Anti-backfire circulating fluidized bed boiler biomass particle front feeding system

Abstract

The utility model provides a kind of anti-backfire's circulating fluidized bed boiler biomass particle stove front feeding system, can be while isolating furnace positive pressure high temperature flue gas, biomass particles are stably sent into boiler furnace, ensure the stability and security of biomass power plant operation.Stove front biomass bunker outlet is connected with leg shutoff valve import, leg shutoff valve export is connected with leg star type feeding valve import, leg star type feeding valve export is connected with feeding screw import, into stove star valve export is connected with into stove shutoff valve import, into stove shutoff valve export is connected with boiler drop opening;The feeding system further includes into stove pneumatic double-layer flap valve and into stove small bunker;Feeding screw export is connected with into stove pneumatic double-layer flap valve import, into stove pneumatic double-layer flap valve export is connected with into stove small bunker import, into stove small bunker export is connected with into stove star valve import.

Description

Technical Field

[0001] This utility model relates to a biomass pellet pre-feeding system for circulating fluidized bed boilers that prevents backfire, and is mainly used in biomass power plants that use biomass pellets as fuel. Background Technology

[0002] Biomass, as a renewable energy source, is widely available, abundant, and renewable. Using it for power generation offers multiple comprehensive benefits, including improving the energy structure, optimizing energy consumption, reducing dependence on fossil fuels, and promoting stable social development. Circulating fluidized bed (CFB) boilers, through fluidized bed combustion, ensure thorough mixing and efficient combustion of biomass fuel within the furnace, effectively controlling pollutant generation. In the field of biomass incineration power generation, it exhibits significant advantages due to its unique fuel adaptability, high combustion efficiency, and low pollutant emissions. However, due to the structural characteristics of fluidized bed boilers, the biomass fuel feed pipe is typically designed close to the air distribution plate. However, the area near the feed port is often under positive pressure, making it easy for high-temperature flue gas to backflow through the biomass feed port into the furnace feed silo, potentially causing a fire. In previous projects, increasing the induced draft fan frequency was typically used to lower the furnace zero-pressure point to control backflow. However, because there are fewer measuring points in the lower part of the furnace and it is located in the dense phase combustion zone, negative pressure control is difficult in actual operation. Utility Model Content

[0003] This utility model aims to overcome the shortcomings of the prior art and provide a reasonably designed anti-backfire biomass pellet feed system for circulating fluidized bed boilers. It can stably feed biomass pellets into the boiler furnace while isolating the positive pressure high-temperature flue gas in the furnace, thus ensuring the stability and safety of biomass power plant operation.

[0004] The technical solution adopted by this utility model to solve the above problems is: a biomass pellet pre-furnace feeding system for a circulating fluidized bed boiler with anti-backfire capability, including a pre-furnace biomass silo, a feeding system, and a boiler discharge port. The feeding system includes a leg shut-off valve, a leg star-shaped feed valve, a feeding screw, a furnace inlet star valve, and a furnace inlet shut-off valve. The outlet of the pre-furnace biomass silo is connected to the inlet of the leg shut-off valve, the outlet of the leg shut-off valve is connected to the inlet of the leg star-shaped feed valve, the outlet of the leg star-shaped feed valve is connected to the inlet of the feeding screw, the outlet of the furnace inlet star valve is connected to the inlet of the furnace inlet shut-off valve, and the outlet of the furnace inlet shut-off valve is connected to the boiler discharge port. The feeding system further includes a furnace inlet pneumatic double-layer flap valve and a furnace inlet silo. The outlet of the feeding screw is connected to the inlet of the furnace pneumatic double-layer flap valve, the outlet of the furnace pneumatic double-layer flap valve is connected to the inlet of the furnace inlet silo, and the outlet of the furnace inlet silo is connected to the inlet of the furnace star valve.

[0005] This utility model also includes a silo top dust collector, which is installed on the top of the biomass silo in front of the furnace.

[0006] The feeding system described in this utility model consists of at least two units arranged side by side.

[0007] The volume of the furnace feed hopper described in this invention is slightly larger than the volume between the two valve discs of the furnace feed pneumatic double-layer flap valve.

