat of high-temperature coal gas G1 and high-temperature ash residue F1. The unreacted solid materials include semi-coke and circulating ash.

[0060] In embodiments of this disclosure, such as Figure 1As shown, the gasification feedstock D and primary air g1 undergo a fluidized bed gasification reaction in the gasifier 1-1 of the fluidized bed gasification reactor 1. The resulting crude coal gas G and fly ash AS are discharged from the fluidized bed gasification reactor 1 and enter the dust removal unit 3. The dust removal unit 3 collects the fly ash AS discharged from the gasifier 1-1, achieving gas-solid separation of crude coal gas G and fly ash AS. The obtained crude coal gas G can be fed into downstream units for application. The fly ash AS collected by the dust removal system 3 is used as raw material in the high-temperature gasification reactor 4 to undergo a high-temperature gasification reaction with the gasifying agent g2. The high-temperature coal gas G1 and high-temperature ash F1 generated by the reaction are injected into the gasifier 1-1 of the fluidized bed gasification reactor 1 through the nozzle 14 set at the top of the gasifier 1-1. They are mixed with the gas and solid in the fluidized bed gasifier 1-1 and dispersed by the strong turbulence in the dense phase zone of the gasifier 1-1 to prevent the high-temperature ash from cooling and solidifying and forming slag. At the same time, the sensible heat of the high-temperature coal gas G1 and high-temperature ash F1 is transferred into the gasifier 1-1 for the fluidized bed gasification reaction. The cooled high-temperature ash F1 becomes the bottom ash F of the gasifier 1-1 and is discharged from the bottom of the furnace. Through the raw material classification gasification process, the fluidized bed gasification reactor 1 and the high-temperature gasification reactor 4 are coupled according to the gasification difficulty of the gasification raw material D to classify the gasification reaction. Utilizing the high turbulent crushing capacity and mass and heat transfer efficiency of the fluidized bed, the easily gasified feedstock D completes the fluidized bed gasification reaction within the fluidized bed gasification reactor 1. Simultaneously, the turbulent crushing capacity of the fluidized bed breaks down the difficult-to-gasify fly ash AS into powder, which is then collected by the dust removal unit 3. The high-temperature reaction in the high-temperature gasification reactor 4 gasifies the fine-particle-size, difficult-to-gasify powder (fly ash AS) to generate high-temperature gas G1 and high-temperature ash residue F1, which are then introduced into the fluidized bed. The turbulent solid material within the fluidized bed disperses and cools the high-temperature ash residue F1. The high heat transfer efficiency of the fluidized bed transfers the heat from the high-temperature gas G1 and high-temperature ash residue F1 to the gasification feedstock D, unreacted solid material, and primary air g1 within the fluidized bed for the fluidized bed gasification reaction, thereby improving the thermal efficiency and carbon conversion rate of the fluidized bed gasification reactor 1.

[0061] According to embodiments of this disclosure, the gasification share of the fluidized bed (i.e., gasifier 1-1) accounts for 55-85% of the total gasification volume (including fluidized bed gasification reactor 1 and high-temperature gasification reactor 4), wherein the gasification share is the percentage of the weight of the material gasified by the fluidized bed to the total weight of the material entering the staged gasification system.

