Gasification device, gasification system and biomass gasification method

Abstract

The invention provides a gasification device, a gasification system and a biomass gasification method, and belongs to the technical field of biomass gasification. The biomass gasification method comprises the following steps: carrying out pyrolysis gasification reaction on biomass and oxygen in a pyrolyzing furnace to obtain initial pyrolysis gas and coke; the method comprises the following steps: introducing coke into a first gasification furnace, and carrying out gasification reaction between the coke and oxygen and water vapor introduced into the first gasification furnace to obtain initial synthesis gas; introducing a part of the initial synthesis gas into a pyrolyzing furnace to provide heat for a pyrolysis gasification reaction; the temperature of the pyrolyzing furnace is higher than that of the first gasification furnace.

Description

Technical Field

[0001] The present application relates to the technical field of biomass gasification, and in particular, to a gasification device, a gasification system and a biomass gasification method. Background Art

[0002] Biomass is a promising renewable energy source. Promoting the resource utilization of abundant and environmentally friendly biomass materials will help promote energy conservation, environmental protection, and low-carbon development.

[0003] Biomass fuels primarily include crop straw, wood chips, sawdust, peanut shells, corn cobs, rice straw, wheat straw, wheat bran, tree branches and leaves, and licorice, which can replace traditional coal. As non-renewable energy resources such as underground oil, natural gas, and coal continue to decline, biomass fuels are increasingly widely used.

[0004] Currently, the main method used for biomass gasification is through fixed bed or fluidized bed gasification, etc., and the method of realizing the pyrolysis and gasification process of biomass through the above-mentioned fixed bed or fluidized bed gasification has the problems of low carbon conversion rate, high carbon dioxide content in the obtained synthesis gas, and high tar content in the synthesis gas. The subsequent separation cost is high, and it is difficult to directly carry out subsequent applications. Summary of the Invention

[0005] In view of this, in order to at least partially solve the above-mentioned technical problems, the present application provides a gasification device, a gasification system and a biomass gasification method.

[0006] According to an embodiment of one aspect of the present application, a biomass gasification method is provided, comprising: subjecting biomass to a pyrolysis and gasification reaction with oxygen in a pyrolysis furnace to obtain initial pyrolysis gas and coke; introducing the coke into a first gasification furnace to undergo a gasification reaction with oxygen and water vapor introduced into the first gasification furnace to obtain initial synthesis gas; introducing a portion of the initial synthesis gas into the pyrolysis furnace to provide heat for the pyrolysis and gasification reaction; the temperature of the pyrolysis furnace is higher than the temperature of the first gasification furnace.

[0007] According to an embodiment of another aspect of the present application, a gasification device is provided, comprising: a pyrolysis furnace for subjecting introduced biomass to a pyrolysis and gasification reaction to obtain coke and initial pyrolysis gas, comprising: a shell; a raw material inlet for receiving biomass arranged at the upper part of the shell; a first product outlet for discharging coke arranged at the lower part of the shell; an oxygen inlet arranged on the side wall of the shell; and a gasification unit, comprising: a first gasification furnace for subjecting coke to a gasification reaction with a gasifying agent to obtain an initial synthesis gas, the first gasification furnace having a plurality of inlets located at the lower end and an outlet located at the upper end, at least one inlet of the first gasification furnace being connected to the first product outlet of the pyrolysis furnace, the outlet of the first gasification furnace being used to discharge the obtained initial synthesis gas, the gasifying agent comprising oxygen and water vapor; the pyrolysis furnace is further provided with an initial synthesis gas inlet at the upper part of its shell, the initial synthesis gas inlet being connected to the first gasification furnace, and being used to pass a portion of the initial synthesis gas into the pyrolysis furnace.

[0008] According to an embodiment of yet another aspect of the present application, a gasification system is provided, comprising the gasification device as described above.

[0009] According to the biomass gasification method provided in the above-mentioned embodiment of the present application, considering that the pyrolysis furnace requires more heat to drive the pyrolysis and gasification reaction and thus produces too much carbon dioxide, a portion of the high-temperature initial synthesis gas is directly used to provide heat for the pyrolysis reaction, thereby improving the heat utilization rate. The high-temperature initial synthesis gas can directly transfer heat to the biomass, resulting in less heat loss. It can also prevent the pyrolysis furnace from producing too much carbon dioxide and reduce the content of ineffective gas. The present application is based on the combination of a pyrolysis furnace and a first gasification furnace. By refluxing a portion of the initial synthesis gas from the first gasification furnace to the pyrolysis furnace with a higher temperature, the efficient pyrolysis and gasification of biomass is promoted and converted into coke. When the coke is transferred to the first gasification furnace for gasification, the amount of tar in the first gasification furnace is reduced, thereby reducing the amount of tar in the initial synthesis gas flowing out of the pyrolysis furnace as a whole, reducing the cost of subsequent tar removal, and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other objects, features and advantages of the present application will become more apparent through the following description of the embodiments of the present application with reference to the accompanying drawings, in which:

[0011] Figure 1 A flow chart showing a biomass gasification method according to an embodiment of the present application is shown;

[0012] Figure 2 A schematic structural diagram of a gasification device according to an embodiment of the present application is shown;

[0013] Figure 3 A schematic structural diagram of a gasification device according to another embodiment of the present application is shown;

[0014] Figure 4A structural schematic diagram of a gasification system according to an embodiment of the present application is shown.

[0015] In the drawings, the meanings of the reference numerals are as follows:

[0016] 1- Pyrolysis furnace;

[0017] 11- housing;

[0018] 12- oxygen inlet;

[0019] 13-partition;

[0020] 14-Raw material entrance;

[0021] 15-First product export;

[0022] 16-initial synthesis gas inlet;

[0023] 17- Secondary product export;

[0024] 2-Gasification unit;

[0025] 21-first gasifier;

[0026] 211-Entrance;

[0027] 212-Exit;

[0028] 22-cyclone separator;

[0029] 23- second gasifier;

[0030] 24-returner;

[0031] 25-buffer tank;

[0032] 26-unloading valve;

[0033] 3- Melting furnace;

[0034] 31-fly ash burner;

[0035] 32-gas inlet;

[0036] 33-gas outlet;

[0037] 4-feeder;

[0038] 5-heat exchange unit;

[0039] 51-heat exchanger;

[0040] 52-waste heat boiler;

[0041] 53-heater;

[0042] 6-Synthesis gas purification and separation unit;

[0043] 61-dust collector;

[0044] 62-syngas purifier;

[0045] 7-boost pump;

[0046] a-biomass;

[0047] b-ash;

[0048] c-molten slag;

[0049] d-oxygen;

[0050] e-water vapor;

[0051] f- mixture of fly ash and CO2;

[0052] g-condensed water;

[0053] h-softened water;

[0054] i-recycled synthesis gas;

[0055] i1 - the first part of the recycled synthesis gas;

[0056] i2 - the second part of the recycled synthesis gas;

[0057] i'-high temperature circulating synthesis gas;

[0058] j-fly ash;

[0059] k-CO2;

[0060] o-cleaned synthesis gas;

[0061] m-first branch;

[0062] n-second branch;

[0063] g11-a pipeline for conveying coke from the pyrolysis furnace to the first gasification furnace; g21-a pipeline for conveying the initial synthesis gas from the first gasification furnace to the cyclone separator; g31-a pipeline for conveying a portion of the initial synthesis gas from the cyclone separator to the pyrolysis furnace; g41-a pipeline for conveying another portion of the initial synthesis gas from the cyclone separator to the outside of the gasification device; g22-a pipeline for conveying biomass ash from the discharge valve to the second gasification furnace, or a pipeline for conveying biomass ash from the discharge valve to the return feeder; g32-a pipeline for conveying the initial synthesis gas and initial pyrolysis gas from the pyrolysis furnace to the melting furnace; g33-a pipeline for conveying the first synthesis gas from the melting furnace to the second gasification furnace, or a pipeline for conveying the first synthesis gas directly from the melting furnace to the outside of the gasification device; g34-a pipeline for conveying the second synthesis gas from the second gasification furnace to the outside of the gasification device; g42-a pipeline from the heat exchanger to the synthesis gas purification and separation unit The pipeline for conveying another part of the initial synthesis gas; g35-the pipeline for conveying the second synthesis gas from the waste heat boiler to the synthesis gas purification and separation unit; g51-the pipeline for merging the synthesis gases of g42 and g35 and conveying them to the dust collector; g52-the pipeline for conveying synthesis gas from the dust collector to the synthesis gas purifier; g53-the pipeline for outputting purified synthesis gas from the synthesis gas purifier; g61-the pipeline for diverting part of the circulating synthesis gas from the purified synthesis gas; g71-the pipeline for conveying softened water to the waste heat boiler; g72-the pipeline for collecting high-temperature and high-pressure steam from the waste heat boiler; g73-the pipeline for conveying part of the high-temperature and high-pressure steam diverted to the heater; g74-the pipeline for conveying condensed water from the heater; g62-the pipeline for the second part of the preheated circulating synthesis gas to flow into the second temperature section of the heat exchanger; g63-the pipeline for conveying high-temperature circulating synthesis gas from the heat exchanger. DETAILED DESCRIPTION

[0064] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present application. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present application.

