CN111536507B - Separation and return material regulation and control system and integration method for low-emission circulating fluidized bed boiler - Google Patents

Abstract

A separation and return control system and an integrated method for a low-emission circulating fluidized bed boiler, wherein the separation and return control system comprises a furnace, a separator, a returner, a slag discharge pipe, a slag discharge regulating valve, a slag cooler, an ash discharge pipe, an ash discharge regulating valve, an ash cooler, an ash discharge pipe, an ash discharge regulating valve, an ash cooler and an ash remover; the inlet end of the ash discharge pipe extends into the wind chamber and is connected to the bottom of the return valve, and the movable cylinder is positionally adjustable in the fixed cylinder; the integrated method comprises: first, fuel combustion, flue gas and ash separation under reduced boiler load or reduced fuel calorific value, and second, ash discharge. The present invention achieves adjustable separation ash amount, return ash amount and furnace bed material when the boiler is at low load or when the fuel suddenly changes, by controlling the separation and return ash amount, ash discharge and ash discharge separately, or by jointly controlling the separation and return ash amount and ash discharge as well as the ash discharge and ash discharge, so that the temperature field in the furnace is reasonable and uniform, the boiler can operate safely, stably and efficiently for a long time, and the _NOx and _SO2 pollutants are ultra-lowly discharged.

Description

Low-emission circulating fluidized bed boiler separation return material control system and integration method

Technical Field

The invention relates to a boiler separation and return material control system and an integrated method, and in particular to a low-emission circulating fluidized bed boiler separation and return material control system and an integrated method.

Background Art

Circulating fluidized bed boiler is an environmentally friendly and energy-saving combustion technology. With the application of low-emission circulating fluidized bed boilers with high-efficiency separators and self-balancing returners, the combustion system is optimized, the fluid state is reconstituted, and good low-emission effects of pollutants are achieved. However, fuel replacement and load mutation will affect the safe and stable operation of the boiler, energy-saving combustion and environmentally friendly emissions. Due to the improvement of boiler separation efficiency, the amount of fine ash in the circulating material increases, the bed quality is improved and the bed inventory is reduced, the combustion efficiency is improved, and low-nitrogen combustion is achieved. However, there is a problem of excessive fine ash in the circulating material when the boiler is running at low load or the calorific value of the fuel is reduced, resulting in too low a bed temperature in the lower part of the furnace, unstable combustion and flameout, incomplete combustion of the fuel and reduced desulfurization efficiency in the furnace, which is not conducive to the stable operation of the boiler, efficient combustion and ultra-low emissions of pollutants.

Summary of the invention

The present invention aims to solve the problems of excessive circulating material volume, unstable combustion and flameout, reduced desulfurization efficiency in the furnace, low boiler combustion efficiency and high pollutant emissions in existing low-emission circulating fluidized bed boilers when the load decreases or the calorific value of the fuel decreases, and further provides a low-emission circulating fluidized bed boiler separation and return material control system and an integrated method.

The technical scheme of the present invention is as follows: a separation and return material control system for a low-emission circulating fluidized bed boiler comprises a furnace, a separator and a return material device; the separation and return material control system also comprises a slag discharge pipe, a slag discharge regulating valve, a slag cooler, an ash slag discharge pipe, an ash slag discharge regulating valve, an ash slag cooler, an ash discharge pipe, an ash discharge regulating valve, an ash slag cooler and an ash slag remover;

The vertical material pipe of the return material machine is installed on the upper part of the return material valve of the return material machine, the return material leg of the return material machine is installed on the side of the return material valve, the wind cap of the return material machine is installed on the bottom of the return material valve, the wind chamber of the return material machine is installed on the lower part of the return material valve, the inlet end of the ash discharge pipe extends into the wind chamber and is connected with the bottom of the return material valve, the outlet end of the ash discharge pipe is connected with the ash cooler, the ash discharge regulating valve is installed on the ash discharge pipe, the ash cooler is connected with the ash slag removal machine, the return material leg is connected with the rear lower part of the furnace, a plurality of observation holes are arranged vertically on the vertical material pipe of the return material machine, and a limestone desulfurization interface is provided on the return material leg;

The central cylinder of the separator includes a fixed cylinder and a movable cylinder. The fixed cylinder is installed on the top of the vertical section of the separator. The fixed cylinder is connected to the tail flue. A plurality of groups of through holes are arranged on the wall of the movable cylinder along the length direction. A group of through holes are opened on the wall of the fixed cylinder. The movable cylinder is fixed in the fixed cylinder by a pin passing through a group of through holes and any group of through holes to achieve position adjustment. A plurality of SNCR denitrification interfaces are evenly distributed on the side of the inlet and outlet speed regulating sections. The inlet and outlet speed regulating sections of the separator are installed on the side of the vertical section of the separator. The cone section of the separator is installed at the lower part of the vertical section. The inlet and outlet speed regulating sections are connected to the upper rear outlet of the furnace, and the cone section is connected to the vertical material pipe.

A slag discharge pipe and an ash slag discharge pipe are respectively installed at both ends of the length direction of the bottom of the furnace. The slag discharge regulating valve is installed on the slag discharge pipe, the slag discharge pipe is connected to the slag cooler, and the ash slag discharge regulating valve is installed on the slag discharge pipe, the ash slag discharge pipe is connected to the ash slag cooler, and the slag cooler and the ash slag cooler are respectively connected to the ash removal machine.

The first integrated method of the low-emission circulating fluidized bed boiler separation and return material control system of the present invention comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

Close the ash discharge regulating valve on the ash discharge pipe, and the fuel enters the lower part of the furnace through the feeding device, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section of the separator from the rear outlet of the upper part of the furnace, and then enters the vertical section of the separator around the central tube to separate the flue gas and fine ash;

The length of the movable cylinder of the central cylinder is changed to adjust the separation of flue gas and fine ash, reduce or increase the amount of separated ash, so that the return ash returned to the furnace 1 stabilizes the furnace temperature between 800-900°C, the separated separation ash enters the return feeder through the cone of the separator, and the separation ash enters the return valve through the vertical legs of the return feeder. Part of the return ash returns to the lower part of the furnace through the return legs to heat the fuel entering the bottom of the furnace through the feeding device, and continuously fluidizes and circulates the combustion, and the separated flue gas enters the tail flue through the central cylinder for heat exchange and is discharged out of the furnace;

2. Ash discharge

Close the ash discharge regulating valve on the ash discharge pipe installed at the corresponding return leg position, adjust the opening of the slag discharge regulating valve on the slag discharge pipe, and discharge the large-particle slag formed after the combustion of fuel in the lower part of the furnace. The high-temperature large-particle slag is cooled by the slag cooler and discharged to the ash remover and transported to the slag bin.

