CN211260778U - Sectional combustion system for hearth of circulating fluidized bed boiler - Google Patents

Abstract

The utility model discloses a circulating fluidized bed boiler furnace sectional type combustion system comprises the diaphragm type water-cooled wall, and the below is horizontal grid plate, and the water-cooled wall front wall is dog-ear type feed, broadcasts the material district. Compared with the traditional circulating fluidized bed boiler, after entering a hearth, the fuel firstly undergoes the processes of preheating, evaporation and scattering and then falls into a combustion space above a furnace bottom air distribution plate under the action of gravity to perform fluidized combustion. For the circulating fluidized bed boiler burning biomass fuel or refuse fuel with high moisture content, the system can fully dry, burn and burn off the fuel with high moisture content and difficult ignition, fully spread the agglomerated fuel in the combustion space of the hearth, improve the combustion uniformity and reduce the temperature deviation of the air distribution plate, thereby effectively solving the coking problem of the air distribution plate, improving the combustion efficiency of the boiler and improving the economy. Meanwhile, the system can control the combustion condition in the furnace and the temperature level and the oxygen content of the flue gas by adjusting the air volume at each part, thereby reducing the discharge amount of nitrogen oxides.

Description

Sectional combustion system for hearth of circulating fluidized bed boiler

Technical Field

The utility model relates to a circulating fluidized bed boiler field is a circulating fluidized bed boiler furnace sectional type combustion system particularly, is applied to living beings, garbage power equipment.

Background

With the continuous and rapid development of society, the world demand for energy is continuously increased, and fossil fuels cannot meet the increasing energy demand. And, therefore, the development of renewable energy sources has become a focus of attention all over the world. Wherein, the biomass fuel and garbage fuel power generation technology is applied in a large scale. Because biomass fuel and refuse fuel have characteristics such as moisture height, calorific value are low, the shape is various and not uniform, debris are many, when leading to using these fuels, the phenomenon such as debris agglomeration, air distribution plate coking, slag fall pipe jam, the burning fluctuation is big appears easily in conventional circulating fluidized bed boiler, leads to bed temperature to distribute unevenly, and the fluidization is inhomogeneous, the burning is not abundant, furnace temperature distributes unevenly, and then boiler thermal efficiency reduces, pollutant discharge amount exceeds standard, the condition such as boiler emergency shut down appears even.

The sectional combustion system of the circulating fluidized bed boiler furnace is one of effective ways for solving the problems, is designed aiming at biomass fuels and municipal refuse fuels, is suitable for the characteristics of the fuels, can effectively solve the problem of treatment of agricultural wastes and municipal refuse, and has wide application prospect.

SUMMERY OF THE UTILITY MODEL

In order to overcome the shortcoming such as traditional circulating fluidized bed boiler burn insufficient, easy coking, furnace temperature distribution are inhomogeneous when burning biomass fuel and refuse fuel, the utility model provides a circulating fluidized bed boiler furnace sectional type combustion system can improve combustion efficiency, still can make the air distributor temperature distribution even, can not the coking, and the fluidization is more even.

The utility model adopts the following technical scheme:

