CN113175665B - System and method for low NOx of semicoke and anti-slagging and co-firing - Google Patents

Abstract

The invention discloses a system and method for semi-coke low NO _x anti-slagging mixed combustion, which comprises a biomass bin, a biomass drying device, a biomass mill, an anti-slagging agent preparation barrel, a biomass and an anti-slagging Slagging agent mixing tank, semi-coke bin, semi-coke pulverizer, boiler bottom burner, middle layer burner, reburning burner, overfire air nozzle, panel superheater, convection superheater, economizer, boiler tail Semi-coke-biomass co-combustion system and anti-slagging biomass particle preparation device composed of dust collector, oxygen preheater, etc. The present invention organically combines the semi-coke-biomass blending system with the preparation method of biomass anti-slagging particles, and uses oxygen-enriched combustion technology to improve the ignition and burnout characteristics of semi-coke and reduce the generation of _NOx . It also overcomes the serious slagging problem of biomass, reduces the emission of _CO2 , and makes full use of the waste heat and moisture in the flue gas. The invention is economical and environment-friendly, simple and reliable, has a wide application range and has broad application prospects.

Description

A system and method for semi-coke low NOx anti-slagging mixed combustion

technical field

The invention belongs to the field of clean and high-efficiency utilization of solid carbon-based fuels, and in particular relates to a system and method for blending semi-coke with low NOx _and anti-slagging.

Background technique

As a high-grade clean fuel, semi-coke, a by-product of coal pyrolysis, is burned to generate electricity, which is an important part of realizing clean and efficient cascade utilization of coal. With the rapid development of my country's coal chemical industry, there are a large number of such fuels that need to be burned and utilized urgently. However, the volatile content of semi-coke is very low, and it is very difficult to achieve clean and efficient combustion. Usually, there are problems such as difficulty in ignition and stable combustion, low burnout rate, and high _NOx emissions. Therefore, how to realize the clean and efficient combustion and utilization of such fuels has become a key technical bottleneck restricting the industrial application of clean and efficient cascade utilization of coal in my country, and needs to be resolved urgently. On the other hand, my country's biomass energy is widely distributed, has little pollution, and can effectively mitigate the "greenhouse effect". Serious problems related to ash content such as slagging, deposition and corrosion in the furnace greatly restrict the large-scale utilization of biomass.

Contents of the invention

The purpose of the present invention is to provide a system and method for semi-coke low NO _x slagging-resistant blended combustion, which combines oxygen-enriched combustion technology, with the help of anti-slagging biomass particles, and adopts biomass and semi-coke to be blended in layers in the furnace. Combustion method, and the use of fuel staged and oxygen staged combustion technology, while improving the difficulty of semi-coke ignition, poor burnout and reducing _NOx generation in boilers, it also alleviates the slagging problem caused by high alkali metals in biomass, and fully The waste heat of the flue gas is utilized and water resources are saved.

In order to achieve the above object, the present invention adopts following technical scheme to realize:

A semi-coke low NO _x anti-slagging blended combustion system, including a semi-coke-biomass co-combustion system and an anti-slagging biomass particle preparation device; wherein,

The semi-coke-biomass co-combustion system includes biomass bin, biomass drying device, biomass pulverizer, semi-coke bin, semi-coke pulverizer, boiler bottom burner, middle layer burner, reburning burner, combustion Exhaust nozzles, circulating fans, gas mixers, chemical treatment devices, make-up water pumps, steam turbines and steam pumps, panel superheaters, convective superheaters and economizers arranged in sequence in the flue gas pipeline, and outlets connected to the flue gas pipeline Boiler tail dust collector, oxygen preheater, desulfurization device, flue gas condenser and _CO2 compression device connected in sequence;

The anti-slagging biomass particle preparation device includes an anti-slagging agent preparation tank and a mixing tank of biomass and anti-slagging agent;

