Tail flue structure of circulating fluidized bed boiler for purely burning furfural residues
By designing an N-shaped flue and staggered arrangement of low-temperature economizers in the tail flue of a circulating fluidized bed boiler, the problems of slagging, ash accumulation, and corrosion caused by furfural residue combustion were solved, thus improving the stability and safety of the boiler.
Patent Information
- Application Number
- CN202422642096.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-10-24
- Estimated Expiration
- 2034-10-31
AI Technical Summary
In existing technologies, the tail flue of circulating fluidized bed boilers that burn only furfural residue is prone to slagging, ash accumulation, and corrosion due to the characteristics of furfural residue, leading to boiler instability and reliability issues. In particular, condensation is prone to form low-temperature corrosion at the last stage air preheater.
An N-shaped flue structure is designed to concentrate the slag falling from the high-temperature zone to the lower part, preventing it from being carried to the low-temperature economizer and air preheater. Combined with a staggered arrangement of low-temperature economizers, corrosion-resistant materials and reasonable flue gas velocity are used to reduce flue gas temperature and prevent ash accumulation and corrosion.
This effectively avoids ash accumulation and wear in the low-temperature economizer and air preheater, improves the stability and reliability of the boiler, prevents low-temperature corrosion, and ensures the safe operation of the boiler.
Smart Images
Figure CN223470171U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a circulating fluidized bed boiler, especially to a tail flue structure of circulating fluidized bed boiler of pure furling residue burning. BACKGROUND
[0002] Furling residue is a kind of biomass substance, which is a kind of biomass waste produced by refining furling residue, and contains acid liquid, sulfur and chlorine components, and is rich in alkali metal, and has the characteristics of high moisture content and low calorific value, how to treat furling residue in an environmentally friendly manner is a difficult problem that the relevant enterprises and environmental protection departments urgently need to solve at present, at present, there are reports on the combustion treatment of furling residue by small capacity chain furnace, but this treatment method has the defect of limited furling residue treatment capacity, and cannot meet the market requirements, and due to the characteristics of furling residue, there is also the problem of slagging in the hearth, how to develop a circulating fluidized bed boiler suitable for pure furling residue burning through the circulating fluidized bed boiler technology of flow state reconstruction, and the furling residue treatment capacity covers 10-62 tons per hour (calculated at 45% moisture content), so as to realize the digestion of a large amount of furling residue, and produce steam from waste, and the steam pressure is 3.82-13.73 MPa, which has become a problem that needs to be solved on site.
[0003] The calorific value of furling residue is low (the calorific value is 1400-2200 kilocalories per kilogram), and the moisture content is as high as 40-60%, so a large amount of flue gas will be generated after furling residue is burned, the alkali metal content of furling residue is high, and a small amount of acid liquid, sulfur and chlorine are left, the high alkali metal content will lead to low ash melting point, and the heating surface in the tail flue is easy to slag, accumulate ash and be corroded, especially the moisture in the flue gas is more likely to form dew condensation at the position of the last stage air preheater, and then low temperature corrosion is formed, and even the ash is blocked together, in view of these characteristics, how to design and layout the tail flue has become a problem that needs to be solved on site. SUMMARY
[0004] The utility model provides a kind of circulating fluidized bed boiler tail flue structure of pure furling residue burning, solve how to design and layout tail flue, overcome the technical problem that pure furling residue burning flue gas makes the heating surface of flue easy to slag, accumulate ash and corrosion.