[0062] According to embodiments of this disclosure, the apparent fluidization velocity at the bottom (dense phase region) of the turbulent fluidization section 1-11 is 2.5 m / s-6 m / s, and the apparent velocity in the dilute phase region is 0.8-2 m / s. Through the furnace structure and air distribution (primary and secondary air) structure of the gasifier 1-1, a bottom fluidized bed gasification reaction zone and an upper swirl transport bed gasification reaction zone are constructed in the fluidized bed gasification reactor. The fluidization velocity in the bottom fluidized bed gasification reaction zone decreases axially upwards, ensuring sufficient fluidization of the solid material at the bottom of the gasifier 1-1 furnace, while also providing strong material diffusion capacity and heat and mass transfer rates, and ensuring a large amount of internal circulation. The lower apparent fluidization velocity in the dilute phase region reduces the entrainment capacity of the crude gas G, preventing the high-viscosity, high-temperature ash slag F1 from being entrained into the connecting section 1-12 and causing coking and wall adhesion phenomena in the connecting section 1-12, conveying section 1-13, gas-solid separator 1-2, and return feeder 1-3. It also lowers the temperature at the top of the turbulent fluidization section 1-11 in the gasifier 1-1 furnace, cooling the high-temperature ash slag F1 ejected from the top nozzle 14 of the gasifier 1-1. When it reaches the bottom of the gasifier 1-1 (i.e., the fluidized bed surface), it avoids the formation of large amounts of carbon-coated solid material and effectively prevents the high-temperature ash slag F1 from agglomerating into large slag lumps. The turbulent gas-solid flow field constructed in the bottom fluidized bed gasification reaction zone allows the high-viscosity, high-temperature ash slag F1 coming down from the top of the gasifier 1-1 to be rapidly dispersed, cooled, and reacted under the turbulent action of full fluidization and strong internal circulation. In other words, the sensible heat of the high-temperature ash slag F1 is transferred to the gasified solid material and gasification feedstock D in the fluidized bed, while the high-viscosity high-temperature ash slag F1 is cooled, dispersed and solidified, thus avoiding slagging.

[0063] According to the embodiments of this disclosure, the gasification temperature of the fluidized bed gasification reactor 1 is 850℃~(ST-150℃, where ST is the softening temperature of the raw material ash). In order to maintain stable fluidization and stable gasification temperature of the fluidized bed and avoid slagging and local overheating, primary air g1 is introduced from the bottom of the furnace of gasifier 1-1. This area is the dense phase zone of gasifier 1-1, with higher particle concentration and temperature. In order to achieve sufficient fluidization while avoiding slagging, the oxygen concentration of primary air g1 is set to 15%-45%. The turbulent fluidization section 1-11 of gasifier 1-1 is the main reaction area of ​​gasification, and the proportion of primary air g1 in the total amount of gasifying agent is 50%-75%.

[0064] According to the embodiments of this disclosure, in order to disperse the high-temperature ash slag F1 generated by the high-temperature gasification reactor 4 and avoid it from sticking to the wall, the apparent wind speed of the high-temperature ash slag F1 ejected from the top nozzle 14 of the gasifier 1-1 is 3m / s-10m / s.

[0065] According to embodiments of this disclosure, the staged gasification system further includes: a waste heat recovery unit 2, located downstream of the fluidized bed gasification reactor 1 and upstream of the dust removal unit 3. The staged gasification method of this disclosure further includes: utilizing the waste heat recovery unit 2 to recover heat from the crude gas G and fly ash AS, thereby reducing the temperature of the crude gas G and fly ash AS to 350-150°C.

[0066] According to embodiments of this disclosure, connecting section 1-12 and conveying section 1-13 constitute the upper cyclone conveying bed gasification reaction zone. In the staged gasification method of this disclosure, before entering the waste heat recovery unit 2, the crude gas G and fly ash AS are as follows: after being discharged from the gasifier through connecting section 1-12 and conveying section 1-13, the crude gas G, entrained fly ash AS, and some unreacted solid materials enter the gas-solid separator 1-2 for gas-solid separation, resulting in crude gas G, fly ash AS, and unreacted solid materials; wherein, the unreacted solid materials are returned to the gasifier 1-1 via return feeder 1-3 to participate in the gasification reaction, while the crude gas G and fly ash AS enter the waste heat recovery unit 2.

