A biomass circulating fluidized bed boiler
By adding primary and secondary air ducts to the biomass circulating fluidized bed boiler and adopting a tapered and expanded structure air supply port design, the low denitrification efficiency and uneven air inlet under low temperature conditions are solved. The problem is that the combustion adequacy and heat uniformity are achieved, the formation of nitrogen oxides and ash slag is reduced, and the safe and efficient operation of the boiler is improved.
Patent Information
- Application Number
- CN202010142078.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2020-03-04
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2040-03-04
AI Technical Summary
The existing biomass circulating fluidized bed boilers have low SNCR denitrification efficiency under low temperature conditions, resulting in large amounts of agents, increased ash slag, and uneven air inlets lead to thermal deviation and fly ash contamination.
Add the primary and secondary air ducts, and through the tapered and expanded structure air supply port design, the uniform air supply into the furnace, control the bed temperature, and reduce the generation of nitrogen oxides and ash accumulation.
The combustion adequacy and heat uniformity are achieved, the nitrogen oxide generation and ash generation are reduced, the fly ash phenomenon is reduced, and the safe and efficient operation of the boiler is improved.
Smart Images
Figure CN111237746B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field related to fluidized bed boilers, and in particular to a biomass circulating fluidized bed boiler. Background Art
[0002] The control of nitrogen oxide emissions from biomass power plants is a strict requirement of the national environmental protection department. At present, most boiler denitrification uses SNCR denitrification. SNCR denitrification is a clean denitrification technology that sprays amino reducing agents into the furnace to reduce and remove NOx in the flue gas to generate nitrogen and water, which is greatly affected by the boiler.
[0003] The current circulating fluidized bed furnace temperature is below 800°C, while the optimal temperature for SNCR denitrification is above 850°C, resulting in low denitrification efficiency, greatly increased reagent usage, boiler wear, and increased ash, which hinders the safe and efficient operation of the boiler.
[0004] At the same time, the existing boilers have the problem of uneven heating of incoming air, which leads to thermal deviation, resulting in insufficient combustion in the furnace and increased ash. At the same time, uneven wind will lead to increased fly ash and pollute the environment. Summary of the invention
[0005] In order to solve the problems existing in the prior art, the present invention provides a biomass circulating fluidized bed boiler, which reduces the generation of nitrogen oxides in biomass combustion by adding primary and secondary air ducts, promotes complete combustion, reduces the accumulation of ash, and prevents the occurrence of fly ash.
[0006] To achieve the above object, the technical solution adopted by the present invention is: a biomass circulating fluidized bed boiler, comprising a furnace with a rectangular cross-section, a water-cooled wall is provided on the outer wall of the furnace, and the water-cooled wall is wrapped on the side wall of the furnace;
[0007] An air supply duct is fixedly installed on the furnace, the air supply duct is communicated with the interior of the furnace, the air supply duct includes a primary air supply duct and a secondary air supply duct, one end of the primary air supply duct is fixedly connected to the bottom of the furnace and communicates with the interior of the furnace, and the other end of the primary air supply duct is fixedly connected to the first fan;
[0008] The secondary air supply duct includes a secondary air mother pipe, a primary air duct with an annular structure and a secondary air duct with an annular structure, the primary air duct and the secondary air duct are both arranged on the side walls of the furnace, the primary air duct is located below the secondary air duct, the primary air duct and the secondary air duct are communicated with each other and both are connected to the secondary air mother pipe, the other end of the secondary air mother pipe is fixedly connected to the second fan, the other end of the primary air duct is communicated with the furnace through a first air supply port, the first air supply port is provided with a plurality of ports and is evenly arranged and fixedly connected to the four side walls of the furnace for air supply, the other end of the secondary air duct is communicated with the furnace through a second air supply port, the second air supply port is provided with a plurality of ports and is evenly arranged and fixedly connected to the four side walls of the furnace for air supply;
[0009] The opening area of the first air supply port close to the furnace is 20-50% smaller than the opening area of the first air supply port away from the furnace. The first air supply port adopts a tapered structure, and an obliquely inserted first air inlet channel is provided between the first air supply port and the boiler side wall.
[0010] The second air supply port adopts a structure that gradually contracts and then expands from away from the furnace to close to the furnace. The opening area of the second air supply port close to the furnace is 20-50% larger than the opening area of the side away from the furnace. An obliquely inserted second air inlet channel is provided on the second air supply port and the side wall of the boiler.
