A biomass pellet combustion device with bottom air intake and an ignition method

Abstract

This invention discloses a bottom-inlet biomass pellet combustion device and its ignition method, relating to the field of biomass gasification technology. The device adopts a double-shell, two-stage bottom-suction gasifier structure, mainly including an outer shell, inner furnace components, an oxidation throat, a reducer, a gas supply pipe, and a central igniter. Fan blades are installed on the outer side of the inner furnace components, driven by the produced combustible gas to achieve automatic stirring and uniform heating of the material. A low-temperature gasifying agent is introduced into the gas supply pipe, causing the alkali metals released from the biomass to condense directionally on the pipe wall, reducing corrosion of core components. The oxidation throat forms a high-temperature zone for deep tar cracking. During ignition, the material is first dried by the central igniter, then undergoes cracking, high-temperature oxidation, and reduction reactions to generate high-calorific-value combustible gas. Combined with bottom air intake and spark plug temperature control, a stable reaction temperature is maintained inside the furnace. This invention has advantages such as low tar content, minimal alkali metal corrosion, self-driven energy saving, and continuous and stable operation, making it suitable for the efficient gasification and utilization of biomass.

Description

Technical Field

[0001] This invention belongs to the technical field of biomass combustion equipment, specifically, it relates to a bottom-inlet biomass pellet combustion device and ignition method. Background Technology

[0002] Biomass gasification furnaces can convert seemingly insignificant agricultural and forestry wastes such as straw and wood chips into clean combustible gas, and based on this, provide diversified energy services from heat and electricity to high-end chemical raw materials. However, biomass combustion technology is still under development and has some inherent defects and engineering challenges that still need to be solved.

[0003] The core issues arising from this mainly focus on tar treatment and slagging corrosion caused by alkali metals. Tar is one of the most intractable problems in the gasification process. It not only clogs and corrodes pipelines but also reduces gasification efficiency. Improperly treated tar-containing wastewater can cause secondary pollution. Furthermore, biomass (especially straw) is rich in alkali metals such as potassium and sodium, which precipitate at high temperatures. These precipitated alkali metals adhere to the inner walls of the equipment like glue, forming a hard slagging layer that blocks the slag discharge port. Simultaneously, these substances react chemically with metals, severely corroding the equipment and leading to decreased heat transfer efficiency or even shutdown.

[0004] In view of this, the applicant proposes an improved technical solution based on the double-shell structure and the existing two-stage downdraft gasifier structure to improve the technical difficulties of the current biomass gasifier. Summary of the Invention

[0005] The main objective of this invention is to provide a bottom-intake biomass pellet combustion device and ignition method, which aims to improve combustion efficiency, reduce pollution emissions, and minimize losses due to alkali metal corrosion.

[0006] To achieve the above objectives, the present invention provides a bottom-inlet biomass pellet combustion device, comprising:

[0007] The outer casing has a rotatable hopper at the top, and the bottom of the outer casing is sealed to the base.

[0008] The inner furnace component is coaxially connected to the hopper at the top. The inner furnace component is located at the axis of the outer shell and is rotatably mounted at the top of the oxidation throat tube. The bottom of the oxidation throat tube is connected to the reducer.

[0009] The gas supply pipe has an igniter installed at the top, which is located at the center of the inner furnace. The gas supply pipe is installed inside the reducer and is suitable for introducing gasifying agent.

[0010] In this process, the combustible gas produced by the thermal reaction of biomass flows into the gap between the inner furnace and the outer shell through the reducer. Then, it is ignited by the spark plug installed on the outside of the outer shell, which drives the inner furnace to rotate and heat the inner furnace.

[0011] Furthermore, the inner furnace components include:

[0012] The pyrolyzer has several fan blades welded to its outer side, and the bottom of the pyrolyzer is rotatably connected to and communicates with the top of the oxidation throat tube;

[0013] The dryer has a feed inlet at the top center, and its bottom is coaxially fixed to the pyrolyzer.

[0014] A heat transfer grate is installed between the pyrolyzer and the dryer. During use, the combustible gas generated after reduction drives the fan blades to rotate the inner furnace components, causing the ignition stirring rod to rotate synchronously, thereby achieving automatic stirring and uniform heating of the biomass pellets without the need for an additional drive mechanism. At the same time, the combustible gas flows and releases heat in the double shell sandwich, achieving self-insulation of the furnace body and improving thermal efficiency and reaction stability.

[0015] Furthermore, the igniter includes:

[0016] The base is connected to the air supply pipe at the bottom and the assembly ball head is welded to the top.

[0017] A number of ignition stirring rods are provided, and the end of each ignition stirring rod is welded and fixed to the assembly ball head and a pulse igniter is installed.

