Feeding system for circulating fluidized bed boilers mixing biomass and solid waste

Abstract

The present invention provides a feeding system for a circulating fluidized bed boiler for the co-firing of biomass and solid waste, comprising a ground with a settling pit and a coal bunker, a lifting cover installed at the upper end of the settling pit, a receiving hopper provided in the settling pit, a liftable dust cover with a telescopic dust suction pipe provided on the side of the receiving hopper, a feeding pipe connected to the dust suction pipe provided at the bottom of the receiving hopper, the output end of the feeding pipe being connected to a separation bin and an air induced flow station in sequence, a coal feeding belt provided above the coal bunker, a coal plow provided on the coal feeding belt near the coal bunker loading port, a coal lowering chute provided above the coal feeding belt, and a separating bin lowering chute extending into the interior of the coal lowering chute. The present invention solves the dust pollution problem of biomass fuel and solid waste fuel during the unloading and transportation process by pneumatically conveying air intake, and at the same time, by adjusting the gas-to-material ratio in the vertical pipeline, provides a new process route for material transportation and a unique, irreversible channel for blending biomass fuel and solid waste fuel.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum transportation, in particular to a feeding system for a circulating fluidized bed boiler for co-firing biomass and solid waste. Background Art

[0002] Circulating fluidized bed (CFB) combustion technology, developed from bubbling beds in the late 1970s, has undergone decades of technological refinement and now boasts numerous advantages, including wide fuel compatibility, high combustion efficiency, low pollutant emissions, strong stability, and a simple overall boiler structure. CFB boilers are widely used in thermal power plants with complex fuel systems, and their application to the combustion of biomass and solid waste fuels offers significant advantages.

[0003] Optimizing the energy structure, vigorously developing clean energy, and orderly disposing of solid waste have become essential for achieving this goal. Circulating fluidized bed boilers are a reliable fuel for the co-firing of biomass and solid waste. However, specialized technologies are required to address issues such as how to blend biomass and solid waste fuels, control the blending ratio, and measure the blending amount.

[0004] Patent application number CN202211265101.2 uses positive pressure air-driven sorting mobile feeding equipment to feed materials, and a dust collector is installed on the storage bin. However, the storage bin is located above the boiler return feeder or coal drop pipe, which does not solve the dust pollution problem caused by ground unloading of biomass or solid waste fuel.

[0005] Patent application number CN201811436977.2 uses a belt scale for weighing biomass powder and performing online calorific value analysis, transmitting the measured data to a centralized control room. While belt scales are relatively accurate for weighing biomass fuel, they are not limited to biomass loading. The belt on which the belt scale is installed can also be used to load coal, making it a separate channel and prone to confusion during measurement.

[0006] Patent number ZL202111234300.2 utilizes a switching mechanism between negative pressure separation chambers, with chamber A receiving pressure to absorb material and chamber B releasing pressure to discharge material. This switching mechanism achieves continuous loading. This method is suitable for vehicle-mounted equipment, but it cannot overcome the drawback of frequent switching between separation chambers due to small chamber volumes when loading circulating fluidized bed boilers.

[0007] Patent application number CN202210278893.0 uses spiral feeders on both sides to feed the materials, which are then mixed and then burned in the shell. This device mixes the materials more evenly, but still requires a large installation space and a more complex feeding and mixing mechanical structure.

[0008] Patent application number cn208886819u proposes dividing the biomass silo into different zones and achieving feeding stability by controlling the feed rates of these zones. Feeding different silos, or different zones within the same silo, at different rates addresses, to some extent, the difficulty in adjusting the amount of biomass or solid waste entering the furnace. However, for circulating fluidized bed boilers, the large volume of the coal silo and the limited space in front of the furnace make it difficult to incorporate a sufficiently large biomass or solid waste silo. Therefore, the patent's operability is poor.

[0009] Patent application number CN201921385242.1 utilizes an activator, feeder, discharge belt, and screw feeder at the bottom of the biomass silo to achieve continuous, quantitative feeding. This patent varies the feed rate by adjusting the mechanical speed of the conveyor, offering high controllability. However, its drawbacks include complex equipment, a lengthy process, a large footprint, and a high failure rate. Summary of the Invention

[0010] In response to the shortcomings of the existing technology, the present invention provides a feeding system for the co-firing of biomass and solid waste in a circulating fluidized bed boiler, which solves the problems of dust pollution, uneven gas-to-mass ratio in the negative pressure conveying pipeline, lack of separate channel metering for biomass fuel and solid waste fuel, continuous feeding of biomass fuel and solid waste fuel by negative pressure conveying, uneven blending of biomass fuel and solid waste fuel with traditional fuels, and difficulty in adjusting the blending amount of biomass fuel and solid waste fuel.