[0067] According to embodiments of this disclosure, in the staged gasification method of this disclosure, crude coal gas G, entrained fly ash AS, and some unreacted solid materials are discharged from gasifier 1-1 through connecting section 1-12 and conveying section 1-13. This includes: crude coal gas G, entrained fly ash AS, and some unreacted solid materials enter the connecting section 1-12 through the connecting port 17 provided on the side wall of the transition zone of gasifier 1-1; the blind channel provided in the connecting section 1-12 is used to enhance the mixing and distribution between gas and solid materials; after uniform mixing, it enters the conveying section 1-13; secondary air g3 is introduced into the conveying section 1-13 to enhance the mixing of secondary air g3 with crude coal gas G, entrained fly ash AS, and some unreacted solid materials and to carry out gasification reaction, thereby improving carbon conversion rate and pyrolysis volatilization decomposition. The connecting section 1-12 is connected to the sidewall of the turbulent fluidization section 1-11 and is equipped with a blind channel to change the direction of gas-solid flow, thereby disrupting the gas-solid ring core structure. Through the buffering and reorganization of the blind channel, the gas-solid distribution becomes more uniform, thereby enhancing the gasification reaction.

[0068] As an alternative, in the staged gasification method disclosed herein, the crude gas G, along with the entrained fly ash AS and some unreacted solid materials, is discharged from the gasifier 1-1 through the connecting section 1-12 and the conveying section 1-13. This includes: the crude gas G, along with the entrained fly ash AS and some unreacted solid materials, enters the connecting section 1-12 and the conveying section 1-13 through the connecting port set at the top of the gasifier 1-1; secondary air g3 is introduced into the conveying section 1-13 to enhance the mixing of the secondary air g3 with the crude gas G, the entrained fly ash AS, and some unreacted solid materials and to carry out the gasification reaction, which can also improve the carbon conversion rate and pyrolysis volatilization decomposition.

[0069] Furthermore, the apparent fluidization velocity of connecting section 1-12 is 8 m / s to 20 m / s to prevent unreacted solid materials and fly ash AS from segregating and settling to the bottom, leading to coking. This apparent fluidization velocity also enhances mass and heat transfer between gas and solid. The apparent fluidization velocity of transport section 1-13 is 1.5 m / s to 10 m / s to prolong the gasification reaction between unreacted solid materials and secondary air g3, converting carbon in the unreacted solid materials into crude gas G and fly ash AS. This also reduces tar production in crude gas G and further removes large molecular compounds from crude gas G, achieving the conversion of organic impurities in crude gas G. Even further, the secondary air g3 is all on the same horizontal plane and enters transport section 1-13 in a tangential circular manner, causing the solid materials flowing down the sidewalls to swirl and fluidize towards the center. The secondary air duct 20 nozzle has a flow velocity of 45m / s-100m / s. This high-speed injection of secondary air g3 into the gasification reaction zone of transport sections 1-13 enhances the diffusion of secondary air g3 and temperature, as well as the gasification reaction, while preventing slagging. Furthermore, the oxygen concentration in the secondary air g3 is 21%-60% to ensure complete gasification.

[0070] According to embodiments of this disclosure, in the staged gasification method of this disclosure, when the high-temperature gasification reactor 4 is a single-stage gasification reactor with a burner, the gasification of fly ash AS to produce high-temperature gas G1 and high-temperature ash F1 includes: fly ash AS entering the burner through fly ash duct 41 and gasifying agent g2 entering the burner through gasifying agent duct 42, and undergoing a gasification reaction in the cylinder under the action of the burner to produce high-temperature gas G1 and high-temperature ash F1. The gasification reaction temperature in the high-temperature gasification reactor 4 is FT (ash fluidization temperature) + (150~200℃); the gasifying agent g2 is selected from any one of a mixture of oxygen and water vapor, carbon dioxide, a mixture of air and water vapor, or a mixture of air and carbon dioxide; the oxygen concentration in the gasifying agent g2 is 21%-100%, thereby ensuring that the fly ash AS reacts completely in the high-temperature gasification reactor 4.