[0018] The auger, with its end threadedly connected to the assembled ball head, passes through the heat transfer grate and is inserted into the feed hopper;

[0019] Each ignition stirring rod has multiple nozzles, which are connected to the assembled ball head through the ignition stirring rod and ignited outwards by a pulse igniter. This allows for the placement of an ignition stirring rod with pulse ignition at the center of the inner furnace components. The flame directly bakes the material inside the dryer, rapidly evaporating free water and bound water. In conjunction with the auger rotating synchronously with the furnace body, continuous feeding is achieved, forming an integrated continuous process of "drying-ignition-pyrolysis". This process features fast ignition start-up and good operational continuity.

[0020] Furthermore, the gas supply pipe includes a cross pipe, a straight pipe, and a flange joint. The connecting base is sealed and fixedly connected to the flange joint. The flange joint is located at the top of the straight pipe, and the bottom of the straight pipe is connected to the center of the cross pipe. The cross pipe is installed inside the reducer and passes through the outer shell to communicate with the outside.

[0021] Furthermore, the oxidation throat includes a throat, a thrust bearing, a gas supply pipe, and a connecting flange. A pair of gas supply pipes are symmetrically arranged on both sides of the throat. The oxidation throat adopts a narrow-diameter throat structure to form a strong turbulent high-temperature zone. Combined with the symmetrical gas supply pipes on the sides and the cross-shaped pipe at the bottom for multi-point gas supply, the gasifying agent is mixed more thoroughly with biochar and tar, the endothermic reduction reaction is more complete, the CO, H2, and CH4 content in the combustible gas is increased, and the calorific value of the gas is improved.

[0022] A thrust bearing is installed at the top of the throat tube and is connected to the bottom of the pyrolyzer through the thrust bearing;

[0023] A connecting flange is provided at the bottom of the throat tube, and the connecting flange is installed on the reducer by fasteners.

[0024] Furthermore, the restorer includes:

[0025] The reaction vessel has a grate hinged at the bottom, and the grate is coaxially connected to the lever. By setting the grate and the external lever at the bottom of the reducer, and in conjunction with the slag discharge trough on the base, slag can be easily cleaned during operation, realizing continuous feeding-reaction-gas production-slag discharge, which is suitable for large-scale biomass gasification utilization scenarios.

[0026] Four mounting holes for the tube seat are provided, with the interior suitable for inserting a cross-shaped pipe. The four mounting holes are symmetrically arranged on the side of the reaction vessel, and an exhaust port is provided between adjacent mounting holes.

[0027] Furthermore, the base includes

[0028] The slag discharge seat has a slag discharge trough on the side, which is connected to the bottom of the reaction vessel through the grate. The top of the slag discharge seat has several ventilation holes.

[0029] The air inlet seat is fixedly connected to the slag discharge seat at the top, and the air inlet seat is connected to the outer shell through several vent holes;

[0030] The air inlet seat has an air inlet groove on its side, which connects to the vent hole and supplies air to the outer shell when the spark plug ignites the combustible gas. Specifically, through the air inlet structure at the bottom of the base, in conjunction with the thermocouple and spark plug on the outside of the outer shell, the combustible gas in the interlayer is automatically ignited to supplement heat when the furnace temperature is below 800℃, maintaining a high-temperature reaction environment, further inhibiting the condensation of alkali metals on the furnace wall, and ensuring a continuous and stable gasification reaction.

[0031] The beneficial effects of applying the technical solution of this invention are as follows:

[0032] The technical solution disclosed in this invention adopts a double-shell layout with an outer shell and inner furnace components, combined with a two-stage gasification structure consisting of a high-temperature pyrolysis zone and a lower reduction zone in a downdraft throat. A high-temperature zone of 800–1200°C is formed at the throat location, enabling deep secondary pyrolysis of tar in the combustible gas, significantly reducing the tar content of the crude gas, simplifying the subsequent gas purification system, and lowering equipment investment and operating costs. Furthermore, it creatively uses the gas supply pipe (a cross-shaped pipe combined with a straight pipe) as a low-temperature heat exchange surface, introducing a low-temperature gasifying agent to maintain a relatively low pipe wall temperature. Gaseous alkali metals from biomass thermal desorption preferentially condense and slag on the surface of the gas supply pipe, thereby preventing alkali metal adhesion and corrosion of the inner furnace components, oxidation throat, and reducer inner wall, significantly reducing the erosion of core reaction components by high-temperature alkali metals and extending equipment lifespan.

