W-flame ultra-supercritical boiler for burning anthracite and operation control method

Abstract

The invention discloses a W-flame ultra-supercritical boiler for burning anthracite and an operation control method, and belongs to the technical field of design and manufacturing of power station boilers. The boiler comprises a combustion system, an air distribution system, a fuel supply system and a steam-water system, the combustion system comprises a hearth and a plurality of combustors, the air distribution system comprises staged air, over fire air, a close-to-wall air nozzle and a close-to-wall air parallel side water cooling wall, the fuel supply system comprises a primary air pipeline and an exhaust pipeline for feeding exhaust in a split mode, and the steam-water system comprises a water cooling wall and a reheater. The water cooling wall is provided with a middle mixing header, the reheater comprises a low-temperature section and a high-temperature section, an accident spray desuperheater is arranged at an inlet and an outlet of the low-temperature reheater, and a cross mixing header is arranged at an outlet. The invention is mainly used for high-efficiency clean combustion power generation of high-sulfur and low-volatile anthracite, and is used for coal-fired power generation of 660MW grade power stations.

Description

Technical Field

[0001] This invention relates to the field of power plant boiler design and manufacturing technology. More specifically, this invention relates to a W-flame ultra-supercritical boiler for burning anthracite coal and its operation control method. Background Technology

[0002] Southwest China possesses abundant anthracite coal reserves. This type of coal is characterized by low volatile matter content, difficulty in ignition, and slow combustion. W-flame boilers are commonly used in thermal power generation to ensure effective ignition and combustion, thereby improving boiler efficiency. To further enhance power generation efficiency and reduce carbon emissions, it is necessary to upgrade the boiler's steam parameters from subcritical or supercritical levels to even higher ultra-supercritical parameters. This project targets typical high-sulfur, low-volatile anthracite coal in Guizhou Province, with a dry ash-free basis of 9.28% volatile matter, 31.08% ash, and 2.85% sulfur. Due to limitations in hydrodynamic safety and the high-temperature corrosion caused by high-sulfur coal, the highest parameters of the currently operational W-flame supercritical boilers are only 26.15 MPa.g / 585℃ / 583℃ (main steam pressure / main steam temperature / reheat steam outlet temperature), which are also supercritical parameters. Furthermore, significant technical shortcomings exist: First, the stable combustion capability is weak, making it difficult to maintain stable combustion at low loads, typically only reaching 40% load. Second, during combustion, high-sulfur coal easily forms a reducing atmosphere in the near-wall region of the furnace, leading to severe high-temperature sulfur corrosion of the water-cooled walls. Third, anthracite itself is difficult to ignite and has a low burnout rate, making it difficult for traditional burners to simultaneously meet the requirements of stable combustion and low nitrogen emissions, resulting in high NOx emissions. Finally, the reheater tube bundles are prone to scale blockage due to excessive tube length and large thermal deviation. Therefore, there is an urgent need for a clean, low-carbon, safe, and efficient W-flame ultra-supercritical boiler to respond to the dual carbon targets and the requirements of the new generation of coal-fired power technology, and to further improve boiler parameters to the ultra-supercritical level. Summary of the Invention

[0003] This invention provides a W-flame ultra-supercritical boiler for burning anthracite, which can improve the safety, stability and adaptability of the boiler under full load operation. Through the collaborative and innovative design of the furnace, combustion, air distribution and steam-water system, it effectively solves the coupled problems of hydrodynamic safety under high parameters, high-temperature corrosion of high-sulfur coal and stable combustion of anthracite under low load, enabling the boiler to break through the parameter bottleneck and achieve efficient, clean and flexible operation.

[0004] This invention provides an operation control method for an ultra-supercritical W-flame boiler burning anthracite. By synergistically regulating key processes such as high-concentration stable combustion, zoned mass flow rate, and wall oxidizing atmosphere, the advantages of the boiler's hardware design are systematically transformed into excellent operating performance. This ensures high parameters, high efficiency, and low emissions while guaranteeing hydrodynamic safety and long-term reliability of the heating surface.

[0005] To achieve these objectives and other advantages according to the present invention, a W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite is provided, comprising: A combustion system includes a furnace and multiple burners disposed on the front and rear walls of the furnace. The furnace includes a lower furnace and an upper furnace. The height of the lower furnace accounts for 50-54% of the total height of the furnace. The primary air nozzle of the burner is provided with a blunt body at its end. The air distribution system includes a staged air nozzle and a burnout air nozzle for supplying combustion air into the furnace, and a wall-mounted air nozzle for supplying air to the side wall of the furnace. The burnout air nozzle and the burner are arranged at intervals in the horizontal direction, and the air outlet direction of the wall-mounted air nozzle is set to be parallel or approximately parallel to the side water-cooled wall. A fuel supply system includes a primary air duct for supplying pulverized coal to the burner, and a waste gas duct for delivering the oxygen-deficient pulverized coal gas stream as waste gas into the furnace through a waste gas nozzle independent of the burner, the waste gas duct being configured to deliver the waste gas in at least two streams at different heights in the furnace. The steam-water system includes a water-cooled wall arranged in the furnace and a reheater for heating steam. The water-cooled wall is connected to an intermediate mixing header for mixing the working fluid at a height between the lower and upper furnace. The reheater includes a low-temperature reheater and a high-temperature reheater. The outlet of the low-temperature reheater is connected to a cross-mixing header for cross-mixing steam flows from the left and right sides of the furnace. Both the inlet and outlet of the low-temperature reheater are equipped with emergency water spray desuperheaters.

[0006] Preferably, the burner is a dual-adjustable swirl burner, and the bluff body is made of a silicon carbide and silicon nitride composite material with a streamlined cross-section to form a stable recirculation zone downstream of the primary air nozzle.

[0007] Preferably, the water-cooled walls of the steam-water system employ heat exchange tubes with differentiated configurations for different zones, and the boiler is equipped with enclosing water-cooled walls; the heat exchange tubes of the water-cooled walls are configured according to the furnace area as follows: The lower furnace wing wall area uses heat exchange tubes with an outer diameter of 32mm, a wall thickness of 6mm, and a pitch of 63mm; The lower furnace lining, excluding the wing walls, uses heat exchange tubes with an outer diameter of 32mm, a wall thickness of 5.3mm, and a pitch of 53mm. The cold ash hopper area in the lower furnace uses heat exchange tubes with an outer diameter of 32mm and a wall thickness of 5.8mm; The main area of ​​the upper furnace chamber uses heat exchange tubes with an outer diameter of 28mm and a wall thickness of 6mm; The four corner areas of the upper furnace chamber use heat exchange tubes with an outer diameter of 28mm and a wall thickness of 6.5mm; The area 500mm above the tip of the flame deflector in the upper furnace uses heat exchange tubes with an outer diameter of 28mm and a wall thickness of 5.5mm. The heat exchange tubes with an outer diameter of 76mm and a wall thickness of 14mm are selected for the front screen tubes in the water-cooled wall area after the furnace is installed. The water-cooled wall of the upper furnace lining uses heat exchange tubes with an outer diameter of 28mm and a wall thickness of 5.5mm.

[0008] Preferably, the downcomer supplying water to the water-cooled wall is provided with a throttling orifice plate at its end, and the orifice diameter of the throttling orifice corresponding to the water-cooled wall circuit of the front and rear walls of the furnace is one or more combinations of 36mm, 38mm, 47.5mm or 54mm, and the orifice diameter of the throttling orifice corresponding to the water-cooled wall circuit of the side wall of the furnace is in the range of 42mm to 47mm. The number of working fluid outlet pipes for each loop of the lower furnace non-wing wall water-cooled wall is 2, and the number of connecting pipes between the upper furnace rear wall water-cooled wall and the lower header of the front screen superheater is 17.

[0009] Preferably, in the air distribution system, the burnout air nozzles are respectively installed on the front and rear walls of the furnace, and the wall-mounted air nozzles are arranged on the left and right walls of the furnace and are divided into multiple layers in the vertical direction, with the air supply volume of each layer of wall-mounted air nozzles being independently adjustable. The air distribution system also includes wing wall cooling air nozzles arranged at the four corners of the furnace.

[0010] Preferably, the exhaust gas pipeline includes a lower exhaust gas branch pipe and an upper exhaust gas branch pipe, and the corresponding exhaust gas nozzles include a lower exhaust gas nozzle and an upper exhaust gas nozzle. The lower exhaust gas nozzle is located between the burner outlet and the nearest downstream staged air nozzle, and the upper exhaust gas nozzle is located between the burner outlet and the burnout air nozzle.

[0011] Preferably, the high-temperature reheater is composed of multiple tube panels, each of which is a U-shaped structure formed by bending one or more parallel heat exchange tubes in a 180° turn, and the heat exchange tubes of the high-temperature reheater are made of austenitic stainless steel that is resistant to high-temperature steam oxidation.

