Device and method for reducing carbon content of fly ash of biomass boiler

Abstract

The invention belongs to the technical field of biomass power plant energy conservation, and provides a device and method for reducing the carbon content of biomass boiler fly ash, and the device comprises an inclined guide plate mounted at the lower part of a boiler body in the middle of two return strokes of a boiler, and an arc-shaped guide plate arranged at the lower part of the inclined guide plate; a rear boiler wall inclined ash baffle and a rear boiler wall transverse ash baffle are arranged on the rear boiler wall of the boiler second return stroke of the boiler body, an ash falling hopper is arranged at the bottom end of the boiler body, and a conveying fan is arranged on the ash falling hopper through a fly ash pneumatic conveying main pipe. Fly ash flowing along with flue gas is separated from the flue gas by means of inertia force and gravity and falls into an ash falling hopper under the flow guide effect of the inclined flow guide plate and the arc-shaped flow guide plate and the blocking effect of the rear furnace wall inclined ash blocking plate and the rear furnace wall transverse ash blocking plate, and then the collected fly ash is sent back into a hearth through a conveying fan to be combusted again. Therefore, the carbon content in the fly ash is reduced, and the purpose of improving the boiler efficiency is achieved.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving technology for biomass power plants, and particularly relates to a device and method for reducing the carbon content of fly ash from biomass boilers. Background Technology

[0002] Biomass direct combustion technology is the main way of large-scale application of biomass at present. However, existing biomass direct combustion power plants generally suffer from low operating levels and high carbon content in furnace ash. This is the reason for the reduction in boiler efficiency and an important way to improve its economic benefits.

[0003] Due to the significant differences in shape and size of biomass fuel, the combustion of the fuel in the furnace is uneven. Some small biomass particles are carried away from the furnace with the flue gas. As the temperature decreases, these fuel particles are difficult to burn completely, resulting in a significant increase in the carbon content of the ash. The unburned biomass particles carried away by the flue gas are separated in the second pass of the boiler and discharged outside the boiler as ash, which seriously affects the boiler efficiency. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a device and method for reducing the carbon content of fly ash in biomass boilers. The fly ash, flowing with the flue gas, is guided by inclined guide plates and arc-shaped guide plates, and blocked by inclined and transverse baffle plates on the rear furnace wall. It is then separated from the flue gas by inertia and gravity and falls into the ash hopper. A conveying fan then returns the collected fly ash to the furnace for re-combustion, thereby reducing the carbon content in the fly ash and improving boiler efficiency.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a device for reducing the carbon content of fly ash from biomass boilers, employing the following technical solution: A device for reducing the carbon content of fly ash from a biomass boiler includes an inclined guide plate installed at the lower part of the boiler body in the middle of the second pass of the boiler, and an arc-shaped guide plate disposed at the lower part of the inclined guide plate. The boiler body has a rear wall inclined baffle plate and a rear wall transverse baffle plate on the rear wall of the second pass boiler. A connecting cavity is installed on the rear wall inclined baffle plate. An ash hopper is provided at the bottom of the boiler body. A conveying fan is provided on the ash hopper through a fly ash pneumatic conveying main pipe. The fly ash flowing with the flue gas is separated from the flue gas by inertia and gravity under the guidance of the inclined guide plate and the arc-shaped guide plate, as well as the blocking effect of the inclined baffle plate and the transverse baffle plate of the rear furnace wall. It falls into the ash hopper and is then sent back into the furnace for re-combustion by the conveying fan.

[0006] Furthermore, the ash hopper is equipped with an ash baffle, the ash baffle is connected to an ash collection pipe, the ash collection pipe is connected to the fly ash pneumatic conveying main pipe, and the conveying fan is installed on the fly ash pneumatic conveying main pipe.

[0007] Furthermore, multiple fly ash collection pipes are arranged in parallel at the bottom end of the ash baffle, and each fly ash collection pipe is connected to the fly ash pneumatic conveying main pipe.

[0008] Furthermore, an ash discharge pipe is provided between the connecting cavity and the transverse ash baffle plate of the rear furnace wall.

[0009] Furthermore, the lower end of the inclined guide plate is inclined away from the ash baffle plate on the rear furnace wall.

[0010] Furthermore, the arc-shaped opening of the arc-shaped guide plate faces the inclined ash baffle plate of the furnace wall.

