Solid waste combustion circulating fluidized bed boiler

Abstract

The utility model discloses a solid waste combustion circulating fluidized bed boiler which comprises a hearth body, an outer circulation loop, a water-cooling double flue, a secondary separator, a tail rear vertical shaft and an external air preheater, and the water-cooling double flue exchanges heat through a water-cooling evaporation screen of a water-cooling downstream front flue and a water-cooling tube bundle of a water-cooling upstream rear flue. The inlet smoke temperature of the medium and low temperature superheater heating surfaces of the water-cooling upstream rear flue is controlled to be less than or equal to 600 DEG C, so that the contamination and corrosion problems of the medium and low temperature superheaters on the convection heating surfaces are avoided; meanwhile, the hearth is of an empty hearth structure composed of water cooling walls, and the high-temperature corrosion risk can be avoided; the external air preheater can effectively avoid the problem of low-temperature corrosion; a secondary separator is connected behind the water-cooling double flues, so that the original dust of the boiler is further reduced, and the hazardous waste ratio is reduced; the device can effectively avoid the high and low temperature corrosion problem existing in solid waste fuel combustion, and long-period safe and stable operation of the boiler is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of combustion equipment, and more specifically, to a solid waste-burning circulating fluidized bed boiler. Technical Background

[0002] With the vigorous development of industry and the continuous improvement of people's living standards, the discharge of urban domestic garbage and industrial waste is increasing day by day, causing increasingly serious environmental problems. According to the "Law on the Prevention and Control of Environmental Pollution by Solid Waste", solid waste treatment needs to follow the "three principles", namely harmlessness, reduction and resource utilization, and adopt mature boiler incineration solid waste integrated treatment technology, which can not only burn out the toxic and harmful organic matter in the solid waste and reduce the volume, but also effectively utilize the calorific value of the solid waste for power generation and heating.

[0003] However, solid wastes such as papermaking light residue, papermaking sludge, general industrial solid waste from textiles, sludge generated after urban sewage treatment, and agricultural and forestry wastes have the following characteristics: (1) low calorific value, complex composition, and large volatility, making it difficult to achieve long-term safe and stable operation using conventional coal-fired boilers; (2) high water content, containing corrosive components such as Cl and S and low-melting-point alkali metal components such as Na and K. The flue gas generated after combustion contains corrosive gases such as HCl, SO2, H2S, and volatilized alkali metal gases, which are easy to condense into liquid or solid when encountering a relatively low temperature heating surface, easily causing dust accumulation, contamination, and corrosion of the heating surface; (3) impurities such as iron wire, stones, and glass slag that are inevitably carried by the fuel entering the furnace. If they are not discharged from the furnace in time, they will continue to accumulate as the operating time increases. The iron wire in the bed is easy to tangle and difficult to discharge, and the glass slag and other ash have low melting points and are easy to clog the wind hood, shortening the operating cycle; (4) The emission of pollutants such as CO is easy to exceed the standard and cannot meet the requirements of national environmental protection standards.

[0004] In response to the above problems, researchers have also proposed different solutions and applied for some solid waste furnace patents. For example, the utility model patent with publication number CN213066123U proposes a circulating fluidized bed incineration boiler for burning solid waste. This patent focuses on technical measures to prevent high-temperature corrosion, but the air preheater's low-temperature corrosion protection solution still uses stainless steel or enameled tubes commonly used in conventional coal-fired CFB boilers. Its anti-corrosion effect has been verified to be poor in engineering. At the same time, this patent does not consider the optimization of the boiler's original dust emissions.

