Device and method for independently combusting biomass and cooperatively mixing coal-fired power plant boiler

Abstract

The invention discloses a device and a method for independently combusting biomass and cooperatively mixing a coal-fired power plant boiler. The device comprises high-temperature flue gas generated after low-nitrogen combustion of one or more fixed bed, moving bed or fluidized bed combustion boilers or a front independent biomass combustion boiler formed by the fixed bed, moving bed or fluidized bed combustion boilers; the flue gas is fed into the lower part, the middle part and the upper part of a hearth of the main coal-fired power plant boiler according to a set mixing ratio through a high-temperature flue gas pipeline, is coated with a flue at each stage of heating surface and a mixing port of a tail circulating flue, is mixed with main stream flue gas generated after combustion of the main coal-fired power plant boiler, enters an SCR (Selective Catalytic Reduction) together, and is discharged into the atmosphere after being subjected to flue gas denitration and subsequent purification treatment. According to the invention, high-temperature flue gas, dynamic intelligent regulation and control and heat gradient utilization after grading mixing and independent combustion of biomass under various loads of the main coal-fired power plant boiler can be realized; according to the invention, a coal-fired system can be thoroughly split under low load, 100% independent low-nitrogen combustion biomass multi-stage mixing is realized, and low-carbonization and zero-carbonization long-period safe operation of a main coal-fired power plant boiler is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of coal-fired power station boilers, and in particular relates to a device and method for independently burning biomass and co-blending coal-fired power station boilers. Background Art

[0002] The technology of mixing biomass with coal-fired boilers is an important means to alleviate carbon emission pressure and promote energy structure transformation, and has received widespread attention at home and abroad. There are three main ways to couple coal-fired boilers with biomass power generation, namely direct coupling, indirect coupling and parallel coupling. Direct coupling is to grind biomass particles into powder and then pass it into the combustion zone of a coal-fired boiler for blending. The transformation difficulty of this scheme is relatively low, but there are problems such as high cost of biomass raw material pretreatment, stickiness of biomass powder that easily causes pipeline blockage, and aggravates boiler corrosion and slagging, and catalyst poisoning of denitrification device; indirect coupling is to produce combustible gas through gasification or pyrolysis of biomass, and then directly send the combustible gas into the coal-fired boiler or use a special burner. This scheme alleviates the problems of slagging and corrosion in direct coupling, but there are defects such as high system complexity, large initial investment, poor fuel adaptability and unfavorable large-scale biomass blending. Therefore, most indirect coupling biomass blending ratios are within 10%; parallel coupling is to build an independent biomass combustion boiler near the existing coal-fired boiler, and the steam generated and the steam generated by the coal-fired boiler enter the turbine together to complete power generation. The advantage of this scheme is that it can achieve 100% coupling of biomass and will not affect the original coal-fired boiler, but this technical scheme has the highest investment cost and requires the addition of a complete biomass boiler, pipeline system and exhaust gas treatment system. In addition, the parameters of the biomass thermal system used for coupling are lower than those of the coal-fired boiler, resulting in its power generation efficiency being lower than that of indirect coupling power generation.

[0003] Europe began the research and practice of coal-fired boiler coupled biomass power generation in the 1990s. Most European countries adopt the direct coupling method because of the advantages of low transformation and maintenance costs and simple system. my country began the practice of coal-fired boiler coupled biomass power generation in 2004, mainly using direct coupling and indirect coupling. However, due to factors such as changes in national policies and rising biomass prices, most coal-fired boiler coupled biomass power generation projects are in a state of suspension or loss. In summary, the existing coal-fired boiler coupled biomass power generation technologies are not suitable for the current major demand for low-carbon transformation of coal-fired power generation. Therefore, it is necessary to develop a new type of coal-fired boiler coupled biomass power generation technology solution to solve the problems of severe corrosion and slagging, high difficulty in transformation, and low blending ratio in the existing biomass blending scheme. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a technical device and method for independently burning biomass and synergizing coal-fired power station boilers. A series of independent or combined biomass direct combustion and biomass sulfurization combustion equipment are installed near the main coal-fired power station boiler of the coal-fired generator set. All of these independent or combined equipment can generate high-temperature flue gas after combustion. The generated high-temperature flue gas is distributed along the mixing ports at different positions according to the proportion requirements and sent to the main coal-fired power station boiler furnace, heating surfaces at all levels and tail flue. After mixing with the flue gas in the main coal-fired power station boiler furnace, it is sent to the SCR reactor together to implement denitration reaction, and then dust and desulfurization are successively discharged through the chimney. The present invention can achieve 100% biomass blending, and effectively solves the problems of large carbon emissions of coal-fired power station boilers, difficulty in long-term low-load safe operation, and low temperature before the flue gas is sent to the SCR reactor.

[0005] In order to achieve the above-mentioned objectives, in the first aspect, the present invention provides a method for independently burning biomass and synergistically blending a coal-fired power station boiler, wherein the flue gas generated by the independent combustion of biomass is sent into the mixing ports of the lower, middle and upper regions of the furnace of the main coal-fired power station boiler and the subsequent stages of heating surfaces covered with the flue and the tail flow flue through a high-temperature flue gas duct according to a set blending ratio, and is mixed with the mainstream flue gas after combustion in the main coal-fired power station boiler and enters the SCR together to complete flue gas denitrification and subsequent purification treatment before being discharged into the atmosphere, and the mixing ports are opened in the lower, middle and upper regions of the furnace of the main coal-fired power station boiler and the membrane water-cooled wall pipe-type furnace wall covering the various stages of heating surfaces downstream of the furnace and the steel furnace wall of the tail flow flue.

[0006] Furthermore, air becomes high-temperature air after heat exchange with high-temperature flue gas, and the high-temperature air is used to guide the flue gas generated by the independent combustion of biomass; or the pressurized flue gas generated by the independent combustion of biomass is directly sent to the mixing port; or the flue gas generated by the independent combustion of biomass is pressurized and sent to the mixing port to overcome the system flow resistance of the high-temperature flue gas mixed with the main coal-fired power station boiler.

[0007] Furthermore, the biomass is pyrolyzed in advance, and the high-temperature flue gas produced after direct combustion of the pyrolysis gas is sent to the flue gas mixing ports of various levels of the main coal-fired power station boiler through the high-temperature flue gas pipeline; the biomass is gasified in advance, and the high-temperature flue gas produced after direct combustion of the gasification gas is sent to the flue gas mixing ports of various levels of the coal-fired power station boiler through the high-temperature flue gas pipeline.

[0008] Furthermore, the supplied biomass raw materials are sorted according to their particle sizes, and fixed-bed layered combustion boilers, moving bed layered combustion boilers or normal-pressure fluidized bed combustion boilers or pyrolysis furnaces or gasification furnaces are selected respectively, and the larger biomass raw materials are sent to the moving bed layered combustion boiler for combustion; the smaller biomass raw materials are sent to the fixed bed layered combustion boiler or normal-pressure fluidized bed combustion boiler for combustion; when there is domestic sludge to be treated at the location of the main coal-fired power station boiler, the sludge with a moisture content of 35% to 40% after drying by other thermal energy is directly sent to the normal-pressure fluidized bed combustion boiler for direct combustion, and the high-temperature flue gas generated by it is sent to the mixing port of the main coal-fired power station boiler.

[0009] Furthermore, the high-temperature flue gas generated after the independent combustion of biomass is sent to the high-temperature flue gas pipeline for transportation to the main coal-fired power plant boiler for mixing after the primary flue gas purification of gas-solid separation, or flocculants are sprayed into the flue gas after combustion before separation to promote the coagulation of fly ash and aerosol particles into large particles for removal.

[0010] In the second aspect, the present invention also provides a device for independently burning biomass and blending coal-fired power station boilers, including a front biomass independent combustion boiler and a main coal-fired power station boiler, the main coal-fired power station boiler has mixing ports in the lower, middle, and upper areas of the furnace and the flue covered with heating surfaces at all levels downstream of the furnace and the tail flow flue, the flue gas outlet of the biomass independent combustion boiler is connected to the mixing port, and a high-temperature flue gas regulating baffle with adjustable opening is arranged on the flue gas pipeline connecting the flue gas outlet of the biomass independent combustion boiler to the mixing port; the front biomass independent combustion boiler adopts one of the following boiler systems: ① one or more fixed-bed layered combustion boilers that independently burn biomass A, ② one or more independent moving bed layered combustion boilers B for burning biomass, ③ one or more independent atmospheric fluidized bed combustion boilers C for burning biomass, ④ one or more fixed bed layered combustion boilers A and a combined boiler system of moving bed layered combustion boiler B and atmospheric fluidized bed combustion boiler C, ⑤ one or more pressurized circulating fluidized bed boilers, ⑥ one or more moving bed layered combustion boilers B or atmospheric fluidized bed combustion boilers C, combined with one or more biomass pyrolysis furnaces or biomass gasification furnaces; the aforementioned pre-biomass independent combustion boilers are all low-nitrogen combustion biomass independent combustion boilers based on air staging, fuel staging and flue gas recirculation coupling.

[0011] Furthermore, all the air required for combustion in the pre-biomass independent combustion boiler comes from the secondary hot air at the outlet of the air preheater at the rear of the main coal-fired boiler. An air preheating interlayer is provided in the furnace wall of the pre-biomass independent combustion boiler. The cold air is preheated by the inner supporting steel plate in the air preheating interlayer and then sent into or sucked into the blower inlet and mixed with the cold air at the blower inlet to increase the inlet temperature of the cold end of the air preheater, which is used to increase the metal wall temperature of the cold end of the air preheater to inhibit the low-temperature corrosion of the air preheater, and at the same time assist the long-term safe operation of the pre-biomass independent combustion boiler and the main coal-fired power station boiler in air synergistic mixing. The furnace wall structure of the pre-biomass independent combustion boiler is set to six layers, from the inside of the high-temperature flue gas to the air side outside the furnace wall, respectively: refractory material, heat insulation material layer, inner supporting steel plate, air preheating interlayer, outer supporting steel plate, and insulation layer, wherein the inner supporting steel plate is welded with grabbing nails for fixing the refractory material. The grate in the fixed bed layered combustion boiler described in the pre-biomass independent combustion boiler is a fixed grate or a fixed bed rotating grate; the grate in the moving bed layered combustion boiler is a chain moving grate, a reciprocating moving grate or a water-cooled vibrating grate; the atmospheric pressure fluidized bed combustion boiler adopts a boiling fluidized bed combustion boiler, an internal circulation fluidized bed combustion boiler or an external circulation fluidized bed combustion boiler.

[0012] Furthermore, a high-temperature and high-pressure induced draft fan is arranged on the flue gas pipeline from the flue gas outlet of the front biomass independent combustion boiler to the mixing port of the main coal-fired power station boiler to overcome the system flow resistance of the high-temperature flue gas mixing with the main coal-fired power station boiler.

