BFB / CFB boiler flow state and combustion reconstruction energy-saving synergistic low-emission large-scale structure and method

Abstract

The invention discloses a BFB / CFB boiler flow state and combustion reconstruction energy-saving synergistic low-emission large-scale structure and method. According to the BFB boiler system, an ash hopper for collecting fly ash at a flue gas outlet of a hearth is removed, and a novel low-resistance efficient multifunctional inertia gravity gas-solid separation and boiling combustion carbon burnout and radiation and convective heat transfer integrated auxiliary combustion chamber is formed; the three problems of high initial smoke dust emission, high fly ash carbon content and buried pipe abrasion are solved, and the single-unit capacity of the BFB boiler is increased from 50 MW to 300 MW. According to the CFB boiler system, a cyclone separator, a material returning circulating system and secondary air are removed; the novel low-resistance efficient gas-solid separation and combustion integrated multifunctional auxiliary combustion chamber is shared with the BFB boiler; the pain point of high power consumption of a drum fan and an induced draft fan is fundamentally solved, and the pain point of high energy consumption of raw materials is also solved; 30%-40% of power consumption of an air blower can be saved, 30% of power consumption of an induced draft fan can be saved, and 50% of fire-resistant thermal insulation materials and a steel frame can be saved; and particularly, the method for realizing the large-scale boiler can comprehensively surpass a pulverized coal furnace.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fluidized bed clean combustion technology, and relates to a BFB / CFB boiler popular in the global market, which not only ensures that the new structure and method of the CFB boiler of the present application achieve ultra-large energy saving and efficiency and ultra-low emission, but also solves the bottleneck of realizing ultra-large CFB boilers. It relates to a 2MW-300MW BFB boiler for large, medium and small biomass power generation, waste incineration power generation, cogeneration, clean coal industrial boilers and heating boilers. In particular, it relates to the development potential of >300MW-1400MW CFB ultra-large power station boilers. It relates to the upgrading and replacement of various large, medium and small traditional BFB boilers and CFB boilers in use, as well as the energy saving and emission reduction modification and replacement of pulverized coal boilers and grate chain boilers. BACKGROUND

[0002] Although the traditional BFB / CFB boiler has irreplaceable advantages such as wide fuel adaptability, high combustion efficiency, low-temperature combustion to reduce NO x emission and in-furnace desulfurization, it also has a series of inherent technical bottlenecks and pain points, which bring challenges to system design, operation economy and reliability.

[0003] The current BFB / CFB boiler technology has the following industry pain points:

[0004] BFB (bubbling fluidized bed) boiler: generally has low combustion efficiency, high carbon content in fly ash, serious wear of buried pipe in dense phase zone, and limited large-scale development;

[0005] CFB cyclone separator circulating fluidized bed boiler: complex system structure, high initial investment, large consumption of refractory materials and steel frame, high operation energy consumption (large proportion of fan power consumption), high maintenance cost due to equipment wear, and low large-scale capacity compared with pulverized coal boilers.

[0006] There is still room for optimization in existing related patent technologies:

[0007] Although the patent application number 202111173538.9 (under examination) discloses a "two-bed three-chamber water and steam cold ceiling four / six-return flue small fluidized bed BFB boiler", the combustion system of the main combustion chamber and the auxiliary combustion chamber has certain advantages, but there are problems such as unclear theoretical logic, poor six-return flue process structure, and unclear division of functions between the main combustion chamber "high-temperature cracking" and the auxiliary combustion chamber "carbon burnout + efficient radiation convection heat transfer". Moreover, it lacks a method for realizing large-scale development.

[0008] Although the authorized patent number ZL201480002881.9 (CFB boiler) has reduced flow resistance (saved induced fan power consumption), reduced the amount of wear-resistant materials and steel frame, and reduced the original smoke dust concentration by eliminating the cyclone separator through the "multifunctional inertial gravity gas-solid separator", but the technology still has iteration space;

[0009] The authorized patent number ZL202210081387.2 (CFB boiler) optimizes flow velocity and flow resistance by "furnace upper taper + two return down flue taper", and realizes CFB boiler technology iteration by "seven return flue full mode water wall integrated structure", but it does not solve the core problem of large primary air resistance and high blower power consumption.

[0010] The present application aims to fundamentally solve the above-mentioned problems of BFB / CFB boiler efficiency, energy consumption, wear and tear, and large-scale problems by structural innovation and flow state, combustion reconstruction. SUMMARY

[0011] 1. Invention purpose and core technology direction

[0012] The present application aims to solve the problems of high raw material energy consumption, low comprehensive energy efficiency, high initial emission concentration of smoke dust, high failure rate, and high maintenance and repair cost of existing BFB / CFB boiler. Through flow state reconstruction, combustion reconstruction, and low resistance high efficiency inertial gravity gas-solid separation technology, the following goals are achieved: significant energy saving and efficiency increasing, ultra-low emission, large-scale capacity surpassing pulverized coal furnace, while reducing the crushing energy consumption by 83%, breaking the monopoly position of pulverized coal furnace in the field of ultra-large units.

[0013] 2. BFB / CFB boiler combustion system structure

[0014] (1) New type of combustion system of BFB boiler

[0015] (a) Overall structure: composed of one main combustion chamber furnace, one two return down tapered flue, and one three return flue of auxiliary combustion chamber.

[0016] (b) Flow state reconstruction: the upper half of the rear mode water-cooled wall of the main combustion chamber furnace is bent and inclined forward from the appropriate position and tapered to the furnace outlet to gradually increase the dilute phase zone smoke velocity, realize heat gathering and strengthen combustion, and expand the two return flue inlet section to reduce the flow resistance.

[0017] (c) Combustion reconstruction: cancel the buried pipe and the fly ash collection hopper at the furnace flue gas outlet, design the space from the rear wall of the "furnace mode water-cooled wall to the front wall of the vertical shaft mode water-cooled wall" as a two-pass downward tapered flue and a three-pass flue of the auxiliary combustion chamber; wherein the front wall of the two-pass flue and the rear wall of the main combustion chamber share the furnace, and the rear wall shares the three-pass flue; the upper end to the bottom of the two / three-pass flues at 8 / 10 height of the air distribution plate are the outlet of the two-pass flue and the inlet of the three-pass flue, respectively; the auxiliary combustion chamber is composed of "the outlet of the two-pass flue to the air distribution plate at 2 / 10 height (defined as H)" and "the whole three-pass flue of the auxiliary combustion chamber".