[0005] For example, the invention patent with publication number CN112161274A proposes a large-capacity circulating fluidized bed garbage combustion boiler. This patent only avoids high-temperature corrosion by not arranging a screen-type heating surface in the furnace. The tail flue and heating surface layout still adopt the layout scheme of a conventional coal-fired CFB boiler, and cannot effectively solve the high and low temperature corrosion problems existing in burning garbage and solid waste; for example, the invention patent with publication number CN117346136A proposes a circulating fluidized bed boiler for burning waste and its operation method, which combines a high-temperature superheater, a high-temperature reheater and a cyclone separator to improve the corrosion problem of the high-temperature heating surface and improve the steam parameters. However, the actual heating surface of the cyclone separator is limited, and refractory castables are laid, so the heat transfer coefficient is low. When the superheated steam temperature and the reheated steam temperature are relatively high, the heat absorption ratio is far from meeting the heat absorption ratio requirements of the high-temperature superheater and the high-temperature reheater. Utility Model Content

[0006] In view of the above, the present application provides a solid waste-fired circulating fluidized bed boiler that can not only meet the heat exchange requirements, but also effectively avoid the high and low temperature corrosion problems of solid waste fuels.

[0007] The present application provides a solid waste burning circulating fluidized bed boiler, comprising a furnace body, an external circulation loop, and a tail rear shaft; wherein the furnace body comprises a furnace, a feed port, a water-cooled air chamber, an air distribution plate, a slag discharge pipe, and a secondary air port; the external circulation loop comprises a primary separator, a return material riser, a fluidized heat exchange return material, and a high-temperature superheater; the tail rear shaft comprises a rear shaft flue, a flue gas cooler, an economizer, and an outlet flue; it also comprises a water-cooled double flue, a secondary separator, and an external air preheater.

[0008] The water-cooled double flue includes a water-cooled downward front flue, a water-cooled upward rear flue, a water-cooled evaporation screen, a water-cooled tube bundle, a low-temperature superheater, and a medium-temperature superheater; the water-cooled downward front flue is connected to the top of the first-stage separator through the flue at its upper end, the water-cooled evaporation screen is arranged in the water-cooled downward front flue, and a hydraulic soot blowing device is arranged at the top of the water-cooled downward front flue; the water-cooled upward rear flue is arranged with a water-cooled tube bundle, a medium-temperature superheater, and a low-temperature superheater from bottom to top.

[0009] The water-cooled double flue adopts a water-cooled wall structure to reduce the wall temperature and corrosion. A water-cooled evaporation screen is arranged in the water-cooled downward flue. Casting materials or spray anti-corrosion materials are laid around the upper part of the water-cooled downward flue and the upper part of the water-cooled evaporation screen to avoid high-temperature corrosion. A hydraulic soot blowing device is arranged in the water-cooled downward flue. The hydraulic soot blowing device can make the slag contaminated on the tube wall expand and break and fall off during the process of rapid expansion of water heated after the spray water penetrates into the interior, and then be discharged through the ash conveying device to the ash storage; the water-cooled upward rear flue is arranged with a water-cooled tube bundle, a medium-temperature superheater, and a low-temperature superheater from bottom to top. Through the heat exchange between the water-cooled downward flue and the water-cooled tube bundle, the inlet flue gas temperature of the heating surface of the medium-temperature superheater and the low-temperature superheater is controlled to be ≤600℃, avoiding the contamination and corrosion of the convective heating surface of the medium-temperature superheater and the low-temperature superheater.

[0010] The water-cooled ascending flue is also connected to the upper end of the secondary separator through the flue at its upper end, the bottom end of the secondary separator is connected to the ash pump, and the secondary separator is connected to the upper end of the rear shaft flue through the flue at its top.

[0011] The secondary separator is an adiabatic structure, with its inlet flue gas velocity and cross-sectional rising velocity set at 20~30m / s and 4~7m / s respectively to ensure separation efficiency. At the same time, high-efficiency cyclone dust removal is used to further reduce the original dust of the boiler and the proportion of hazardous waste. The separated dust enters the ash storage through the ash pump.

[0012] The external air preheater includes an external secondary air preheater, an external primary air preheater, a secondary air heat exchange tube bundle, a primary air heat exchange tube bundle, a hot secondary air duct, a hot primary air duct, an ignition air duct, and an ignition burner; the external secondary air preheater is connected to the secondary air box through the hot secondary air duct, and the secondary air box is connected to the secondary air outlet; the external primary air preheater is connected to the ignition air duct through the hot primary air duct; the external secondary air preheater is arranged with a secondary air heat exchange tube bundle, and the external primary air preheater is arranged with a primary air heat exchange tube bundle; and an ignition burner is arranged at the connection between the hot primary air duct and the ignition air duct.