[0065] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0066] When expressions such as “at least one of A, B, and C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, and C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.). When expressions such as “at least one of A, B, or C, etc.” are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, “a system having at least one of A, B, or C” should include but is not limited to systems having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.).

[0067] In the related art, the biomass synthesis gas process involves a two-stage gasification reaction, directly connecting a melting furnace downstream of a fluidized bed. Pyrolysis and gasification occur within the fluidized bed, but the operating temperature of the fluidized bed is limited (mostly below 800°C). Within this temperature range, when tar is cracked, aromatic components tend to form condensed ring structures after cracking. For example, above 700°C, the tar gradually loses substituents on the aromatic hydrocarbon rings, forming more stable impurities such as aromatic hydrocarbons containing phenolic hydroxyl groups or methyl groups and five-membered carbon rings. Some monocyclic aromatic hydrocarbons and five-membered carbon ring tar components gradually polymerize into more chemically stable polycyclic aromatic hydrocarbons, resulting in a higher tar content in the synthesis gas obtained through pyrolysis and gasification. More importantly, the pyrolysis and gasification process consumes a lot of heat, resulting in excessive carbon dioxide production, which limits the degree of biomass pyrolysis and reduces carbon conversion.

[0068] In the process of realizing the concept of this application, it was found that this application introduces a portion of the initial synthesis gas into the pyrolysis furnace, and adaptively adjusts the temperature of the pyrolysis furnace to be higher than the gasification furnace, and uses the heat of the initial synthesis gas to provide heat for the pyrolysis and gasification reaction, thereby improving the heat utilization efficiency, and making the biomass more efficiently pyrolyzed and gasified, thereby improving the carbon conversion rate.

[0069] Specifically, according to an embodiment of one aspect of the present application, a biomass gasification method is provided. Figure 1 A flow chart showing a biomass gasification method according to an embodiment of the present application is shown; Figure 2 FIG. 1 shows a schematic structural diagram of a gasification device according to an embodiment of the present application. Figure 1~Figure 2 As shown, the method includes operations S101 to S103.

[0070] In operation S101 , biomass and oxygen are subjected to pyrolysis and gasification reaction in a pyrolysis furnace 1 to obtain initial pyrolysis gas and coke.

[0071] It should be noted that the initial pyrolysis gas includes combustible gases such as hydrogen, carbon monoxide, and small hydrocarbons below C2 (such as methane, ethane, and ethylene), as well as water vapor, carbon dioxide, and volatile matter. During the pyrolysis and gasification process, biomass char particles are also produced. Their properties are intermediate between those of the biomass feedstock and fully carbonized coke. The main components of biomass char particles are coke and biomass ash. The biomass ash may include some carbon-containing compounds as well as SiO2, CaO, and KO. These SiO2, CaO, and KO in the biomass ash rarely participate in the pyrolysis and gasification reactions. It is understood that the coke here refers to biomass char, with a fixed carbon content of, for example, 50-70%. The coke surface is rich in functional groups, such as hydroxyl and carboxyl groups, and has high reactivity. Volatile matter can be understood to include monocyclic or condensed-ring aromatic hydrocarbons, such as phenol and naphthalene. The pyrolysis and gasification reaction process is shown in the following equation:

[0072] Biomass + O2 → CH4 + CO + H2 + CO2 + C6H6O + C + C 10 H8+C2H6+C2H4.

[0073] In operation S102 , the coke is introduced into the first gasifier 21 , and undergoes a gasification reaction with oxygen and water vapor introduced into the first gasifier 21 to generate an initial synthesis gas.

[0074] It should be noted that the initial synthesis gas contains carbon monoxide, hydrogen, water vapor, and carbon dioxide. The coke produced during the pyrolysis and gasification process enters the first gasifier 21 and undergoes a gasification reaction. The reaction process of the gasification reaction is shown in the following formula:

[0075] C+O2→CO+CO2; C+H2O→CO+H2.

[0076] In operation S103 , a portion of the initial synthesis gas is introduced into the pyrolysis furnace 1 to provide heat for the pyrolysis and gasification reaction.

[0077] It should be noted that the heat utilization efficiency of the synthesis gas is improved and the heat loss is small due to the heat supply from the high-temperature initial synthesis gas introduced through the circulation between the pyrolysis furnace 1 and the first gasification furnace 21. It can also avoid the pyrolysis furnace 1 from producing excessive carbon dioxide and reduce the content of invalid gas.

[0078] According to the embodiment of the present application, by adaptively setting the temperature of the pyrolysis furnace 1 to be higher than the temperature of the first gasification furnace 21, at a temperature higher than that of the first gasification furnace 21, most of the volatile matter in the biomass is basically precipitated in the pyrolysis furnace 1, and part of the tar components can be fully cracked, thereby avoiding the aromatic components in the volatile matter from being converted into more stable aromatic hydrocarbons or five-membered carbon ring components, reducing the tar content and reducing the difficulty of subsequent cracking of the tar, thereby improving the biomass pyrolysis and gasification efficiency, thereby improving the carbon conversion rate, and reducing the cost of equipment for subsequent tar removal.

[0079] It should be noted that the first gasifier 21 can be understood as a device that converts coke into synthesis gas under a relatively high temperature environment, that is, through thermochemical reactions, the coke reacts with water vapor and oxygen to be converted into initial synthesis gas containing a mixed gas such as carbon monoxide, hydrogen, and methane.

[0080] The first gasifier 21 can use a fixed bed gasifier, a fluidized bed gasifier, etc. as needed. In this application, a fluidized bed gasifier is preferred.

[0081] Take the fluidized bed gasifier as an example to explain. Figure 2 As shown, the bottom of the first gasifier 21 can be filled with inert bed material, such as quartz sand, ash particles, or alumina pellets, to form a bed layer as needed. High-velocity fluidizing gas can be introduced from the bottom of the first gasifier 21 to suspend and tumble the bed material and coke in the bed layer, promoting thorough mixing and contact between the coke, oxygen, and water vapor, improving heat and mass transfer, and preventing local overheating and slagging.

[0082] The pyrolysis furnace 1 can be understood as a device that pyrolyzes and gasifies biomass at a relatively high temperature (higher than the first gasification furnace 21). The pyrolysis furnace 1 can be a moving bed, a fluidized bed, or a combination of the two as needed.

[0083] It should be noted that the part here can be understood as at least part of the initial synthesis gas. Further preferably, the volume content of a part of the initial synthesis gas accounts for less than 50% of the volume content of the entire initial synthesis gas, for example, it can be 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, or any value between the above two point values. Such a setting is more conducive to improving the heat utilization efficiency of the initial synthesis gas, avoiding the pyrolysis furnace from producing too much carbon dioxide, and reducing the content of invalid gas. More preferably, the volume content of a part of the initial synthesis gas is more than 10% and less than 30%, thereby ensuring that the heat utilization efficiency of the initial synthesis gas is high, avoiding excessive initial synthesis gas from diluting the oxygen concentration in the pyrolysis furnace 1 and the subsequent optional melting furnace 3, affecting the full cracking of tar. In some embodiments, the biomass gasification method also includes operation S104.