[0011] To achieve the above objectives, in a second aspect, the present invention also provides a method for reducing the carbon content of fly ash from biomass boilers, employing the following technical solution: A method for reducing the carbon content of fly ash from a biomass boiler, using the apparatus for reducing the carbon content of fly ash from a biomass boiler as described in the first aspect, includes: fly ash flowing with the flue gas is separated from the flue gas by inertia and gravity under the action of the inclined guide plate and the arc-shaped guide plate, and the blocking action of the inclined baffle plate and the transverse baffle plate of the rear furnace wall, and falls into the ash hopper; then the collected fly ash is sent back into the furnace for re-combustion by a conveying fan.

[0012] Furthermore, the fly ash carried in the flue gas is thrown towards the rear furnace wall by the inclined guide plate and the arc-shaped guide plate. The inclined baffle plate of the rear furnace wall blocks the fly ash rising along the rear furnace wall. A part of the fly ash blocked in the inclined baffle plate of the rear furnace wall falls into the ash pipe under the action of gravity, and then falls into the ash hopper through the ash pipe. Another part of the lighter fly ash blocked in the inclined baffle plate of the rear furnace wall enters the connecting cavity along the inclined baffle plate of the rear furnace wall under the action of the flue gas, and enters the ash pipe, and then falls into the ash hopper.

[0013] Furthermore, the ash discharge pipe passes through the horizontal baffle plate on the rear furnace wall. The horizontal baffle plate on the rear furnace wall will block the fly ash carried up along the rear furnace wall, and at the same time block the fly ash falling along the ash discharge pipe to prevent it from being carried away by the flue gas.

[0014] Furthermore, the fly ash falling into the ash hopper passes through multiple fly ash collection pipes and falls into the fly ash pneumatic conveying main pipe; the fly ash collected in the fly ash pneumatic conveying main pipe flows along the pneumatic conveying main pipe under the action of the conveying fan, and is finally sent back into the furnace.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The boiler body of this invention has a rear wall inclined baffle plate and a rear wall transverse baffle plate on the rear wall of the second pass boiler body. An ash hopper is provided at the bottom of the boiler body. A conveying fan is provided on the ash hopper through the fly ash pneumatic conveying main pipe. The fly ash flowing with the flue gas is guided by the inclined guide plate and the arc-shaped guide plate, and blocked by the rear wall inclined baffle plate and the rear wall transverse baffle plate. It is separated from the flue gas by inertia and gravity and falls into the ash hopper. Then, the conveying fan is used to send the collected fly ash back into the furnace for re-combustion, thereby reducing the carbon content in the fly ash and improving the boiler efficiency.

[0016] 2. In this invention, the fly ash flowing with the flue gas is separated from the flue gas by inertial force and gravity due to the action of the guide plate group, baffle plate, and ash drop pipe in the second pass space of the boiler, and finally falls into the ash hopper. Then, the collected fly ash is sent back to the furnace for re-combustion using a pneumatic conveying system, thereby reducing the carbon content of the fly ash and ultimately improving the combustion efficiency of the boiler.

[0017] 3. This invention is suitable for reducing the carbon content of fly ash in biomass boilers, which can improve the combustion efficiency of biomass boilers and has good economic benefits. Attached Figure Description

[0018] The accompanying drawings, which form part of this embodiment, are used to provide a further understanding of this embodiment. The illustrative embodiments and their descriptions are used to explain this embodiment and do not constitute an improper limitation of this embodiment.

[0019] Figure 1 This is a side sectional view of the device structure diagram of Embodiment 1 of the present invention; Figure 2 This is a front sectional view of the device structure schematic diagram of Embodiment 1 of the present invention; Figure 3 This is a comparison diagram of flue gas flow in Embodiment 1 of the present invention; The components include: 1. Boiler body; 2. Inclined guide vane; 3. Arc-shaped guide vane; 4. Connecting cavity; 5. Inclined baffle plate on the rear furnace wall; 6. Ash drop pipe; 7. Horizontal baffle plate on the rear furnace wall; 8. Ash drop hopper; 9. Ash drop baffle; 10. Fly ash collection pipeline; 11. Fly ash pneumatic conveying main pipe; and 12. Conveying fan. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] 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.

[0022] Biomass direct combustion technology is the main way of large-scale application of biomass at present. However, existing biomass direct combustion power plants generally suffer from low operating levels, high carbon content in furnace ash, and reduced boiler efficiency. Furthermore, due to high fuel costs, biomass power plants have relatively low profitability and struggle to survive. Energy conservation and consumption reduction in the biomass utilization process are important ways to improve the energy utilization efficiency of biomass power plants and enhance their economic benefits.