[0013] The external air preheater adopts a water heat medium air preheater structure, using boiler feed water as the heat transfer medium. All or part of the boiler feed water enters the air preheater to heat the air, and the outlet water temperature is reduced to about 100°C. It then enters the flue gas cooler to cool the flue gas to meet the exhaust temperature requirements. The water at the outlet of the flue gas cooler is mixed with the water that has not passed through the air preheater and then enters the economizer. The air does not directly exchange heat with the flue gas. The outlet water temperature of the air preheater is adjusted by adjusting the water flow entering the air preheater to ensure that the water inlet temperature of the flue gas cooler is stable and controllable, which can effectively ensure that the wall temperature of the heat exchange tube of the flue gas cooler is higher than the acid dew point temperature, and can effectively avoid low-temperature corrosion problems.

[0014] The furnace is composed of a full-membrane water-cooled wall structure, which is completely covered by castables. There are no other screen-type heating surfaces in the furnace. It is an empty furnace structure, which can avoid the risk of high-temperature corrosion. At the same time, the fluidization velocity in the furnace is guaranteed to be 4~5m / s and the combustion temperature is 860℃~900℃, ensuring that harmful substances such as dioxins are burned out.

[0015] A feeding port is arranged on the front wall at the lower end of the furnace, and secondary air inlets are arranged on the front and rear walls at the lower end; an air distribution plate is arranged at the bottom of the furnace, and a water-cooled air chamber is arranged below the air distribution plate; a slag discharge ditch is arranged in the middle of the air distribution plate, and a slag discharge pipe is connected below the slag discharge ditch, and the slag discharge pipe is located in the middle of the water-cooled air chamber.

[0016] The air distribution plate is inclined from the edge of the furnace body to the middle. It is a stepped inclined air distribution device composed of directional air hoods, and the directional air hoods are all facing the middle of the air distribution plate.

[0017] Impurities such as iron wire, stones, glass slag, etc. carried into the furnace by solid waste fuel, as well as coarse particulate matter generated after combustion, are moved to the slag discharge groove in the middle of the air distribution plate under the action of a large amount of circulating bed material in the dense phase area of the furnace and the directional air hood arranged on the air distribution plate, and are discharged from the furnace through the slag discharge pipe, which can discharge impurities in a timely and effective manner, and continuously discharge slag during the operation of the solid waste circulating fluidized bed boiler to ensure the continuity of slag discharge. The discharged bed material can be returned to the furnace after cooling and screening to maintain the stability of the furnace bed pressure and bed temperature.

[0018] The first-stage separator is connected to the furnace through the flue at the upper end, and its bottom end is connected to the return material riser. The bottom end of the return material riser is connected to the fluidized heat exchange return material. A high-temperature superheater is arranged in the fluidized heat exchange return material. The fluidized heat exchange return material is also connected to the lower end of the furnace through the return channel.

[0019] The first-stage separator adopts cooling type or adiabatic type according to the fuel conditions, and its inlet smoke velocity and cross-section rising velocity are set to 20~30m / s and 5~8m / s respectively to ensure the gas-solid separation efficiency; the fluidized heat exchange re-materializer is a combination of a re-materializer and an external bed, including a double re-materializer corresponding to one external bed or a re-materializer corresponding to one external bed. The re-materializer and the external bed are merged into a large container, and the high-temperature superheater is arranged in the large container with a buried pipe structure to ensure the effective layout space of the superheater and meet the heat exchange requirements of the superheater; at the same time, the interior of the fluidized heat exchange re-materializer is also divided into a re-materializer area, an external bed area and an ash channel by partition walls. By adjusting the air volume in different areas, the amount of high-temperature ash entering the external bed is controlled to achieve the regulation of the superheated steam temperature.

[0020] The rear vertical flue is equipped with economizer, flue gas cooler and outlet flue from top to bottom.