[0012] Preferably, it also includes a flame-retardant strip covering part of the outer surface of the water-cooled wall, the flame-retardant strip being continuously distributed on the front and rear walls of the furnace, discontinuously distributed in blocks on the left and right walls of the furnace, and the flame-retardant strip not being arranged in the area below the inflection point of the furnace cold ash hopper.

[0013] The method for operating and controlling a W-flame ultra-supercritical boiler burning high-sulfur, low-volatile anthracite coal, wherein the furnace meets the following heat load parameters: total furnace volumetric heat load not less than 90 kW / m³. 3 The volumetric heat load of the area under the arch shall not be less than 220 kW / m². 3The heat load on the arch section shall not be less than 5.5 MW / m 2 The heat load at the arch cross section shall not be less than 3.0 MW / m. 2 The method includes the following steps: [The system is equipped with a gas ignition device designed to handle a total input heat of 15-20% of the boiler's maximum continuous evaporation capacity.] Combustion organization steps: Maintain a high coal powder concentration environment in the primary air duct of the burner, achieve 1.15~1.5kg coal powder / / kg primary air through rich-lean separation, and control the exhaust gas to be divided into at least two streams and sent into the furnace from different height positions; Hydrodynamic control steps: Control the working fluid mass flow velocity through the water-cooled wall in the lower furnace region to be no less than 1150 kg / (m³). 2 •s), and control the mass flow rate of the working fluid flowing through the water-cooled wall of the upper furnace region to be between 1750 and 1850 kg / (m³). 2 Between ·s); Wall atmosphere control steps: By adjusting the airflow along the wall, the oxygen concentration near the water-cooled wall surface is maintained at above 2%.

[0014] A 660MW-class coal-fired power plant generating unit includes the aforementioned W-flame ultra-supercritical boiler used for burning high-sulfur, low-volatile anthracite. The boiler's ultra-supercritical parameters are: main steam pressure not less than 29.3 MPa.g, main steam temperature not less than 605℃, and reheat steam outlet temperature not less than 623℃.

[0015] The present invention has at least the following beneficial effects: First, this invention ensures stable hydrodynamics under full load conditions by optimizing the furnace ratio, configuring water-cooled walls in zones, balancing flow distribution, and improving the reheater structure. This avoids problems such as heat transfer deterioration, high-temperature corrosion, and coking, thereby improving boiler operating safety and extending equipment service life.

[0016] Secondly, by employing a burner with a composite blister, implementing stratified exhaust gas delivery, and configuring a large-capacity gas ignition device, this invention synergistically enhances the boiler's low-load stable combustion capability, enabling it to achieve stable combustion at 30% BRL load without oil injection when burning low-volatile anthracite, thus fully meeting the operational requirements of deep peak shaving in the power grid.

[0017] Third, this invention effectively suppresses the initial formation of nitrogen oxides by deeply staged combustion of fuel and air, optimizing air distribution uniformity, and finely organizing the combustion process, while improving the pulverized coal burnout rate. Under the premise of ensuring environmental protection indicators, it reduces coal consumption and carbon emissions for power generation, achieving synergy between environmental protection and energy conservation.

[0018] Fourth, through the coordinated design and optimization of combustion, air distribution, steam and water systems, this invention enables the boiler to fully adapt to the combustion characteristics of high-sulfur, low-volatile anthracite, and specifically solves the technical problems of difficult ignition, low burnout rate, and severe high-temperature corrosion of this type of coal, thus realizing its efficient and clean large-scale utilization.

[0019] Fifth, the 660MW-class generator set of the present invention, by integrating the aforementioned ultra-supercritical parameter boiler, significantly improves the overall power generation efficiency, which not only conforms to the national clean and low-carbon energy policy orientation, but also better adapts to the strict requirements of the new power system for power supply reliability and rapid peak-shaving capability.

[0020] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a W-flame ultra-supercritical boiler according to one technical solution of the present invention; Figure 2 This is a schematic diagram of an air distribution system according to one technical solution of the present invention; Figure 3 This is a schematic diagram of the structure of a burner according to one technical solution of the present invention; Figure 4 This is a schematic diagram of a water-cooled wall partition according to a technical solution of the present invention; Figure 5 This is a schematic diagram of the reheater structure according to one technical solution of the present invention; Figure 6 This is a schematic diagram of a water-cooled wall combustion belt according to one technical solution of the present invention.

[0022] 1-Lower furnace; 2-Upper furnace; 3-Burner; 4-Upper exhaust gas branch pipe; 5-Lower exhaust gas branch pipe; 6-Stage air branch pipe; 7-Flame exhaust air nozzle; 8-Secondary air box; 9-Stage air box; 10-Wing wall air box; 11-Wall-attached air nozzle; 12-Steam-water separator; 13-Low-temperature superheater; 14-Screen-type superheater; 15-Rear screen superheater; 16-Final stage superheater; 17-Low-temperature reheater; 18-High-temperature reheater; 19-Economizer; 2 0-Superheater side flue gas regulating baffle; 21-Reheater side flue gas regulating baffle; 22-Denitrification device; 23-Rotary air preheater; 24-Three-dimensional finned tube preheater; 25-Intermediate mixing header; 26-Blunt body; 27-Primary air duct; 28-Inner secondary air duct; 29-Outer secondary air duct; 30-Inner secondary air blade adjusting rod; 31-Outer secondary air blade adjusting rod; 32-Separation device; 33-Concentration device; 34-Eccentric reducer Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0024] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0025] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the reagents and materials mentioned are commercially available. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to fixed connection or setting, detachable connection or setting, or integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0026] When existing W-flame boilers are used with high-sulfur, low-volatile anthracite, problems such as unstable hydrodynamics, poor combustion stability, high risk of high-temperature corrosion, and large reheater thermal deviations exist. Figure 1-2 As shown, the present invention provides a W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal, comprising: The combustion system includes a furnace and multiple burners 3 disposed on the front and rear walls of the furnace. The furnace is the space where combustion occurs. The furnace includes a lower furnace 1 and an upper furnace 2. The height of the lower furnace 1 accounts for less than 55% of the total height of the furnace. Specifically, the height of the lower furnace accounts for 50-54% of the total height of the furnace. Preferably, the dividing line between the upper and lower furnace 1 is lowered so that the proportion of the lower furnace 1 to the total height of the furnace is adjusted to 51%-52%, which improves the anti-interference ability of the lower furnace 1 and optimizes the hydrodynamic stability. The burners 3 are configured according to the boiler capacity. For example, a total of 24 burners 3 are arranged in pairs on the front and rear walls of the furnace. Specifically, the burners 3 can be HPAX-EX dual-adjustable swirl burners 3. The primary air nozzle end of the burner 3 is provided with a blunt body 26. The blunt body 26 is connected to the nozzle by bolts or welding to ensure structural stability, promote the formation of a reflux zone in the pulverized coal airflow, and enhance ignition stability. The air distribution system includes staged air nozzles and burnout air nozzles 7 for supplying combustion air into the furnace, and wall-mounted air nozzles 11 for supplying air to the side wall of the furnace. The staged air nozzles are connected to the staged air box 9 through staged air branch pipes 6. The staged air nozzles are used to supply an appropriate amount of air to the main combustion zone. The burnout air nozzles 7 and the burners 3 are arranged at intervals in the horizontal direction, that is, they are staggered in the horizontal projection. The spacing is set according to the furnace size and the arrangement density of the burners 3. For example, 15 burnout air nozzles 7 are set on the front and rear walls of the furnace to ensure that the burnout air evenly covers the cross section of the furnace. The air outlet direction of the wall-mounted air nozzles 11 is designed to be parallel or approximately parallel (angle with the wall ≤10°) to the side water-cooled wall to form a wall-mounted air film. The fuel supply system can adopt a medium-speed mill direct-fired pulverizing system. The pulverized coal gas flow from the pulverizing system is divided into two pulverized coal gas flows after passing through the separation device 32 and the concentration device 33 at the inlet of the burner 3. One is primary air carrying high concentration of pulverized coal, which is sent through the center of the burner 3. The other is a light phase exhaust gas separated from the separation device 32 and the concentration device 33, containing a small amount of pulverized coal and primary air. It includes a primary air pipeline for supplying pulverized coal to the burner 3, and an exhaust gas pipeline for sending the light phase pulverized coal gas flow as exhaust gas into the furnace through an exhaust gas nozzle independent of the burner 3. The exhaust gas pipeline is configured to send the exhaust gas into the furnace in at least two streams at different heights. For example, a total of 24 exhaust gas streams are divided into 12 streams and sent into the furnace in two streams. The design of sending exhaust gas in two streams promotes complete combustion of fuel. The steam-water system includes water-cooled walls arranged within the furnace and a reheater for heating steam. It also includes conventionally configured superheaters, economizers 19, and steam-water separators 12. The superheaters include a low-temperature superheater 13, a screen-type superheater 14, a rear screen superheater 15, and a final-stage superheater 16 arranged sequentially. The working fluid flowing within the water-cooled walls absorbs heat from the furnace. An intermediate mixing header 25 for mixing the working fluid is connected to the water-cooled walls at a height between the lower furnace 1 and the upper furnace 2. The water-cooled walls, serving as the main radiant heating surface, cover the entire inner wall of the furnace and can employ a membrane-type water-cooled wall structure. The working fluid flows through the water-cooled walls of the lower furnace 1 and enters the intermediate mixing header 25, where it is mixed before flowing back into the water-cooled walls of the upper furnace 2, eliminating temperature and flow deviations caused by the lower furnace 1. The reheaters include a low-temperature reheater 17 and a high-temperature reheater 18. The low-temperature reheater 17 is arranged in the tail flue, and the high-temperature reheater 18 is arranged in the high-temperature zone at the top of the furnace. The outlet of the low-temperature reheater 17 is connected to a cross-mixing header for cross-mixing the steam flows from the left and right sides of the furnace. The steam flows from the left and right sides of the furnace are fully mixed in the header before entering the high-temperature reheater 18, effectively eliminating thermal deviation. Both the inlet and outlet of the low-temperature reheater 17 are equipped with emergency water spray desuperheaters, preferably a pair for each, for dynamically adjusting the reheat steam temperature deviation. The superheater-side flue gas regulating baffle 20 and the reheater-side flue gas regulating baffle are arranged in the split flue before the economizer 19 in the tail shaft. By adjusting the opening of the superheater-side flue gas regulating baffle 20 and the reheater-side flue gas regulating baffle, the ratio of flue gas flow through the superheater and reheater flue can be changed, thereby precisely controlling the reheat steam temperature.