[0023] As described in the background section, such as Figure 3 As shown, due to the significant differences in the shape and size of biomass fuel, the combustion of the fuel in the furnace is uneven. Some small biomass particles are carried away from the furnace with the flue gas. As the temperature decreases, these fuel particles are difficult to burn completely, resulting in a significant increase in the carbon content of the ash. The carbon content of the ash in some biomass boilers can be as high as 30% to 40% or more. Many of these unburned biomass particles carried away by the flue gas are separated in the second pass of the boiler and discharged outside the boiler as ash, which seriously affects the boiler efficiency.

[0024] To solve the above problems, such as Figure 1 and Figure 2 As shown, one embodiment of the present invention provides a device for reducing the carbon content of fly ash from a biomass boiler, comprising a boiler body 1, an inclined guide plate 2, an arc-shaped guide plate 3, a connecting cavity 4, an inclined ash baffle plate on the rear furnace wall 5, an ash drop pipe 6, a transverse ash baffle plate on the rear furnace wall 7, an ash hopper 8, an ash drop baffle 9, a fly ash collection pipe 10, a fly ash pneumatic conveying main pipe 11, and a conveying fan 12, etc.

[0025] The inclined guide plate 2 is installed at the lower part of the boiler body 1 in the middle of the second pass of the boiler, and the lower end of the inclined guide plate 2 is connected to the arc-shaped guide plate 3; the inclined baffle plate 5 of the rear furnace wall is installed on the rear wall of the second pass of the boiler, and the two ends of the inclined baffle plate are connected to the ash drop pipes; the connecting cavity 4 is installed at the upper end of the inclined baffle plate; the transverse baffle plate 7 of the rear furnace wall is also installed on the rear furnace wall; the ash drop baffle 9 is installed in the ash drop hopper 8, and the lower part of the ash drop baffle 9 is connected to the ash collection pipe 10. The fly ash collection pipe 10 is connected to the fly ash pneumatic conveying main pipe 11, and the conveying fan 12 is installed on the fly ash pneumatic conveying main pipe 11. The collected fly ash is sent back into the furnace by the conveying fan 12.

[0026] The lower end of the inclined guide plate is tilted away from the inclined ash baffle plate on the rear furnace wall. The arc-shaped opening of the arc-shaped guide plate faces the inclined ash baffle plate on the rear furnace wall, thus achieving a guiding function. Specifically, the inclined guide plate 2 and the arc-shaped guide plate 3 installed in the lower section of the intermediate furnace wall in the second pass of the boiler together form a guide plate group, which guides the flue gas containing fly ash in the second pass of the boiler to the lower part of the front furnace wall. Under the action of inertial force, some of the fly ash is thrown down to the lower part of the front furnace wall and finally falls into the ash hopper 8 along the furnace wall.

[0027] like Figure 3 As shown, under the action of the guide plate assembly consisting of the inclined guide plate 2 and the arc-shaped guide plate 3, the flow direction of the flue gas is more biased towards the bottom of the second pass of the boiler. Figure 3 The dashed line represents the original flue gas flow direction, and the solid line represents the flue gas flow direction after the addition of the guide vanes. Figure 2 As shown, the vertical arrows indicate the flow direction of fly ash particles; in other words, the flue gas will travel around a larger outer circle, and the fly ash in the flue gas will be thrown onto the walls (including the bottom furnace wall and the rear furnace wall) under the action of centrifugal force.

[0028] The inclined baffle plate 5 installed on the rear wall of the boiler's second pass will block the fly ash thrown towards the furnace wall by the guide plate assembly. Since the inclined baffle plate 5 is arranged at an angle, part of the fly ash blocked in the inclined baffle plate falls into the ash discharge pipe 6 under the action of gravity, and the fly ash falls into the ash hopper 8 through the ash discharge pipe 6. Another part of the lighter fly ash blocked in the inclined baffle plate 5 enters the connecting cavity 4 installed on the upper part of the inclined baffle plate 5 under the carry of flue gas, and then enters the ash discharge pipe 6 and falls into the ash hopper 8.

[0029] The rear furnace wall transverse baffle plate 7, installed on the rear wall of the boiler's second pass, is located below the ash discharge pipe 6. The ash discharge pipe 6 passes through the rear furnace wall transverse baffle plate 7. The rear furnace wall transverse baffle plate 7 can block the fly ash carried up along the rear furnace wall and also block the fly ash falling along the ash discharge pipe 6, preventing it from being carried away by the flue gas.

[0030] The ash baffle 9 installed in the ash hopper 8 together with the rear furnace wall forms the ash hopper. The fly ash falling into the ash hopper 8 passes through multiple fly ash collection pipes 10 and falls into the fly ash pneumatic conveying main pipe 11 connected to the end of the fly ash collection pipe 10.