The second integrated method of the low-emission circulating fluidized bed boiler separation and return material control system of the present invention comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

Close the ash discharge regulating valve on the ash discharge pipe, and the fuel enters the lower part of the furnace through the feeding device, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section of the separator from the rear outlet of the upper part of the furnace, and then enters the vertical section of the separator around the central tube to separate the flue gas and fine ash;

The separated ash enters the return device through the cone of the separator, and then enters the return valve through the vertical legs of the return device. Part of the return ash returns to the lower part of the furnace through the return legs to heat the fuel entering the bottom of the furnace through the feeding device, and continuously fluidizes and circulates the combustion. The separated flue gas enters the tail flue through the central tube for heat exchange and is then discharged out of the furnace.

2. Ash discharge

Adjust the opening of the slag discharge regulating valve on the slag discharge pipe to remove the large-particle slag formed after the combustion of fuel in the lower part of the furnace, improve the quality of the bed material, and the high-temperature large-particle slag is cooled by the slag cooler and discharged to the ash remover for transportation to the slag bin; adjust the opening of the ash discharge regulating valve on the ash discharge pipe installed at the corresponding return leg position to remove most of the return ash and a small amount of slag, reduce the inventory of bed material, stabilize the temperature in the furnace between 800-900℃, and the high-temperature ash is cooled by the ash cooler and discharged to the ash remover for transportation to the slag bin.

The third integrated method of the low-emission circulating fluidized bed boiler separation and return material control system of the present invention comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

The fuel enters the lower part of the furnace through the feeding device, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace by the flue gas. The flue gas carries fine ash and enters the inlet and outlet speed regulating section of the separator from the rear outlet of the upper part of the furnace. Then, it enters the vertical section of the separator and separates the flue gas and fine ash around the central tube.

The separated ash enters the return device through the cone of the separator, and then enters the return valve through the vertical legs of the return device. Part of the return ash returns to the lower part of the furnace through the return legs to heat the fuel entering the bottom of the furnace through the feeding device, and continuously fluidizes and circulates the combustion. The separated flue gas enters the tail flue through the central tube for heat exchange and is discharged out of the furnace. The opening of the ash discharge regulating valve on the ash discharge pipe is adjusted to discharge part of the return ash, control the amount of return ash returning to the furnace, and stabilize the temperature in the furnace between 800-900℃;

2. Ash discharge

Close the ash and slag regulating valve on the ash and slag discharge pipe installed at the corresponding return leg position, adjust the opening of the ash and slag regulating valve on the ash and slag discharge pipe, and discharge the large-particle slag formed after the combustion of fuel in the lower part of the furnace. The high-temperature large-particle slag is cooled by the slag cooler and discharged to the slag remover, and then transported to the slag bin. The high-temperature ash is cooled by the ash cooler and then discharged to the slag remover, and then transported to the slag bin.

The low-emission circulating fluidized bed boiler separation and return material control system and integrated method 4 of the present invention comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

Close the ash discharge regulating valve on the ash discharge pipe, and the fuel enters the lower part of the furnace through the feeding device, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section of the separator from the rear outlet of the upper part of the furnace, and then enters the vertical section of the separator around the central tube to separate the flue gas and fine ash;

Change the length of the movable cylinder of the central cylinder, adjust the separation of flue gas and fine ash, reduce or increase the amount of separated ash, so that the return ash returned to the furnace stabilizes the furnace temperature between 800-900℃. The separated ash enters the return device through the cone of the separator, and the separated ash enters the return valve through the vertical legs of the return device. Part of the return ash returns to the lower part of the furnace through the return legs to heat the fuel entering the bottom of the furnace through the feeding device, and continuously fluidizes and circulates the combustion. The separated flue gas enters the tail flue through the central cylinder for heat exchange and is discharged out of the furnace.

2. Ash discharge

Adjust the opening of the slag regulating valve on the slag discharge pipe to discharge the large-particle slag formed after the fuel is burned in the lower part of the furnace, so as to improve the quality of the bed material. The high-temperature large-particle slag is cooled by the slag cooler and then discharged to the ash remover and transported to the slag bin;

Adjust the opening of the ash discharge regulating valve installed on the ash discharge pipe at the corresponding return leg position to discharge most of the return ash and a small amount of slag, reduce the inventory of bed material, stabilize the temperature in the furnace between 800-900℃, and the high-temperature ash is cooled by the cold ash machine and discharged to the slag remover and transported to the slag bin.

The fifth integrated method of the low-emission circulating fluidized bed boiler separation and return material control system of the present invention comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

The fuel enters the lower part of the furnace through the feeding device, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace by the flue gas. The flue gas carries fine ash and enters the inlet and outlet speed regulating section of the separator from the rear outlet of the upper part of the furnace. Then, it enters the vertical section of the separator and separates the flue gas and fine ash around the central tube.

The separated ash enters the return device through the cone of the separator, and then enters the return valve through the vertical legs of the return device. Part of the return ash returns to the lower part of the furnace through the return legs to heat the fuel entering the bottom of the furnace through the feeding device, and continuously fluidizes and circulates the combustion. The separated flue gas enters the tail flue through the central tube for heat exchange and is discharged out of the furnace. The opening of the ash discharge regulating valve on the ash discharge pipe is adjusted to discharge part of the return ash, control the amount of return ash returning to the furnace, and stabilize the temperature in the furnace between 800-900℃;

2. Ash discharge

Adjust the opening of the slag regulating valve on the slag discharge pipe to discharge the large-particle slag formed after the fuel is burned in the lower part of the furnace, so as to improve the quality of the bed material. The high-temperature large-particle slag is cooled by the slag cooler and then discharged to the ash remover and transported to the slag bin;

Adjust the opening of the ash discharge regulating valve installed on the ash discharge pipe at the corresponding return leg position to discharge most of the return ash and a small amount of slag, reduce the inventory of bed material, and stabilize the temperature in the furnace between 800-900℃. The high-temperature ash is cooled by the ash cooler and discharged to the ash remover and transported to the slag bin. The high-temperature ash is cooled by the ash cooler and discharged to the ash remover and transported to the slag bin.