[0033] This invention discloses an ignition method using a bottom-intake biomass pellet combustion device, comprising the following processes:

[0034] The biomass pellets are loaded into the hopper, and then gas is introduced into the cross pipe. When the gas enters the assembly head, it enters the ignition stirring rod to release flames outward.

[0035] Biomass pellets enter the dryer through a hopper, and flames pass through a heat transfer grate to evaporate the free water and bound water in the material, thereby drying the biomass pellets.

[0036] After drying, the biomass pellets are ignited and enter the pyrolysis unit. At this point, a low-temperature gasifying agent is introduced into the cross-shaped pipe, converting the biomass into char, tar, and combustible gas. The specific reaction formula is as follows: ; ;

[0037] The gasifying agent is supplied to the throat through a gas supply pipe. The biochar and the supplied gasifying agent are burned to produce CO, and some of the hydrogen produced by cracking is reacted with oxygen to produce water. The specific reaction formula is as follows: ; ; ; ;

[0038] The reaction products in the throat, under an oxygen-deficient environment at 800–1000°C, enter the reaction vessel and undergo multiple endothermic reduction reactions, increasing... , , The content of [something] and the formation of combustible gas; the main reaction of gasification is: ; ; ;

[0039] Combustible gas enters the gap between the inner furnace components and the outer shell, and drives the fan blades to rotate the pyrolyzer, which in turn ignites the stirring rod to stir and bake the biomass pellets. At the same time, the combustible gas transfers heat to the inner furnace components, oxidation throat and reducer, causing the alkali metals precipitated in the biomass to condense on the cross pipe and straight pipe.

[0040] Furthermore, a thermocouple thermometer is installed on the outside of the outer casing. When the temperature inside the outer casing is below 800°C, the spark plug ignites the combustible gas between the inner furnace components and the outer casing.

[0041] Furthermore, the vaporizing agent is low-temperature air not exceeding zero degrees Celsius.

[0042] The beneficial effects of applying the technical solution of this invention are as follows:

[0043] This ignition method, through a segmented process of "drying-pyrolysis-oxidation-reduction," combined with a bottom-inlet structure and a low-temperature vaporizing agent design, achieves the following technical effects:

[0044] High-efficiency tar pyrolysis: Through the high-temperature throat zone design of the oxidation throat tube, the tar is fully pyrolyzed at 800-1200℃, which significantly reduces the tar content of the crude gas and reduces the cost of gas purification.

[0045] Effective recovery of alkali metals: The low-temperature gas supply pipe is used as a condensation surface, so that gaseous alkali metals condense and adhere, avoiding furnace corrosion and extending the service life of the equipment.

[0046] Self-driven energy-saving operation: The internal furnace components are rotated by the impact fan blades of combustible gas, without the need for additional power. At the same time, the combustion of combustible gas achieves self-heating of the furnace body, improving energy utilization efficiency.

[0047] Continuous and stable operation: Through continuous feeding by auger and controllable slag discharge by grate, continuous processing of biomass pellets is achieved, which is suitable for industrial application scenarios. Attached Figure Description

[0048] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0049] Figure 1 A perspective view of the biomass pellet combustion device with bottom air intake provided by the present invention is disclosed;

[0050] Figure 2 A top view of the biomass pellet combustion device with bottom air intake provided by the present invention is disclosed;

[0051] Figure 3 for Figure 2 Sectional view at AA;

[0052] Figure 4 for Figure 2 Sectional view at BB;

[0053] Figure 5 This is a perspective view of the base disclosed in this invention;

[0054] Figure 6 This is a perspective view of the reducer disclosed in this invention;

[0055] Figure 7 This is a three-dimensional view of the oxide throat disclosed in this invention;

[0056] Figure 8 This is a perspective view of the air supply seat tube disclosed in this invention;

[0057] Figure 9 This is a perspective view of the igniter disclosed in this invention;

[0058] Figure 10 This is a perspective view of the inner furnace component disclosed in this invention;

[0059] The above figures include the following reference numerals:

[0060] 1 Outer shell; 2 Feed hopper; 3 Inner furnace components; 31 Cracker; 32 Heat transfer grate; 33 Dryer; 34 Feed inlet; 35 Several fan blades; 4 Oxidation throat; 41 Throat; 42 Thrust bearing; 43 Gas supply pipe; 44 Connecting flange; 5 Gas supply seat pipe; 51 Cross pipe; 52 Straight pipe; 53 Flange joint; 6 Reducer; 61 Reaction vessel; 62 Seat pipe mounting hole; 63 Exhaust hole; 64 Dial lever; 65 Grate; 7 Ignitioner; 71 Connecting base; 72 Assembled ball head; 73 Ignition stirring rod; 74 Spray hole; 75 Screwdriver; 8 Spark plug; 9 Base; 91 Slag discharge seat; 92 Slag discharge trough; 93 Vent hole; 94 Air inlet groove; 95 Air inlet seat. Detailed Implementation

[0061] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0062] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0063] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0064] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in sequences other than those illustrated or described herein.

