A 232mw large capacity circulating fluidized bed hot water boiler

Abstract

This invention belongs to the field of boiler technology and provides a 232MW large-capacity circulating fluidized bed hot water boiler. It includes a high-energy ignition device, a fully membrane-walled isobaric air chamber, a primary air chamber, an air distribution plate, a coal feeding device at the furnace front, a boiler ash removal device, a secondary air box, a furnace, a high-temperature insulated separator, risers, a return feeder, a diverting flue, a tail-end vertical flue, an economizer, an air preheater, and a compartmented outlet flue. The high-temperature insulated separator is a fully downward-sloping, stepless insulated separator; the return feeder is a dual-path return structure; the tubes of the economizer and air preheater form the tail-end heating surface, which is a high-heat-exchange, self-cleaning ash-removing tube array. This invention features more stable combustion, higher separation efficiency, low flue gas resistance, reliable operation, and significant energy-saving and wear-reducing effects. It can burn various fuels such as bituminous coal, lignite, and low-quality coal, making it suitable for large-scale centralized heating projects in northern China.

Description

Technical Field

[0001] This invention belongs to the field of boiler technology and relates to a circulating fluidized bed hot water boiler, specifically a 232MW large-capacity circulating fluidized bed hot water boiler. Background Technology

[0002] With the continuous increase in demand for large-scale centralized heating in cold regions of my country, traditional hot water boilers, limited by capacity, are unable to meet the demands of large-scale heating. Currently, the capacity of a single circulating fluidized bed (CFB) hot water boiler is generally below 168MW both domestically and internationally. Following the trend of replacing small-capacity boilers with large-capacity ones, there is a lack of mature design, manufacturing, and operation technologies for ultra-large-capacity CFB hot water boilers exceeding 168MW. While CFB boilers effectively address the issue of low initial NOx emissions from most lean coal and bituminous coal fuels, the problem of high initial NOx emissions from high-volatile fuels such as lignite, long-flame coal, and biomass fuels remains unresolved. The current industry average emission level is 120–150 mg / Nm3, which meets current national boiler air pollutant emission standards, but not in regions with special emission values ​​or higher standards. This impacts the low-cost pollution control advantage of CFB boilers. How to maximize the energy efficiency of the CFB boiler itself and the system, reduce fuel consumption, and decrease carbon emissions is a pressing issue for the industry. Currently, large-capacity, high-efficiency, and ultra-low-emission circulating fluidized bed hot water boilers are core and key equipment in urban centralized heating, industrial park heat source upgrades, and clean heating, representing the development direction of efficient and clean heating technology.

[0003] From the perspective of the current development status in my country, the circulating fluidized bed boiler technology has achieved independent control and is mature in the application of small and medium capacity boilers. The largest capacity hot water boiler currently in use is only 168MW, while ultra-large capacity hot water boilers of 200MW and above are still in the early stages of technological breakthroughs, with zero market cases. With the increasing requirements for long-distance grid-connected heating, combined heat and power peak shaving, and ultra-low emissions in northern regions, traditional small and medium capacity equipment can no longer meet the needs of system energy efficiency improvement and low-carbon development, resulting in a significant gap in large-capacity high-end equipment.

[0004] Internationally, in developed countries such as Europe and the United States, the mainstream application capacity of circulating fluidized bed hot water boilers is generally below 168MW. There is insufficient investment in the research and development of ultra-large capacity products, a lack of engineering application cases, and a mature industrialization technology system has not yet been formed. Driven by energy structure transformation and environmental protection policies, the international market demand for high-efficiency, low-nitrogen, and wide-fuel adaptability large-capacity heating boilers continues to grow, but there are very few companies with research and development and manufacturing capabilities.

[0005] The following technical bottlenecks are commonly encountered in the process of increasing capacity:

[0006] 1. With the increase of furnace volume, the bed material circulation becomes uneven, which can easily lead to problems such as localized uneven burning, coking, and uneven temperature distribution;

[0007] 2. Conventional high-temperature separators are arranged horizontally or downwards, with a stepped structure, resulting in low separation efficiency, high resistance, and easy material blockage;

[0008] 3. A single return feeder and return pipe correspond to a large cross-section furnace, resulting in uneven distribution of returned material in the furnace;

[0009] 3. The tail heating surface is severely worn and accumulates dust, requiring frequent soot blowing, resulting in short equipment lifespan and high operating and maintenance costs;

[0010] 4. Large-capacity boilers have poor matching between in-furnace desulfurization and denitrification, making it difficult to achieve both low emissions and high efficiency;

[0011] 5. There is a lack of mature design, manufacturing and operation technologies for 232MW-class ultra-large capacity circulating fluidized bed hot water boilers.