In the above scheme, limestone is fed into the limestone desulfurization interface 3-7 on the returner 3 after integration, so as to realize limestone desulfurization in the furnace; and SNCR denitrification interface 2-6 installed on the separator 2 is integrated to realize low-cost SNCR denitrification in the furnace, actively control _NOx generation and _NOx and _SO2 removal in the furnace, and realize ultra-low emission of _NOx and _SO2 pollutants.

Compared with the prior art, the present invention has the following beneficial effects:

1. The adjustable central tube designed in the present invention increases or decreases the total length of the central tube, so that the total length of the central tube can be flexibly adjusted to adjust the efficiency of the separator and control the amount of separated ash, so that the amount of separated ash can be guaranteed when the boiler is under low load or when the fuel changes suddenly, thereby ensuring the stable operation of the boiler.

2. The present invention designs an ash discharge pipe and an ash discharge regulating valve, and controls the amount of ash returned to achieve controllable ash return when the boiler is under low load or when the fuel changes suddenly, so that the temperature in the furnace reaches the design value and can be controlled within the range of 800-900°C, avoiding the occurrence of flameout or shutdown caused by coking due to unstable combustion, environmental emissions not meeting the standards due to low desulfurization efficiency in the furnace, and reduced boiler efficiency due to incomplete combustion of fuel, so that the boiler can operate safely, stably and efficiently for a long time, with ultra-low emissions of _NOx and _SO2 . It has good social and economic benefits.

3. The separation and return material control system of the present invention adopts a high-efficiency separator to achieve adjustable separation efficiency, and at the same time integrates a spare SNCR denitrification interface to achieve coordinated and efficient removal of NO _x after flow state reconstruction.

4. The separation and return material control system of the present invention adopts a non-mechanical self-balancing return material device to achieve a controllable amount of return ash, and at the same time integrates a limestone desulfurization interface to achieve a coordinated and efficient removal of _SO2 after flow state reconstruction.

5. After the separation and return material control system of the present invention realizes flow state reconstruction, the concentration of large particles in the lower part of the furnace is greatly reduced, thereby reducing the wear of the anti-wear layer in the dense phase area in the lower part of the furnace, especially the wear at the junction of the anti-wear layer and the membrane wall, thereby improving the boiler availability and achieving safe operation.

6. By using the separation and return material control system of the present invention, after the fluid state reconstruction is achieved, the material concentration in the secondary air area of the low-emission circulating fluidized bed boiler is reduced during operation, the secondary air penetration disturbance effect is enhanced, the gas-solid mixing effect in the upper part of the furnace is improved, the boiler combustion efficiency is improved, the coal consumption is reduced, and coal-saving combustion is achieved; the lower part of the furnace is more likely to form a reducing atmosphere, inhibit the generation of nitrogen oxides, reduce the generation of thermal NO _X , reduce the original emission of NO _X , achieve low-nitrogen combustion, improve the combustion efficiency of the boiler, and reduce the generation of pollutants. After the fluid state reconstruction is achieved, the power required for material fluidization is reduced, the pressure head of the primary and secondary fans of the boiler is reduced, and the power consumption of the fan is greatly reduced, achieving power-saving operation.

7. The slag discharge pipes are arranged on both sides of the bottom of the furnace. The coarse slag formed after the fuel combustion is discharged through the slag discharge regulating valve. The ash discharge pipe is arranged in the middle of the bottom of the furnace, corresponding to the direction in which the return leg connects to the furnace. The ash discharge regulating valve can be controlled to discharge the return ash and the fine slag formed after the fuel combustion.

8. The integrated method of the present invention, after the fluid state is reconstructed, makes the temperature field in the furnace more reasonable and uniform, and the reaction time of limestone and _SO2 is longer, realizing low Ca/S integrated desulfurization in the furnace, achieving ultra-low pollutant emissions, and increasing the _SO2 removal efficiency to more than 99.8%.

9. The integrated method of the present invention, after fluid state reconstruction, NH ₃ generated by thermal decomposition of urea or ammonia water undergoes SNCR gas phase reaction with NO _X in smoke to remove NO _X in smoke, realize efficient integrated denitrification in the furnace, and achieve ultra-low emission of pollutants.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an overall schematic diagram of a low-emission circulating fluidized bed boiler separation and return material control system and integrated method of the present invention;

FIG2 is a schematic diagram of the planar layout of the interaction between the slag cooler, the ash cooler, the ash cooler and the ash remover;

FIG3 is a schematic diagram of the planar layout of the interaction between the slag cooler, the ash cooler and the ash remover;

FIG4 is a schematic elevational layout diagram of the interaction relationship between the slag cooler, the ash cooler, the ash cooler and the ash remover;

FIG5 is a partial enlarged view of location I of FIG1;

FIG6 is a partial enlarged view of position II of FIG1;

Fig. 7 is a cross-sectional view taken along line K-K of Fig. 1;

FIG8 is a schematic diagram of the overall assembly of a low-emission circulating fluidized bed boiler using the separation and return material control system of the present invention;

FIG9 is a cross-sectional view along the line C-C and the line D-D in FIG8.

DETAILED DESCRIPTION

1 to 5, the low-emission circulating fluidized bed boiler separation and return material control integrated system of the present embodiment includes a furnace 1, a separator 2 and a return material device 3; the separation and return material control system also includes a slag discharge pipe 6, a slag discharge control valve 7, a slag cooler 8, an ash slag discharge pipe 9, an ash slag discharge control valve 10, an ash slag cooler 11, an ash discharge pipe 12, an ash discharge control valve 13, an ash cooler 14 and an ash slag remover 15;

The vertical material pipe 3-1 of the return material returner 3 is installed on the upper part of the return material valve 3-2 of the return material returner 3, the return material leg 3-3 of the return material returner 3 is installed on the side of the return material valve 3-2, the wind cap 3-5 of the return material returner 3 is installed on the bottom of the return material valve 3-2, the wind chamber 3-6 of the return material returner 3 is installed at the lower part of the return material valve 3-2, the inlet end of the ash discharge pipe 12 extends into the wind chamber 3-6 and is connected with the bottom of the return material valve 3-2, the outlet end of the ash discharge pipe 12 is connected with the ash cooler 14, the ash discharge regulating valve 13 is installed on the ash discharge pipe 12, the ash cooler 14 is connected with the ash removal machine 15, the return material leg 3-3 is connected with the rear lower part of the furnace 1, a plurality of observation holes 3-4 are arranged vertically on the vertical material pipe 3-1 of the return material returner 3, and a limestone desulfurization interface 3-7 is provided on the return material leg 3-3;