[0084] In operation S104, a portion of the initial synthesis gas and the initial pyrolysis gas introduced from the pyrolysis furnace 1 in step S103 are introduced into the melting furnace 3, and the tar in the initial synthesis gas and the initial pyrolysis gas is cracked to obtain a first synthesis gas.

[0085] In some embodiments, tar can be understood as the liquid or gaseous form of heavy organic matter that is not completely decomposed from the biomass during the biomass gasification process, that is, during the conversion to initial pyrolysis gas. Based on the aforementioned operations S101-S104, after the initial synthesis gas and initial pyrolysis gas from the pyrolysis furnace 1 are passed into the melting furnace 3, the tar content that needs to be processed is relatively low, which can shorten the reaction time in the melting furnace 3, thereby reducing the equipment volume and height of the melting furnace 3 and saving equipment costs.

[0086] The reaction process of the melting reaction is shown below:

[0087] C6H6O→3H2+5C+CO;C 10 H8→4H2+10C; 3C+2O2→2CO+CO2.

[0088] The melting furnace 3 can be understood as a high-temperature melting device for processing the tar produced after biomass gasification and synthesis. Usually, the temperature of the melting furnace 3 is higher than that of the pyrolysis furnace and the first gasification furnace. The tar in the initial synthesis gas and the initial pyrolysis gas is removed more thoroughly by high-temperature melting. The melting furnace 3 used in this application can be, for example, a cyclone melting furnace. Figure 2 As shown, the cyclone melting furnace can be understood as a combination of a cyclone separator and a melting furnace, achieving both ash separation and high-temperature melting. The initial synthesis gas and initial pyrolysis gas can enter the furnace body tangentially through the gas inlet 32 ​​on the side wall of the melting furnace 3, and oxygen d also enters the melting furnace 3 tangentially through another inlet on the side wall. Under the action of centrifugal force, the ash particles collide with the furnace wall. When close to the furnace wall, most of them are in a molten state at high temperature. Liquid slag is attached to the furnace wall. The liquid slag finally flows slowly along the wall and falls into the molten pool at the bottom. Finally, the molten slag c flows out of the slag outlet at the bottom of the melting furnace 3. The first synthesis gas, which has been de-ashed, flows out of the melting furnace 3 through the gas outlet 33 on the side wall.

[0089] In some embodiments, the temperature in the pyrolysis furnace 1 needs to be set below the ash melting point T1 to prevent slagging in the pyrolysis furnace 1. It should be noted that to avoid slagging in the pyrolysis furnace 1, the temperature of the pyrolysis furnace 1 can be set between T1-60°C and T1-30°C. This setting maximizes the carbon conversion rate during the pyrolysis and gasification processes while avoiding slagging. It also facilitates reducing the tar content in the initial syngas and initial pyrolysis gas in the pyrolysis furnace 1.

[0090] It should be noted that the ash melting point can be understood as the temperature range at which biomass ash (e.g., a combination of minerals and carbon-containing compounds) transitions from a solid state to a liquid state at high temperatures after gasification of biomass solid fuel. Biomass ash can be understood, for example, as a combination of acidic oxides, alkaline oxides, and other components. Acidic oxides include SiO2 and Al2O3; alkaline oxides include K2O, Na2O, CaO, and MgO; and other components include Fe2O3, TiO2, and carbon-containing compounds.

[0091] The ash melting point T1 can be determined by, for example, measuring the deformation temperature, softening temperature, and flow temperature of the ash using the cone method. The deformation temperature is defined as the temperature at which the tip of the cone begins to round or bend. The softening temperature is defined as the temperature at which the cone becomes spherical or the tip of the cone touches the base. The flow temperature is defined as the temperature at which the cone completely melts into a liquid state and becomes flowable.

[0092] It should be noted that biomass has a high alkali metal content, and the ash melting point T1 of its biomass ash is usually lower than that of coal fuel. The conventional biomass ash melting point T1 is between 900 and 1200°C.

[0093] Optionally, the temperature of the pyrolysis furnace 1 may be, for example, T1-60° C., T1-50° C., T1-40° C., T1-30° C., etc., or a range consisting of any two of the above values.

[0094] Further optionally, the temperature of the pyrolysis furnace 1 is 840-1170° C. The temperature of the pyrolysis furnace 1 can be, for example, 840° C., 900° C., 950° C., 1000° C., 1050° C., 1100° C., 1150° C., or 1170° C., or a range consisting of any two of the above values.

[0095] In some embodiments, the temperature of the first gasifier 21 is 600~950℃. Such a setting can promote the full gasification of coke as much as possible while avoiding the formation of coking and slagging due to overheating. If the temperature of the first gasifier 21 is too high, coking and slagging will occur in the first gasifier 21. Especially when there is a lot of coking and slagging in the fluidized bed gasifier, it is difficult to form a suspended tumbling state through fluidized gas. If the temperature of the first gasifier 21 is too low, the gasification reaction will be insufficient, and it will be difficult to achieve a high carbon conversion rate. Such a setting within the above range not only ensures the full gasification of coke to generate initial synthesis gas, but also ensures the normal operation of the first gasifier 21.

[0096] It should be noted that, within the above-mentioned temperature range, if it is necessary to increase the temperature of the first gasifier 21, this can be achieved by the following methods: increasing the amount of oxygen d in the first gasifier 21 (the same below), reducing the amount of water vapor e, reducing the amount of high-temperature circulating synthesis gas i', increasing the volume content of the initial synthesis gas on the first branch m, and reducing the volume content of the initial synthesis gas on the second branch n.

[0097] Optionally, the temperature of the first gasifier 21 may be, for example, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C or 950°C, or a range consisting of any two of the above values.

[0098] Preferably, the temperature of the first gasifier 21 is 700-850° C. This configuration further ensures sufficient carbon conversion efficiency.

[0099] In some embodiments, the temperature of the melting furnace 3 is ≥ 1000° C. This configuration allows for relatively thorough removal of tar from the initial synthesis gas and initial pyrolysis gas. Maintaining a relatively high temperature allows for relatively rapid tar removal, further reducing the time the initial synthesis gas and initial pyrolysis gas remain in the melting furnace 3, thereby reducing the volume of the melting furnace 3.

[0100] It should be noted that, within the above-mentioned temperature range, if it is necessary to increase the temperature of the melting furnace 3, the following methods can be used: increase the temperature of the pyrolysis furnace 1, increase the flow rate of oxygen d introduced tangentially into the melting furnace 3 or the flow rate of oxygen d introduced by the fly ash burner 31, reduce the volume content of the initial synthesis gas on the first branch m, and increase the volume content of the initial synthesis gas on the second branch n.

[0101] Optionally, the temperature of the melting furnace 3 may be, for example, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C, 1400°C or 1450°C, or a range consisting of any two of the above values.

[0102] More preferably, the temperature of the melting furnace 3 is 1100-1400° C. This configuration further removes tar while reducing resource waste.

[0103] In some embodiments, the biomass is in the form of biomass briquettes. Biomass briquettes can be understood as the aforementioned biomass fuel compressed and formed using a pressing device, without the need for additional additives and binders. The particles after briquetting have a large specific gravity and a small volume, making them easy to store and transport. In related technologies, the gasification furnaces used for biomass gasification mostly use low-gas-velocity bubbling beds, and the corresponding biomass briquettes that have not been treated by the pyrolysis furnace 1 may not fluidize well in the fluidized bed due to their large particle size and high density, resulting in a low carbon conversion rate.

[0104] In this application, the biomass briquettes explode during the pyrolysis and gasification process in the pyrolysis furnace 1, significantly reducing their particle size. This results in smaller coke particles, which prevent poor fluidization when entering the first gasifier 21. Biomass briquettes are less expensive than biomass powder, which has a lower density and is prone to flying, making packaging and transportation more difficult. Because biomass briquettes are used in this application, they can be broken into small biomass particles during the pyrolysis and gasification process, reducing storage and transportation costs.

[0105] In some embodiments, the pyrolysis furnace 1 is a moving bed or a fluidized bed; in this application, a moving bed is preferred.