[0021] In summary, the device of the present application can ensure the complete combustion of solid waste fuel, so that the emission concentrations of pollutants such as dioxins, CO, and dust are better than the emission standards. It can effectively avoid the high and low temperature corrosion problems of burning solid waste fuel while meeting the heat exchange requirements of the boiler. At the same time, it can promptly remove impurities such as iron wire, stones, and glass slag brought into the furnace by the solid waste fuel, thereby ensuring the long-term safe and stable operation of the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural diagram of the solid waste burning circulating fluidized bed boiler of this application.

[0023] The markings in the figure are: 1-steam drum, 2-furnace, 3-primary separator, 4-return material standpipe, 5-fluidized heat exchange return material, 6-water-cooled downward front flue, 7-water-cooled upward rear flue, 8-secondary separator, 9-rear shaft flue, 10-external secondary air preheater, 11-external primary air preheater, 12-secondary air heat exchange tube bundle, 13-primary air heat exchange tube bundle, 14-smoke cooler, 15-economizer, 16-water-cooled evaporator screen, 17-water-cooled tube bundle, 18-low-temperature superheater, 19-medium-temperature superheater, 20-high-temperature superheater, 21-feeding port, 22-water-cooled air chamber, 23-air distribution plate, 24-slag discharge pipe, 25-hot secondary air duct, 26-secondary air duct, 27-hot primary air duct, 28-ignition air duct, 29-ignition burner, 30-hydraulic soot blowing device, 31-ash conveying pump, 32-outlet flue. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in more detail below. The present application can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided for a more thorough and complete understanding of the present application. It should be understood that the embodiments of the present application are intended for exemplary purposes only and are not intended to limit the scope of protection of the present application.

[0025] The present application is further described in detail below with reference to the accompanying drawings and embodiments:

[0026] As shown in the accompanying drawings, a solid waste-fired circulating fluidized bed boiler used in this embodiment has an external primary air preheater 11 connected to a water-cooled air chamber 22 through a hot primary air duct 27 and an ignition air duct 28 in sequence. An air distribution plate 23 is arranged above the water-cooled air chamber 22, a slag discharge ditch is arranged in the middle of the air distribution plate 23, and a slag discharge pipe 24 is connected to the bottom of the slag discharge ditch. The slag discharge pipe 24 is located in the middle of the water-cooled air chamber 22; the air distribution plate 23 is arranged at the bottom of the furnace 2, and the front wall of the lower end of the furnace 2 is provided with a slag discharge pipe 24 ... A feed port 21 is provided, and secondary air ports 26 are provided on the front and rear walls of the lower end. The secondary air ports 26 are connected to the secondary air blowbox, which is connected to the external secondary air preheater 10 via a hot secondary air duct 25. The external primary air preheater 11 and the external secondary air preheater 10 are respectively provided with a primary air heat exchange tube bundle 13 and a secondary air heat exchange tube bundle 12. An ignition burner 29 is provided at the connection between the hot primary air duct 27 and the ignition air duct 28.

[0027] A steam drum 1 is arranged above the furnace 2. The furnace 2 is connected to the upper end of the first-stage separator 3 through the flue on the upper rear wall. The bottom end of the first-stage separator 3 is connected to the return material riser 4. The bottom end of the return material riser 4 is connected to the fluidized heat exchange return material 5. A high-temperature superheater 20 is arranged in the fluidized heat exchange return material 5. The fluidized heat exchange return material 5 is also connected to the lower end of the furnace 2 through a return material channel. The first-stage separator 3 adopts a cooling type or an adiabatic type. The fluidized heat exchange return material 5 is a combination of a return material and an external bed, including a double return material corresponding to one external bed or a return material corresponding to one external bed. The high-temperature superheater is arranged in the fluidized heat exchange return material 5 with an buried pipe structure. The interior of the fluidized heat exchange return material 5 is also divided into a return material area, an external bed area and an ash channel by a partition wall.

