A circulating fluidized bed boiler structure with a cooling chamber for burning mixed fuels

Abstract

The present invention relates to a circulating fluidized bed boiler structure with a cooling chamber that burns a mixture of chicken manure and biomass. Chicken manure, as a fuel for a fluidized bed boiler, has the characteristics of low calorific value, high water content, strong fly ash adhesion, and high corrosiveness. Conventional biomass circulating fluidized bed boilers can no longer fully meet the requirements for the use of this fuel. The present invention redesigns the various heating surfaces of the boiler based on the characteristics of the fuel. A screen-type superheater is arranged in the furnace as a high-temperature superheater, a cooling chamber wall is provided after the steam-cooled separator, a low-temperature superheater and a medium-temperature superheater are arranged in the cooling chamber wall, and an economizer and an air preheater are arranged in the tail flue. Ash cleaning is taken into consideration for all levels of heating surfaces. The present invention improves the combustion heat energy utilization rate of a fluidized bed boiler that burns a mixture of chicken manure and biomass, reduces the wear of the heating surface and alkali metal corrosion caused by high-speed and high-temperature flue gas, and enhances the wear resistance of the wall.

Description

Technical Field

[0001] The invention belongs to the technical field of circulating fluidized bed boilers, and in particular relates to a circulating fluidized bed boiler structure with a cooling chamber and burning mixed fuels. Background Art

[0002] As my country's economy reaches a new level, the demand for chicken is increasing. my country has become the country with the largest number of chickens in the world. At the same time, the problem of chicken manure disposal has been a constant concern. If handled well, chicken manure can become a resource that can be utilized by people. However, if handled poorly, it not only wastes resources but also pollutes the environment. Therefore, how to more effectively treat chicken manure has become a problem that needs to be urgently addressed.

[0003] Chicken manure and biomass mixed fuel, used as a fluidized bed boiler fuel, has the characteristics of low calorific value, high water content, strong fly ash cohesion, and high corrosiveness. Conventional biomass circulating fluidized bed boilers no longer fully meet the requirements for using this fuel. The present invention aims to overcome the shortcomings of the existing technology and provide a circulating fluidized bed boiler with a cooling chamber that burns chicken manure and biomass mixed fuel, which has a compact structure, sufficient combustion, and high combustion heat energy conversion rate.

[0004] In this context, a circulating fluidized bed boiler suitable for burning a mixture of chicken manure and biomass has been developed, taking into account the characteristics of chicken manure. Specifically, a heating surface arrangement structure of a circulating fluidized bed boiler with a cooling chamber for burning a mixture of chicken manure and biomass has been developed. Summary of the Invention

[0005] The present invention aims to process large quantities of chicken manure that the environment cannot digest on its own. Based on existing biomass circulating fluidized bed boilers, this one is developed to burn a mixture of chicken manure and biomass. Its rational boiler structure eliminates the adverse effects of burning chicken manure on the boiler, allowing for extended continuous operation and high combustion efficiency.

[0006] A circulating fluidized bed boiler structure for burning mixed fuels with a cooling chamber is provided, comprising: a steam drum, a furnace, a water-cooled air chamber, a superheating system, a return device, a downcomer, a top connecting pipe, an upper economizer, an air preheater, a lower economizer, a feed interface, and an ignition device, characterized in that:

[0007] A water-cooled air chamber is set at the bottom of the furnace, and a low-nitrogen combustion air hood is arranged on the water-cooled air chamber. Three layers of secondary air ducts are arranged on the front and rear walls of the dense phase area of ​​the furnace, and a feeding interface is arranged on the front wall, the height of which is greater than the zero-pressure area of ​​the furnace.

[0008] The furnace forms a natural circulation with the steam drum through the downcomer and top connecting pipe;

[0009] The superheating system includes a steam-cooled separator, a low-temperature superheater, a first-stage water spray desuperheater, a medium-temperature superheater, a second-stage water spray desuperheater, and a platen superheater. The low-temperature superheater and the medium-temperature superheater are arranged from bottom to top in the smoke chamber behind the cooling chamber, with a first-stage water spray desuperheater located between the low-temperature and medium-temperature superheaters. The outlet pipe of the medium-temperature superheater is connected to the second-stage water spray desuperheater, and the platen superheater is arranged inside the furnace.