[0106] This application uses the moving bed as an example to explain pyrolysis gasification. Figure 2 As shown, the moving bed can use a combination of co-current and counter-current methods. Biomass is added from the top of the moving bed and moves downward based on the process of drying, pyrolysis, gasification, and ash. Oxygen can be Figure 2 As shown, the oxygen is input from the side wall, and the oxygen introduced from the upper side wall contacts the biomass in the downstream direction, while the oxygen introduced from the lower side wall contacts the biomass in the countercurrent direction, thereby promoting sufficient contact and improving heat utilization.

[0107] In some embodiments, oxygen is introduced at different heights within the pyrolysis furnace 1 (e.g., a moving bed) to ensure a uniform and stable temperature within the moving bed. This allows for a sufficient pyrolysis and gasification reaction between the initial syngas, oxygen, and biomass briquettes, thereby improving the biomass carbon conversion efficiency. This uniform oxygen supply allows the volatile matter in the biomass briquettes to be substantially completely precipitated within the pyrolysis furnace 1, and allows for more tar in the initial syngas and initial pyrolysis gas to be cracked within the pyrolysis furnace 1. This further shortens the melting reaction time required within the melting furnace 3 and reduces the equipment volume of the melting furnace 3.

[0108] In some embodiments, the biomass gasification method further includes, before step S103, passing the initial syngas through a cyclone separator 22 to remove biomass ash. As previously described, biomass ash comprises oxides of mineral elements and carbon-containing compounds. Removing biomass ash through the cyclone separator 22 helps protect downstream equipment and reduces wear. Furthermore, the cyclone separator 22 provides preliminary dust removal, removing most larger particulate matter, alleviating the load on subsequent purification equipment and improving the quality of the initial syngas.

[0109] The cyclone separator 22 utilizes centrifugal force to separate solid particles from gas. It comprises a vertical cylindrical body with an inverted conical bottom. The initial syngas enters the cyclone separator 22 tangentially. Centrifugal force accelerates the separation of solid particles from the initial syngas, initially removing most of the larger biomass ash particles.

[0110] In some embodiments, after the aforementioned biomass ash removal operation, the process further includes passing the biomass ash into a second gasifier 23 to react with the first syngas from the melting furnace 3 to produce a second syngas. To maximize tar removal in the melting furnace 3, the temperature of the melting furnace 3 is typically set at a relatively high temperature. To achieve this high temperature, more effective gas from the initial syngas and initial pyrolysis gas is burned to provide heat. This causes some carbon monoxide in the initial syngas to react with oxygen in the melting furnace 3 and be converted into carbon dioxide, resulting in a lower effective gas (CO) content in the first syngas. The intense heat exchange between carbon-containing compounds in the biomass ash (e.g., partially unreacted coke) and carbon dioxide in the higher sensible heat of the first syngas, coupled with a redox reaction, converts a higher proportion of CO2 in the first syngas into combustible CO. This results in a higher CO content in the second syngas than in the first syngas, thereby increasing the proportion of effective gas in the syngas and improving the efficiency of the cold gas.

[0111] The second gasifier 23 can be one or more of a fixed bed, a fluidized bed, a moving bed, an entrained bed, and the like. The structure of the second gasifier 23 can be the same as or different from that of the first gasifier 21. Preferably, the second gasifier 23 is a moving bed, which can extend the residence time of the biomass ash in the second gasifier 23, ensure that the CO2 in the first syngas is fully reduced, increase the proportion of effective gas (CO) in the second syngas, and improve subsequent utilization efficiency.

[0112] In some embodiments, the temperature of the second gasifier 23 is 600-950°C. Similar to the first gasifier 21, such a setting can ensure that the coke and carbon dioxide fully react while avoiding coking and slagging, and further increase the proportion of effective gas in the second synthesis gas.

[0113] It should be noted that, within the above-mentioned temperature range, if it is necessary to increase the temperature of the second gasifier 23, the following methods can be used: reduce the total amount of gasifying agent (oxygen d + water vapor e + high-temperature circulating synthesis gas i') in the first gasifier 21, increase the volume content of the initial synthesis gas on the first branch m, reduce the volume content of the initial synthesis gas on the second branch n, and increase the temperature of the melting furnace 3.

[0114] Optionally, the temperature of the second gasifier 23 may be, for example, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C or 950°C, or a range consisting of any two of the above values.

[0115] Preferably, the temperature of the second gasifier 23 is 700-850° C. This arrangement further ensures sufficient effective gas conversion efficiency.

[0116] In some embodiments, the biomass gasification method further includes: passing at least one gas selected from another portion of the initial syngas, the first syngas, or the second syngas into the heat exchange unit 5 to preheat the circulating syngas i, and passing the preheated high-temperature circulating syngas i' into the first gasifier 21. Given that the first gasifier 21 utilizes a fluidized bed, the heat of the high-temperature circulating syngas i' after heat exchange in the heat exchange unit 5 is utilized to provide heat for the gasification reaction. Furthermore, the high-temperature circulating syngas i' is used as a fluidizing gas to promote thorough mixing and contact between the coke, oxygen, and water vapor, further enhancing heat and mass transfer.

[0117] It can be understood that the other part of the initial synthesis gas here accounts for more than 50% of the volume content of the entire initial synthesis gas, that is, the volume content of the initial synthesis gas introduced into the pyrolysis furnace 1 is less than or equal to the volume content of the initial synthesis gas directly flowing out of the gasification unit 2.

[0118] The heat exchange unit 5 can be understood as a heat exchange unit, which uses the heat in the generated synthesis gas to preheat the circulating synthesis gas i, thereby realizing heat recovery of the synthesis gas and improving heat utilization efficiency.

[0119] The circulating syngas i can be understood as the purified syngas o obtained by combining a portion of the initial syngas that has passed through the pyrolysis furnace 1 and another portion of the initial syngas that has been separated by the cyclone separator 22, followed by purification and separation. In the related art, the syngas that has passed through the melting furnace 3 is often used to gasify water, resulting in low cold gas efficiency. In this application, the circulating syngas i is converted into high-temperature circulating syngas i' using the heat exchange unit 5. This is then introduced into the first gasifier 21 as fluidizing gas, promoting sufficient gas-solid contact and providing improved heat and mass transfer.

[0120] In some embodiments, the circulating syngas i includes a first portion of circulating syngas i1 and a second portion of circulating syngas i2. Passing another portion of the initial syngas, the first syngas, and / or the second syngas through the heat exchange unit 5 to preheat the circulating syngas i includes using a heat exchanger 51 to preheat the first portion of the circulating syngas i1 with the other portion of the initial syngas, and using a waste heat boiler 52 to preheat the second portion of the circulating syngas i2 with the first syngas or the second syngas. This arrangement fully utilizes the sensible heat of the generated syngas, achieves heat transfer, improves heat and mass transfer, and increases the heat utilization efficiency of the generated syngas.

[0121] According to another embodiment of the present application, a gasification device is provided, such as Figure 2 As shown, the gasification device includes: a pyrolysis furnace 1 and a gasification unit 2.

[0122] The pyrolysis furnace 1 is used to carry out pyrolysis and gasification reaction of the biomass introduced therein. As described above, the biomass introduced into the pyrolysis furnace 1 reacts with oxygen to obtain coke and initial pyrolysis gas. The specific reaction process and the type of the pyrolysis furnace 1 are the same as described above and will not be repeated here.

[0123] Furthermore, the pyrolysis furnace 1 comprises a shell 11, an oxygen inlet 12, a feedstock inlet 14, and a first product outlet 15. The upper portion of the shell 11 is provided with a feedstock inlet 14 for receiving biomass a (further referred to as biomass briquettes). This arrangement utilizes the rising hot air flow generated by pyrolysis in the lower layer of the shell 11 for drying and preheating, promoting the breakup of the biomass briquettes into smaller particles. Furthermore, as the biomass a moves from top to bottom, continuous pyrolysis occurs, achieving progressive thermal conversion. The lower portion of the shell 11 is provided with a first product outlet 15 for discharging coke, facilitating rapid coke discharge and preventing excessive gasification. The sidewalls of the shell 11 are provided with oxygen inlets 12. This arrangement, with multiple gas inlets arranged horizontally, avoids the uneven gas-solid mixing that can result from bottom or top inlet placement, leading to uneven pyrolysis reactions. Furthermore, the cross-flow of oxygen d into the descending biomass a enhances the efficiency of the gas-solid reaction. The pyrolysis furnace 1 is further provided with an initial synthesis gas inlet 16 at the upper portion of its shell 11 . The initial synthesis gas inlet 16 is different from the raw material inlet 14 . The initial synthesis gas inlet 16 is used to receive the initial synthesis gas from the first gasification furnace 21 .

