A multi-stage air distribution and ash recycling device for a biomass combustion boiler
By using a multi-stage air distribution and ash recycling device in a biomass combustion boiler, the problems of low combustion efficiency and ash waste are solved, and the full combustion of fuel and resource utilization of waste are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZAOZHUANG JIANYANG THERMAL POWER CO LTD
- Filing Date
- 2025-08-22
- Publication Date
- 2026-07-21
AI Technical Summary
Existing biomass combustion boilers have low combustion efficiency, resulting in serious fuel waste. The unburned portion of the ash is directly discarded, increasing the cost of solid waste treatment.
It adopts a multi-stage air distribution design and ash recycling. The combustion efficiency is improved by vertical air supply at the bottom and oblique air supply at the top. The unburned ash is separated by a screening machine and recycled. The fine ash is used for brick making or agricultural soil improvement.
It improves the combustion efficiency of biomass boilers, reduces fuel waste, realizes the resource utilization of solid waste, and reduces operating costs.
Smart Images
Figure CN224534299U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of boilers, and in particular to a multi-stage air distribution and ash recycling device for biomass combustion boilers. Background Technology
[0002] Biomass energy, as an important component of clean and renewable energy, releases carbon dioxide during combustion, which can be absorbed by plant photosynthesis, achieving "carbon neutrality." It is one of the key pathways to replace fossil energy under the "dual carbon" goal.
[0003] However, existing biomass boilers suffer from core defects in actual operation, such as low combustion efficiency and serious fuel waste. Most existing biomass boilers use a single-stage air supply method, resulting in uneven air distribution in the fuel bed and incomplete fuel combustion. The ash residue after combustion contains 10%-15% unburned carbon particles. Existing devices often discard the ash residue directly as solid waste, which not only wastes valuable fuel resources but also increases the cost of solid waste treatment, severely limiting its efficiency and promotion. Utility Model Content
[0004] The purpose of this utility model is to provide a multi-stage air distribution and ash recycling device for biomass combustion boilers. Through the integrated design of precise air distribution and ash recycling, it solves the problems of incomplete fuel combustion, ash waste, and unstable operation, thereby improving the efficiency and environmental performance of biomass boilers.
[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A multi-stage air distribution and ash recycling device for a biomass combustion boiler includes a furnace body. A feeding device is installed on the left side of the furnace body, and a chain grate is installed at the bottom inside. A bottom air blowing device is installed in the middle of the chain grate, and an upper air blowing device is installed above it. A horizontal baffle is fixed inside the furnace body below the chain grate. A screening machine is installed inside the furnace body below the baffle. The screening machine is located at the ash collection point on the lower right side of the chain grate. A fly ash conveyor belt is installed below the fly ash discharge port at the bottom of the screening machine, and a combustible material conveyor belt is installed below the large unburned particle discharge port on the left side.
[0006] Preferably, the feeding device includes a horizontal screw feeder and a hopper. The horizontal screw feeder is fixed to the left side of the furnace body, and the discharge end is located above the left side of the chain grate. The hopper is fixedly welded to the top of the horizontal screw feeder.
[0007] Preferably, the feeding device further includes a vertical spiral circulating feeder, which has a feed inlet at the bottom and a downwardly inclined feed pipe welded to the top. The outlet end of the feed pipe is located above the left side of the chain grate. A guide plate is provided between the left end of the combustible conveyor belt and the feed inlet, and the guide plate is inclined from the high point of the combustible conveyor belt to the low point of the feed inlet.
[0008] Preferably, the bottom air blowing device includes a bottom main air inlet pipe, a bottom air inlet pipe interface, a bottom pipe, and nozzles. The bottom main air inlet pipe is located on the front side of the furnace body, and a bottom air inlet pipe interface is welded to the top. The bottom main air inlet pipe has multiple bottom pipes distributed radially in the front-to-back direction. The bottom pipe is located in the middle of the chain grate, and upward-facing nozzles are distributed on the bottom pipe.
[0009] Preferably, the upper air blowing device includes an upper main air inlet pipe, an upper air inlet pipe interface, and an upper pipe. The upper main air inlet pipe is located on the front and rear sides of the furnace body, and the upper air inlet pipe interface is welded to the top. Multiple upper pipes are radially distributed on the upper main air inlet pipe. A diffuser nozzle is installed at the end of the upper pipe. The upper pipe is inclined downward toward the chain grate, and the angle between the upper pipe and the horizontal is 30°.