[0010] The air preheater is arranged in multiple stages, including a high-temperature air preheater and a low-temperature air preheater. The high-temperature air preheater is arranged between the upper economizer and the lower economizer. The tail shaft flue is arranged from top to bottom with the upper economizer, high-temperature air preheater, lower economizer, low-temperature air preheater, and air preheater ash hopper.

[0011] A U-shaped channel cooling chamber wall is set between the steam-cooled separator and the upper economizer. The U-shaped channel cooling chamber wall includes a front wall, a rear wall, a side wall, and a partition wall. The U-shaped channel cooling chamber wall passes through a downcomer and a top connecting pipe to the steam drum to form a natural circulation. A spray system is arranged on the top of the smoke chamber in front of the U-shaped channel cooling chamber wall, and a cooling chamber ash hopper is arranged at the bottom.

[0012] The medium-temperature superheater and the upper economizer are connected through a flue connected to the cooling chamber wall.

[0013] Furthermore, long telescopic steam soot blowers are arranged in the low-temperature superheater and medium-temperature superheater areas, fixed rotary steam soot blowers are arranged in the upper economizer and lower economizer areas; shock wave soot blowers are arranged in the high-temperature air preheater and low-temperature air preheater areas.

[0014] Furthermore, the front wrapping wall, the rear wrapping wall, the side wrapping wall and the partition wrapping wall are all membrane water-cooled wall structures, which together form a U-shaped channel.

[0015] Furthermore, the low-temperature superheater, medium-temperature superheater, upper economizer, high-temperature air preheater, lower economizer and low-temperature air preheater are all arranged in series with a large intercept. The primary and secondary air duct boxes of the high-temperature air preheater and the low-temperature air preheater are all made of enameled pipe materials, and the pipe boxes are arranged independently.

[0016] Furthermore, compressed air blowing devices are respectively arranged on the vertical pipes of the return device and the cooling chamber ash hopper.

[0017] Furthermore, an SNCR nozzle is arranged at the inlet of the steam-cooled separator, and a large-diameter adiabatic slag discharge port is arranged at the bottom of the furnace.

[0018] Furthermore, refractory castables are laid on the top and outlet of the furnace, refractory castables are laid in the steam-cooled separator, and refractory castables are laid at the front smoke chamber inlet and top, the bottom turn, and the rear smoke chamber outlet and top of the U-shaped channel cooling chamber wall; refractory castables are laid at the L-shaped bend at the lower part of the screen superheater and on the water-cooled membrane wall at the screen superheater wall.

[0019] Furthermore, a sprinkler system is arranged on the top of the smoke chamber in front of the U-shaped channel cooling chamber wall, and a cooling chamber ash hopper is arranged on the bottom.

[0020] The technical solution of the present invention is further described in detail below through the accompanying drawings and specific embodiments. Beneficial effects

[0021] The furnace is tall, with a large cross-sectional area, providing ample heating surface and low flow rates, keeping the combustion temperature below 800°C. A U-shaped cooling chamber wall is installed between the steam-cooled separator and the upstream economizer. The cooling chamber features a membrane-type water-cooled wall structure, which can quickly reduce the flue gas temperature from 800°C to below 650°C, effectively lowering the flue gas temperature passing through the superheater, preventing excessive superheater tube wall temperatures and high-temperature corrosion. Furthermore, an insulated cooling chamber ash hopper, located at the bottom of the U-shaped cooling chamber wall, collects large amounts of flue dust, significantly reducing dust accumulation and corrosion in the superheater. A spray system is installed at the top of the flue chamber in front of the U-shaped cooling chamber wall to regulate the flue gas temperature entering the low-temperature superheater, thereby reducing the tube wall temperature. This prevents high-temperature flue gas corrosion and ash sticking to the tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a front view of a structural schematic diagram of an embodiment of the present invention.

[0023] Figure 2 It is a left view of the structural schematic diagram of an embodiment of the present invention.

[0024] Figure 3 It is a right view of the structural diagram of an embodiment of the present invention.

[0025] Figure 4 It is a top view of the structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, the common implementation methods of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] Furthermore, in the description of the present invention, “a plurality of” means two or more, unless otherwise clearly and specifically defined.

