Biomass and coal gasification fine slag synergistic gasification method and system

Abstract

The application relates to the technical field of biomass gasification, and discloses a biomass and coal gasification fine slag synergic gasification method and system. After the biomass and the coal gasification fine slag are respectively pretreated, the biomass and the coal gasification fine slag are sent into a mixing and grinding unit to be mixed and ground to generate mixed powder; subsequently, the mixed powder and a gasification agent are synchronously sprayed into a gas flow bed gasification furnace to occur a synergic gasification reaction. In the high-temperature reaction process, gaseous alkali metal chlorides released by the biomass are combined with silicon-aluminum components in the fine slag in situ to be converted into silicate and aluminate, and are solidified in liquid slag to be discharged from the system. The generated crude synthesis gas enters a full waste heat boiler waste heat recovery unit to be subjected to stepwise temperature reduction treatment and recover sensible heat, and finally, clean synthesis gas is output after dust removal. The application in-situ solidifies alkali metals released by biomass gasification, avoids contamination and corrosion problems of downstream waste heat recovery equipment, improves the thermal efficiency of the system, and realizes synergic resource utilization of coal chemical industry solid waste and biomass.

Description

Technical Field

[0001] This application relates to the field of biomass gasification technology, specifically a method and system for the co-gasification of biomass and coal gasification slag. Background Technology

[0002] Biomass, as a renewable energy source with abundant reserves, is converted into syngas through gasification technology, which is an important way to realize resource utilization. During biomass gasification, biomass feedstock generally contains high levels of alkali metals and chlorine. These alkali metals are easily volatilized under high-temperature gasification conditions and mix into the generated crude syngas in the form of gaseous alkali metal chlorides. When the crude syngas containing gaseous alkali metals enters the downstream cooling section, the alkali metal compounds condense and deposit on the surface of the heat exchange equipment, causing severe fouling, slagging, and high-temperature corrosion of the heat exchange tubes.

[0003] Furthermore, in fluidized bed gasification processes, biomass ash content is typically low, resulting in insufficient slag formation during gasification, making it difficult to create a continuous, stable, and uniform slag layer on the gasifier wall. Simultaneously, the high content of alkali metals such as K and Na in biomass ash leads to a low ash melting point, with a flow temperature typically only between 900℃ and 1100℃. In the high-temperature fluidized bed gasification environment of 1200℃ to 1500℃, the slag viscosity is too low and its fluidity too high, making stable slag adhesion difficult. This easily leads to slag layer thinning or peeling, directly exposing the furnace wall refractory lining or water-cooled wall to high-temperature gas flow erosion, thermal corrosion, and alkali metal corrosion, affecting the long-term stable operation of the gasifier. Therefore, how to adjust the total amount and melting characteristics of biomass ash through external additives to achieve slag-resistant self-protection of the gasifier wall is a pressing technical challenge in the current biomass gasification field.

[0004] Meanwhile, coal gasification processes generate a large amount of gasification slag during operation. This slag is a major industrial solid waste, characterized by high moisture content and a certain proportion of unreacted carbon residue. Current treatment methods primarily involve direct stockpiling or landfilling, posing significant environmental pollution risks and high processing costs. The unreacted carbon residue in the coal gasification slag or fly ash undergoes high-temperature thermal shock during the original coal gasification process, resulting in a more ordered carbon microcrystalline structure, a higher degree of graphitization, and a reduced number of active sites. This leads to lower regasification reactivity and limited carbon conversion. Because conventional methods struggle to break down this highly graphitized microcrystalline carbon structure, the secondary gasification utilization of this slag residue is extremely challenging.

[0005] Theoretically, the alkali / alkaline earth metals naturally present in biomass, such as K, Na, Ca, and Mg, can act as in-situ catalytic components, promoting the reaction between residual char and gasifying agents such as steam and carbon dioxide before solidification by the aluminosilicate slag phase. This reduces the activation energy of the residual char gasification reaction and increases the gasification rate. However, in existing technologies, the challenge lies in constructing a reasonable process that can effectively catalyze the graphitization of residual char in coal gasification slag by utilizing the high alkali metal content of biomass, while simultaneously leveraging the silica-alumina components in the slag to address the problems of biomass' low ash melting point, inability to adhere slag, and susceptibility to alkali metal leaching and corrosion. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this application provides a method and system for the co-gasification of biomass and coal gasification fine slag. This method solves the problem that the volatilization of alkali metals during the existing biomass gasification process leads to fouling, slagging, and corrosion of downstream waste heat recovery equipment, which in turn restricts the efficient recovery of sensible heat from syngas. It also solves the problems of high operating costs caused by relying on purchased additives to solidify alkali metals in traditional processes, as well as the difficulty in large-scale resource utilization of fine slag from coal chemical solid waste gasification.

[0007] To achieve the above objectives, this application provides the following technical solution:

[0008] The first aspect of this application provides a method for co-gasification of biomass and coal gasification fine residue, comprising the following steps: Biomass raw materials are fed into a biomass pretreatment unit for crushing and drying, or for crushing, drying and baking, to generate pretreated biomass raw materials. Simultaneously, the coal gasification fine slag is sent to the fine slag pretreatment unit for drying, dehydration and pulverization to generate pretreated coal gasification fine slag. The pretreated biomass raw material and the pretreated coal gasification fine slag are fed into a mixing and grinding unit for mixing and grinding to generate mixed powder. The mixed powder and gasifying agent are simultaneously injected into the fluidized bed gasifier, where a synergistic gasification reaction occurs. During this reaction, the alkali metals and alkaline earth metals in the pretreated biomass feedstock come into contact with the residual carbon in the pretreated coal gasification slag and act as electron transfer mediators to promote the catalytic gasification reaction of the residual carbon. Simultaneously, the gaseous alkali metal chlorides or free potassium and sodium ions released from the pretreated biomass raw materials undergo in-situ coordination and bonding reactions with the silica and alumina in the pretreated coal gasification fine slag. The in-situ bonding transforms into a chemical substance in the form of a high-melting-point aluminosilicate complex salt mineral crystalline phase. The generated complex salt mineral crystalline phase adheres to the wall of the fluidized bed gasifier to form a slag layer, while the remaining unattached reactants gather to form liquid slag and crude syngas. The liquid slag is discharged into the slag discharge unit for quenching, generating solid coarse slag which is then discharged from the system. The crude syngas is sent to the waste heat recovery unit of the waste boiler for step cooling and sensible heat recovery to generate cooled crude syngas. The cooled crude syngas is sent to a syngas purification unit for separation and dust removal, and clean syngas is output.

[0009] Preferably, when the biomass pretreatment unit crushes, dries, and bakes the biomass raw material to generate the pretreated biomass raw material, it specifically includes: The biomass raw material is fed into the crushing device inside the biomass pretreatment unit for crushing and processing to generate biomass pellets. The biomass pellets are fed into the drying device inside the biomass pretreatment unit for drying to remove moisture and generate dry biomass pellets. The dried biomass pellets are fed into a baking device inside the biomass pretreatment unit for baking to generate the pretreated biomass raw material.

[0010] Preferably, the coal gasification fine slag is fed into the fine slag pretreatment unit for drying, dehydration, and pulverization to generate the pretreated coal gasification fine slag, including: The coal gasification fine slag is fed into the fine slag drying device inside the fine slag pretreatment unit for fine slag drying and dehydration treatment to generate dried fine slag. The dried fine slag is fed into the fine slag pulverizing device inside the fine slag pretreatment unit for fine slag pre-grinding and pulverizing treatment to generate the pretreated coal gasification fine slag.

[0011] Preferably, the pretreated biomass raw material and the pretreated coal gasification fine slag are fed into the mixing and grinding unit for mixing and grinding to generate the mixed powder, comprising: The pretreated biomass raw materials and the pretreated coal gasification fine slag are simultaneously fed into the proportioning and weighing device inside the mixing and pulverizing unit for online proportioning and feeding, generating a mixture of materials gathered according to a preset mass ratio. The mixture of materials gathered according to a preset mass ratio is fed into the main grinding equipment inside the mixing and powdering unit for joint grinding and homogenization, so that the two phases are uniformly dispersed and mixed at the micro-particle level to generate the mixed powder.

[0012] Preferably, the mixed powder and the gasifying agent are simultaneously injected into the interior of the fluidized bed gasifier, comprising: The gasifying agent is generated by mixing high-purity oxygen and superheated steam. Using carrier gas as the transport medium, the mixed powder and the carrier gas form a dense gas-solid two-phase flow and are fed into the process burner of the fluidized bed gasifier, while the gasifying agent is introduced into the process burner. The mixed powder and the gasifying agent are simultaneously injected into the high-temperature furnace space inside the fluidized bed gasifier through the process burner.

[0013] Preferably, the synergistic gasification reaction process occurring inside the fluidized bed gasifier specifically includes: Under the high-temperature environment generated by the synergistic gasification reaction, the alkali metals and alkaline earth metals in the pretreated biomass raw material precipitate out and react with the residual carbon in the pretreated coal gasification fine slag before being solidified. The gaseous alkali metal chlorides or free potassium and sodium ions after the gasification reaction occur, and the silica and alumina in the pretreated coal gasification fine slag undergo an in-situ coordination reaction at high temperature, combining and transforming into a complex salt mineral crystalline phase. A portion of the complex salt mineral crystalline phase adheres to the wall of the fluidized bed gasifier to form the slag layer, while the remaining complex salt mineral crystalline phase converges and integrates into the interior of the liquid slag, thereby confining the alkali metal within the liquid slag and completing its solidification.

[0014] Preferably, the liquid slag is discharged into the slag discharge unit for quenching to generate the solid coarse slag, which is then discharged out of the system, including: The liquid slag is discharged through the slag discharge port at the bottom of the fluidized bed gasifier into the quench water bath slag pool inside the slag discharge unit; The liquid slag comes into contact with cooling water inside the quench water bath slag pool and undergoes heat exchange, and the liquid slag cools down to form the glassy solid coarse slag; The solid coarse slag is discharged out of the system through the slag collection device at the bottom of the slag discharge unit.

[0015] Preferably, the crude syngas is fed into the waste heat recovery unit of the total waste boiler for staged cooling and sensible heat recovery to generate the cooled crude syngas, including: The crude syngas is fed into the radiant waste boiler inside the waste heat recovery unit of the waste boiler for high-temperature radiant cooling treatment. The high-temperature sensible heat carried by the crude syngas is transferred to the desalination boiler water to generate high-pressure or medium-pressure steam, and at the same time, crude syngas that has been radiantly cooled is generated. The radiatively cooled crude syngas is fed into the convective waste boiler inside the waste heat recovery unit for medium-temperature convective cooling. The medium- and low-temperature sensible heat carried by the radiatively cooled crude syngas is transferred to the boiler feedwater or low-pressure steam medium, while the cooled crude syngas is generated.

[0016] Preferably, the cooled crude syngas is fed into the syngas purification unit for separation and dust removal, and clean syngas is output, including: The cooled crude syngas is fed into a porous filter element inside the syngas purification unit for dry dust removal and filtration. The porous filter element intercepts dry fly ash particles contained in the cooled crude syngas, thereby removing solid impurities and outputting clean syngas.