[0013] Furthermore, the flue gas outlet of at least one pre-biomass combustion boiler is connected to the flue gas inlet of the high-temperature tubular air preheater, the flue gas outlet of the high-temperature tubular air preheater is connected to the horizontal pipe in front of the SCR reactor inlet of the main coal-fired power station boiler, the high-temperature air outlet of the high-temperature tubular air preheater is provided with a high-temperature air outlet header, the high-temperature air outlet header is connected to the high-temperature air ejector, and the air inlet of the high-temperature tubular air preheater is connected to the air preheater; the high-temperature air ejector, a flocculant injection device is provided in front of the horizontal cyclone separator, the particle outlet of the horizontal cyclone separator is connected to the furnace through the material leg, and the flue gas outlet of the horizontal cyclone separator is connected to the flue gas inlet of the high-temperature tubular air preheater; or the fixed bed layered combustion boiler A or the moving bed layered combustion boiler The horizontal cyclone separator at the flue gas outlet of the furnace B is replaced by 1 to n inwardly extending rotating bosses. The high-temperature flue gas generated from the fixed-bed layered combustion boiler A or the moving-bed layered combustion boiler B passes through 1 to n rotating bosses and merges into the total high-temperature flue gas duct, and is connected to the mixing port on the main coal-fired power station boiler; the furnace flue gas outlet of the fluidized bed combustion boiler C is connected to the cyclone separator, and a flocculant injection device is arranged in front of the flue gas inlet of the cyclone separator. The flue gas outlet of the cyclone separator is connected to the mixing port on the main coal-fired power station boiler through a high-temperature flue gas duct, and the high-temperature flue gas duct is connected to a high-temperature air ejector, and the high-temperature air ejector is connected to a high-temperature air outlet header; the particle outlet of the cyclone separator is connected to a return device through a riser, and the return device is connected to the furnace.

[0014] Furthermore, an equalizing flow distributor is arranged above the furnace of the main coal-fired power station boiler and in the flue gas duct in front of the SCR reactor inlet, or the equalizing flow distributor is only arranged in the flue gas duct in front of the SCR reactor inlet; the cross-section of the equalizing flow distributor is rhombus, rectangle or combination of rectangle and triangle, a through hole is opened on the side of the equalizing flow distributor away from the airflow direction, and a hinge plate is arranged at the through hole, and limiting ribs are arranged on the hinge plate to prevent the hinge plate from being unable to reset after flipping upward more than 90° under the impact of airflow; 1 to n equalizing flow distributors are arranged in series or staggered; the bottom of the equalizing flow distributor is connected to the high-temperature flue gas inlet header; when the equalizing flow distributor is arranged above the furnace of the main coal-fired power station boiler, the equalizing flow distributor is arranged vertically along the left and right side walls.

[0015] Furthermore, when the high-temperature flue gas generated by the independent combustion of biomass is connected to the furnace wall and membrane wall of the main coal-fired power plant boiler through the high-temperature flue gas pipeline and sent into the furnace, when the mixed flue gas flow rate is small, a rectangular slit is cut on the flat steel in the middle of the membrane water-cooled wall tube, and the slits are staggered or arranged in sequence; or the thickness of the flat steel is increased to improve the flue gas jet stiffness, and the rectangular slit is cut; when the mixed flue gas flow rate is large and the flow area of ​​the rectangular slit does not meet the needs, some of the flat steel in the membrane water-cooled wall tube is removed, or the flat steel in the middle of the membrane water-cooled wall tube at the flue gas inlet is removed to directly pass the flue gas;

[0016] When the mixed flue gas flow rate increases further, one or more water pipes in the middle of the membrane water-cooled wall tube are cut off to replace the flow area occupied by one or more water pipes and one or more flat steels.

[0017] Furthermore, when the pre-biomass combustion boiler adopts a pressurized fluidized bed combustion boiler, a vertical cyclone separator is arranged at the flue gas outlet of the furnace of the pressurized fluidized bed combustion boiler, the cyclone separator is arranged on the inner side of the pressure shell, and the flue gas outlet of the vertical cyclone separator is connected to the mixing port.

[0018] Furthermore, when the high-temperature flue gas generated by the low-nitrogen combustion of the pre-installed biomass independent combustion boiler enters the furnace parallel to the center line of the membrane water-cooled wall or perpendicular to the center line of the membrane water-cooled wall when it is introduced into the furnace from the front and rear walls of the cold ash hopper of the main coal-fired power station boiler; when the flue gas enters the furnace from the two side walls, the flue gas inlet is parallel to the center line of the membrane water-cooled wall, and when the flue gas enters from the top, an upper triangular isobaric smoke bin is set on the two side walls, and when the flue gas enters from the bottom, a lower triangular isobaric smoke bin is set on the two side walls. When the pulverized coal preparation and pulverized coal combustion systems are completely disconnected and the high-temperature flue gas generated by the biomass combustion equipment 100% independently supports the safe operation of the main coal-fired power station boiler at a certain load ratio for a long period, in order to make full use of all the radiation heating surfaces of the main coal-fired boiler, the high-temperature flue gas generated by the low-nitrogen combustion of the pre-installed biomass independent combustion boiler must be preferentially introduced from the front and rear walls and the two side walls of the cold ash hopper of the main coal-fired power station boiler.

[0019] Furthermore, when the high-temperature flue gas generated after the low-nitrogen combustion of the pre-biomass independent combustion boiler is introduced into the furnace from the front and rear walls of the cold ash hopper of the main coal-fired power station boiler, it enters the furnace parallel to the center line of the membrane water-cooled wall or perpendicular to the center line of the membrane water-cooled wall; when the flue gas enters the furnace from the two side walls, the flue gas inlet is parallel to the center line of the membrane water-cooled wall, and when the flue gas enters from above, an upper triangular isobaric smoke chamber is set on the two side walls, and when the flue gas enters from below, a lower triangular isobaric smoke chamber is set on the two side walls.

[0020] The fixed bed layered combustion boiler A or the moving bed layered combustion boiler B also includes a slag discharge port, a primary air inlet, an ash hopper, a grate, a conveyor belt, a feed port, a secondary air inlet, and a tertiary air inlet; the feed port is connected to the conveyor belt, a secondary air inlet is arranged on the furnace wall above the feed port, a tertiary air inlet is arranged on the furnace wall on the side opposite to the secondary air inlet, a grate and a slag discharge port are arranged below the furnace, an ash hopper is arranged below the grate, and a primary air inlet is arranged on the grate; the fluidized bed combustion boiler C also includes a primary air inlet, a conveyor belt, an air distribution plate, a secondary air inlet, and a tertiary air inlet, the feed port of the fluidized bed combustion boiler is connected to the conveyor belt, a secondary air inlet is arranged on the furnace wall above the feed port, a tertiary inlet is arranged on the furnace wall on the side opposite to the secondary air inlet, an air distribution plate is arranged at the bottom of the furnace, and the air distribution plate is connected to the main secondary air duct A slag discharge port is arranged on the side below the furnace; in the main coal-fired power station boiler, starting from the top of the furnace, front and rear screen superheaters, high-temperature superheaters, high-temperature reheaters, turning smoke chambers, low-temperature reheaters, low-temperature superheaters, economizers, SCR reactors, plate air preheaters, induced draft fans, desulfurization towers and chimneys are arranged in sequence along the direction of the flue gas; a main secondary air duct is arranged at the air side outlet of the plate air preheater, a main secondary air baffle is arranged in the main secondary air duct, the outlet of the main secondary air duct is connected to the pulverized coal burner, the main secondary air duct is also connected to the separation secondary air duct, and the separation secondary air duct is connected to the pulverized coal burner and the secondary air inlet of the furnace above the pulverized coal burner; a blower is arranged at the air side inlet of the plate air preheater; the low-temperature reheater, the low-temperature superheater and the economizer are arranged in the tail shaft.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) The present invention installs a series of independent or combined biomass direct combustion, biomass fluidized combustion, biomass gasification post-combustion, and biomass catalytic gasification to produce hydrogen-rich post-combustion equipment near the main coal-fired power plant boiler of the coal-fired power generation unit. These equipment can be used independently or in combination. The products generated by all these independent or combined equipment are high-temperature flue gas after combustion;

[0023] (2) When biomass is mixed with combustion, independent or combined biomass direct combustion equipment shall directly send about 15% of the high-temperature flue gas generated after low-nitrogen combustion through the high-temperature flue through the gaps between the membrane water-cooled walls with flat steel pre-cut in the front, rear, left and right walls or the four corners of the cold ash hopper of the main coal-fired power station boiler, and send it into the lower area of ​​the furnace; about 30% shall directly enter the middle area of ​​the furnace of the main burner of the main coal-fired power station boiler through the high-temperature flue through the main secondary air duct, so as to achieve the recirculation of flue gas after the high-temperature flue gas and the secondary air are mixed to reduce the nitrogen oxides NO in the main combustion area. x; About 20% to 30% are directly sent to the upper area of ​​the furnace through the high-temperature flue through the separation secondary air duct of the main coal-fired power station boiler and the gaps between the membrane water-cooled walls with flat steel pre-cut on the front, rear, left and right walls or four corners of the upper part of the separation secondary air duct; About 15% are directly sent to the flue before the SCR reactor at the tail of the boiler through the flue to mix with the low-temperature flue gas to increase the flue gas temperature entering the SCR reactor to ensure the low-load denitrification efficiency in a reasonable temperature range. The mixed flue gas enters the SCR reactor together to implement the denitrification reaction, and then is discharged into the atmosphere through the chimney after dust removal and desulfurization in turn; When operating at low load or ultra-low load, about 30% to 50% are directly sent to the high-temperature heating surfaces of various levels through the high-temperature flue through the high-temperature superheater, high-temperature reheater and low-temperature superheater of the main coal-fired power station boiler through the equal flow distributor;

[0024] (3) The present invention can also completely decouple the coal powder preparation and coal powder combustion systems, and the high-temperature flue gas generated by the biomass combustion equipment can independently support the safe operation of the main coal-fired power station boiler at a certain load ratio for a long period. At this time, the main coal-fired power station boiler does not need to be introduced with primary air, secondary air and tertiary air. At this time, the fuel carbon emission of the entire main coal-fired power station boiler is zero, and zero carbon emission can be achieved. At this time, 15% of the high-temperature flue gas generated by the biomass combustion equipment should be sent into the gaps between the membrane water-cooled walls with flat steel pre-cut in the front, rear, left and right four walls or four corners of the cold ash hopper at the bottom of the main coal-fired power station boiler and sprayed into the lower area of ​​the furnace; about 40% should be sent into the main primary air duct and secondary air duct of the main coal-fired power station boiler through the high-temperature flue, and enter the middle area of ​​the furnace at the same time through the primary air and secondary air ports of the main burner of the power station boiler or in the form of four corners cut into circles or four walls cut into circles or the front and back walls hedged; about 25% directly passes through the high-temperature flue through the main coal-fired power station boiler The steam is sent to the upper area of ​​the furnace through the gaps in the membrane water-cooled walls with flat steel cut off in advance at the front, rear, left and right walls or four corners of the separated secondary air (SOFA) duct of the furnace and the upper part of the separated secondary air (SOFA) duct; 15% should be sent to the equal flow distributor in front of the high-temperature superheater and high-temperature reheater of the main coal-fired power station boiler and sent to the high-temperature heating surfaces of each level to ensure the steam outlet temperature of the high-temperature superheater and high-temperature reheater; and the remaining 5% or so is directly sent to the flue before the SCR reactor at the tail of the main coal-fired power station boiler to increase the flue gas temperature in the SCR reactor.