[0008] Compared with the prior art, this utility model has the following advantages and effects: This system permanently isolates the furnace from the feeding system by introducing a pneumatic double-layer flap valve, thus isolating the positive pressure high-temperature flue gas in the furnace and preventing fires. However, due to the structural characteristics of the pneumatic double-layer flap valve, intermittent feeding will affect the stable combustion in the furnace. Therefore, a small feed hopper is introduced below the pneumatic double-layer flap valve, and the outlet of the small feed hopper is then converted into uniform feeding through a star valve. Attached Figure Description

[0009] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model. Detailed Implementation

[0010] To more clearly illustrate the specific embodiments of this utility model or the solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0011] This utility model embodiment includes a pre-furnace biomass silo 1, a silo top dust collector 2, a feeding system, and a boiler feed inlet 10. The feeding system includes a feed leg shut-off valve 3, a feed leg star feed valve 4, a feeding screw 5, a pneumatic double-layer flap valve for furnace entry 6, a small feed silo for furnace entry 7, a star valve for furnace entry 8, and a shut-off valve for furnace entry 9.

[0012] The dust collector 2 is installed on top of the biomass silo 1 in front of the furnace. The outlet of the feed leg of the biomass silo 1 is connected to the inlet of the feed leg shut-off valve 3, which is convenient for shutting off during maintenance. The outlet of the feed leg shut-off valve 3 is connected to the inlet of the feed leg star-shaped feed valve 4, which adjusts the feed rate through frequency conversion to adapt to changes in furnace load. The outlet of the feed leg star-shaped feed valve 4 is connected to the inlet of the feed screw 5, which delivers fuel to the front wall of the boiler. The outlet of the feed screw 5 is connected to the inlet of the pneumatic double-layer flap valve 6, which isolates the positive pressure in the furnace. The outlet of the pneumatic double-layer flap valve 6 is connected to the inlet of the small feed bin 7, which buffers intermittent feeding by the flap valve. The outlet of the small feed bin 7 is connected to the inlet of the star valve 8, which converts intermittent feeding to uniform feeding, ensuring stable boiler combustion. The furnace feed star valve 8 is connected to the inlet of the furnace feed shut-off valve 9, and the outlet of the furnace feed shut-off valve 9 is connected to the boiler feed port 10. The volume of the furnace feed hopper 7 is slightly larger than the volume between the two valve discs of the furnace feed pneumatic double-layer flap valve 6.

[0013] In this embodiment, there are two feeding systems, arranged side by side.

[0014] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A biomass pellet feed system for a circulating fluidized bed boiler with backfire prevention, comprising a biomass silo in front of the boiler, a feeding system, and a boiler feed inlet; the feeding system includes a leg shut-off valve, a leg rotary feed valve, a feeding screw, a furnace inlet rotary valve, and a furnace inlet shut-off valve; the outlet of the biomass silo in front of the boiler is connected to the inlet of the leg shut-off valve, the outlet of the leg shut-off valve is connected to the inlet of the leg rotary feed valve, the outlet of the leg rotary feed valve is connected to the inlet of the feeding screw, the outlet of the furnace inlet rotary valve is connected to the inlet of the furnace inlet shut-off valve, and the outlet of the furnace inlet shut-off valve is connected to the boiler feed inlet; characterized in that: The feeding system also includes a pneumatic double-layer flap valve for furnace inlet and a small hopper for furnace inlet; the feed screw outlet is connected to the inlet of the pneumatic double-layer flap valve for furnace inlet, the outlet of the pneumatic double-layer flap valve for furnace inlet is connected to the inlet of the small hopper for furnace inlet, and the outlet of the small hopper for furnace inlet is connected to the inlet of the star valve for furnace inlet.

2. The anti-backfire circulating fluidized bed boiler biomass pellet feed system according to claim 1, characterized in that: It also includes a silo top dust collector, which is installed on top of the biomass silo in front of the furnace.

3. The anti-backfire circulating fluidized bed boiler biomass pellet feed system according to claim 1 or 2, characterized in that: The feeding system consists of at least two units, arranged side by side.

4. The anti-backfire circulating fluidized bed boiler biomass pellet feed system according to claim 1 or 2, characterized in that: The volume of the furnace feed hopper is slightly larger than the volume between the two valve discs of the furnace feed pneumatic double-layer flap valve.

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