[0027] The flow path of the high-temperature flue gas is as follows: the high-temperature flue gas generated by the combustion of pulverized coal in the furnace first flows upward through the screen-type superheater 14 and the high-temperature reheater 18 in sequence; then the flue gas turns into the horizontal flue and flows through the low-temperature superheater 13 and the low-temperature reheater 17; then the flue gas flows downward into the tail shaft to heat the economizer 19; finally, the flue gas is purified and waste heat is recovered by the denitrification device 22, the rotary air preheater 23 and the three-dimensional finned tube preheater 24, and then it is sent into the chimney by the induced draft fan for discharge.

[0028] The flow path of the working fluid (water / steam) is divided into a main loop and a reheat loop: In the main loop, the feedwater is preheated by the economizer 19 and then enters the furnace water-cooled wall to absorb radiant heat. After becoming steam, it flows through multiple superheaters and finally becomes ultra-supercritical main steam, which is sent to the high-pressure cylinder of the turbine. In the reheat loop, the steam discharged from the high-pressure cylinder returns to the boiler and is reheated by passing through the low-temperature reheater 17 and the high-temperature reheater 18. After becoming high-temperature reheat steam, it is sent to the intermediate and low-pressure cylinders of the turbine to continue to do work.

[0029] When the boiler is started, the primary air duct of the fuel supply system delivers a high-concentration pulverized coal gas flow to the burner 3 equipped with a silicon carbide and silicon nitride composite bluff body 26. After the burner 3 is ignited, the pulverized coal is injected downwards into the lower furnace 1 and impacts the cold ash hopper, then bounces back upwards, forming a stable W-shaped flame path. The bluff body 26 creates a high-temperature recirculation zone at the nozzle, effectively reducing the ignition heat requirement of the pulverized coal and promoting stable ignition. The air distribution system coordinates with the combustion process, and the staged air nozzles deliver the air required for combustion to ensure the initial mixing of pulverized coal and oxygen. The burnout air nozzles 7 are horizontally spaced from the burner 3. The system provides sufficient oxygen to the upper part of the flame to ensure complete combustion of pulverized coal. The wall-mounted air nozzle 11 sprays airflow parallel to the side water-cooled wall, forming a protective gas film to block corrosive gases from contacting the pipe wall and inhibit high-temperature sulfur corrosion. At the same time, the light-phase pulverized coal airflow separated by the separation device 32 and the concentration device 33 at the inlet of the burner 3 is divided into two streams and fed into the furnace from different heights through the exhaust gas pipeline. They are respectively sent between the outlet of the burner 3 and the staged air nozzle, and between the outlet of the burner 3 and the burnout air nozzle 7, to achieve deep fuel grading and further inhibit the generation of nitrogen oxides.

[0030] The steam-water system efficiently completes heat absorption and steam heating. The working fluid absorbs the heat generated by combustion in the furnace within the water-cooled wall. The working fluid from each loop of furnace 1 under high heat load, which may have temperature and flow deviations, is collected in the intermediate mixing header 25 and the deviations are eliminated after thorough mixing. It then enters the upper furnace 2 for further heating. The steam then enters the reheater system, where it is first preheated by the low-temperature reheater 17. The steam on the left and right sides is cross-mixed in the cross mixing header to eliminate the thermal deviation caused by the uneven flue gas temperature on the left and right sides of the furnace. The abnormal steam temperature is then dynamically regulated by the emergency water spray desuperheater before entering the high-temperature reheater 18 for final heating. The main steam heated to the set temperature is delivered to the high-pressure cylinder of the turbine to perform work. The working fluid after performing work in the high-pressure cylinder is then delivered back to the reheater to participate in the reheating process. The reheated steam is then sent to the intermediate-pressure cylinder of the turbine to continue expanding and performing work.

[0031] In the above technical solution, by integrating the combustion system, air distribution system, fuel supply system and steam-water system, and optimizing the furnace ratio, burner configuration, air distribution method and steam-water circulation path, the boiler can simultaneously take into account combustion stability, power generation efficiency, environmental emissions, hydrodynamic safety and service life of heating surfaces when burning high-sulfur, low-volatile anthracite and bearing ultra-supercritical steam parameters, thus ensuring stable, efficient and safe operation under full load conditions.

[0032] In another technical solution, the burner 3 is a dual-adjustable swirl burner, such as... Figure 3As shown, the HPAX-EX type dual-adjustable air swirl burner is a burner 3 that adjusts the air swirl intensity through inner and outer air adjustment mechanisms. The burner 3 includes a primary air channel 27, an inner secondary air channel 28, an outer secondary air channel 29, a separation device 32, and a concentration device 33. The separation device 32 and concentration device 33 concentrate and separate the pulverized coal airflow from the pulverizing system. The separated dense pulverized coal airflow enters the furnace through the primary air channel 27, while the light pulverized coal airflow forms exhaust gas, which enters the furnace through the upper exhaust gas branch pipe 4 and the lower exhaust gas branch pipe 5. The primary air channel 27 is used to transport the concentrated pulverized coal airflow. The inner secondary air channel 28 and the outer secondary air channel 29 respectively transport combustion air in different proportions and are connected to the secondary air box 8. Figure 3 As shown in b, the primary air-coal powder flow from the coal mill is accelerated by the eccentric reducer 34 before the burner 3. Most of the coal powder flows along the inner wall of the bend due to centrifugal force. After the primary air flow enters the separation device 32 and the concentration device 33, approximately 50% of the primary air and 10%–15% of the coal powder are separated and led to the lower furnace 1 for combustion via the upper exhaust gas branch pipe 4 and the lower exhaust gas branch pipe 5. The remaining approximately 50% of the primary air and 85%–90% of the coal powder are concentrated and injected into the lower furnace 1 through the primary air channel 27 of the burner 3. After concentration, the coal powder concentration of the primary air is nearly doubled, reducing the heat absorption required for coal ignition, which is beneficial for ignition and stable combustion. The secondary air introduced by the swirl enters through the inner secondary air channel 28 and the outer secondary air channel 29, respectively, which can promptly entrain high-temperature hot flue gas and replenish the air required for combustion, which is beneficial for coal ignition and burnout. Both the inner and outer secondary air channels 28 and 29 are equipped with adjusting blades. Figure 3 The inner secondary air blade adjusting rod 30 and the outer secondary air blade adjusting rod 31 shown in Figure a respectively adjust the swirl blade angles of the inner and outer secondary air, thereby adjusting the swirl intensity of the secondary air to adapt to different combustion conditions. The blunt body 26 is made of silicon carbide and silicon nitride composite material, which is mixed and sintered in a certain proportion. It has high strength, high temperature resistance and good thermal conductivity, and its cross-section is streamlined, specifically elliptical or similar streamlined shape. When the primary air pulverized coal gas flow is ejected from the center of the burner 3, it will flow over the surface of the blunt body 26. The presence of the blunt body 26 changes the flow field of the airflow to form a stable, low-pressure recirculation zone downstream of the primary air nozzle, thereby enhancing the ignition and stable combustion capabilities.