[0124] The gasification unit 2 includes a first gasification furnace 21. The type and structure of the first gasification furnace 21 are the same as described above.

[0125] Furthermore, the first gasifier 21 has a plurality of inlets at the lower end and an outlet 212 at the upper end. Figure 2 and Figure 3 In addition to the inlet 211 shown, the first gasifier also includes a gasifying agent inlet. An inlet 211 of the first gasifier is connected to the first product outlet 15 of the pyrolysis furnace 1 and is used to receive coke from the pyrolysis furnace 1. The outlet 212 of the first gasifier 21 is used to discharge the initial synthesis gas produced by the gasification reaction between the coke and the gasifying agent introduced into the first gasifier 21. The gasifying agent includes oxygen d and water vapor e. The gasifying agent can be introduced through the gasifying agent inlet located at the bottom of the first gasifier 21. The gasifying agent inlets for oxygen d and water vapor e can be different. The reactions occurring within the first gasifier 21 are the same as described above. The gasifying agent (oxygen and water vapor) introduced from the bottom, driven by the fluidizing gas, comes into countercurrent contact with the falling coke, extending the reaction time and improving the carbon conversion rate.

[0126] The pyrolysis furnace 1 has an initial syngas inlet 16 at the upper portion of the shell 11 thereof, which is different from the raw material inlet 14. The initial syngas inlet 16 is in communication with the first gasifier 21 and is configured to receive a portion of the initial syngas from the first gasifier 21.

[0127] According to an embodiment of the present application, the outlet 212 of the first gasifier 21 is connected to the initial synthesis gas inlet 16 of the pyrolysis furnace 1. By constructing a circulation connection between the pyrolysis furnace 1 and the gasification unit 2, it helps to improve the heat utilization efficiency of the synthesis gas; it also prevents the pyrolysis furnace from producing excessive carbon dioxide and reduces the content of invalid gas.

[0128] It should be noted that the bottom of the first gasifier 21 is a gas chamber for receiving oxygen d, water vapor e and high-temperature circulating synthesis gas i' for promoting fluidized contact from different gasifying agent inlets.

[0129] The pyrolysis furnace 1 further includes a second product outlet 17 , through which the obtained initial synthesis gas and initial pyrolysis gas are discharged from the pyrolysis furnace 1 .

[0130] The following combination Figure 2 The circulation flow process of biomass is explained.

[0131] Biomass a is introduced into the pyrolysis furnace 1 through the feedstock inlet 14 located at the top of the housing 11. Oxygen d is introduced into the pyrolysis furnace 1 through the oxygen inlet 12 located on the sidewall of the housing 11. The biomass a and oxygen d undergo a pyrolysis and gasification reaction in the pyrolysis furnace 1, producing initial pyrolysis gas and coke. The coke exits the pyrolysis furnace 1 through the first product outlet 15 located at the bottom of the housing 11 and is fed into the first gasification furnace 21 through the lower inlet 211 via pipe g11. The coke reacts with oxygen d and water vapor e introduced into the bottom chamber of the first gasification furnace 21 to produce initial syngas. The initial syngas exits the first gasification furnace 21 through outlet 212, initially flowing through pipe g21. A portion of the initial syngas is then diverted and flows through pipe g31 into the pyrolysis furnace 1 through the initial syngas inlet 16.

[0132] In some embodiments, the gasification device further includes a feeder 4, located downstream of the product outlet 15 at the bottom of the pyrolysis furnace 1, adapted to propel the coke in the pipeline g11 toward the first gasification furnace 21. Since the temperature of the pyrolysis furnace 1 is higher than that of the first gasification furnace 21, the coke needs to be cooled during transportation. Therefore, the type of feeder 4 used may be, for example, a screw feeder, the outer surface of which may have a cooling tube, the cooling tube containing a cooling medium for removing the high temperature of the coke itself through a circulating cooling medium. The cooling medium may be, for example, cooling water or cooling oil, which is not specifically limited in this application.

[0133] It can be understood that during the process of conveying coke, the spiral blades of the screw feeder are in rotation, which stirs and loosens the coke to prevent the coke from agglomerating and piling up.

[0134] In some embodiments, the gasification unit further includes a melting furnace 3. The type of the melting furnace 3 and the reactions therein are the same as described above and will not be described in detail here.

[0135] Furthermore, a melting furnace 3 is located downstream of the pyrolysis furnace 1. The melting furnace 3 is used to crack the tar in the initial synthesis gas and the initial pyrolysis gas to produce a first synthesis gas. The melting furnace 3 has a gas inlet 32 ​​for receiving the initial synthesis gas and the initial pyrolysis gas from the pyrolysis furnace 1 and a gas outlet 33 for discharging the first synthesis gas. The gas inlet 32 ​​of the melting furnace 3 is connected to the second product outlet 17 of the pyrolysis furnace 1.

[0136] The melting furnace 3 also has a fly ash burner 31. The mixture f of fly ash and CO2 injected from the fly ash burner 31 is heated and melted under the action of oxygen e.

[0137] The following Figure 2 As an example, the material flow process in the melting furnace 3 (eg, a cyclone melting furnace) is discussed in detail.

[0138] The initial synthesis gas and initial pyrolysis gas from the pyrolysis furnace 1 enter the melting furnace 3 tangentially through the gas inlet 32 ​​of the melting furnace 3 from the second product outlet 17 on the upper part of the side wall of the melting furnace 3 via the pipe g32, and the oxygen d enters the melting furnace 3 tangentially through another pipe. The mixture f of fly ash and CO2 finally collected by the gasification device and the oxygen d are sprayed into the melting furnace 3 from the fly ash burner 31 located at the top of the melting furnace 3, so that the initial synthesis gas and initial pyrolysis gas, oxygen d, fly ash and CO2 mixture f rotate strongly in the melting furnace 3, and a high-temperature gasification and melting reaction occurs, and the part of the biomass ash that cannot participate in the reaction is drawn out from the bottom of the melting furnace 3 in the form of molten slag c. The first synthesis gas obtained after removing the tar is drawn out of the melting furnace 3 from the gas outlet 33 through the pipe g33 and flows into the subsequent links.

[0139] In some embodiments, the gasification unit 2 further includes a cyclone separator 22 in communication with the outlet 212 of the first gasifier 21. The cyclone separator 22 is used to separate and remove biomass ash mixed in the initial syngas (as mentioned above, the biomass ash contains coke or carbonaceous compounds, etc.).

[0140] Furthermore, a first branch m and a second branch n are provided downstream of the cyclone separator 22. The first branch m is used to convey a portion of the initial syngas from the cyclone separator 22 to the pyrolysis furnace 1; the second branch n conveys another portion of the initial syngas from the cyclone separator 22 out of the gasification unit 2. Compared to the related art practice of generally directing all of the prepared syngas into the melting furnace, this arrangement, when using the same melting furnace and the same amount of oxygen, diverting a portion of the initial syngas into the melting furnace 3, can reduce the amount of initial syngas entering the melting furnace 3. This helps increase the relative oxygen concentration, promotes the forward progress of tar cracking, and thereby reduces the CO2 content in the melting furnace 3, increases the proportion of effective gas in the syngas, and further improves the carbon conversion rate.

[0141] The following Figure 2 As an example, the flow direction of the initial synthesis gas in the cyclone separator 22 is discussed in detail.

[0142] The initial synthesis gas from the first gasifier 21 flows into the cyclone separator 22 through the outlet 212 along the pipe g21. As mentioned above, the cyclone separator 22 uses the centrifugal force to separate the initial synthesis gas into two parts. One part of the initial synthesis gas flows along the first branch m (also known as Figure 2 The pipeline g31 in the figure is transported to the pyrolysis furnace 1, and the other part of the initial synthesis gas is transported along the second branch n (which can also be understood as Figure 2 The biomass ash is transported out of the gasification unit 2 via the pipeline g41 in the gasification unit 2 for subsequent separation and purification steps. The separated biomass ash flows out of the cyclone separator 22 via the bottom outlet of the cyclone separator 22 along the pipeline g22.