The biomass bin is connected to the upper inlet of the biomass drying device through the conveying pipeline, the inlet of the steam pump is connected to the steam extraction pipe of the steam turbine, the outlet of the steam pump is connected to the side inlet of the biomass drying device, and the biomass drying device The outlet is connected to the inlet of the biomass pulverizer, and the outlet of the biomass pulverizer is connected to the fuel nozzle of the bottom burner of the boiler; the semi-coke bin is connected to the inlet of the semi-coke pulverizer through a conveying pipeline, The outlet is connected to the fuel nozzle of the burner in the middle layer of the boiler; the outlet of the anti-slagging agent preparation tank is connected to the inlet of the biomass and anti-slagging agent mixing tank, and the outlet of the biomass and anti-slagging agent mixing tank is connected to the reburning burner Fuel nozzles are connected;

Part of the hot flue gas after the dust collector at the tail of the boiler is connected to the inlet of the circulating fan through the flue gas pipe, and the outlet of the circulating fan is respectively connected to the air inlet nozzle of the reburning burner and the lower inlet of the gas mixer through a three-way valve. The inlet of the boiler is connected to the atmosphere, and the lower outlet is respectively connected to the primary air nozzle of the bottom burner of the boiler and the side inlet of the gas mixer through a three-way valve. The primary and secondary air nozzles and the burn-off air nozzles of the device are connected;

The condensed water outlet of the flue gas condenser is connected to the inlet of the chemical treatment device, and the outlet of the chemical treatment device is connected to the economizer through a feed water pump.

A further improvement of the present invention is that the biomass drying device uses steam from a steam turbine as a drying heat source.

A further improvement of the present invention is that the biomass pulverizer is a fan mill, and the dried biomass particles after grinding are mixed with the anti-slagging agent in the anti-slagging agent preparation tank in the biomass and anti-slagging agent mixing tank, Formation of anti-slagging biomass particles.

The further improvement of the present invention is that the dried biomass particles after the biomass pulverizer is ground and the anti-slagging biomass particles in the biomass and anti-slagging agent mixing tank are used as the pilot fuel and the reburning fuel respectively to burn at the bottom of the boiler The fuel nozzles of the burner and the reburning burner are sprayed into the furnace, and the semi-coke powder ground by the semi-coke pulverizer is sprayed into the furnace from the fuel nozzle of the burner in the middle layer of the boiler, forming a separation of "combustible fuel and difficult-to-combustible fuel". Layer combustion arrangement.

The further improvement of the present invention is that the primary air nozzle of the bottom burner of the boiler injects the oxygen separated by the air separator; The mixture of oxygen and flue gas at the end of the boiler is sprayed into the middle, and the primary and secondary air nozzles of the reburning burner are injected into the flue gas after the dust collector at the end of the boiler.

The further improvement of the present invention is that the condensed water obtained from the flue gas condenser is purified and deoxidized in the chemical treatment device, and then supplied to the economizer as boiler feed water through a feed water pump.

A semi-coke low NO _x slagging-resistant co-firing method, the method is based on the semi-coke low-NO _x slagging-resistant co-firing system, comprising:

The biomass in the biomass bin enters the biomass drying device through the conveying pipeline for drying, and the heat source for drying comes from the partial steam extraction of the steam turbine;

The dried biomass enters the biomass pulverizer for grinding, and the biomass particles after grinding are used as pilot fuel to enter the furnace from the fuel nozzle of the burner at the bottom of the boiler, and part of the oxygen separated by the air separator is burned from the bottom of the boiler The primary air nozzle of the boiler is sprayed into the furnace, and the combination of biomass with low ignition point and high concentration of oxygen promotes the ignition and heat release of the fuel; the secondary air required for combustion is part of the circulating flue gas after the dust collector at the end of the boiler and the air separator The mixture of oxygen obtained by separation; the semi-coke in the semi-coke bin is ground by the semi-coke pulverizer and enters the furnace from the fuel nozzle of the burner in the middle layer of the boiler, and the primary and secondary air required for combustion are circulating hot flue gas Mixed gas with oxygen;