[0028] The first-stage separator 3 is connected to the upper end of the water-cooled downward front flue 6 through the flue at the top. A water-cooled evaporation screen 16 is arranged in the water-cooled downward front flue 6, and a hydraulic soot blowing device 30 is arranged at the top of the water-cooled downward front flue 6; the water-cooled upward rear flue 7 is arranged with a water-cooled tube bundle 17, a medium-temperature superheater 19, and a low-temperature superheater 18 from bottom to top; the water-cooled double flue 7 is connected to the upper end of the second-stage separator 8 through the flue at the upper end, and the bottom end of the second-stage separator 8 is connected to the ash pump 31; the second-stage separator 8 is connected to the upper end of the rear vertical shaft flue 9 through the flue outlet at the top, and the rear vertical shaft flue 9 is arranged with an economizer 15, a flue gas cooler 14 and an outlet flue 32 from top to bottom.

[0029] Example:

[0030] The air from the primary fan passes through the external primary air preheater 11, and then passes through the hot primary air duct 27 and the ignition air duct 28 under the bed into the water-cooled air chamber 22 at the bottom of the furnace, and then enters the furnace 2 through the hood on the air distribution plate 23, so that the bed material is evenly fluidized and forms a gas-solid two-phase flow passing upward through the furnace 2. In order to ensure sufficient combustion residence time, the cross-sectional velocity of the furnace 2 is set to 4~5m / s; the fuel after crushing and sorting pretreatment, with its longest side not exceeding 80mm, is fed into the dense phase area at the bottom of the furnace 2 from the feed port 21, fully mixed with the air and the fluidized high-temperature bed material, and ignited and burned; at the same time, the air from the secondary fan is heated by the external secondary air preheater 10, and then passes through the hot secondary air duct 25 It enters the secondary air box and is sent into the furnace 2 in sections through the secondary air duct 26, which supplements sufficient combustion air for the solid waste fuel combustion and causes strong disturbance in the flow field in the furnace, so that the solid waste fuel is fully mixed with the high-temperature bed material and combustion air, ensuring the burnout of the solid waste fuel and reducing the generation of pollutants such as CO and dioxins; and by arranging a suitable water-cooled wall heating surface in the furnace 2, laying a reliable high-thermal conductivity anti-corrosion castable, and controlling the appropriate primary and secondary air ratio, the temperature of the furnace 2 is controlled at 860℃~900℃ through the matching of combustion and heat transfer, and selecting a reasonable height design of the furnace 2 to ensure that the solid waste flue gas stays in the temperature range above 860℃ in the furnace for more than 2s, meeting the requirements of relevant environmental protection standards.

[0031] Impurities such as iron wire, stones, glass slag, etc. carried into the furnace by solid waste fuel, as well as coarse particulate matter generated after combustion, are moved to the slag discharge ditch located in the middle of the air distribution plate 23 under the action of a large amount of circulating bed material in the dense phase area and the directional wind hood arranged on the air distribution plate 23, and then discharged from the furnace 2 through the slag discharge pipe 24. In order to ensure the continuity of impurity removal, the slag discharge system maintains continuous operation during operation. The discharged bed material can be returned to the furnace 2 after cooling and screening to maintain the stability of the bed pressure and bed temperature of the furnace 2.

[0032] The flue gas generated by combustion carries a large amount of bed material and turns through the furnace top, enters the first-level separator 3 through the flue located at the upper end of the furnace 2 for gas-solid separation. The first-level separator 3 of this embodiment adopts a cooling type. In order to ensure the separation efficiency, the flue gas velocity at the separator inlet is set to 20~30m / s, and the cross-sectional rising speed of the separator is 5~8m / s; most of the particles are separated and captured by the first-level separator 3 and then introduced into the fluidized heat exchange return material 5 through the return material riser 4. A part of the high-temperature ash is returned to the furnace 2 after heat exchange with the high-temperature superheater 20 arranged in the fluidized heat exchange return material 5, and the remaining high-temperature ash is directly returned to the furnace 2; the high-temperature superheater 20 controls the amount of high-temperature ash entering the external bed through the arrangement of the external bed, realizes the regulation of the superheated steam temperature, reasonably avoids corrosive high-temperature flue gas, and effectively avoids the occurrence of high-temperature corrosion problems.