[0143] In some embodiments, a buffer tank 25 and a discharge valve 26 are sequentially provided downstream of the bottom outlet of the cyclone separator 22. The buffer tank 25 is used to regulate the flow of biomass ash. Since the biomass ash flowing out of the cyclone separator 22 has a relatively high flow rate, the buffering effect of the buffer tank 25 helps to alleviate the rate difference between the upstream discharge and downstream processing equipment, thereby avoiding blockage of the pipeline g22 or the subsequent reaction device. The discharge valve 26 is a device for regulating the opening and closing of the biomass ash to further flow to the next link. By adjusting the opening and closing frequency of the discharge valve 26, the inflow and rate of the biomass ash to the subsequent link can be accurately controlled to maintain a stable and appropriate residence time of the biomass ash.

[0144] In some embodiments, the gasification device includes a melting furnace 3, and the gasification unit 2 includes a second gasifier 23. The second gasifier 23 is used to react biomass ash with the first syngas to produce a second syngas. The second gasifier 23 has an inlet for receiving biomass ash from the cyclone separator 22 and another inlet for receiving the first syngas from the melting furnace 3. The second gasifier 23 is used to reduce the CO2 content in the produced syngas, increase the proportion of effective gas in the syngas, and improve the efficiency of the cold gas.

[0145] The following Figure 2 Taking as an example, the material flow process in the second gasifier 23 is discussed in detail.

[0146] Biomass ash from the cyclone separator 22 flows along pipe g22 and into the second gasifier 23 through an inlet at the top. The first syngas from the melting furnace 3 enters the second gasifier 23 tangentially through another inlet on the sidewall of the second gasifier 23. The coke in the biomass ash undergoes an oxidation-reduction reaction with the carbon dioxide in the first syngas, producing carbon monoxide, which in turn increases the effective gas content in the generated second syngas. After a thorough reaction under centrifugal force, the second syngas and recycled ash (biomass ash after the coke has been removed) are produced. The second syngas flows out of the gasification unit 2 through pipe g34 and enters the subsequent process. The resulting recycled ash flows out of the bottom of the second gasifier 23 and flows back into the bottom of the first gasifier 21, serving as bed material. During the reaction, the recycled ash is heated by the higher-temperature first syngas, causing it to flow back into the first gasifier 21, providing heat for the gasification reaction. This transfers the high-temperature heat of the first syngas to the gasification reaction, improving the gasification cold gas efficiency of the reaction.

[0147] Optionally, the second gasifier 23 may be a moving bed, thereby extending the residence time of the biomass ash, ensuring that the carbon dioxide in the first synthesis gas is fully reduced, and further increasing the effective gas ratio.

[0148] It should be noted that, based on the cyclone separator 22, the initial synthesis gas is divided into two parts, and the tar is cracked by using a melting reaction, and the carbon dioxide in the obtained first synthesis gas is reacted with the coke in the biomass ash, so that the obtained synthesis gas is compared with the gas composition in the related technology. The method of the present application increases the volume content of effective gas (H2, CO) in the synthesis gas by more than 5%.

[0149] In some embodiments, the gasification unit further includes a returner 24, which is located downstream of the circulating ash outlet at the bottom of the second gasification furnace 23. The returner 24 is used to return the circulating ash separated from the second gasification furnace 23 to the first gasification furnace 21, forming a circulating flow of materials and providing heat for the gasification reaction process to ensure stable operation of the gasification reaction.

[0150] In some embodiments, during the introduction of the first syngas into the second gasifier 23, recycled syngas i, cooled to below the ash melting point, may also be introduced. The recycled syngas i enters the upper portion of the second gasifier 23 tangentially, carrying biomass ash with it in a high-speed rotation to promote sufficient heat exchange between the biomass ash and the first syngas. The addition of the recycled syngas i cools the first syngas to below the ash melting point, preventing it from adhering to the heating surfaces of subsequent equipment and ensuring its fluidity.

[0151] Furthermore, the gasification device can be provided with a second gasification furnace 23 as required, or Figure 3 As shown, the second gasifier 23 is not provided.

[0152] by Figure 3 For example, the material flow process of the material without the second gasification furnace 23 is described in detail.

[0153] The aforementioned reaction process is identical to that in the case of a second gasifier 23 and will not be further described. The difference is that the initial syngas produced by the first gasifier 21 enters the cyclone separator 22 via pipeline g21. The biomass ash flowing out of the bottom of the cyclone separator 22 flows through the buffer tank 25 and the discharge valve 26, then directly into the return feeder 24 along pipeline g22. The return feeder 24 then returns the biomass ash to the first gasifier 21. Furthermore, the first syngas flowing out of the melting furnace 3 flows directly out of the gasification device via pipeline g33.

[0154] It should be noted that when the second gasifier 23 is not provided, it is still necessary to introduce circulating synthesis gas i into the pipeline g33. The addition of circulating synthesis gas i can cool the first synthesis gas to below the ash melting point, avoid the adhesion of the first synthesis gas to the heating surface of subsequent equipment, and ensure the fluidity of the first synthesis gas.

[0155] In some embodiments, the pyrolysis furnace 1 is provided with multiple oxygen inlets 12 at different heights of the side wall of the shell 11. The provision of multiple oxygen inlets 12 allows for more uniform oxygen d to be introduced at different heights, thereby avoiding local overheating or incomplete combustion, promoting stable pyrolysis and gasification reactions, and allowing for sufficient release of volatile matter from the biomass.

[0156] It should be noted that multiple oxygen inlets 12 are provided at different heights of the side wall. This can be based on the different demands for oxygen d at different heights. For example, a small amount of oxygen d can be introduced into the upper area of ​​the pyrolysis furnace 1 to maintain the pyrolysis environment and avoid excessive oxidation; the amount of oxygen d introduced into the lower area of ​​the pyrolysis furnace 1 can be appropriately increased to promote the combustion and gasification of biomass semi-coke, etc., and provide heat to maintain the continuous progress of the reaction.

[0157] In some embodiments, at least one partition 13 is provided within the housing 11. The partition 13 extends along the height of the pyrolysis furnace 1 and is not connected to the bottom of the pyrolysis furnace 1. The partition 13 divides the interior of the pyrolysis furnace 1 into at least two longitudinal zones, thereby extending the residence time of the biomass a within the pyrolysis furnace 1 and preventing incomplete reaction due to rapid descent. A gap is maintained at the bottom of the pyrolysis furnace 1 to allow airflow to bypass the partition 13 from below, thereby increasing the contact area and / or duration between the gas phase and the solid phase and preventing heat accumulation.

[0158] According to another embodiment of the present application, a gasification system is provided. Figure 4 A schematic diagram of the structure of a gasification system according to an embodiment of the present application is shown in FIG. Figure 4 As shown, the gasification system includes the above-mentioned gasification device.

[0159] According to the embodiments of the present application, as described above, the initial synthesis gas prepared in the first gasifier 21 is refluxed into the pyrolysis furnace 1 at a higher temperature, thereby ensuring an efficient pyrolysis and gasification process of the biomass and helping to improve the carbon conversion rate; at the same time, the tar content in the first gasifier 21 and the pyrolysis furnace 1 is reduced, thereby reducing the cost of subsequent tar removal.

[0160] It can be understood that the gasification system of the present application includes the aforementioned gasification device, and the same parts will not be repeated.

[0161] In some embodiments, the gasification system further comprises a heat exchange unit 5. The heat exchange unit 5 comprises a heat exchanger 51, which is used to preheat the circulating synthesis gas i using the heat of another portion of the initial synthesis gas (the initial synthesis gas flowing through the second branch n). The shell of the heat exchanger 51 is provided with the following Figure 4 The tube bundles or plates shown form independent flow paths for different fluids. Heat exchanger 51 recovers waste heat from the initial syngas to preheat the circulating syngas i, achieving efficient energy utilization. The heated, high-temperature circulating syngas i' provides heat for the gasification reaction in the first gasifier 21 and acts as fluidizing gas, promoting sufficient contact between the coke and the gasifying agent.