[0012] The aforementioned problems have become urgent technical challenges to be solved in the field of clean heating. Summary of the Invention

[0013] To overcome the shortcomings of existing technologies, this invention provides a 232MW large-capacity circulating fluidized bed hot water boiler, which has the advantages of large capacity, high efficiency, low emissions, and long service life.

[0014] A 232MW large-capacity circulating fluidized bed hot water boiler includes a high-energy ignition device, a full-membrane wall structure isobaric air chamber, a primary air chamber, an air distribution plate, a coal feeding device in front of the furnace, a boiler ash removal device, a secondary air box, a furnace, a high-temperature insulated separator, risers, a return feeder, a diverting flue, a tail vertical flue, an economizer, an air preheater, and a compartmented outlet flue. The air distribution plate is located at the bottom of the furnace and is connected to the full-membrane wall structure isobaric air chamber. The rear side of the full-membrane wall structure isobaric air chamber connected to the primary air chamber. The boiler ash removal device passes through the full-membrane wall structure isobaric air chamber and the air distribution plate and is connected to the bottom of the furnace. The high-energy ignition device is located behind the primary air chamber. The coal feeding device in front of the furnace is located at the lower part of the front wall of the furnace. The secondary air box is located around the lower part of the furnace and is located above the coal feeding device in front of the furnace. The upper exhaust end of the furnace is connected to the high-temperature... The inlet end of the adiabatic separator is connected to the air inlet, the lower part of the high-temperature adiabatic separator is connected to the riser, the lower part of the riser is connected to the feed inlet of the return feeder, the discharge end of the return feeder is connected to the lower part of the rear wall of the furnace, the exhaust end of the high-temperature adiabatic separator is connected to the inlet of the diverting flue, the outlet of the diverting flue is connected to the inlet end of the tail vertical shaft flue, the economizer and the air preheater are connected and arranged from top to bottom in the tail vertical shaft flue, the air preheater is connected to the outlet end of the tail vertical shaft flue, and the compartmented outlet flue is connected to the outlet end of the air preheater; the high-temperature adiabatic separator is a fully downward inclined stepless adiabatic separator, the return feeder is a one-to-two double-path return structure, the tubes of the economizer and the air preheater constitute the tail heating surface, the tail heating surface is a strong heat exchange self-cleaning tube array, the tube arrays are staggered, and the uppermost layer of each tube array is equipped with anti-wear protective tiles.

[0015] Furthermore, the furnace includes an upper dilute phase zone, a lower dense phase zone, and a furnace water-cooled screen. The upper dilute phase zone is located above the lower dense phase zone. The furnace water-cooled screen is inserted inside the upper dilute phase zone of the furnace. The width of the lowermost part of the lower dense phase zone is the same as that of the upper dilute phase zone. The depth of the lower dense phase zone is 0.35-0.4 times that of its uppermost part. The upper dilute phase zone and the furnace water-cooled screen are the main heat transfer areas. The flue gas velocity in the upper dilute phase zone and the lower dense phase zone is 4.6 m / s.

[0016] Furthermore, the high-temperature insulated separator includes an inlet tangential acceleration section, a straight cylinder, an inverted cone, and an exhaust center cylinder. The inlet tangential acceleration section is located at the upper side of the straight cylinder and is connected to the upper exhaust end of the furnace through a non-metallic expansion joint. The inverted cone is located at the lower end of the straight cylinder, and the exhaust center cylinder is located at the exhaust end of the top of the straight cylinder. The exhaust center cylinder is eccentrically positioned with respect to the centerline of the straight cylinder.

[0017] Furthermore, the height of the tangential acceleration section is 0.8 times the diameter of the straight cylinder, the height of the straight cylinder is 1.25 times its diameter, the throat velocity at the point where the tangential acceleration section is tangent to the straight cylinder is designed to be 28 m / s-28.5 m / s, the angle between the outer side of the inverted cone and the vertical direction is 12°, and the insertion depth of the exhaust center cylinder is 0.35-0.4 times the height of the tangential acceleration section.