[0011] Preferably, the first air supply port and the first air inlet channel are each provided with four cut-fit connections, and each of the first air supply port and each of the first air inlet channels are arranged in the middle position of the cross section of the furnace side wall.
[0012] In any of the above schemes, preferably, the second air supply port and the second air inlet channel are each provided with four cut-fit connections, and each of the second air supply port and each of the second air inlet channel is arranged in the middle position of the cross-section of the furnace side wall.
[0013] In any of the above solutions, preferably, the first fan and the second fan are fans with adjustable total power.
[0014] In any of the above schemes, preferably, the first fan and the second fan are provided with a pressure control valve and a pressure gauge.
[0015] In any of the above schemes, it is preferred that the secondary air main pipe, the primary air duct and the secondary air duct are all made of metal materials.
[0016] In any of the above schemes, preferably, a bracket is fixedly connected to the side wall of the furnace, and the first fan and the second fan are both installed at one end of the bracket.
[0017] In any of the above schemes, preferably, a plurality of annular heat dissipation pipes are provided on the water-cooled wall, and the heat dissipation pipes are wrapped around the side wall of the furnace to dissipate heat.
[0018] Compared with the prior art, the biomass circulating fluidized bed boiler provided by the present invention has the following beneficial effects:
[0019] 1) The biomass circulating fluidized bed boiler provided by the present invention ensures sufficient combustion by adding a primary air duct and a secondary air duct. The secondary air supply duct is annular and interconnected, and the secondary air sprayed into the boiler from each secondary air nozzle is heated evenly, reducing thermal deviation.
[0020] 2) The present invention provides a biomass circulating fluidized bed boiler, in which the first air supply port is designed with a tapered structure to increase the pressure. After the hot air from the first air supply port is sprayed into the furnace, the temperature rises, the volume expands rapidly, and the air volume and air pressure are large, so that the bed temperature can be controlled to prevent it from being too high, thereby reducing the production of compounds that can be converted into nitrogen oxides.
[0021] 3) The present invention provides a biomass circulating fluidized bed boiler, in which the second air supply port is a gradually contracting and then gradually expanding structure, the wind pressure is relatively small, the air volume is also small, and the volume of hot air entering the furnace body is relatively small, which can not only allow carbon-containing substances and volatiles to be fully retained in the furnace for full combustion, but also reduce the combustible content of fly ash at the boiler outlet. Increasing the wind pressure at the first air supply port is conducive to full contact between the secondary air and the fuel and volatiles. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 A schematic diagram of the overall structure of a biomass circulating fluidized bed boiler provided by the present invention;
[0023] Figure 2 for Figure 1 Top view of the .
[0024] Notes in the figure: 1. Secondary air main pipe; 2. Primary air duct; 3. Secondary air duct; 301. Second air supply port; 4. Furnace. DETAILED DESCRIPTION
[0025] In order to further understand the content of the present invention, the present invention will be described in detail below in conjunction with specific embodiments.
[0026] like Figure 1-Figure 2 As shown, according to an embodiment of a biomass circulating fluidized bed boiler provided by the present invention, it includes a furnace 4 with a rectangular cross-section, a water-cooled wall is provided on the outer wall of the furnace 4, the water-cooled wall is wrapped on the side wall of the furnace 4, a plurality of annular heat dissipation pipes are provided on the water-cooled wall, the heat dissipation pipes are wrapped on the side wall of the furnace 4 for heat dissipation, an air supply duct is fixedly installed on the furnace 4, the air supply duct is communicated with the inside of the furnace 4, and the air supply duct includes a primary air supply duct and a secondary air supply duct.
[0027] In this embodiment, a power supply is also included. The power supply is installed in the power distribution cabinet and is electrically connected to all power-consuming components.
[0028] It should be noted that the furnace 4 is an existing furnace 4 on the market, which is a prior art. A bracket is fixedly connected to the side wall of the furnace 4.
[0029] One end of the primary air supply duct is fixedly connected to the bottom of the furnace 4 and communicates with the interior of the furnace 4, and the other end of the primary air supply duct is fixedly connected to the first fan, which is a fan with adjustable power.