[0011] To achieve the above objectives, the present invention is implemented through a scheme: a feeding system for a circulating fluidized bed boiler for co-firing biomass and solid waste, comprising a ground with a sedimentation pit and a coal bunker, a top cover being installed at the upper end of the sedimentation pit, the outer peripheral surface of the top cover being sleeved with a waterproof concave-convex gasket, a grate plate being provided in the middle of the lower end of the top cover, a receiving hopper installed in the sedimentation pit being provided in the middle of the lower end of the grate plate, a liftable dust cover connected to the top cover being provided at the upper right end of the receiving hopper, a feeding pipe being connected to the bottom of the receiving hopper, an output end of the feeding pipe being fixedly connected to the input port of the separation bin, the output end of the separation bin being connected to the input end of the air-induced flow station by a pipeline, a telescopic dust suction pipe connected to the feeding pipe being installed on the dust cover, a coal feeding belt being provided above the coal bunker, a coal plow being installed on the coal feeding belt near the coal bunker loading port, a lower coal chute being provided above the coal feeding belt, and the lower coal chute of the separation bin extending to the interior of the lower coal chute.

[0012] Preferably, a hydraulic cylinder is installed at the lower end of the top cover, and the top cover and the hydraulic cylinder are connected by a tie rod. When driven by a drive motor, the hydraulic cylinder pushes up the top cover, the dust cover rises, and the dust suction pipe extends.

[0013] Preferably, the feeding pipe is provided with an air supply pipe, and the air supply pipe is equipped with a valve, and the valve opening can be adjusted according to the change of the vacuum degree of the air-inducing logistics station.

[0014] Preferably, the feeding pipe is connected to the dust suction pipe through a dust suction pipe tee, and the side wall of the dust suction pipe is provided with a branch connected to the air inlet end of the feeding pipe. When the air-induced logistics station transports biomass and solid waste, the air inhaled comes from the dust suction pipe, and the dust suction pipe is connected to the dust suction port of the dust cover to inhale the dust raised when the receiving hopper receives the material.

[0015] Preferably, a coal supply belt is provided above the lower coal chute input port, the lower coal chute output port is installed at the guide chute input port, the coal supply belt is provided below the guide chute, and a coal feeder is installed at the lower part of the coal bunker.

[0016] Preferably, a rotary feeding valve is installed at the lower part of the separation bin, and the blending ratio of the biomass or solid waste fuel is controlled by adjusting the rotation speed of the rotary feeding valve.

[0017] Preferably, there are multiple separation bins that can alternately receive and discharge materials.

[0018] Preferably, the lower coal chute receives the raw coal transported by the upper coal belt, and the raw coal is mixed with the biomass and solid waste transported by the lower coal chute in the lower coal chute and falls into the guide chute, and the mixed fuel is distributed to each furnace coal bunker through the coal feeding belt, coal plow, and bunker port.

[0019] Preferably, a plurality of weighing sensors are fixedly welded at the lower end of the separation bin, and the weighing sensors are installed at the base of the separation bin to measure the weight of the full bin and the empty bin, thereby realizing accurate weighing of the blending amount. A level meter is installed in the separation bin to measure the level change in the separation bin to calculate the volume change, thereby calculating the weight change.

[0020] The present invention provides a feeding system for a circulating fluidized bed boiler for the co-firing of biomass and solid waste. It has the following beneficial effects:

[0021] The present invention solves the problem of air intake for pneumatic conveying and dust pollution during the unloading and transportation of biomass fuel and solid waste fuel. At the same time, by adjusting the gas-to-material ratio in the vertical pipeline, the technical problem of large-lift continuous pneumatic feeding is solved, a new process route is provided for material transportation, and a unique and irreversible channel is provided for blending biomass fuel and solid waste fuel. Measuring the blending amount in this channel is of great significance for boiler combustion control and incremental utilization of solid waste and biomass fuel, which can improve the economic benefits of power generation units. Moreover, fossil energy is non-renewable when used, and blending biomass and solid waste fuel is simpler and easier, with scalable social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A perspective view of the present invention;

[0023] Figure 2This is a side view of the separation chamber structure of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of the present invention in a non-raised state;

[0025] Figure 4 It is a schematic structural diagram of the present invention in a raised state.