[0025] (4) The present invention can realize the intelligent control and dynamic control of the main coal-fired power station boiler unit coupled with several fixed bed layered combustion boilers, moving bed layered combustion boilers, fluidized bed combustion boilers, biomass pyrolysis furnaces, biomass gasification furnaces, etc., wherein the biomass pyrolysis furnace is also pre-pyrolyzed, and then the high-temperature flue gas after the pyrolysis gas is burned is sent to the various levels of flue gas mixing ports of the coal-fired power boiler through the high-temperature flue; wherein the biomass gasification furnace is also pre-pyrolyzed, and then the high-temperature flue gas after the gasification gas is burned is sent to the various levels of flue gas mixing ports of the coal-fired power boiler through the high-temperature flue. The present invention can realize the biomass blending and long-term operation of the main coal-fired power station boiler under different loads, and also realizes the cascade utilization of heat, ensuring the reasonable and efficient blending of biomass with coal-fired power units, achieving zero carbon emissions and minimum pollutant emissions.

[0026] (5) The present invention adopts various very traditional and mature pre-biomass independent combustion devices to carry out independent combustion of a single biomass fuel, whether it is layered combustion, fluidized bed combustion, biomass pyrolysis combustion, biomass gasification combustion and other combustion methods, and then directly sends the high-temperature flue gas produced after the independent combustion to the flue gas mixing ports of various levels of the main coal-fired power station boiler separately or after merging. It does not destroy the independent combustion of coal powder or lump coal in the main combustion zone of the main coal-fired power station boiler at all, and ensures the abnormal operating conditions such as biomass independent pulverizing explosion, biomass and coal powder mixed pulverizing explosion, coking, slagging, contamination, and blockage caused by the mutual restriction of high-carbon and low-carbon fuels with huge differences in combustion characteristics of coal and biomass, and completely avoids the traditional coal-fired power station boiler's low-proportion biomass blending method of mixing and burning biomass in the main combustion zone. The selected traditional pre-biomass independent combustion boiler has a fully mature low-nitrogen combustion technology. The biomass has undergone low-nitrogen combustion processes of air classification, fuel classification and flue gas recirculation in the pre-installed device. The high-temperature flue gas generated after combustion is further subjected to particle sedimentation in the furnace space and primary removal of fly ash and gas-dissolved particles in the flue gas by horizontal or vertical cyclone separators. The high-temperature flue gas generated after combustion in the traditional pre-biomass independent combustion boiler is sent to the furnace of the main coal-fired power plant boiler, and can be used to assist the main burner area to achieve flue gas recirculation to reduce NO in the combustion area. x, after being sent to the furnace, the various levels of heating surfaces are subjected to refined flue gas treatment such as SCR denitrification, dust removal by dust collector, and FGD desulfurization, thus completely realizing the ultra-clean emission of coal-fired power station boilers. The pre-biomass independent combustion boiler and the main coal-fired power station boiler burn independently, are multi-stage blended, organically combined, and complement each other, thus jointly realizing the low-carbon and zero-carbon technical transformation of coal-fired power generation units. The technical device and method proposed in the present invention greatly reduce the traditional unsafe operation mode of pre-forming the original ecological biomass into biomass shaped particles, then grinding the shaped biomass particles into biomass powder, and finally sending the biomass powder into the main burner area of ​​the furnace of the main coal-fired boiler and the slagging, coking, contamination and high-temperature corrosion that occur during the coal powder blending process, while avoiding the disadvantages of high-cost pre-treatment and low blending ratio of the main coal-fired power station boiler blending biomass. The present invention not only realizes the coordinated blending of high-temperature flue gas after independent combustion of biomass with the main coal-fired power station boiler to realize joint power generation, cogeneration and centralized heating, but the mixed flue gas also realizes subsequent flue gas purification treatment of coordinated denitrification, dust removal and desulfurization. At the same time, an air preheating interlayer is arranged in the furnace wall of various pre-biomass independent combustion boilers to heat the cold air entering the blower inlet of the main coal-fired power station boiler, thereby increasing the inlet air temperature of the air preheater, reducing and avoiding low-temperature corrosion of the cold end of the air preheater, and also achieving long-term safe operation of the coordinated blending of air between the pre-biomass independent combustion boiler and the main coal-fired power station boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention proposes a technical device and method for an independent combustion of biomass and synergistic blending coal-fired power station boiler, which is a schematic diagram of the overall system structure combining a fixed bed layered combustion boiler, a moving bed layered combustion boiler, a fluidized bed combustion boiler and a main coal-fired power station boiler.

[0028] Figure 2 This is a technical device and method for independently burning biomass and mixing high-temperature flue gas with a main coal-fired power station boiler. One or more fixed-bed layered combustion boilers or moving-bed layered combustion boilers are arranged with high-temperature tubular air preheaters to generate high-temperature air, thereby injecting high-temperature flue gas into the main coal-fired power station boiler.

[0029] Figure 3a The present invention is a technical device and method for independently burning biomass high-temperature flue gas mixed with the main coal-fired power station boiler. The high-temperature flue gas is first roughly separated by horizontal cyclone separation, and then the high-temperature flue gas generated by the fixed bed layered combustion boiler or the moving bed layered combustion boiler is ejected by a high-temperature air ejector to be sent into the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces of various levels and the mixing port of the tail flue; Figure 3bIt is a structural schematic diagram of a fixed bed layered combustion boiler or a moving bed layered combustion boiler with an inwardly extending boss at the outlet. When the high-temperature flue gas passes through the boss, it is roughly separated by rotating around the boss. The unburned solids in the high-temperature flue gas directly fall into the furnace and continue to burn. The high-temperature flue gas is sent to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces of each level and the mixing port of the tail flue.

[0030] Figure 4 This is a structural schematic diagram of a technical device and method for independently burning biomass and mixing high-temperature flue gas with a main coal-fired power station boiler, which uses a high-temperature air ejector to eject the high-temperature flue gas generated by a fluidized bed combustion boiler into the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces at various levels and the mixing port of the tail flue.

[0031] Figure 5 The present invention is a technical device and method for mixing the high-temperature flue gas generated by a pre-installed biomass independent combustion boiler with the main coal-fired power station boiler. The high-temperature flue gas generated by the independent combustion of one or several fixed-bed layered combustion boilers or moving bed layered combustion boilers or the independent combustion of normal-pressure fluidized bed combustion boilers, or the high-temperature flue gas independently combusted by the layered combustion boiler and the fluidized bed combustion boiler are mixed and then concentrated by a high-temperature and high-pressure induced draft fan to provide a pressure head and distribute it along the mixing port of the main coal-fired power station boiler at different positions according to proportion requirements to the mixing ports of the main coal-fired power station boiler and the subsequent heating surfaces at all levels and the tail flue. Schematic diagram of the result.

[0032] Figure 6 The present invention is a technical device and method for mixing high-temperature flue gas of independent combustion of biomass with the main coal-fired power station boiler. If one or several pressurized fluidized bed combustion boilers provide their own power, the high-temperature flue gas generated by their independent combustion is distributed along mixing ports at different positions according to proportional requirements and sent into the mixing ports of the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces of various levels and the tail flue.

[0033] Figure 7a is a schematic diagram of a layered combustion burner in the pre-biomass independent combustion boiler; Figure 7b It is a partial cross-sectional enlarged view of the shell of the pre-biomass independent combustion boiler.

[0034] Figure 8a It is a schematic cross-sectional view of the position of high-temperature flue gas entering the furnace from the front and rear walls of the cold ash hopper of the main coal-fired power station boiler; Figure 8b It is a cross-sectional schematic diagram of the flue gas entry position when the high-temperature flue gas enters the furnace from the two side walls of the cold ash hopper of the main coal-fired power station boiler.

[0035] Figure 9aIt is a cross-sectional schematic diagram of the position of flue gas introduction when high-temperature flue gas is introduced into the furnace from the front and rear walls of the flame deflection angle above the secondary air duct separated from the main coal-fired power station boiler; Figure 9b It is a cross-sectional schematic diagram of the flue gas delivery position when high-temperature flue gas is delivered into the furnace from the walls on both sides of the flame deflection angle above the secondary air duct separated from the main coal-fired power station boiler.

[0036] Fig.10a It is a structural schematic diagram of the arrangement of the flow distributor in front of the high-temperature reheater, the low-temperature superheater and the low-temperature reheater; Fig.10b It is a schematic diagram of a cross-sectional structure in which a flow distributor is arranged in front of a high-temperature reheater, a low-temperature superheater and a low-temperature reheater; Fig.10c This is a schematic diagram of the structure of the flow distributor arranged in series with the horizontal pipeline in front of the SCR reactor; Fig.10d It is a schematic diagram of the cross-sectional structure of the flow distributor arranged in series with the horizontal pipeline in front of the SCR reactor; Fig.10e This is a schematic diagram of the structure of the staggered arrangement of the horizontal pipelines in front of the SCR reactor for the equal flow distributor; Fig.10f This is a schematic diagram of the top view and cross-sectional structure of the flow distributor in the staggered arrangement of horizontal pipes in front of the SCR reactor.

[0037] Fig.11a and Fig.11b It is a structural schematic diagram of a movable hinge plate installed on the leeward wall surface of a flow equalizing distributor.

[0038] Fig.12a It is a structural diagram of removing part of the flat steel; Figure 12b This is a schematic diagram of the structure in which the middle water pipe of the water-cooled wall is removed and replaced with a bent pipe; Fig.12c It is a schematic diagram of the structure in which part of the water-cooled wall tubes are pulled outward; Fig.12d It is a schematic diagram of the structure of using laser to cut staggered narrow gaps on flat steel; Fig.12e This is a schematic diagram of the structure of using laser to cut out narrow gaps in a row on flat steel.

[0039] Fig.13a It is a structural schematic diagram of a horizontal cyclone separator arranged at a high-temperature flue gas outlet of a fixed-bed layered combustion boiler or a moving-bed layered combustion boiler; Fig.13b It is a schematic diagram of the cross-sectional structure of the flue gas of a horizontal cyclone separator from a top view; Fig.13c It is a structural schematic diagram of a moving bed layered combustion boiler with a rotating boss at the high temperature flue gas outlet. Fig.13d The utility model is a top view cross-sectional structural schematic diagram of a moving bed layered combustion boiler in which a rotating boss is arranged at a high temperature flue gas outlet.