[0018] (2) New combustion system of CFB boiler

[0019] (a) Overall structure: composed of 1 pair of trousers furnace (matching 2 main combustion chambers), 1 two-pass downward tapered flue in front and back, and 1 three-pass flue of the auxiliary combustion chamber in front and back.

[0020] (b) Flow state reconstruction: the flow velocity in the dense phase zone is lower than the low ratio flow velocity; the upper half of the front and rear mode water-cooled walls of the pair of trousers furnace are inwardly bent, tilted and tapered to the furnace outlet from the appropriate position; the flue gas flow velocity enters the two-pass downward tapered flue at about 5 m / s, and is increased to 7-9 m / s at the outlet, and then enters the three-pass flue and maintains a low flow velocity of 2-3 m / s.

[0021] (c) Combustion reconstruction:

[0022] ① Cancel the cyclone separator at the upper part of the front end of the pair of trousers furnace and the material circulating return system at the lower part, and design the corresponding space as a two-pass downward tapered flue and a three-pass flue; the front wall of the two-pass flue and the rear wall of the three-pass flue share the furnace, and the rear wall shares the front wall of the pair of trousers furnace; the auxiliary combustion chamber is composed in the same way as the BFB boiler (two-pass outlet to air distribution plate at 2 / 10H height + whole three-pass flue).

[0023] ② The space from the "cyclone separator to the front mode water-cooled wall transverse wall" at the rear end of the pair of trousers furnace is designed as a two-pass downward tapered flue and a three-pass flue; the front wall of the two-pass flue and the rear wall of the pair of trousers furnace share the furnace, and the rear wall shares the front wall of the three-pass flue; the rear wall of the three-pass flue shares the front wall of the vertical shaft flue; the auxiliary combustion chamber is composed in the same way as above.

[0024] 3. Shared low-resistance high-efficiency inertial gravity gas-solid separation technology

[0025] (1) Technical principle

[0026] Without a dedicated separation device, through precise design of the two / three-pass flue structure after the dust-containing flue gas leaves the furnace, the functions of inertial separation, gravity sedimentation, radiation heat transfer and convection heat transfer are integrated by utilizing the two 180° turns of the flue gas, the sharp change (acceleration and sudden drop) of the flow velocity and the layout of the process.

[0027] (2) Key structure and working process

[0028] ① Furnace outlet and secondary combustion chamber guide design: A guide function water-cooled wall is arranged behind the furnace outlet to guide the dust-containing flue gas to the air distribution plate at the bottom of the secondary combustion chamber, so that the combustible solid particles suspended in the upper part of the furnace can be directly transported to the air distribution plate, realizing the forced backflow and reburning of the material.

[0029] ② Two-return flue high-speed concentration process: The gas-solid two-phase flow flows out from the furnace outlet at about 5 m / s, turns 180 degrees into the two-return downward tapered flue, and the flue gas flow rate increases with the flue tapering; under the combined action of turning inertia, air flow drag force, vertical downward air flow blowing force and its own gravity, the falling speed of solid particles exceeds the flue gas flow rate, and finally falls rapidly from the two-return outlet into the air distribution plate.

[0030] ③ Three-return inlet separation design: The height (H) of the lower end of the guide water-cooled wall and the air distribution plate and the three-return inlet structure form a 90° turning and cross-section sudden expansion channel, realizing double effects: one is that the 7-9 m / s high-speed airflow penetrates the material layer of the secondary combustion chamber, disturbs and loosens the material and supplements oxygen; the other is that the cross-section sudden expansion causes the flue gas flow rate to drop to 2-3 m / s, and the particulate matter is all settled on the air distribution plate under the action of gravity, completing the gas-solid separation.

[0031] ④ Three-return flue burnout and final separation: A small amount of fine particles enter the large cross-section three-return flue (2-3 m / s low-speed upward) along with the airflow, and the carbon particles are burned out in sufficient residence time; the high-temperature superheater in the flue has the functions of convective heat transfer and inertial separation, further capturing particles.

[0032] ⑤ Emission effect: After multi-stage separation, the initial emission concentration of flue dust is reduced by 8-10 times compared with that of traditional cyclone separator CFB boilers.

[0033] 4. Energy-saving and efficiency-increasing structure and method (taking a 600 MW CFB boiler as an example)

[0034] (1) Energy-saving structure and theoretical basis

[0035] ① Cancel the cyclone separator and the return system, save 15%-25% of refractory insulation materials and steel frame of the whole machine.

[0036] ② Transform the space from the above-mentioned canceled components to the front wall of the shaft into a two-return downward tapered flue and a three-return flue, reduce the 50m high furnace by 40%, and save about 40% of refractory insulation materials and steel frame.

[0037] ③ Integrated structure reduces 2 horizontal walls and 1 longitudinal flue, which can save about 30% of refractory insulation materials and steel frame.

[0038] (4) Energy saving: The theoretical energy saving ratio is (15% + 40% + 30%) - the material consumption of the newly added two guiding water-cooled walls (about 30%), and the final energy saving ratio is about 55%.

[0039] (2) Synergistic structure and theoretical basis

[0040] (1) Flow resistance reduction: The flue gas velocity of the second return pass is 5-9 m / s, the flue gas velocity of the auxiliary combustion chamber and the third return pass is 2-3 m / s, the flow resistance is reduced by more than 30% compared with the cyclone separator (the optimal flow velocity for gas-solid separation efficiency is 30 m), and the power consumption of the induced draft fan is reduced by 30%.

[0041] (2) Blast power saving: The furnace height is reduced by 40%, the fluidization height is reduced by 40%, the return material system is cancelled to save the return material power, the auxiliary combustion chamber shares 30% of the blast power of the main combustion chamber, and the secondary air of the main combustion chamber is used for the auxiliary combustion chamber, which reduces the primary air power by about 40% and saves the power consumption of the blast fan by about 30%-40%.

[0042] (3) Maintenance cost reduction: The low-resistance and high-efficiency gas-solid separation technology eliminates the high failure rate problem of the cyclone separator, and saves 70% of the maintenance and repair costs.