The central tube 2-1 of the separator 2 includes a fixed tube 2-1-1 and a movable tube 2-1-2. The fixed tube 2-1-1 is installed on the top of the vertical section 2-3 of the separator 2. The fixed tube 2-1-1 is connected to the tail flue 4. A plurality of groups of through holes are arranged on the wall of the movable tube 2-1-2 along the length direction. A group of through holes are opened on the wall of the fixed tube 2-1-1. The movable tube 2-1-2 is fixed in the fixed tube 2-1-1 by a pin passing through a group of through holes and any group of through holes to achieve position adjustment. The length of the central tube 2-1 is variable. A plurality of SNCR denitration interfaces 2-6 are evenly distributed on the side of the inlet and outlet speed regulating sections 2-2. The inlet and outlet speed regulating sections 2-2 of the separator 2 are installed on the side of the vertical section 2-3 of the separator 2. The cone section 2-4 of the separator 2 is installed at the lower part of the vertical section 2-3. The inlet and outlet speed regulating sections 2-2 are connected to the upper rear outlet of the furnace 1, and the cone section 2-4 is connected to the vertical material pipe 3-1.

The bottom of the furnace 1 is respectively provided with a slag discharge pipe 6 and an ash discharge pipe 9 at both ends in the length direction, a slag discharge regulating valve 7 is installed on the slag discharge pipe 6, the slag discharge pipe 6 is connected to a slag cooler 8, an ash discharge regulating valve 10 is installed on the slag discharge pipe 9, the slag discharge pipe 9 is connected to an ash cooler 11, and the slag cooler 8 and the ash cooler 11 are respectively connected to a slag remover 15. The hoods 3-5 may be selected from the prior art patent document: CN205299504U.

As shown in Figure 6, there are three observation holes 3-4, which are arranged vertically in a straight line, and the spacing H1 between two adjacent observation holes is 0.5m. Furthermore, the height H of the return ash in the vertical material pipe 3-1 has a visible range of 2-3m, and when the top of the return ash is located at the lower observation hole 3-4, H is 2m, and when the top of the return ash is located at the upper observation hole 3-4, H is 3m. In this embodiment, the amount of return ash is controlled over a wide range to ensure that the height H of the return ash in the vertical material pipe is ≥ 2.5m, to prevent ash collapse and flue gas backflow and coking, and to control the temperature in the furnace within the range of 800-900℃, which is more suitable for limestone desulfurization in the furnace. The wide range of controllable return ash provides a suitable temperature range, sufficient reaction time, etc., so that the utilization rate of limestone is increased, the desulfurization efficiency in the furnace is improved, and ultra-low emissions of _SO2 pollutants are achieved. This embodiment controls the amount of returned ash in a wide range to ensure the height of the returned ash in the vertical pipe, and controls the temperature in the furnace within the range of 800-900°C. This temperature can reduce the generation of thermal _NOx , achieve low-nitrogen combustion in the furnace, and achieve ultra-low emissions of _NOx pollutants.

Optionally, as shown in FIG1 , the thickness of the concrete layer 2-5 of the inlet and outlet speed regulating sections 2-2 in the height direction is adjustable. The thickness of the concrete layer 2-5 at the inlet and outlet of the inlet and outlet speed regulating sections 2-2 in the height direction increases or decreases at the same time. By changing the inlet and outlet heights of the inlet and outlet speed regulating sections, the flue gas flow velocity is adjusted, the separator efficiency is adjusted, the amount of separated ash is controlled, the furnace bed temperature reaches the design value, the fuel is burned completely, and the boiler is ensured to operate energy-efficiently.

Optionally, as shown in FIG7 , when the thickness of the concrete layer 2-5 at the outlet of the inlet and outlet speed regulating section 2-2 in the width direction changes, the width at the outlet changes in the range of B1-B2. By adjusting the thickness of the concrete layer 2-5 at the outlet of the inlet and outlet speed regulating section 2-2 in the width direction, the angle between the inner side surface at the outlet of the inlet and outlet speed regulating section 2-2 and the horizontal line perpendicular to the axis of the vertical section 2-3 changes in the range of β2-β1, and then the width at the outlet of the inlet and outlet speed regulating section 2-2 changes in the range of B1-B2. By changing the width at the outlet of the inlet and outlet speed regulating section, the flue gas flow velocity is adjusted, the separation efficiency of the separator structure is adjusted, the amount of separated ash is controlled, and the shutdown caused by unstable combustion or coking is avoided to ensure the safe operation of the boiler.

8 and 9 are exemplary diagrams of the present invention applied to a low-emission circulating fluidized bed boiler. The low-emission circulating fluidized bed boiler body, the furnace 1 and the return feeder 3 may adopt those of the prior art patent document CN207146381U.

Through the SNCR denitration interface 2-6 installed on the side of the inlet and outlet speed regulating section 2-2, the reducing agent urea solution or ammonia water containing NH _X is sprayed into the speed regulating section and then thermally decomposed into NH ₃ and smoke dust entering the separator. NH ₃ reacts with NO _X in the smoke dust in the SNCR gas phase, removes NO _X in the smoke dust and generates N ₂ and HO ₂ , realizing denitration in the furnace. The smoke dust entering the separator through the furnace 1 continues to heat and react with the main component of limestone CaCO ₃ to generate CaO and CO _2. The SO ₂ generated by fuel combustion diffuses to the surface and inner pores of CaO. In the presence of oxygen, CaO absorbs SO ₂ in the smoke dust and generates CaSO ₄ , realizing desulfurization in the furnace. By integrating the limestone desulfurization interface 3-7 on the return device 3 and then feeding limestone, limestone desulfurization in the furnace is realized; by integrating the SNCR denitrification interface 2-6 installed on the separator, low-cost SNCR denitrification in the furnace can be realized, and _NOx generation and _NOx and _SO2 removal in the furnace can be actively controlled to achieve ultra-low emissions of _NOx and _SO2 pollutants.