[0017] The second aspect of this application provides a co-gasification system for biomass and coal gasification fine residue, comprising: A biomass pretreatment unit receives biomass raw materials and performs crushing and drying treatment on the biomass raw materials, or performs crushing, drying and baking treatment to generate pretreated biomass raw materials. The fine slag pretreatment unit receives coal gasification fine slag, and the fine slag pretreatment unit performs drying, dehydration and pulverization treatment on the coal gasification fine slag to generate pretreated coal gasification fine slag; A mixing and grinding unit is connected to the biomass pretreatment unit and the fine residue pretreatment unit. The mixing and grinding unit receives the pretreated biomass raw material and the pretreated coal gasification fine residue. The mixing and grinding unit mixes and grinds the pretreated biomass raw material and the pretreated coal gasification fine residue to generate mixed powder. A gasifying agent supply unit is connected to the fluidized bed gasifier, and the gasifying agent supply unit supplies gasifying agent to the fluidized bed gasifier; A fluidized bed gasifier is connected to the mixed pulverizing unit. The fluidized bed gasifier receives the mixed powder and the gasifying agent. A synergistic gasification reaction occurs inside the fluidized bed gasifier. During this reaction, alkali metals and alkaline earth metals in the pretreated biomass feedstock come into contact with the residual carbon in the pretreated coal gasification fine slag and act as electron transfer mediators to promote the catalytic gasification reaction of the residual carbon. Gaseous alkali metal chlorides or free potassium and sodium ions released from the pretreated biomass feedstock undergo in-situ coordination and combination reactions with silica and alumina in the pretreated coal gasification fine slag, transforming them into chemical substances in the form of complex salt mineral crystal phases of leucite and mullite. These crystal phases adhere to the wall of the fluidized bed gasifier to form a slag layer, and liquid slag and crude syngas are generated. The slag removal unit is connected to the fluidized bed gasifier. The slag removal unit receives the liquid slag, quenches the liquid slag to generate solid coarse slag, and discharges it out of the system. The waste heat recovery unit of the waste boiler is connected to the fluidized bed gasifier. The waste heat recovery unit of the waste boiler receives the crude syngas and performs step cooling treatment on the crude syngas and recovers sensible heat to generate cooled crude syngas. The syngas purification unit is connected to the waste heat recovery unit of the waste boiler. The syngas purification unit receives the cooled crude syngas and performs separation and dust removal treatment on the cooled crude syngas to output clean syngas.

[0018] This application provides a method and system for co-gasification of biomass and coal gasification fine slag. It has the following beneficial effects: 1. This application effectively solves the problem of alkali metal release during biomass gasification by mixing and grinding biomass with coal gasification fine slag and then co-gasifying them. Under the high-temperature environment of the gasifier, the gaseous alkali metal chlorides volatilized from biomass can undergo in-situ coordination reactions with the silica and alumina components abundant in the coal gasification fine slag, transforming into high-melting-point complex salt mineral crystalline phases (aluminosilicates) and discharging them into the liquid slag. This solidifies the free alkali metals in the bottom slag, reducing the content of alkali metal aerosols in the syngas and preventing contamination, slagging, and high-temperature corrosion in downstream systems from the source.

[0019] 2. This application improves the sensible heat recovery efficiency of the gasification system and ensures the long-term stable operation of the waste heat recovery equipment. Since alkali metals are effectively captured and solidified by the fine slag in the front-end gasification reaction, the generated crude syngas has low alkali metal characteristics. Therefore, the back-end process can directly use a full waste heat recovery unit to perform cascade cooling of the crude syngas. Through the combination of radiant and convective waste heat boilers, the sensible heat carried by the syngas can be fully recovered to produce steam as a byproduct, improving the overall thermal efficiency of the system while avoiding the waste heat boiler tube blockage problem caused by alkali metal enrichment in conventional biomass gasification processes.

[0020] 3. This application achieves the synergistic resource utilization of industrial solid waste and renewable organic resources. Coal gasification slag is a major solid waste generated by the coal chemical industry. This application pre-treats it and blends it with biomass as a raw material before feeding it into the gasifier. This utilizes the inorganic silica-alumina ash in the slag as an alkali metal solidifying agent and converts the remaining unreacted carbon into syngas components. This reduces the operating cost of burning biomass alone and provides a feasible technical approach for the large-scale disposal and harmless treatment of coal chemical gasification slag. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method in this application; Figure 2 This is a system architecture diagram for this application; Figure 3 Comparison of experimental results of the biomass co-gasification process provided in this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] See attached document Figure 1 and attached Figure 2 This application provides a co-gasification system for biomass and coal gasification fine residue, comprising: The system includes a biomass pretreatment unit, a fine slag pretreatment unit, a mixed grinding unit, a fluidized bed gasifier, a gasifying agent supply unit, a slag discharge unit, a waste heat recovery unit from the waste boiler, and a syngas purification unit.

[0024] The raw material output end of the biomass pretreatment unit is connected to the first input end of the mixing and milling unit for receiving and processing biomass raw materials.

[0025] The raw material output end of the fine slag pretreatment unit is connected to the second input end of the mixing and pulverizing unit, and is used to receive and process the coal gasification fine slag raw material.

[0026] The output end of the mixing and grinding unit is connected to the material input end of the fluidized bed gasifier. The mixing and grinding unit is used to mix and grind the treated biomass raw materials and coal gasification fine slag raw materials at a set mass ratio to generate mixed powder.

[0027] The output end of the gasifying agent supply unit is connected to the gasifying agent input end of the fluidized bed gasifier, and is used to supply the fluidized bed gasifier with a gasifying agent containing pure oxygen or oxygen-enriched gas and water vapor.

[0028] The fluidized bed gasifier, as the core reactor for co-gasification, is equipped with process burners at its top for receiving the mixed powder and gasifying agent. A slag discharge port is located at the bottom of the gasifier, connected to the slag discharge unit. A syngas outlet is located on the side or bottom of the gasifier, connected to the input of the waste heat recovery unit.

[0029] The slag discharge unit is used to receive the liquid slag discharged from the fluidized bed gasifier and quench it before discharging it out of the system.

[0030] The output of the waste heat recovery unit is connected to the input of the syngas purification unit. The waste heat recovery unit contains radiant waste heat boilers and convective waste heat boilers connected in series, which are used to perform stepped cooling of the high-temperature crude syngas from the fluidized bed gasifier and recover sensible heat.

[0031] The syngas purification unit has a syngas output end, which is used to remove dust from the cooled crude syngas and finally output clean syngas.

[0032] See attached document Figure 1 This paper provides a method for the co-gasification of biomass and coal gasification fine residue. Based on the above system architecture, the overall workflow of this application is as follows: In the initial stage, biomass feedstock is fed into the biomass pretreatment unit, where it undergoes crushing, drying, and baking processes to complete its pretreatment. Simultaneously, coal gasification fines enter the fines pretreatment unit, where they undergo drying to complete their pretreatment.

[0033] Subsequently, the pretreated biomass feedstock and the pretreated coal gasification slag are fed into the mixing and grinding unit. Inside the mixing and grinding unit, the two feedstocks are mixed and ground in a set ratio to ensure that the particle size meets the feeding requirements of fluidized bed gasification, forming a uniform mixed powder.

[0034] The mixed powder is conveyed to the fluidized bed gasifier via a high-pressure dense-phase conveyor. The gasifying agent supply unit simultaneously delivers a set ratio of oxygen and water vapor to the fluidized bed gasifier. The mixed powder and gasifying agent are then injected into the fluidized bed gasifier through process burners.

[0035] Under the high temperature and high pressure environment of the fluidized bed gasifier, biomass in the mixed powder undergoes a synergistic gasification reaction with the coal gasification slag. The liquid slag generated during the gasification process flows downwards along the inner wall of the fluidized bed gasifier and falls into the slag discharge unit through the slag discharge port at the bottom. The liquid slag is quenched and cooled within the slag discharge unit to form solid coarse slag, which is then discharged.

[0036] The crude syngas generated by the gasification reaction in the fluidized bed gasifier is discharged from the syngas outlet and directly enters the waste heat recovery unit of the waste boiler. The crude syngas flows sequentially through the radiant waste boiler and the convective waste boiler, releasing high-temperature sensible heat and medium-temperature sensible heat during the cooling process, thus completing the cascade waste heat recovery.

[0037] Finally, the crude syngas, after being cooled in stages, enters the syngas purification unit. The purification unit separates fly ash particles entrained in the crude syngas at high temperatures, ultimately obtaining clean syngas for downstream processes.

[0038] Combined with appendix Figure 1 and Figure 2 The internal hardware composition of the biomass pretreatment unit and its corresponding processing technology flow in this embodiment are described in detail.

[0039] The biomass pretreatment unit contains a crushing device, a drying device, and a baking device connected in sequence. For the specific internal mechanical structure of the crushing device, those skilled in the art can use conventional hammer crushers, jaw crushers, or double-roll shear crushers; their mechanical shearing and impact principles are well-known in the field and will not be elaborated upon here. The drying device can be a drum dryer or a fluidized bed dryer. The baking device can be any one of a rotary baking oven, a fixed-bed baking oven, a moving-bed baking oven, or a fluidized bed baking oven, selected and configured according to the actual project footprint and processing capacity requirements.

[0040] For the raw materials fed into the biomass pretreatment unit, the pretreatment process is specifically divided into the following steps: Raw material crushing. The raw biomass material is fed into the crushing device via a conveyor belt or feeder. The crushing device coarsely crushes and segments large pieces of raw material, controlling the output biomass particles to have a particle size of no more than 10 mm.

[0041] Raw material drying. The coarsely crushed biomass pellets enter a drying unit for dehydration. Hot air or other heating media are introduced to evaporate the internal moisture of the biomass pellets. The operating parameters of the drying unit are controlled to reduce the moisture content of the output dried biomass pellets to no more than 15%.

[0042] Raw material roasting. The dried biomass pellets are fed into the roasting apparatus for heat treatment. The internal operating temperature of the roasting apparatus is set between 200℃ and 300℃, and the residence time of the material in the roasting apparatus is controlled between 20 minutes and 60 minutes.

[0043] In practical industrial applications, depending on the characteristics and chemical composition differences of the raw materials, the above-mentioned raw material crushing, drying, and baking steps can be combined in different ways.

[0044] When the system processes herbaceous biomass raw materials with high alkali metal content and low ash melting point, specifically including crop straw, the process involves raw material crushing, drying, and roasting in sequence. In this process, the biomass undergoes pyrolysis within a set temperature range in the roasting device.

[0045] Under this thermal environment, the naturally occurring cellulose and hemicellulose macromolecules in biomass undergo partial degradation and depolymerization, disrupting the original flexible fiber cross-linked structure of the biomass. This disintegration directly weakens the toughness of the biomass particles and increases their brittleness, improving the mechanical grindability of the raw material, thereby reducing mechanical energy consumption and equipment wear in subsequent grinding processes.

[0046] Meanwhile, some volatile alkali metal compounds and chlorine-containing components are released and removed during the pyrolysis process along with the volatile fractions.

[0047] In a process route that includes a raw material baking step, a mass yield parameter is introduced for online evaluation and control of the process state by comparing the total mass of the dried biomass particles before entering the baking device with the total mass of the solid products collected after baking, thereby quantifying the material loss boundary during the pyrolysis process.

[0048] When the system processes woody biomass raw materials with low ash content and low alkali metal content, and the specific sub-concepts include wood processing waste or firewood, a non-baking operation process is adopted that only performs raw material crushing and drying.