[0065] Furthermore, the terms “including” and “having” and any variations thereof are intended to cover non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, which is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0066] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., may be used here to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figure. It should be understood that spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device as described in the figure.

[0067] For example, if a device in the accompanying drawings is inverted, a device described as "above" or "on top of" other devices or structures will subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below". The device may also be positioned differently, rotated 90 degrees, or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0068] See Figures 1 to 10 As shown, the present invention provides a bottom-inlet biomass pellet combustion device, which mainly adopts a double-shell structure and combines a two-stage bottom-suction gasifier structure to reduce the tar content in the crude gas and reduce the cost of the gas purification system. At the same time, the gas supply pipe 5 is used to contact the biomass pellets in the reaction process to condense and recover alkali metals, thereby reducing equipment wear caused by alkali metal corrosion.

[0069] The technical solutions disclosed in this invention will be described below by way of specific embodiments.

[0070] In one specific embodiment disclosed in this invention, such as Figures 2-4 The main structure of the bottom-intake biomass pellet combustion device includes an outer shell 1, an inner furnace component 3, and a gas supply pipe 5. A hopper 2 is rotatably mounted on the top of the outer shell 1, and an exhaust port is located at the tangential side of the outer shell 1 to release clean combustible gas. The bottom of the outer shell 1 is sealed to a base 9, through which air can be supplied to the outer shell 1 to promote combustion, maintain the chemical reaction temperature within the combustion device, and prevent precipitated alkali metals from adhering to the inner walls of the inner furnace component 3, the oxidation throat 4, and the reducer 6. It should be noted that the inner furnace component 3 is located on the axis of the outer shell 1 and rotatably mounted on top of the oxidation throat 4. The bottom of the oxidation throat 4 is connected to the reducer 6. Simultaneously, the top of the inner furnace component 3 is coaxially connected to the hopper 2. During the combustible gas conversion process, the combustible gas produced by the thermal reaction of biomass flows through the reducer 6 into the gap between the inner furnace component 3 and the outer shell 1. Then, it is ignited by a spark plug 8 installed on the outside of the outer shell 1, driving the inner furnace component 3 to rotate and heating it. In addition, an igniter 7 is provided at the center of the inner furnace 3. The igniter 7 is located at the top of the gas supply pipe 5, which is installed inside the reducer 6 and is adapted to introduce a gasifying agent so that the biomass can be pyrolyzed into char, tar and combustible gas in the inner furnace 3 to provide reactants for subsequent secondary pyrolysis.

[0071] In a specific embodiment of the present invention, the igniter 7 includes a connecting base 71, an ignition stirring rod 73, and an auger 75. The connecting base 71 is fixedly connected to the gas supply pipe 5, and the top of the connecting base 71 is welded to the assembly ball head 72. In this embodiment, the assembly ball head 72 is a hollow structure, and multiple ignition stirring rods 73 are welded to the outside of the assembly ball head 72. Each ignition stirring rod 73 is equipped with a pulse igniter. After the biomass pellets enter the inner furnace component 3, the gas supply pipe 5 supplies gas to the assembly ball head 72. At the same time, the gas is ignited by the pulse igniter through the ignition stirring rod 73. Specifically, each ignition stirring rod 73 has multiple nozzles 74, which are connected to the assembly ball head 72 through the ignition stirring rod 73 and ignite the flame outward through the pulse igniter. This heats the free water and bound water in the biomass pellets or materials, thereby achieving water evaporation.

[0072] In this embodiment, as Figure 8The gas supply pipe 5 includes a cross pipe 51, a straight pipe 52, and a flange joint 53. The connecting base 71 is sealed and fixedly connected to the flange joint 53. The flange joint 53 is located at the top of the straight pipe 52. The bottom of the straight pipe 52 is connected to the center of the cross pipe 51. The cross pipe 51 is installed inside the reducer 6 and passes through the outer shell 1 to connect with the outside. Combustible gas or low-temperature gasifying agent is simultaneously introduced into the four ports of the cross pipe 51 by the gas pump. When the low-temperature gasifying agent is introduced, the gaseous alkali metal released from the biomass particles encounters the relatively low-temperature heat exchange surface (the pipe wall of the cross pipe 51 and the straight pipe 52). Even if its surface temperature is as high as 500-600°C, it will quickly condense and form a "glue" with strong adhesion, which then captures fly ash and gradually evolves into a hard slag layer that is difficult to remove. This prevents the alkali metal from adhering to the inner furnace parts 3, the oxidation throat pipe 4, and the inner wall of the reducer 6.