[0043] (4) Thermal efficiency improvement: First, the ultra-low smoke emission reduces the dust adhesion on the heating surface, reducing the thermal resistance and flow resistance; second, the heat transfer performance of the double-sided mode water-cooled wall with 5 transverse walls and 1 longitudinal flue is better than that of the single-sided heating cyclone separator CFB boiler with all mode water-cooled wall; third, the auxiliary combustion chamber (height 30 m, flue gas velocity 2-3 m / s) prolongs the combustion residence time, and the carbon content in fly ash is less than 1%; fourth, the seven-return pass flue of the integrated structure of the full mode water-cooled wall prolongs the flue gas process and reduces the exhaust gas temperature; the thermal efficiency is improved by 1%-2%.

[0044] (5) Life extension: The integrated structure of the full mode water-cooled wall can extend the service life of the boiler by 3-5 years. Theoretical basis for synergistic effect: ① Induced draft fan power consumption reduced by 30% + ② Blast fan power consumption saved by about 30%-40% + ③ Maintenance and repair costs saved by 70% + ④ Thermal efficiency improved by 1%-2% + Boiler service life extended by 3-5 years.

[0045] 5. Ultra-low emission implementation method

[0046] (1) Dust control: Low-resistance and high-efficiency inertial gravity gas-solid separation technology is adopted, and the initial emission concentration of BFB / CFB boiler dust is controlled at 1200-1500 mg / m 3 , which is 10 times lower than the national standard of 15000 mg / m 3 .

[0047] (2) Nitrogen oxide (NOx) control: Ultra-low NOx emission is achieved through high-temperature and low-oxygen combustion technology.

[0048] ③Carbon dioxide (CO2) control: Coupling oxy-combustion technology to produce high-concentration CO2 flue gas, combined with carbon capture, utilization and storage (CCUS) technology, to achieve near-zero CO2 emissions.

[0049] 6. Large-scale implementation method and BFB / CFB mode characteristics

[0050] (1) Large-scale core means: Fuel particle size matching

[0051] By fine fuel preparation (reducing particle size), different capacity units are adapted, with specific parameters as follows:

[0052] (a) BFB boiler: 2-100MW unit adapted fuel particle size 6-25mm; >100-300MW unit adapted fuel particle size 0-10mm.

[0053] (b) CFB boiler: 400-600MW unit adapted fuel particle size 0-6mm; >600-1000MW unit adapted fuel particle size 0-4mm; >1000-1400MW unit adapted fuel particle size 0-2mm.

[0054] (2) Large-scale technology advantages (double bed structure + 2mm fuel particle size)

[0055] ① Reduce fuel crushing energy consumption: Fuel crushing power consumption from >48kWh / t to <8kWh / t.

[0056] ② Break through capacity limit: Single machine capacity breaks through 1400MW, 7.7% higher than the limit capacity of pulverized coal furnace.

[0057] ③ Original environmental protection advantage: Original realization of NOx≤80mg / Nm 3 (pulverized coal furnace needs SCR post-treatment).

[0058] (3) Scientific statement

[0059] The 0.1mm fuel particle size requirement of pulverized coal furnace is a rigid constraint of the flame propagation speed of the burner. This technology breaks through this limit through fluidized combustion mechanism, and still achieves higher combustion efficiency when the fuel particle size is 2mm - boiler efficiency ≥93.5%, and ultra-supercritical pulverized coal furnace efficiency ≤92.8%.

[0060] (4) BFB and CFB mode characteristics

[0061] ① Core connotation: BFB and CFB share the core principle of fluidized combustion, with technical fusion, and can realize continuous switching and mutual conversion of operation modes by adjusting fuel particle size and operation parameters (such as wind speed).

[0062] ②Mode switching: BFB boiler can be switched to CFB mode by reducing fuel particle size and increasing wind speed; CFB boiler can present BFB operation characteristics by burning coarser fuel and reducing wind speed.

[0063] ③Commonality of large-scale: both of them rely on fine fuel preparation (reducing particle size) to achieve efficient circulating fluidization (CFB mode).

[0064] 7. The BFB / CFB fluidized bed boiler system, characterized in that the system is a dual-inertial fluidized bed inertial gravity separator (DIFB-IGS) system, comprising:

[0065] The main combustion chamber constitutes the core part of the switchable fluidized dual-inertial fluidized bed (DIFB), which realizes dynamic switching of BFB (bubbling fluidized bed) and CFB (circulating fluidized bed) operation modes by adjusting the water-cooled wall structure parameters, operating wind speed and bed pressure;

[0066] The inertial gravity separator (IGS) is composed of a two-return flue and a three-return flue, which realizes efficient gas-solid separation through two changes of smoke flow direction, one gas-solid two-phase downward co-flow and flow rate mutation (two-return outlet smoke speed 7-9 m / s, three-return flue smoke speed 2-3 m / s);

[0067] The secondary combustion chamber receives the coarse particulate material separated by the IGS, and realizes in-situ fluidized combustion through the air distribution plate, so that the unburned particles complete suspended combustion in the three-return flue of the secondary combustion chamber, thereby reducing the carbon content of fly ash; the lower end of the two-return flue and the three-return flue is connected to the air distribution plate of the secondary combustion chamber, and the smoke speed is 7-9 m to meet the 90-degree turning of the flue gas into the three-return flue, so as to forcibly disturb, loosen and mix the gas-solid two-phase and the material of the air distribution plate and supplement oxygen, while maximizing the residence time of combustible material in the secondary combustion chamber (≥10 seconds).

[0068] 8. The DIFB-IGS system, characterized in that the three-return flue of the secondary combustion chamber of the inertial gravity separator (IGS) adopts an expanded capacity design, and the cross-sectional area is more than 3 times the cross-sectional area of the two-return flue outlet, so that the flue gas flow rate in the three-return flue is reduced to 2-3 m / s, realizing:

[0069] (a) Enhancing the effect of particle gravity sedimentation and improving the separation efficiency of fine particles;

[0070] (b) Extending the flue gas residence time to ≥10 seconds to ensure complete combustion of fly ash residual carbon;

[0071] (c) Reducing the flow resistance of the system, which forms a technical echo with "reducing the flow resistance by more than 30%" in claim 4.