[0049] In this process, biomass pellets are crushed by a crushing unit and dried by a drying unit, then skip the baking unit and are output as intermediate processed material to the next stage. This no-baking process eliminates the extra heat energy consumption associated with heat treatment, shortens the process flow, and is suitable for conventional hard biomass that does not require deep de-hardening and de-alkali treatment.

[0050] Combined with appendix Figure 1 and Figure 2 The internal hardware composition of the fine slag pretreatment unit and its corresponding processing flow are described in detail in this embodiment.

[0051] The internal hardware of the fine slag pretreatment unit typically includes a fine slag drying device and a fine slag pulverizing device connected in sequence. For the specific type of fine slag drying device, any one of a rotary drum dryer, a disc continuous dryer, or a paddle dryer can be used. For the specific structure of the fine slag pulverizing device, those skilled in the art can choose conventional grinding equipment such as ball mills, vertical roller mills, or Raymond mills. The principle of reducing solid particle size through the mechanical extrusion, impact, and friction of the internal grinding media or rollers is well-known in the art and will not be elaborated further here.

[0052] The coal gasification fine slag feedstock connected to the fine slag pretreatment unit has specific physicochemical properties. This coal gasification fine slag originates from a byproduct discharged during coal gasification in a fluidized bed or entrained gasification process. Through screening of the material source and component testing, it is ensured that the total mass fraction of silica and alumina in the input coal gasification fine slag is not less than 60%, while the mass fraction of residual carbon in the fine slag is controlled within the range of 20% to 40%. The specific inorganic mineral content and residual carbon content settings provide a material basis for subsequent in-situ chemical reactions in the gasifier and the secondary utilization of carbon resources.

[0053] The material entering the fine slag pretreatment unit is processed according to the following steps: Fine slag drying and dehydration. The raw coal gasification fine slag, carrying free moisture, is fed into the fine slag drying unit. By introducing heating media such as hot flue gas or heat transfer oil, the fine slag is continuously heated and turned, promoting the evaporation of moisture from the inside and surface of the material. By controlling the operating temperature and material residence time of the fine slag drying unit, the moisture content of the output dried fine slag is reduced to no more than 5%.

[0054] In the fine residue drying process, the system monitors the wet basis moisture content of the fine residue entering and exiting the drying unit in real time, comparing it with the oven-dry mass of the same batch of material to monitor the operating status of the drying unit. By collecting and calculating the above moisture removal indicators in real time, the system dynamically adjusts the heat input of the fine residue drying unit to ensure that the output material meets the preset indicators.

[0055] Fine slag pre-grinding. After drying and dehydration, the coal gasification fine slag is fed into the fine slag grinding device via a conveying equipment. Under the action of mechanical grinding force, the fine slag particles are further crushed and dissociated. The speed of the classifier or the grinding pressure parameters of the fine slag grinding device are adjusted to control the particle size of the discharged coal gasification fine slag powder to be no greater than 0.1 mm. This particle size control requirement is equivalent to the material being able to completely pass through a 100-mesh standard analytical sieve, thereby ensuring that the material fineness meets the boundary conditions for uniform suspension and rapid mass transfer reaction of particles in the gas phase during subsequent fluidized bed gasification operations. After the above steps, the coal gasification fine slag is sent to the mixing and pulverizing unit for standby.

[0056] Combined with appendix Figure 1 and Figure 2 The internal hardware structure of the mixing and powdering unit in this embodiment and its corresponding mixing process are described in detail.

[0057] The main hardware architecture of the mixing and grinding unit includes a proportioning and weighing device, a main grinding equipment, and a mixing silo connected in sequence. The proportioning and weighing device may be an electronic belt scale or a loss-in-weight feeder. The main grinding equipment can be any type selected from ball mills, vertical roller mills, or high-speed blade mills, depending on the project scale. For the specific internal cutting, crushing transmission structure, and working principle of the classifying wheel of the grinding equipment, those skilled in the art can refer to standard material crushing design manuals for standard selection and configuration. Its crushing operation mechanism is well-known technology in the field and will not be elaborated upon here.

[0058] The raw materials fed into the mixing and milling unit come from two independent upstream processing paths, where they converge and blend within this area. The specific mixing and milling operation process is divided into the following steps: Online proportioning and feeding. The biomass feed from the biomass pretreatment unit, after being crushed, dried, or baked, and the dried coal gasification fine slag from the fine slag pretreatment unit, are simultaneously and continuously fed into the proportioning and weighing device. The central control system dynamically adjusts the speed of the feed frequency converter by collecting real-time signals from the weighing sensors to control the mixing ratio of the two materials. In specific operation, the mass ratio of biomass to coal gasification fine slag fed into the main grinding equipment is strictly controlled to be maintained between 100:5 and 100:40.

[0059] In the material proportioning control stage, the system introduces a proportioning state coefficient to calibrate the stability of material input online, based on the relative relationship between the cumulative mass of coal gasification slag and the cumulative mass of biomass input within a set statistical time period. Under stable operating conditions, the proportioning state coefficient is forcibly controlled to remain constant within the value range of 0.05 to 0.40 according to adjustments made based on material property parameters, thereby ensuring the uniformity of the mixed powder components.

[0060] Combined grinding and homogenization. The mixture, collected according to a preset mass ratio, enters the main grinding equipment, where it undergoes simultaneous crushing and mechanical stirring under the pressure of the grinding rollers or the shearing action of the blades. During the grinding process, the surfaces of the biomass particles and fine residue particles collide and rub violently, achieving uniform dispersion and mixing of the two phases at the microscopic particle level. The powder selection frequency of the separator at the tail end of the main grinding equipment is adjusted to control the particle size of the mixed powder discharged from the main grinding equipment to be no greater than 0.1 mm. This upper limit particle size is equivalent to the material passing through a standard test sieve with a 100-mesh aperture, to meet the boundary requirements for particle specific surface area in the subsequent fluidized bed suspension reaction.

[0061] The mixed powder is temporarily stored in a warehouse. Mixed powder with acceptable particle size is conveyed via pneumatic conveying pipelines into a sealed mixing silo for centralized storage. A high-pressure feeder is connected to the bottom of the mixing silo, serving as a material buffer node for the core gasification reaction system.

[0062] During the aforementioned grinding and reconstitution process, the energy consumption of the grinding equipment is directly related to the pretreatment mode of the upstream biomass. When the upstream undergoes a baking pretreatment operation at 200℃ to 300℃, the original flexible cross-linked fiber network inside the biomass raw material breaks down, and structural substances such as lignin are partially degraded. This structural change results in the material exhibiting significant brittleness. Compared to normal biomass raw materials that undergo only room temperature crushing, this heat-treated material shows reduced toughness against mechanical tearing when ground by the main grinding equipment. This morphological change reduces the mechanical energy consumption of the main grinding equipment during fracture and peeling actions, thereby slowing down the abrasive wear rate on the surface of the metal grinding parts.

[0063] Combined with appendix Figure 1 and Figure 2The structural configuration and operation mode of the fluidized bed gasifier and the supporting gasifying agent supply unit in this embodiment are described in detail.

[0064] As a sealed container where the core synergistic gasification reaction occurs, the enclosed structure of the fluidized bed gasifier can be either a refractory brick lining structure or a water-cooled furnace structure, selected based on the operating pressure and the ash melting point of the raw materials. The top or upper side wall of the fluidized bed gasifier is equipped with mounting flanges for fixing and connecting the process burners. For the multi-channel flow design inside the process burners and the initial flow field design inside the fluidized bed gasifier, those skilled in the art can choose conventional three-channel or four-channel pulverized coal burners. The principles of swirl and direct-flow jet matching are well-known in the field and will not be elaborated here.

[0065] The hardware system of the gasifying agent supply unit includes gas generation equipment, buffer tanks, and delivery pipelines. The gas generation equipment includes a cryogenic separation oxygen generator, a pressure swing adsorption oxygen generator, and a high-pressure steam pipeline interface.

[0066] For the feeding and gasifying agent dispensing processes at the front end of the reaction, the process control system executes the following steps: Dense-phase conveying of mixed powder. Qualified mixed powder temporarily stored in the buffer silo of the mixing and pulverizing unit is conveyed using high-pressure carbon dioxide or nitrogen gas as the transport medium. The carrier gas and mixed powder form a dense-phase gas-solid two-phase flow inside the conveying pipeline and are continuously pressurized to the center or inner ring solid material channel of the process burner. The feedforward compressor pressure of the pipeline network is adjusted to ensure that the conveying pressure is higher than the operating back pressure inside the fluidized bed gasifier to prevent high-temperature gas backflow.

[0067] Gasifying agent preparation and introduction. The gasifying agent supply unit continuously injects a mixed gasifying agent into the external annular gas channel of the process burner. This gasifying agent consists of high-purity oxygen and superheated steam. Based on the operating parameters of the gas source generating equipment, the volume concentration of free oxygen in the input gasifying agent is controlled to be no less than 90%. This concentration limit avoids the sensible heat loss caused by a large amount of inert nitrogen entering the furnace and reduces the dilution rate of the syngas. Steam serves as an auxiliary reaction medium and also plays a role in regulating the local extreme temperature of the furnace.

[0068] In the gasifying agent introduction stage, the supply of gasifying agent is dynamically tracked in real time based on the carbon equivalent of the feed material. An oxygen-to-carbon ratio parameter is introduced to quantitatively control the feed ratio, and its calculation formula is defined as: ; in, This indicates the oxygen-to-carbon ratio in real-time operation. This indicates the actual volumetric flow rate of oxygen input from the gasifying agent supply unit to the fluidized bed gasifier within a specific time period. This indicates the oxygen density under operating conditions. This represents the total mass flow rate of the mixed powder entering the gasifier via high-pressure dense-phase conveying within the same time period; This indicates the overall carbon content by mass of the mixed powder, obtained through online or offline testing. The control system changes the oxygen content by adjusting the opening of the oxygen regulating valve. ,Will The value is locked within the target control range.

[0069] Jet mixing and atomized injection. At the end of the process burner, the high-pressure, high-speed gasifying agent gas flow strongly converges with the dense-phase powder flow carrying solid particles. The gasifying agent gas flow utilizes its high kinetic energy to generate shear force, tearing and dispersing the solid powder flow. Biomass particles and coal gasification fine slag particles are fully separated and deagglomerated in a short time, forming a uniformly distributed suspended particle cloud. This particle cloud is injected at high speed into the high-temperature furnace space of the fluidized bed gasifier at a specific diffusion angle, rapidly undergoing heat and mass transfer processes with the high-temperature environment inside the furnace.

[0070] Combined with appendix Figure 1 and Figure 2 The paper provides a detailed description of the operating environment of the mixture after it is injected into the gasifier and the control steps for the synergistic gasification reaction.

[0071] The mixed powder and gasifying agent create an extreme physical and chemical reaction environment inside the fluidized bed gasifier. For the thermal resistance of the refractory material inside the fluidized bed gasifier and the heat transfer of the external water-cooled pipes, those skilled in the art can establish equations based on conventional engineering thermodynamic models. The principles of steady-state and unsteady-state heat conduction calculations are well-known techniques in this field and will not be elaborated upon here.