[0033] When the pulverized coal gas flow is ejected from the primary air nozzle, the streamlined composite blunt body 26 acts as a barrier and guide for the gas flow. Due to the presence of the blunt body 26, a stable, low-pressure recirculation zone is formed downstream of the blunt body 26. At the same time, the inner secondary air passage 28 and the outer secondary air passage 29 of the burner 3 are strongly rotated by the air regulator. After the rotating gas flow leaves the nozzle, due to centrifugal force, a larger recirculation zone is formed in the central region of the axis. The recirculation zone generated by the composite blunt body 26 and the recirculation zone generated by the rotating gas flow superimpose and enhance each other, together constructing a powerful recirculation zone in front of the burner 3 nozzle with a larger volume, a more stable flow field, and the ability to continuously entrain high-temperature flue gas in the furnace. The high-temperature flue gas in the recirculation zone transfers heat to the subsequently ejected pulverized coal gas flow, reducing the ignition heat requirement of the pulverized coal. This allows the ignition heat to be quickly met even for anthracite with very low volatile matter, enabling the pulverized coal to ignite rapidly. The dual-adjustment air structure controls the mixing speed of air and pulverized coal by adjusting the swirl intensity of the internal and external secondary air. This ensures timely ignition of the pulverized coal while preventing NO emissions caused by excessively rapid mixing. x Increased production. The high-temperature resistance of the blunt body 26 ensures that it will not deform or be damaged in the high-temperature environment of the furnace, while the streamlined design reduces resistance to airflow and avoids excessive airflow disturbance affecting flame stability.

[0034] In the above technical solution, the structural design of the blunt body 26, separation device 32 and concentration device 33 of the dual-adjustment cyclone burner 3 enhances the ignition conditions of low volatile anthracite, significantly improves the stable combustion capability of burner 3, successfully achieves the minimum stable combustion load of 30% BRL, and does not require the addition of auxiliary fuel to assist combustion, thus providing a guarantee for deep peak shaving of the boiler. At the same time, it promotes the full combustion of pulverized coal and improves combustion efficiency.

[0035] In another technical solution, such as Figure 4 As shown, the water-cooled wall of the steam-water system adopts heat exchange tubes with differentiated configuration in different zones. That is, different specifications of heat exchange tubes are selected according to factors such as the heat load intensity and structural stress of different areas of the furnace. The boiler is equipped with a water-cooled wall. The water-cooled wall adopts a membrane wall structure, which is welded from multiple heat exchange tubes and fins. It is divided into the following areas according to the furnace region: the lower furnace 1 wing wall area, the lower furnace 1 non-wing wall area, the upper furnace 2 main body area, the four corner areas of the upper furnace 2, and the area 500mm above the tip of the flame deflector angle of the upper furnace 2. Areas A to D together constitute the lower furnace of the boiler, and areas E to I together constitute the upper furnace of the boiler. The heat exchange tubes of the water-cooled wall are configured according to the furnace region as follows: Lower furnace 1 wing wall area ( Figure 4Regions A and B in the middle are located in the high heat load area at the corner and have large structural stress. Therefore, internally threaded heat exchange tubes with an outer diameter of 32mm, a wall thickness of 6mm, and a pitch of 63mm are used. The thicker wall thickness enhances the structural strength, and the wider pitch is conducive to coping with high heat flow. The preferred tube material is 12Cr1MoVG alloy steel, which can withstand high temperature and large structural stress and avoid overheating and burning of the tube wall. Lower furnace 1 cold ash hopper area ( Figure 4 In area C), internally threaded heat exchange tubes with an outer diameter of 32mm and a wall thickness of 5.8mm are used. In areas with lower heat loads, thicker tube diameters are still selected to increase the structural strength of the cold ash hopper and prevent falling coke from damaging the water-cooled wall. The area of ​​the lower furnace 1 excluding the wing walls ( Figure 4 The heat load in the D area is relatively uniform. Optimized internally threaded heat exchange tubes with an outer diameter of 32mm, a wall thickness of 5.3mm, and a pitch of 53mm are used. The denser pitch helps to homogenize the heat flow and enhance cooling. 12Cr1MoVG alloy steel is preferred for the tube material to optimize flow resistance while ensuring cooling effect. Upper furnace 2 main area ( Figure 4 The heat load in region F is relatively low, so heat exchange tubes with an outer diameter of 28 mm and a wall thickness of 6 mm are used. The smaller tube diameter helps to increase the flow rate and enhance cooling at the same mass flow rate. 12Cr1MoVG alloy steel is preferred for the tube material. The four corner areas of the upper furnace 2 ( Figure 4 The E region of the structure is under stress concentration. Heat exchange tubes with an outer diameter of 28 mm and a wall thickness of 6.5 mm are used. The thicker wall thickness enhances the structural strength, strengthens the resistance to deformation, and is suitable for stress concentration conditions. The area 500mm above the tip of the flame in the upper furnace (2nd fold) Figure 4 In the G region of the process, considering the requirements of the bending process, heat exchange tubes with an outer diameter of 28mm and a wall thickness of 5.5mm are used. Due to the complex bending process involved, the thin-walled design is easy to manufacture. 12Cr1MoVG alloy steel is preferred for the tube material to avoid bending difficulties or tube cracking due to excessive wall thickness. Water-cooled wall area after furnace 2 ( Figure 4 In the H area, the front screen tubes are selected with an outer diameter of 76mm and a wall thickness of 14mm. The heat exchange tubes here need to take into account the load transmitted from the rear water-cooled wall, so large-size thick-walled heat exchange tubes need to be selected. Upper furnace 2 wall water-cooled walls ( Figure 4 The heat exchange tubes in Zone I (with an outer diameter of 28 mm and a wall thickness of 5.5 mm) are designed with small diameter and thin wall to minimize the thermal expansion difference caused by the large temperature difference between the outer wall and the main furnace water-cooled wall. The tubes are preferably made of 12Cr1MoVG alloy steel and are formed into an integral membrane structure by fin welding to ensure the furnace sealing.

[0036] During boiler operation, the high-temperature flue gas generated by combustion in the furnace transfers heat to the water-cooled wall heat exchange tubes through radiation and convection. The thick-walled heat exchange tubes in high-heat-load areas such as the lower furnace 1 wing wall effectively absorb heat and withstand high temperatures and structural stress. The heat exchange tubes in the upper furnace 2 and specific areas of the flame deflector are adapted to specifications based on heat load and process requirements, optimizing material usage and flow resistance while ensuring cooling. The water-cooled walls surrounding the furnace and the main water-cooled walls use heat exchange tubes of the same outer diameter, reducing the difference in thermal expansion between the two during operation and lowering thermal stress caused by inconsistent thermal expansion, thus avoiding problems such as fin cracking or pipe leakage. This is achieved through differentiated configuration of heat exchange tubes in each area, targeted application of internally threaded tubes, and a unified design of the water-cooled walls surrounding the furnace.

[0037] In the above technical solution, the heat exchange tube specifications are configured according to the heat load differences in different areas of the furnace, which ensures the safe and stable operation of the water-cooled wall as a whole, improves the heat exchange efficiency and reliability of the steam-water system, extends the service life of the water-cooled wall, and enhances the safety and reliability of the steam-water system operation.

[0038] In another technical solution, a throttling orifice plate is provided at the end of the downcomer supplying water to the water-cooled wall. Specifically, the boiler feedwater is distributed to each water-cooled wall loop through the downcomer. At the end of the downcomer connecting to the lower header in each loop, a throttling orifice plate is installed. The throttling orifice plate is made of high-temperature and high-pressure resistant stainless steel. The orifice diameter of the throttling orifice corresponding to the front and rear wall water-cooled wall loops of the furnace is one or more combinations of 36mm, 38mm, 47.5mm or 54mm, which is determined according to the resistance characteristics and design flow rate of each loop. For example, a larger orifice diameter is selected for loops with higher resistance and a smaller orifice diameter is selected for loops with lower resistance. The orifice diameter of the throttling orifice corresponding to the side wall water-cooled wall loops of the furnace is in the range of 42mm to 47mm, which is also adapted according to the loop resistance. The number of working fluid outlet pipes for each loop of the non-wing wall water-cooled wall in the lower furnace 1 has been adjusted from the traditional 3 to 2. The outlet pipes are made of the same material as the heat exchange tubes of the water-cooled wall, and the pipe diameter is compatible with the heat exchange tubes. They are connected to the water-cooled wall and the header by welding. The number of connecting pipes between the rear wall water-cooled wall of the upper furnace 2 and the lower header of the front screen superheater has been adjusted from 18 to 17. The connecting pipes are made of high-temperature resistant alloy steel.