[0018] Furthermore, the outlet ends of the secondary air boxes are staggered on the front and rear walls of the furnace, the air velocity at the outlet end of the secondary air boxes is 95 m / s, and the height between the outlet end of the secondary air boxes and the air distribution plate is 3.2-4.2 m.

[0019] Furthermore, the return feeder includes a return feeder discharge pipe, a return air chamber, a diversion chamber, and double return legs. The upper end of the return feeder discharge pipe is connected to the riser, the return air chamber is connected to the return feeder discharge pipe, the return air chamber is connected to the diversion chamber, and the diversion chamber is connected to the double return legs.

[0020] Furthermore, the boiler return water end is the boiler drum. After flowing through the centralized downcomer to the decentralized downcomer, the water enters the front water-cooled wall inlet header, the rear water-cooled wall inlet header, the two side water-cooled wall inlet headers, and the water-cooled screen inlet header. The water flows upward through the water-cooled walls to their respective outlet headers and then enters the water-cooled collection header together. After being collected in the water-cooled collection header, the water splits into two paths and enters the lower economizer header. The economizer tube bank has a serpentine tube structure and flows upward counterclockwise to the economizer outlet header. The boiler drum is connected to the water-cooled collection header by recirculation pipe I, and the water-cooled collection header is connected to the economizer outlet header by recirculation pipe II.

[0021] The advantages of this invention compared to the prior art are:

[0022] 1. World's first in capacity: The world's first 232MW circulating fluidized bed hot water boiler, breaking the industry's capacity limit;

[0023] 2. More stable combustion: The dual-path return structure ensures a uniform temperature field in the furnace, preventing uneven burning and coking;

[0024] 3. Higher separation efficiency: The fully downward-inclined, stepless high-temperature insulated separator has low flue gas resistance, high separation efficiency, and reliable operation;

[0025] 4. Significant energy saving and wear reduction: The self-cleaning ash pipe reduces wear by more than 30%, extending the service life of the equipment;

[0026] 5. Environmentally friendly and ultra-low emissions: Integrated desulfurization and denitrification in the furnace, with denitrification efficiency ≥80% and desulfurization efficiency ≥95%, achieving ultra-low emission standards without the need for complex back-end equipment;

[0027] 6. High applicability: It can burn a variety of fuels such as bituminous coal, lignite, and low-quality coal, making it suitable for large-scale centralized heating projects in northern China. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the 232MW circulating fluidized bed hot water boiler of the present invention;

[0029] Figure 2 Front view of a fully downward-sloping, stepless high-temperature adiabatic separator;

[0030] Figure 3 A top view of a fully downward-sloping, stepless high-temperature adiabatic separator;

[0031] Figure 4 for Figure 1 Sectional view along line AA;

[0032] Figure 5 Figure 4 M-direction view;

[0033] Figure 6 This is a schematic diagram of the water flow system layout.

[0034] In the diagram: 1. High-energy ignition device, 2. Full membrane wall structure equal pressure air chamber, 3. Primary air chamber, 4. Air distribution plate, 5. Coal feeding device in front of the furnace, 6. Boiler ash discharge device, 7. Secondary air box.

[0035] 8. Furnace chamber, 8-1. Upper dilute phase zone, 8-2. Lower dense phase zone, 8-3. Furnace chamber water-cooled screen;

[0036] 9. High-temperature insulated separator; 9-1. Inlet tangential acceleration section; 9-2. Straight cylinder; 9-3. Inverted cone; 9-4. Exhaust center cylinder.

[0037] 10. Riser;

[0038] 11. Return feeder; 111. Return feeder discharge pipe; 112. Return air chamber; 113. Diversion chamber; 114. Double return legs;

[0039] 13. Diverting flue; 14. Tail shaft flue; 15. Economizer; 16. Air preheater; 17. Compartmentalized outlet flue; 18. Boiler drum; 19. Centralized downcomer; 20. Distributed downcomer; 21. Front water-cooled wall inlet header; 22. Rear water-cooled wall inlet header; 23. Side water-cooled wall inlet header; 24. Water-cooled screen inlet header; 25. Water-cooled assembly header; 26. Economizer lower header; 27. Economizer outlet header.