[0072] The control of gasification reaction operating conditions is divided into the following execution steps: Furnace temperature field establishment and control. The mixture entering the fluidized bed gasifier undergoes a vigorous redox reaction. The central control system maintains the ambient temperature inside the furnace by adjusting the oxygen volume flow rate output from the gasifying agent supply unit and utilizing the heat released from the combustion reaction of carbon and oxygen. Under continuous operation, the operating temperature of the core reaction zone of the fluidized bed gasifier is controlled between 1200℃ and 1500℃. The set lower limit of 1200℃ is used to ensure that the inorganic ash particles in the mixture can absorb enough heat to exceed their ash melting point, thereby transforming into a fluid liquid slag.

[0073] The flow temperature of standalone biomass ash is typically around 900℃ to 1100℃. Under high-temperature gasification conditions in a fluidized bed gasifier, it is prone to problems such as excessively low slag viscosity, excessive fluidity, and difficulty in stable slag adhesion. This application incorporates fine coal gasification slag, allowing the K₂O and Na₂O in the biomass ash to undergo in-situ ash chemical reactions with the SiO₂ and Al₂O₃ in the fine slag at high temperatures. This generates high-melting-point aluminosilicate complex salt mineral crystalline phases, including mullite and / or leucite. The specific chemical forms of these crystalline phases include, but are not limited to, refractory minerals such as leucite, mullite, microcline, or feldspar. This increases the flow temperature of the mixed ash to approximately 1200℃, thereby improving the viscosity-temperature characteristics of the slag and giving the liquid slag suitable fluidity and slag adhesion stability. The set upper temperature limit of 1500℃ is used to limit the thermal erosion and spalling effect of the high-temperature slag on the inner wall of the fluidized bed gasifier, ensuring the equipment's operational cycle.

[0074] System pressure environment construction and maintenance. Based on the fluid resistance loss of the downstream waste heat recovery unit and the inlet pressure boundary requirements of the subsequent chemical synthesis section, the operating back pressure of the fluidized bed gasifier was set. By adjusting the opening of the pneumatic throttle valves in the system's tail-end piping, the operating pressure inside the fluidized bed gasifier was controlled within the gauge pressure range of 0 MPa to 6.5 MPa. In the increased pressure environment, the density of the gas medium increases, and the mean free path of reactant molecules decreases. This directly increases the collision frequency between the gaseous medium and the micropores on the surface of the solid residual carbon, accelerating the gasification reaction rate of the mixture from a physicochemical kinetic perspective.

[0075] Material residence time and flow state are limited. Under the constraints of a given temperature and pressure field, the relative velocity of gaseous and solid phases within the furnace determines the reaction depth. By adjusting the feed load of the mixed powder and the injection velocity of the gasifying agent, operators limit the average residence time of solid reactive particles in the high-temperature zone of the fluidized bed gasifier to between 2 and 8 seconds. This time range ensures the complete breakage and decomposition of carbon-containing macromolecular chains while avoiding excessive reverse reaction of the product gases.

[0076] Under the combined effects of the above-mentioned operating conditions of temperature, pressure, and time, the efficiency of the gasification reaction of the mixture is evaluated and verified in real time by incorporating the carbon conversion rate parameter. The calculation formula is defined as follows: ; in, This indicates the overall carbon conversion rate of the fluidized bed gasifier under the current measured operating conditions; This indicates the total mass of solid coarse slag discharged from the bottom slag outlet within the set sampling time period; This indicates the mass fraction of residual carbon in the solid coarse slag as determined by laboratory dry basis analysis. This represents the total mass of solid fly ash carried out of the fluidized bed gasifier by crude syngas within the same time period; This indicates the mass fraction of residual carbon contained in fly ash; This represents the total mass of mixed powder input into the fluidized bed gasifier through the process burner within the corresponding time period; This indicates the total carbon mass fraction contained in the mixed powder in its original state.

[0077] During system operation, various quality variable parameters are entered and calculated through online analytical instruments or periodic manual testing. The numerical fluctuations. When the carbon conversion rate is lower than the set threshold, the central control system increases the operating temperature of the core reaction zone by reverse fine-tuning the proportion of input oxygen, so that the reaction state tends to return to equilibrium and maintains the carbon conversion rate within the target range of not less than 98%.

[0078] Combined with appendix Figure 1 and Figure 2 This paper provides a detailed explanation of the changes and chemical synergistic reaction mechanism that occur after the mixed powder enters the core reaction zone of the fluidized bed gasifier in this embodiment.

[0079] When the mixture is in a high-temperature operating environment of 1200℃ to 1500℃, the internal components of the system undergo cross-phase fusion and chemical reconstruction, specifically encompassing the following multi-mechanism intertwined execution process: Liquid slag layer loading and inner wall corrosion protection process. The inherent ash content of a single biomass feedstock is typically between 1% and 5%, which is far below the minimum critical slag concentration required to maintain continuous operation of a fluidized bed gasifier. If biomass is directly gasified alone, the extremely thin ash content cannot form a continuous liquid film on the inner wall, and high-temperature radiation and corrosive syngas will directly damage the metal water-cooled walls or refractory lining of the fluidized bed gasifier. The system controls the proportion of coal gasification fine slag in the mixed powder, utilizing the high ash content of the fine slag itself to forcibly supplement the overall inorganic mineral content of the reaction system.

[0080] In the core reaction zone, the inorganic components in the fine slag co-melt with the biomass ash, forming a fluid liquid slag with suitable viscosity-temperature characteristics. This liquid slag continuously flows downwards along the inner wall of the fluidized bed gasifier, solidifying at the contact surface due to cooling from the inner wall, forming a tightly adhered and dynamically renewed liquid-solid composite slag layer. This composite solid slag layer acts as an isolation barrier, preventing the high-temperature gas flow from thermally eroding and chemically penetrating the heated surface material.

[0081] In-situ solid-phase capture and chemical transformation of alkali metals. Biomass structures are enriched with large amounts of alkali metals, specifically potassium and sodium, along with a certain proportion of chlorine. Under the high-temperature environment of a fluidized bed, these elements readily detach from the biomass matrix and undergo volatilization and sublimation, generating gaseous potassium chloride and sodium chloride. These highly corrosive gaseous alkali metal chlorides are the root cause of fouling, slagging, and high-temperature corrosion in downstream waste heat boiler tube bundles.

[0082] The coal gasification slag mixed in the system contains silicon dioxide and alumina with a total mass fraction of not less than 60%. At the surface of the liquid slag and at the gas-liquid interface, gaseous alkali metal chlorides undergo in-situ coordination reactions with the molten silicon-aluminum inorganic network. Potassium or sodium ions in the gas phase break some silicon-oxygen bonds or aluminum-oxygen bonds, embedding and solidifying within the interstitial spaces of aluminosilicate lattice, combining and transforming into a high-melting-point, low-volatility complex salt mineral crystalline phase. Its chemical form specifically manifests as high-melting-point aluminosilicate refractory minerals, such as potassium aluminosilicate or sodium aluminosilicate composite mineral phase structures like leucite, mullite, microcline, and feldspar.

[0083] The aforementioned in-situ chemical transformation from highly reactive gaseous molecules to highly stable solid crystals forcibly binds most of the free alkali metals in the reaction system to the liquid slag and discharges them with the bottom slag, thus eliminating the risk of corrosion and blockage in the subsequent waste heat recovery unit from the source of the material.

[0084] In this chemical co-curing process, the alkali metal solid phase retention rate parameter is introduced to quantitatively evaluate the system's ability to control corrosion at its source. Its calculation formula is defined as follows: ; in, This indicates the overall solid-phase retention rate of alkali metals in the system; This indicates the total mass of solid coarse slag after quenching the liquid slag discharged within a set period; This indicates the mass fraction of alkali metal oxides in solid coarse slag as detected by inductively coupled plasma atomic emission spectrometry. This indicates the total mass of mixed powder input to the system within the same period; This indicates the mass fraction of total alkali metal oxides initially carried in the mixed powder. The system adjusts the operating temperature of the core reaction zone to achieve this. The measured values ​​were maintained within the operating index range of no less than 85%.

[0085] Catalytic gasification degradation process of highly graphitized carbon residue. The carbon residue contained within the fine coal gasification slag, due to the severe high-temperature thermal shock experienced during the initial gasification process, exhibits a highly ordered layered arrangement of carbon microcrystals. This microscopic feature manifests as a strong tendency towards graphitization, leading to a reduction in active sites at the carbon atom edges and extremely inert chemical reactivity.

[0086] At this stage, the system utilizes the metal components released from biomass to alter the reaction kinetics. In the initial stage of rapid biomass pyrolysis and gasification, free alkali and alkaline earth metals, specifically potassium, sodium, calcium, and magnesium ions, released from within the biomass, are adsorbed onto the micropores of the fine slag residue surface through collision. These metal ions adsorbed on the carbon microcrystal surface act as electron transfer mediators for the carbon gasification reaction.

[0087] The intervention of metal ions directly weakens the resistance to the breaking of carbon-carbon covalent bonds in the residual carbon molecules, thus changing the original reaction pathway from a chemical kinetic perspective.

[0088] Through the surface catalytic mechanism of alkali metals and alkaline earth metals, the apparent activation energy required for the gasification reaction of residual carbon is reduced. Under this catalytic effect, even while maintaining the same absolute thermodynamic temperature of the reaction system, the chemical reaction rate constants for the conversion of inert residual carbon with water vapor and carbon dioxide into carbon monoxide and hydrogen can still exhibit an exponential increase.

[0089] This catalytic effect offsets the negative impact of high graphitization of fine slag residue carbon, improving the overall carbon conversion rate of the fluidized bed gasifier.

[0090] For the calculation principle of electron transfer orbit hybridization of specific metal ions at carbon atom lattice defects, those skilled in the art can use conventional quantum chemical density functional theory to model it. The calculation and verification methods are well-known in the field and will not be elaborated here.

[0091] See attached document Figure 2 With reference to the accompanying drawings, the internal structure and hardware composition of the waste heat recovery unit of the waste boiler in this embodiment will be described in detail.

[0092] The waste heat recovery unit of the total waste boiler is arranged with radiant waste boiler and convective waste boiler in sequence along the flow direction of crude syngas.

[0093] The radiant waste boiler is located directly below or adjacent to the side of the fluidized bed gasifier. Its shell is sealed to the syngas outlet of the fluidized bed gasifier via a high-temperature flange and expansion joint. The internal heat-absorbing components of the radiant waste boiler are specifically embodied in a water-cooled wall coil structure or a membrane water-cooled wall structure. For the calculation principles of the natural gas-water circulation and gas-liquid two-phase flow boiling heat transfer within the membrane water-cooled wall system, those skilled in the art can establish models based on the design standards of conventional power plant boilers or chemical waste boilers. The heat transfer mechanism is well-known in the field and will not be elaborated further here. A slag discharge guide port is provided at the bottom of the radiant waste boiler to guide unsolidified liquid slag into the slag discharge unit at the bottom.

[0094] The inlet of the convective waste heat boiler is connected to the exhaust of the radiant waste heat boiler via a transition flue. The internal heat exchange tube bundle of the convective waste heat boiler can be any one of a bare tube bundle, a spiral finned tube bundle, or a serpentine tube bundle. The exterior of the convective waste heat boiler shell is equipped with a soot removal device for removing ash accumulated on the tube surfaces; this device can be an acoustic soot blower, a shock wave soot blower, or a steam soot blower. The exhaust of the convective waste heat boiler is directly connected to the input of the syngas purification unit.