[0033] The flue gas containing a small amount of fly ash after separation by the primary separator 3 enters the water-cooled down-flow front flue 6 through the flue at the top of the primary separator 3. A water-cooled evaporation screen 16 is arranged in the water-cooled down-flow front flue 6. Casting material or spraying is laid around the upper part of the water-cooled down-flow front flue 6 and the upper part of the water-cooled evaporation screen 16 to prevent high-temperature corrosion. The flue gas releases heat to the membrane wall and water-cooled screen around the flue. At the flue outlet at the bottom of the water-cooled down-flow front flue 6, the flue temperature drops to about 600~700℃. In order to ensure the long-term operation of the unit, a hydraulic soot blowing device 30 is provided at the top of the water-cooled down-flow front flue 6. The hydraulic soot blowing device can make the slag contaminated on the pipe wall be sprayed with water. After entering the flue, the water is heated and expands rapidly, causing the slag to expand in volume and then break and fall off, and then be discharged through the ash conveying device and transported to the ash and slag storage; the flue gas then enters the water-cooled ascending rear flue 7 in sequence, and a water-cooled tube bundle 17 is first arranged in the water-cooled ascending rear flue 7. After the flue gas passes through the water-cooled tube bundle 17, the flue gas temperature drops to no more than 600°C. Then, after the flue gas passes through the heating surfaces of the medium-temperature superheater 19 and the low-temperature superheater 18 arranged in the water-cooled ascending rear flue 7, the flue gas temperature will drop to below 400°C. However, when the flue gas reaches the flue outlet of the water-cooled descending front flue 6, its flue gas temperature has dropped to no more than 600°C, and the water-cooled tube bundle 17 will not be arranged.

[0034] The flue gas carries a small amount of fly ash and enters the secondary separator 8 through the flue at the top of the water-cooled ascending flue 7. It is further separated and dusted by the secondary separator 8. The flue gas velocity at the separator inlet is set to 20-30 m / s, the cross-sectional rising speed of the separator is set to 4-7 m / s, and the dust concentration at the lower end outlet of the secondary separator 8 is controlled to be less than 20 g / Nm 3 The separated and captured dust is transported to the ash storage through the ash conveying pump 31; the flue gas after dust removal enters the rear vertical shaft flue 9 with an adiabatic structure through the flue at the top of the secondary separator 8, and passes through the economizer 15 and the flue gas cooler 14 in the direction of flue gas flow. The water inlet temperature of the flue gas cooler 14 is relatively high and stable and controllable, ensuring that the wall temperature of the heat exchange tube of the flue gas cooler 14 is higher than the acid dew point temperature, effectively avoiding low-temperature corrosion of the flue gas cooler 14. After the flue gas exchanges heat in the rear vertical shaft flue 9, the flue gas temperature drops to no more than 180°C and is discharged from the outlet flue 32, thus realizing the complete combustion utilization of the waste.