[0073] In some embodiments, the inner furnace component 3 includes a pyrolyzer 31 and a dryer 33. The pyrolyzer 31 is welded with several fan blades 35 on its outer side. The bottom of the pyrolyzer 31 is rotatably connected to and communicates with the top of the oxidation throat 4. The combustible gas released from the reducer 6 can drive the pyrolyzer 31 to rotate through the fan blades 35. The bottom of the pyrolyzer 31 is coaxially fixed with the bottom of the dryer 33, thereby driving the dryer 33 and rotating synchronously with it. On the other hand, a heat transfer grate 32 is provided between the pyrolyzer 31 and the dryer 33. An inlet 34 is provided at the top center of the dryer 33. The inlet 34 is fixedly connected to the discharge hopper 2. The biomass that has been baked can be reduced in volume or cracked and broken, and can enter the pyrolyzer 31 through the heat transfer grate 32 to participate in the pyrolysis reaction to generate combustible gas or tar.

[0074] In this embodiment, the top of the assembled ball head 72 is threadedly connected to the end of the auger 75, and the auger 75 passes through the heat transfer grate 32 and is inserted into the feed hopper 2, so that during the rotation of the pyrolyzer 31, biomass pellets are continuously fed into the dryer 33 along the auger 75.

[0075] In some embodiments, the oxidation throat 4 includes a throat 41, a thrust bearing 42, a gas supply pipe 43, and a connecting flange 44. A pair of gas supply pipes 43 are symmetrically arranged on both sides of the throat 41. The outer diameter of the throat 41 is smaller than that of the inner furnace component 3 and the reducer 6, forming a throat-type downward suction structure. This results in a gradually narrowing throat region or "V"-shaped area in the middle of the throat 41, forming a high-temperature throat region (800-1200°C). The gasifying agent is injected from the upper part of the throat region, which helps to further crack the tar in the combustible gas, resulting in a lower tar content in the combustible gas. On the other hand, the top of the throat 41 is equipped with a thrust bearing 42, which is connected to the bottom of the cracker 31 to allow the cracker 31 to rotate. The bottom of the throat 41 is provided with a connecting flange 44 to install the throat 41 onto the reducer 6 using fasteners.

[0076] In some embodiments, such as Figure 6 The reducer 6 includes a reaction vessel 61, mounting holes 62, and vent holes 63. A grate 65 is hinged to the bottom of the reaction vessel 61, and the grate 65 is coaxially connected to a lever 64. The lever 64 extends into the outer shell 1; by moving the lever 64, the grate 65 can be opened to pour out the residue. Four symmetrical mounting holes 62 are provided on the side of the reaction vessel 61. These holes are used to insert a cross-shaped pipe 51 to fix the gas supply pipe 5. Vent holes 63 are provided between adjacent mounting holes 62 to guide the final high-calorific-value, low-tar combustible gas into the gap between the outer shell 1 and the inner furnace component 3.

[0077] Based on the previous embodiment, such as Figure 5 The base 9 includes a slag discharge seat 91 and an air inlet seat 95, which are connected in series. The slag discharge seat 91 located at the upper end of the air inlet seat 95 has a slag discharge trough 92 on its side. The slag discharge trough 92 is connected to the bottom of the reaction vessel 61 through the grate 65. When the grate 65 is opened, the slag can be poured out into the slag discharge seat 9 and recovered from the slag discharge trough 92. The top of the air inlet seat 95 is fixedly connected to the slag discharge seat 91. The top of the slag discharge seat 91 is provided with several vent holes 93. The air inlet seat 95 is connected to the outer shell 1 through several vent holes 93. The side of the air inlet seat 95 is provided with an air inlet groove 94, which is connected to the vent holes 93. When the spark plug 8 ignites the combustible gas, it provides air to the outer shell 1, increases the temperature inside the outer shell 1, and prevents the gaseous alkali metals that are released from the condenser from condensing. At the same time, after the spark plug 8 ignites the combustible gas, it can also drive the pyrolyzer 31 to rotate, so that the material is fully burned in the pyrolyzer 31 to improve the conversion efficiency of biomass pellets.

[0078] Based on the same inventive concept, this invention discloses an ignition method for a bottom-intake biomass pellet combustion device, which is described below in conjunction with the appendix. Figure 1-10The specific implementation process of this method will be explained in detail.