[0031] The conveying fan 12 is installed on the fly ash pneumatic conveying main pipe 11. The fly ash collected in the fly ash pneumatic conveying main pipe 11 flows along the pneumatic conveying main pipe 11 under the action of the conveying fan 12 and is eventually sent back into the furnace.

[0032] Optionally, the vertical angle of the inclined guide plate 2 installed on the lower section of the intermediate furnace wall in the second pass of the boiler is 10°~50°, and the arc-shaped guide plate 3 is part of a circle with a radius of 0.5~1.0 meters. The inclined baffle plate 5 installed on the rear wall of the second pass of the boiler is made of ∠10#~∠20# angle steel or 10#~20# channel steel, and its horizontal angle of installation is 45~65°; a connecting cavity 4 is installed at the upper connection of the inclined baffle plate 5, which forms a common space for the inclined baffle plates 5 from both sides and the ash discharge pipe 6, so that the blocked fly ash falls into the ash discharge pipe 6; the ash discharge pipe 6 can be a round pipe or a square pipe. The transverse baffle plate 7 installed on the rear wall of the second pass of the boiler is made of ∠10#~∠20# angle steel or 10#~20# channel steel.

[0033] Optionally, the horizontal angle of the inclined guide plate 2 is 50°~70°, the length is 400~600mm, and the width is the same as the entire flue. The arc-shaped guide plate 3 is a 1 / 4 arc with a radius of 500mm; the connecting cavity 4 is a square structure with an outer dimension of 300x300mm; the horizontal angle of the inclined baffle plate 5 on the rear furnace wall is 45°~65°, and it is arranged in 2 to 4 groups according to the width of the flue. The diameter of the ash discharge pipe 6 is 100~200mm. The transverse baffle plate 7 on the rear furnace wall is a folded plate, arranged along the entire rear furnace wall, with a horizontal plate width of 300~400mm and a folded plate width of 400mm, arranged along the entire furnace wall, and the folded plate is parallel to the furnace wall behind the ash hopper.

[0034] To address the aforementioned problems, based on the device, another embodiment of the present invention also provides a method for reducing the carbon content of fly ash from biomass boilers, comprising: The flue gas carrying fly ash enters the second pass of the boiler from the boiler body 1. Under the action of the guide plate group consisting of the inclined guide plate 2 and the arc-shaped guide plate 3 installed in the lower section of the intermediate furnace wall of the second pass, the flue gas containing fly ash in the second pass of the boiler is guided to the lower part of the front furnace wall. Under the action of inertial force, some of the fly ash is thrown down to the lower front furnace wall and finally falls into the ash hopper 8 along the furnace wall.

[0035] The fly ash carried in the flue gas is thrown towards the rear furnace wall by the guide plate assembly. The inclined baffle plate 5 installed on the rear furnace wall of the second pass of the boiler blocks the fly ash rising along the rear furnace wall. Since the inclined baffle plate 5 is arranged at an angle, part of the fly ash blocked in the inclined baffle plate 5 falls into the ash discharge pipe 6 under the action of gravity, and then falls into the ash hopper 8 through the ash discharge pipe 6. Another part of the lighter fly ash blocked in the inclined baffle plate 5 is carried by the flue gas and enters the connecting cavity 4 installed on the upper part of the inclined baffle plate, and enters the ash discharge pipe 6, and then falls into the ash hopper 8.

[0036] The transverse baffle plate 7 installed on the rear wall of the boiler's second pass is located below the ash discharge pipe 6. The ash discharge pipe 6 passes through the transverse baffle plate 7. The transverse baffle plate 7 not only blocks the fly ash carried up along the rear wall, but also blocks the fly ash falling along the ash discharge pipe 6, preventing it from being carried away by the flue gas. The ash baffle 9 installed in the ash hopper 8 together with the rear furnace wall forms the ash hopper. The fly ash falling into the ash hopper falls into the fly ash pneumatic conveying main pipe 11 connected to the end of the fly ash collection pipe through multiple fly ash collection pipes 10.

[0037] The conveying fan 12 is installed on the fly ash pneumatic conveying main pipe 11. The fly ash collected in the fly ash pneumatic conveying main pipe 11 flows along the pneumatic conveying main pipe 11 under the action of the conveying fan 12 and is eventually sent back into the furnace (not shown in the figure).

[0038] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this practice should be included within the protection scope of this practice.