[0030] The secondary air supply duct includes a secondary air main pipe 1, a first-level air duct 2 with an annular structure and a second-level air duct 3 with an annular structure. The first-level air duct 2 and the second-level air duct 3 are both wrapped on the side walls of the furnace 4. The first-level air duct 2 is located below the second-level air duct 3. The first-level air duct 2 and the second-level air duct 3 are interconnected and both are connected to the secondary air main pipe 1. The other end of the secondary air main pipe 1 is fixedly connected to the second fan. The second fan is a fan with adjustable power. The other end of the first-level air duct 2 is connected to the furnace 4 through a first air supply port. The first air supply port is provided with multiple and evenly arrayed fixedly connected to the four side walls of the furnace 4 for air supply. The other end of the secondary air duct 3 is connected to the furnace 4 through a second air supply port 301. The second air supply port 301 is provided with multiple and evenly arrayed fixedly connected to the four side walls of the furnace 4 for air supply.
[0031] In the previous embodiment, the first air supply port and the first air inlet channel are each provided with four cut-fit connections, and each first air supply port and each first air inlet channel are arranged in the middle position of the cross section of the side wall of the furnace 4.
[0032] In the previous embodiment, the second air supply port 301 and the second air inlet channel are each provided with four cut-fit connections, and each second air supply port 301 and each second air inlet channel are arranged in the middle position of the cross section of the side wall of the furnace 4.
[0033] In the previous embodiment, the first fan and the second fan are provided with a pressure control valve and a pressure gauge to monitor and control the pressure in real time. The first fan and the second fan are both installed at one end of the bracket.
[0034] The opening area of the first air supply port close to the furnace 4 is 20-50% smaller than the opening area of the side away from the furnace 4. The first air supply port adopts a tapered structure, and an obliquely inserted first air inlet channel is provided on the first air supply port and the side wall of the boiler. Preferably, the opening area of the side close to the furnace 4 is 35% smaller than the opening area of the side away from the furnace 4, thereby increasing the wind pressure. After the hot air from the first air supply port is sprayed into the furnace 4, the temperature rises, the volume expands sharply, and the air volume and wind pressure are large, thereby controlling the bed temperature so that the bed temperature is not too high, thereby reducing the production of compounds that can be converted into nitrogen oxides, etc.
[0035] The second air supply port 301 adopts a structure that gradually contracts and then expands from away from the furnace 4 to close to the furnace 4, and the opening area of the second air supply port 301 close to the furnace 4 is 20-50% larger than the opening area of the side away from the furnace 4. Preferably, the opening area of the second air supply port 301 close to the furnace 4 is 35% larger than the opening area of the side away from the furnace 4, and an obliquely inserted second air inlet channel is provided on the second air supply port 301 and the side wall of the boiler.
[0036] In the previous embodiment, the secondary air main pipe 1, the primary air duct 2 and the secondary air duct 3 are all made of metal materials.
[0037] The working principle and method of this embodiment:
[0038] Turn on the power, adjust the power of the first fan, control the wind pressure and air volume of the first fan, and provide stable air volume and fluidization pressure for the furnace 4 fuel layer.
[0039] Then the power of the second fan is adjusted to increase or decrease the penetration of the wind in the secondary air mother pipe 1 to achieve a good fluid dynamic field. The second fan conveys the wind to the annular primary air duct 2 through the secondary air mother pipe 1. The primary air duct 2 enters the furnace 4 obliquely through the tapered first air inlet. The wind pressure and air volume of the primary air duct 2 are increased to control the bed temperature so that the bed temperature will not be too high, thereby reducing the production of compounds that can be converted into nitrogen oxides.
[0040] The second fan conveys air to the annular secondary air duct 3 through the secondary air main pipe 1. The secondary air duct 3 enters the furnace 4 obliquely through the second air inlet which first contracts and then expands. The secondary air duct 3 reduces the wind pressure and air volume, which can not only allow the carbon-containing matter and volatile matter to be fully retained in the furnace 4 for full combustion, but also reduce the combustible content of the fly ash at the boiler outlet.
[0041] The structural design of the primary air duct 2 and the secondary air duct 3 can make the fuel fully contact with oxygen in layers during gasification and combustion, but will not cause excessive oxygen.
[0042] Compared with the prior art, this embodiment has the following beneficial effects:
[0043] 1) The biomass circulating fluidized bed boiler provided by the present invention ensures sufficient combustion by adding a primary air duct and a secondary air duct. The secondary air supply duct is annular and interconnected, and the secondary air sprayed into the boiler from each secondary air nozzle is heated evenly, reducing thermal deviation.