a sectional combustion system of a circulating fluidized bed boiler furnace comprises a furnace which is composed of a membrane type water-cooled wall, a combustion area in the furnace is divided into 4 areas, a first area is a preheating and drying material spreading area, is positioned in a fuel inlet area and is positioned on a front wall of the boiler and is a bevel type feeding and material spreading area, a feeding port, a material spreading plate and a secondary primary fluidized air channel are arranged on the water-cooled wall of the first area, material spreading hoods are distributed on the material spreading plate, the feeding port is communicated with the inside of the furnace, the secondary primary fluidized air channel is communicated with the inside of the furnace through the material spreading hoods, fuel enters the furnace from the feeding port, and preheating, drying and spreading are carried out in the area; the second zone is a combustion fluidization zone and is positioned in the lower air distribution plate zone, an air distribution plate is arranged on a water-cooled wall below the second zone, a fluidization air cap is arranged above the air distribution plate, a primary fluidization air channel is arranged below the air distribution plate, and fuel is stably combusted and fluidized in the second zone; the third area is a suspension combustion area and is positioned above the air distribution plate, a lower secondary air pipe and a material return port are arranged on the front water-cooled wall and the rear water-cooled wall of the third area, and fuel entering the boiler is subjected to suspension combustion in the third area; the fourth zone is a burnout zone and is positioned at the uppermost part of a combustion zone in the hearth, an upper secondary air pipe is arranged on the front water-cooling wall and the rear water-cooling wall of the fourth zone, fuel is combusted in the fourth zone, smoke carrying a large amount of heat rises, and heat exchange is carried out between the hearth and working media in the water-cooling walls.

Preferably, the angle formed by the seeding plate and the horizontal direction is inclined downwards to be 15-45 degrees.

Preferably, the seeding blast cap is an inclined blast cap, and the inclined step type seeding blast cap is arranged on a bevel of the preheating and drying seeding area.

The utility model discloses a theory of use is: after the fuel enters the hearth from the feeding port, the small-particle fuel is directly combusted in the third area and then enters the fourth area to be burnt out. The difficult big granule of burning out, irregular fuel and the fuel that the water content is high, at first accomplish preheating in region one, it is dry, the process of scattering, then the fuel passes through region three under the action of gravity and gets into region two, in the in-process that falls, the fuel further experiences preheating, it is dry, the process of scattering, in-process fuel temperature improves, the moisture evaporation water content in the fuel reduces, and fuel homodisperse is in the furnace space, make the fuel that gets into region two easily fully burn, and distribute evenly, then fine ash and the fine particle fuel that the burning produced pass through region three and region four under the effect of stove bottom primary air in proper order, the ash-containing flue gas that the burning produced at last leaves furnace, the fine ash after boiler cyclone separation passes through the feed back mouth and newly gets into region two, so constantly circulate. The hot air required by combustion is fed into the furnace chamber by adopting a sectional and multi-layer air distribution mode, and the primary air is fed into the furnace chamber through the main primary fluidizing air channel and the secondary fluidizing air box and is used as boiler fluidizing air. The secondary air is sent into the hearth through the lower secondary air pipe and the upper secondary air pipe and is used as secondary air of the boiler. The segmented and multilayer air distribution mode can meet the functions of fuel diffusion, combustion product fluidization and timely air quantity adjustment, and is favorable for controlling the combustion and the temperature level in the furnace.

The utility model discloses can be effectively applicable to the circulating fluidized bed boiler who burns biomass fuel or refuse fuel. After adopting above-mentioned technical scheme, need through preheating with traditional circulating fluidized bed boiler fuel, dry, just get into the combustion area behind the process of scattering and burn comparatively, the utility model discloses with the evaporation of water of fuel before the burning, improve fuel temperature, make large granule fuel evenly scatter in furnace combustion space for the fuel burning is abundant, and air distribution plate temperature distribution is even, and the material fluidization is even, avoids large granule fuel to conglomerate and leads to the burning inadequately, effectively solves coking, stifled sediment scheduling problem that causes when burning these fuels, improves boiler efficiency, reduces boiler accident shut-down rate.

The utility model discloses can be through the once amount of wind of adjustment boiler, the amount of secondary wind, the control burning to temperature level and oxygen content suppress nitrogen oxide's production in reasonable scope in the effective control stove, are favorable to reducing the original emission of boiler nitrogen oxide, make the original concentration of discharging of nitrogen oxide at 120mg Nm³The following. Meanwhile, the temperature of the flue gas in the boiler can be controlled to be about 900 ℃, so that the efficiency of the SNCR system can be improved, and the emission of nitrogen oxides in the boiler can be further reduced.