[0005] The utility model is solved above-mentioned technical problem by following technical scheme:
[0006] The tail flue structure of a circulating fluidized bed boiler of pure pyrolysis residue comprises a furnace, a cyclone separator and a return device; a first flue is connected to the central outlet cylinder of the cyclone separator, the lower end of the first flue is connected with a second flue through a connecting flue, the first flue, the connecting flue and the second flue are arranged in an N shape, a first flue bottom end ash discharge hopper is arranged at the lower end of the first flue, and a second flue bottom end ash discharge hopper is arranged at the lower end of the second flue; a high-temperature superheating screen and a medium-temperature superheating screen are arranged in the furnace, an evaporation tube bundle, a low-temperature superheater and a high-temperature economizer are arranged in the first flue, a low-temperature economizer and an air preheater are arranged in the second flue, and the smoke outlet at the lower end of the second flue is connected with a chimney through a dust remover and a desulfurization device and an induced draft fan in sequence.
[0007] The tube rows of the low-temperature superheater are arranged in line, and the tube row pitch is 100 mm; the tube rows of the evaporation tube bundle are arranged in line, and the tube row pitch is 200 mm; the tube rows of the high-temperature economizer are arranged in line; and the tube rows of the low-temperature economizer are arranged in staggered rows.
[0008] The average flow velocity of flue gas at the low-temperature superheater in the first flue is 9 m / s, the average flow velocity of flue gas at the low-temperature economizer in the second flue is 7 m / s, and the exhaust gas temperature of the smoke outlet at the lower end of the second flue is 140 DEG C.
[0009] The N-shaped flue is arranged, so that once the large slag block formed in the high-temperature zone falls, the slag block only falls in the lower part of the N-shaped flue and cannot be brought to the positions of the low-temperature economizer and the air preheater, so that the low-temperature economizer and the air preheater are relatively safe, the ash deposition, blockage and even abrasion caused by the slag block falling on the heating surface can be avoided, and the stability and reliability of the boiler are greatly improved; meanwhile, the design of the N-shaped flue makes it possible to design the economizer in a staggered structure, so that the structure is more compact and conditions are created for more flexible setting of SCR. BRIEF DESCRIPTION OF DRAWINGS
[0010] Figure 1 is a structural schematic view of the utility model. DETAILED DESCRIPTION
[0011] The utility model will be described in detail in combination with the drawings:
[0012] The application relates to a tail flue structure of a circulating fluidized bed boiler of pure fural residue, which comprises a furnace 1, a cyclone separator 2 and a returning device 3, a first flue 4 is connected to the central outlet cylinder of the cyclone separator 2, the lower end of the first flue 4 is connected with a second flue 5 through a connecting flue 6, the first flue 4, the connecting flue 6 and the second flue 5 are arranged in an N shape, a first flue bottom ash discharging hopper 7 is arranged at the lower end of the first flue 4, and a second flue bottom ash discharging hopper 8 is arranged at the lower end of the second flue 5; a high-temperature superheater and a medium-temperature superheater 16 are arranged in the furnace 1, the high-temperature heating surface is arranged in the furnace, the pipe material is TP347H which has better corrosion resistance, according to the characteristics of the fuel, the fly ash is easy to adhere to the heating surface pipe with a wall temperature of 500-600 DEG C to cause scale under corrosion, the medium temperature of the high-temperature superheater is 540 DEG C at most, and the wall temperature is above 550-580 DEG C, therefore, the high-temperature superheater is arranged in the furnace, a large amount of wall-attached backflow material is used to wash the heating surface, and the scale adhesion is avoided to cause corrosion, and the arrangement mode solves the corrosion problem of the high-temperature heating surface; an evaporation tube bundle 17, a low-temperature superheater 9 and a high-temperature economizer 10 are arranged in the first flue 4 respectively, a low-temperature economizer 11 and an air preheater 12 are arranged in the second flue 5 respectively, the smoke outlet at the lower end of the second flue 5 is sequentially connected with a dust remover and a desulfurization device 13, an induced draft fan 14 and a chimney 15; considering that the fural residue has the characteristics of biomass, slagging is inevitable in the high-temperature area, in order to avoid the slag formed in the high-temperature area from falling to the lower heating surface, causing the lower heating surface to produce scale, blockage and even wear and tear and other problems, a N-shaped flue is specially designed, the flue gas passes through the N-shaped flue and then enters the second flue 5 in a vertical shaft type, and the heating surface in the rear part is protected; the low-temperature economizer and the air preheater are arranged separately, which is different from the conventional furnace type arranged in the first flue 4 in a vertical shaft type, and the low-temperature economizer and the air preheater are arranged in the second flue 5.