The remaining biomass particles obtained by grinding by the biomass mill enter the mixing tank of biomass and anti-slagging agent to prepare anti-slagging biomass particles, which are used as reburning fuel and enter the furnace from the fuel nozzle of the reburning burner, and burn The required primary and secondary air are part of the circulating hot flue gas after the dust collector at the bottom of the boiler, and the anti-slagging biomass particles are reburned in an oxygen-poor environment, reducing the slagging rate of ash and reducing the formation of NO _x during the combustion process ;

The mixture of circulating hot flue gas at the tail of the boiler and oxygen separated by the air separator is sprayed into the furnace through the burn-off air nozzle, and combined with furnace fuel depth classification, oxygen classification and local oxygen supplementation in the later stage of combustion, the formation of NO _x is further reduced;

The flue gas after complete combustion passes through the panel superheater, convection superheater, economizer, boiler tail dust collector, oxygen preheater, desulfurization device, flue gas condenser and _CO2 compression device in sequence, and finally _CO2 is stored and processed ;

The oxygen separated by the air separator is preheated in the oxygen preheater and then enters the furnace to support combustion, which improves the efficiency of the boiler while utilizing the waste heat of the flue gas;

After the condensed water obtained from the flue gas condenser is purified and deoxidized in the chemical treatment device, it is used as boiler feed water and supplied to the economizer through the feed water pump.

A further improvement of the present invention is to also include:

The high-temperature flue gas heats the working medium water to the state of superheated steam, and sends it into the steam turbine through the main steam pipeline to expand and do work, driving the steam turbine to rotate, and the steam turbine drives the generator to generate electricity.

The further improvement of the present invention is that the anti-slagging agent is a mixture of porous ceramics and dolomite powder, the mass ratio of porous ceramics and dolomite powder is 1:0.1-10, and the particle size of the anti-slagging agent is the particle size of the biomass particle 1/10-1/20, to ensure that the anti-slagging agent and biomass particles can be simultaneously suspended and burned in the boiler furnace.

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

The present invention provides a semi-coke low NO _x slagging-resistant blended combustion system, wherein the semi-coke-biomass co-combustion system adopts a combination of layered blending and oxygen-enriched combustion technology, and utilizes the hot smoke at the tail of the boiler after dust removal Gas and air are separated to produce pure oxygen mixed gas instead of combustion air, and the oxygen concentration can be flexibly adjusted according to the change of the burner area. The traditional air preheater is replaced by an oxygen preheater arranged after the dust collector at the end of the boiler. Make full use of the waste heat of the flue gas; collect and purify the condensed water of the flue gas as boiler feed water, turning waste into treasure; the anti-slagging agent is a mixture of porous ceramics and dolomite powder, the raw material composition is simple, the cost is low, and the biomass is anti-slagging The production process of particles is convenient and fast. It only needs to control the particle size of each component and mix them evenly, so that they can be suspended in the boiler furnace for combustion simultaneously. The anti-slagging agent can not only reduce slagging by increasing the melting point of biomass ash, but also has the effect of desulfurization and adsorption of harmful gases.