[0071] As an alternative, in the staged gasification method disclosed herein, when the high-temperature gasification reactor 4 is a two-stage gasification reactor with burner components, the gasification of fly ash AS to produce high-temperature gas G1 and high-temperature ash residue F1 includes: fly ash AS and a first gasifying agent g 2-1 The fly ash duct 41 and gasifying agent duct 42 of the first gasification reactor 4-1 with burner structure enter the first burner structure. Under the action of the first burner structure, a gasification reaction occurs in the first cylinder, producing crude high-temperature coal gas and non-molten slag high-temperature ash, wherein the first gasifying agent g 2-1The gas is selected from any one of the following: a mixture of oxygen and water vapor, carbon dioxide, a mixture of air and water vapor, or a mixture of air and carbon dioxide; the oxygen concentration in gasifying agent g2 is 21%-100%; the gasification reaction temperature of the non-molten slag in the first-stage gasification reactor 4-1 with burner structure is 50-100℃ below the softening temperature (ST) of the ash. The high-temperature ash from the non-molten slag and the coarse high-temperature gas are discharged into the fly ash duct of the second-stage gasification reactor 4-2 with burner structure, and then mix with the second gasifying agent g2 entering through the second gasifying agent duct 44. 2-2 Under the action of the second burner, a gasification reaction takes place in the second cylinder to gasify the carbon and crude high-temperature coal gas in the non-molten slag high-temperature ash, producing high-temperature coal gas G1 and high-temperature ash F1; wherein, the gasification reaction temperature of the molten slag in the second stage gasification reactor 4-2 with the burner is FT (ash fluidization temperature) + (150~200℃); the second gasifying agent g 2-2 The gas is selected from any one of the following: a mixture of oxygen and water vapor, carbon dioxide, a mixture of air and water vapor, air and carbon dioxide, or a mixture of oxygen and carbon dioxide; the oxygen concentration in the gasifying agent g2 is 21%-70%.

[0072] According to embodiments of this disclosure, the staged gasification method in any of the above embodiments further includes: arranging water atomizing nozzles around the nozzle 14, and using the water sprayed from the water atomizing nozzles to quench the high-temperature coal gas G1 and high-temperature ash F1 sprayed from the nozzle 14.

[0073] According to the embodiments of this disclosure, the air distribution in the dense phase zone of the turbulent fluidization section 1-11 can be divided into three levels, namely, the dense phase zone from bottom to top includes: bottom ash cooling section A, throat section B and supplementary fluidization section C, and primary air is introduced into the aforementioned areas respectively.

[0074] Specifically, primary air g is introduced into the bottom ash cooling section A. 1-1 Level 1 wind 1-1 As a cooling medium, it lowers the temperature of the bottom ash F. Among them, the primary air g (stage 1) 1-1 The fluidized bed is selected from at least one of saturated water vapor, oxygen, and carbon dioxide, with an oxygen concentration ≤15%. The apparent fluidization velocity of the bottom ash cooling section A is 0.1-0.5 m / s. Secondary primary air is introduced into the throat section B. 1-2 Utilizing secondary primary wind g 1-2 The bottom ash F is subjected to air classification, and the fine bottom ash is separated in the secondary primary air g. 1-2 Under the action of the fluidization stage C, the coarse bottom ash enters the secondary primary air g. 1-2 Under the influence of the air, it enters the bottom ash cooling section A. Secondary primary air g 1-2 It can also be used as bottom fluidizing air to fluidize the bottom ash entering throat section B. Secondary primary air g 1-2 The secondary primary air g is evenly introduced from the side wall of the throat segment B.1-2 The wind speed is 30-100 m / s, level 2 primary wind g 1-2 The air is selected from at least one of water vapor, oxygen, air, and carbon dioxide, with an oxygen concentration of 21%-50%. The apparent wind velocity at the throat is 4m / s-12m / s to ensure sufficient air classification time to separate and fluidize the coarse and fine bottom ash in the bottom ash F. A third-stage primary air g is introduced into the supplementary fluidization section C. 1-3 Strengthen Level III wind g 1-3 Fluidization and gasification of gasification feedstock D and solid materials; wherein, the primary air of stage III g 1-3 To replenish the primary air with fluidizing gas, the air volume is such that the apparent fluidization velocity at the horizontal plane where the primary air duct 19 is located is 2.5-5 m / s. (Primary air g) 1-3 The airflow is introduced into the supplementary fluidization section C via a tangential circular flow through the primary air duct 19, where the air velocity is 30-100 m / s to create strong turbulence. Furthermore, the distance between the primary air duct 19 and the top of the throat section B is 0.5-3.0 m.