[0010] Preferably, a steam drum is also fixedly installed on the furnace body, an inlet pipe is fixedly installed on the outside of the steam drum, a downcomer pipe is fixedly installed on the furnace body below the steam drum, the downcomer pipe extends to the S-shaped water-cooled wall of the furnace body, the water-cooled wall extends and connects to the inside of the steam drum, and a steam pipe is fixedly installed at the top of the steam drum.
[0011] Preferably, a flue is fixedly installed on the furnace body, the flue is connected to a vertically downward downcomer, the end of the downcomer is connected to a horizontal pipe, a conical ash storage trough is provided at the bottom of the downcomer and the horizontal pipe, a material level sensor is provided in the ash storage trough, a circulating feed pipe is connected to the bottom of the ash storage trough and connected to the top of the screening machine, and a solenoid valve is installed on the circulating feed pipe.
[0012] Preferably, an ignition device is fixedly installed at the fuel inlet on the outside of the furnace body.
[0013] Preferably, a temperature sensor is fixedly installed above the furnace body.
[0014] Preferably, an oxygen sensor is fixedly installed above the furnace body.
[0015] This utility model has the following beneficial effects: 1. The system adopts a bottom vertical air supply and an upper oblique air supply method. The nozzles below the grate penetrate the fuel layer vertically upwards to provide sufficient oxygen for the combustion of fixed carbon at the bottom, avoiding fuel accumulation. The oblique nozzles on the side wall blow into the middle of the fuel layer, breaking the surface coking layer, releasing internal volatiles, and supplementing secondary oxygen, so that the fuel combustion is more complete. 2. The fine ash screened by the screening machine can be used for brick making or agricultural soil improvement, realizing the resource utilization of solid waste. The unburned large particulate fuel is sent back to the furnace through the combustible material conveyor belt and vertical screw circulating feeder, mixed with fresh fuel and re-burned, improving fuel utilization. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the appearance and structure of this utility model; Figure 2 This is a longitudinal sectional view of the furnace body of this utility model; Figure 3 This is a cross-sectional view of the structure of the layer blowing device and the upper layer blowing device of this utility model; Figure 4 This is a utility model Figure 2 Enlarged view of A in the middle; Icons: 1. Furnace body; 2. Feeding device; 21. Horizontal screw feeder; 22. Hopper; 23. Vertical screw circulating feeder; 231. Inlet; 232. Discharge pipe; 3. Chain grate; 4. Bottom layer air blowing device; 41. Bottom layer main air inlet pipe; 42. Bottom layer air inlet pipe interface; 43. Bottom layer pipe; 44. Nozzle; 5. Upper layer air blowing device; 51. Upper layer main air inlet pipe; 52. Upper layer air inlet pipe interface; 53. Upper layer pipe 6. Baffle plate; 7. Screening machine; 8. Fly ash conveyor belt; 9. Combustible material conveyor belt; 91. Guide plate; 10. Steam drum; 101. Downcomer pipe; 102. Water-cooled wall; 103. Water inlet pipe; 104. Steam pipe; 11. Smoke pipe; 111. Downcomer pipe; 112. Horizontal pipe; 113. Ash storage trough; 114. Circulating feed pipe; 115. Solenoid valve; 12. Ignition device; 13. Temperature sensor; 14. Oxygen sensor. Detailed Implementation
[0017] The embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this utility model.
[0018] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0019] like Figure 1-4As shown, in this embodiment, a multi-stage air distribution and ash recycling device for a biomass combustion boiler includes a furnace body 1, which is welded from Q235B high-temperature resistant steel plate and lined with a resistant material to withstand the high-temperature combustion environment. A feeding device 2 is installed on the left side of the furnace body 1, and a chain grate 3, made of Cr25Ni20 high-temperature alloy, is installed at the bottom inside, slowly transporting fuel from left to right. A bottom air blowing device 4 is installed in the middle of the chain grate 3, and an upper air blowing device 5 is installed above it. A horizontal partition 6 is fixed inside the furnace body 1 below the chain grate 3. The furnace body below the partition 6... 1 is equipped with a screening machine 7, which is a commercially available particulate matter screening machine. The specific size and model of the equipment can be flexibly selected according to the appropriate space. The screen of the screening machine 7 is a stainless steel woven mesh with a screen hole size of 5mm. The screen hole size can be adjusted according to the fuel type, such as 5mm for straw ash and 3mm for wood chip ash. It is used to separate ash and slag into two parts: fine ash and unburned large particles. The screening machine 7 is located at the ash drop area on the lower right side of the chain grate 3. A fly ash conveyor belt 8 is installed below the fly ash discharge port at the bottom of the screening machine 7, and a combustible material conveyor belt 9 is installed below the unburned large particle discharge port on the left side.