[0079] First, step one, device preparation and initial feeding, is performed. The bottom-inlet biomass pellet combustion device used in this method has a main structure including core components such as an outer shell 1, inner furnace 3, gas supply pipe 5, oxidation throat 4, reducer 6, igniter 7, and base 9. The outer shell 1 has a rotatable feed hopper 2 at its top and a discharge port at its side tangential section for releasing clean combustible gas. Its bottom is sealed to the base 9. The inner furnace 3 is coaxially mounted inside the outer shell 1 and rotatably installed on top of the oxidation throat 4. The bottom of the oxidation throat 4 is connected to the reducer 6. The igniter 7 is located at the center of the inner furnace 3 and on top of the gas supply pipe 5, which is installed inside the reducer 6 to introduce the gasifying agent. The base 9 is used to supply air into the device to maintain the reaction temperature and prevent alkali metals from adhering to the internal structure of the furnace.

[0080] Specifically, before the ignition operation begins, the assembly and sealing checks of the device are completed to ensure that all pipelines and flange connections are reliable, the grate 65 is in the closed state, and auxiliary components such as spark plug 8 and thermocouple thermometers are in standby mode. The biomass pellets to be processed are loaded into the feed hopper 2 to complete the initial feeding preparation.

[0081] In step two, initial ignition and biomass drying are performed. Combustible gas is introduced into the cross pipe 51 of the gas supply pipe 5. The gas is transported along the cross pipe 51 and straight pipe 52 to the connecting base 71 of the igniter 7. After entering the assembly ball head 72, it is distributed to each ignition stirring rod 73 and sprayed outward through the nozzles 74 on the ignition stirring rod 73. It is ignited by the pulse igniter installed on the ignition stirring rod 73 to form a stable flame. Under the action of gravity, the biomass pellets enter the dryer 33 of the inner furnace component 3 through the feed hopper 2. The flame generated by the igniter 7 passes through the heat transfer grate 32 between the pyrolyzer 31 and the dryer 33 in the inner furnace component 3, baking the biomass pellets in the dryer 33, causing the free water and bound water in the material to evaporate rapidly, completing the pre-treatment of the biomass pellets. At the same time, the auger 75 rotates continuously under the drive of the pyrolyzer 31, stably feeding the biomass pellets in the feed hopper 2 into the dryer 33, realizing continuous feeding.

[0082] After drying, the biomass pellets undergo step three, where they are ignited by a flame and enter the pyrolysis and gasification agent switching stage. The biomass then passes through the heat transfer grate 32 into the pyrolysis unit 31 below, where a pyrolysis reaction occurs. At this time, the medium flowing through the cross-shaped pipe 51 is switched, introducing a low-temperature gasification agent (low-temperature air) at no more than 0°C. The gasification agent is transported upwards along the straight pipe 52, providing the reaction conditions for the pyrolysis reaction. Within a temperature range of 200–600°C, the biomass pellets undergo pyrolysis in the pyrolysis unit 31, converting into char, tar, and combustible gas. The core reaction formula is as follows: ; ;

[0083] Meanwhile, the low-temperature gasifying agent continuously flows through the pipe walls of the cross pipe 51 and the straight pipe 52. The gaseous alkali metals released from the biomass come into contact with the relatively low-temperature heat exchange surface (pipe wall temperature 500-600℃), and quickly condense to form an adhesive slag layer, which adheres to the surface of the gas supply seat pipe 5. This prevents the alkali metals from corroding the inner furnace components 3, the oxidation throat pipe 4, and the inner wall of the reducer 6, while also capturing fly ash and reducing fly ash emissions.

[0084] In step four, the biochar, tar, and combustible gas produced by pyrolysis enter downwards into the oxidation throat 4. Simultaneously, the gasifying agent is injected into the throat region from the upper middle part of the throat 41 through the gas supply pipes 43 symmetrically arranged on both sides of the oxidation throat 4. The outer diameter of the oxidation throat 41 is smaller than that of the inner furnace component 3 and the reducer 6, forming a throat-type downward suction structure. This creates a high-temperature environment of 800–1200°C in the throat region, causing further secondary pyrolysis of the tar in the combustible gas. During this secondary pyrolysis process, the tar content in the crude gas can be significantly reduced, decreasing the cost of the subsequent gas purification system. Furthermore, in this stage, the biochar and gasifying agent undergo a combustion reaction, and some of the H2, CO, and CH4 produced by pyrolysis also participate in combustion. The core reaction formula is as follows: ; ; ; ;