[0075] By employing the aforementioned staged air distribution method, coarser slag blocks can be smoothly discharged from gasifier 1-1. The bottom slag cooling section A further serves to recover waste heat, reusing the heat from the slag blocks for the gasification reaction. Furthermore, to cool the slag blocks more rapidly, water sprayed from the water atomization unit installed in the bottom slag cooling section A can be used to cool the bottom slag F.

[0076] In summary, the gasification feedstock graded gasification system proposed in this disclosure is divided into fluidized bed gasification and high-temperature gasification according to the degree of difficulty in gasifying the gasification feedstock, thereby achieving higher carbon conversion rate and thermal efficiency.

[0077] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A staged gasification system for gasification feedstock, characterized in that, The staged gasification system includes: A fluidized bed gasification reactor includes a gasifier consisting of a turbulent fluidization section, a connecting section, and a transport section. The turbulent fluidization section and the transport section are connected by the connecting section to discharge crude gas and fly ash from the gasifier. The turbulent fluidization section includes, from bottom to top, a dense phase zone, a transition zone, and a dilute phase zone. A primary air inlet and a ash discharge port for discharging bottom ash are provided at the bottom of the gasifier. A gasification feedstock inlet is provided in the dilute phase zone, and a nozzle is provided at the top of the dilute phase zone. The dust removal unit, located downstream of the fluidized bed gasification reactor, is used to collect the fly ash discharged from the gasifier to achieve gas-solid separation of the crude gas and fly ash. The high-temperature gasification reactor is located downstream of the dust removal unit. It is equipped with a gasifying agent duct, a fly ash duct connected to the dust removal unit, and a discharge port for discharging high-temperature coal gas and high-temperature ash. The discharge port is connected to the nozzle to form a fly ash circulation loop, so that the high-temperature coal gas and high-temperature ash generated by the gasification of fly ash can be injected into the gasifier through the nozzle, so as to utilize the sensible heat of the high-temperature coal gas and high-temperature ash in the fluidized bed gasification reaction.

2. The staged gasification system according to claim 1, characterized in that, The staged gasification system also includes: The waste heat recovery unit is located downstream of the fluidized bed gasification reactor and upstream of the dust removal unit, and is used to recover the heat from the crude coal gas and fly ash.

3. The staged gasification system according to claim 1, characterized in that, The fluidized bed gasification reactor also includes: An air distribution unit is located at the bottom of the gasifier so that primary air can enter the gasifier for fluidization and gasification. The gas-solid separator is provided with a gasification product inlet connected to the outlet of the conveying section, a gaseous material outlet for discharging the crude coal gas and fly ash, and a solid material outlet for discharging solid materials. A return feeder, located downstream of the gas-solid separator, is provided with a return inlet connected to the solid material outlet and a return outlet for discharging the solid material; and The gasifier is also provided with a return port connected to the return outlet of the return feeder; The air distribution unit includes an air cap, an air distribution plate, and an air chamber; the included angle between the return port and the connection port is 90°-180°, the height of the return port from the air distribution plate is 0.5m-3.5m, and the height difference between the connection port and the return port is 0.2m-5.0m.

4. The staged gasification system according to claim 3, characterized in that, A connection port for connecting the connecting segment is provided on the sidewall of the transition zone, and a section of tactile paving is provided at one end of the connecting segment away from the connection port. The angle between the centerline of the connecting segment and the horizontal line is 30°-70°, and the length of the tactile paving is 0.2-1.25 times the diameter of the connecting segment; or A connection port is provided at the top of the dilute phase zone to connect the center of the top of the connecting section and the top of the turbulent fluidization section through the connection port. The nozzle is located at the top of the gasifier, and the angle between the centerline of the nozzle and the centerline of the turbulent fluidization section is 10°-45°.