The utility model has the advantages that: one of them, the utility model discloses fuel application scope is extensive, is particularly useful for the biomass fuel and the municipal refuse fuel that moisture is high, the calorific value is low, the shape is various and not of uniform size, debris are many.

Secondly, the fuel is easily ignited and fully combusted through the processes of preheating, drying and scattering, the temperature distribution of the air distribution plate is uniform, the fluidization in the furnace is uniform, the coking and slag blockage are avoided, the combustion efficiency of the boiler is improved, and the economical efficiency is improved.

Thirdly, the utility model discloses a segmentation, multilayer air distribution mode are favorable to fuel to burn out, the combustion products fluidization, and every grade of air distribution homoenergetic is adjusted alone, can improve boiler control ability, guarantees that the burning is stable, improves combustion efficiency.

Fourthly, the utility model discloses can reduce the original emission of boiler nitrogen oxide for the pollutant emission satisfies the national standard requirement.

Drawings

Fig. 1 is a schematic structural view of the present invention;

in figure 1, membrane type water-cooled wall, 2, fluidization hood, 3, spreading hood, 4, feeding port, 5, returning port, 6, main primary fluidization air channel, 7, auxiliary primary fluidization air channel, 8, lower secondary air pipe, 9, upper secondary air pipe, I, preheating, drying and spreading area, II, combustion fluidization area, III, suspension combustion area, IV and burnout area.

Detailed Description

The technical solution of the present invention is further described in detail by the following specific embodiments in combination with the accompanying drawings:

example (b): as shown in the attached figure 1, the sectional combustion system of the circulating fluidized bed boiler hearth comprises a membrane water-cooled wall 1, a horizontal air distribution plate is formed by the membrane water-cooled wall 1 at the lower part of the hearth, a fluidizing air cap 2 is arranged above the horizontal air distribution plate, and a main primary fluidizing air channel 6 is arranged below the horizontal air distribution plate. The area of a feed port 5 in front of the furnace is formed by a membrane wall 1 to form a folded angle type membrane wall, a seeding air cap 3 is arranged above a seeding area below the feed port 4, and an auxiliary primary fluidization air channel 7 is arranged below the seeding area. And a return port 5 is arranged on the rear wall water-cooled wall of the suspension combustion zone III, and the front wall water-cooled wall and the rear wall water-cooled wall are respectively provided with a lower secondary air pipe 8. And the water cooling walls of the front wall and the rear wall of the burnout zone IV are provided with upper secondary air pipes 9. Meanwhile, the water-cooled wall on the inner side of the combustion area is coated with refractory castable to protect the water-cooled wall pipes from being damaged due to abrasion and high temperature.

When the boiler operates, fuel enters a hearth from a feed inlet 4 in front of the boiler, wherein the fuel with smaller particles is directly combusted in the suspension combustion zone III and then is burnt out in a zone IV. Other large-particle fuels are scattered in the preheating and drying seeding region I under the action of the seeding air cap 3, then enter the combustion fluidization region II through the suspension combustion region III under the action of gravity, and are further mixed and diffused under the action of primary air and secondary air, so that the fuels finally combusted in the combustion fluidization region II are uniformly distributed in the combustion space on the air distribution plate. The flue gas and fine ash generated after the part of fuel is combusted fluidize under the action of primary air at the bottom of the furnace, flow upwards, sequentially pass through a combustion fluidization region II, a suspension combustion region III and a burnout region IV to enter a hearth for heat exchange, and then the fine ash separated by a boiler cyclone separator enters the hearth again through a material return port 5, thus the circulation is continuous.