[0040] 281. Recirculation pipe I, 282. Recirculation pipe II. Detailed Implementation

[0041] The following is a detailed description with reference to embodiments. Unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art.

[0042] Example 1, referring to Figure 1 This embodiment of a 232MW large-capacity circulating fluidized bed hot water boiler includes a high-energy ignition device 1, a full-membrane wall structure equal pressure air chamber 2, a primary air chamber 3, an air distribution plate 4, a coal feeding device 5, a boiler ash removal device 6, a secondary air box 7, a furnace 8, a high-temperature insulated separator 9, a riser 10, a return feeder 11, a diverting flue 13, a tail vertical flue 14, an economizer 15, an air preheater 16, and a compartmented outlet flue 17. The air distribution plate 4 is located at the bottom of the furnace 8 and is connected to the full-membrane wall structure equal pressure air chamber 2. 2. The primary air chamber 3 is connected to the rear side. The boiler ash removal device 6 passes through the full membrane wall structure equal pressure air chamber 2 and the air distribution plate 4 and is connected to the bottom of the furnace 8. The high-energy ignition device 1 is located on the rear side of the primary air chamber 3. The coal feeding device 5 is located at the lower part of the front wall of the furnace 8. The upper part of the coal feeding device 5 is connected to the coal feeder at the front of the furnace through a metal expansion joint. The secondary air box 7 is located around the lower part of the furnace 8 and is located above the coal feeding device 5. The secondary air box 7 is connected to the furnace 8 by multiple branch pipes distributed on the front and rear walls of the furnace 8. The upper part of the furnace 8... The exhaust end of the high-temperature insulated separator 9 is connected to the inlet end of the high-temperature insulated separator 9 via a non-metallic expansion joint. The lower part of the high-temperature insulated separator 9 is connected to the riser 10, and the lower part of the riser 10 is connected to the feed end of the return feeder 11. The discharge end of the return feeder 11 is connected to the lower part of the rear wall of the furnace 8. The exhaust end of the high-temperature insulated separator 9 is connected to the inlet of the diverting flue 13 via a non-metallic expansion joint. The outlet of the diverting flue 13 is connected to the inlet end of the tail vertical flue 14. The economizer 15 and the air preheater 16 are arranged sequentially from top to bottom in the tail vertical flue 16. The economizer 16 is connected to the lower part of the economizer 15 via a metal expansion joint and is connected to the outlet end of the tail vertical flue 14. The compartmented outlet flue 17 is connected to the outlet end of the air preheater 16 and serves as the boiler flue gas outlet. The high-temperature insulated separator 9 is a fully downward inclined stepless insulated separator. The return feeder 11 is a one-to-two dual-path return feed structure. The tubes of the economizer 15 and the air preheater 16 form the tail heating surface. The tail heating surface is a strong heat exchange self-cleaning tube bank with staggered arrangement. Each tube bank has wear-resistant protective tiles on the top layer and is equipped with a low-level in-furnace desulfurization and denitrification device.

[0043] The furnace is equipped with a slag cooler and an ash cooler, and the return feeder is equipped with an ash cooler. By adjusting the opening of each slag cooler and ash cooler, the thickness of the furnace material layer and the ratio of coarse and fine particles in the material layer can be effectively adjusted, ensuring that the boiler has excellent low-NOx combustion conditions. At the same time, the boiler can operate stably within the load range of 30-110%.

[0044] The boiler in this embodiment boasts a combustion efficiency of ≥99% and even higher thermal efficiency. The boiler's rated load test thermal efficiency reached 94.54%, far exceeding the national benchmark of 89%. Heating coal consumption was reduced to 35.82 kgce / GJ, saving 5%-10% of coal resources compared to older boilers. This industry-leading thermal efficiency saves 5650 tons of standard coal and 5 million RMB in fuel costs per heating season (152 days), while reducing CO2 emissions by 16100 tons. The boiler outlet utilizes a non-ash-accumulating, compartmented flue, employing pneumatic ash conveying to completely eliminate ash accumulation at the tail flue, replacing traditional manual ash removal. Initial NOx emissions are significantly lower, with a measured value of 63 mg / Nm³ (9% O2) during energy efficiency testing. This heating season, a single boiler reduced initial NOx emissions by 65 tons.