[0072] 9. The DIFB-IGS system, characterized in that the main combustion chamber, the auxiliary combustion chamber and the inertial gravity separator (IGS) are integrated into one structure, comprising:

[0073] The shared main combustion chamber rear wall, the two-pass flue front wall, the two-pass flue rear wall, the three-pass flue front wall, the three-pass flue rear wall and the shaft flue front wall share a wall;

[0074] The five-pass mode water-cooled wall transverse wall adopts a double-sided heating design to achieve efficient heat conduction;

[0075] The shared air distribution system and flue process reduce the amount of refractory material by more than 30% and reduce manufacturing costs;

[0076] The optimized heat conduction path improves the thermal efficiency of the boiler by 1-2 percentage points, while simplifying the installation and maintenance process.

[0077] 10. The following is a detailed analysis of the Chinese meaning and technical correspondence of each letter in the DIFB-IGS system: DIFB-IGS full name disintegration

[0078] 1. DIFB part

[0079]

[0080] 2. IGS part

[0081]

[0082]

[0083] Complete Chinese technical expression

[0084] DIFB-IGS boiler (double inertial fluidized bed-inertial gravity separator boiler)

[0085] Chinese definition:

[0086] "A new type of boiler system that realizes gas-solid separation through an inertial gravity separator (IGS) and uses a double fluidized bed (DIFB) for collaborative combustion.

[0087] Its main combustion chamber can switch between bubbling and turbulent flow states, and the separated coarse particles are fluidized and burned in the auxiliary combustion chamber, eliminating the need for external return material circulation

[0088] Technical highlights and letter correspondence

[0089] (1) Double bed (D) → solves the problem of low burnout rate of traditional single bed;

[0090] (2) Inertia (I) → separation process without rotating parts, maintenance cost is extremely low;

[0091] (3) Gravity (G) → Natural sedimentation energy consumption is significantly lower than the centrifugal force of cyclone separation;

[0092] (4) Separator (S) → Integrated design reduces system complexity.

[0093] Advantages of the present application:

[0094] 1. Technical effect positioning

[0095] The present application reconstructs the flow state and combustion of BFB / CFB boiler. In the application scenario of ≥600MW CFB boiler, compared with traditional technology (global mainstream cyclone separator CFB boiler, pulverized coal furnace), the following breakthrough effects are presented (data based on natural attribute bottom-up logic theory and engineering prototype test):

[0096] 2. Performance comparison with traditional cyclone separator CFB boiler:

[0097] (1) Material and structure cost is greatly reduced: cancel the cyclone separator, return material system and other traditional components, and optimize the flue structure, greatly reduce the height of the furnace body and the integrated structure, the consumption of wear-resistant and refractory insulation materials is reduced by ≥50% (by weight), the amount of steel frame is reduced by ≥50% (by weight), and the cost of raw materials and equipment manufacturing and installation is significantly reduced.

[0098] (2) Energy consumption of air supply system is reduced: the fluidization height of the furnace is reduced by 40% through flow state combustion reconstruction, the material circulation system is cancelled and the air supply load of the main combustion chamber is shared by the auxiliary combustion chamber (boiling combustion reduces kinetic energy), combined with the optimization of the secondary air system, the power consumption of the air blower is reduced by 30%-40% (based on the same output working condition comparison).

[0099] (3) Energy consumption of induced draft system is reduced: the low resistance design of two-return down tapered flue and three-return flue (flue gas velocity 5-9 m / s and 2-3 m / s) makes the system flow resistance lower than the best separation flow velocity 30 m / s of traditional cyclone separator by more than 30%, and the power consumption of the induced draft fan is reduced by 30%.

[0100] (4) Gas-solid separation efficiency is improved: relying on low-resistance high-efficiency inertial gravity gas-solid separation technology, through two 180° flue gas turns, flow velocity sudden drop (7-9 m / s to 2-3 m / s) and superheater auxiliary separation, the actual gas-solid separation efficiency is more than 99.8%, close to complete separation.

[0101] (5) Combustion efficiency is optimized: the auxiliary combustion chamber (height 30 m, flue gas velocity 2-3 m / s) prolongs the residence time of fuel, and the forced backflow of material realizes secondary combustion, which is expected to realize fly ash carbon content <0.5%.

[0102] (6) Boiler thermal efficiency is significantly improved: combined with low resistance flow field design (reducing heat loss), multiple double-sided mode water wall (strengthening heat transfer), low fly ash carbon content (improving combustion completeness), seven return flue gas process is super long, and the boiler thermal efficiency is expected to reach 93%-97% (under rated load), which is 2-4 percentage points higher than that of traditional CFB boiler.

[0103] (7) Operation and maintenance cost is greatly reduced: the hidden troubles such as wear and blockage of traditional cyclone separator are eliminated, and there are no vulnerable parts of the return system, the actual maintenance and repair frequency is reduced by more than 70%, and the maintenance and repair cost is saved by 60%-80% (compared with annual operation and maintenance cost).

[0104] 3. Compared with the technical breakthrough of pulverized coal furnace (based on double-bed collaborative architecture + 2mm fuel particles)

[0105] (1) Surpassing the large-scale capacity: through fine fuel preparation (2mm fuel particles, crushing power consumption <8kWh / t) and double-bed collaborative fluidization design (main combustion chamber + auxiliary combustion chamber), the single machine capacity breaks through 1400MW, which is 7.7% higher than the limit capacity of pulverized coal furnace (about 1300MW), breaking the monopoly of pulverized coal furnace in the field of super large units.

[0106] This technology realizes three endings with double-bed architecture + 2mm fuel particles:

[0107] ① Ending the high energy consumption of pulverized coal furnace: the crushing power consumption is reduced from >48kWh / t to <8kWh / t

[0108] ② Ending the capacity advantage of pulverized coal furnace: the single machine capacity breaks through 1400MW (7.7% higher than the limit of pulverized coal furnace)

[0109] ③ Ending the environmental protection disadvantage of pulverized coal furnace: achieving NOx≤80mg / Nm 3 (pulverized coal furnace needs SCR post-treatment)

[0110] (2) Energy consumption advantage is obvious: the fuel crushing power consumption is reduced from >48kWh / t of pulverized coal furnace to <8kWh / t, the energy consumption is reduced by 83%, and the boiler thermal efficiency (≥93.5%) is higher than that of ultra-supercritical pulverized coal furnace (≤92.8%).