[0039] The working fluid is transported from the economizer 19 outlet to the water-cooled wall circuit via the downcomer. When it flows through the orifice plate, the orifice diameter determines the flow rate of the working fluid through the circuit. By configuring different orifice diameters for the front and rear walls and side walls of the water-cooled wall circuit, the flow rate of each circuit is initially regulated, making the flow distribution more in line with the heat exchange requirements of each circuit. The number of outlet pipes in the non-wing wall water-cooled wall circuit of the lower furnace 1 is reduced, adjusting the flow resistance of the circuit. This, combined with the orifice diameter configuration, further balances the flow rate of each circuit in the lower furnace 1. The number of connecting pipes between the rear wall water-cooled wall of the upper furnace 2 and the lower header of the front superheater is optimized, which also adjusts the resistance characteristics of this path, ensuring uniform working fluid flow in the upper furnace 2 water-cooled wall. The optimized design of the entire flow distribution system keeps the working fluid flow deviation of each water-cooled wall circuit within a small range, avoiding heat transfer deterioration caused by insufficient local flow, ensuring hydrodynamic safety, and improving the reliability of the boiler at full load.

[0040] In the above technical solution, the refined configuration of the downcomer throttling orifice diameter, combined with the optimization of the number of connecting pipes, is obtained after detailed hydrodynamic resistance calculations. This constitutes active and precise control of the flow distribution of the water-cooled wall system, ensuring the stability and safety of hydrodynamics under full load conditions, and further improving the reliability margin of boiler operation.

[0041] In another technical solution, in the air distribution system, the burnout air nozzles 7 are respectively installed on the front and rear walls of the furnace. The number of nozzles is determined according to the furnace width and burnout air coverage requirements, and they are evenly distributed in the upper region of the furnace. They are not vertically aligned with the burners 3 in the horizontal direction, but are staggered. When the burnout air is injected into the upper part of the furnace from the front and rear walls, it can diffuse more evenly and cover the entire furnace cross-section, reducing airflow dead zones. This ensures that unburned fuel and combustible gas rising from the flame center can be fully mixed with air across the entire cross-section, improving the burnout rate and optimizing the flow field inside the furnace. The wall-mounted air nozzles 11 are arranged on the left and right walls of the furnace and are divided into multiple layers in the vertical direction, for example, three layers in the vertical direction: upper, middle, and lower. The number of nozzles in each layer is adapted according to the furnace height and width. The air supply volume of the 1 layer is independently adjustable. The air supply volume of each layer can be precisely controlled by adjusting the valve. The air outlet direction of the nozzle is designed to ensure that the airflow can flow parallel to the side water-cooled wall surface, ensuring that an oxidizing atmosphere is maintained near the wall surface in the easily corroded area, effectively inhibiting high-temperature sulfur corrosion. The wall-mounted air also has the function of flame shape control to prevent the flame from directly scouring the water-cooled wall tubes. The air distribution system also includes wing wall cooling air nozzles arranged at the wing walls at the four corners of the furnace, which are connected to the wing wall air box 10. These are corners where airflow is prone to form dead zones. The wing wall cooling air nozzles supplement air to the corners, eliminate the local reducing atmosphere, and prevent coking and corrosion. The air volume can be adjusted according to the operating conditions. During operation, the independently adjustable side wall wall-mounted air of the upper, middle and lower layers and the wing wall cooling air of the four corners work together to build a dynamically adjustable air protection layer on the water-cooled wall surface around the furnace.

[0042] During boiler operation, burnout air is ejected from the nozzles. Due to the arrangement of the front and rear walls and the horizontal spacing design with the burner 3, it can evenly cover the upper section of the furnace, providing sufficient oxygen for the later stage of pulverized coal combustion and promoting complete combustion of pulverized coal. According to the combustion conditions and corrosion risks of different height areas in the furnace, the air supply volume of each layer of wall-mounted air nozzles 11 is independently adjusted to maintain an oxidizing atmosphere near the side water-cooled wall surface, suppressing high-temperature corrosion. The lower layer of wall-mounted air can be adjusted according to the combustion conditions of the lower furnace 1, while the upper layer is adapted to the operating conditions of the upper furnace 2. The air ejected from the wing wall cooling air nozzles fills the flow dead zones in the four corners of the furnace, eliminating the reducing dead zones and further suppressing high-temperature corrosion in the corner areas.

[0043] In the above technical solution, the design of the burnout air nozzle 7, the wall-mounted air nozzle 11, and the wing wall cooling air nozzle synergistically optimizes the uniformity of air distribution in the furnace, effectively suppresses high-temperature corrosion caused by the combustion of high-sulfur coal, and promotes the burnout of pulverized coal, thereby improving combustion efficiency and environmental performance.

[0044] In another technical solution, the exhaust gas pipeline includes a lower exhaust gas branch pipe 5 and an upper exhaust gas branch pipe 4. The exhaust gas pipeline is led out from the separation device 32 in the burner 3 and is divided into a lower exhaust gas branch pipe 5 and an upper exhaust gas branch pipe 4. The corresponding exhaust gas nozzles include a lower exhaust gas nozzle and an upper exhaust gas nozzle. The lower exhaust gas nozzle is located at a height between the outlet of the burner 3 and the nearest downstream staged air nozzle, and the upper exhaust gas nozzle is located at a height between the outlet of the burner 3 and the burnout air nozzle 7.

[0045] When the pulverizing system is running, the pulverized coal gas flow passes through the separation device 32 and the concentration device 33 in the burner 3 for concentration separation. The light phase pulverized coal gas flow forms exhaust gas, which enters the exhaust gas pipeline. The exhaust gas is transported to the lower exhaust gas nozzle through the lower exhaust gas branch pipe 5 and injected into the area between the burner 3 and the staged air. This area is near the main combustion zone, where the pulverized coal in the exhaust gas participates in combustion and also plays a role in fuel grading. Another part of the exhaust gas is transported to the upper exhaust gas nozzle through the upper exhaust gas branch pipe 4 and injected into the area between the burner 3 outlet and the burnout air, which replenishes fuel and a small amount of oxygen for the burnout of the pulverized coal in this area.

[0046] In the above technical solution, the stratified exhaust gas supply design avoids interference from a large amount of concentrated exhaust gas supply to the main flame, forming a multi-stage fuel combustion process, and can also effectively suppress NO. x This process generates more efficient coal, improves fuel utilization, and ensures more complete combustion of pulverized coal, thus balancing environmental performance and combustion efficiency.

[0047] Traditional reheaters often employ long, serpentine tube bundles formed by multiple consecutive small-radius bends connected in series. In another technical solution, such as... Figure 5 As shown, the high-temperature reheater 18 is composed of multiple tube panels. Each tube panel is not a long, serpentine shape, but rather a U-shaped structure formed by a smooth, large-arc bend of one or more parallel heat exchange tubes, resulting in a 180° turn. Its bending radius is much larger than that of a traditional small elbow. Due to the large radius of curvature of the elbow, the change in the flow direction of steam is gradual, significantly reducing the local scouring force and thermal stress on the inner wall of the heat exchange tubes. This makes it less likely for the oxide scale generated by the high-temperature steam oxidation on the inner wall of the heat exchange tubes to peel off at the elbow due to stress concentration. Simultaneously, the smooth flow path also makes it easier to prevent the peeling off of even a small amount of oxide scale. It is easily carried away by the high-speed steam flow and will not stagnate or accumulate at the bend. The number of tube panels is determined according to the heat exchange area requirements of the reheater. The heat exchange tubes of the high-temperature reheater 18 are made of austenitic stainless steel that is resistant to high-temperature steam oxidation. Specifically, SA-213TP310HCbN or S30432 can be selected. These materials have excellent resistance to steam oxidation and high-temperature creep, and can withstand the long-term effects of the high-temperature environment in the upper part of the furnace. The outer diameter of the heat exchange tubes is set according to the flow rate and heat exchange requirements. The tube panels are connected by a header. The header material is compatible with the heat exchange tubes and is fixed by welding.

[0048] Steam heated by the low-temperature reheater 17 enters the high-temperature reheater 18 and flows through the heat exchange tubes of each U-shaped tube screen. The high-temperature flue gas in the upper part of the furnace transfers heat to the tube wall through radiation and convection. The tube wall then transfers heat to the steam flowing inside the tube, further raising the steam temperature to the design value. The U-shaped structure design reduces the number of bends in the heat exchange tubes, especially small-radius bends, which reduces steam flow resistance and the risk of oxide scale accumulation. Even if a small amount of oxide scale is generated, it is not easy to accumulate inside the tube and is easy to clean by blowing.