[0045] The furnace in this embodiment adopts a large-volume, fully sealed water-cooled wall structure to meet the combustion and heat exchange requirements of a 232MW large-capacity boiler. The boiler has a rated thermal power of 232MW and a thermal efficiency of ≥94%, NO X Initial emissions ≤80mg / Nm³ (6% O2, using lignite), single unit heats approximately 5 million square meters, suitable for large-scale urban centralized heating systems, applicable fuels: bituminous coal, lignite, low-quality coal, etc.

[0046] The tail heating surface adopts a high-heat-exchange self-cleaning tube bank. While increasing the flue gas velocity at the tail end, the staggered arrangement structure enhances the flue gas disturbance. The top layer of each tube bank is equipped with anti-wear protective tiles to reduce wear and reduce the frequency of soot blowing. By increasing the average flue gas velocity of the tube bank and optimizing the transverse and longitudinal pitch between tube banks, the heat transfer coefficient of the economizer is increased. At the same time, the disturbance of the flue gas through the economizer and air preheater is enhanced, giving it a self-cleaning function, effectively reducing the boiler outlet flue gas temperature, and significantly reducing the operating cost of the soot blower.

[0047] The desulfurization and denitrification adopts a low-position in-furnace coupled injection system. The denitrification is arranged in the furnace outlet area, and the desulfurization is arranged in the secondary air branch pipe, so as to realize the coordinated control of efficient desulfurization and low-NOx combustion in the furnace.

[0048] Example 2, Reference Figure 1 The furnace 8 includes an upper dilute phase zone 8-1, a lower dense phase zone 8-2, and a furnace water-cooled screen 8-3. The upper dilute phase zone 8-1 is located above the lower dense phase zone 8-2. The furnace water-cooled screen 8-3 is inserted inside the upper dilute phase zone 8-1. The width of the lowermost part of the lower dense phase zone 8-2 is the same as that of the upper dilute phase zone 8-1. The depth of the lower dense phase zone 8-2 is 0.35-0.4 times that of its uppermost part. The entire lower dense phase zone shrinks from top to bottom in the depth direction to 0.35-0.4 times its original size. The upper dilute phase zone 8-1 and the furnace water-cooled screen 8-3 are the main heat transfer areas. The flue gas velocity in the upper dilute phase zone 8-1 and the lower dense phase zone 8-2 is 4.6 m / s.

[0049] Reference Figure 2 and Figure 3 The high-temperature adiabatic separator 9 includes an inlet tangential acceleration section 9-1, a straight cylinder 9-2, an inverted cone 9-3, and an exhaust center cylinder 9-4. The inlet tangential acceleration section 9-1 is located at the upper side of the straight cylinder 9-2, serving as the inlet flue, and is connected to the upper exhaust end of the furnace 7 via a non-metallic expansion joint. The inverted cone 9-3 is located at the lower end of the straight cylinder 9-2, and the exhaust center cylinder 9-4 is located at the exhaust end of the top of the straight cylinder 9-2, serving as the outlet flue. The exhaust center cylinder 9-4 is eccentrically positioned relative to the centerline of the straight cylinder 9-2. The outlet end of the inlet tangential acceleration section 9-1 is positioned along the tangential direction of the straight cylinder 9-2 and inclined downwards at 9º-11º. The internal flow channel has no stepped structure, and the separation efficiency is ≥99.97%. The high-temperature insulated separator 9 is a high-temperature insulated large-diameter separator. The outer side of the straight cylinder 9-2 is provided with a heat insulation layer, and the flue gas rising velocity inside the separator is 4.5-5.5m / s.

[0050] Preferably, the height of the tangential acceleration section 9-1 is 0.8 times the diameter of the straight cylinder 9-2, the height of the straight cylinder 9-2 is 1.25 times its diameter, the throat velocity at the point where the tangential acceleration section 9-1 is tangent to the straight cylinder 9-2 is designed to be 28 m / s-28.5 m / s, the angle between the outer surface of the inverted cone 9-3 and the vertical direction is 12°, and the insertion depth of the exhaust center cylinder 9-4 is 0.35-0.4 times the height of the tangential acceleration section 9-1.