[0020] Specifically, the chain grate 3, screening machine 7, fly ash conveyor belt 8, and combustible material conveyor belt 9 are driven by geared motors. Each motor is powered by a control box and controlled by a PLC control system. The bottom air blowing device 4 and the top air blowing device 5 of the chain grate 3 form a multi-stage air duct, enabling efficient combustion of biomass pellets on the grate. The screening machine 7 can screen the slag falling from the chain grate 3, collecting unburned biomass pellets via the combustible material conveyor belt 9 for resource recycling and improved fuel utilization. The baffle 6 prevents fly ash from falling into the combustible material conveyor belt 9. The fly ash conveyor belt 8 is connected to a fly ash storage bin at its end for collecting fine ash, which can then be used for brick making, road paving, or agricultural soil improvement.
[0021] The feeding device 2 includes a horizontal screw feeder 21 and a hopper 22. The horizontal screw feeder 21 is fixed to the left side of the furnace body 1 through a flange, and the discharge end is located above the left side of the chain grate 3. The hopper 22 is fixedly welded to the top of the horizontal screw feeder 21.
[0022] Specifically, the hopper 22 is used to store biomass fuel pellets. The motor of the horizontal screw feeder 21 is powered by the control box and controlled by the PLC control system. The screw blades in the horizontal screw feeder 21 push the fuel pellets evenly to the left end of the chain grate 3 to realize the fuel transportation.
[0023] The feeding device 2 also includes a vertical spiral circulating feeder 23. The vertical spiral circulating feeder 23 has an inlet 231 at the bottom and a downwardly inclined discharge pipe 232 welded to the top. The outlet end of the discharge pipe 232 is located to the upper left of the chain grate 3. A guide plate 91 is provided between the left end of the combustible conveyor belt 9 and the inlet 231. The guide plate 91 is inclined from the high point of the combustible conveyor belt 9 to the low point of the inlet 231.
[0024] Specifically, the motor of the vertical spiral circulating feeder 23 is powered by the control box and controlled by the PLC control system. The end of the combustible material conveyor belt 9 automatically feeds the unburned fuel into the feed port 231 of the vertical spiral circulating feeder 23 through the guide plate 91, so that the unburned fuel can be automatically circulated and fed into the chain grate 3 for combustion.
[0025] The bottom air blowing device 4 includes a bottom main air inlet pipe 41, a bottom air inlet pipe interface 42, a bottom pipe 43, and nozzles 44. The bottom main air inlet pipe 41 is located on the front side of the furnace body 1, and the bottom air inlet pipe interface 42 is welded to the top. The bottom main air inlet pipe 41 has multiple bottom pipes 43 arranged radially in the front and rear directions. The bottom pipes 43 are located in the middle of the chain grate 3, and upward-facing nozzles 44 are distributed on the bottom pipes 43.
[0026] Specifically, the bottom air inlet 42 is supplied with air by an external high-pressure centrifugal fan. The high-pressure centrifugal fan distributes the air evenly to each nozzle 42, penetrates the chain grate 3 and enters the bottom of the fuel layer, providing sufficient oxygen. At the same time, it lifts the fuel to prevent it from piling up and accelerates the combustion of the fuel at the bottom of the fuel layer.
[0027] The upper air blowing device 5 includes an upper main air inlet pipe 51, an upper air inlet pipe interface 52, and an upper pipe 53. The upper main air inlet pipe 51 is located on the front and rear sides of the furnace body 1, and the upper air inlet pipe interface 52 is welded to the top. Multiple upper pipes 53 are radially distributed on the upper main air inlet pipe 51. A diffuser nozzle is installed at the end of the upper pipe 53. The upper pipe 53 is inclined downward and faces the chain grate 3. The angle between the upper pipe 53 and the horizontal is 30°.
[0028] Specifically, the upper air intake pipe interface 52 is connected to a medium-pressure centrifugal fan, and a diffuser nozzle is installed at the end of the upper pipe 53 to increase the coverage area of the air. The downward airflow agitates the fuel layer, breaks the surface coking layer, releases internal volatiles, and replenishes secondary oxygen to promote the combustion of volatiles and reduce black smoke.