[0085] In step five, the biomass enters the reduction and gas production stage of the reducer. The reaction products (high-temperature flue gas, unreacted char, combustible gas, etc.) in the oxidation throat 41 flow downwards into the reaction vessel 61 of the reducer 6 under an oxygen-deficient environment of 800-1000℃. Multiple sets of endothermic reduction reactions occur in the reducer 6, further increasing the content of CO, H2, and CH4 in the combustible gas, generating high-calorific-value, low-tar combustible gas. The core reaction formula is as follows: ; ; ;

[0086] After the reduction reaction is complete, the generated combustible gas is introduced into the annular gap between the inner furnace component 3 and the outer shell 1 through the exhaust port 63 on the reducer 6. Then, the combustible gas entering the annular gap in step six impacts the fan blades 35 on the outside of the pyrolyzer 31, driving the pyrolyzer 31 and the dryer 33 to rotate synchronously. During the rotation of the pyrolyzer 31, the central igniter 7 rotates synchronously, causing the ignition stirring rod 73 to stir the biomass particles in the furnace, improving the uniformity of material heating and the fullness of reaction, while continuously baking the biomass particles, enhancing the drying and pyrolysis effects. At the same time, the combustible gas flows in the annular gap, transferring heat to the inner furnace component 3, the oxidation throat 4, and the reducer 6, maintaining the reaction temperature in the furnace, further promoting the precipitation of alkali metals in the biomass, and causing the precipitated gaseous alkali metals to condense on the surface of the low-temperature gas supply pipe 5 (cross pipe 51 and straight pipe 52). The alkali metals can be recovered by replacing the gas supply pipe 5.

[0087] A thermocouple thermometer is installed on the outside of the outer shell 1 to monitor the temperature inside the annular gap in real time. When the temperature inside the outer shell 1 is below 800°C, the spark plug 8 automatically ignites the combustible gas inside the annular gap. The heat generated by the combustion raises the temperature inside the furnace and further drives the pyrolyzer 31 to rotate, thereby improving the conversion efficiency of biomass pellets. At the same time, the air inlet seat 95 of the base 9 supplies air into the outer shell 1 through the air inlet groove 94 and the vent hole 93 to provide oxygen for the combustion of combustible gas, maintain the high temperature environment inside the furnace, and prevent alkali metals from condensing on the inner wall of the furnace.

[0088] Finally, step seven is completed, and slag removal and continuous operation are carried out. After the biomass pellets undergo pyrolysis, oxidation, and reduction reactions, the remaining residue falls onto the grate 65 at the bottom of the reducer 6. When it is necessary to clean the residue, the lever 64 extending to the outside of the outer shell 1 is moved, causing the grate 65 to rotate and open. The residue falls through the grate 65 into the slag discharge seat 91 of the base 9, and is finally discharged and recycled from the slag discharge trough 92, achieving continuous and stable operation of the device.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bottom-intake biomass pellet combustion device, characterized in that, include: The outer shell (1) has a rotatable hopper (2) on its top, and the bottom of the outer shell (1) is sealed to the base (9); The inner furnace component (3) is coaxially connected to the feed hopper (2) at its top. The inner furnace component (3) is located at the axis of the outer shell (1) and is rotatably mounted on the top of the oxidation throat tube (4). The bottom of the oxidation throat tube (4) is connected to the reducer (6). Gas supply pipe (5) with an igniter (7) installed on top, the igniter (7) being located at the center of the inner furnace component (3), the gas supply pipe (5) being installed inside the reducer (6) and adapted to introduce gasifying agent; The combustible gas generated by the biomass thermal reaction flows into the gap between the inner furnace component (3) and the outer shell (1) through the reducer (6). The combustible gas is ignited by the spark plug (8) installed on the outside of the outer shell (1) and expands to drive the inner furnace component (3) to rotate, while heating the inner furnace component (3).

2. The biomass pellet combustion device with bottom air intake as described in claim 1, characterized in that, The inner furnace component (3) includes: The pyrolyzer (31) has several fan blades (35) welded on its outer side. The bottom of the pyrolyzer (31) is rotatably connected to and communicates with the top of the oxidation throat tube (4). The dryer (33) has a feed inlet (34) at the center of its top, and the bottom of the dryer (33) is coaxially fixed with the pyrolyzer (31). A heat transfer grate (32) is provided between the pyrolyzer (31) and the dryer (33).

3. The biomass pellet combustion device with bottom air intake as described in claim 2, characterized in that, The igniter (7) includes: The connecting base (71) is fixedly connected to the air supply seat pipe (5) at the bottom and has an assembly ball head (72) welded to the top. Ignition stirring rods (73), in several quantities, and the end of each of the ignition stirring rods (73) is welded and fixed to the assembly ball head (72) and a pulse igniter is installed thereon; The auger (75) is threaded at its end to the assembled ball head (72), and the auger (75) passes through the heat transfer grate (32) and is inserted into the feed hopper (2); Each of the ignition stirring rods (73) has multiple nozzles (74), which are connected to the assembled ball head (72) through the ignition stirring rods (73) and ignite the flame outward through a pulse igniter.