[0111] (3) Environmental protection performance leads: achieving NOx≤80mg / Nm 3 (no need for SCR post-treatment), while pulverized coal furnace needs to rely on SCR system to meet the standard, reducing environmental protection equipment investment and operation and maintenance cost.

[0112] 4. Environmental protection value extension (related to flow state and combustion reconstruction technology)

[0113] The flow state and combustion reconstruction technology of the present application optimizes the fuel combustion process (reduces the generation of NOx) through high-temperature low-oxygen combustion, and combines with oxygen-rich combustion design to make the CO2 concentration in the flue gas increase to more than 80% (create conditions for low-cost carbon capture); On this basis, the "combustion optimization-carbon capture-sequestration utilization (CCUS)" integrated technology system can realize the near-zero emission of CO2 in coal-fired power plants, and promote the clean transformation of the coal-fired power industry. BRIEF DESCRIPTION OF DRAWINGS

[0114] The drawings accompanying the specification of this application serve to provide further understanding of the present application, the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application.

[0115] In the drawings: Figure 1 is a BFB bubbling fluidized bed boiler scheme front view of the present application, one main combustion (furnace) matches one main air chamber, one two-return down tapered flue; one auxiliary combustion chamber three-return up flue matches one auxiliary air chamber;

[0116] Figure 2 is a CFB boiler scheme front view of the present application, one pair of trousers furnace matches two main combustion chambers and two main air chambers; the front and back of the pair of trousers furnace match two two-return down tapered flues and two auxiliary combustion chamber three-return flues and two auxiliary air chambers;

[0117] 1 - main air chamber, 2 - main air distribution panel, 3 - secondary air chamber, 4 - secondary air distribution panel, 5 - front wall of main combustion chamber, 6 - rear wall of main combustion chamber, 7 - three-pass flue of secondary combustion chamber, 8 - outlet of two-pass downwardly tapering flue, 9 - front upwardly tapering section of rear wall of main combustion chamber, 10 - water-cooled wall of front wall of main combustion chamber, 11 - two-pass downwardly tapering flue, 12 - outlet of main combustion chamber, 13 - superheater, 14 - three-pass flue outlet, 15 - shaft flue, 16 - three-pass flue of secondary combustion chamber, 17 - front wall membrane water-cooled wall of shaft, 18 - three-pass flue inlet, 19 - rear wall membrane water-cooled wall of shaft, 20 - main combustion chamber, 21 - outlet of shaft flue, 22 - secondary air chamber, 23 - air distribution panel of secondary air chamber, 24 - main air chamber, 25 - air distribution panel of main air chamber, 26 - main air chamber, 27 - air distribution panel of main air chamber, 28 - secondary air chamber, 29 - air distribution panel of secondary air chamber, 30 - front secondary combustion chamber of main combustion chamber, 31 - front wall pattern water-cooled wall of main combustion chamber, 32 - three-pass flue inlet of front wall of main combustion chamber, 33 - outlet of two-pass downwardly tapering flue of front wall of main combustion chamber, 34 - water-cooled wall of front wall of main combustion chamber, 35 - trousers combustion chamber, 36 - rearwardly tapering section of front wall of trousers combustion chamber, 37 - two-pass downwardly tapering flue of front wall of trousers combustion chamber, 38 - three-pass upwardly flue outlet of front wall of trousers combustion chamber, 39 - superheater, 40 - lower steam water-cooled wall of longitudinal flue, 41 - upper steam water-cooled wall of longitudinal flue, 42 - longitudinal steam water-cooled flue, 43 - superheater, 44 - flue gas inlet of shaft flue, 45 - three-pass flue outlet of rear wall of trousers combustion chamber, 46 - water-cooled wall of rear wall of trousers combustion chamber, 47 - shaft flue, 48 - outlet of two-pass downwardly tapering flue of rear wall of trousers combustion chamber, 49 - three-pass upwardly flue inlet of rear wall of trousers combustion chamber, 50 - rear wall pattern water-cooled wall of trousers combustion chamber, 51 - rear secondary combustion chamber of trousers combustion chamber, 52 - outlet of shaft flue, 53 - two-pass downwardly tapering flue of rear wall of main combustion chamber, 54 - rearwardly tapering section of rear wall pattern water-cooled wall of trousers combustion chamber, 55 - side symmetry pattern water-cooled wall, 56 - side symmetry pattern water-cooled wall, 57 - front transverse wall of whole machine, 58 - steam-cooled ceiling, 59 - front wall of shaft flue, 60 - flue gas outlet of front wall of main combustion chamber, 61 - flue gas outlet of rear wall of main combustion chamber, 62 - connecting pipe. DETAILED DESCRIPTION

[0118] The technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work belong to the protection scope of the present application.

[0119] Embodiment 1: please refer to the accompanying Figure 1In this embodiment, the BFB boiler has one main combustion chamber (furnace) matched with one main air chamber and one auxiliary combustion chamber three-pass flue matched with one auxiliary air chamber. The features include: main combustion chamber (furnace) 20, two-pass downwardly tapered flue 11, auxiliary combustion chamber three-pass flue 7, main air chamber 1, auxiliary air chamber 3. The main combustion chamber of the BFB boiler has the following features: the lower end of the main combustion chamber is the air distribution plate 2, the upper end is the water vapor cooling roof 58, the front wall is the furnace front wall 5, and the rear wall is the furnace rear wall 6.

[0120] The lower end of the auxiliary combustion chamber is the air distribution plate 4, the upper end is the two-pass downwardly tapered flue outlet 8 and the three-pass flue upper end to the water vapor cooling roof 58, the front wall is the two-pass downwardly tapered flue rear wall, the rear wall is the shaft front wall 17, and the two side walls are the side-symmetrical mode water-cooled wall 55.