[0040] The numbers shown in the figure are: 1-slag discharge port, 2-primary air inlet, 3-ash hopper, 4-grate, 5-conveyor belt, 6-feed port, 7-secondary air inlet, 8-tertiary air inlet, 9-material leg, 10-horizontal cyclone separator, 11-flocculant injection device, 12-high-temperature tubular air preheater, 13-high-temperature air outlet header, 14-high-temperature air ejector, 15-coal powder burner, 16-separation secondary air duct, 17-high-temperature flue gas adjustment baffle, 18-flange, 19-front and rear screen superheater, 20-flow distributor, 21-high-temperature superheater, 22-high-temperature reheater, 23-turning smoke chamber, 24-low-temperature reheater, 25-low-temperature superheater, 26-tail shaft, 27-economizer, 28-SCR reactor, 29-chimney, 30-desulfurization tower, 31-induced draft fan, 32-plate air preheater, 33-main secondary air air baffle, 34-main secondary air duct, 35-blower, 36-cold ash hopper, 37-rotating boss, 38-air distribution plate, 39-return device, 40-vertical pipe, 41-vertical cyclone separator, 42-high temperature and high pressure induced draft fan, 43-maintenance manhole, 44-pressure shell, 45-start combustion chamber, 46-fuel injection port, 47-membrane water-cooled wall tube, 48-flat steel, 49-hinge plate, 50-high temperature air inlet header, 51-grabbing nails, 52-refractory material, 53-insulating material layer, 54-inner supporting steel plate, 55-air preheating interlayer, 56-outer supporting steel plate, 57-insulating layer, 58-limiting ribs. DETAILED DESCRIPTION

[0041] The technical concept of the present invention is to directly send the high-temperature flue gas generated by the low-nitrogen combustion of the front biomass independent combustion boiler to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces at all levels and the mixing ports of the tail flue according to the flue gas temperature adjustment requirements, and cross-mix it evenly with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler. The maximum 100% mixed biomass low-load or ultra-low load flexibility transformation and long-term safe operation can be achieved. After the high-temperature flue gas of the front biomass independent combustion is mixed with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler, the SCR denitrification reactor, dust collector and FGD desulfurization tower arranged in the tail flue of the main coal-fired power station boiler respectively complete the denitrification, dust removal and desulfurization requirements, thereby completing the ultra-low emission of the main coal-fired power station boiler and then discharged into the atmosphere from the chimney. The front biomass independent combustion boiler only generates high-temperature flue gas to transport the main coal-fired power station boiler, and does not need to be independently configured with flue gas purification equipment. The pre-placed biomass independent combustion boiler and the main coal-fired power station boiler realize independent combustion of different fuels, multi-stage blending, organic combination, and mutual complementation, and jointly realize the low-carbon and zero-carbon technical transformation of coal-fired power units. In addition to being used for coal-fired pulverized coal combustion boilers, atmospheric pressure fluidized bed combustion boilers that burn granular or lumpy coal particles, and pure condensing power generation units of main coal-fired power station boilers of other fossil fuels, the present invention is also suitable for any cogeneration boiler unit, and is also suitable for any industrial steam boiler and hot water boiler for centralized heating that burns fossil fuels.

[0042] When the pre-placed biomass independent combustion boiler and the main coal-fired power station boiler are actually running in joint blending, the damper can be opened or closed according to different blending conditions, or the opening of the high-temperature flue gas regulating damper can be adjusted according to the proportional requirements to achieve the purpose of mixing the high-temperature flue gas ratio. All high-temperature flue gas regulating dampers are driven by servo motors to perform intelligent adjustment and control of the combustion load of the pre-placed biomass independent combustion boiler and the high-temperature flue gas regulating damper according to the load change requirements of the main coal-fired power station boiler.

[0043] In Example 1, the flue gas generated by the independent combustion of biomass is introduced into the mixing port of the main coal-fired power plant boiler according to a set mixing ratio, and the mixing port is opened in the lower, middle, and upper areas of the furnace of the main coal-fired power plant boiler and the heating surfaces of various levels downstream of the furnace and the tail flue; the air becomes high-temperature air after heat exchange with the high-temperature flue gas, and the high-temperature air is used to guide the flue gas generated by the independent combustion of biomass; or the pressurized flue gas generated by the independent combustion of biomass is directly sent to the mixing port; or the flue gas generated by the independent combustion of biomass is pressurized and sent to the mixing port. The details are as follows: the high-temperature flue gas generated after the low-nitrogen combustion of the pre-biomass independent combustion boiler passes through a horizontal or vertical cyclone separator for gas-solid separation and primary flue gas purification, and then the flue gas temperature is reduced to about 500°C after passing through the high-temperature tubular air preheater 12. The cooled flue gas is passed through a flue gas duct into the horizontal flue in front of the SCR reactor 28 at the tail end of the coal-fired power plant boiler, and is mixed with the medium-temperature mainstream flue gas generated after the combustion of the coal-fired power plant boiler and cooled by heat exchange on various levels of heating surfaces, so as to increase the temperature of the mainstream flue gas entering the SCR reactor 28 to a temperature level suitable for the SCR catalyst for denitrification. A high-temperature air outlet header 13 is arranged next to the flue gas outlet pipe of the high-temperature flue gas generated after the low-nitrogen combustion of the pre-placed biomass independent combustion boiler. A row of high-temperature air ejectors 14 are arranged on the high-temperature air outlet header 13. The high-temperature hot air heated by the high-temperature tubular air preheater 12 enters the high-temperature air outlet header 13, and then the high-temperature flue gas discharged from other pre-placed biomass independent combustion boilers is ejected through the high-temperature air ejectors 14 distributed thereon and sent into the mixing port of the main coal-fired power station boiler to be evenly cross-mixed with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler, and the high-temperature flue gas ejected by the high-temperature air provides power for the main coal-fired power station boiler to burn biomass;

[0044] Or the high-temperature flue gas generated by the low-nitrogen combustion of the front biomass independent combustion boiler is mixed and concentrated by a high-temperature and high-pressure induced draft fan 42 that can withstand a temperature of 1000°C to provide pressure and distribute it in proportion to the mixing port of the main coal-fired power station boiler to cross-mix it evenly with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler; the primary air, secondary air and tertiary air required by the main coal-fired power station boiler and the moving bed layered combustion boiler are all provided by the tail blower of the main coal-fired power station boiler, and the air provided by the blower is preheated by the air preheater and then enters the primary air, secondary air and tertiary air inlet of the main coal-fired power station boiler and the moving bed layered combustion boiler;

[0045] Or one or more pressurized circulating fluidized bed boilers are set up to provide power by themselves, and the high-temperature flue gas generated by their independent combustion is distributed according to the required proportion and sent to the mixing port of the main coal-fired power station boiler to be cross-mixed evenly with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler.

[0046] In Example 2, the front-end biomass independent combustion boiler is arranged with one or more moving bed layered combustion boilers or atmospheric fluidized bed combustion boilers, and one or more biomass pyrolysis furnaces, biomass gasification furnaces and atmospheric fixed bed straw gasification furnaces can also be arranged according to the situation. Among them, the front-end biomass independent combustion boilers all adopt low-nitrogen combustion biomass independent combustion boilers based on air staging, fuel staging and flue gas recirculation coupling to reduce NO of the front-end biomass independent combustion boiler. x Emissions can reduce the denitrification pressure of the ultra-low emission SCR reactor at the tail of the main coal-fired power station boiler. The nitrogen-reducing recycled flue gas used by the pre-biomass independent combustion boiler comes from several pre-biomass independent combustion boilers themselves.

[0047] The biomass pyrolysis furnace also pre-pyrolyzes the biomass, and then the high-temperature flue gas directly produced by the combustion of the pyrolysis gas is sent to the flue gas mixing ports of various levels of the main coal-fired electric boiler through the high-temperature flue gas pipeline; the biomass gasification furnace and the atmospheric pressure fixed bed straw gasification furnace also pre-gasify the biomass, and then the high-temperature flue gas directly produced by the combustion of the gasification gas is sent to the flue gas mixing ports of various levels of the coal-fired electric boiler through the high-temperature flue gas pipeline; in the specific implementation, based on the above implementation method, the biomass raw material particles are sorted according to their size, and the moving bed layered combustion boiler or the atmospheric pressure fluidized bed combustion boiler can be selected respectively. Boiler or pyrolysis furnace or gasification furnace, such as sending larger biomass raw materials such as straw to the moving bed layered combustion boiler for combustion; and sending smaller biomass raw materials such as shells to the atmospheric fluidized bed combustion boiler for combustion; when there is domestic sludge to be treated at the location of the main coal-fired power station boiler, the wet sludge with a water content of 80% can be first dried by steam or other means of thermal energy to reduce its water content to 35% to 40%, and then the dried sludge is directly sent to the atmospheric fluidized bed combustion boiler for direct combustion, and the high-temperature flue gas generated is sent to the main coal-fired power station boiler for mixing.

[0048] On the basis of the above embodiments, the high-temperature flue gas generated by the pre-mounted biomass independent combustion boiler, whether it is layered combustion or fluidized bed combustion, must pass through a horizontal or vertical cyclone separator for gas-solid separation and primary flue gas purification before being sent to the high-temperature flue gas pipeline for transportation to the main coal-fired power station boiler for mixing, so as to reduce the fly ash particles or aerosols generated by the direct combustion of biomass adhering to the inner wall of the high-temperature pipeline and the mixing port. It is also possible to use a flocculant injection device 11 before the horizontal or vertical cyclone separator to spray flocculants into the flue gas after combustion to promote the large particle aggregation of fly ash aerosol particles so as to reduce the fly ash aerosol particles in the flue gas. The flocculant can be removed from the horizontal or vertical cyclone separator after the layered combustion boiler (horizontal as shown in the figure) and the fluidized bed combustion boiler (vertical as shown in the figure) by interchanging the horizontal cyclone separator and the vertical cyclone separator according to the different requirements of separation efficiency and the outlet direction of the high-temperature flue gas. The high-temperature flue gas after independent combustion in the layered combustion boiler and the fluidized bed combustion boiler rises vertically in the furnace to the turning throat of the horizontal flue and is sprayed into the high-temperature flue gas, that is, it is sprayed into the high-temperature flue gas at the narrow part of the horizontal flue before the cyclone separator to condense and aggregate the fly ash particles and aerosols, and then the large particles are separated by the cyclone separator.

[0049] The advantage of arranging multiple pre-biomass independent combustion boilers in parallel is that when one or several of the boilers fail, it will not affect the operation of the overall system of the main coal-fired power station boiler. One or several pre-biomass independent combustion boilers can be shut down for maintenance to ensure the long-term operation of the overall system and to achieve full-scale coupling and co-firing of the pre-biomass independent combustion boilers and the main coal-fired power station boiler; at the same time, the output power can also be adjusted.

[0050] Example 3

[0051] The high-temperature flue gas generated by the low-nitrogen combustion of the pre-biomass independent combustion boiler is directly sent to the middle area of ​​the furnace of the main burner of the main coal-fired power station boiler through the high-temperature flue gas duct and the main secondary air duct. The secondary air temperature is increased by the mixed high-temperature flue gas, which assists in strengthening the pulverized coal particle combustion in the main burner area of ​​the main coal-fired power station boiler, strengthens the radiation heat exchange in the main burner area, and reduces the nitrogen oxides NO in the main combustion area by mixing the high-temperature flue gas and the secondary air. x generate.

[0052] The high-temperature flue gas generated after the low-nitrogen combustion of the pre-biomass independent combustion boiler is mixed with the mainstream flue gas from the upper part of the burner of the main coal-fired power station boiler. One of them can be directly sent into the upper area of ​​the furnace from the port 16 of the separation secondary air duct on the top of the burner for mixing; the other can be sent from the top of the separation secondary air duct 16 port to the flame folding angle and the front and rear walls below it to be sent to the furnace at a set inclination angle to be mixed with the mainstream flue gas. Similarly, the walls on both sides of the flame folding angle are also sent to the furnace at a set inclination angle to be mixed with the mainstream flue gas. The high-temperature flue gas is sent into the furnace from the front and rear walls and the two side walls in a "W"-shaped cross-mixing flow, which strengthens the mixing of the high-temperature flue gas generated by coal combustion and the high-temperature flue gas generated by burning biomass. At the same time, it can be evenly sent to the temperature field of the upper screen superheater to reduce the unevenness of the flue gas temperature sent to the bottom of the screen superheater.