4. The biomass pellet combustion device with bottom air intake as described in claim 3, characterized in that, The gas supply pipe (5) includes a cross pipe (51), a straight pipe (52) and a flange joint (53). The connecting base (71) is sealed and fixedly connected to the flange joint (53). The flange joint (53) is located at the top of the straight pipe (52). The bottom of the straight pipe (52) is connected to the center of the cross pipe (51). The cross pipe (51) is installed inside the reducer (6) and passes through the outer shell (1) to communicate with the outside.

5. The biomass pellet combustion device with bottom air intake as described in claim 4, characterized in that, The oxidation throat (4) includes a throat (41), a thrust bearing (42), an air supply pipe (43) and a connecting flange (44), and a pair of air supply pipes (43) are symmetrically arranged on both sides of the throat (41). The top of the throat (41) is equipped with a thrust bearing (42) and is connected to the bottom of the pyrolyzer (31) through the thrust bearing (42); The bottom of the throat (41) is provided with a connecting flange (44), which is installed on the reducer (6) by fasteners.

6. The biomass pellet combustion device with bottom air intake as described in claim 5, characterized in that, The reducer (6) includes: The reaction vessel (61) has a grate (65) hinged to the bottom, and the grate (65) is coaxially connected to the lever (64). Four mounting holes (62) are provided, the interior of which is suitable for inserting a cross pipe (51). The four mounting holes (62) are symmetrically arranged on the side of the reaction vessel (61), and an exhaust hole (63) is provided between adjacent mounting holes (62).

7. The biomass pellet combustion device with bottom air intake as described in claim 6, characterized in that, The base (9) includes The slag discharge seat (91) has a slag discharge trough (92) on its side. The slag discharge trough (92) is connected to the bottom of the reaction vessel (61) through the grate (65). The top of the slag discharge seat (91) is provided with several ventilation holes (93). The air inlet seat (95) is fixedly connected to the slag discharge seat (91) at its top, and the air inlet seat (95) is connected to the outer shell (1) through a plurality of the ventilation holes (93); The air intake seat (95) has an air intake groove (94) on its side. The air intake groove (94) is connected to the vent (93). When the spark plug (8) ignites the combustible gas, air is supplied to the outer shell (1) through the air intake groove (94).

8. An ignition method, using the bottom-intake biomass pellet combustion device as described in claim 7, characterized in that, The process includes the following: Biomass pellets are loaded into the feed hopper (2), and then gas is introduced into the cross pipe (51). When the gas enters the assembly ball head (72), it enters the ignition stirring rod (73) to release flames outward. Biomass pellets enter the dryer (33) through the feed hopper (2), and the flame evaporates the free water and bound water in the material through the heat transfer grate (32) to dry the biomass pellets; After the biomass pellets are dried, they are ignited and enter the pyrolyzer (31). At this time, a low-temperature gasifying agent is introduced into the cross pipe (51), and the biomass is converted into char, tar and combustible gas. The temperature range is 200 to 600°C. The gasifying agent is sent into the throat (41) through the gas supply pipe (43). The biochar and the supplied gasifying agent are burned to produce CO2 and H2 produced by partial cracking. H2 reacts with oxygen to produce water. The temperature range is 800 to 1200℃. The reaction products in the throat (41) enter the reaction vessel (61) at 800–1000°C in an oxygen-deficient environment and undergo multiple endothermic reduction reactions to increase [the product's properties]. , , The content of [something] and the formation of combustible gas; the main reaction of gasification is: ； ； ； Combustible gas enters the gap between the inner furnace component (3) and the outer shell (1) and drives the fan blade (35) to rotate the pyrolyzer (31), causing the ignition stirring rod (73) to stir and bake the biomass pellets. At the same time, the combustible gas transfers heat to the inner furnace component (3), the oxidation throat (4) and the reducer (6), causing the alkali metals precipitated in the biomass to condense on the cross pipe (51) and the straight pipe (52).

9. The ignition method as described in claim 8, characterized in that, A thermocouple thermometer is installed on the outside of the outer shell (1). When the temperature inside the outer shell (1) is below 800°C, the spark plug (8) ignites the combustible gas between the inner furnace component (3) and the outer shell (1).

10. The ignition method as described in claim 8, characterized in that, The vaporizing agent is low-temperature air at a temperature not higher than 0°C.

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