[0095] In the overall structural configuration of the waste heat recovery unit, the distribution of the heating area between the radiant and convective waste heat boilers directly determines the heat absorption matching degree of the waste heat recovery system to the gas produced by the front-end co-gasification. At the structural design level, the system comprehensively considers the matching relationship between the radiant heating surface area and average radiant heat flux density of the radiant waste heat boiler and the convective heat transfer area and overall heat transfer temperature difference of the convective waste heat boiler, and introduces a heat load distribution coefficient to define the scale ratio of the two waste heat boilers.

[0096] When constructing the specific dimensions of the waste heat recovery unit, the heat load distribution coefficient is forcibly limited to a value range of 1.2 to 2.5 by adjusting the core heat exchange area of ​​the two-stage waste heat boilers. This proportional configuration ensures that the radiant waste heat boiler has sufficient heat absorption margin to cope with the operating temperature fluctuations that may occur in the fluidized bed gasifier, while ensuring that the heat exchange tube bundle of the convective waste heat boiler will not suffer thermal shock and overheating damage due to insufficient cooling in the preceding stage.

[0097] Combined with appendix Figure 1 and Figure 2 The step-cooling process and the corresponding anti-corrosion and anti-clogging chemical mechanism implemented by the waste heat recovery unit of the waste boiler in this embodiment are described in detail.

[0098] The waste heat recovery unit of the waste boiler receives high-temperature crude products from the pre-reaction system and achieves energy recovery and gas-phase cooling through segmented heat exchange. For the hydrodynamic circulation and steam-water separation mechanism on the water side inside the heat exchange tube bundle, those skilled in the art can refer to conventional forced circulation or natural circulation boiler design specifications to construct the system. The boiling heat transfer process inside the tubes is well-known in the field and will not be elaborated upon here.

[0099] The cascade waste heat recovery process for crude syngas is divided into the following execution steps: High-temperature radiative cooling treatment. The crude syngas discharged from the top or side wall syngas outlet of the fluidized bed gasifier, carrying high-temperature sensible heat and some fly ash particles, directly enters the radiant waste boiler. At this point, the initial temperature of the crude syngas is between 1200℃ and 1500℃. Inside the cavity of the radiant waste boiler, the crude syngas transfers heat to the water-cooled wall tube bundles arranged around the perimeter through thermal radiation.

[0100] Inside the tubes, the desalination boiler water absorbs high-temperature heat and vaporizes to generate high-pressure or medium-pressure steam. After this stage of intense radiative cooling, the temperature of the crude syngas decreases. Operators control the temperature of the crude syngas at the exhaust port of the radiant waste boiler to between 600°C and 800°C by adjusting the working fluid circulation ratio within the water-cooled wall tubes. During the rapid cooling process across this temperature range, the water-cooled wall surface of the radiant waste boiler did not exhibit the severe fouling and slagging phenomena that are highly likely to occur in conventional high-alkali biomass gasification processes. This anti-fouling characteristic is directly attributable to the in-situ solidification mechanism of alkali metals implemented in the pre-co-reaction stage.

[0101] Because the coal gasification fine slag mixed in the gasifier has a large amount of silicon and aluminum mineral components inside, it has converted the volatile free alkali metals released by biomass into high melting point crystalline phases and firmly imprisoned them in the liquid bottom slag before discharge. This results in an extreme lack of gaseous alkali metal chloride molecules with fluxing effect in the material system that enters the radiant waste boiler with the crude syngas.

[0102] The solid fly ash particles carried out by the airflow have significantly higher ash deformation and softening temperatures than the operating temperature of the tube walls inside the radiant waste boiler due to the support of the internal silicon-aluminum skeleton. When the fly ash particles collide with the water-cooled wall surface, they maintain the characteristics of hard, dry particles and cannot form an initial ash deposition layer with adhesive elasticity on the heated metal surface.

[0103] Medium-temperature convective cooling treatment. The crude syngas, radiatively cooled to 600°C to 800°C, smoothly enters the convective waste heat boiler. Within this space, the crude syngas flows laterally or longitudinally through the densely packed heat exchange tube bundles inside the convective waste heat boiler. The residual medium-to-low temperature sensible heat of the crude syngas is transferred to the boiler feedwater or low-pressure steam medium inside the tubes via convective heat transfer.

[0104] By matching the pre-set heat exchange area of ​​the tube bundle with the internal working fluid flow rate, the temperature of the crude syngas output from the exhaust end of the convective waste heat boiler is finally stably controlled between 250℃ and 400℃.

[0105] Within the compact tube bundle flow section of the convective waste heat boiler, the fly ash particles entrained in the coarse syngas exhibit an extremely dry and loose powder morphology. As the dry dust travels with the airflow, it completely loses its mechanical ability to adhere to the tube wall and to bridge and agglomerate with each other, thus cutting off the boundary conditions for large-area ash accumulation, bridging, and channel blockage between the tube bundles.

[0106] The small amount of floating dust generated on the tube wall surface due to airflow eddies can be easily removed by high-energy acoustic waves or mechanical shock waves emitted by an external cleaning device. In addition, the absence of corrosive gaseous alkali metal chlorides in the crude syngas completely blocks the electrochemical and thermochemical reaction chain that causes high-temperature alkali-chlorine combined corrosion on the surface of the metal heat exchange tube, eliminating the risk of corrosion penetration of the metal matrix grain boundaries from the root and ensuring a long service life of the waste boiler heat exchange tubes.

[0107] During the execution of the aforementioned cascade cooling process, the system calculates the net enthalpy increment absorbed by the steam output from the waste heat recovery unit of the total waste boiler and compares it with the total sensible heat released by the crude syngas within the inlet and outlet temperature drop range. This sensible heat recovery rate parameter is then introduced to quantify and calibrate the thermal energy conversion efficiency. By precisely adjusting the process cooling curve, the system maintains the actual index of this comprehensive sensible heat recovery rate within a high design expectation range, thereby achieving highly efficient waste heat recovery.

[0108] See attached document Figure 2 With reference to the accompanying drawings, the high-temperature dry purification process and hardware configuration executed by the syngas purification unit in this embodiment will be described in detail.

[0109] The syngas purification unit is configured as a high-temperature dry dust removal device. For the core internal filter element, either a sintered metal porous cartridge dust collector or a high-temperature ceramic tube filter is selected. The microporous sieving and interception mechanism inside the filter element and the external pulse-jet cleaning structure can be configured according to conventional gas-solid separation design standards by those skilled in the art. The filtration resistance loss and the reverse stripping principle of the cleaning airflow are well-known technologies in the field and will not be elaborated further here.

[0110] For the crude syngas after step-cooling, the dust removal and purification process is specifically divided into the following steps: Constant-temperature gas is directly introduced. The crude syngas discharged from the convective waste boiler at the tail end of the waste heat recovery unit is directly introduced into the inlet chamber of the syngas purification unit through an insulated pipe. During the introduction process, the temperature of the crude syngas is maintained between 250℃ and 400℃, and the operating pressure inside the system is linked to the pressure of the front-end fluidized bed gasifier. Directly introducing the mixed gas in the high-temperature range avoids the quench water bath process required by traditional water-washing dust removal processes, thus maintaining the overall thermodynamic energy level of the system.

[0111] Dry gas-solid microscopic separation occurs. The crude syngas carrying dust particles permeates the internal porous filter element under the pressure difference. Since the in-situ consolidation of alkali metals has already been completed in the upstream core reaction zone, there are no longer easily condensable gaseous alkali metal chlorides in the crude syngas. Simultaneously, the gas operating temperature is much higher than the dew point temperature of water vapor in the syngas.

[0112] Therefore, the fly ash particles carried by the airflow have no liquid water film or semi-molten salts adhering to their surface, exhibiting purely dry, rigid particle characteristics. When these dry fly ash particles come into contact with the filter element surface, they are intercepted by the filter element's own micropores, accumulating to form a loose dust initial layer with extremely high air permeability. The gaseous medium smoothly penetrates the filter element wall through the pores and enters the internal clean air chamber, thus achieving highly efficient separation of the gas and solid phases at the microscopic level.

[0113] Sensible heat retention and waterless ash discharge. After the clean phase gas, from which solid impurities have been removed, is collected, it is converted into clean syngas and output from the exhaust end of the syngas purification unit. This clean syngas itself still carries sensible heat of 250°C to 400°C, and after being output, it can be directly incorporated into the downstream medium-high temperature carbon monoxide conversion section or methanation reactor, eliminating the additional heat energy consumption caused by secondary heating of the gas.

[0114] During this period, the thickness of the dry dust layer adhering to the outer surface of the filter element gradually increases. By periodically opening the backflush valve and injecting high-pressure inert gas, the dust layer is peeled off using a transient reverse expansion airflow. The falling dry ash collects in the ash hopper at the bottom and is discharged outside the system. The entire purification process is completely free from the involvement of liquid water media, avoiding the generation of phenol-cyanide-containing black water in the gasification process, thereby reducing the construction scale of the supporting wastewater treatment system.

[0115] When evaluating the operating status of a high-temperature dry dust removal unit, the mass flow rate of initial fly ash entrained in the crude syngas before entering the purification unit is compared with the mass flow rate of residual solid particles in the clean syngas exiting the exhaust end. This comparison introduces a mass dust removal efficiency index for dynamic monitoring. Under continuous and stable operating conditions, based on the set interception accuracy of the porous filter element, the mass dust removal efficiency is controlled to remain within the index limit of no less than 99.9% to ensure thorough gas-solid separation.

[0116] The structural composition of the slag discharge unit and the process of discharging liquid slag in this embodiment are described in detail.

[0117] The receiving end of the slag discharge unit is directly connected to the slag discharge port at the bottom of the fluidized bed gasifier or the slag discharge guide port at the bottom of the radiant waste heat recovery unit in the total waste heat recovery unit. The internal hardware of the slag discharge unit typically includes a vertically arranged quench water bath slag pool, a slag breaking device, and a slag collection device. The slag collection device is selected according to the system operating pressure of the fluidized bed gasifier. When the system is under pressure, the slag collection device uses a program-controlled slag-locking valve assembly and a pressure-resistant slag-locking hopper; when the system is under normal pressure, the slag collection device uses a scraper slag remover or a spiral slag discharger. Regarding the toothed roller interlaced shearing and mechanical crushing structure inside the slag breaking device, those skilled in the art can select and configure it based on conventional solid material crushing equipment. The principle of mechanical extrusion and shearing to break large slag pieces is well-known in the field and will not be elaborated here.

[0118] The slag removal process for the inorganic byproducts generated in the core reaction zone is specifically divided into the following steps: The molten slag falls under gravity and is then quenched in a water bath. Under the core operating temperature of the fluidized bed gasifier, biomass ash and silica-alumina minerals in the coal gasification slag co-melt to form liquid slag. This liquid slag detaches from the dripping lip at the bottom of the radiant waste boiler or gasifier under gravity and continuously falls into the quenched water bath slag pool.

[0119] Upon contact with cooling water, the liquid slag, which is in a high-temperature phase, undergoes a violent heat exchange. The temperature of the liquid slag rapidly exceeds its crystallization point, and it does not have time to form a regular mineral crystal structure, thus transforming into a glassy coarse slag in an amorphous state.

[0120] During this phase transition, the alkali metal components that were transformed into aluminosilicate composite minerals in the early gasification reaction stage are completely encapsulated and imprisoned within a dense glassy inorganic network structure, losing their chemical activity to leach out and release into the external environment.