[0049] In the above technical solution, the U-shaped tube screen design and the austenitic stainless steel material resistant to high-temperature steam oxidation jointly solve the problem of oxide scale blockage under high reheat steam temperature, extend the service life of heat exchange tubes, and improve the reliability and stability of the steam-water system operation.

[0050] In another technical solution, such as Figure 6 As shown, it also includes a combustion-resistant strip covering part of the outer surface of the water-cooled wall to reduce heat absorption in that area, thereby increasing the local flue gas temperature. Figure 6 The shaded area indicates the area where the combustion belts are laid on the left and right walls of the boiler furnace. Figure 6 The shaded area (b) shows the area where the combustion-supporting strips are laid on the front and rear walls of the boiler furnace. These strips are continuously distributed on the front and rear walls of the furnace, extending from the bottom of the lower furnace 1 to below the burnout air nozzle 7, covering the water-cooled wall area corresponding to the main combustion zone. This ensures that the area maintains a sufficiently high temperature level, which is beneficial for the ignition and stable combustion of anthracite. On the left and right walls of the furnace, they are intermittently distributed in blocks, divided into multiple discrete, independent grid-like areas. Uncovered water-cooled wall tube areas are left between the blocks to prevent the overall temperature of the side walls from becoming too high. If the side walls were also continuously covered with combustion-supporting strips, the molten ash would easily... The slag adheres extensively to the entire wall surface, forming huge, difficult-to-remove clumps of coke. If it collapses, it will severely impact the cold ash hopper below. The intermittent arrangement divides the high-temperature zone. Even if there is slight coking on each small piece, it will be restricted by the surrounding normal water-cooled wall area with a lower temperature, preventing it from forming a large block and thus effectively controlling the scale and risk of coking. Furthermore, the absence of the combustion belt in the area below the inflection point of the furnace cold ash hopper allows the water-cooled wall in the cold ash hopper area to absorb heat normally, maintaining a relatively low wall temperature. After the molten slag falls into this area, it can quickly cool, solidify, and smoothly slide down to the slag discharge port, avoiding the accumulation of coke clumps and ensuring the smooth operation of the boiler slag discharge system.

[0051] In the above technical solution, the differentiated arrangement of continuous front and rear of the combustion belt, intermittent side walls, and elimination of the cold ash hopper not only meets the furnace temperature requirements for stable combustion of anthracite, but also effectively controls the risk of coking, ensures the continuous and stable operation of the boiler, and reduces maintenance workload and downtime.

[0052] The method for operating the W-flame ultra-supercritical boiler using high-sulfur, low-volatile anthracite coal requires a furnace design that meets specific high-load levels, with optimized furnace heat load and geometry, and a relatively small furnace volume. The furnace must satisfy the following heat load parameters: a total furnace volumetric heat load of not less than 90 kW / m³. 3 The volumetric heat load of the area under the arch shall not be less than 220 kW / m² 3 The heat load on the arch section shall not be less than 5.5 MW / m 2 The heat load at the arch cross section shall not be less than 3.0 MW / m. 2 These parameters are achieved by optimizing the furnace geometry and burner 3 arrangement. Through reasonable heat load distribution, the furnace heat absorption is reduced, the outlet working fluid temperature is lowered, and hydrodynamic characteristics and material thermal stress are indirectly improved. A gas ignition device designed with a total input heat of 18% of the boiler's maximum continuous evaporation capacity is installed to support cold start-up and stable combustion under low load. A duct burner 3 is installed on the hot primary air main pipe to increase the hot primary air temperature under low load conditions. The gas ignition device includes a gas pipeline, an igniter, and a flame detector, arranged near the burner 3. The method includes the following steps: Combustion organization steps: Start the gas ignition device to ignite the pulverized coal gas flow from burner 3. By adjusting the operating parameters of the pulverizing system and the primary air flow, maintain a high pulverized coal concentration environment in the primary air channel 27 of burner 3. The pulverized coal concentration is controlled at 1.15~1.5kg pulverized coal / kg primary air through thick-thickness separation, which is 1.8~2 times the pulverized coal concentration of conventional double-adjustable swirl burners, significantly reducing the ignition heat demand. Control the exhaust gas to be divided into at least two streams and sent from different height positions in the furnace. Adjust the exhaust gas distribution ratio according to the boiler load. Under low load, appropriately increase the amount of exhaust gas sent from the lower layer, and under high load, distribute it evenly. Hydrodynamic control steps: Throughout the boiler's operation from startup to full load, especially during low-load operation, it is necessary to monitor parameters such as feedwater flow rate, pressure, and temperature of each circuit, and adjust the feedwater pump and throttling device. By adjusting the output flow rate of the feedwater pump and the throttling valve of the downcomer, the mass flow velocity of the working fluid flowing through the water-cooled wall of the lower furnace zone 1 is controlled to be no less than 1150 kg / (m³). 2 •s), to ensure effective cooling of the water-cooled wall in the high heat load zone of the lower furnace 1, and to control the mass flow rate of the working fluid flowing through the water-cooled wall in the upper furnace 2 zone to be between 1750 and 1850 kg / (m³). 2 Between ·s), the cooling effect and flow resistance are balanced. The flow rate of each loop is monitored in real time by a flow monitoring device, and the control parameters are dynamically adjusted according to the monitoring data. Wall atmosphere control steps: Based on the boiler load and combustion conditions, the air volume of each layer of wall-mounted air box is controlled by adjusting the air volume of the wall-mounted air box and the opening of the air supply dampers on the upper, middle and lower layers of the side wall. The oxygen concentration near the water-cooled wall is maintained above 2%. The oxygen concentration near the wall is monitored in real time by oxygen concentration sensors arranged in the furnace. The air volume of the wall-mounted air is adjusted in a timely manner according to the monitoring results to ensure that the wall is always in an oxidizing atmosphere, blocking corrosive gases such as H2S from contacting the pipe wall and inhibiting high-temperature corrosion.

[0053] When the boiler is started, the gas ignition device is activated first. After the furnace temperature rises to a certain level, pulverized coal is introduced for combustion, and the combustion organization steps are executed to establish a stable combustion flame. During the boiler load increase process, the hydrodynamic control steps are executed simultaneously, and the mass flow rate of the working fluid in the water-cooled wall is adjusted according to the load changes to ensure hydrodynamic stability. Throughout the entire operation, the wall atmosphere control steps are continuously executed, and the oxidizing atmosphere on the wall is maintained through real-time monitoring and adjustment.

[0054] In the above technical solution, the combustion organization step enhances the fuel combustion effect, the hydrodynamic control step ensures the safety of the water-cooled wall, and the wall atmosphere control step effectively inhibits high-temperature corrosion. This operation control method is highly compatible with the boiler structural design, and the steps work together to ensure the stable operation of the boiler when burning high-sulfur, low-volatile anthracite coal, under the premise of meeting the furnace heat load parameter requirements and the support of the gas ignition device. This ensures stable combustion at low load, hydrodynamic safety, and wall corrosion prevention.

[0055] The 660MW-class coal-fired power generation unit includes the aforementioned W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal, as well as auxiliary equipment such as a steam turbine, generator, dust collector, and desulfurization and denitrification device 22. The boiler and steam turbine are connected through steam pipelines, and the steam turbine and generator are connected through couplings, forming a complete thermodynamic cycle and power generation system. The power generation unit is designed to have a rated power generation capacity of 660MW. As the core equipment, the boiler integrates a combustion system with a composite bluff body 26, a coordinated air distribution system, a stratified exhaust gas fuel supply system, and a steam-water system with a mixing header and a special reheater. It can stably reach and maintain a high steam parameter operating state of ultra-supercritical. Its ultra-supercritical parameters are: main steam pressure not lower than 29.3 MPa.g, main steam temperature not lower than 605℃, reheat steam outlet temperature from the boiler high-temperature reheater 18 to the intermediate pressure cylinder of the turbine not lower than 623℃, and maximum continuous evaporation capacity (BMCR) of 2010 t / h. This set of steam parameters marks a significant leap from the parameter level of traditional W-flame boilers.