[0026] Among them, 1. Ground; 2. Waterproof concave and convex gasket; 3. Top cover; 4. Grate plate; 5. Receiving hopper; 6. Tie rod; 7. Dust cover; 8. Dust suction pipe; 9. Feeding pipe; 10. Dust suction pipe tee; 11. Hydraulic cylinder; 12. Hydraulic pipe; 13. Drive motor; 14. Air supply pipe; 15. Coal feeding belt; 16. Coal discharging chute; 17. Material guide chute; 18. Coal feeding belt; 19. Coal plow; 20. Loading port; 21. Coal bunker; 22. Coal feeder; 23. Coal feeder belt; 24. Separation bin; 25. Material level meter; 26. Return air pipe; 27. Rotary valve; 28. Air-induced logistics station; 29. ​​Weighing sensor; 30. Discharging chute. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Example:

[0029] Please see the attached Figure 1 -Attached Figure 4 The embodiment of the present invention provides a feeding system for a circulating fluidized bed boiler for co-firing biomass and solid waste, comprising a ground 1 with a sedimentation pit, a coal bunker 21 installed on the ground 1, a coal feeder and a separation bin 24 provided at the feeding port of the coal bunker 21, a waterproof concave-convex gasket 2 installed on the upper end of the ground 1, a top cover 3 fixedly sleeved on the middle part of the upper end of the waterproof concave-convex gasket 2, a grate plate 4 provided on the middle part of the lower end of the top cover 3, a receiving hopper 5 installed in the sedimentation pit provided on the middle part of the lower end of the grate plate 4, and a dust cover connected to the top cover 3 provided on the upper right end of the receiving hopper 5. 7. The receiving hopper 5 is provided with a feeding pipe 9, the output end of the feeding pipe 9 is fixedly connected to the input end of the separation bin 24, and the dust suction port of the dust cover 7 is fixedly connected with a telescopic dust suction pipe 8. The dust suction pipe 8 includes an inner tube and an outer tube that are slidably connected. The inner tube is connected to the dust suction port of the dust cover 7, and the outer tube output port of the dust suction pipe 8 is welded to the input port of the dust suction pipe tee 10 of the feeding pipe 9. A branch is also provided on the side wall of the dust suction pipe 8, and the branch is connected to the air inlet end of the feeding pipe 9. The output port of the feeding pipe 9 is fixedly sleeved at the input port of the separation bin 24.

[0030] The top cover 3 is connected to a hydraulic cylinder 11 through a tie rod 6. The hydraulic cylinder 11 is driven by a drive motor 13 to push up the top cover 3, thereby driving the dust cover 7 to rise and fall and the dust suction pipe 8 to extend and retract.

[0031] Tie bars 6 are installed on the right side of the floor 1, and a dust hood 7 is installed at the discharge point. This hood 7 rises during discharge and sinks below the floor when not discharging. This hood 7 uses the negative pressure air generated by the air-entrained logistics station main unit 28 to absorb dust in the feed pipe 9. Dust generated by dumping biomass fuel or solid waste fuel enters the feed pipe 9 through the dust suction pipe 8 at the top of the hood 7, through the dust suction pipe tee 10 and branch line, and is then induced by air into the separation chamber 24 along with the material.

[0032] The feeding pipe 9 is provided with an air supply pipe 14, and a valve is installed on the air supply pipe 14, and the valve opening can be adjusted according to the change of the vacuum degree of the air-inducing logistics station 28.

[0033] When the air-entrained logistics station 28 transports biomass and solid waste, the air inhaled comes from the dust suction pipe 8, which is connected to the upper part of the dust cover 7 to inhale the dust raised when the receiving hopper 5 receives the material, in order to solve the problem of uneven gas-to-material ratio in the large-lift vertical negative pressure conveying pipeline.

[0034] The present invention is provided with three adjustable air supply ports. The angles or openings of the three air supply ports are adjusted according to the vacuum degree in the feeding pipe 9, so that the gas-to-material ratio in the feeding pipe is always at an optimal ratio, effectively avoiding material sedimentation and pipe blockage caused by insufficient air volume or vacuum degree.