[0044] 2) The present invention provides a biomass circulating fluidized bed boiler, in which the first air supply port is designed with a tapered structure to increase the pressure. After the hot air from the first air supply port is sprayed into the furnace, the temperature rises, the volume expands rapidly, and the air volume and air pressure are large, so that the bed temperature can be controlled to prevent it from being too high, thereby reducing the production of compounds that can be converted into nitrogen oxides.
[0045] 3) The present invention provides a biomass circulating fluidized bed boiler, in which the second air supply port is a gradually contracting and then gradually expanding structure, the wind pressure is relatively small, the air volume is also small, and the volume of hot air entering the furnace body is relatively small, which can not only allow carbon-containing substances and volatiles to be fully retained in the furnace for full combustion, but also reduce the combustible content of fly ash at the boiler outlet. Increasing the wind pressure at the first air supply port is conducive to full contact between the secondary air and the fuel and volatiles.
[0046] It is not difficult for those skilled in the art to understand that the present invention includes any combination of the invention content and specific implementation methods of the above specification and the various parts shown in the drawings. Due to the limited space and to make the specification concise, the various schemes composed of these combinations are not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A biomass circulating fluidized bed boiler, comprising a furnace of rectangular cross-section, characterized in that: A water-cooled wall is provided on the outer side wall of the furnace, and the water-cooled wall is wrapped on the side wall of the furnace; An air supply duct is fixedly installed on the furnace, the air supply duct is communicated with the interior of the furnace, the air supply duct includes a primary air supply duct and a secondary air supply duct, one end of the primary air supply duct is fixedly connected to the bottom of the furnace and communicates with the interior of the furnace, and the other end of the primary air supply duct is fixedly connected to the first fan; The secondary air supply duct includes a secondary air mother pipe, a primary air duct with an annular structure and a secondary air duct with an annular structure, the primary air duct and the secondary air duct are both arranged on the side walls of the furnace, the primary air duct is located below the secondary air duct, the primary air duct and the secondary air duct are communicated with each other and both are connected to the secondary air mother pipe, the other end of the secondary air mother pipe is fixedly connected to the second fan, the other end of the primary air duct is communicated with the furnace through a first air supply port, the first air supply port is provided with a plurality of ports and is evenly arranged and fixedly connected to the four side walls of the furnace for air supply, the other end of the secondary air duct is communicated with the furnace through a second air supply port, the second air supply port is provided with a plurality of ports and is evenly arranged and fixedly connected to the four side walls of the furnace for air supply; The opening area of the first air supply port close to the furnace is 20-50% smaller than the opening area of the first air supply port away from the furnace. The first air supply port adopts a tapered structure, and an obliquely inserted first air inlet channel is provided between the first air supply port and the boiler side wall. The second air supply port adopts a structure that gradually contracts and then expands from a position away from the furnace to a position close to the furnace, the opening area of the second air supply port close to the furnace is 20-50% larger than the opening area of the position away from the furnace, and an obliquely inserted second air inlet channel is provided between the second air supply port and the side wall of the boiler; The first air supply port and the first air inlet channel are each provided with four cut-fit connections, and each of the first air supply port and each of the first air inlet channels is provided at the middle position of the cross section of the side wall of the furnace; The water-cooled wall is provided with a plurality of annular heat dissipation pipes, and the heat dissipation pipes are wrapped around the side wall of the furnace to dissipate heat.
2. A biomass circulating fluidized bed boiler according to claim 1, characterized in that: The second air supply port and the second air inlet channel are each provided with four cut-fit connections, and each of the second air supply port and each of the second air inlet channels are arranged at the middle position of the cross section of the side wall of the furnace.
3. The biomass circulating fluidized bed boiler according to claim 1, characterized in that: The first fan and the second fan are fans with adjustable total power.
4. The biomass circulating fluidized bed boiler according to claim 1, characterized in that: The first fan and the second fan are provided with a pressure control valve and a pressure gauge.
5. The biomass circulating fluidized bed boiler according to claim 1, characterized in that: The secondary air main pipe, the primary air duct and the secondary air duct are all made of metal materials.
6. The biomass circulating fluidized bed boiler according to claim 1, characterized in that: A bracket is fixedly connected to the side wall of the furnace, and the first fan and the second fan are both installed at one end of the bracket.