[0121] Embodiment 2: Please refer to the attached Figure 2 In this embodiment, the BFB boiler has one main combustion chamber (furnace) matched with one main air chamber and one auxiliary combustion chamber three-pass flue matched with one auxiliary air chamber. The features include: main combustion chamber (furnace) 20, two-pass downwardly tapered flue 11, auxiliary combustion chamber three-pass flue 7, main air chamber 1, auxiliary air chamber 3. The main combustion chamber of the BFB boiler has the following features: the lower end of the main combustion chamber is the air distribution plate 2, the upper end is the water vapor cooling roof 58, the front wall is the furnace front wall 5, and the rear wall is the furnace rear wall 6.

[0122] The lower end of the auxiliary combustion chamber is the air distribution plate 4, the upper end is the two-pass downwardly tapered flue outlet 8 and the three-pass flue upper end to the water vapor cooling roof 58, the front wall is the two-pass downwardly tapered flue rear wall, the rear wall is the shaft front wall 17, and the two side walls are the side-symmetrical mode water-cooled wall 55.

[0123] The lower end of the auxiliary combustion chamber is the air distribution plate 4, the upper end is the two-pass downwardly tapered flue outlet 8 and the three-pass flue upper end to the water vapor cooling roof 58, the front wall is the two-pass downwardly tapered flue rear wall, the rear wall is the shaft front wall 17, and the two side walls are the side-symmetrical mode water-cooled wall 55.

[0124] The lower end of the auxiliary combustion chamber is the air distribution plate 4, the upper end is the two-pass downwardly tapered flue outlet 8 and the three-pass flue upper end to the water vapor cooling roof 58, the front wall is the two-pass downwardly tapered flue rear wall, the rear wall is the shaft front wall 17, and the two side walls are the side-symmetrical mode water-cooled wall 55.

[0125] The smoke path of the super large power station boiler of the embodiment: the flue gas passes through the front and rear symmetrical two flue gas outlets 60, 61 of the trousers-shaped furnace, makes a 180-degree turn and goes straight down into the front and rear symmetrical two two-return high-temperature accelerated downwardly tapered flues 37, 38 and 53, 16; the flue gas directly collides with the air distribution plate at the lower end of the three times expansion of the auxiliary combustion chamber, so that a large amount of solid particles naturally settle on the air distribution plate area of the auxiliary combustion chamber, the fine particles that do not settle on the air distribution plate continue to burn in the front and rear symmetrical two auxiliary combustion chambers, the flue gas that is carried by the airflow and continues to burn at low speed goes through the front three-return upward flues of the furnace, passes through the high-temperature superheater 39, 44, and is forced to separate part of the fly ash by the flow separation, and then the flue gas goes through the gap of the furnace top water wall tube, goes to the rear part, goes down into the shaft flue 47, passes through the superheater and the economizer, and is washed by the convection heat transfer, goes into the dust collector through the smoke outlet 52, and is discharged into the atmosphere by the induced draft fan after the flue gas is staticized.

[0126] The boiler body structure of the embodiments 1 to 2 can be designed according to the invention patent disclosed and authorized by the inventor before.

[0127] The fuel inlet, desulfurizer inlet, slag discharge port, material inlet, air distribution plate, primary air and secondary air inlet, flue gas outlet of the furnace, furnace door, explosion door, observation hole, measurement hole, and maintenance hole of the embodiments 1 to 2 are designed according to the existing technical standards.

[0128] The furnace water wall tube water circulation, separator water wall tube water circulation, shaft water wall tube water circulation, steel frame and heat insulation, superheater, reheater, economizer, air preheater, etc. of the embodiments 1 to 2 are designed according to the existing general technical standards.

[0129] The upper communication gas guide pipe and the lower communication downcomer of the natural circulation steam boiler and the power station boiler are matched with the downcomer of the vertical and horizontal lower header and the gas guide pipe of the vertical and horizontal upper header. The hot water boiler is designed according to the existing general technical standards.

[0130] The forced circulation steam boiler and the power station boiler are designed according to the existing mature technology.

[0131] The natural circulation hot water boiler and the forced circulation hot water boiler are designed according to the existing mature technology.

[0132] All the different structures, different components and different points in the embodiments 1 to 2 can be integrated, optimized and combined into new furnace types.

[0133] Although the basic principles and preferred embodiments of the application have been described above in connection with the accompanying drawings, the application is not limited to the above-described specific embodiments, but rather the above-described specific embodiments are merely illustrative, and are not restrictive, and any person skilled in the art can make many forms under the inspiration of the application without departing from the purpose of the application and the scope of protection of the claims, and these all belong to the protection scope of the application.

Claims

1. A BFB / CFB boiler flow state, combustion reconstruction, energy saving, efficiency increasing, low emission and large-scale structure and method, characterized in that, The technical solutions comprise the following: (1) A new combustion and gas-solid separation system of BFB / CFB boiler, The features include: one to two main combustion chamber furnaces, one to two two-return downward tapered flues, and one to two auxiliary combustion chamber three-return flues; wherein, the bottom of the auxiliary combustion chamber is provided with a wind distribution plate; The two-return flue inlet is communicated with the main combustion chamber furnace outlet, which is a tapered super-long downward flue, used for guiding and conveying the suspended solid materials in the upper part of the main combustion chamber to the wind distribution plate area of the auxiliary combustion chamber through inertia and gravity; The three-return flue inlet is communicated with the two-return flue outlet, which is configured as a super-long upward channel, and is used as an auxiliary combustion chamber at the same time, and the length is configured to make the unburned fine particle fly ash have sufficient residence time to complete the burnout in the suspended state; (2) Flow state reconstruction and combustion reconstruction of BFB / CFB boiler; (3) Structure and working process of low-resistance high-efficiency multifunctional inertia-gravity gas-solid separation technology shared by BFB / CFB boiler; (4) Energy-saving and efficiency-increasing structure and method of flow state and combustion reconstruction of BFB / CFB boiler; (5) Ultra-low emission method of flow state and combustion reconstruction of BFB / CFB boiler: (6) Large-scale and super-large-scale implementation method of flow state and combustion reconstruction of BFB / CFB boiler.