[0121] In the aforementioned water bath quenching cooling operation, some of the cooling water absorbs the sensible heat of the high-temperature molten slag and vaporizes. By calculating the total sensible heat enthalpy drop released by the liquid slag falling into the slag pool per unit time during the cooling process, and combining this with the latent heat of vaporization at the water bath equilibrium temperature, the system introduces a quenching vaporization consumption parameter to calculate the water balance state of the slag pool system. By monitoring the fluctuations in this vaporization consumption in real time, the control system synchronously replenishes the slag pool with the same mass of low-temperature process water, thereby maintaining a dynamically constant liquid level.

[0122] Mechanical crushing and slag-water separation. The glassy coarse slag generated by rapid cooling exhibits an irregular granular shape. Some of the coarse slag aggregates and agglomerates during the cooling process, forming large slag blocks. The material mixed with water and coarse slag flows through the crushing device at the bottom.

[0123] The slag crushing device uses rotating crushing teeth to forcibly crush large pieces of slag that exceed size limits, ensuring that the falling solid particles can pass smoothly through the flow section of valves or conveyor belts. The crushed coarse slag passes through the aqueous medium under gravity and settles and accumulates at the bottom of the slag collection device.

[0124] System depressurization and solid phase discharge. When the system is in the aforementioned high-pressure operating environment, the slag discharge operation is performed intermittently. The settled coarse slag accumulates in the pressure-resistant slag hopper. The control system closes the slag inlet valve at the top of the slag hopper according to a set time cycle, cutting off its connection with the quench water bath slag pool. Subsequently, the pressure relief valve is opened to gradually reduce the pressure inside the slag hopper to ambient atmospheric pressure.

[0125] After the depressurization operation is completed, the bottom slag discharge valve is opened, and the solid coarse slag, along with some stagnant water, is discharged into the external slag pool or slag transport vehicle. After emptying, the slag hopper is repressurized and the top slag inlet valve is opened to begin the next slag discharge cycle.

[0126] The discharged glassy coarse slag, due to its good stability and extremely low heavy metal leaching rate, can be directly sold as an inert admixture for the preparation of building materials or cement clinker, thus completing the resource-based disposal of solid waste.

[0127] As another embodiment of this application, a semi-waste boiler waste heat recovery unit is provided to replace the aforementioned full-waste boiler waste heat recovery unit for the heat recovery and cooling stage at the end of the system. In the overall process flow of the gasification system, the semi-waste boiler waste heat recovery unit and the full-waste boiler waste heat recovery unit constitute an equivalent substitution relationship in terms of technical solutions.

[0128] The internal hardware of this semi-waste boiler waste heat recovery unit consists of a radiant waste boiler and a water-cooled quench chamber connected in sequence. The structure of the radiant waste boiler is consistent with the aforementioned embodiment, retaining the water-cooled wall coil or membrane water-cooled wall structure. The water-cooled quench chamber, as an equivalent replacement structure for the convective waste boiler, has a quench ring, downcomer, and bottom quench water bath arranged from top to bottom inside.

[0129] Regarding the water film formation in the quenching ring inside the water quenching chamber and the gas-liquid two-phase heat and mass transfer mechanism in the downcomer, those skilled in the art can refer to the conventional coal chemical quenching process for pipeline design. The fluid dynamics and thermodynamic phase change principles are well-known technologies in this field and will not be elaborated here.

[0130] This alternative solution has clearly defined industrial applicability boundaries and application scenarios. When the downstream section of the gasification system is connected to ammonia synthesis, hydrogen production, or methanol synthesis processes, the input synthesis gas requires a specific hydrogen-to-carbon ratio. To increase the hydrogen content, a carbon monoxide-water-gas shift reaction section must be installed downstream. This shift reaction consumes a large amount of water vapor.

[0131] The semi-waste boiler waste heat recovery unit utilizes water quenching to forcibly cool the crude syngas while directly mixing a large amount of evaporated water into the gas phase medium. This satisfies the downstream shift reaction's inlet gas boundary requirements for the water-to-vapor ratio, eliminating the need for additional high-pressure steam injection in the shift section.

[0132] The process flow implemented using this semi-waste boiler waste heat recovery unit is divided into the following specific steps: High-temperature radiant heat recovery. The crude syngas carrying high-temperature sensible heat is discharged from the fluidized bed gasifier 40 and directly enters the radiant waste boiler. The crude syngas undergoes thermal radiation cooling in this area, transferring some of the high-grade heat energy to the water-cooled walls to generate high-pressure steam.

[0133] By controlling the water-side heat load, the temperature of the crude syngas leaving the radiant waste boiler is reduced to 600°C to 1000°C. This step avoids the huge heat loss caused by directly quenching 1500°C high-temperature gas while preserving the system's ability to produce high-pressure steam.

[0134] Direct contact water quenching and gas-phase humidification. The crude syngas, after initial cooling, passes through a downcomer connected to the neck and enters the water quench chamber. A quenching ring positioned at the top of the downcomer continuously sprays high-pressure cooling water. Intense interphase friction and direct contact heat transfer occur between the gas and liquid phases within the confined space of the downcomer.

[0135] The sensible heat of the crude syngas causes a large amount of liquid water to vaporize, resulting in a sharp drop in its own temperature. Within this operating range, the outlet temperature at the bottom of the water quench chamber is controlled between 200°C and 250°C.

[0136] In the water quenching and humidification process, the system uses the total sensible heat released by the dry crude syngas within a set temperature drop range, combined with the enthalpy difference of the latent heat of vaporization required for the quenching water vaporization process, to introduce a gas-phase humidification parameter for dynamically calculating the mass of water transferred into the syngas. This process controls the proportion of water evaporation and mixing, ensuring that the gas-phase humidification meets the requirements of subsequent chemical synthesis.

[0137] Gas-liquid separation and coarse slag collection. Wet-based crude syngas, carrying a large amount of water droplets and residual fly ash particles, rushes out from the bottom of the downcomer and impacts the surface of the bottom quench water bath at high speed. Under the combined action of inertial force and surface tension, the solid fly ash particles and large-diameter water droplets entrained in the gas phase are forcibly separated and collected by the aqueous phase. The saturated wet-based syngas, after dehydration by deflection, is output from the exhaust port above the water quench chamber and sent to subsequent processing stages.

[0138] The coarse slag particles that fall to the bottom settle and accumulate, and are eventually discharged from the system through the connected slag collection device. Through the above steps, the semi-waste boiler solution completes the wet primary purification of dust while adjusting the composition of the syngas.

[0139] As another embodiment of this application, a wet purification unit is provided as a technical alternative to the aforementioned high-temperature dry dust removal unit, or as a downstream deep purification derivative configuration for the purification stage of syngas at the tail end of the gasification system.

[0140] In specific industrial applications, when the downstream of a gasification system is connected to a specific catalyst bed with stringent restrictions on impurities, it is necessary to perform extreme removal of trace amounts of acidic gases.

[0141] The core hardware of this wet scrubbing unit specifically includes a Venturi scrubber and a water washing tower connected in series. For the fluid dynamics design of the liquid distributor, the distribution structure of the trays or packing, and the gas-liquid countercurrent contact mechanism inside the water washing tower, those skilled in the art can refer to conventional chemical separation engineering specifications to construct the system. The physicochemical mechanisms of gas-liquid two-phase mass transfer and momentum transfer are well-known technologies in this field and will not be elaborated upon here.

[0142] The synthesis gas entering the wet purification unit contains residual fine dust and trace amounts of hydrogen chloride gas. The system performs the following deep purification and dechlorination operations on this gas stream: Washing, cooling, and inertial trapping. The crude syngas is introduced into the constricted flow channel of the Venturi scrubber, where the flow cross-section decreases sharply, increasing the airflow velocity. In the Venturi throat region, the high-speed airflow collides violently with the laterally injected wash water. The enormous relative velocity difference between the gas and liquid phases directly tears apart the surface tension of the liquid, forming a highly atomized cluster of fine droplets.

[0143] Free dust particles carried in the syngas break through the fluid streamlines under the action of inertial forces, collide with and embed themselves inside the liquid droplets. After the fine dust particles are encapsulated by the liquid film, their mass increases significantly, thereby losing the kinetic conditions for continued suspension and migration with the airflow, thus achieving the primary interception of solid impurities.

[0144] Deep dechlorination and chemical absorption. The gas-liquid mixture, after washing and cooling, flows into the bottom of the water washing tower and undergoes preliminary separation. The gas turns upward and passes through the packing layer inside the water washing tower at a uniform speed. An absorbent liquid containing a weakly alkaline substance is continuously sprayed downward from the top of the water washing tower. The specific chemical composition of this alkaline substance is selected from sodium hydroxide or sodium carbonate.

[0145] On the surface of the packing material with a complex geometry, the liquid medium spreads to form a continuous and extremely thin liquid film, providing a huge contact area for the gas and liquid phases. The trace amounts of hydrogen chloride molecules remaining in the syngas penetrate the boundary layer on the gas side and dissolve in the liquid film due to the concentration gradient difference. They then rapidly undergo an irreversible neutralization reaction with the alkaline free ions in the liquid phase, transforming into sodium chloride salts that are stable in the liquid phase.

[0146] In the above-mentioned coupled process of gas-liquid mass transfer and acid-base neutralization, based on the overall gas-phase mass transfer coefficient, the gas-liquid contact surface area provided by the packing configuration, and the molar concentration gradient difference of hydrogen chloride at the gas-liquid interface, the system introduces the hydrogen chloride mass transfer absorption rate parameter to quantitatively define the reaction intensity of the scrubbing tower.

[0147] During process operation, by monitoring and maintaining the pH of the absorbent in the alkaline range, the critical molar fraction of hydrogen chloride at the gas-liquid equilibrium interface is forced to approach zero. Simultaneously, the circulation pump flow rate is adjusted to increase the contact surface area, ensuring the overall mass transfer and absorption rate remains within the designed high range.

[0148] Gas-liquid separation and ultra-clean gas output. The syngas, having undergone deep dechlorination, continues to rise, passing through a wire mesh demister or baffle plate dehydrator located at the top of the water washing tower. This mechanical structure intercepts and collects tiny droplets entrained in the gas flow, causing them to flow back into the tower. The volume concentration of hydrogen chloride inside the output deep-purified syngas is reduced and stably limited to below 0.5 ppm.

[0149] This extreme purification index breaks the material transport chain that causes chemical adsorption and poisoning deactivation of downstream methanol synthesis or Fischer-Tropsch synthesis catalysts by hydrogen chloride molecules. The washing waste liquid generated by the reaction, containing free inorganic salts and suspended solid particles, is led out from the drain port at the bottom of the water washing tower and sent to a separate wastewater treatment module for sedimentation separation and salt concentration.

[0150] Combined with the appendix Figure 2 This paper provides a detailed description of the hardware connection topology and operating process of the system extension implementation scheme of this application, namely the fine slag and fly ash recycling and regasification scheme.

[0151] In this embodiment, a solid material circulation pipeline is configured between the dust discharge outlet of the syngas purification unit and the material input outlet of the front-end mixing and pulverizing unit. Inevitably, trace amounts of residual carbon that has not undergone complete gasification are carried in the dry fly ash intercepted by the porous filter element in the syngas purification section. By establishing a circulation path, this portion of fly ash rich in residual carbon is reintroduced into the core reaction zone to maximize the overall carbon conversion rate of the system.