[0029] like Figure 1-4 The figure shows a structure of a circulating fluidized bed boiler with a cooling chamber for burning mixed fuels, comprising: a steam drum 1, a furnace 2, a water-cooled air chamber 3, a superheating system, a return device 5, a downcomer 6, a top connecting pipe 7, an upper economizer 14, an air preheater, a lower economizer 16, a feed interface 19, and an ignition device 20, characterized in that:

[0030] A water-cooled air chamber 3 is provided at the lower part of the furnace 2, and a low-nitrogen combustion air hood is arranged on the water-cooled air chamber 3. Three layers of secondary air ducts 18 are arranged on the front and rear walls of the dense phase area of ​​the furnace 2 respectively, and a screen-type heating surface is arranged in the furnace to effectively increase the superheated steam temperature.

[0031] The front and rear walls of the furnace are equipped with three layers of secondary air ducts to improve the penetration of secondary air and ensure complete combustion. The front wall is equipped with a feed port 19, the height of which is greater than the zero pressure zone of the furnace.

[0032] Furnace 2 forms a natural circulation system with steam drum 1 through downcomers 6 and top connecting pipes 7. Flue gas is drawn from the upper rear wall of furnace 2 and enters steam-cooled separator 4. After separation in steam-cooled separator 4, large particles are fed back into furnace 2 via a return device 5 for continued combustion. Clean flue gas separated by steam-cooled separator 4 is drawn through the central tube and enters the U-shaped channel cooling chamber wall 8.

[0033] The superheating system includes a steam-cooled separator 4, a low-temperature superheater 10, a first-stage water spray desuperheater 11, a medium-temperature superheater 12, a second-stage water spray desuperheater 13 and a platen superheater 9.

[0034] The entire superheating system, consisting of a steam-cooled separator, low-temperature superheater, primary water-spray desuperheater, medium-temperature superheater, secondary water-spray desuperheater, and platen superheater, maintains the superheated steam temperature. The entire superheating system is contained within the enclosure wall, ensuring excellent sealing and minimal air leakage. The steam-cooled separator boasts high separation efficiency, ensuring sufficient circulating material within the boiler.

[0035] The flue gas chamber behind the cooling chamber is arranged from bottom to top with a low-temperature superheater 10 and a medium-temperature superheater 12. A first-stage water spray desuperheater 11 is located between the low-temperature superheater 10 and the medium-temperature superheater 12. The outlet pipe of the medium-temperature superheater 12 is connected to a second-stage water spray desuperheater 13. After the second stage of desuperheating, the steam enters the platen superheater 9 located within the furnace 2. From the platen superheater outlet header, the steam is introduced into the steam collection header through a connecting pipe. After passing through the medium-temperature superheater 12, the flue gas connects to the flue duct 27 behind the cooling chamber wall and enters the tail shaft flue. The platen superheater 9 is located within the furnace 2, effectively raising the superheated steam temperature.

[0036] The air preheater adopts a multi-stage arrangement, consisting of a high-temperature air preheater and a low-temperature air preheater. The high-temperature air preheater is arranged between the upper economizer and the lower economizer, which increases the temperature of the primary air. The hot air temperature can reach 230°C, which has a pre-drying effect on the chicken manure and biomass entering the furnace, thereby improving combustion efficiency.

[0037] It includes a high-temperature air preheater 15 and a low-temperature air preheater 17. The high-temperature air preheater 15 is arranged between the upper economizer 14 and the lower economizer 16. The tail shaft flue is arranged from top to bottom with the upper economizer 14, the high-temperature air preheater 15, the lower economizer 16, the low-temperature air preheater 17, and the air preheater ash hopper 24.

[0038] A U-shaped cooling chamber enclosure 8 is installed between the steam-cooled separator 4 and the upper economizer 14. This enclosure comprises a front enclosure 32, a rear enclosure 33, side enclosures 34, and a partition enclosure 35. This enclosure forms a natural circulation with the steam drum 1 through a downcomer 6 and a top connecting pipe 7. A spray system 29 is located at the top of the flue gas chamber in front of the U-shaped cooling chamber enclosure 8. This system regulates the temperature of the flue gas entering the low-temperature superheater, thereby reducing the wall temperature of the tubes. This prevents high-temperature flue gas corrosion and ash buildup on the tubes. A cooling chamber ash hopper 23 is located at the bottom.