[0056] After the boiler starts up, the heat generated by the combustion of high-sulfur, low-volatile anthracite is transferred to the working fluid through the coordinated work of the combustion system, air distribution system, fuel supply system and steam-water system. The working fluid is heated to ultra-supercritical steam. The main steam flows out of the boiler outlet and is transported to the high-pressure cylinder of the turbine through the steam pipeline. The high-pressure cylinder impeller rotates and does work. The steam after doing work is discharged from the high-pressure cylinder and sent to the boiler reheater. After being heated to the set temperature by the low-temperature reheater 17 and the high-temperature reheater 18, it is sent to the intermediate-pressure cylinder of the turbine to continue to expand and do work. Then it enters the low-pressure cylinder to do more work. The rotational motion of the turbine is transmitted to the generator through the coupling. The generator converts mechanical energy into electrical energy and transmits it to the power grid. The flue gas generated by combustion is treated by the dust collector and the desulfurization and denitrification device 22 and is discharged into the atmosphere after meeting the environmental emission standards. Through optimized boiler design, the entire generator unit is fully adapted to the combustion characteristics of high-sulfur, low-volatile anthracite, achieving efficient, clean, and stable power generation, meeting the power output demand of 660MW and the peak-shaving requirements of the new power system.

[0057] In the aforementioned technical solution, high-sulfur, low-volatile anthracite pulverized coal is efficiently, cleanly, and stably combusted in the boiler. The resulting high-temperature flue gas heats water into high-parameter ultra-supercritical steam. This steam is introduced into a steam turbine, driving the turbine generator unit to rotate and perform work, ultimately outputting 660MW of electrical energy to meet the grid's requirements for deep peak shaving and rapid load change. This generator unit not only improves power generation efficiency and reduces coal consumption and carbon emissions, meeting the requirements of the national clean carbon reduction policy, but also possesses excellent deep peak shaving capabilities and operational reliability, adapting to the needs of new power systems for coal-fired power units. It provides a complete application solution for the efficient and clean utilization of high-sulfur, low-volatile anthracite coal.

[0058] This embodiment involves a 660MW-class ultra-supercritical pulverized coal boiler installed at the Liutang Power Plant in Guizhou Province, used to burn typical local high-ash, high-sulfur anthracite coal. The received-basis industrial analysis data for this coal type are as follows: Moisture (M) ar = 8.5%, Ash A r = 31.08%, dry ash-free volatile matter V daf = 9.28%, total sulfur S ar = 2.85%, Lower heating value Qnet, ar =20MJ / kg. The rated steam parameters of the boiler are: main steam pressure 29.3MPa.g, main steam temperature 605℃, reheat steam outlet temperature 623℃, and maximum continuous evaporation capacity (BMCR) 2010t / h.

[0059] Firstly, regarding furnace dimensions and pipe material selection: Optimize furnace dimensions to take into account the coking characteristics of coal, using a smaller furnace size and a larger furnace volumetric heat load of not less than 90 kW / m³.3 The volumetric heat load of the area under the arch shall not be less than 220 kW / m² 3 The heat load on the arch section shall not be less than 5.5 MW / m 2 The heat load at the arch cross section shall not be less than 3.0 MW / m. 2 .

[0060] The height ratio of the upper and lower furnace chambers 1 was optimized. The total height of the furnace chamber (excluding the cold ash hopper) was 57.4m. The dividing line between the upper and lower furnace chambers 1 was set at 29.5m from the bottom of the furnace, so that the lower furnace chamber 1 accounted for 51.3% of the total furnace height (the traditional design is 55%).

[0061] Lower furnace 1 water-cooled wall: Lower furnace 1 cold ash hopper area ( Figure 4 In area C of the furnace, Φ32mm×5.8mm ordinary internal threaded pipes or plain pipes are used; above the cold ash hopper, optimized internal threaded pipes are used; in the lower furnace 1 area excluding the wing walls ( Figure 4 The D area in the heat exchange system uses Φ32×5.3mm 12Cr1MoVG steel pipes with a tube pitch of 53mm. The wing wall area ( Figure 4 Regions A and B are heated more intensely and therefore use Φ32×6mm heat exchange tubes with a pitch of 63mm. Upper furnace 2 water-cooled wall: main area ( Figure 4 The F area in the middle uses Φ28×6mm heat exchange tubes, and the four corner areas ( Figure 4 The stress concentration area in region E is reinforced to Φ28×6.5mm, and the area 500mm above the tip of the flame deflector ( Figure 4 The G region in the middle) uses Φ28×5.5mm heat exchange tubes, and the rear water-cooled wall region ( Figure 4 The H area in the middle) uses Φ76mm×14mm heat exchange tubes for the front screen tubes, and the wall is surrounded by water-cooled walls ( Figure 4 The heat exchange tubes in Zone I are uniformly Φ28×5.5mm.

[0062] Second, hydrodynamic control: The mass flow rate of the working fluid flowing through the water-cooled wall in the lower furnace zone 1 shall not be less than 1150 kg / (m³). 2 •s), to ensure effective cooling of the water-cooled wall in the high heat load zone of the lower furnace 1, and to control the mass flow rate of the working fluid flowing through the water-cooled wall in the upper furnace 2 zone to be between 1750 and 1850 kg / (m³). 2Between ·s), the throttling orifice diameters of the front and rear water-cooled walls are adjusted to 36mm, 38mm, 47.5mm, and 54mm (previously, 43mm, 41mm, 53mm, and 54mm were used for non-functional circuits), and the throttling orifice diameters of the side water-cooled walls are adjusted to 42mm~47mm (previously, 54mm~64mm were used for non-functional circuits). The number of lead-out pipes for each circuit of the front and rear water-cooled walls of the lower furnace 1, except for the wing wall circuit, is reduced from 3 to 2. The number of connecting pipes for the bottom pipe of the rear water-cooled fireplace in the upper furnace 2 to the lower header of the front water screen is reduced from 18 to 17.

[0063] After full-load hydrodynamic calculations and operational verification, the flow deviation of each loop is less than 5%, the wall temperature distribution is uniform, and there is no heat transfer deterioration or flow instability.

[0064] Third, the reheater adopts a two-stage arrangement: The reheat system adopts a two-stage arrangement of low-temperature reheater 17 and high-temperature reheater 18.

[0065] The low-temperature reheater 17 is located in the tail convection flue, with its outlet divided into left and right sides, which are connected to the cross mixing header. After mixing, the mixture enters the left and right emergency spray desuperheaters. The inlet of the low-temperature reheater 17 is also equipped with the left and right emergency spray desuperheaters.

[0066] The high-temperature reheater 18 is located in the high-temperature zone at the top of the furnace. It adopts a large U-shaped structure. The low-temperature section is SA-213T91, and the high-temperature section is upgraded to SA-213TP310HCbN and S30432.

[0067] Data from 168 hours of full-load operation showed that the temperature difference between the left and right sides of the reheater outlet was less than 10°C, and no scale blockage occurred.

[0068] Fourth, combustion system settings: The combustion system is equipped with 24 HPAX-EX type double-adjustable swirl burners 3, 12 on the front and 12 on the back walls. Each burner 3 has a silicon carbide + silicon nitride composite blister 26 integrated at the end of the primary air nozzle. The pulverizing system uses 6 medium-speed mills with direct-fired combustion, with 4 burners 3 corresponding to each mill. After the primary air flow enters the separation device 32 and the concentration device 33, about 50% of the primary air and 10% to 15% of the pulverized coal are separated and led to the lower furnace 1 for combustion through the upper exhaust gas branch pipe 4 and the lower exhaust gas branch pipe 5. The 24 exhaust gas branches are fed in layers, with 12 lower exhaust gas branches being fed into the combustion chamber. Between the burner 3 outlet and the staged air nozzle, 12 upper exhaust gases are sent between the burner 3 outlet and the burnout air nozzle 7. The remaining approximately 50% of the primary air and 85%–90% of the pulverized coal are concentrated and injected into the lower furnace 1 through the primary air channel 27 of the burner 3 for combustion. After concentration, the pulverized coal concentration of the primary air is nearly doubled. There are a total of 30 burnout air nozzles 7, 15 on the front and 15 on the back walls, located vertically at 5.5m above the arch. At the same time, 24 sets of natural gas ignition devices are configured. The total thermal power is designed according to 18% BMCR. During cold start, the primary air temperature can be raised to over 200℃.

[0069] Actual operation verification showed stable combustion under 30%~100% BRL load, NO x Emissions are controllable.

[0070] Fifth, the wall-mounted ventilation system, the wing-wall ventilation system, and the fire-preserving strip are designed in a coordinated manner: The wall-mounted air system is equipped with three independently adjustable air boxes (upper, middle, and lower) along the side water-cooled walls. The wing wall cooling air is arranged at the junction of the four corner wing walls and the front and rear walls of the furnace, connected to the wing wall air box 10, and drawn from the staged air box 9. Each of the four corners is equipped with an adjustable damper. The sanitary strip is arranged in a strip shape on the front and rear walls, and in a grid pattern on the left and right side walls with sufficient effective intervals. The sanitary strip below the inflection point of the cold ash hopper is eliminated. The sanitary strip is laid in the combustion zone and burnout air zone of the lower furnace 1.