[0162] It is understandable that the preheated circulating synthesis gas i can be full or partial, and can be specifically adjusted according to the amount of heat of the initial synthesis gas and the demand for fluidizing gas. This application does not impose any special restrictions on this.

[0163] In some embodiments, the gasification system includes the aforementioned gasification device. In some cases, the gasification device in the gasification system includes a melting furnace 3. This means that after passing through the gasification device, the syngas exiting the gasification device comprises a first syngas. In other cases, the gasification device in the gasification system also includes a second gasification furnace 23. This means that the syngas exiting the gasification device comprises a second syngas. The difference between the first syngas and the second syngas is as previously described and will not be further elaborated here.

[0164] In some embodiments, the presence of cyclone separator 22 allows for separate utilization of the heat of the initial syngas from different branches. Specifically, heat exchanger 51 is configured to utilize the heat of a portion of the initial syngas (the initial syngas passing through second branch n) to preheat the first portion of the circulating syngas i1 in the circulating syngas i.

[0165] In some embodiments, the heat exchange unit 5 further comprises: a waste heat boiler 52 for utilizing the heat of the initial synthesis gas (passing through the first branch m), that is, the heat of the first synthesis gas formed after the circulation (directly as Figure 3 As shown, the heat of the second synthesis gas (after the melting furnace 3 as shown in FIG33 flows out of the gasification device) or the heat of the second synthesis gas (after the melting furnace 3 as shown in FIG33 Figure 2 The second portion of the circulating syngas i2 is preheated by the second gasifier 23 and then flows out of the gasification device through the pipeline g34. This arrangement fully utilizes the sensible heat of the generated syngas, increasing the cold gas efficiency of the biomass gasification system.

[0166] It should be noted that before using the waste heat boiler 52 to preheat the second part of the circulating synthesis gas i2, it also includes using the waste heat boiler 52 to use the heat of the first synthesis gas or the heat of the second synthesis gas to preheat the introduced softened water h to obtain high-temperature water vapor e, and then the obtained water vapor e is introduced into the first gasification furnace 21 to further fully utilize the sensible heat of the synthesis gas.

[0167] In some embodiments, the heat exchanger 51 includes: a first temperature section and a second temperature section. The temperature of the first temperature section is lower than that of the second temperature section. It can be understood that the first temperature section is a low temperature section and the second temperature section is a high temperature section. Figure 4 As shown, the first temperature section is located on the right side of the heat exchanger 51, and the second temperature section is located on the left side of the heat exchanger 51. Of course, the positions of the two can also be interchanged, and this application does not make any special restrictions on this.

[0168] The circulating synthesis gas i can include a first part of the circulating synthesis gas i1 and a second part of the circulating synthesis gas i2 as needed. Figure 4As shown, the first temperature section is equipped with an inlet for the first portion of the circulating syngas i1 and an outlet for the initial syngas. The second temperature section is equipped with an inlet for the preheated second portion of the circulating syngas i2 and an outlet for the initial syngas. The first portion of the circulating syngas i1 and the preheated second portion of the circulating syngas i2 are mixed in the second temperature section. This arrangement ensures that the high-temperature circulating syngas i' flowing out of the heat exchanger 51 is within the design range suitable for the first gasifier 21 and fully utilizes the heat.

[0169] In some embodiments, the heat exchange unit 5 further includes a heater 53 located downstream of the waste heat boiler 52. The heater 53 is used to preheat the second partial circulating syngas i2 using the heat from excess steam e generated by the waste heat boiler 52, producing preheated second partial circulating syngas i2 and condensed water g. The preheated second partial circulating syngas i2 is then passed together with the first partial circulating syngas i1 into the second temperature zone of the heat exchanger 51. This arrangement further maximizes the sensible heat of the syngas and improves the cold gas efficiency of the gasification system.

[0170] In some embodiments, the gasification system further includes a syngas purification and separation unit 6, adapted to remove dust and purify the syngas flowing out of the heat exchange unit 5. The resulting syngas flows through a pipeline g51 into the syngas purification and separation unit 6, where it first flows into a dust collector 61 for dedusting to remove residual fly ash j. After the fly ash j is removed, the syngas enters a syngas purifier 62 for thorough purification, yielding purified syngas o. A portion of the purified syngas o, referred to as the circulating syngas i, is then transported via a booster pump 7 to the heat exchange unit 5. After preheating in the heat exchange unit 5, high-temperature circulating syngas i' is generated and introduced into the first gasifier 21. If a second gasifier 23 is required, the circulating syngas i is transported via a pipeline to the second gasifier 23 to cool the first syngas and prevent slagging within the second gasifier 23 due to excessive temperatures. When the second gasifier 23 is not needed, the circulating synthesis gas i is introduced into the pipeline g33 to cool the temperature of the first synthesis gas to below the ash melting point to avoid adhesion to subsequent devices.

[0171] The fly ash j treated by the dust collector 61 is combined with the introduced CO2 to form a mixture f of fly ash and CO2, which enters the melting furnace 3 through the fly ash burner 31 for a melting reaction, so that the carbon-containing compounds in the fly ash are completely reacted, and the fly ash is melted into molten slag c, which is discharged from the bottom of the melting furnace 3, thereby ensuring zero fly ash in the gasification system and greatly improving the carbon conversion rate and cold gas efficiency of the gasification system.

[0172] It should be noted that if Figure 4As shown, regulating valves are respectively provided on multiple pipelines of the present application, such as pipelines g42 and g35, to adjust the flow rate and flow velocity of the synthesis gas.

[0173] The material flow and gas flow of the gasification system of the present application will be described in detail below using specific embodiments, depending on whether the second gasifier 23 is provided.

[0174] In a specific embodiment, the gasification system of the present application includes a second gasifier 23 .

[0175] Material flow: Biomass a (for example, in the form of briquettes) → pyrolysis furnace 1 (biomass a turns into coke after reaction in pyrolysis furnace 1) → feeder 4 → pipeline g11 → first gasification furnace 21 → pipeline g21 → cyclone separator 22 → buffer tank 25 → discharge valve 26 → pipeline g22 → second gasification furnace 23 → return feeder 24 → first gasification furnace 21.

[0176] The entire synthesis gas production process is divided into: gas process 1 (gas process on the first branch m), gas process 2 (gas process on the second branch n), and the process after the confluence of gas process 1 + gas process 2.

[0177] Gas flow 1: First gasifier 21 (initial synthesis gas can be, for example, 700-850°C) → pipeline g21 → cyclone separator 22 → pipeline g31 (first branch m) → pyrolysis furnace 1 (operating temperature range is T1-60 to T1-30°C, T1 is the ash melting point, and the general biomass ash melting point range is 900-1200°C) → pipeline g32 → melting furnace 3 → pipeline g33 → second gasifier 23 → pipeline g34 → waste heat boiler 52 → pipeline g35 → merge into pipeline g51.

[0178] Gas flow 2: first gasifier 21 (initial synthesis gas can be, for example, 700-850°C) → pipeline g21 → cyclone separator 22 → pipeline g41 (second branch n) → heat exchanger 51 → pipeline g42 → merge into pipeline g51.

[0179] The process after the gas flow 1 + gas flow 2 are merged is: pipeline g51 → dust collector 61 → pipeline g52 → synthesis gas purifier 62 → pipeline g53 → separation of the purified synthesis gas o → pipeline g61 → separation of the circulating synthesis gas i through the booster pump 7 for heat exchange.

[0180] The circulation process of biomass ash is: first gasifier 21 → pipeline g21 → cyclone separator 22 → buffer tank 25 → discharge valve 26 → second gasifier 23 → return device 24 → first gasifier 21.

[0181] In a specific embodiment, the gasification system of the present application does not include the second gasifier 23 .

[0182] Material flow: Biomass a (for example, in the form of briquettes) → pyrolysis furnace 1 (biomass a becomes coke after reaction in pyrolysis furnace 1) → feeder 4 → pipeline g11 → first gasification furnace 21 → pipeline g21 → cyclone separator 22 → buffer tank 25 → discharge valve 26 → pipeline g22 → return feeder 24 → first gasification furnace 21.