[0035] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited to this. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A solid waste burning circulating fluidized bed boiler, comprising a furnace body, an external circulation loop, and a tail rear shaft; wherein the furnace body comprises a furnace (2), a feed port (21), a water-cooled air chamber (22), an air distribution plate (23), a slag discharge pipe (24), and a secondary air port (26); the external circulation loop comprises a primary separator (3), a return material vertical pipe (4), a fluidized heat exchange return material (5), and a high-temperature superheater (20); the tail rear shaft comprises a rear shaft flue (9), a flue gas cooler (14), an economizer (15), and an outlet flue (32); and is characterized in that: It also includes a water-cooled double flue, a secondary separator (8) and an external air preheater; The water-cooled double flue comprises a water-cooled down-flow front flue (6), a water-cooled up-flow rear flue (7), a water-cooled evaporation screen (16), a water-cooled tube bundle (17), a low-temperature superheater (18), and a medium-temperature superheater (19); wherein the water-cooled down-flow front flue (6) is connected to the top of the first-stage separator (3) through the flue at its upper end, the water-cooled evaporation screen (16) is arranged in the water-cooled down-flow front flue (6), and a hydraulic soot blowing device (30) is arranged at the top of the water-cooled down-flow front flue (6); wherein the water-cooled up-flow rear flue (7) is sequentially arranged with a water-cooled tube bundle (17), a medium-temperature superheater (19), and a low-temperature superheater (18) from bottom to top; The water-cooled ascending rear flue (7) is connected to the upper end of the secondary separator (8) through the flue at its upper end, the bottom end of the secondary separator (8) is connected to the ash conveying pump (31), and the secondary separator (8) is connected to the upper end of the rear shaft flue (9) through the flue at its top end; The external air preheater comprises an external secondary air preheater (10), an external primary air preheater (11), a secondary air heat exchange tube bundle (12), a primary air heat exchange tube bundle (13), a hot secondary air duct (25), a hot primary air duct (27), an ignition air duct (28), and an ignition burner (29); wherein the external secondary air preheater (10) is connected to the secondary air blower through the hot secondary air duct (25), and the secondary air blower is connected to the secondary air outlet (26); the external primary air preheater (11) is connected to the ignition air duct (28) through the hot primary air duct (27); wherein the secondary air heat exchange tube bundle (12) is arranged in the external secondary air preheater (10), and the primary air heat exchange tube bundle (13) is arranged in the external primary air preheater (11).

2. The solid waste-fired circulating fluidized bed boiler according to claim 1, characterized in that: An ignition burner (29) is arranged at the connection between the hot primary air duct (27) and the ignition air duct (28).

3. The solid waste-fired circulating fluidized bed boiler according to claim 1, characterized in that: A feed port (21) is arranged on the front wall of the lower end of the furnace (2), and secondary air ports (26) are arranged on the front and rear walls of the lower end; an air distribution plate (23) is arranged at the bottom of the furnace (2), and a water-cooled air chamber (22) is arranged below the air distribution plate (23); a slag discharge ditch is arranged in the middle of the air distribution plate (23), and a slag discharge pipe (24) is connected below the slag discharge ditch, and the slag discharge pipe (24) is located in the middle of the water-cooled air chamber (22).

4. A solid waste burning circulating fluidized bed boiler according to any one of claims 1 to 3, characterized in that: The furnace (2) is composed of a full-membrane water-cooled wall structure, the water-cooled wall is completely covered by castables, and no other screen-type heating surfaces are arranged in the furnace, which is an empty furnace structure.

5. A solid waste burning circulating fluidized bed boiler according to any one of claims 1 to 3, characterized in that: The air distribution plate (23) is inclined from the edge of the furnace body toward the middle, and is a stepped inclined air distribution device composed of directional air hoods, and the directional air hoods are all oriented toward the middle of the air distribution plate (23).

6. The solid waste-fired circulating fluidized bed boiler according to claim 1, characterized in that: The primary separator (3) is connected to the furnace (2) via a flue at the upper end, and its bottom end is connected to a return material riser (4). The bottom end of the return material riser (4) is connected to a fluidized heat exchange return material (5). A high-temperature superheater (20) is arranged in the fluidized heat exchange return material (5). The fluidized heat exchange return material (5) is also connected to the lower end of the furnace (2) via a return material channel.

7. The solid waste-fired circulating fluidized bed boiler according to claim 6, characterized in that: The first-stage separator (3) is of cooling type or adiabatic type, and the inlet smoke velocity and cross-sectional rising velocity are 20-30 m / s and 5-8 m / s respectively.

8. The solid waste-fired circulating fluidized bed boiler according to claim 6, characterized in that: The fluidized heat exchange recycler (5) is a recycler and an external bed combined into one, including two recyclers corresponding to one external bed or one recycler corresponding to one external bed; the high-temperature superheater is arranged in the fluidized heat exchange recycler (5) in a buried pipe structure; the interior of the fluidized heat exchange recycler (5) is further divided into a recycler area, an external bed area and an ash channel by a partition wall.

9. The solid waste-fired circulating fluidized bed boiler according to claim 1, characterized in that: The rear vertical shaft flue (9) is sequentially arranged with an economizer (15), a flue gas cooler (14) and an outlet flue (32) from top to bottom.

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