When the boiler operates, primary hot air required by combustion enters a hearth in two ways, one part of the primary hot air enters from a main primary air box 6 at the bottom of the boiler, and the primary hot air is used as main fluidizing air of the boiler through a fluidizing air cap 2, so that materials in the boiler are fluidized. The other part of primary air enters from an auxiliary primary fluidization air channel 7 below the furnace front corner-folded water-cooled wall and is used as boiler seeding air through a seeding air cap 3, so that small-particle fuel is fluidized, and large-particle fuel is diffused into a hearth space. The secondary hot air required by combustion enters from the lower secondary air pipe 8 and the upper secondary air pipe 9 in front of and behind the boiler in two layers and is used as the secondary air of the boiler.

After entering the hearth, the fuel is firstly preheated, evaporated and diffused to be combusted. Because the secondary air and the temperature in the furnace which are sent into the hearth are far higher than the temperature of the fuel entering the furnace, the fuel can be preheated under the action of high temperature, water in the fuel is evaporated, meanwhile, the fuel can be uniformly dispersed in the combustion space of the hearth under the action of air distribution in the falling process, and is uniformly distributed on the air distribution plate at the bottom of the furnace, so that the fuel can be uniformly and fully combusted, the temperature distribution of the air distribution plate is uniform, the fluidization is uniform, and the coking of the air distribution plate due to the nonuniform temperature distribution can not be caused. Meanwhile, the agglomerated fuel is combusted after being scattered, so that the condition of blocking a slag discharge pipe is avoided, the combustion efficiency can be effectively improved, and the economical efficiency of the boiler is improved.

When the boiler operates, the combustion can be accurately adjusted by adjusting the primary air quantity and the secondary air quantity of each level, so that the effect of controlling the combustion condition is achieved, the temperature level in the boiler is uniform and is controlled to be about 900 ℃, the oxygen content is controlled to be in a reasonable range, the discharge amount of nitrogen oxides in the boiler is reduced, and the original discharge concentration of NOx is 120mg/Nm³The following.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the scope of the claims.

Claims (3)

1. A sectional combustion system of a circulating fluidized bed boiler furnace comprises a furnace which is composed of a membrane type water-cooled wall (1), and is characterized in that a combustion area in the furnace is divided into 4 areas, one area is a preheating and drying spreading area (I), the other area is positioned in a fuel inlet area and positioned on a front wall of the boiler and is a bevel type feeding and spreading area, a feeding port (4), a spreading plate and a secondary primary fluidized air channel (7) are arranged on the water-cooled wall of the first area, spreading air caps (3) are distributed on the spreading plate, the feeding port (4) is communicated with the inside of the furnace, the secondary fluidized air channel (7) is communicated with the inside of the furnace through the spreading air caps (3), fuel enters the furnace from the feeding port (4), and preheating, drying and spreading are carried out in the area; the second region is a combustion fluidization region (II) which is positioned in the lower air distribution plate region, an air distribution plate is arranged on the water-cooled wall below the second region, a fluidization air cap (2) is arranged above the air distribution plate, a primary fluidization air channel (6) is arranged below the air distribution plate, and the fuel is stably combusted and fluidized in the second region; the third area is a suspension combustion area (III) and is positioned above the air distribution plate, a lower secondary air pipe (8) and a material return port (5) are arranged on the front water-cooled wall and the rear water-cooled wall of the third area, and fuel entering the boiler is subjected to suspension combustion in the third area; the fourth zone is a burnout zone (IV) which is positioned at the uppermost part of a combustion zone in the hearth, an upper secondary air pipe (9) is arranged on the front water-cooled wall and the rear water-cooled wall of the fourth zone, fuel is combusted in the fourth zone, smoke carrying a large amount of heat rises, and heat exchange is carried out between the hearth and working media in the water-cooled walls.

2. The sectional hearth combustion system of a circulating fluidized bed boiler according to claim 1, wherein an angle formed by the material spreading plate and the horizontal direction is inclined downward at 15-45 °.

3. The sectional furnace combustion system of a circulating fluidized bed boiler according to claim 1, wherein the spreading blast cap (3) is an inclined blast cap, and the inclined blast cap is arranged on a bevel of the preheating and drying spreading area (I) in a step manner.

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