The invention provides a low NO _x anti-slagging co-firing method for semi-coke. Combustion method combining "reburning" and "partial oxygen supplementation in the later stage of combustion", injecting part of biomass as pilot fuel into the bottom burner of the furnace, and using pure oxygen as primary air, high oxygen concentration environment and low ignition point characteristics will be Promote the ignition and heat release of biomass, and the corresponding area forms an ignition area or a combustion-supporting area. The temperature in this area is relatively low, and slagging and _NOx generation are less; inject semi-coke into the middle layer burner, and circulate the flue gas The mixed gas with pure oxygen is used as the primary and secondary air of semi-coke, and the corresponding area forms the main combustion zone. During this process, semi-coke can be ignited by making full use of the heat released by biomass combustion, combined with low nitrogen content of biomass and oxygen-rich combustion technology, which can reduce the formation of semi-coke _NOx , and at the same time, there is less biomass and less slagging in this area; the remaining biomass is subjected to anti-slagging treatment, and this part of biomass is injected as reburning fuel through the reburning burner of the boiler In the furnace, the circulating flue gas is used as the primary and secondary air, and the corresponding area forms a reburning zone or a gasification zone. The appropriately lowered regional temperature and the anti-slagging biomass particles jointly slow down the slagging of the biomass, and the biomass particles And the reducing gas generated by biomass gasification will reduce the _NOx generated by the semi-coke in the main combustion zone; the mixture of circulating flue gas and pure oxygen is used as the exhaust air to ensure the combustion efficiency of the fuel; the structure of the oxygen preheater Simple, small in size, and arranged after the dust collector at the end of the boiler, it saves materials compared with the traditional air preheater, and makes full use of the waste heat of the flue gas, which improves the efficiency of the boiler as a whole; the condensed water of the flue gas is chemically purified and deoxidized After treatment, it is used as boiler make-up water, saving water resources.

To sum up, the present invention solves many problems existing in the separate combustion of semi-coke and biomass, realizes full and cascaded utilization of energy, and is not limited by regions and environments. The system is simple, reliable, economical and environmentally friendly, and easy to manage.

Description of drawings

Fig. 1 is the structure schematic diagram of the present invention.

Explanation of reference signs:

1 is the biomass bin, 2 is the biomass drying device, 3 is the biomass pulverizer, 4 is the semi-coke bin, 5 is the semi-coke pulverizer, 6 is the anti-slagging agent preparation barrel, 7 is the biomass and Anti-slagging agent mixing tank, 8 is the air separator, 9 is the gas mixer, 10 is the circulation fan, 11 is the bottom burner of the boiler, 12 is the middle layer burner of the boiler, 13 is the reburning burner, and 14 is the exhaust air Nozzle, 15 is panel superheater, 16 is convective superheater, 17 is economizer, 18 is boiler tail dust collector, 19 is oxygen preheater, 20 is desulfurization device, 21 is flue gas condenser, 22 is CO ₂ is a compression device, 23 is a chemical treatment device, 24 is a feed water pump, 25 is a steam turbine, 26 is a generator, and 27 is a steam pump.

a is air, b is nitrogen, c is oxygen, d is compressed _CO2 storage and disposal, and e is circulating flue gas.

A is the ignition zone or combustion-supporting zone, B is the main combustion zone, C is the reburning zone or gasification zone, and D is the burnout zone.

The solid line is the transportation route of semi-coke, biomass and other solids, the dotted line is the gas (flue gas, steam or oxygen transportation route), and the double-dotted line is the supply water transportation route.

Detailed ways

The present invention will be described in further detail below in conjunction with accompanying drawing

As shown in Figure 1, the present invention provides a semi-coke low NO _x anti-slagging blended combustion system, including a semi-coke-biomass co-combustion system and an anti-slagging biomass particle preparation device.

Among them, the semi-coke-biomass co-combustion system includes biomass bin 1, biomass drying device 2, biomass pulverizer 3, semi-coke bin 4, semi-coke pulverizer 5, boiler bottom burner 11, middle layer Burner 12, reburning burner 13, burn-off air nozzle 14, panel superheater 15, convection superheater 16, economizer 17, boiler tail dust collector 18, oxygen preheater 19, circulation fan 10, gas mixer 9. Steam turbine 25, steam pump 27, overfire air pipeline, hot flue gas pipeline and steam pipeline.

The anti-slagging biomass particle preparation device includes an anti-slagging agent preparation tank 6 and a mixing tank 7 of biomass and anti-slagging agent.