[0039] The furnace is high, with a large cross-sectional area, sufficient heating area, low flow rate, and the combustion temperature is controlled not to be higher than 800℃. A U-shaped channel cooling chamber wall is set between the steam-cooled separator and the upper economizer. The U-shaped channel cooling chamber wall consists of a front wall, a rear wall, a side wall, and a partition wall. They are all membrane water-cooled wall structures, forming a U-shaped channel. The cooling chamber wall can quickly reduce the flue gas temperature from 800℃ to within 650℃, effectively reducing the flue gas temperature passing through the superheater, avoiding excessively high temperature of the superheater tube wall, and preventing high-temperature corrosion. At the same time, the insulated cooling chamber ash hopper set at the bottom of the U-shaped channel cooling chamber wall can collect a large amount of smoke and dust, greatly reducing the dust accumulation and corrosion of the superheater.

[0040] The medium-temperature superheater and the upper economizer are connected through a flue 27 behind the cooling chamber wall.

[0041] Telescopic steam sootblowers 21 are located in the low-temperature superheater 10 and medium-temperature superheater 12 regions, fixed rotary steam sootblowers 36 are located in the upper economizer 14 and lower economizer 16 regions, and shock wave sootblowers 22 are located in the high-temperature air preheater 15 and low-temperature air preheater 17 regions. The sootblowers effectively prevent soot accumulation on the convection heating areas of the boiler.

[0042] The front enclosing wall 32 , the rear enclosing wall 33 , the side enclosing wall 34 , and the partition enclosing wall 35 are all membrane-type water-cooled wall structures, which together form a U-shaped channel.

[0043] The low-temperature superheater 10, medium-temperature superheater 12, upper economizer 14, high-temperature air preheater 15, lower economizer 16, and low-temperature air preheater 17 are all arranged in series with a large spacing to effectively prevent ash blockage. The primary and secondary air duct boxes of the high-temperature air preheater 15 and low-temperature air preheater 17 are all made of enameled pipes. The duct boxes are arranged independently to prevent low-temperature corrosion and facilitate replacement.

[0044] Compressed air purge devices 28 are arranged on the risers of the return material device 5 and the cooling chamber ash hopper 23, respectively, which are conducive to the smooth falling of the return material. Compressed air purge devices are arranged on the risers of the cooling chamber ash hopper, which are conducive to the smooth falling of the cooling ash.

[0045] SNCR nozzles 30 are located at the inlet of the steam-cooled separator 4, injecting ammonia or urea solution. The flue gas temperature at the furnace outlet is approximately 800°C, removing 50-60% of NOx from the flue gas. A large-diameter adiabatic slag discharge port is located at the bottom of the furnace.

[0046] Refractory castables are applied to the top and outlet of the furnace 2, within the steam-cooled separator 4, at the front smoke chamber inlet and top, at the bottom bend, and at the rear smoke chamber outlet and top of the U-shaped channel cooling chamber wall 8. Refractory castables are also applied to the lower L-shaped bend of the platen superheater 9 and on the water-cooled membrane wall where the platen superheater 9 penetrates the wall. This enhances the wall's wear resistance and ensures safe and stable boiler operation.

[0047] The boiler's structural layout fully considers ash blockage prevention and corrosion prevention. The convection heating surfaces are arranged in series with large intercepts, and the high maintenance space facilitates shutdown maintenance and ash cleaning.