[0053] Example 4

[0054] The main coal-fired power station boiler unit is combined with the biomass independent combustion boiler flue gas mixing system to set up one or more fixed bed layered combustion boilers or moving bed layered combustion boilers and normal pressure fluidized bed combustion boilers. The blower pressure head provided by the main coal-fired power station boiler will send the positive pressure primary air, secondary air or tertiary air heated by the air preheater from the main coal-fired power station boiler blower to generate high-temperature flue gas after combustion. The high-temperature flue gas is distributed along the mixing ports at different positions according to the proportion requirements and sent to the main coal-fired power station boiler. The mixing ports are located in the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces and tail flue at all levels; when mixing biomass, the primary air, secondary air and tertiary air required by the main coal-fired power station boiler and the moving bed layered combustion boiler are all provided by the tail blower 35 of the main coal-fired power station boiler. The air provided by the blower 35 is preheated by the air preheater and enters the primary air, secondary air and tertiary air inlets of the main coal-fired power station boiler and the moving bed layered combustion boiler.

[0055] When the main coal-fired power station boiler is running at ultra-low load and there is a water circulation safety fault or it is not suitable for long-term ultra-low load operation, when the main coal-fired power station boiler is running at low load or when the coal powder preparation and coal powder combustion system are completely disconnected, the high-temperature flue gas generated by the biomass combustion equipment is independently supported by the main coal-fired power station boiler to run safely for a long period at a certain load ratio, at this time, the main secondary air front flue gas damper is opened, and the main secondary air air damper 33 is closed, wherein a part of the high-temperature flue gas generated by one or more moving bed layered combustion boilers is passed through the gaps in the membrane water-cooled wall flat steel that have been pre-cut in front, rear and two side walls or four corners of the main coal-fired power station boiler cold ash hopper. The super-high-temperature air is sent into the furnace through the ejector, and the other part is sent into the furnace through the secondary air inlet of the pulverized coal burner or in the form of four-corner circular cutting, four-wall circular cutting, and front and rear wall hedging. At this time, the main coal-fired power station boiler does not need primary air, secondary air, and tertiary air. The air provided by the tail blower of the main coal-fired power station boiler is only used to provide the primary air, secondary air, and tertiary air required by the moving bed layered combustion boiler and the fluidized bed combustion boiler; the main coal-fired power station boiler only relies on the high-temperature flue gas mixed with the low-nitrogen combustion of the front biomass independent combustion boiler to maintain the long-term safe operation of the main coal-fired power station boiler, and realize 100% biomass blending and low-load operation.

[0056] like Figure 2 As shown, one or more moving bed layered combustion boilers are provided with a high-temperature tubular air preheater 12 at the high-temperature flue gas outlet. After the high-temperature flue gas at 1000°C passes through the horizontal cyclone separator 10 for rough gas-solid separation, the flue gas is cooled to 500°C through the high-temperature tubular air preheater 12, and the air is heated to above 900°C. The cooled flue gas is introduced into the equalizing flow distributor 20 in the horizontal pipeline in front of the SCR reactor. The equalizing flow distributor 20 is vertically arranged in the horizontal pipeline, and the rear surface of the equalizing flow distributor 20 is perforated. A high-temperature flue gas inlet header 50 is arranged at the lower end of the equalizing flow distributor 20. The low-temperature flue gas after heat exchange in the moving bed layered combustion boiler is discharged from the equalizing flow distributor 20. The high-temperature flue gas enters the high-temperature flue gas inlet header 50 at the lower end of the distributor 20, and is sucked into the horizontal pipeline in front of the SCR reactor of the main coal-fired power station boiler by the induced draft fan at the rear end of the main coal-fired power station boiler to mix with the flue gas generated by the main coal-fired power station boiler. The heated air enters the high-temperature air outlet header 13, and a high-temperature air ejector 14 is arranged on the high-temperature air outlet header 13. The pipeline where the high-temperature air ejector 14 is located is connected to the high-temperature flue gas pipeline. The high-temperature air is sent to the mixing port of the main coal-fired power station boiler by ejecting the high-temperature flue gas, and then sent to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces of various levels and the mixing ports of the tail flue.

[0057] refer to Figure 1 , Figure 2The biomass combustion boiler includes one or more fixed bed layer combustion boilers A or moving bed layer combustion boilers B that independently burn biomass or one or more normal pressure fluidized bed combustion boilers C and a fixed bed layer combustion boiler A or moving bed layer combustion boiler B, normal pressure fluidized bed combustion boiler C combined boiler system; including a high temperature air outlet header 13, a high temperature air ejector 14, a pulverized coal burner 15, a separation secondary air duct 16, a high temperature flue gas regulating baffle 17, a flange 18, front and rear screen superheaters 19, an equal flow distributor 20, a high temperature superheater 21, a high temperature reheater 22, a turning smoke chamber 23, a low temperature reheater 24, a low temperature superheater 25, a tail shaft 26, an economizer 27, and an SCR reactor 28 , chimney 29, desulfurization tower 30, induced draft fan 31, plate air preheater 32, main secondary air air damper 33, main secondary air duct 34, blower 35, cold ash hopper 36, high temperature and high pressure induced draft fan 42; a high temperature air outlet header 13 and a high temperature air ejector 14 are arranged in the flue leading to the mixing port of the biomass combustion boiler, the air inlet of the high temperature air ejector 14 is connected to the high temperature tubular air preheater 12, and the outlet of the high temperature air ejector 14 is arranged in the flue leading to the mixing port; the pulverized coal burner 15, the separation secondary air duct 16, the high temperature superheater 21, the high temperature reheater 22 and the horizontal flue before the inlet of the SCR reactor of the main coal-fired power station boiler are all connected to the flue gas outlet of the biomass combustion boiler.

[0058] refer to Figure 2 In the main coal-fired power station boiler, the pulverized coal burner 15 is arranged in the middle and lower part of the furnace. From the top of the furnace, along the direction of the flue gas, the front and rear screen superheaters 19, the flow distributor 20, the high-temperature superheater 21, the high-temperature reheater 22, the turning smoke chamber 23, the low-temperature reheater 24, the low-temperature superheater 25, the economizer 27, the SCR reactor 28, the plate air preheater 32, the induced draft fan 31, the desulfurization tower 30 and the chimney 29 are arranged in sequence; the air side outlet of the plate air preheater 32 is provided with the main two A secondary air duct 34, a main secondary air air baffle 33 is arranged in the main secondary air duct 34, the outlet of the main secondary air duct 34 is connected to the pulverized coal burner 15, and the main secondary air duct 34 is also connected to the separation secondary air duct 16, and the separation secondary air duct 16 is connected to the pulverized coal burner 15 and the furnace secondary air inlet above the pulverized coal burner 15; a blower 35 is arranged at the air side inlet of the plate air preheater 32; the low-temperature reheater 24, the low-temperature superheater 25, and the economizer 27 are arranged in the tail shaft 26.

[0059] refer to Figure 2The moving bed layered combustion boiler A comprises a slag discharge port 1, a primary air inlet 2, an ash hopper 3, a grate 4, a conveyor belt 5, a feed port 6, a secondary air inlet 7, a tertiary air inlet 8, a feed leg 9, a horizontal cyclone separator 10, a flocculant injection device 11, a high-temperature tubular air preheater 12, and a rotating boss 37; the feed port 6 is connected to the conveyor belt 5, a secondary air inlet 7 is arranged on the furnace wall above the feed port 6, a tertiary air inlet 8 is arranged on the furnace wall opposite to the secondary air inlet 7, a grate 4 and a slag discharge port 1 are arranged below the furnace, an ash hopper 3 is arranged below the grate 4, a primary air inlet 2 is arranged on the grate 4, and a furnace flue gas outlet is connected to a horizontal cyclone. The air separator 10, the particle outlet of the horizontal cyclone separator 10 is connected to the furnace through the material return 9, the flue gas outlet of the horizontal cyclone separator 10 is connected to the flue gas inlet of the high-temperature tubular air preheater 12, the flue gas outlet of the high-temperature tubular air preheater 12 is connected to the horizontal pipeline in front of the inlet of the SCR reactor 28 of the main coal-fired boiler, the high-temperature air outlet of the high-temperature tubular air preheater 12 is provided with a high-temperature air outlet header 13, the high-temperature air outlet header 13 is connected to the high-temperature air ejector 14, and the air inlet of the high-temperature tubular air preheater 12 is connected to the air preheater; the flue gas pipeline where the high-temperature air ejector 14 is located is connected to the mixing port.

[0060] The grate in the moving bed layered combustion boiler is a chain moving grate, a reciprocating moving grate or a water-cooled vibrating grate; the atmospheric pressure fluidized bed combustion boiler adopts a boiling fluidized bed combustion boiler, an internal circulation fluidized bed combustion boiler or an external circulation fluidized bed combustion boiler.

[0061] refer to Figure 3a A flocculant injection device 11 is arranged at the flue gas outlet of the moving bed layered combustion boiler B, the flue gas outlet of the moving bed layered combustion boiler B is connected to the flue gas inlet of the horizontal cyclone separator 10, the flue gas outlet of the horizontal cyclone separator 10 is connected to the mixing port on the main coal-fired power station boiler through a flue gas pipeline, a high-temperature air ejector 14 is arranged in the flue gas outlet pipeline of the horizontal cyclone separator 10, and the high-temperature air ejector 14 is connected to the high-temperature air outlet header 13; the flue gas generated by one or more independently arranged moving bed layered combustion boilers is heat-exchanged with air to obtain 900°C high-temperature air, and the high-temperature flue gas generated by the moving bed layered combustion boiler B is sent to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the mixing ports of the subsequent heating surfaces and the tail flue at various levels.

[0062] refer to Figure 3b, a flocculant injection device 11 and a rotating boss 37 extending inward are arranged inside the flue gas outlet of the moving bed layered combustion boiler B, the rotating boss 37 is connected to the mixing port on the main coal-fired power station boiler through the high-temperature flue gas pipeline, a high-temperature air ejector 14 is arranged in the high-temperature flue gas pipeline, and the high-temperature air ejector 14 is connected to the high-temperature air outlet header 13. The flue gas generated by one or more independently arranged moving bed layered combustion boilers is heat exchanged with air to obtain 900°C high-temperature air, and the high-temperature flue gas generated by the moving bed layered combustion boiler B is sent to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces of various levels and the mixing port of the tail flue.

[0063] like Figure 3a and Figure 3b As shown in the figure, when the blower pressure head provided by the main coal-fired power station boiler is not enough to distribute the high-temperature flue gas into the mixing port of the main coal-fired power station boiler, the high-temperature flue gas of about 1000°C generated by one or more moving bed layered combustion boilers is first roughly separated by a horizontal cyclone separator, and then the flue gas generated by one or more independently set moving bed layered combustion boilers is heat-exchanged with air to obtain 900°C high-temperature air, and the high-temperature flue gas of about 1000°C is ejected by the 900°C high-temperature air into the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces at all levels and the mixing port of the tail flue.