[0183] The entire synthesis gas production process is divided into: gas process 1 (gas process on the first branch m), gas process 2 (gas process on the second branch n), and the process after the confluence of gas process 1 + gas process 2.

[0184] Gas flow 1: First gasifier 21 (initial synthesis gas can be, for example, 700-850°C) → pipeline g21 → cyclone separator 22 → pipeline g31 (first branch m) → pyrolysis furnace 1 (operating temperature range is T1-60 to T1-30°C, T1 is the ash melting point, and the general biomass ash melting point range is 900-1200°C) → pipeline g32 → melting furnace 3 → pipeline g33 → waste heat boiler 52 → pipeline g35 → merges into pipeline g51.

[0185] Gas flow 2: first gasifier 21 (initial synthesis gas can be, for example, 700-850°C) → pipeline g21 → cyclone separator 22 → pipeline g41 (second branch n) → heat exchanger 51 → pipeline g42 → merge into pipeline g51.

[0186] The process after the gas flow 1 + gas flow 2 are merged is: pipeline g51 → dust collector 61 → pipeline g52 → synthesis gas purifier 62 → pipeline g53 → separation of the purified synthesis gas o → pipeline g61 → separation of the circulating synthesis gas i through the booster pump 7 for heat exchange.

[0187] The circulation process of biomass ash is: first gasifier 21 → pipeline g21 → cyclone separator 22 → buffer tank 25 → discharge valve 26 → return device 24 → first gasifier 21.

[0188] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of this application. It should be understood that the above is only a specific embodiment of this application and is not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A biomass gasification method comprising: The biomass is subjected to pyrolysis and gasification reaction with oxygen in a pyrolysis furnace to obtain initial pyrolysis gas and coke; The coke is introduced into a first gasifier to undergo a gasification reaction with oxygen and water vapor introduced into the first gasifier to obtain an initial synthesis gas; Passing a portion of the initial synthesis gas into the pyrolysis furnace to provide heat for the pyrolysis and gasification reaction; Wherein, the temperature of the pyrolysis furnace is higher than the temperature of the first gasification furnace.

2. The biomass gasification method according to claim 1, wherein: The biomass gasification method further comprises: A portion of the initial synthesis gas and the initial pyrolysis gas from the pyrolysis furnace are introduced into a melting furnace, and the tar in the initial synthesis gas and the initial pyrolysis gas is cracked to obtain a first synthesis gas.

3. The biomass gasification method according to claim 2, wherein: The temperature of the first gasification furnace is 600-950°C, and the temperature of the melting furnace is ≥1000°C.

4. The biomass gasification method according to claim 2, wherein: Before introducing a portion of the initial synthesis gas into the pyrolysis furnace, the biomass gasification method further comprises: The initial syngas is passed through a cyclone separator to remove biomass ash.

5. The biomass gasification method according to claim 4, wherein: The biomass gasification method further comprises: Passing the biomass ash into a second gasification furnace to react with the first synthesis gas from the melting furnace to obtain a second synthesis gas; Preferably, the temperature of the second gasifier is 600-950°C.

6. The biomass gasification method according to any one of claims 1 to 5, wherein: The pyrolysis furnace is a moving bed or a fluidized bed.

7. The biomass gasification method according to any one of claims 1 to 5, wherein: The biomass gasification method further includes: introducing oxygen at different heights of the pyrolysis furnace during the pyrolysis and gasification reaction.

8. The biomass gasification method according to claim 1, 2 or 5, wherein: The biomass gasification method further comprises: At least one gas selected from another portion of the initial synthesis gas, the first synthesis gas, or the second synthesis gas is introduced into a heat exchange unit to preheat the circulating synthesis gas, and the preheated high-temperature circulating synthesis gas is introduced into the first gasifier.

9. The biomass gasification method according to claim 8, wherein: The circulating synthesis gas includes: a first portion of circulating synthesis gas and a second portion of circulating synthesis gas; The step of introducing at least one gas selected from another portion of the initial synthesis gas, the first synthesis gas, or the second synthesis gas into a heat exchange unit to preheat the circulating synthesis gas comprises: The other part of the initial synthesis gas is used to preheat the first part of the circulating synthesis gas by using a heat exchanger, and the first synthesis gas or the second synthesis gas is used to preheat the second part of the circulating synthesis gas by using a waste heat boiler.

10. A gasification device comprising: The pyrolysis furnace is used to carry out pyrolysis and gasification reaction of the introduced biomass to obtain coke and initial pyrolysis gas, including: case; a raw material inlet disposed at an upper portion of the housing for receiving the biomass; a first product outlet provided at a lower portion of the shell for discharging the coke; and, an oxygen inlet provided on a side wall of the housing; Gasification unit, including: a first gasifier, configured to gasify the coke and a gasifying agent to produce an initial synthesis gas, the first gasifier comprising a plurality of inlets at a lower end and an outlet at an upper end, at least one of the inlets of the first gasifier being connected to a first product outlet of the pyrolysis furnace, the outlet of the first gasifier being configured to discharge the obtained initial synthesis gas, the gasifying agent comprising oxygen and water vapor; The pyrolysis furnace is further provided with an initial synthesis gas inlet at the upper portion of its shell. The initial synthesis gas inlet is communicated with the first gasification furnace and is used to pass a portion of the initial synthesis gas into the pyrolysis furnace.

11. The gasification device according to claim 10, wherein: The gasification unit further comprises: The melting furnace is located downstream of the pyrolysis furnace and is used to crack the tar in the initial synthesis gas and the initial pyrolysis gas to obtain a first synthesis gas; the melting furnace has a gas inlet for receiving the portion of the initial synthesis gas and the initial pyrolysis gas from the pyrolysis furnace and a gas outlet for discharging the first synthesis gas.

12. The gasification device according to claim 10 or 11, wherein: The gasification unit further comprises: a cyclone separator, connected to the outlet of the first gasifier, the cyclone separator being used to separate and remove biomass ash from the initial synthesis gas; A first branch and a second branch are provided downstream of the cyclone separator. The first branch is used to transport a portion of the initial synthesis gas from the cyclone separator to the pyrolysis furnace, and the second branch is used to transport another portion of the initial synthesis gas from the cyclone separator out of the gasification unit.

13. The gasification device according to claim 12, wherein: The gasification unit includes the melting furnace and further includes: The second gasifier is used to react the biomass ash with the first synthesis gas to obtain a second synthesis gas; the second gasifier has an inlet for receiving the biomass ash from the cyclone separator and another inlet for receiving the first synthesis gas from the melting furnace.

14. The gasification device according to claim 10 or 11, wherein: The pyrolysis furnace is provided with a plurality of oxygen inlets at different height positions of the side wall of the shell; and / or, At least one partition is provided in the shell. The partition extends from the top of the pyrolysis furnace along the height direction of the pyrolysis furnace to the bottom of the pyrolysis furnace and is not connected to the bottom of the pyrolysis furnace.

15. A gasification system comprising the gasification device according to any one of claims 10 to 14.

16. The gasification system according to claim 15, wherein: The gasification system further comprises: The heat exchange unit comprises a heat exchanger, which is used to preheat all or part of the circulating synthesis gas by utilizing the heat of another part of the initial synthesis gas.

17. The gasification system according to claim 16, wherein: The gasification system comprises the gasification device according to claim 10 or 12, The heat exchanger is used to preheat the first part of the circulating synthesis gas by utilizing the heat of the other part of the initial synthesis gas; The heat exchange unit further includes: The waste heat boiler is used to preheat the second portion of circulating synthesis gas using the heat of the first synthesis gas or the heat of the second synthesis gas to obtain the preheated second portion of circulating synthesis gas.

18. The gasification system according to claim 17, wherein: The heat exchanger comprises: a first temperature section and a second temperature section, wherein the temperature of the first temperature section is lower than the temperature of the second temperature section; The first temperature section is provided with an inlet for the first part of the circulating synthesis gas and an outlet for the initial synthesis gas, and the second temperature section is provided with an inlet for the preheated second part of the circulating synthesis gas and an inlet for the initial synthesis gas, so that the first part of the circulating synthesis gas and the preheated second part of the circulating synthesis gas are mixed in the second temperature section.

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