[0035] These three adjustable air supply points are: an inclined plate with an adjustable angle is set at the air inlet end of the lower three-way pipe of the receiving hopper 5. By adjusting the angle of the inclined plate, the flow rate of the material in the lower part of the pipeline is accelerated, and the upper material falls into the lower part by gravity and is led to the feeding pipe 9 by the accelerated air; the discharge end of the lower three-way pipe of the receiving hopper is provided with inclined pipe air supply on both sides. The diameter of the air supply pipes 14 on both sides is about 1 / 2 of the diameter of the feeding pipe. The air supply pipes 14 on both sides are equipped with electric butterfly valves. The opening of the electric butterfly valve is linked to the vacuum degree in the feeding pipe 9. When the vacuum degree in the feeding pipe 9 is too high, the opening of the electric butterfly valve of the air supply pipe 14 increases, and vice versa.

[0036] A valve is provided at the connection point between the lower part of the dust suction pipe 8 and the feeding pipe 9, that is, the dust suction pipe tee 10, to control the opening of the dust suction pipe 8. When the vacuum degree in the feeding pipe 9 is too high, the valve opening is increased, and vice versa.

[0037] A return air pipe 26 connected to the air-inducing logistics station (28) is fixedly sleeved in the middle of the right side of the separation bin 24. A level meter 25 is installed in the separation bin 24. A rotary valve 27 is fixedly sleeved in the middle of the lower end of the level meter 25. A discharge chute 30 is fixedly installed at the output port of the rotary valve 27. The vertical feeding pipeline set at the same time can only be used to transport materials with a density below 0.8 cubic meters / ton.

[0038] The output port of the lower chute 30 extends to the input port of the lower coal chute 16, and the upper coal belt of the coal loader also extends above the lower coal chute 16. The biomass and other solid waste transported by the lower chute 30 are mixed with the raw coal transported by the upper coal belt 15 in the lower coal chute 16.

[0039] The output port of the lower coal chute 16 is installed at the input port of the guide trough 17. A coal feeding belt 18 is provided in the middle of the lower end of the guide trough 17. A plurality of coal plows 19 are provided on the upper part of the coal feeding belt 18. A loading port 20 is installed in the middle of the lower end of the coal plow 19. The loading port 20 is located above the coal bunker 21. A coal feeder 22 is installed at the lower part of the coal bunker 21. After the raw coal enters the lower coal chute 16, it is fully mixed with the biomass fuel or solid waste fuel and absorbs most of the dust. The mixed fuel falls into the guide trough 17 for shaping and is then input into the coal bunker 21 of each furnace along the coal feeding belt 18. Dust pollution is suppressed to a large extent. At the same time, the feeding end of the coal feeding belt 18 completes the mixing, and the original equipment of the boiler, such as the coal feeding belt 18, the coal plow 19 and the loading port 20, are utilized to distribute the mixed fuel to multiple boilers.

[0040] A rotary feeding valve 27 is installed at the lower part of the separation chamber 24 , and the mixing ratio of the biomass or solid waste fuel is controlled by adjusting the rotation speed of the rotary feeding valve 27 .

[0041] A plurality of weighing sensors 29 are fixedly welded to the lower end of the separation bin 24. The weighing sensors 29 are installed above the material guide trough 17. A material level meter 25 is installed inside the separation bin 24. The material level meter 25 calculates the weight of the material in the bin by measuring the volume when the bin is full.

[0042] Rotating valve 27 rotates to empty the bin, thereby obtaining the weight of the bin material, that is, the weight of the fuel added to the furnace. Similarly, weighing sensor 29 measures the weight of the full bin and the weight of the empty bin, and the difference between the two gives the weight of the fuel added to the furnace. Two or more separation bins 24 work alternately to discharge the material.

[0043] After three drops and blending, the biomass or solid waste and fuel coal are mixed more evenly, and the mixed fuel is fed into the furnace. This largely solves the problem of uneven flame distribution in the furnace caused by the easy combustion of biomass, the general easy combustion of fuel coal, and the less easy combustion of solid waste. It also solves the problems of backflow of flue gas at the feed port and fire in the silo caused by the single biomass fuel being fed into the furnace.

[0044] First time: biomass fuel or solid waste fuel enters the lower coal chute 16 through the lower chute 30 and is mixed with the raw coal transported by the upper coal belt 15 in the chute;

[0045] Second time: the coal plow 19 scrapes the mixed fuel from the first mixing into the coal bunker 21, and the fuel is thrown down for the second mixing;

[0046] For the third time, the coal feeder belt 22 transports the mixed fuel into the furnace and drops it into the coal drop pipe. This is the third mixing.