[0071] Based on the above boiler design and control methods, the W-flame ultra-supercritical boiler scheme disclosed in this invention achieves the following beneficial effects: Firstly, in the Liutang project in Guizhou, the boiler steam parameters were increased to 29.3 MPa.g / 605℃ / 623℃, breaking through the technical bottleneck that had long been stagnant at the 26.15 MPa.g / 585℃ / 583℃ level due to hydrodynamic safety and high-temperature corrosion limitations. It also passed the trial operation assessment, with all performance indicators meeting the design requirements, fully demonstrating its technological maturity and broad engineering applicability.

[0072] Secondly, by implementing optimized upper and lower furnace zones, adjusting pipe diameter and pitch, classifying mass flow rate control, and refining the configuration of throttling orifices, thermal deviation and uneven flow distribution were effectively suppressed, heat transfer deterioration or flow instability were avoided, and the requirements for safe operation under full load, including dry operation at 30% BRL and above, were met.

[0073] Then, under the condition of burning dry anthracite with a volatile content of only 9.28% on an ash-free basis, stable combustion at the minimum load of 30% BRL was successfully achieved without the need for auxiliary fuel to assist combustion. The boiler efficiency under rated conditions can reach 93%, which meets the requirements of the new power system for flexible operation of coal-fired power units.

[0074] Finally, by applying the HPAX-EX low-NOx burner, employing stratified exhaust gas feed technology, and optimizing the burnout air arrangement, deep staged combustion of fuel and air was achieved, enabling the initial NOx emission concentration at the boiler outlet to reach the design value (≤690mg / Nm³). 3 This reduces the operational burden on subsequent flue gas denitrification systems.

[0075] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0076] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal, characterized in that, include: A combustion system includes a furnace and multiple burners disposed on the front and rear walls of the furnace. The furnace includes a lower furnace and an upper furnace. The height of the lower furnace accounts for 50-54% of the total height of the furnace. The primary air nozzle of the burner is provided with a blunt body at its end. The air distribution system includes a staged air nozzle and a burnout air nozzle for supplying combustion air into the furnace, and a wall-mounted air nozzle for supplying air to the side wall of the furnace. The burnout air nozzle and the burner are arranged at intervals in the horizontal direction, and the air outlet direction of the wall-mounted air nozzle is set to be parallel or approximately parallel to the side water-cooled wall. A fuel supply system includes a primary air duct for supplying pulverized coal to the burner, and a waste gas duct for delivering the oxygen-deficient pulverized coal gas stream as waste gas into the furnace through a waste gas nozzle independent of the burner, the waste gas duct being configured to deliver the waste gas in at least two streams at different heights in the furnace. The steam-water system includes a water-cooled wall arranged in the furnace and a reheater for heating steam. The water-cooled wall is connected to an intermediate mixing header for mixing the working fluid at a height between the lower and upper furnace. The reheater includes a low-temperature reheater and a high-temperature reheater. The outlet of the low-temperature reheater is connected to a cross-mixing header for cross-mixing steam flows from the left and right sides of the furnace. Both the inlet and outlet of the low-temperature reheater are equipped with emergency water spray desuperheaters.

2. The W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal according to claim 1, characterized in that, The burner is a dual-adjustable swirl burner, and the bluff body is made of a silicon carbide and silicon nitride composite material with a streamlined cross-section to form a stable recirculation zone downstream of the primary air nozzle.

3. The W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal according to claim 1, characterized in that, The water-cooled walls of the steam-water system employ zoned, differentiated heat exchange tube configurations, and the boiler is equipped with enclosing water-cooled walls; the heat exchange tubes of the water-cooled walls are configured according to the furnace region as follows: The lower furnace wing wall area uses heat exchange tubes with an outer diameter of 32mm, a wall thickness of 6mm, and a pitch of 63mm; The lower furnace lining, excluding the wing walls, uses heat exchange tubes with an outer diameter of 32mm, a wall thickness of 5.3mm, and a pitch of 53mm. The cold ash hopper area in the lower furnace uses heat exchange tubes with an outer diameter of 32mm and a wall thickness of 5.8mm; The main area of ​​the upper furnace chamber uses heat exchange tubes with an outer diameter of 28mm and a wall thickness of 6mm; The four corner areas of the upper furnace chamber use heat exchange tubes with an outer diameter of 28mm and a wall thickness of 6.5mm; The area 500mm above the tip of the flame deflector in the upper furnace uses heat exchange tubes with an outer diameter of 28mm and a wall thickness of 5.5mm. The heat exchange tubes with an outer diameter of 76mm and a wall thickness of 14mm are selected for the front screen tubes in the water-cooled wall area after the furnace is installed. The water-cooled wall of the upper furnace lining uses heat exchange tubes with an outer diameter of 28mm and a wall thickness of 5.5mm.

4. The W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal according to claim 3, characterized in that, The downcomer supplying water to the water-cooled wall is equipped with a throttling orifice plate. The orifice diameter of the throttling orifice corresponding to the front and rear wall water-cooled wall circuits of the furnace is one or more combinations of 36mm, 38mm, 47.5mm or 54mm, and the orifice diameter of the throttling orifice corresponding to the side wall water-cooled wall circuits of the furnace is in the range of 42mm to 47mm. The number of working fluid outlet pipes for each loop of the lower furnace non-wing wall water-cooled wall is 2, and the number of connecting pipes between the upper furnace rear wall water-cooled wall and the lower header of the front screen superheater is 17.

5. The W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal according to claim 1, characterized in that, In the air distribution system, the burnout air nozzles are respectively installed on the front and rear walls of the furnace, and the wall-mounted air nozzles are arranged on the left and right walls of the furnace and are divided into multiple layers in the vertical direction. The air supply volume of each layer of wall-mounted air nozzles can be adjusted independently. The air distribution system also includes wing wall cooling air nozzles arranged at the four corners of the furnace.

6. The W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal according to claim 1, characterized in that, The exhaust gas pipeline includes a lower exhaust gas branch pipe and an upper exhaust gas branch pipe, and the corresponding exhaust gas nozzles include a lower exhaust gas nozzle and an upper exhaust gas nozzle. The lower exhaust gas nozzle is located between the burner outlet and the nearest downstream staged air nozzle, and the upper exhaust gas nozzle is located between the burner outlet and the burnout air nozzle.

7. The W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal according to claim 1, characterized in that, The high-temperature reheater is composed of multiple tube panels. Each tube panel is a U-shaped structure formed by bending one or more parallel heat exchange tubes into a 180° turn. The heat exchange tubes of the high-temperature reheater are made of austenitic stainless steel that is resistant to high-temperature steam oxidation.

8. The W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite coal according to claim 1, characterized in that, It also includes a flame-retardant band covering part of the outer surface of the water-cooled wall, the flame-retardant band being continuously distributed on the front and rear walls of the furnace, and discontinuously distributed in blocks on the left and right walls of the furnace, and the flame-retardant band not being arranged in the area below the inflection point of the furnace cold ash hopper.

9. A method for operating and controlling a W-flame ultra-supercritical boiler according to any one of claims 1-8, characterized in that, The furnace chamber meets the following heat load parameters: the total furnace volumetric heat load is not less than 90 kW / m³. 3 The volumetric heat load of the area under the arch shall not be less than 220 kW / m². 3 The heat load on the arch section shall not be less than 5.5 MW / m 2 The heat load at the arch cross section shall not be less than 3.0 MW / m. 2 The method includes the following steps: [The system is equipped with a gas ignition device designed to handle a total input heat of 15-20% of the boiler's maximum continuous evaporation capacity.] Combustion organization steps: Maintain a high coal powder concentration environment in the primary air duct of the burner, achieve 1.15~1.5kg coal powder / / kg primary air through rich-lean separation, and control the exhaust gas to be divided into at least two streams and sent into the furnace from different height positions; Hydrodynamic control steps: Control the working fluid mass flow velocity through the water-cooled wall in the lower furnace region to be no less than 1150 kg / (m³). 2 •s), and control the mass flow rate of the working fluid flowing through the water-cooled wall of the upper furnace region to be between 1750 and 1850 kg / (m³). 2 Between ·s); Wall atmosphere control steps: By adjusting the airflow along the wall, the oxygen concentration near the water-cooled wall surface is maintained at above 2%.

10. A 660MW-class coal-fired power generating unit, characterized in that, The invention includes a W-flame ultra-supercritical boiler for burning high-sulfur, low-volatile anthracite as described in any one of claims 1 to 8, wherein the ultra-supercritical parameters of the boiler are: main steam pressure not less than 29.3 MPa.g, main steam temperature not less than 605°C, and reheat steam outlet temperature not less than 623°C.

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