[0064] like Fig.13a and 13b As shown, a horizontal cyclone separator 10 is arranged at the high-temperature flue gas outlet of the moving bed layered combustion boiler for rough gas-solid separation. After entering the cyclone tube, the high-temperature flue gas rotates around the central tube, and the unburned solids return to the moving bed layered combustion boiler through the material leg 9. The high-temperature flue gas enters the high-temperature flue gas pipeline from the side through the central tube and is distributed along the mixing ports of the main coal-fired power station boiler at different positions according to the proportion requirements to enter the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces at all levels and the mixing ports of the tail flue. Fig.13c and 13dAs shown, a rotating boss 37 extending inward is set at the high-temperature flue gas outlet of the moving bed layered combustion boiler. The high-temperature flue gas rotates under the disturbance of the rotating boss 37, and the unburned solids directly fall onto the grate of the moving bed layered combustion boiler and continue to burn. The rotating boss can be set 1 to n according to the width of the moving grate layered combustion boiler. Finally, the high-temperature flue gas is collected into a pipeline and enters the high-temperature flue gas pipeline through the central tube of the rotating boss 37. The high-temperature flue gas is distributed along the mixing ports of the main coal-fired power station boiler at different positions according to the proportion requirements and sent to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces and the mixing ports of the tail flue. In addition, the length L1 of the central tube of the horizontal cyclone separator and the length L2 of the rotating boss can be changed. The longer L1 and L2 are, the higher the gas-solid separation efficiency of the high-temperature flue gas before entering the high-temperature flue gas pipeline, but the greater the resistance is. On the contrary, the shorter L1 and L2 are, the lower the gas-solid separation efficiency of the high-temperature flue gas before entering the high-temperature flue gas pipeline, and the lower the resistance is.

[0065] refer to Figure 4 The fluidized bed combustion boiler B comprises a primary air inlet 1, a conveyor belt 5, an air distribution plate 38, a secondary air inlet 7, a tertiary air inlet 8, a flocculant injection device 11, a return device 39, a riser 40 and a cyclone separator 41. The feed inlet of the fluidized bed combustion boiler is connected to the conveyor belt 5, a secondary air inlet 7 is arranged on the furnace wall above the feed inlet, a tertiary inlet 8 is arranged on the furnace wall on the side opposite to the secondary air inlet, the furnace flue gas outlet is connected to the cyclone separator 41, and a flocculant is arranged in front of the flue gas inlet of the cyclone separator 41. The injection device 11, the flue gas outlet of the cyclone separator 41 is connected to the mixing port on the main coal-fired power plant boiler through the high-temperature flue gas pipeline, the high-temperature flue gas pipeline is connected to the high-temperature air ejector 14, and the high-temperature air ejector 14 is connected to the high-temperature air outlet header 13; the particle outlet of the cyclone separator 41 is connected to the return device 39 through the riser 40, the return device 39 is connected to the furnace, and the air distribution plate 38 is arranged at the bottom of the furnace, and the air distribution plate 38 is connected to the main secondary air pipeline 34 through the pipeline, and the slag discharge port 1 is arranged on the lower side of the furnace.

[0066] like Figure 4 As shown, when the blower pressure head provided by the main coal-fired power station boiler is insufficient to overcome the resistance of the high-temperature flue gas distribution and delivery to the mixing port of the main coal-fired power station boiler, at this time, one or more fluidized bed combustion boilers generate high-temperature flue gas of not less than 850°C, and one or more independently arranged moving bed layered combustion boilers generate high-temperature air of more than 900°C through flue gas and air heat exchange, and the high-temperature air is used to guide the high-temperature flue gas of not less than 850°C into the mixing port of the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces of various levels and the tail flue.

[0067] refer to Figure 5A horizontal cyclone separator 10 is arranged at the flue gas outlet of the moving bed layered combustion boiler A, and a vertical cyclone separator 41 is arranged at the flue gas outlet of the atmospheric pressure fluidized bed combustion boiler B. The flue gas outlets of the horizontal cyclone separator 10 and the vertical cyclone separator 41 are connected to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the mixing ports of the subsequent heating surfaces and the tail flue through the high-temperature and high-pressure induced draft fan 42.

[0068] like Figure 5 As shown, the high-temperature flue gas generated by the independent combustion of one or more moving bed layered combustion boilers or the independent combustion of normal pressure fluidized bed combustion boilers, or the high-temperature flue gas independently combusted by the layered combustion boiler and the fluidized bed combustion boiler are mixed and concentrated by a high-temperature and high-pressure induced draft fan 42 to provide a pressure head and distribute it along the mixing ports of the main coal-fired power station boilers at different positions according to the proportion requirements to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces at all levels and the mixing ports of the tail flue. The operating temperature of the high-temperature and high-pressure induced draft fan is about 1000°C.

[0069] refer to Figure 6 The pressurized fluidized bed combustion boiler includes a pressure shell 44, a maintenance manhole 43 is provided on the pressure shell 44, a starting combustion chamber 45 is provided below the furnace, and a fuel injection port 46 is provided on the starting combustion chamber 45; a vertical cyclone separator 41 is provided at the flue gas outlet of the furnace, and the cyclone separator 41 is provided on the inner side of the pressure shell 44, and the particle outlet of the cyclone separator 41 is connected to the return device 39 through the vertical pipe 40, and the return device 39 is connected to the furnace, and an air distribution plate 38 is provided at the bottom of the furnace, and the air distribution plate 38 is connected to the main secondary air duct 34 through a pipeline.

[0070] like Figure 6 As shown, one or more fluidized bed combustion boilers are pressurized fluidized bed combustion boilers with extremely good sealing performance. The 850℃ high-temperature flue gas generated inside them relies on its own internal high pressure to provide power to distribute the high-temperature flue gas generated by each independent combustion along the mixing ports at different positions according to the proportion requirements and send it to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces at all levels and the mixing ports of the tail flue.

[0071] like Figure 7a and Figure 7b As shown, the furnace wall structure of all pre-biomass independent combustion boilers is set to six layers, from the inside of the high-temperature flue gas to the air side outside the furnace body, respectively: refractory material 52, insulation material layer 53, inner support steel plate 54, air preheating interlayer 55, outer support steel plate 56, insulation layer 57, wherein the inner support steel plate is welded with grab nails 51 for fixing the refractory material. Figure 7b for Figure 7a Schematic diagram of the cross-sectional structure of the furnace wall at middle Q.

[0072] like Figure 8aAs shown, the high-temperature flue gas enters the furnace of the main coal-fired power station boiler from the front and rear walls of the cold ash hopper 36 vertically or parallel to the center line of the membrane water-cooled wall; Figure 8b As shown, high-temperature flue gas enters the furnace of the main coal-fired power plant boiler from the two side walls of the cold ash hopper 36 parallel to the center line of the model water-cooled wall. When the flue gas enters from the top, an upper triangular isobaric compartment is set. When the flue gas enters from the bottom, a lower triangular isobaric compartment is set on the two side walls to allow the flue gas to evenly enter the furnace.

[0073] When the high-temperature flue gas generated by the pre-mounted biomass independent combustion boiler is introduced into the furnace from the front and rear walls of the cold ash hopper of the main coal-fired power station boiler, it can enter the furnace parallel to the center line of the membrane water-cooled wall or perpendicular to the center line of the membrane water-cooled wall; when the flue gas enters the furnace from the two side walls, the flue gas inlet is parallel to the center line of the membrane water-cooled wall, and when the flue gas enters from above, an upper triangular isobaric smoke bin is set on the two side walls, and when the flue gas enters from below, a lower triangular isobaric smoke bin is set on the two side walls, so that the flue gas can be evenly introduced into the furnace; when it is necessary to completely decouple the coal-fired system under low load, and only rely on the mixing of high-temperature flue gas after independent combustion of biomass to maintain the long-term safe operation of the main coal-fired power station boiler, this solution can achieve 100% biomass blending and ensure the zero-carbon operation of the coal-fired power boiler with pure biofuel.

[0074] like Figure 9a As shown, the high-temperature flue gas is sent into the furnace in a "W"-shaped cross-mixing flow from the front and rear walls of the flame deflection angle above the separation secondary air duct 16 at a set inclination angle downward; Figure 9b As shown, the high-temperature flue gas is sent into the furnace from the two side walls of the flame deflection angle above the separation secondary air duct 16 at a set inclination angle in a "W"-shaped cross-mixing flow manner. The flue gas is sent into the furnace from the front and rear walls and the two side walls in a "W"-shaped cross-mixing flow manner to enhance the mixing of the high-temperature flue gas generated by coal combustion and the high-temperature flue gas generated by biomass combustion. At the same time, it can be evenly sent into the temperature field of the upper front and rear screen superheaters 19 to reduce the flue gas temperature deviation of the left and right walls of the front and rear screen superheaters 19.

[0075] like Fig.10a and Fig.10b As shown, a through hole is provided on the surface of the flow distributor 20 facing away from the high-temperature flue gas, and 1 to n through holes are arranged along the left and right walls in the space in front of the high-temperature reheater, low-temperature superheater and low-temperature reheater of the main coal-fired power plant boiler, respectively. A high-temperature flue gas inlet header 50 is arranged below the flow distributor 20. The high-temperature flue gas is ejected through the high-temperature air ejector 14, enters the flow distributor 20 from the high-temperature flue gas inlet header 50, and then overflows from the hole on the side of the flow distributor 20 facing away from the high-temperature flue gas in a diffusion manner, and cross-mixes with the flue gas generated by the main coal-fired power plant boiler; as shown Fig.10c , Fig.10d , Fig.10e and Fig.10fAs shown, the flow distributor 20 is arranged in a row or staggered manner in the horizontal pipeline in front of the SCR reactor, and a high-temperature flue gas inlet header 50 is arranged below the flow distributor 20. The flue gas from the front biomass combustion boiler enters the flow distributor 20 from the high-temperature flue gas inlet header 50; the high-temperature flue gas in the flow distributor 20 enters the horizontal pipeline in front of the SCR reactor by relying on the strong negative pressure generated by the blower 35 arranged in the plate air preheater 32 of the main coal-fired power plant boiler, and then cross-mixes with the mainstream flue gas and enters the SCR reactor 28 together to implement denitrification reaction, and then is discharged through the chimney 29 after dust removal and desulfurization.

[0076] In the present invention, the flow equalizer arranged before the high-temperature superheater 21, the high-temperature reheater 22, and the low-temperature superheater 25 is an optional embodiment. When the main coal-fired power station boiler has been provided with measures for adjusting the superheater steam temperature and the reheater steam temperature during low-load operation, there is no need to arrange the flow equalizer 20 before the high-temperature superheater 21 and the high-temperature reheater 22; in addition, when the large-capacity main coal-fired power station boiler has been provided with a turning smoke chamber, and a flue gas regulating baffle is provided in the rear shaft after the turn to adjust the flue gas flow and flue gas temperature between the left and right flue superheaters and reheaters, there is no need to arrange the flow equalizer 20 at the vertical position after the high-temperature reheater 22 or at the horizontal position of the turning smoke chamber outlet; otherwise, it is necessary to set the flow equalizer 20 at these three positions.