[0029] A steam drum 10 is also fixedly installed on the furnace body 1. A water inlet pipe 103 is fixed on the outside of the steam drum 10. A downcomer pipe 101 is fixed on the outside of the furnace body 1 below the steam drum 10. The downcomer pipe 101 extends to the S-shaped water-cooled wall 102 of the furnace body 1. The water-cooled wall 102 extends and connects to the inside of the steam drum 10. A steam pipe 104 is fixed at the top of the steam drum 10.
[0030] Specifically, the feedwater pump injects softened water into the steam drum 10 through the inlet pipe 103. The water flows into the water-cooled wall 102 through the downcomer pipe 101, absorbs the heat energy generated by combustion in the furnace body 1, and gradually vaporizes to form saturated steam. The saturated steam rises to the top of the steam drum 10 and is transported to the steam turbine or heat exchanger through the steam pipe 104 for power generation or industrial heating.
[0031] A flue pipe 11 is fixedly installed on the furnace body 1. The flue pipe 11 is connected to a vertically downward downcomer pipe 111. The end of the downcomer pipe 111 is connected to a horizontal pipe 112. The horizontal pipe 112 can discharge flue gas from the chimney through a bag filter and an induced draft fan. A conical ash storage trough 113 is provided at the bottom of the downcomer pipe 111 and the horizontal pipe 112, so that the fly ash and impurities flowing through it can fall into the ash storage trough 113 automatically by gravity for collection. A material level sensor is installed in the ash storage trough 113. A circulating feed pipe 114 is connected to the bottom of the ash storage trough 113 and is connected to the top of the screening machine 7. A solenoid valve 115 is installed on the circulating feed pipe 114.
[0032] Specifically, the PLC is connected to the level sensor and solenoid valve 115 via a protocol. The flue gas generated by combustion, with a temperature of approximately 400°C, enters the flue gas downcomer 111 through the flue pipe 11. Due to the reduced airflow velocity, the fine ash in the flue gas falls into the ash storage tank 113 under gravity. When the ash content in the ash storage tank 113 reaches 80% of its capacity, the solenoid valve 115 automatically opens based on the level sensor monitoring. The fine ash then enters the top of the screening machine 7 through the circulating feed pipe 114, where it is screened together with the ash and slag falling from the chain grate 3.
[0033] An ignition device 12 is fixedly installed at the fuel inlet on the outside of the furnace body 1. The ignition device 12 is an electronic igniter controlled by a PLC control box. During ignition, the bottom air blowing device 4 is first activated to reduce the air volume by half, and then the ignition device 12 is turned on to generate a high-frequency spark. At the same time, a small amount of ignition fuel is fed in through the horizontal screw feeder 21. After the ignition fuel is ignited, the bottom air volume and feed volume are gradually increased to prevent the flame from going out.
[0034] A temperature sensor 13 is fixedly installed on the top of the furnace body 1.
[0035] An oxygen sensor 14 is fixedly installed on the top of the furnace body 1.
[0036] Specifically, through the PLC control system set in the control box, temperature sensor 13 monitors the furnace temperature, and oxygen sensor 14 monitors the oxygen content of the flue gas. The system automatically adjusts the air volume of the bottom high-pressure centrifugal fan and the top medium-pressure centrifugal fan. When the furnace temperature is below 800℃, the bottom air volume is increased; when the oxygen content of the flue gas is below 6%, the top air volume is increased to ensure stable boiler operation.
[0037] The working principle of this utility model is as follows: turn on the power of the control box, start the bottom air blowing device 4, turn on the ignition device 12, and feed the ignition fuel through the horizontal screw feeder 21. After the ignition fuel is ignited, gradually increase the bottom air volume and feed volume. Fresh fuel enters the horizontal screw feeder 21 through the hopper 22 and is evenly pushed to the left end of the chain grate 3. The chain grate 3 operates normally, conveying the fuel from left to right. The high-pressure air from the bottom blowing device 4 penetrates the fuel layer, lifts the fuel and provides oxygen, and fixes the carbon for complete combustion. The oblique air from the upper blowing device 5 stirs the fuel, breaks the coking layer, releases volatiles and replenishes oxygen, and the volatiles are completely burned. The ash after combustion falls from the right end of the chain grate 3 and enters the screening machine 7. The screening machine 7 separates the ash into fine ash and unburned large particles. The fine ash is conveyed through the fly ash conveyor belt 8 and used for brick making or agricultural soil improvement to realize the resource utilization of solid waste. The unburned large particles are sent back to the left end of the chain grate 3 through the combustible material conveyor belt 9 and the vertical screw circulating feeder 23, where they are mixed with fresh fuel and re-burned. The fine ash in the flue gas is sent back to the screening machine 7 through the ash storage trough 113 and the circulating feed pipe 114 to recover the unburned small particles. Water in the water-cooled wall 102 absorbs combustion heat energy, vaporizes to form saturated steam, and is transported to the steam turbine through the steam pipe 104 for electricity or heat exchange for heating.