5. The staged gasification system according to claim 4, characterized in that, The connection between the connecting section and the transport section extends along the gas direction, and a secondary air duct for secondary air to enter is provided in the transport section along the gas extension direction. The secondary air ducts are multiple, located on the same horizontal plane and arranged tangentially around the transport section. The angle between the axial direction and the horizontal direction when the secondary air enters the transport section is ±30°. The tangential diameter d of the secondary air duct is between 0.5 times the diameter of the connecting section and 0.80 times the diameter of the cross section where the center line of the secondary air duct nozzle is located.

6. The staged gasification system according to claim 5, characterized in that, The high-temperature gasification reactor is a one-stage or two-stage gasification reactor with burner components. The gasification reactor with burner assembly includes: a cylindrical body, and a burner assembly located at the top of the cylindrical body; the burner assembly consists of a fly ash duct and a gasifying agent duct, wherein the fly ash duct is located on the center line of the high-temperature gasification reactor, and the gasifying agent duct is arranged around the fly ash duct. The height-to-diameter ratio of the high-temperature gasification reactor is 2-3.5; In the case where the high-temperature gasification reactor is a two-stage gasification reactor with burner components: The two-stage gasification reactors with burner components have the same structure. The ash discharge port of the first gasification reactor with burner components serves as the inlet of the fly ash duct of the second gasification reactor with burner components. The second gasification reactor with burner components is also equipped with a second gasifying agent duct. The first gasification reactor with burner structure serves as a non-slag zone for gasification reaction, producing crude high-temperature coal gas and non-slag high-temperature ash. The second gasification reactor with burner structure serves as a slag zone to gasify the carbon and crude high-temperature coal gas in the non-slag high-temperature ash, producing reformed high-temperature coal gas and high-temperature ash.

7. The staged gasification system according to any one of claims 1-6, characterized in that, Water atomizing nozzles are arranged around the nozzle to cool the high-temperature coal gas and high-temperature ash sprayed from the nozzle with water.

8. The staged gasification system according to claim 7, characterized in that, The dense phase zone, from bottom to top, includes: a bottom ash cooling section, a throat section, and a supplementary fluidization section; The bottom of the bottom ash cooling section is provided with a primary air inlet for primary air to enter, and a ash discharge port for discharging bottom ash is provided on the side wall. The throat section is provided with a secondary primary air duct for secondary primary air to enter, and the height-to-diameter ratio of the throat section is 0.5-2. The supplementary fluidization section is equipped with multiple tertiary primary air ducts, which are located on the same horizontal plane. The centerline of each tertiary primary air duct makes an angle of 8°-30° with the horizontal line and is arranged in an upwardly inclined tangent circle around the supplementary fluidization section. The diameter of the tangent circle is 0.5-0.85 times the diameter of the throat section and the diameter of the horizontal plane where the tertiary primary air ducts are located. The distance between each tertiary primary air duct and the top of the throat section is 0.5m-3m. Preferably, the bottom slag cooling section is further provided with a water spray atomization unit.

9. A method for staged gasification of gasification feedstock, employing the staged gasification system as described in claim 8, characterized in that, The staged gasification method includes: In the turbulent fluidization section of the gasifier of the fluidized bed gasification reactor, the gasification feedstock is gasified to produce crude coal gas, fly ash, unreacted solid materials and bottom ash; The crude coal gas and fly ash are introduced into the dust removal unit, and the fly ash is captured by the dust removal unit to achieve gas-solid separation of the crude coal gas and fly ash. The fly ash is transported to a high-temperature gasification reactor and gasified with a gasifying agent to produce high-temperature coal gas and high-temperature ash residue. The high-temperature coal gas and high-temperature ash are injected into the gasifier through nozzles located in the dilute phase zone at the top of the gasifier. Under the action of the gas, they come into contact with the turbulent gasification feedstock and the unreacted solid material, so that the gasification feedstock and the unreacted solid material can undergo fluidized bed gasification reaction using the sensible heat of the high-temperature coal gas and high-temperature ash. The unreacted solid material includes semi-coke and circulating ash.