2. The BFB / CFB boiler flow state reconstruction according to claim 1, characterized in that: The BFB boiler flow state reconstruction is characterized in that: the rear wall water cooling wall of the main combustion chamber furnace is bent and inclined forward at an appropriate position in the upper half and gradually shrinks to the furnace outlet to gradually increase the flue gas flow velocity in the dilute phase zone, realize heat concentration and strengthen combustion, and expand the cross section of the two-return flue inlet to reduce the flow resistance. The BFB boiler combustion reconstruction is characterized in that: the buried pipe heating surface of the traditional BFB boiler and the ash bucket at the furnace outlet for collecting fly ash are removed; the space between the rear wall water cooling wall of the main combustion chamber furnace and the front wall water cooling wall of the shaft is designed as a two-return and three-return flue; wherein, the inlet of the two-return downward tapered flue is communicated with the flue gas outlet of the main combustion chamber; The front wall of the two-return flue and the rear wall of the main combustion chamber are shared walls, and the rear wall and the three-return flue are shared walls; the upper end of the two-return downward tapered flue is at 8 / 10 of the height H of the auxiliary combustion chamber wind distribution plate, which is the outlet, and the outlet is communicated with the inlet of the three-return flue at the same time; from the two-return flue outlet to the height H of the 2 / 10 height area of the wind distribution plate, plus the whole three-return flue, together constitute the auxiliary combustion chamber. The CFB boiler flow state reconstruction is characterized in that: the running flow velocity in the dense phase zone does not exceed the low-ratio circulating fluidized velocity; the front and rear wall water cooling walls of the main combustion chamber panty-shaped furnace are bent and inclined inward at an appropriate position in the upper half and gradually shrink to the flue gas outlet of the furnace, so that the flue gas enters the two-return downward tapered flue at a flow velocity of about 5 m / s, and accelerates to 7-9 m / s at the outlet and then enters the auxiliary combustion chamber area; the flue gas flow velocity in the three-return flue is controlled at 2-3 m / s. The CFB boiler combustion reconstruction is characterized in that: the cyclone separator (cyclone) at the upper part of the front end of the trousers-shaped furnace and the material circulation return system at the lower part are removed; the original cyclone separation area is replaced by a sub-combustion chamber composed of a two-return downward tapered flue and a three-return upward flue; wherein the front wall of the two-return flue and the rear wall of the three-return flue are shared walls, and the rear wall and the front wall of the trousers-shaped furnace are shared walls; the two-return flue inlet is located at a height of 8 / 10 of the air distribution plate H, which is the outlet, and the outlet is also the inlet of the three-return flue; from the outlet to a height of 2 / 10 of the air distribution plate H, together with the whole three-return flue, they jointly constitute the sub-combustion chamber. According to the CFB boiler combustion reconstruction of claim 1, the space from the original cyclone separator at the rear end of the trousers-shaped furnace to the front wall of the shaft is designed as a two-return flue and a three-return flue; wherein the front wall of the two-return flue and the rear wall of the trousers-shaped furnace are shared walls, the rear wall and the front wall of the three-return flue are shared walls, and the rear wall of the three-return flue and the front wall of the shaft flue are shared walls; the two-return flue inlet is located at a height of 8 / 10 of the air distribution plate H, which is the flue gas outlet, and is in communication with the inlet of the three-return flue; from the flue gas outlet to a height of 2 / 10 of the air distribution plate H, together with the whole three-return flue, they jointly constitute the sub-combustion chamber.

3. The BFB / CFB boiler shared low-resistance high-efficiency multifunctional inertial gravity gas-solid separation technology according to claim 1, characterized in that: The gas-solid separation does not depend on any special separation device or separation element, but is naturally constituted by the high-temperature water-cooled inertial and gravitational settling separator in the large cross-section heating surface space composed of the two-return downward tapered flue and the three-return upward flue of the sub-combustion chamber; the dust-containing flue gas undergoes multiple changes in flow direction, flow rate and flow path after the furnace outlet: in the two-return downward tapered flue, the flue gas is turned by 180 degrees and flows downward at the same speed, the blowing force of the airflow and the gravity of the solid naturally improve the efficiency of the combustible material separating from the air distribution plate; when entering the three-return flue, the sudden expansion reduces the speed, promoting the settling of fine particles; the two-return flue outlet and the three-return flue inlet are arranged at a suitable position close to the air distribution plate of the sub-combustion chamber, so that the separated material falls directly into the air distribution plate area; the material realizes the cooperative combustion of boiling combustion and suspension combustion on the air distribution plate of the sub-combustion chamber; the three-return flue provides sufficient length to ensure sufficient flue gas residence time, realizing complete combustion of fine particles; this structure not only realizes efficient gas-solid separation, but also has the functions of carbon burnout, radiation and convection heat transfer.

4. The BFB / CFB boiler energy saving and efficiency increasing structure and method according to claim 1, characterized in that, The following energy-saving and efficiency-improving technical solutions are included: (1) Energy-saving structure and method, taking a 600 MW grade CFB boiler as an example: (a) Remove the traditional cyclone separator and its supporting material circulation return system; can save 15%-25% of the total machine refractory and steel frame. (b) Adopt a seven-return water-cooled flue structure to reduce the overall height of the boiler by about 40%; (c) Through the integrated arrangement of the main combustion chamber, the two-return flue and the three-return flue, two transverse partition walls and one longitudinal flue are reduced, thereby saving the amount of refractory and supporting steel frame; wherein the three measures of (a), (b) and (c) work together, and theoretically more than 50% of the total amount of refractory and steel frame structure of the whole machine can be saved; (2) Synergistic structure and method, taking a 600 MW class CFB boiler as an example: (a) Using the new low-resistance high-efficiency multi-functional inertial gravity gas-solid separation technology of claim 1, the local maximum flue gas flow rate is less than or equal to 9 m / s, which significantly reduces the flow resistance compared to the traditional cyclone separator (design flow rate about 30 m / s), and the system pressure drop is reduced by more than 30%; (b) The power consumption of the return material circulating system is cancelled, and the auxiliary combustion chamber takes over about 30% of the primary air load through the air supply of the air distribution plate, while the secondary air of the original main combustion chamber is distributed to the auxiliary combustion chamber for use, which comprehensively reduces the primary air fan energy consumption by about 40%; (c) The auxiliary combustion chamber is designed as a 30-meter-high boiling combustion space with a fluidization speed of 2-3 m / s, which prolongs the residence time of fine particles, controls the carbon content of fly ash below 0.5%, improves the combustion efficiency, and is beneficial to improve the boiler thermal efficiency; (d) The five-mode water-cooled wall transverse wall adopts a double-sided heating structure to enhance the heat transfer performance, reduce the risk of ash accumulation and local overheating, reduce the maintenance frequency, and theoretically reduce the maintenance and repair cost by 70%, and prolong the service life of the boiler by 3-5 years; Wherein, (a) to (d) each measure constitutes a technical path of energy saving and efficiency improvement, and realizes a comprehensive substantial reduction of power consumption, coal consumption and maintenance cost.