[0051] A fully downward-sloping, stepless high-temperature adiabatic separator, by appropriately increasing the inlet flue gas velocity and arranging a sufficiently long acceleration section in the inlet flue, achieves ultrafine circulating ash particles with a d50 of 10-15μm. This refines the particle size within the furnace, optimizes the flow pattern, reforms the atmosphere, forms particle clusters in the upper part of the furnace, increases interphase mass transfer resistance in the dense phase region, creates macroscopic oxygen enrichment and localized oxygen deficiency, and suppresses NOx formation. The separator adopts a fully downward-sloping, stepless adiabatic structure with a downward angle of 9°-11°, a smooth, stepless flow channel, and a separation efficiency ≥99.97%.

[0052] Better, refer to Figure 4 and Figure 5The return feeder 11 includes a return feeder discharge pipe 111, a return air chamber 112, a diversion chamber 113, and double return legs 114. The lower part of the riser 10 is connected to the return feeder discharge pipe 111. The return air chamber 112 is connected to the return feeder discharge pipe 111. The return air chamber 112 is connected to the diversion chamber 113. The diversion chamber 113 is connected to the double return legs 114. The discharge end of the return feeder 11 is connected to the lower part of the rear wall of the furnace 8 through the double return legs 12. Non-metallic expansion joints need to be installed inside the return legs 12. The return feeder 11 adopts a one-to-two dual-path return structure, with two return feeders per furnace, resulting in four symmetrically connected paths into the furnace. This ensures uniform return and avoids uneven bed temperature. The boiler body as a whole adopts a two-to-four return configuration, with each furnace equipped with two separators and two one-to-two return feeders. One separator corresponds to one one-to-two return feeder, and thus one separator corresponds to two furnace inlet return points. For circulating fluidized bed hot water boilers with large furnace cross-sections, this achieves uniform return and avoids uneven bed temperature and NO. X Increased production eliminates uneven burning and coking.

[0053] Preferably, the cross-sectional area of ​​the air distribution plate 4 is 0.35-0.4 times that of the furnace 8, and the air distribution plate adopts a large bell-shaped air cap with a flow velocity of 35-40 Nm / s in the small holes of the air cap and a resistance of 3000 Pa.

[0054] Preferably, the outlet ends of the secondary air box 7 are staggered on the front and rear walls of the furnace 8, requiring a staggered arrangement to achieve uniform ventilation, no dead corners, and elimination of oxygen-deficient core. The wind speed at the outlet end of the secondary air box 7 is 95 m / s, and the height between the outlet end of the secondary air box 7 and the air distribution plate 4 is 3.2-4.2 m.

[0055] Example 3, Reference Figure 6This boiler also includes a water flow system, comprising a centralized downcomer 19, a decentralized downcomer 20, a front water-cooled wall inlet header 21, a rear water-cooled wall inlet header 22, a side water-cooled wall inlet header 23, a water-cooled screen inlet header 24, a water-cooled collection header 25, an economizer lower header 26, and an economizer outlet header 27. The boiler return water end is the boiler drum 18. Water in the boiler drum 18 flows through the centralized downcomer 19 to the decentralized downcomer 20, and then enters the front water-cooled wall inlet header 21, the rear water-cooled wall inlet header 22, and the side water-cooled wall inlet headers 23 and 24. Water flows upward through the water-cooled wall 29 to its corresponding outlet header, and then enters the water-cooled collection header 25. After being collected in the water-cooled collection header 25, the water flows into the lower economizer header 26 in two directions. The economizer tube bank has a serpentine tube structure and flows upward in reverse to the economizer outlet header 27. The boiler drum 18 is connected to the water-cooled collection header 25 by a recirculation pipe I281, and the water-cooled collection header 25 is connected to the economizer outlet header 27 by a recirculation pipe II282. By employing uniformly distributed pipelines, reducing bends, and lowering water velocity, the water system achieves low-resistance performance, thereby reducing the power consumption of the circulating water pump. The boiler is equipped with a recirculation pipe I281 from the boiler drum 18 to the water-cooled collection box 25 and a recirculation pipe II282 from the water-cooled collection box 25 to the economizer outlet collection box 27. This ensures that the water-cooled system and the economizer 15 can be cooled by the water stored in the boiler drum during power outages, preventing accidents such as overheating and tube rupture. In this embodiment, power outage protection measures are implemented for both the furnace and the economizer. When the boiler suddenly loses power, all heating surface tubes of the boiler can be protected, achieving low-resistance power outage protection.