10. The staged gasification method according to claim 9, characterized in that, The staged gasification method further includes: The waste heat recovery unit recovers the heat from the crude coal gas and fly ash, reducing the temperature of the crude coal gas and fly ash to 150-350℃.

11. The staged gasification method according to claim 9, characterized in that, Before entering the waste heat recovery unit, the crude coal gas and fly ash include: After being discharged from the gasifier via the connecting section and the conveying section, the crude coal gas, fly ash, and some of the unreacted solid materials enter the gas-solid separator for gas-solid separation to obtain crude coal gas, fly ash, and the unreacted solid materials. The unreacted solid material is returned to the gasifier via a return feeder to participate in the gasification reaction.

12. The staged gasification method according to claim 11, characterized in that, The crude coal gas, fly ash, and some of the entrained unreacted solid materials are discharged from the gasifier via the connecting section and the conveying section, including: The crude coal gas, fly ash, and some of the unreacted solid materials carried by the gasifier enter the connecting section through a connection port on the side wall of the transition zone. The blind channel in the connecting section enhances the mixing and distribution between the gas and solids, and after uniform mixing, the mixture enters the transport section; or The crude coal gas, fly ash, and entrained unreacted solid materials enter the connecting section and the conveying section through the connection port provided at the top of the gasifier; Secondary air is introduced into the transport section to enhance the mixing of the secondary air with the crude coal gas, fly ash and unreacted solid materials and to carry out gasification reaction, thereby improving carbon conversion rate and pyrolysis volatilization.

13. The staged gasification method according to claim 9, characterized in that, In the case where the high-temperature gasification reactor is a single-stage gasification reactor with burners, the fly ash is gasified to produce high-temperature gas and high-temperature ash residue, including: The fly ash enters the burner structure through the fly ash duct and the gasifying agent enters the burner structure through the gasifying agent duct. Under the action of the burner structure, a gasification reaction is carried out in the gasification reactor to produce high-temperature coal gas and high-temperature ash. In the case where the high-temperature gasification reactor is a two-stage gasification reactor with burners, the fly ash is gasified to produce high-temperature gas and high-temperature ash residue, including: The fly ash and the first gasifying agent enter the first burner organization through the fly ash duct and the gasifying agent duct of the first gasification reactor with burner organization. Under the action of the first burner organization, the gasification reaction is carried out in the first cylinder to produce crude high-temperature coal gas and non-molten slag high-temperature ash. The non-molten slag high-temperature ash and crude high-temperature coal gas are discharged into the fly ash duct of the second-stage gasification reactor with burner organization. Under the action of the second burner organization, the second gasifying agent, which enters through the second gasifying agent duct, undergoes a gasification reaction in the second cylinder to produce reformed high-temperature coal gas and high-temperature ash.

14. The staged gasification method according to any one of claims 9-13, characterized in that, By arranging water atomizing nozzles around the nozzle, the water sprayed from the water atomizing nozzles is used to quench the high-temperature coal gas and high-temperature ash sprayed from the nozzle.

15. The staged gasification method according to claim 14, characterized in that, The dense phase zone, from bottom to top, includes: a bottom ash cooling section, a throat section, and a supplementary fluidization section; Primary air is introduced into the bottom ash cooling section to reduce the temperature of the bottom ash; Secondary primary air is introduced into the throat section to perform air separation on the bottom ash. Fine bottom ash enters the supplementary fluidization section under the action of the secondary primary air, while coarse bottom ash enters the bottom ash cooling section under the action of the secondary primary air. A third-stage primary air is introduced into the supplementary fluidization section to enhance the fluidization and gasification of the third-stage primary air with the gasification feedstock and the solid material; Preferably, the bottom slag is cooled by water sprayed from the water atomization unit installed in the bottom slag cooling section.

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