The biomass bin 1 is connected to the upper inlet of the biomass drying device 2 through a conveying pipeline, the inlet of the steam pump 24 is connected to the steam extraction pipeline of the steam turbine 22, and the outlet of the steam pump 27 is connected to the side inlet of the biomass drying device 2. The outlet of the biomass drying device 2 is connected with the inlet of the biomass pulverizer 3, and the outlet of the biomass pulverizer 3 is connected with the fuel nozzle of the bottom burner 11 of the boiler; The inlet of the semi-coke pulverizer 5 is connected, and the outlet of the semi-coke pulverizer 5 is connected with the fuel nozzle of the burner 12 in the middle layer of the boiler. The outlet of the anti-slagging agent preparation barrel 6 is connected to the inlet of the biomass and anti-slagging agent mixing tank 7 , and the outlet of the biomass and anti-slagging agent mixing tank 7 is connected to the fuel nozzle of the reburning burner 13 .

Part of the hot flue gas behind the dust collector 18 at the boiler tail is connected to the inlet of the circulating fan 10 through the flue gas pipe, and the outlet of the circulating fan 10 is respectively connected to the air inlet nozzle of the reburning burner 13 and the lower inlet of the gas mixer 9 through a three-way valve. The inlet of the air separator 8 is connected to the atmosphere, and the lower outlet is respectively connected to the primary air nozzle of the bottom burner 11 of the boiler and the side inlet of the gas mixer 9 through a three-way valve, and the outlet of the gas mixer 9 is connected to the bottom burner of the boiler respectively. The secondary air nozzle of 11, the primary and secondary air nozzles of the intermediate layer burner 12 and the overfired air nozzle 14 are connected.

Panel superheater 15, convective superheater 16 and economizer 17 are sequentially arranged in the flue gas pipeline, boiler tail dust collector 18, oxygen preheater 19, desulfurization device 20, flue gas condenser 21 and _CO2 compression device 22 It is sequentially connected to the outlet of the flue gas pipeline, the outlet of the condensed water of the flue gas condenser 21 is connected to the inlet of the chemical treatment device 23 , and the outlet of the chemical treatment device 23 is connected to the economizer 17 through the feed water pump 24 .

Further, the biomass drying device 2 uses steam from the steam turbine 25 as a drying heat source.

Further, the biomass mill 3 is a fan mill, and the dried biomass particles after grinding and the anti-slagging agent are mixed in the biomass and anti-slagging agent mixing tank 7 to form anti-slagging biomass particles, and the anti-slagging agent The slag agent is a mixture of porous ceramics and dolomite powder, the mass ratio of porous ceramics to dolomite powder is 1:0.1-10, and its particle size is 1/10-1/20 of the biomass particle size to ensure anti-caking The slag agent and biomass particles can be simultaneously suspended and burned in the furnace of the boiler.

Further, the dry biomass particles ground by the biomass pulverizer 3 and the anti-slagging biomass particles in the biomass and anti-slagging agent mixing tank 7 are respectively used as pilot fuel and reburning fuel in the bottom burner 11 of the boiler and the fuel nozzle of the reburning burner 13 are sprayed into the furnace, and the semi-coke powder ground by the semi-coke pulverizer 5 is sprayed into the furnace from the fuel nozzle of the burner 12 in the middle layer of the boiler to form a "combustible fuel package difficult-to-combustible fuel" Layered combustion arrangement.

Further, the primary air nozzle of the bottom burner 11 of the boiler injects the oxygen separated by the air separator 8, the secondary air nozzle of the bottom burner 11, the secondary air nozzle of the middle layer burner 12 and the exhaust air nozzle 14 is sprayed into the mixture of oxygen and boiler tail circulating flue gas, and the primary and secondary air nozzles of the reburning burner 13 are sprayed into the circulating flue gas after the boiler tail dust collector 18.

Furthermore, an oxygen preheater with a simpler structure than the traditional flue gas preheater is installed behind the dust collector 18 at the boiler tail, and the waste heat of dust removal flue gas is used to heat the oxygen entering the furnace, which reduces energy loss and improves boiler efficiency.