By improving the quality of the boiler bed material, reducing the stock of the bed material, and realizing the reconstruction of the flow state, the temperature field of the furnace is made more reasonable and uniform. The boiler can be operated safely, stably, energy-saving and environmentally friendly for a long time, and the boiler load adjustment range is wide, the fuel adaptability is enhanced, and a separation and return material control system is formed. Utilizing the separation and return material control integrated system of the present invention, when the boiler is running at low load or when the fuel changes suddenly, by controlling the separation ash amount, ash slag and ash discharge separately, or jointly controlling the separation ash amount and ash slag discharge and ash slag and ash discharge, the separation ash amount, the return ash amount and the furnace bed material of the boiler can be adjusted when the load or fuel changes suddenly, so that the temperature field in the furnace is reasonable and uniform, and the stable temperature is controlled within the range of 800-900℃, avoiding the shutdown caused by unstable combustion flameout or coking, the environmental protection emission not meeting the standard caused by the poor low-nitrogen combustion environment and low desulfurization efficiency in the furnace, and the boiler efficiency reduction caused by incomplete combustion of fuel, etc., so that the boiler can be operated safely, stably and efficiently for a long time, with ultra-low emissions of _NOx and _SO2 .

The specific integration method of the control system is as follows:

The first integrated method of the low emission circulating fluidized bed boiler separation return material control system comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

Close the ash discharge regulating valve 13 on the ash discharge pipe 12, and the fuel enters the lower part of the furnace 1 through the feeding device 5, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace 1 by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section 2-2 of the separator 2 from the rear outlet of the upper part of the furnace 1, and then enters the vertical section 2-3 of the separator 2 around the central tube 2-1 to separate the flue gas and fine ash;

The length of the movable cylinder 2-1-2 of the central cylinder 2-1 is changed to adjust the separation of flue gas and fine ash, reduce or increase the amount of separated ash, so that the return ash returned to the furnace 1 stabilizes the temperature in the furnace 1 between 800-900°C, the separated separation ash enters the return device 3 through the cone 2-4 of the separator 2, and the separation ash enters the return valve 3-2 through the vertical leg 3-1 of the return device 3, and part of the return ash returns to the lower part of the furnace 1 through the return leg 3-3 to heat the fuel entering the bottom of the furnace 1 through the feeding device 5, and continuously fluidizes and circulates the combustion, and the separated flue gas enters the tail flue 4 through the central cylinder 2-1 for heat exchange and is discharged out of the furnace;

2. Ash discharge

Close the ash discharge regulating valve 10 on the ash discharge pipe 9 installed at the corresponding return leg 3-3 position, adjust the opening of the slag discharge regulating valve 7 on the slag discharge pipe 6, discharge the large-particle slag formed after the combustion of fuel in the lower part of the furnace 1, and improve the quality of the bed material. The high-temperature large-particle slag is cooled by the slag cooler 8 and discharged to the slag remover 15 and transported to the slag bin.

The boiler load decreases, usually the boiler load is below 50%, to ensure stable combustion and continuous operation under variable working conditions. By changing the length of the central tube 2-1, adjusting the separator efficiency, reducing the amount of separated ash, the return ash returned to the furnace makes the furnace temperature field more reasonable, and stabilizes the temperature in the furnace 1 between 800-900℃; through the SNCR denitration interface 2-6, the reducing agent urea solution or ammonia water containing NH _X is sprayed into the speed regulation section and then thermally decomposed into NH ₃ and smoke entering the separator. NH ₃ reacts with NO _X in the smoke in the SNCR gas phase, removes NO _X in the smoke and generates N ₂ and HO ₂ , realizing denitration in the furnace. The smoke entering the separator through the furnace 1 continues to heat and react CaCO _3, the main component of limestone, to generate CaO and CO _2. SO ₂ generated by fuel combustion diffuses to the surface and inner pores of CaO. In the presence of oxygen, CaO absorbs SO ₂ in the smoke and generates CaSO ₄ , realizing desulfurization in the furnace. By integrating the limestone desulfurization interface 3-7 on the return device 3 and then feeding limestone, limestone desulfurization in the furnace is realized; by integrating the SNCR denitrification interface 2-6 installed on the separator 2, low-cost SNCR denitrification in the furnace can be realized, and _NOx generation and _NOx and _SO2 removal in the furnace can be actively controlled to achieve ultra-low emissions of _NOx and _SO2 pollutants.

The second integrated method of the low-emission circulating fluidized bed boiler separation return material control system comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

Close the ash discharge regulating valve 13 on the ash discharge pipe 12, and the fuel enters the lower part of the furnace 1 through the feeding device 5, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace 1 by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section 2-2 of the separator 2 from the rear outlet of the upper part of the furnace 1, and then enters the vertical section 2-3 of the separator 2 around the central tube 2-1 to separate the flue gas and fine ash;

The separated ash enters the return device 3 through the cone 2-4 of the separator 2, and enters the return valve 3-2 through the vertical leg 3-1 of the return device 3. Part of the return ash returns to the lower part of the furnace 1 through the return leg 3-3, heats the fuel entering the bottom of the furnace 1 through the feeding device 5, and continuously fluidizes and circulates the combustion. The separated flue gas enters the tail flue 4 through the fixed tube 2-1-1 of the central tube 2-1 for heat exchange and is discharged out of the furnace.

2. Ash discharge

Adjust the opening of the slag discharge regulating valve 7 on the slag discharge pipe 6 to discharge the large-particle slag formed after the combustion of the fuel in the lower part of the furnace 1, thereby improving the quality of the bed material. The high-temperature large-particle slag is cooled by the slag cooler 8 and discharged to the ash removal machine 15, and transported to the slag bin; adjust the opening of the ash discharge regulating valve 10 on the ash discharge pipe 9 installed at the corresponding return leg 3-3 position to discharge most of the return ash and a small amount of slag, reduce the inventory of the bed material, stabilize the temperature in the furnace 1 between 800-900℃, and the high-temperature ash is cooled by the ash cooler 11 and discharged to the ash removal machine 15, and transported to the slag bin.

The boiler load decreases, usually the boiler load is below 50%, to ensure stable combustion and continuous operation under variable working conditions. The amount of return ash can be reduced to increase the temperature in the furnace. By adjusting the opening of the ash and slag regulating valve 10, most of the return ash and a small amount of slag returned to the furnace are discharged, reducing the inventory of bed material, making the furnace temperature field more reasonable, and stabilizing the temperature in the furnace 1 between 850-900℃; through the SNCR denitration interface 2-6, the reducing agent urea solution or ammonia water containing NH _X is sprayed into the speed regulation section and then thermally decomposed into NH ₃ and smoke into the separator, and NH ₃ reacts with NO _X in the smoke in the SNCR gas phase, removes NO _X in the smoke and generates N ₂ and HO ₂ , realizing denitration in the furnace. The smoke entering the separator through the furnace 1 continues to heat and react the main component of limestone, CaCO ₃ , to generate CaO and CO _2. The SO ₂ generated by fuel combustion diffuses to the surface and inner pores of CaO. In the presence of oxygen, CaO absorbs SO ₂ in the smoke and generates CaSO ₄ , realizing desulfurization in the furnace. The limestone desulfurization in the furnace is realized by integrating the limestone desulfurization interface 3-7 on the return feeder 3; the SNCR denitrification interface 2-6 installed on the separator 2 can realize low-cost SNCR denitrification in the furnace, actively control the generation of NO _X and the removal of NO _X and SO ₂ in the furnace, and realize ultra-low emissions of NO _X and SO ₂ pollutants.