[0048] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment according to the essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A circulating fluidized bed boiler structure for burning mixed fuels with a cooling chamber, comprising: The steam drum (1), furnace (2), water-cooled air chamber (3), superheating system, return device (5), downcomer (6), top connecting pipe (7), upper economizer (14), air preheater, lower economizer (16), feed interface (19) and ignition device (20) are characterized by: A water-cooled air chamber (3) is provided at the lower part of the furnace (2), and a low-nitrogen combustion air cap is arranged on the water-cooled air chamber (3). Three layers of secondary air ducts (18) are arranged on the front and rear walls of the dense phase zone of the furnace (2), and a feeding interface (19) is arranged on the front wall, the height of which is greater than the zero-pressure zone of the furnace; The furnace (2) forms a natural circulation with the steam drum (1) through the downcomer (6) and the top connecting pipe (7); The superheating system includes a steam-cooled separator (4), a low-temperature superheater (10), a first-stage water spray desuperheater (11), a medium-temperature superheater (12), a second-stage water spray desuperheater (13) and a platen superheater (9); the low-temperature superheater (10) and the medium-temperature superheater (12) are arranged from bottom to top in the smoke chamber behind the cooling chamber, and a first-stage water spray desuperheater (11) is arranged between the low-temperature superheater (10) and the medium-temperature superheater (12); the outlet pipe of the medium-temperature superheater (12) is connected to the second-stage water spray desuperheater (13), and the platen superheater (9) is arranged in the furnace (2); The air preheater adopts a multi-stage arrangement, which includes a high-temperature air preheater (15) and a low-temperature air preheater (17). The high-temperature air preheater (15) is arranged between the upper economizer (14) and the lower economizer (16). The tail shaft flue is arranged from top to bottom with the upper economizer (14), the high-temperature air preheater (15), the lower economizer (16), the low-temperature air preheater (17), and the air preheater ash hopper (24). A U-shaped channel cooling chamber wall (8) is provided between the steam-cooled separator (4) and the upper economizer (14). The U-shaped channel cooling chamber wall (8) includes a front wall (32), a rear wall (33), a side wall (34), and a partition wall (35). The U-shaped channel cooling chamber wall (8) forms a natural circulation with the steam drum (1) through the downcomer (6) and the top connecting pipe (7); The medium-temperature superheater and the upper economizer are connected via a flue (27) behind the cooling chamber wall; Long telescopic steam soot blowers (21) are arranged in the low-temperature superheater (10) and medium-temperature superheater (12) regions, and fixed rotary steam soot blowers (36) are arranged in the upper economizer (14) and lower economizer (16) regions; shock wave soot blowers (22) are arranged in the high-temperature air preheater (15) and low-temperature air preheater (17) regions; The front wrapping wall (32), the rear wrapping wall (33), the side wrapping wall (34), and the partition wrapping wall (35) are all membrane-type water-cooled wall structures, which together form a U-shaped channel.

2. A circulating fluidized bed boiler structure for burning mixed fuels with a cooling chamber according to claim 1, characterized in that: The low-temperature superheater (10), the medium-temperature superheater (12), the upper economizer (14), the high-temperature air preheater (15), the lower economizer (16) and the low-temperature air preheater (17) are all arranged in series with a large intercept. The primary and secondary air duct boxes of the high-temperature air preheater (15) and the low-temperature air preheater (17) are all made of enameled pipe materials, and the pipe boxes are arranged independently.

3. The circulating fluidized bed boiler structure for burning mixed fuels with a cooling chamber according to claim 1, characterized in that: Compressed air blowing devices (28) are respectively arranged on the vertical pipes of the return device (5) and the cooling chamber ash hopper (23).

4. The circulating fluidized bed boiler structure for burning mixed fuels with a cooling chamber according to claim 1, characterized in that: An SNCR nozzle (30) is arranged at the inlet of the steam cooling separator (4), and a large-diameter adiabatic slag discharge port is arranged at the bottom of the furnace.

5. The circulating fluidized bed boiler structure for burning mixed fuels with a cooling chamber according to claim 1, characterized in that: Refractory castables are applied to the top and outlet of the furnace (2), the steam-cooled separator (4), the front smoke chamber inlet and top, the bottom bend, and the rear smoke chamber outlet and top of the U-shaped channel cooling chamber wall (8); and refractory castables are applied to the L-shaped bend at the lower part of the screen superheater (9) and on the water-cooled membrane wall at the wall through which the screen superheater (9) passes.

6. The circulating fluidized bed boiler structure for burning mixed fuels with a cooling chamber according to claim 1, characterized in that: A spray system (29) is arranged on the top of the smoke chamber in front of the U-shaped channel cooling chamber wall (8), and a cooling chamber ash hopper (23) is arranged on the bottom.

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