[0152] For the conveying power unit configured inside the circulating conveying pipeline, any one of the following can be selected: high-pressure pneumatic conveying pump, tubular chain conveyor, or closed screw conveyor. For the calculation of pressure drop in the gas-solid two-phase flow inside the conveying pipeline network and the design of the critical flow velocity to prevent particle deposition, those skilled in the art can establish a physical model based on conventional powder engineering manuals. The pneumatic conveying dynamics principle is a well-known technology in this field and will not be elaborated upon here.

[0153] The specific process flow for implementing the fly ash recycling and regasification scheme is divided into the following operation steps: Collection and steady-flow conveying of circulating materials. High-temperature dry fly ash discharged from the bottom ash collection hopper of the syngas purification unit is depressurized from high pressure to normal pressure via a program-controlled ash-locking valve assembly. The depressurized fly ash falls into a circulating delivery tank, where nitrogen or carbon dioxide is used as the carrier gas. It is then pressurized and conveyed to a circulating buffer silo added above the mixing and pulverizing unit. During the circulating buffering and proportioning process, the circulating fly ash is cooled by the inert carrier gas environment or by natural heat dissipation through the pipeline network, preventing premature pyrolysis of fresh biomass within the mixing and pulverizing unit.

[0154] During transportation, the external heating device of the pipeline maintains the temperature of the fly ash body to prevent condensation and moisture absorption, which would lead to deterioration of its rheological properties.

[0155] Multi-source materials are dynamically proportioned online. Fly ash temporarily stored in the circulating buffer silo is discharged through the rotary feed valve at the bottom. Fresh biomass feedstock, pre-treated coal gasification fine slag, and circulating fly ash are simultaneously fed into the proportioning and weighing device.

[0156] The central control system receives weighing sensor signals from various materials and adjusts the feeding speed of different feeders. In this step, the system treats the recycled material as an independent raw material with high ash content and low carbon equivalent for comprehensive calculation.

[0157] In the proportioning calculation logic of multi-source materials, the circulating residual carbon equivalent ratio parameter is introduced to constrain the scale of reflux material, and its calculation formula is defined as: ; in, This indicates the circulating residual carbon equivalent ratio under steady-state operating conditions; This represents the total mass of fly ash returned to the mixing and pulverizing unit via the circulation pipeline within a unit time period; This indicates the mass fraction of residual carbon in the circulating fly ash as determined by sampling and testing. This indicates the quality of fresh biomass introduced into the system within the same time period; This indicates the mass fraction of carbon contained in fresh biomass; This indicates the quality of fresh coal gasification slag added within the corresponding cycle; This indicates the mass fraction of carbon in the fine slag from fresh coal gasification.

[0158] By fine-tuning the opening of the discharge valve at the bottom, the control system will... The actual value is limited to the range of 0.02 to 0.08. This boundary limit ensures the recovery of residual char while avoiding the vicious accumulation and dead cycle of a large amount of ineffective inorganic ash inside the gasifier.

[0159] Mixing and remodeling with secondary catalytic gasification. The mixture, collected in a specific ratio, enters the main grinding equipment for crushing and grinding. During this process, the recycled fly ash particles rub against the fresh biomass particles, forming dense particle agglomerates.

[0160] Subsequently, the mixed powder was injected into the fluidized bed gasifier. After the previous thermal shock, the microstructure of the residual char in the circulating fly ash had partially shrunk and collapsed. When placed again in a high-temperature environment of 1200°C to 1500°C, free potassium, sodium, and other alkali metal ions released from the rapid pyrolysis of fresh biomass re-permeated and adsorbed onto the surface defect sites of this portion of the residual char. This in-situ alkali metal catalytic environment lowered the apparent activation energy of the highly graphitized residual char.

[0161] The remaining inert carbon residue is forcibly degraded into carbon monoxide gas under the synergistic effect of water vapor and carbon dioxide. Simultaneously, the dominant silica-alumina inorganic mineral framework in the circulating fly ash melts upon heating in the furnace inner wall region, again participating in the construction of the dynamic liquid slag layer, and is ultimately captured and discharged by the slag discharge unit as glassy bottom slag. Through this reconstruction of material flow, the system completely achieves closed-loop disposal of carbonaceous waste within the system.

[0162] See attached document Figure 2 This paper provides a detailed description of another extended implementation of this application, namely, omitting the gas-solid separation and deep purification steps and directly applying the crude syngas to the downstream thermal equipment for direct heat supply.

[0163] In this specific application scenario, the syngas purification unit is removed from the overall system connection topology. The exhaust end of the waste heat recovery unit is directly connected to the terminal gas-consuming equipment via a high-temperature insulated gas transmission pipeline network. This terminal gas-consuming equipment is specifically a gas-fired steam boiler, a cement rotary kiln, or a metallurgical industrial heating furnace.

[0164] For the high-temperature gas expansion compensation and thermodynamic pipeline stress calculation inside the pipeline network, those skilled in the art can perform modeling and analysis based on conventional industrial pipeline design specifications. The thermal stress release mechanism and compensator selection are well-known technologies in this field and will not be elaborated here.

[0165] The process for direct utilization of crude syngas is divided into the following steps: The crude syngas is supplied directly under pressure and at a constant temperature. The crude syngas output from the convective waste heat recovery unit within the total waste heat recovery unit has a body temperature between 250°C and 400°C, and dry fly ash particles are uniformly suspended in the gas phase. This multiphase flow mixed gas is directly pressurized to the terminal gas-consuming equipment without passing through any porous media filtration or liquid phase scrubbing resistance elements, maintaining its original operating pressure. Eliminating the filtration and scrubbing steps reduces the overall aerodynamic resistance loss of the system and completely preserves the original sensible heat level of the crude syngas.

[0166] Dust-rich gas is combusted in situ and co-treated with dust. Rough syngas carrying dry fly ash particles is injected into the combustion chamber of the terminal gas-consuming equipment. The gas burners inside the combustion chamber mix and ignite the combustible components of the rough syngas, such as carbon monoxide, hydrogen, and small-molecule hydrocarbons, with the supplied air, releasing chemical heat. In this combustion reaction zone, the entrained fly ash particles undergo secondary high-temperature heating.

[0167] Because the free alkali metals in biomass feedstock, which are highly susceptible to contamination, are chemically solidified in situ by the silicon and aluminum components in the fine coal gasification slag inside the front-end gasifier and discharged from the system with the liquid bottom ash, the fly ash particles entering the combustion chamber exhibit a high-melting-point pure silicon and aluminum oxide skeleton structure. This hard, dry fly ash does not possess the characteristics of high-temperature softening or adhesion to heated surfaces, and will not accumulate slag when passing through the heat exchange zone of the terminal gas-consuming equipment. The dust particles are ultimately discharged with the combustion exhaust gas and are uniformly intercepted and disposed of by the conventional flue gas dust removal device standardly equipped at the tail end of the equipment.

[0168] In the energy accounting of this direct utilization scenario, by comprehensively superimposing the low chemical calorific value of the crude syngas itself, the total sensible heat carried by the gas phase, and the additional chemical heat released by the oxidation and combustion of the ungasified carbon substances remaining in the fly ash, the comprehensive thermal energy output flow rate parameter of the crude syngas is introduced to quantify the total energy scale transferred by the gasification system to the terminal equipment.

[0169] By constructing a process path for direct delivery and combustion utilization, the heat enthalpy dissipation caused by wet purification and the pressure drop caused by dry filtration are completely avoided. This allows the actual calculated value of the comprehensive thermal energy output flow rate to reach the theoretical extreme value under the same feed load conditions, greatly improving the overall macroscopic energy conversion and utilization efficiency of the system.

[0170] Specific application examples: Raw material parameter settings: The biomass raw material is crop straw (corn straw). The initial mass moisture content was 18%, the dry basis ash content was 6.5%, and the alkali metal oxides (potassium and sodium oxides) in the ash content was 28%.

[0171] The raw material for coal gasification fine slag is solid waste fine slag discharged from the fluidized bed gasification of a coal chemical enterprise. Its initial mass moisture content is 45%, the total mass fraction of silica and alumina on a dry basis is 62%, and the mass fraction of residual carbon is 25%.

[0172] Pretreatment and milling: Biomass pretreatment unit: Corn stalks are crushed to no more than 10mm and sent to a drum dryer to dehydrate to a moisture content of 12%; then they are sent to a rotary roasting oven and roasted at 250℃ for 30 minutes. Roasting removes some volatile chlorides and increases the crispness of the raw material.

[0173] Fine slag pretreatment unit: The coal gasification fine slag is dehydrated to a moisture content of 4% by a disc continuous dryer and then fed into a ball mill for pre-grinding to a particle size of no more than 0.1 mm.

[0174] Mixed grinding unit: The feed mass ratio of biomass to coal gasification slag is set at 100:20. The two sets of raw materials are jointly ground and homogenized in a vertical roller mill. The particle size of the mixed powder is controlled to be no greater than 0.1 mm, and it is stored in a mixed silo for later use.

[0175] Synergistic gasification reaction: High-pressure carbon dioxide gas is used as a dense-phase conveying medium to pressurize the mixed powder to the top burner of the fluidized bed gasifier. Simultaneously, 95% pure oxygen and superheated steam are input as gasifying agents. The feed load is adjusted, and the oxygen-to-carbon ratio of the gasifying agent is set to 0.35. The operating pressure of the fluidized bed gasifier is maintained at 4.0 MPa, and the operating temperature of the core reaction zone is controlled at 1350℃.

[0176] The average residence time of the material in the furnace was set to 4.5 seconds. Under these conditions, the fine slag containing silica-alumina minerals co-melted with the biomass ash, forming a liquid slag layer on the furnace wall. This process transformed the free alkali metals in situ into a potassium / sodium aluminosilicate composite crystalline phase, which was then discharged with the slag.

[0177] Waste heat recovery and purification: The crude syngas at 1350℃ enters the waste heat recovery unit of the waste heat recovery unit. First, heat radiation exchange occurs in the radiant waste heat recovery unit, producing 5.0MPa high-pressure steam, and the exhaust temperature drops to 750℃; then it enters the convective waste heat recovery unit, where it is laterally flushed by the bare tube bundle, producing low-pressure steam, and the exhaust temperature further drops to 320℃.

[0178] High-temperature crude syngas at 320℃ is directly fed into the syngas purification unit equipped with a high-temperature ceramic filter tube. Fly ash particles are separated under constant-temperature dry conditions, and clean syngas at 315℃ is output to the downstream process. The slag removal unit quenches the liquid slag at the bottom in a water bath, converting it into glassy coarse slag, and then discharges it.

[0179] Experimental verification and effect comparison: To verify the technical effect of this application, three process conditions were set for parallel operation comparison test (each continuous operation for 120 hours).

[0180] Experimental Group A (this application): Biomass + 20% coal gasification fine slag, total waste boiler cooling + dry dust removal.

[0181] Comparative Example B (Conventional Process): Single biomass gasification, without fine slag mixing. Due to the inability to control alkali metal volatilization, downstream processes can only use water quenching to prevent waste heat boiler corrosion.

[0182] Comparative Example C (Additive Process): Biomass + 10% purchased kaolin additive, total waste boiler cooling + dry dust removal.