The third integrated method of the low-emission circulating fluidized bed boiler separation and return material control system comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

The fuel enters the lower part of the furnace 1 through the feeding device 5, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace 1 by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section 2-2 of the separator 2 from the rear outlet of the upper part of the furnace 1, and then enters the vertical section 2-3 of the separator 2 around the central tube 2-1 to separate the flue gas and fine ash;

The separated ash enters the return device 3 through the cone 2-4 of the separator 2, and the separated ash enters the return valve 3-2 through the vertical leg 3-1 of the return device 3. Part of the return ash returns to the lower part of the furnace 1 through the return leg 3-3 to heat the fuel entering the bottom of the furnace 1 through the feeding device 5, and continuously fluidizes and circulates the combustion. The separated flue gas enters the tail flue 4 through the central tube 2-1 for heat exchange and is discharged out of the furnace. The opening of the ash discharge regulating valve 13 on the ash discharge pipe 12 is adjusted to discharge part of the return ash, control the amount of return ash returned to the furnace 1, and stabilize the temperature in the furnace 1 between 800-900℃;

2. Ash discharge

Close the ash discharge regulating valve 10 on the ash discharge pipe 9 installed at the corresponding return leg 3-3 position, adjust the opening of the slag discharge regulating valve 7 on the slag discharge pipe 6, and discharge the large-particle slag formed after the combustion of fuel in the lower part of the furnace 1 to improve the quality of the bed material. The high-temperature large-particle slag is cooled by the slag cooler 8 and discharged to the ash removal machine 15, and transported to the slag bin. The high-temperature ash is cooled by the ash cooler 14 and discharged to the ash removal machine 15, and transported to the slag bin.

The boiler load decreases, usually the boiler load is below 50%. In order to ensure stable combustion and continuous operation under variable conditions, the amount of returned ash is reduced to increase the temperature in the furnace. By adjusting the opening of the ash discharge regulating valve 13, the returned ash in the return valve 3-2 is discharged to reduce the inventory of the bed material, so that the furnace temperature field is more reasonable and the furnace temperature is stabilized between 800-900°C. Through the SNCR denitration interface 2-6, the reducing agent urea solution or ammonia water containing NH _X is sprayed into the speed regulation section and then thermally decomposed into NH ₃ and smoke dust to enter the separator. NH ₃ reacts with NO _X in the smoke dust in the SNCR gas phase, removes NO _X in the smoke dust and generates N ₂ and HO ₂ , thereby realizing denitration in the furnace. The smoke entering the separator through the furnace 1 continues to heat and react the main component of limestone, CaCO ₃ , to generate CaO and CO _2. The SO ₂ generated by fuel combustion diffuses to the surface and inner pores of CaO. In the presence of oxygen, CaO absorbs SO ₂ in the smoke and generates CaSO ₄ , realizing desulfurization in the furnace. The limestone desulfurization in the furnace is realized by integrating the limestone desulfurization interface 3-7 on the return feeder 3; the SNCR denitrification interface 2-6 installed on the separator 2 can realize low-cost SNCR denitrification in the furnace, actively control the generation of NO _X and the removal of NO _X and SO ₂ in the furnace, and realize ultra-low emissions of NO _X and SO ₂ pollutants.

A fourth integrated method for a low-emission circulating fluidized bed boiler separation and return material control system comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

Close the ash discharge regulating valve 13 on the ash discharge pipe 12, and the fuel enters the lower part of the furnace 1 through the feeding device 5, and is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace 1 by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section 2-2 of the separator 2 from the rear outlet of the upper part of the furnace 1, and then enters the vertical section 2-3 of the separator 2 around the central tube 2-1 to separate the flue gas and fine ash;

The length of the movable cylinder 2-1-2 of the central cylinder 2-1 is changed to adjust the separation of flue gas and fine ash, reduce or increase the amount of separated ash, so that the return ash returned to the furnace 1 stabilizes the temperature in the furnace 1 between 800-900°C, the separated separation ash enters the return device 3 through the cone 2-4 of the separator 2, and the separation ash enters the return valve 3-2 through the vertical leg 3-1 of the return device 3, and part of the return ash returns to the lower part of the furnace 1 through the return leg 3-3 to heat the fuel entering the bottom of the furnace 1 through the feeding device 5, and continuously fluidizes and circulates the combustion, and the separated flue gas enters the tail flue 4 through the central cylinder 2-1 for heat exchange and is discharged out of the furnace;

2. Ash discharge

Adjust the opening of the slag discharge regulating valve 7 on the slag discharge pipe 6 to discharge the large-particle slag formed after the fuel is burned in the lower part of the furnace 1, so as to improve the quality of the formed bed material. The high-temperature large-particle slag is cooled by the slag cooler 8 and then discharged to the ash remover 15 and transported to the slag bin;

Adjust the opening of the ash discharge regulating valve 10 installed on the ash discharge pipe 9 installed at the corresponding return leg 3-3 position to discharge most of the return ash and a small amount of slag, reduce the inventory of bed material, stabilize the temperature in the furnace 1 between 800-900℃, and the high-temperature ash is cooled by the cold ash machine 11 and discharged to the ash removal machine 15 and transported to the slag bin.