[0077] When the main coal-fired power plant boiler is running at low load, the high-temperature flue gas generated by the low-nitrogen combustion of the pre-biomass independent combustion boiler is mixed into the horizontal flue from the high-temperature superheater 21, high-temperature reheater 22, low-temperature superheater 25 and the equal flow distributor 20 arranged before the SCR reactor 28 at the rear of the front and rear screen superheaters 19.

[0078] Flow distributors are arranged in front of the high-temperature superheater, high-temperature reheater, low-temperature superheater and in front of the horizontal pipes in front of the SCR reactor. 1 to n flow distributors are arranged vertically along the left and right side walls. The high-temperature flue gas generated after the low-nitrogen combustion of the front biomass independent combustion boiler flows out from the leeward wall opening in a diffused manner and cross-mixes with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler; the purpose of mixing the high-temperature flue gas in front of the high-temperature superheater, high-temperature reheater and low-temperature superheater is to increase the inlet flue gas temperature entering the high-temperature superheater and high-temperature reheater under low load, which is actually to increase the heat absorption and rated outlet steam temperature of the high-temperature superheater and high-temperature reheater to ensure the power generation efficiency and power generation under low load; especially the flow distributor arranged in front of the SCR reactor should strive to have a uniform temperature field to prevent the denitrification catalyst in the SCR reactor from sintering and losing its catalytic activity due to uneven temperature field.

[0079] It should be noted that the flow distributor 20 arranged before the low-temperature superheater 25 in the figure should be located at a horizontal position at the outlet of the turning smoke chamber, but the low-temperature superheater and low-temperature reheater horizontal tube bundles are arranged in the left and right flues in the tail shaft after the turning of the turning smoke chamber, and the low-temperature superheater and low-temperature reheater horizontal tube bundles are turned 90° upward and suspended on the furnace roof of the turning smoke chamber with the outlet header, making it impossible to arrange a horizontally placed flow distributor in this structure. Therefore, the flow distributor arranged before the low-temperature superheater 25 can actually only be arranged after the high-temperature reheater 22, that is, at the inlet of the turning smoke chamber, which is beneficial for the flue gas flow to diffuse and mix more evenly after passing through the turning smoke chamber.

[0080] refer to Fig.11a and Fig.11b A hinge plate 49 is provided at the through hole of the flow distributor 20 which faces away from the air flow direction; Fig.11a As shown, when the coal-fired power plant boiler is running at low load, the high-temperature flue gas generated by the pre-placed biomass independent combustion boiler is introduced into the high-temperature flue gas inlet header below the equalizing distributor 20. The high-temperature flue gas, through its own pressure head and power, opens the movable hinge plate arranged on the leeward wall of the distributor, and the high-temperature flue gas flows out from the opening and cross-mixes evenly with the mainstream flue gas generated by the combustion of the main coal-fired power plant boiler; Fig.11b As shown, when the coal-fired power boiler is operating normally, the movable hinge plate remains closed under the action of gravity, ensuring that the mainstream flue gas generated by the combustion of the coal-fired power boiler will not flow back into the flow distributor 20, so as to prevent fly ash in the coal-fired flue gas from flowing into the flow distributor and blocking the flow distributor channel. Fig.11a and 11b As shown, a limit rib is set above the hinge plate to prevent the high-temperature flue gas from rushing out of the opening on the leeward wall of the equalizer and opening the hinge plate to an angle greater than 90°, so that it cannot be restored to its original position by gravity. The equalizers and high-temperature flue gas inlet headers and hinge plates arranged at different temperature levels should be made of chromium-molybdenum alloy steel and chromium-nickel stainless steel plates or steel pipes with low alloy content, medium alloy content and high alloy content that can withstand dry burning of flue gas temperatures of 500℃ to 1100℃. The materials should be 15CrMo, 12Cr1MoV, 1Cr6Si2Mo, 1Cr18Ni9Ti, 1Cr25Ni12Si2, 1Cr25Ni14Si2, 1Cr25Ni20Si2 and other materials.

[0081] The high-temperature flue gas ducts between the pre-installed biomass independent combustion boilers and between the pre-installed biomass independent combustion boilers and the main coal-fired power station boilers are detachably connected by flanges. When fly ash or aerosols accumulate inside the high-temperature flue gas ducts after long-term operation, they can be regularly disassembled and cleaned. At the same time, when multiple pre-installed biomass independent combustion boilers are set up, when one or several independent combustion boilers are shut down for maintenance, the high-temperature flue gas regulating dampers set on the corresponding high-temperature flue gas ducts are closed, so that the independent combustion boilers and the high-temperature flue gas ducts can be repaired without affecting the real-time operation of the main coal-fired power station boilers. High-temperature flue gas ducts can be lined with ordinary carbon steel plates or carbon-manganese steel plates with a refractory material of more than 50 mm, and the outside of the steel plate can be laid with a heat-insulating material of more than 30 mm and a thermal insulation material of more than 50 mm. If you want to reduce the weight of the high-temperature flue gas duct lined with refractory materials, and the outer lining of thermal insulation and thermal insulation materials, you can also directly use chromium-molybdenum alloy steel and chromium-nickel stainless steel plates or steel pipes with low alloy content, medium alloy content and high alloy content that can withstand dry burning of flue gas temperatures of 500℃ to 1100℃. The material should be 15CrMo, 12Cr1MoV, 1Cr6Si2Mo, 1Cr18Ni9Ti, 1Cr25Ni12Si2, 1Cr25Ni14Si2, 1Cr25Ni20Si2. Although the lining refractory material is omitted, the outside of the flue The side still needs outer lining insulation and heat preservation materials; secondly, the high temperature tubular air preheater 12 will also produce hot air temperature as high as 900°C to 1000°C due to the high temperature flue gas temperature of 1000°C to 1100°C, and its metal wall temperature can also reach 850°C to 1050°C, and its material is also required to be selected from 0Cr25Ni12Si2, 0Cr25Ni14Si2, 0Cr25Ni20Si2 and other materials; high temperature flue gas regulating baffles (17) are installed in the high temperature flue gas ducts. The high temperature flue gas regulating baffles (17) are required to be selected from 0Cr25Ni12Si2, 0Cr25Ni14Si2, 0Cr25Ni20Si2 materials due to the high temperature flue gas temperature of 1000°C to 1100°C.

[0082] When the high-temperature flue gas generated by the independent combustion of biomass enters the furnace through the high-temperature flue gas pipeline connected to the furnace wall and membrane wall of the main coal-fired power plant boiler, some flat steels 48 in the membrane water-cooled wall tube 47 are removed. When the flue gas flow area meets the needs, the flat steel in the middle of the membrane water-cooled wall tube 47 at the flue gas inlet can be removed to directly pass the flue gas; when the flue gas flow area does not meet the needs, one or more water pipes in the middle of the membrane water-cooled wall tube 47 are cut off and replaced with bent pipes after welding and modification, and one or more water pipes and one or more flat steels are replaced. The flow area occupied by the steel; or a narrow slit is cut by laser on the flat steel 48 in the middle of the membrane water-cooled wall tube 47, and the narrow slits are staggered or arranged in sequence, and the flue gas is ejected from the narrow slit to increase the stiffness of the mixed flue gas jet; or in order to increase the flue gas stiffness when the mixed flue gas is injected into the furnace, the thickness of the flat steel 48 is increased, and then the narrow slit is cut by laser to further increase the depth of the flue gas injected into the furnace, so as to strengthen the mixing degree of the high-temperature flue gas generated after the independent combustion of biomass and the mainstream high-temperature flue gas generated after the combustion of the main coal-fired power plant boiler.

[0083] like Fig.12a As shown in the figure, when the smoke flow area is sufficient, the flat steel at the smoke inlet is removed to directly let in the smoke; Figure 12b As shown, when the flue gas flow area is not enough, the middle water pipe of the water-cooled wall tube 47 is cut off and replaced with a bent pipe, which can free up space for two flat steels; Fig.12c As shown, when the flue gas circulation area is not enough, the water-cooled wall tube 47 can also be pulled up to provide space for the flue gas to enter the main coal-fired power plant boiler, such as Fig.12d and Fig.12e As shown, narrow gaps can be cut on the flat steel by laser. The narrow gaps can be staggered or arranged in sequence. The smoke is emitted from the narrow gaps, which can increase the smoke stiffness. When the flat steel is thin, the flat steel can be thickened before cutting the narrow gaps with laser. This can further increase the distance that the smoke is emitted into the furnace and further increase the smoke stiffness.

[0084] The present invention sends the high-temperature flue gas generated after the low-nitrogen combustion of the front biomass independent combustion boiler directly to the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent heating surfaces at all levels and the mixing port of the tail flue according to the flue gas temperature adjustment requirements, and cross-mixes it evenly with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler, which can achieve 100% mixed biomass low-load or ultra-low load flexibility transformation and long-term safe operation. After the high-temperature flue gas of the front biomass independent combustion is mixed with the mainstream flue gas generated by the combustion of the main coal-fired power station boiler, the SCR denitrification reactor, dust collector and FGD desulfurization tower arranged in the tail flue of the main coal-fired power station boiler respectively complete the denitrification, dust removal and desulfurization requirements, thereby completing the ultra-low emission of the main coal-fired power station boiler and then being discharged into the atmosphere from the chimney, while the front biomass independent combustion boiler only generates high-temperature flue gas to transport the main coal-fired power station boiler, and does not need to be independently configured with flue gas purification equipment. The pre-placed biomass independent combustion boiler and the main coal-fired power station boiler realize independent combustion of different fuels, multi-stage blending, organic combination, and mutual complementation, and jointly realize the low-carbon and zero-carbon technical transformation of coal-fired power units. In addition to being used for coal-fired pulverized coal combustion boilers, atmospheric pressure fluidized bed combustion boilers that burn granular or lumpy coal particles, and pure condensing power generation units of main coal-fired power station boilers of other fossil fuels, the present invention is also suitable for any cogeneration boiler unit, and is also suitable for any industrial steam boiler and hot water boiler for centralized heating that burns fossil fuels.

[0085] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for independently burning biomass and co-combining coal-fired power plant boilers, characterized in that: The flue gas generated by the independent combustion of biomass is sent to the mixing ports of the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the subsequent levels of heating surface-covered flues and the tail flow flue through the high-temperature flue gas duct according to the set mixing ratio, and is mixed with the mainstream flue gas after combustion in the main coal-fired power station boiler and enters the SCR together to complete flue gas denitrification and subsequent purification treatment before being discharged into the atmosphere. The mixing ports are opened in the lower, middle and upper areas of the furnace of the main coal-fired power station boiler and the membrane water-cooled wall pipe-laid furnace wall covering the various levels of heating surfaces downstream of the furnace and the steel furnace wall of the tail flow flue.

2. The method of independently burning biomass and co-blending coal-fired power station boiler according to claim 1, characterized in that: After heat exchange with high-temperature flue gas, air becomes high-temperature air, and the high-temperature air is used to guide the flue gas generated by independent combustion of biomass; or the pressurized flue gas generated by independent combustion of biomass is directly sent to the mixing port; or the flue gas generated by independent combustion of biomass is pressurized and sent to the mixing port to overcome the system flow resistance of high-temperature flue gas mixed with the main coal-fired power station boiler.