[0056] The specific implementation parameters of the 232MW large-capacity circulating fluidized bed hot water boiler described in any of the above embodiments are as follows:

[0057] 1. Rated thermal power: 232MW;

[0058] 2. Thermal efficiency test: ≥94%;

[0059] 3. Applicable fuels: bituminous coal, lignite, low-quality coal, etc.;

[0060] 4. Separator type: Fully downward inclined, stepless, high-temperature insulated separator with an inclination angle of 9.5°;

[0061] 5. Return material type: One-to-two dual-path return leg;

[0062] 6. Heating surface: High-efficiency heat exchange self-cleaning ash-collecting tubes;

[0063] 7. Low-level desulfurization and denitrification: In-furnace denitrification efficiency ≥80%, in-furnace desulfurization efficiency ≥95%;

[0064] 8. Environmental indicators: NO test XInitial emissions ≤80mg / Nm³ (6% O2, using lignite).

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions created by the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions created by the present invention without departing from the essence and scope of the technical solutions created by the present invention.

Claims

1. A 232MW large-capacity circulating fluidized bed hot water boiler, comprising a high-energy ignition device (1), a full-membrane wall structure isobaric air chamber (2), a primary air chamber (3), an air distribution plate (4), a coal feeding device in front of the furnace (5), a boiler ash discharge device (6), a secondary air box (7), a furnace (8), a high-temperature insulated separator (9), a riser (10), a return feeder (11), a diverting flue (13), a tail vertical shaft flue (14), an economizer (15), and an air preheater (16). 6) and compartmentalized outlet flue (17); the air distribution plate (4) is set at the bottom of the furnace (8), which is connected to the pressure equalization air chamber (2) of the full membrane wall structure. The rear side of the pressure equalization air chamber (2) of the full membrane wall structure is connected to the primary air chamber (3). The boiler slag discharge device (6) passes through the pressure equalization air chamber (2) of the full membrane wall structure and the air distribution plate (4) and is connected to the bottom of the furnace (8). The high-energy ignition device (1) is set at the rear side of the primary air chamber (3). The coal feeding device (5) is set in the furnace. (8) At the lower part of the front wall, the secondary air box (7) is set around the lower part of the furnace (8), and the secondary air box (7) is set on the upper side of the coal feeding device (5) in front of the furnace. The upper exhaust end of the furnace (8) is connected to the air inlet end of the high temperature insulated separator (9). The lower part of the high temperature insulated separator (9) is connected to the riser (10). The lower part of the riser (10) is connected to the feed end of the return feeder (11). The discharge end of the return feeder (11) is connected to the lower part of the rear wall of the furnace (8). The exhaust end of the high-temperature insulated separator (9) is connected to the inlet of the diverting flue (13), the outlet of the diverting flue (13) is connected to the inlet of the tail vertical shaft flue (14), the economizer (15) and the air preheater (16) are connected and arranged from top to bottom in the tail vertical shaft flue (14), the air preheater (16) is connected to the outlet of the tail vertical shaft flue (14), and the compartmented outlet flue (17) is connected to the outlet of the air preheater (16); its characteristic is: The high-temperature insulated separator is a fully inclined stepless insulated separator. The return feeder (11) is a one-to-two dual-path return feed structure. The tubes of the economizer (15) and the air preheater (16) form the tail heating surface. The tail heating surface is a strong heat exchange self-cleaning tube bank. The tube banks are arranged in a staggered manner, and the uppermost layer of each tube bank is equipped with anti-wear protective tiles.

2. The 232MW large-capacity circulating fluidized bed hot water boiler according to claim 1, characterized in that: The furnace (8) includes an upper dilute phase zone (8-1), a lower dense phase zone (8-2), and a furnace water-cooled screen (8-3). The upper dilute phase zone (8-1) is located above the lower dense phase zone (8-2). The furnace water-cooled screen (8-3) is inserted inside the upper dilute phase zone (8-1). The width of the lowermost part of the lower dense phase zone (8-2) is the same as that of the upper dilute phase zone (8-1). The depth of the lower dense phase zone (8-2) is 0.35-0.4 times that of its uppermost part. The upper dilute phase zone (8-1) and the furnace water-cooled screen (8-3) are the main heat transfer areas. The flue gas velocity in the upper dilute phase zone (8-1) and the lower dense phase zone (8-2) is 4.6 m / s.