Further, after the condensed water obtained from the flue gas condenser 21 is purified and deoxidized in the chemical treatment device 23 , it is supplied to the economizer 17 as boiler feed water through the feed water pump 24 .

The present invention relates to a method for co-firing ultra-low volatile carbon-based fuel and lignite with low _NOx , comprising:

1) The biomass in the biomass bin 1 enters the biomass drying device 2 through the conveying pipeline for drying, and the heat source for drying comes from the partial steam extraction of the steam turbine;

2) The dried biomass enters the biomass pulverizer 3 for grinding, and the part of the biomass particle after grinding is used as a pilot fuel to enter the furnace from the fuel nozzle of the bottom burner 11 of the boiler, and the part separated by the air separator 8 Oxygen is sprayed into the furnace from the primary air nozzle of the burner 11 at the bottom of the boiler, and the combination of biomass with a low ignition point and high-concentration oxygen promotes the ignition and heat release of the fuel; the secondary air required for combustion is part of the circulation after the dust collector 18 at the bottom of the boiler The mixture of flue gas and oxygen separated by the air separator 8; the semi-coke in the semi-coke bin 4 is ground by the semi-coke pulverizer 5 and enters the furnace from the fuel nozzle of the burner 12 in the middle layer of the boiler. The primary and secondary air are a mixture of circulating hot flue gas and oxygen;

3) The remaining biomass particles obtained by grinding the biomass pulverizer 3 enter the biomass and anti-slagging agent mixing tank 7 to prepare anti-slagging biomass particles, which are used as reburning fuel from the reburning burner 13. The nozzle enters the furnace, and the primary and secondary air required for combustion are part of the circulating hot flue gas after the dust collector 18 at the bottom of the boiler. The reburning of anti-slagging biomass particles in an oxygen-poor environment can not only reduce the slagging rate of ash, but also Reduce the formation of SO ₂ and NO _x during combustion;

4) The mixture of circulating hot flue gas at the tail of the boiler and oxygen separated by the air separator 8 is sprayed into the furnace from the overburning air nozzle 14, combined with furnace fuel depth classification, oxygen classification and local oxygen supplementation in the later stage of combustion, further reducing NO _x generation;

5) Flue gas after complete combustion passes through panel superheater 15, convection superheater 16, economizer 17, boiler tail dust collector 18, oxygen preheater 19, desulfurization device 20, flue gas condenser 21 and CO ₂ Compression device 22, finally CO ₂ sequestration treatment;

6) The oxygen separated by the air separator 8 is heated in the oxygen preheater 19 and then enters the furnace to support combustion, and the boiler efficiency is improved while utilizing the waste heat of the flue gas;

7) After the condensed water obtained by the flue gas condenser is purified and deoxidized in the chemical treatment device 23 , it is supplied to the economizer 17 as boiler feed water through the feed water pump 24 .

8) The high-temperature flue gas heats the working medium water to the superheated steam state, and sends it into the steam turbine 25 through the main steam pipeline to expand and perform work, driving the steam turbine to rotate, and the steam turbine drives the generator 26 to generate electricity.

In a nutshell, the present invention utilizes oxygen-enriched combustion technology and anti-slagging biomass particle preparation technology to use dry biomass particles and anti-slagging biomass particles as pilot fuel and reburning fuel respectively and semi-coke to form " The layered blending method of flammable fuel including non-combustible fuel, combined with furnace fuel oxygen depth classification and local oxygen supplement technology in the later stage of combustion, the furnace is divided into ignition/combustion zone, main combustion zone, reburning/gasification zone from bottom to top and burnout zone four combustion zones. The system design not only solves the problems of difficult ignition and burnout of semi-coke and large amount _{of NOx} , but also overcomes the serious slagging problem caused by high alkali metal content in biomass, and at the same time reduces the CO ₂ emission of coal-fired boilers. The invention makes full use of energy of different grades, has wide adaptability, is economical and environment-friendly, and is convenient for management.