3. The method of independently burning biomass and co-blending coal-fired power station boiler according to claim 1, characterized in that: The biomass is pyrolyzed in advance, and the high-temperature flue gas produced after the direct combustion of the pyrolysis gas is sent to the flue gas mixing ports of various levels of the main coal-fired power station boiler through the high-temperature flue gas pipeline; the biomass is gasified in advance, and the high-temperature flue gas produced after the direct combustion of the gasification gas is sent to the flue gas mixing ports of various levels of the coal-fired power station boiler through the high-temperature flue gas pipeline.

4. The method of independently burning biomass and co-combining coal-fired power plant boilers according to claim 1, characterized in that: According to the particle size of the supplied biomass raw materials, they are sorted and fixed-bed layered combustion boilers, moving bed layered combustion boilers or normal-pressure fluidized bed combustion boilers or pyrolysis furnaces or gasification furnaces are selected respectively. The larger biomass raw materials are sent to the moving bed layered combustion boiler for combustion; the smaller biomass raw materials are sent to the fixed bed layered combustion boiler or normal-pressure fluidized bed combustion boiler for combustion; when there is domestic sludge to be treated at the location of the main coal-fired power station boiler, the sludge with a moisture content of 35% to 40% after drying by other thermal energy is directly sent to the normal-pressure fluidized bed combustion boiler for direct combustion, and the high-temperature flue gas generated by it is sent to the mixing port of the main coal-fired power station boiler.

5. The method of independently burning biomass and co-blending coal-fired power station boiler according to claim 1, characterized in that: The high-temperature flue gas generated after the independent combustion of biomass is purified by the primary flue gas separation and then sent to the high-temperature flue gas pipeline to be transported to the main coal-fired power plant boiler for mixing, or before separation, flocculants are sprayed into the flue gas after combustion to promote the coagulation of fly ash and aerosol particles and remove them.

6. A device for independently burning biomass and co-mixing coal-fired power station boilers, characterized in that: It includes a pre-mounted biomass independent combustion boiler and a main coal-fired power station boiler. The main coal-fired power station boiler has mixing ports in the lower, middle and upper areas of the furnace and the flue covered with heating surfaces at all levels downstream of the furnace and the tail flow flue. The flue gas outlet of the biomass independent combustion boiler is connected to the mixing port. A high-temperature flue gas regulating damper with adjustable opening is arranged on the flue gas pipeline connecting the flue gas outlet of the biomass independent combustion boiler to the mixing port. The pre-mounted biomass independent combustion boiler adopts one of the following boiler systems: ① one or more fixed-bed layered combustion boilers A for independent combustion of biomass, ② one or more fixed-bed layered combustion boilers A for independent combustion of biomass Moving bed layered combustion boiler B, ③ one or more atmospheric fluidized bed combustion boilers C that independently burn biomass, ④ one or more fixed bed layered combustion boilers A and a combined boiler system of moving bed layered combustion boiler B and atmospheric fluidized bed combustion boiler C, ⑤ one or more pressurized circulating fluidized bed boilers, ⑥ one or more moving bed layered combustion boilers B or atmospheric fluidized bed combustion boilers C, combined with one or more biomass pyrolysis furnaces or biomass gasification furnaces; the aforementioned pre-biomass independent combustion boilers are all low-nitrogen combustion biomass independent combustion boilers based on the coupling of air staging, fuel staging and flue gas recirculation.

7. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 6, characterized in that: The air required for combustion of the pre-biomass independent combustion boiler is all from the secondary hot air at the outlet of the air preheater at the rear of the main coal-fired boiler. An air preheating interlayer (55) is arranged in the furnace wall of the pre-biomass independent combustion boiler. The cold air is preheated by the inner supporting steel plate (54) in the air preheating interlayer (55) and then sent into or sucked into the blower inlet. The cold air at the blower inlet is mixed to increase the inlet temperature of the cold end of the air preheater, which is used to increase the metal wall temperature of the cold end of the air preheater to inhibit the low-temperature corrosion of the air preheater. At the same time, it assists the long-term safe operation of the pre-biomass independent combustion boiler and the main coal-fired power station boiler in air synergistic mixing. The furnace wall structure of the pre-biomass independent combustion boiler It is arranged to have six layers, from the inner side of the high-temperature flue gas to the air side outside the furnace wall, respectively: refractory material (52), heat-insulating material layer (53), inner supporting steel plate (54), air preheating interlayer (55), outer supporting steel plate (56), and insulation layer (57), wherein the inner supporting steel plate is welded with grabbing nails (51) for fixing the refractory material. The grate in the fixed bed layered combustion boiler described in the pre-biomass independent combustion boiler is a fixed grate or a fixed bed rotating grate; the grate (4) in the moving bed layered combustion boiler is a chain moving grate, a reciprocating moving grate or a water-cooled vibrating grate; the atmospheric pressure fluidized bed combustion boiler adopts a boiling fluidized bed combustion boiler, an internal circulation fluidized bed combustion boiler or an external circulation fluidized bed combustion boiler.

8. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 7, characterized in that: A high-temperature and high-pressure induced draft fan (42) is arranged on the flue gas pipeline from the flue gas outlet of the pre-placed biomass independent combustion boiler to the mixing port of the main coal-fired power station boiler to overcome the system flow resistance of the high-temperature flue gas mixing with the main coal-fired power station boiler.

9. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 6, characterized in that: The flue gas outlet of at least one front biomass combustion boiler is connected to the flue gas inlet of a high-temperature tubular air preheater (12), the flue gas outlet of the high-temperature tubular air preheater (12) is connected to the horizontal pipeline in front of the inlet of the SCR reactor (28) of the main coal-fired power plant boiler, the high-temperature air outlet of the high-temperature tubular air preheater (12) is provided with a high-temperature air outlet header (13), the high-temperature air outlet header (13) is connected to a high-temperature air ejector (14), the air inlet of the high-temperature tubular air preheater (12) is connected to the air preheater; the flue gas pipeline where the high-temperature air ejector (14) is located is connected to a mixing port.

10. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 9, characterized in that: The flue gas outlet of the furnace of the fixed-bed layered combustion boiler A or the moving-bed layered combustion boiler B is connected to a horizontal cyclone separator (10), a flocculant injection device (11) is arranged in front of the horizontal cyclone separator (10), the particle outlet of the horizontal cyclone separator (10) is connected to the furnace through a material leg (9), and the flue gas outlet of the horizontal cyclone separator (10) is connected to the flue gas inlet of a high-temperature tubular air preheater (12); or the horizontal cyclone separator (10) at the flue gas outlet of the furnace of the fixed-bed layered combustion boiler A or the moving-bed layered combustion boiler B is replaced with 1 to n inwardly extending rotating bosses (37), and the high-temperature flue gas generated in the fixed-bed layered combustion boiler A or the moving-bed layered combustion boiler B is passed to the horizontal cyclone separator (10) and the flue gas inlet of the high-temperature tubular air preheater (12) is connected to the horizontal cyclone separator (10). After passing through 1 to n rotating bosses, the flue gas is merged into the total high-temperature flue gas pipeline and connected to the mixing port on the main coal-fired power plant boiler; the flue gas outlet of the furnace of the fluidized bed combustion boiler C is connected to the cyclone separator (41), a flocculant injection device (11) is arranged in front of the flue gas inlet of the cyclone separator (41), the flue gas outlet of the cyclone separator (41) is connected to the mixing port on the main coal-fired power plant boiler through the high-temperature flue gas pipeline, the high-temperature flue gas pipeline is connected to the high-temperature air ejector (14), and the high-temperature air ejector (14) is connected to the high-temperature air outlet header (13); the particle outlet of the cyclone separator (41) is connected to the return device (39) through the vertical pipe (40), and the return device (39) is connected to the furnace.

11. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 6, characterized in that: A flow distributor (20) is arranged above the furnace of a main coal-fired power station boiler and in the flue gas duct in front of an SCR reactor inlet, or the flow distributor (20) is arranged only in the flue gas duct in front of the SCR reactor inlet; the cross section of the flow distributor (20) is a rhombus, a rectangle, or a combination of a rectangle and a triangle; a through hole is provided on a side of the flow distributor (20) that is away from the airflow direction, and a hinge plate (49) is provided at the through hole; a limiting rib (58) is provided on the hinge plate (49) to prevent the hinge plate (49) from being unable to reset after turning upward by more than 90 degrees under the impact of the airflow; 1 to n flow distributors are arranged in series or staggered; the bottom of the flow distributor (20) is connected to a high-temperature flue gas inlet header (50); when the flow distributor (20) is arranged above the furnace of the main coal-fired power station boiler, the flow distributor (20) is arranged vertically along the left and right side walls.

12. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 6, characterized in that: When the high-temperature flue gas generated by the independent combustion of biomass is connected to the furnace wall and membrane wall of the main coal-fired power plant boiler through the high-temperature flue gas pipeline and sent into the furnace, when the mixed flue gas flow rate is small, a rectangular slit is cut on the flat steel (48) in the middle of the membrane water-cooled wall tube (47), and the slits are arranged in a staggered or straight line; or the thickness of the flat steel (48) is increased to improve the flue gas jet stiffness, and the rectangular slit is cut; when the mixed flue gas flow rate is large and the rectangular slit flow area does not meet the requirements, part of the flat steel (48) in the membrane water-cooled wall tube (47) is removed, or the flat steel in the middle of the membrane water-cooled wall tube (47) at the flue gas inlet is removed to directly pass the flue gas; When the mixed flue gas flow rate increases further, one or more water pipes in the middle of the membrane water-cooled wall tube (47) are cut off to replace the flow area occupied by one or more water pipes and one or more flat steels.

13. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 6, characterized in that: When the pre-mounted biomass combustion boiler adopts a pressurized fluidized bed combustion boiler, a vertical cyclone separator (41) is arranged at the flue gas outlet of the furnace of the pressurized fluidized bed combustion boiler. The cyclone separator (41) is arranged inside the pressure shell (44), and the flue gas outlet of the vertical cyclone separator (41) is connected to the mixing port.

14. The device for independently burning biomass and co-blending coal-fired power station boiler according to claim 6, characterized in that: When the high-temperature flue gas generated by the low-nitrogen combustion of the pre-installed biomass independent combustion boiler is introduced into the furnace from the front and rear walls of the cold ash hopper (36) of the main coal-fired power station boiler, it enters the furnace parallel to the center line of the membrane water-cooled wall or perpendicular to the center line of the membrane water-cooled wall; when the flue gas enters the furnace from the two side walls, the flue gas inlet is parallel to the center line of the membrane water-cooled wall, and when the flue gas enters from the top, an upper triangular isobaric smoke bin is set on the two side walls, and when the flue gas enters from the bottom, a lower triangular isobaric smoke bin is set on the two side walls. When the coal powder preparation and coal powder combustion systems are completely disconnected and the high-temperature flue gas generated by the biomass combustion equipment 100% independently supports the long-term safe operation of the main coal-fired power station boiler according to the set load ratio, in order to fully utilize all the radiation heating surfaces of the main coal-fired boiler, the high-temperature flue gas generated by the low-nitrogen combustion of the pre-installed biomass independent combustion boiler is preferentially introduced from the front and rear walls and the two side walls of the cold ash hopper (36) of the main coal-fired power station boiler.

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