3. The 232MW large-capacity circulating fluidized bed hot water boiler according to claim 1, characterized in that: The high-temperature insulated separator (9) includes an inlet tangential acceleration section (9-1), a straight cylinder (9-2), an inverted cone (9-3), and an exhaust center cylinder (9-4). The inlet tangential acceleration section (9-1) is located at the upper side of the straight cylinder (9-2) and is connected to the upper exhaust end of the furnace (7) through a non-metallic expansion joint. The inverted cone (9-3) is located at the lower end of the straight cylinder (9-2). The exhaust center cylinder (9-4) is located at the exhaust end of the top of the straight cylinder (9-2). The exhaust center cylinder (9-4) is eccentrically positioned with respect to the center line of the straight cylinder (9-2).

4. A 232MW large-capacity circulating fluidized bed hot water boiler according to claim 3, characterized in that, The outlet end of the inlet tangential acceleration section (9-1) is set along the tangential direction of the straight cylinder (9-2) and inclined downward by 9º-11º.

5. A 232MW large-capacity circulating fluidized bed hot water boiler according to claim 1, characterized in that, The flue gas rising velocity inside the high-temperature insulated separator (9) is 4.5-5.5 m / s.

6. A 232MW large-capacity circulating fluidized bed hot water boiler according to claim 3, characterized in that, The height of the tangential acceleration section (9-1) is 0.8 times the diameter of the straight cylinder (9-2), and the height of the straight cylinder (9-2) is 1.25 times its diameter. The throat velocity at the point where the tangential acceleration section (9-1) and the straight cylinder (9-2) are tangent is designed to be 28 m / s-28.5 m / s. The outer side of the inverted cone (9-3) has an angle of 12° with the vertical direction. The insertion depth of the exhaust center cylinder (9-4) is 0.35-0.4 times the height of the tangential acceleration section (9-1).

7. A 232MW large-capacity circulating fluidized bed hot water boiler according to claim 1, characterized in that, The cross-sectional area of ​​the air distribution plate (4) is 0.35-0.4 times that of the furnace (8). At the same time, a large bell-shaped air cap is used on the air distribution plate. The flow velocity of the small hole of the air cap is 35-40 Nm / s, and the resistance of the air cap is 3000 Pa.

8. A 232MW large-capacity circulating fluidized bed hot water boiler according to claim 1, characterized in that, The outlet ends of the secondary air box (7) are staggered on the front and rear walls of the furnace (8). The wind speed at the outlet end of the secondary air box (7) is 95 m / s, and the height between the outlet end of the secondary air box (7) and the air distribution plate (4) is 3.2-4.2 m.

9. A 232MW large-capacity circulating fluidized bed hot water boiler according to claim 1, characterized in that: The return feeder (11) includes a return feeder discharge pipe (111), a return air chamber (112), a diversion chamber (113), and double return legs (114). The upper end of the return feeder discharge pipe (111) is connected to the riser (10). The return air chamber (112) is connected to the return feeder discharge pipe (111). The return air chamber (112) is connected to the diversion chamber (113). The diversion chamber (113) is connected to the double return legs (114).

10. A 232MW large-capacity circulating fluidized bed hot water boiler according to claim 1, characterized in that, The boiler return water is the boiler drum (18). After flowing through the centralized downcomer (19) to the decentralized downcomer (20), it enters the front water-cooled wall inlet header (21), the rear water-cooled wall inlet header (22), the two side water-cooled wall inlet headers (23) and the water-cooled screen inlet header (24). The water flows upward through the water-cooled wall to its corresponding outlet header and then enters the water-cooled collection header (25). After being collected in the water-cooled collection header (25), it enters the lower economizer header (26) in two directions. The economizer tube bank has a serpentine tube structure and flows upward in reverse to the economizer outlet header (27). The boiler drum (18) is connected to the water-cooled collection header (25) by a recirculation pipe I (281), and the water-cooled collection header (25) is connected to the economizer outlet header (27) by a recirculation pipe II (282).

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