[0047] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A feeding system for a circulating fluidized bed boiler for the co-firing of biomass and solid waste, comprising a ground (1) with a settling pit and a coal bunker (21), characterized in that: The upper end of the sedimentation pit is provided with a top cover (3), the outer peripheral surface of the top cover (3) is sleeved with a waterproof concave-convex gasket (2), the middle part of the lower end of the top cover (3) is provided with a grate plate (4), the middle part of the lower end of the grate plate (4) is provided with a receiving hopper (5) installed in the sedimentation pit, the upper right end of the receiving hopper (5) is provided with a liftable dust cover (7) connected to the top cover (3), the bottom of the receiving hopper (5) is connected to a feeding pipe (9), the output end of the feeding pipe (9) is fixedly connected to the input port of the separation bin (24), and the separation bin ( 24) output end is connected to the input end of the air-induced flow station (28) by a pipeline, a telescopic dust suction pipe (8) connected to the feeding pipe (9) is installed on the dust cover (7), a coal feeding belt (18) is provided above the coal bunker (21), a coal plow (19) is installed on the coal feeding belt (18) near the bunker loading port (20) of the coal bunker (21), a lower coal chute (16) is provided above the coal feeding belt (18), and the lower material chute (30) of the separation bin (24) extends to the interior of the lower coal chute (16); The feeding pipe (9) is provided with an air supply pipe (14), and the air supply pipe (14) is provided with a valve, and the valve opening can be adjusted according to the change of the vacuum degree of the air-inducing logistics station (28); The feeding pipe (9) is connected to the dust suction pipe (8) through a dust suction pipe tee (10), and a branch connected to the air inlet end of the feeding pipe (9) is provided on the side wall of the dust suction pipe (8). When the air-inducing logistics station (28) transports biomass and solid waste, the air inhaled comes from the dust suction pipe (8), and the dust suction pipe (8) is connected to the dust suction port of the dust cover (7) to inhale the dust raised when the receiving hopper (5) receives the material; A plurality of weighing sensors (29) are fixedly welded to the lower end of the separation bin (24). The weighing sensors (29) are installed at the base of the separation bin (24) to measure the weight of the full bin and the empty bin, thereby achieving accurate weighing of the blending amount. A material level meter (25) is installed in the separation bin (24) to measure the material level change in the separation bin to calculate the volume change, thereby calculating the weight change.

2. The feeding system for the circulating fluidized bed boiler for the co-firing of biomass and solid waste according to claim 1, characterized in that: A hydraulic cylinder (11) is installed at the lower end of the top cover (3), and the top cover (3) and the hydraulic cylinder (11) are connected via a tie rod (6). When driven by a drive motor (13), the hydraulic cylinder (11) pushes the top cover (3) upward, the dust cover (7) rises, and the dust suction pipe (8) extends.

3. The feeding system for the circulating fluidized bed boiler for the co-firing of biomass and solid waste according to claim 1, characterized in that: An upper coal belt (15) is further provided above the input port of the lower coal chute (16); the output port of the lower coal chute (16) is installed at the input port of the guide trough (17); the coal feeding belt (18) is provided below the guide trough (17); and a coal feeder (22) is installed at the lower part of the coal bunker (21).

4. The feeding system for the circulating fluidized bed boiler for the co-firing of biomass and solid waste according to claim 1, characterized in that: A rotary feeding valve (27) is installed at the lower part of the separation bin (24), and the mixing ratio of the biomass or solid waste fuel is controlled by adjusting the rotation speed of the rotary feeding valve (27).

5. The feeding system for the circulating fluidized bed boiler for the co-firing of biomass and solid waste according to claim 3, characterized in that: There are multiple separation bins (24) that can alternately receive and discharge materials.

6. The feeding system for the circulating fluidized bed boiler for the co-firing of biomass and solid waste according to claim 5, characterized in that: The lower coal chute (16) receives the raw coal transported by the upper coal belt (15). The raw coal is mixed with the biomass and solid waste transported by the lower material chute (30) in the lower coal chute (16) and falls into the guide trough (17). The mixed fuel is distributed to the coal bunkers (21) of each furnace through the coal feeding belt (18), the coal plow (19) and the bunker port (20).

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