It should be understood that this embodiment is only used to illustrate the present invention and is not intended to limit the scope of the present invention. In addition, it should also be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, however, these equivalent forms also fall within the limits of the appended claims of the present application range.

Claims (3)

1. A semi-coke low NO _x anti-slagging blended combustion system is characterized in that it includes a semi-coke-biomass co-combustion system and an anti-slagging biomass particle preparation device; wherein, The semi-coke-biomass co-combustion system includes a biomass bin (1), a biomass drying device (2), a biomass mill (3), a semi-coke bin (4), a semi-coke pulverizer (5), Boiler bottom burner (11), boiler middle layer burner (12), reburning burner (13), burn-off air nozzle (14), circulation fan (10), gas mixer (9), chemical treatment device (23 ), make-up water pump (24), steam turbine (25) and steam pump (27), panel superheater (15), convective superheater (16) and economizer (17) arranged in the flue gas pipeline in sequence, and Boiler tail dust collector (18), oxygen preheater (19), desulfurization device (20), flue gas condenser (21) and _CO2 compression device (22) connected in sequence with the outlet of the flue gas pipeline; The anti-slagging biomass particle preparation device includes an anti-slagging agent preparation tank (6) and a mixing tank (7) of biomass and anti-slagging agent; The biomass bin (1) is connected to the upper inlet of the biomass drying device (2) through a conveying pipeline, the inlet of the steam pump (27) is connected to the steam extraction pipeline of the steam turbine (25), and the outlet of the steam pump (27) is connected to the biomass The side inlet of the material drying device (2) is connected, the outlet of the biomass drying device (2) is connected with the inlet of the biomass pulverizer (3), the outlet of the biomass pulverizer (3) is connected with the bottom burner of the boiler (11) is connected to the fuel nozzle; the semi-coke bin (4) is connected to the inlet of the semi-coke pulverizer (5) through the conveying pipeline, and the outlet of the semi-coke pulverizer (5) is connected to the burner (12) in the middle layer of the boiler The fuel nozzles are connected; the outlet of the anti-slagging agent preparation tank (6) is connected to the inlet of the biomass and anti-slagging agent mixing tank (7), and the outlet of the biomass and anti-slagging agent mixing tank (7) is connected to the reburning burner (13) connected to the fuel nozzle; Part of the hot flue gas behind the dust collector (18) at the boiler tail is connected to the inlet of the circulating fan (10) through the flue gas pipe, and the outlet of the circulating fan (10) is respectively connected to the air inlet nozzle of the reburning burner (13) through a three-way valve. It is connected to the lower inlet of the gas mixer (9), the inlet of the air separator (8) is connected to the atmosphere, and the lower outlet is respectively connected to the primary air nozzle of the boiler bottom burner (11) and the gas mixer (9) through a three-way valve. The side inlet is connected, and the outlet of the gas mixer (9) is respectively connected to the secondary air nozzle of the boiler bottom burner (11), the primary and secondary air nozzles of the boiler middle layer burner (12), and the overfired air nozzle (14) connected; The condensed water outlet of the flue gas condenser (21) is connected to the inlet of the chemical treatment device (23), and the outlet of the chemical treatment device (23) is connected to the economizer (17) through the feed water pump (24); The biomass mill (3) is a fan mill, and the dried biomass particles after grinding and the anti-slagging agent in the anti-slagging agent preparation barrel (6) are placed in the biomass and anti-slagging agent mixing tank (7) Mixed to form anti-slagging biomass particles, the dried biomass particles after grinding by the biomass mill (3) and the anti-slagging biomass particles in the biomass and anti-slagging agent mixing tank (7) are respectively used as primers Burning fuel and reburning fuel are sprayed into the furnace through the fuel nozzles of the boiler bottom burner (11) and the reburning burner (13), and the semi-coke powder ground by the semi-coke pulverizer (5) is discharged from the middle layer burner (12) of the boiler. ) fuel nozzles are sprayed into the furnace, forming a layered combustion arrangement of "combustible fuel packaged with difficult-to-combustible fuel"; The biomass drying device (2) uses steam from the steam turbine (25) as a drying heat source; The primary air nozzle of the boiler bottom burner (11) injects the oxygen separated by the air separator (8), the secondary air nozzle of the boiler bottom burner (11), the primary and secondary air of the boiler middle burner (12) The air nozzle and the burn-off air nozzle (14) are sprayed with a mixture of oxygen and boiler tail circulating flue gas, and the primary and secondary air nozzles of the reburning burner (13) are sprayed into the circulating flue gas after the boiler tail dust collector (18) ; The condensed water obtained from the flue gas condenser (21) is purified and deoxidized in the chemical treatment device (23), and then used as boiler feed water to supply the economizer (17) through the feed water pump (24); The anti-slagging agent is a mixture of porous ceramics and dolomite powder, the mass ratio of porous ceramics to dolomite powder is 1:0.1-10, and the particle size of the anti-slagging agent is 1/10-1/20 of the biomass particle size , to ensure that the anti-slagging agent and biomass particles can be simultaneously suspended and burned in the boiler furnace. 2. A method for semi-coke low NO _x anti-slagging blended combustion, characterized in that the method is based on a system of semi-coke low NO _x anti-slagging blended combustion according to claim 1, comprising: The biomass in the biomass bin (1) enters the biomass drying device (2) through the conveying pipeline for drying, and the heat source for drying comes from the partial steam extraction of the steam turbine; The dried biomass enters the biomass pulverizer (3) for grinding, and the part of the ground biomass particles enters the furnace from the fuel nozzle of the bottom burner (11) of the boiler as the pilot fuel, and passes through the air separator (8) Part of the separated oxygen is sprayed into the furnace from the primary air nozzle of the burner (11) at the bottom of the boiler, and the combination of biomass with a low ignition point and high-concentration oxygen promotes the ignition and heat release of the fuel; the secondary air required for combustion removes dust from the tail of the boiler The mixture of part of the circulating flue gas after the separator (18) and the oxygen separated by the air separator (8); The fuel nozzle of the middle layer burner (12) enters the furnace, and the primary and secondary air required for combustion is a mixture of circulating hot flue gas and oxygen; The remaining biomass particles obtained by grinding the biomass mill (3) enter the biomass and anti-slagging agent mixing tank (7) to prepare anti-slagging biomass particles, which are used as reburning fuel from the reburning burner ( 13) The fuel nozzle enters the furnace, and the primary and secondary air required for combustion are part of the circulating hot flue gas after the dust collector (18) at the bottom of the boiler. slag rate, and reduce the formation of NO _x in the combustion process; The mixture of circulating hot flue gas at the tail of the boiler and oxygen separated by the air separator (8) is sprayed into the furnace from the overburning air nozzle (14), combined with furnace fuel depth classification, oxygen classification and local oxygen supplementation in the later stage of combustion, further reducing the _NOx generation; The flue gas after complete combustion passes through the panel superheater (15), convection superheater (16), economizer (17), boiler tail dust collector (18), oxygen preheater (19), desulfurization device (20 ), the flue gas condenser (21) and the CO ₂ compression device (22), and finally the CO ₂ is stored and processed; The oxygen separated by the air separator (8) is preheated in the oxygen preheater (19) and enters the furnace for combustion support, which improves the efficiency of the boiler while utilizing the waste heat of the flue gas; The condensed water obtained from the flue gas condenser is purified and deoxidized in the chemical treatment device (23), and is used as boiler feed water to be supplied to the economizer (17) through the feed water pump (24). 3. a kind of semi-coke low NO according to claim ₂ The method for anti-slagging blending, is characterized in that, also comprises: The high-temperature flue gas heats the working medium water to the state of superheated steam, and sends it into the steam turbine (25) through the main steam pipeline to expand and perform work, driving the steam turbine (25) to rotate, and the steam turbine (25) drives the generator (26) to generate electricity.

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