[0183] The results of the data comparison are shown in the table below:

[0184] in conclusion: like Figure 3 As shown in the figure, the experimental effect comparison chart of the biomass co-gasification process provided in this application displays the percentage performance indicators through a grayscale bar chart on the left Y-axis, and the economic cost parameters through a solid line with square markers on the right Y-axis. Through intuitive data comparison, the technical advantages of experimental group A of this application are specifically reflected in the following three aspects: As attached Figure 3 As shown in the light gray columnar structure, in Comparative Example B, over 80% of the alkali metals from the single biomass gasification process enter the crude syngas, resulting in a very low solids retention rate of only 18.2%, making downstream equipment highly susceptible to high-temperature fouling and corrosion. Experimental Group A of this application, through in-situ reaction of fine slag, increases the alkali metal solids retention rate to 88.5%.

[0185] Meanwhile, the pure black broken line marked with squares in the figure represents the cost of the added curing agent, which shows that although Comparative Example C can also achieve a high curing effect (85.1%), it must bear the cost of kaolin additives, which is as high as 180 yuan / ton. This application (Experimental Group A) achieved a curing effect comparable to or even slightly better than high-cost solutions at zero cost, cutting off the material basis for contamination and corrosion of the heated surface, demonstrating excellent technical advancement and economic feasibility.

[0186] Apart from Figure 3Beyond the explicit macroscopic indicators shown, the microscopic mechanisms of the system's internal chemical reactions have also been optimized. The residual carbon within the fine coal gasification slag is typically an extremely difficult-to-react inert substance. However, in the co-gasification system of this application, alkali metal ions released during the initial rapid pyrolysis of biomass briefly penetrate the pores of the residual carbon and act as electron transfer mediators before final solidification. Thanks to this, the measured carbon conversion rate of the system reached 98.8%, which did not decrease despite the addition of a large proportion of high-ash, highly inert fine slag, demonstrating that the alkali metals in biomass play a clear catalytic gasification role in the degradation of the residual carbon in the fine slag.

[0187] Reflected in the appendix Figure 3 On the dark gray columnar surface, the gaseous escape of alkali metals was suppressed. Experimental group A directly and safely activated the waste heat recovery unit of the entire waste boiler, resulting in a comprehensive thermal efficiency of 86.2%. Compared to control group B, which was forced to use water quenching due to corrosion prevention requirements, resulting in a large amount of high-temperature sensible heat dissipation, and whose dark gray columnar surface efficiency was only 62.4%, experimental group A achieved a qualitative leap in overall energy conversion efficiency. Even compared to control group C (83.5%), which used kaolin, experimental group A achieved the highest heat recovery benefit thanks to the superior thermodynamic synergistic effect of the dual-source solid waste materials.

Claims

1. A method for co-gasification of biomass and coal gasification fine slag, characterized in that, Includes the following steps: Biomass raw materials are fed into a biomass pretreatment unit for crushing and drying, or for crushing, drying and baking, to generate pretreated biomass raw materials. Simultaneously, the coal gasification fine slag is sent to the fine slag pretreatment unit for drying, dehydration and pulverization to generate pretreated coal gasification fine slag. The pretreated biomass raw material and the pretreated coal gasification fine slag are fed into a mixing and grinding unit for mixing and grinding to generate mixed powder. The mixed powder and gasifying agent are simultaneously injected into the fluidized bed gasifier, where a synergistic gasification reaction occurs. During this reaction, the alkali metals and alkaline earth metals in the pretreated biomass feedstock come into contact with the residual carbon in the pretreated coal gasification slag and act as electron transfer mediators to promote the catalytic gasification reaction of the residual carbon. Simultaneously, the gaseous alkali metal chlorides or free potassium and sodium ions released from the pretreated biomass raw materials undergo in-situ coordination and bonding reactions with the silica and alumina in the pretreated coal gasification fine slag. The in-situ bonding transforms into a chemical substance in the form of a high-melting-point aluminosilicate complex salt mineral crystalline phase. The generated complex salt mineral crystalline phase adheres to the wall of the fluidized bed gasifier to form a slag layer, while the remaining unattached reactants gather to form liquid slag and crude syngas. The liquid slag is discharged into the slag discharge unit for quenching, generating solid coarse slag which is then discharged from the system. The crude syngas is sent to the waste heat recovery unit of the waste boiler for step cooling and sensible heat recovery to generate cooled crude syngas. The cooled crude syngas is sent to a syngas purification unit for separation and dust removal, and clean syngas is output.

2. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, When the biomass pretreatment unit crushes, dries, and bakes the biomass raw material to generate the pretreated biomass raw material, the specific process includes: The biomass raw material is fed into the crushing device inside the biomass pretreatment unit for crushing and processing to generate biomass pellets. The biomass pellets are fed into the drying device inside the biomass pretreatment unit for drying to remove moisture and generate dry biomass pellets. The dried biomass pellets are fed into a baking device inside the biomass pretreatment unit for baking to generate the pretreated biomass raw material.

3. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, The coal gasification fine slag is fed into the fine slag pretreatment unit for drying, dehydration, and pulverization to generate the pretreated coal gasification fine slag, including: The coal gasification fine slag is fed into the fine slag drying device inside the fine slag pretreatment unit for fine slag drying and dehydration treatment to generate dried fine slag. The dried fine slag is fed into the fine slag pulverizing device inside the fine slag pretreatment unit for fine slag pre-grinding and pulverizing treatment to generate the pretreated coal gasification fine slag.

4. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, The pretreated biomass raw material and the pretreated coal gasification fine slag are fed into the mixing and grinding unit for mixing and grinding to generate the mixed powder, comprising: The pretreated biomass raw materials and the pretreated coal gasification fine slag are simultaneously fed into the proportioning and weighing device inside the mixing and pulverizing unit for online proportioning and feeding, generating a mixture of materials gathered according to a preset mass ratio. The mixture of materials gathered according to a preset mass ratio is fed into the main grinding equipment inside the mixing and powdering unit for joint grinding and homogenization, so that the two phases are uniformly dispersed and mixed at the micro-particle level to generate the mixed powder.

5. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, The mixed powder and the gasifying agent are simultaneously injected into the interior of the fluidized bed gasifier, including: The gasifying agent is generated by mixing high-purity oxygen and superheated steam. Using carrier gas as the transport medium, the mixed powder and the carrier gas form a dense gas-solid two-phase flow and are fed into the process burner of the fluidized bed gasifier, while the gasifying agent is introduced into the process burner. The mixed powder and the gasifying agent are simultaneously injected into the high-temperature furnace space inside the fluidized bed gasifier through the process burner.

6. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, The synergistic gasification reaction process occurring inside the fluidized bed gasifier is specifically as follows: Under the high-temperature environment generated by the synergistic gasification reaction, the alkali metals and alkaline earth metals in the pretreated biomass raw material precipitate out and react with the residual carbon in the pretreated coal gasification fine slag before being solidified. The gaseous alkali metal chlorides or free potassium and sodium ions after the gasification reaction occur, and the silica and alumina in the pretreated coal gasification fine slag undergo an in-situ coordination reaction at high temperature, combining and transforming into a complex salt mineral crystalline phase. A portion of the complex salt mineral crystalline phase adheres to the wall of the fluidized bed gasifier to form the slag layer, while the remaining complex salt mineral crystalline phase converges and integrates into the interior of the liquid slag, thereby confining the alkali metal within the liquid slag and completing its solidification.

7. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, The liquid slag is discharged into the slag discharge unit for quenching to generate the solid coarse slag, which is then discharged out of the system, including: The liquid slag is discharged through the slag discharge port at the bottom of the fluidized bed gasifier into the quench water bath slag pool inside the slag discharge unit; The liquid slag comes into contact with cooling water inside the quench water bath slag pool and undergoes heat exchange, and the liquid slag cools down to form the glassy solid coarse slag; The solid coarse slag is discharged out of the system through the slag collection device at the bottom of the slag discharge unit.

8. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, The crude syngas is fed into the waste heat recovery unit of the total waste boiler for staged cooling and sensible heat recovery to generate the cooled crude syngas, including: The crude syngas is fed into the radiant waste boiler inside the waste heat recovery unit of the waste boiler for high-temperature radiant cooling treatment. The high-temperature sensible heat carried by the crude syngas is transferred to the desalination boiler water to generate high-pressure or medium-pressure steam, and at the same time, crude syngas that has been radiantly cooled is generated. The radiatively cooled crude syngas is fed into the convective waste boiler inside the waste heat recovery unit for medium-temperature convective cooling. The medium- and low-temperature sensible heat carried by the radiatively cooled crude syngas is transferred to the boiler feedwater or low-pressure steam medium, while the cooled crude syngas is generated.

9. The method for co-gasification of biomass and coal gasification fine slag according to claim 1, characterized in that, The cooled crude syngas is fed into the syngas purification unit for separation and dust removal, outputting clean syngas, including: The cooled crude syngas is fed into a porous filter element inside the syngas purification unit for dry dust removal and filtration. The porous filter element intercepts dry fly ash particles contained in the cooled crude syngas, thereby removing solid impurities and outputting clean syngas.

10. A biomass and coal gasification fine residue co-gasification system, implementing the biomass and coal gasification fine residue co-gasification method according to any one of claims 1-9, characterized in that, include: A biomass pretreatment unit receives biomass raw materials and performs crushing and drying treatment on the biomass raw materials, or performs crushing, drying and baking treatment to generate pretreated biomass raw materials. The fine slag pretreatment unit receives coal gasification fine slag, and the fine slag pretreatment unit performs drying, dehydration and pulverization treatment on the coal gasification fine slag to generate pretreated coal gasification fine slag; A mixing and grinding unit is connected to the biomass pretreatment unit and the fine residue pretreatment unit. The mixing and grinding unit receives the pretreated biomass raw material and the pretreated coal gasification fine residue. The mixing and grinding unit mixes and grinds the pretreated biomass raw material and the pretreated coal gasification fine residue to generate mixed powder. A gasifying agent supply unit is connected to the fluidized bed gasifier, and the gasifying agent supply unit supplies gasifying agent to the fluidized bed gasifier; A fluidized bed gasifier is connected to the mixed pulverizing unit. The fluidized bed gasifier receives the mixed powder and the gasifying agent. A synergistic gasification reaction occurs inside the fluidized bed gasifier. During this reaction, alkali metals and alkaline earth metals in the pretreated biomass feedstock come into contact with the residual carbon in the pretreated coal gasification fine slag and act as electron transfer mediators to promote the catalytic gasification reaction of the residual carbon. Gaseous alkali metal chlorides or free potassium and sodium ions released from the pretreated biomass feedstock undergo in-situ coordination and combination reactions with silica and alumina in the pretreated coal gasification fine slag, transforming them into chemical substances in the form of complex salt mineral crystal phases of leucite and mullite. These crystal phases adhere to the wall of the fluidized bed gasifier to form a slag layer, and liquid slag and crude syngas are generated. The slag removal unit is connected to the fluidized bed gasifier. The slag removal unit receives the liquid slag, quenches the liquid slag to generate solid coarse slag, and discharges it out of the system. The waste heat recovery unit of the waste boiler is connected to the fluidized bed gasifier. The waste heat recovery unit of the waste boiler receives the crude syngas and performs step cooling treatment on the crude syngas and recovers sensible heat to generate cooled crude syngas. The syngas purification unit is connected to the waste heat recovery unit of the waste boiler. The syngas purification unit receives the cooled crude syngas and performs separation and dust removal treatment on the cooled crude syngas to output clean syngas.

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