The boiler load decreases, usually the boiler load is below 50%. In order to ensure stable combustion and continuous operation under variable working conditions, the length of the central tube 2-1 is changed, the separator efficiency is adjusted, the amount of separated ash is reduced or increased, and the return ash returned to the furnace makes the furnace temperature field more reasonable. At the same time, the amount of return ash is reduced to increase the furnace temperature. By adjusting the opening of the ash discharge regulating valve 10, most of the return ash and a small amount of slag returned to the furnace are discharged, the inventory of bed material is reduced, and the furnace temperature field is more reasonable. The length of the central tube 2-1 and the amount of ash discharge are integrated to stabilize the furnace temperature between 850-900℃; the reducing agent urea solution or ammonia water containing _NHX is sprayed into the speed regulating section through the SNCR denitration interface 2-6, and then thermally decomposed into _NH3 and smoke into the separator. _NH3 reacts with _NOX in the smoke in the SNCR gas phase, removes _NOX in the smoke and generates _N2 and _HO2 , so as to realize denitration in the furnace. The smoke entering the separator through the furnace 1 continues to heat and react the main component of limestone, CaCO ₃ , to generate CaO and CO _2. The SO ₂ generated by fuel combustion diffuses to the surface and inner pores of CaO. In the presence of oxygen, CaO absorbs SO ₂ in the smoke and generates CaSO ₄ , realizing desulfurization in the furnace. The limestone desulfurization in the furnace is realized by integrating the limestone desulfurization interface 3-7 on the return feeder 3; the SNCR denitrification interface 2-6 installed on the separator 2 can realize low-cost SNCR denitrification in the furnace, actively control the generation of NO _X and the removal of NO _X and SO ₂ in the furnace, and realize ultra-low emissions of NO _X and SO ₂ pollutants.

A fifth low-emission circulating fluidized bed boiler separation return material control system and integrated method comprises the following steps:

1. Fuel combustion, flue gas and ash separation when boiler load decreases or fuel calorific value decreases

The fuel enters the lower part of the furnace 1 through the feeding device 5, is heated by the fluidized high-temperature bed material and burns rapidly. A large amount of material generated during the combustion process is carried to the upper part of the furnace 1 by the flue gas, and the flue gas carries fine ash into the inlet and outlet speed regulating section 2-2 of the separator 2 from the rear outlet of the upper part of the furnace 1, and then enters the vertical section 2-3 of the separator 2 to separate the flue gas and fine ash around the central tube 2-1; the separated ash enters the return hopper 3 through the cone 2-4 of the separator 2, and the separated ash passes through the return hopper The vertical leg 3-1 of 3 enters the return valve 3-2, and part of the return ash returns to the lower part of the furnace 1 through the return leg 3-3, heats the fuel entering the bottom of the furnace 1 through the feeding device 5, and continuously fluidizes and circulates the combustion. The separated flue gas enters the tail flue 4 through the central tube 2-1 for heat exchange and is discharged out of the furnace. The opening of the ash discharge regulating valve 13 on the ash discharge pipe 12 is adjusted to discharge part of the return ash, control the amount of return ash returned to the furnace 1, and stabilize the temperature in the furnace 1 between 800-900℃;

2. Ash discharge

Adjust the opening of the slag regulating valve 7 on the slag discharge pipe 6 to discharge the large-particle slag formed after the fuel is burned in the lower part of the furnace 1, so as to improve the quality of the formed bed material. The high-temperature large-particle slag is cooled by the slag cooler 8 and then discharged to the ash remover 15 and transported to the slag bin;

Adjust the opening of the ash discharge regulating valve 10 installed on the ash discharge pipe 9 installed at the corresponding return leg 3-3 position to discharge most of the return ash and a small amount of slag, reduce the inventory of bed material, and stabilize the temperature in the furnace 1 between 800-900°C. The high-temperature ash is cooled by the ash cooler 11 and discharged to the ash removal machine 15 and transported to the slag bin. The high-temperature ash is cooled by the ash cooler 14 and discharged to the ash removal machine 15 and transported to the slag bin.

The boiler load decreases, usually the boiler load is below 50%. In order to ensure stable combustion and continuous operation under variable conditions, the amount of returned ash can be reduced to increase the temperature in the furnace. By adjusting the opening of the ash discharge regulating valve 10, most of the return ash and a small amount of slag returned to the furnace are discharged, the inventory of bed material is reduced, and the furnace temperature field is more reasonable. At the same time, the amount of return ash is reduced to increase the furnace temperature. By adjusting the opening of the ash discharge regulating valve 13, the return ash in the return valve 3-2 is discharged to reduce the inventory of bed material, so that the furnace temperature field is more reasonable. By jointly regulating the ash discharge amount and the ash discharge amount integrated measures, the furnace temperature is stabilized between 800-900°C; through the SNCR denitration interface 2-6, a reducing agent urea solution or ammonia water containing _NHX is sprayed into the speed regulation section and then thermally decomposed into _NH3 and smoke dust to enter the separator. _NH3 reacts with _NOX in the smoke dust in the SNCR gas phase to remove _NOX in the smoke dust and generate _N2 and _HO2 , so as to realize denitration in the furnace. The smoke entering the separator through the furnace 1 continues to heat and react the main component of limestone, CaCO ₃ , to generate CaO and CO _2. The SO ₂ generated by fuel combustion diffuses to the surface and inner pores of CaO. In the presence of oxygen, CaO absorbs SO ₂ in the smoke and generates CaSO ₄ , realizing desulfurization in the furnace. The limestone desulfurization in the furnace is realized by integrating the limestone desulfurization interface 3-7 on the return feeder 3; the SNCR denitrification interface 2-6 installed on the separator 2 can realize low-cost SNCR denitrification in the furnace, actively control the generation of NO _X and the removal of NO _X and SO ₂ in the furnace, and realize ultra-low emissions of NO _X and SO ₂ pollutants.

The present invention has been disclosed as above with preferred implementation cases, but it is not intended to limit the present invention. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, makes any simple modifications, equivalent changes and modifications to the above implementation cases based on the technical essence of the present invention, which are still within the scope of the technical solution of the present invention.

Claims (2)

1. The integration method of the low-emission type circulating fluidized bed boiler separation and return regulation system is characterized by comprising the following steps of: it comprises the following steps:

1. Fuel combustion, flue gas and ash separation with reduced boiler load or reduced fuel heating value

The boiler load is below 50%, an ash discharge regulating valve (13) on an ash discharge pipe (12) is closed, fuel enters the lower part of a hearth (1) through a feeding device (5), the fuel is quickly combusted after being heated by fluidized high-temperature bed materials, a large amount of materials generated in the combustion process are carried to the upper part of the hearth (1) by flue gas, the flue gas carries fine ash to enter an inlet and outlet speed regulating section (2-2) of a separator (2) from a rear outlet at the upper part of the hearth (1), the thickness of a concrete layer (2-5) of the inlet and outlet speed regulating section (2-2) in the height direction is adjustable, the thickness of the concrete layer (2-5) of an inlet and outlet of the inlet and outlet speed regulating section (2-2) in the height direction is increased or reduced simultaneously, When the thickness of the concrete layer (2-5) at the outlet of the inlet and outlet speed regulation section (2-2) in the width direction is changed, the width change range of the outlet is B1-B2, the width of the outlet of the inlet and outlet speed regulation section (2-2) is changed, the flow speed of smoke is regulated, the separation efficiency of the separator is regulated, the quantity of separated ash is controlled, then the smoke and fine ash are separated around the central cylinder (2-1) in the vertical section (2-3) of the separator (2), the length of the movable cylinder (2-1-2) of the central cylinder (2-1) is changed, the separation of the smoke and the fine ash is regulated, the quantity of separated ash is reduced or increased, the temperature of returned material ash in the hearth (1) is stabilized between 800 ℃ and 900 ℃, Spraying reducing agent urea solution or ammonia water containing NH _X base into a speed regulation section through an SNCR denitration interface (2-6), thermally decomposing into NH ₃ and smoke dust, entering a separator, carrying out SNCR gas phase reaction on NH ₃ and NO _X in the smoke dust, NO _X in the smoke dust is removed, N ₂ and H ₂ O are generated, denitration in the furnace is realized, limestone is fed after being integrated through a limestone desulfurization interface (3-7) on a material returning device (3), caO and CO ₂ are generated, SO ₂ generated by fuel combustion is diffused to the surface and the inner hole of CaO, under the condition of the participation of oxygen, SO ₂ in smoke dust is absorbed by CaO, caSO ₄ is generated, desulfurization in a furnace is realized, separated ash enters a material returning device (3) through a cone (2-4) of a separator (2), The separated ash enters a return valve (3-2) through a vertical material leg (3-1) of a return device (3), part of the returned ash returns to the lower part of the hearth (1) through the return leg (3-3), the fuel entering the bottom of the hearth (1) through a feeding device (5) is heated, the fuel is continuously fluidized and circularly combusted, and the separated flue gas enters a tail flue (4) through a central cylinder (2-1) for heat exchange and is discharged out of the furnace;

2. Ash and slag discharging

And closing ash and slag discharging regulating valves (10) arranged on ash and slag discharging pipes (9) at the positions of corresponding returning legs (3-3), arranging the ash and slag discharging pipes (6) on two sides of the bottom of the hearth, regulating the opening of the ash and slag discharging regulating valves (7) on the ash and slag discharging pipes (6), discharging large-particle slag formed after the fuel at the lower part of the hearth (1) is combusted, cooling the high-temperature large-particle slag by a slag cooler (8), discharging the cooled high-temperature large-particle slag to an ash and slag removing machine (15), and conveying the cooled high-temperature large-particle slag to a slag bin.

2. The integration method of the low-emission type circulating fluidized bed boiler separation and return regulation system is characterized by comprising the following steps of: it comprises the following steps:

1. Fuel combustion, flue gas and ash separation with reduced boiler load or reduced fuel heating value

The boiler load is below 50%, an ash discharge regulating valve (13) on an ash discharge pipe (12) is closed, fuel enters the lower part of a hearth (1) through a feeding device (5), the fuel is quickly combusted after being heated by fluidized high-temperature bed materials, a large amount of materials generated in the combustion process are carried to the upper part of the hearth (1) by flue gas, the flue gas carries fine ash to enter an inlet and outlet speed regulating section (2-2) of a separator (2) from a rear outlet at the upper part of the hearth (1), the thickness of a concrete layer (2-5) of the inlet and outlet speed regulating section (2-2) in the height direction is adjustable, the thickness of the concrete layer (2-5) of an inlet and outlet of the inlet and outlet speed regulating section (2-2) in the height direction is increased or reduced simultaneously, When the thickness of the concrete layer (2-5) at the outlet of the inlet and outlet speed regulation section (2-2) in the width direction is changed, the width change range of the outlet is B1-B2, the width of the outlet of the inlet and outlet speed regulation section (2-2) is changed, the flow speed of smoke is regulated, the separation efficiency of the separator is regulated, the quantity of separated ash is controlled, then the smoke and fine ash are separated around the central cylinder (2-1) in the vertical section (2-3) of the separator (2), the length of the movable cylinder (2-1-2) of the central cylinder (2-1) is changed, the separation of the smoke and the fine ash is regulated, the quantity of separated ash is reduced or increased, the temperature of returned material ash in the hearth (1) is stabilized between 800 ℃ and 900 ℃, Spraying reducing agent urea solution or ammonia water containing NH _X base into a speed regulation section through an SNCR denitration interface (2-6), thermally decomposing into NH ₃ and smoke dust, entering a separator, carrying out SNCR gas phase reaction on NH ₃ and NO _X in the smoke dust, NO _X in the smoke dust is removed, N ₂ and H ₂ O are generated, denitration in the furnace is realized, limestone is fed after being integrated through a limestone desulfurization interface (3-7) on a material returning device (3), caO and CO ₂ are generated, SO ₂ generated by fuel combustion is diffused to the surface and the inner hole of CaO, under the condition of the participation of oxygen, SO ₂ in smoke dust is absorbed by CaO, caSO ₄ is generated, desulfurization in a furnace is realized, separated ash enters a material returning device (3) through a cone (2-4) of a separator (2), The separated ash enters a return valve (3-2) through a vertical material leg (3-1) of a return device (3), part of the returned ash returns to the lower part of the hearth (1) through the return leg (3-3), the fuel entering the bottom of the hearth (1) through a feeding device (5) is heated, the fuel is continuously fluidized and circularly combusted, and the separated flue gas enters a tail flue (4) through a central cylinder (2-1) for heat exchange and is discharged out of the furnace;

2. Ash and slag discharging

The slag discharging pipes (6) are arranged at two sides of the bottom of the hearth, the opening of a slag discharging adjusting valve (7) on the slag discharging pipes (6) is adjusted, large-particle slag formed after the fuel at the lower part of the hearth (1) is burnt is discharged, and the high-temperature large-particle slag is cooled by a slag cooler (8) and then is discharged to an ash and slag remover (15) and is conveyed to a slag bin; the ash discharging pipe (9) is arranged at the middle position of the bottom of the hearth, the direction of connecting the return leg (3-3) with the hearth (1) is correspondingly regulated, the opening of an ash discharging slag regulating valve (10) arranged on the ash discharging pipe (9) at the position of the corresponding return leg (3-3) is regulated, most of returned ash and a small amount of slag are discharged, the stock of formed bed materials is reduced, the temperature in the hearth (1) is stabilized between 800 ℃ and 900 ℃, and high-temperature ash is cooled by the ash cooling machine (11) and then is discharged to the ash removing machine (15) and is conveyed to the slag bin.