Claims

1. A device for reducing the carbon content of fly ash from biomass boilers, characterized in that, It includes an inclined guide plate (2) installed at the lower part of the boiler body (1) in the second pass of the boiler, and an arc-shaped guide plate (3) set at the lower part of the inclined guide plate (2); The boiler body (1) has a rear wall inclined baffle plate (5) and a rear wall transverse baffle plate (7) on the rear wall of the boiler second pass. A connecting cavity (4) is installed on the rear wall inclined baffle plate (5). An ash hopper (8) is provided at the bottom of the boiler body (1). A conveying fan (12) is provided on the ash hopper (8) through the fly ash pneumatic conveying main pipe (11). The fly ash flowing with the flue gas is separated from the flue gas by inertia and gravity under the guidance of the inclined guide plate (2) and the arc-shaped guide plate (3), as well as the blocking effect of the inclined baffle plate (5) and the transverse baffle plate (7) of the rear furnace wall, and falls into the ash hopper (8). Then, the collected fly ash is sent back into the furnace for re-combustion by the conveying fan (12).

2. The device for reducing the carbon content of fly ash from biomass boilers as described in claim 1, characterized in that, The ash hopper (8) is provided with an ash baffle (9), the ash baffle (9) is connected to an ash collection pipe (10), the ash collection pipe (10) is connected to the fly ash pneumatic conveying main pipe (11), and the conveying fan (12) is installed on the fly ash pneumatic conveying main pipe (11).

3. The device for reducing the carbon content of biomass boiler fly ash as described in claim 2, characterized in that, The bottom end of the ash baffle (9) is provided with multiple fly ash collection pipes (10), each fly ash collection pipe (10) is connected to the fly ash pneumatic conveying main pipe (10).

4. The device for reducing the carbon content of fly ash from biomass boilers as described in claim 1, characterized in that, An ash discharge pipe (6) is provided between the connecting cavity (4) and the transverse ash baffle plate (7) of the rear furnace wall.

5. The device for reducing the carbon content of fly ash from biomass boilers as described in claim 1, characterized in that, The lower end of the inclined guide plate (2) is inclined away from the inclined baffle plate (5) of the rear furnace wall.

6. The device for reducing the carbon content of fly ash from biomass boilers as described in claim 1, characterized in that, The arc-shaped opening of the arc-shaped guide plate (3) faces the inclined baffle plate (5) of the furnace wall.

7. A method for reducing the carbon content of fly ash from biomass boilers, characterized in that, The device for reducing the carbon content of biomass boiler fly ash as described in any one of claims 1-6 includes: the fly ash flowing with the flue gas is separated from the flue gas by inertia and gravity under the guiding action of the inclined guide plate (2) and the arc-shaped guide plate (3), and the blocking action of the inclined baffle plate (5) and the transverse baffle plate (7) of the rear furnace wall, and falls into the ash hopper (8) by means of inertia and gravity. Then, the collected fly ash is sent back into the furnace for re-combustion by the conveying fan (12).

8. The method for reducing the carbon content of fly ash from biomass boilers as described in claim 7, characterized in that, The fly ash carried in the flue gas is thrown towards the rear furnace wall by the inclined guide plate (2) and the arc-shaped guide plate (3). The inclined baffle plate (5) of the rear furnace wall blocks the fly ash rising along the rear furnace wall. A part of the fly ash blocked in the inclined baffle plate (5) of the rear furnace wall falls into the ash pipe (6) under the action of gravity, and then falls into the ash hopper (8) through the ash pipe (6). Another part of the lighter fly ash blocked in the inclined baffle plate (5) of the rear furnace wall enters the connecting cavity (4) along the inclined baffle plate (5) of the rear furnace wall under the action of the flue gas, and enters the ash pipe (6), and then falls into the ash hopper (8).

9. A method for reducing the carbon content of fly ash from biomass boilers as described in claim 8, characterized in that, The ash discharge pipe (6) passes through the horizontal baffle plate (7) of the rear furnace wall. The horizontal baffle plate (7) of the rear furnace wall blocks the fly ash carried up along the rear furnace wall and blocks the fly ash falling along the ash discharge pipe (6) to prevent it from being carried by the flue gas again.

10. A method for reducing the carbon content of fly ash from biomass boilers as described in claim 9, characterized in that, The fly ash that falls into the ash hopper (8) passes through multiple fly ash collection pipes (10) and falls into the fly ash pneumatic conveying main pipe (11); the fly ash collected in the fly ash pneumatic conveying main pipe (11) flows along the pneumatic conveying main pipe (11) under the action of the conveying fan (12) and is eventually sent back into the furnace.

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