[0038] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A multi-stage air distribution and ash recycling device for a biomass combustion boiler, comprising a furnace body (1), wherein a feeding device (2) is installed on the left side of the furnace body (1), and a chain grate (3) is installed at the lower part of the interior, characterized in that, The chain grate (3) is equipped with a bottom air blowing device (4) in the middle and an upper air blowing device (5) above it. A horizontal partition (6) is fixed in the furnace body (1) below the chain grate (3). A screening machine (7) is installed in the furnace body (1) below the partition (6). The screening machine (7) is located at the ash drop point on the lower right of the chain grate (3). A fly ash conveyor belt (8) is installed below the fly ash discharge port at the bottom of the screening machine (7). A combustible material conveyor belt (9) is installed below the large unburned particle discharge port on the left side.
2. The multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, The feeding device (2) includes a horizontal screw feeder (21) and a hopper (22). The horizontal screw feeder (21) is fixed to the left side of the furnace body (1), and the discharge end is located above the left side of the chain grate (3). The hopper (22) is fixedly welded to the top of the horizontal screw feeder (21).
3. The multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 2, characterized in that, The feeding device (2) also includes a vertical spiral circulating feeder (23). The vertical spiral circulating feeder (23) has an inlet (231) at the bottom and a downwardly inclined feed pipe (232) welded to the top. The outlet end of the feed pipe (232) is located to the upper left of the chain grate (3). A guide plate (91) is provided between the left end of the combustible conveyor belt (9) and the inlet (231). The guide plate (91) is inclined from the high point of the combustible conveyor belt (9) to the low point of the inlet (231).
4. The multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, The bottom air blowing device (4) includes a bottom main air inlet pipe (41), a bottom air inlet pipe interface (42), a bottom pipe (43), and a nozzle (44). The bottom main air inlet pipe (41) is located on the front side of the furnace body (1), and the bottom air inlet pipe interface (42) is welded to the top. The bottom main air inlet pipe (41) has multiple bottom pipes (43) in the front and rear directions distributed radially. The bottom pipes (43) are located in the middle of the chain grate (3), and the bottom pipes (43) have upward-facing nozzles (44) distributed on them.
5. A multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, The upper air blowing device (5) includes an upper main air inlet pipe (51), an upper air inlet pipe interface (52), and an upper pipe (53). The upper main air inlet pipe (51) is located on the front and rear sides of the furnace body (1), and the upper air inlet pipe interface (52) is welded to the top. The upper main air inlet pipe (51) has multiple upper pipes (53) radially distributed. A diffuser nozzle is installed at the end of the upper pipe (53). The upper pipe (53) is inclined downwards and faces the chain grate (3). The upper pipe (53) has an angle of 30° with the horizontal.
6. The multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, A steam drum (10) is also fixedly installed on the furnace body (1). A water inlet pipe (103) is fixed on the outside of the steam drum (10). A downcomer pipe (101) is fixed on the outside of the furnace body (1) below the steam drum (10). The downcomer pipe (101) extends to the S-shaped water-cooled wall (102) of the furnace body (1). The water-cooled wall (102) extends and connects to the inside of the steam drum (10). A steam pipe (104) is fixed at the top of the steam drum (10).
7. The multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, A flue (11) is fixedly installed on the furnace body (1). The flue (11) is connected to a vertically downward downcomer (111). A horizontal pipe (112) is connected to the end of the downcomer (111) and the horizontal pipe (112). A conical ash storage trough (113) is provided at the bottom of the downcomer (111) and the horizontal pipe (112). A material level sensor is provided in the ash storage trough (113). A circulating feed pipe (114) is connected to the bottom of the ash storage trough (113) and is connected to the top of the screening machine (7). A solenoid valve (115) is installed on the circulating feed pipe (114).
8. A multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, An ignition device (12) is fixedly installed at the fuel inlet on the outside of the furnace body (1).
9. A multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, A temperature sensor (13) is fixedly installed on the top of the furnace body (1).
10. A multi-stage air distribution and ash recycling device for a biomass combustion boiler according to claim 1, characterized in that, An oxygen sensor (14) is fixedly installed on the top of the furnace body (1).