[0013] The tube rows of the low-temperature superheater 9 are arranged in series, the tube row pitch is 100 mm; the tube rows of the evaporation tube bundle 17 are arranged in series, the tube row pitch is 200 mm; the tube rows of the high-temperature economizer 10 are arranged in series; the tube rows of the low-temperature economizer 11 are arranged in staggered rows; the evaporation tube bundle 17 of the water cooling system arranged in the tail flue reduces the flue gas temperature from 740-780 DEG C to below 690 DEG C, the steam temperature at the low-temperature superheater outlet is 400 DEG C, and the wall temperature is below 450 DEG C, so that the tail heating surface corrosion is controlled; the wear-resistant protective tile made of 06Cr23Ni13 is arranged on the evaporation tube bundle 17, and plays a role of wear resistance and corrosion resistance.
[0014] The average flow rate of flue gas at the low-temperature superheater in the first flue 4 is 9 meters per second, and the average flow rate of flue gas at the low-temperature economizer in the second flue 5 is 7 meters per second; the exhaust temperature of the exhaust outlet at the lower end of the second flue 5 is 140 DEG C; the exhaust temperature is designed to be 140 DEG C, and combined with the flue gas purification system, the exhaust temperature can be appropriately increased to avoid the water in the flue gas from being condensed at the position of the last-stage air preheater, thereby forming low-temperature corrosion, even forming blockage together with the ash, the air preheater is arranged in a horizontal in-line manner, the tube pitch is appropriately increased, and corrosion-resistant CORTEN steel is used, so that the ash corrosion is effectively avoided, and the operation stability of the boiler is improved.
Claims
1. A circulating fluidized bed boiler back pass structure of pure pyrolysis furfural residue, comprising a furnace (1), a cyclone separator (2) and a return device (3); characterized in that, The first flue (4) is connected to the center outlet cylinder of the cyclone separator (2), the lower end of the first flue (4) is connected with the second flue (5) through the connecting flue (6), the first flue (4), the connecting flue (6) and the second flue (5) are arranged in N shape, the first flue bottom ash bucket (7) is arranged at the lower end of the first flue (4), the second flue bottom ash bucket (8) is arranged at the lower end of the second flue (5); the high-temperature superheating screen and the medium-temperature superheating screen (16) are arranged in the furnace (1), the evaporation tube bundle (17), the low-temperature superheater (9) and the high-temperature economizer (10) are respectively arranged in the first flue (4), the low-temperature economizer (11) and the air preheater (12) are respectively arranged in the second flue (5), the smoke outlet at the lower end of the second flue (5) is communicated with the chimney (15) through the dust remover, the desulfurization equipment (13) and the induced draft fan (14) in sequence.
2. A circulating fluidized bed boiler back pass structure of pure fumus huffkae according to claim 1, characterized in that, The tube rows of the low-temperature superheater (9) are arranged in sequence, the tube row pitch is 100 mm; the tube rows of the evaporation tube bundle (17) are arranged in sequence, the tube row pitch is 200 mm; the tube rows of the high-temperature economizer (10) are arranged in sequence; the tube rows of the low-temperature economizer (11) are arranged in staggered manner.
3. A circulating fluidized bed boiler back pass structure of pure fumus huffkae according to claim 1 or 2, characterized in that, The average flow velocity of the flue gas at the low-temperature superheater in the first flue (4) is 9 m / s, the average flow velocity of the flue gas at the low-temperature economizer in the second flue (5) is 7 m / s; the exhaust temperature of the smoke outlet at the lower end of the second flue (5) is 140 DEG C.