5. The ultra-low emission method of BFB / CFB boiler of claim 1. The features include: (1) Flue dust control: using low resistance and high efficiency inertial gravity gas-solid separation technology, the initial emission concentration of BFB / CFB boiler flue dust can be controlled at 1200-1500 mg / m 3 . (2) Nitrogen oxide (NOx) control: Achieve original ultra-low emission of NOx through high-temperature low-oxygen combustion technology. (3) Carbon dioxide (CO2) control: Coupling oxygen-enriched combustion technology to produce high-concentration CO2 flue gas, combined with carbon capture, utilization and storage (CCUS) technology, to achieve near-zero CO2 emission.

6. The method of large- and super-large-sized BFB / CFB boiler according to claim 1, characterized in that, Including the following technical paths: (a) By reducing the particle size of fuel particles to improve the stability of combustion and the efficiency of gas-solid mixing, thereby supporting the expansion of boiler capacity; Wherein, the BFB boiler uses 0-10 mm fuel particles when the capacity is 100-300 MW; CFB boiler uses 0-2 mm fuel particles when the capacity is 1000-1400 MW; (b) Fine control of fuel particle size makes the circulating fluidization state more uniform, improves combustion efficiency, and controls fly ash carrying capacity, supporting the development of ultra-large capacity boilers and realizing the full replacement of coal-fired boilers in 600 MW and above class units; (c) The fuel crushing energy consumption is less than 8 kWh / t, which is about 83% lower than the traditional coal powder preparation (about 48 kWh / t), significantly reducing the plant power rate; (d) BFB and CFB boilers share the core principle of fluidized combustion, by adjusting the fuel particle size, wind speed and bed pressure, the operation mode can be continuously transitioned and converted: The BFB boiler can be converted to CFB operation mode by reducing the fuel particle size and increasing the wind speed; The CFB boiler presents BFB operation characteristics when burning coarser fuel and reducing wind speed; (e) the large-scale method relies on the "fine fuel preparation-high efficiency gas-solid separation-dual bed synergistic combustion" integrated architecture, which enables the CFB boiler to have the technical capability to develop into a 1000-1400 MW ultra-large power plant boiler, and ends the dominance of the pulverized coal boiler in the field of ultra-large units.

7. A fluidized bed boiler system according to claim 1, characterized in that The system is a dual-inertial fluidized bed inertial-gravity separator (DIFB-IGS) system, comprising: The main combustion chamber constitutes the core part of the switchable fluidized dual-inertial fluidized bed (DIFB), which realizes the dynamic switching of the BFB (bubbling fluidized bed) and CFB (circulating fluidized bed) operation modes by adjusting the water-cooled wall structure parameters, operating wind speed and bed pressure; The inertial-gravity separator (IGS) is composed of a two-return flue and a three-return flue, which realizes high-efficiency gas-solid separation through two changes in the flow direction of flue gas, one-time gas-solid two-phase downward co-flow and flow rate mutation (two-return flue outlet flue gas velocity 7-9 m / s, three-return flue flue gas velocity 2-3 m / s); The auxiliary combustion chamber receives the coarse particulate material separated by the IGS, and realizes in-situ fluidized combustion through the air distribution plate, so that the unburned particles complete suspended combustion in the three-return flue of the auxiliary combustion chamber, thereby reducing the carbon content of fly ash; the lower end of the two-return flue and the three-return flue is connected to the air distribution plate of the auxiliary combustion chamber, and the height of the inlet and outlet is designed to meet the flue gas velocity of 7-9 m / s for 90-degree turning of the flue gas into the three-return flue, so as to forcibly disturb, loosen and mix the gas-solid two-phase and the material of the air distribution plate and supplement oxygen, while maximizing the residence time of combustible materials in the auxiliary combustion chamber (≥10 seconds).

8. The DIFB-IGS system of claim 7, wherein, The three-return flue of the auxiliary combustion chamber of the inertial-gravity separator (IGS) adopts an expanded design, and its cross-sectional area is more than 3 times that of the outlet cross-sectional area of the two-return flue, so that the flue gas velocity in the three-return flue is reduced to 2-3 m / s, realizing: (a) enhancing the effect of particle gravity sedimentation and improving the separation efficiency of fine particles; (b) prolonging the flue gas residence time to ≥10 seconds to ensure complete combustion of fly ash residual carbon; (c) reducing the system flow resistance by more than 30% as claimed in claim 4, forming a technical echo.

9. The DIFB-IGS system of claim 7, wherein, The main combustion chamber, auxiliary combustion chamber and inertial-gravity separator (IGS) are integrated structures, comprising: The shared main combustion chamber rear wall and the two-return flue front wall, the two-return flue rear wall and the three-return flue front wall, and the three-return flue rear wall and the vertical shaft flue front wall share a wall body; The five-mode water-cooled wall transverse wall adopts a double-sided heating design to realize efficient heat conduction; By sharing the air distribution system and flue process, the amount of refractory material is reduced by more than 30%, and the manufacturing cost is reduced; Optimizing the heat conduction path improves the boiler thermal efficiency by 1-2 percentage points, while simplifying the installation and maintenance process.

10. The BFB / CFB boiler system of claim 1, wherein, The boiler adopts a natural circulation water-cooled wall system, comprising: The exhaust pipe connected to the top of the longitudinal and transverse header communicates with a plurality of longitudinal air guide branch pipes; The water vapor cooling roof is provided with a through-hole matched with the size of the exhaust pipe to ensure smooth air flow; The front and rear ends of the drum arranged at the top of the boiler body facilitate the arrangement of the longitudinal downcomer area, realizing the optimized arrangement of the natural circulation.

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