CN109297015B - Coupling pressurization oxygen-enriched combustion device of circulating fluidized bed/bubbling fluidized bed - Google Patents

Coupling pressurization oxygen-enriched combustion device of circulating fluidized bed/bubbling fluidized bed Download PDF

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Publication number
CN109297015B
CN109297015B CN201811010972.3A CN201811010972A CN109297015B CN 109297015 B CN109297015 B CN 109297015B CN 201811010972 A CN201811010972 A CN 201811010972A CN 109297015 B CN109297015 B CN 109297015B
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hearth
fluidized
fluidized bed
heat exchanger
bubbling
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CN109297015A (en
Inventor
陈晓平
昝海峰
吴影
刘道银
马吉亮
梁财
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Southeast University
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Southeast University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F23C10/02—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed
    • F23C10/04—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone
    • F23C10/08—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone characterised by the arrangement of separation apparatus, e.g. cyclones, for separating particles from the flue gases
    • F23C10/10—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone characterised by the arrangement of separation apparatus, e.g. cyclones, for separating particles from the flue gases the separation apparatus being located outside the combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F23C10/16—Fluidised bed combustion apparatus specially adapted for operation at superatmospheric pressures, e.g. by the arrangement of the combustion chamber and its auxiliary systems inside a pressure vessel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F23C10/18—Details; Accessories
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F23C10/18—Details; Accessories
    • F23C10/20—Inlets for fluidisation air, e.g. grids; Bottoms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F23C10/18—Details; Accessories
    • F23C10/22—Fuel feeders specially adapted for fluidised bed combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
    • F23L7/007—Supplying oxygen or oxygen-enriched air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/06041—Staged supply of oxidant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/10006—Pressurized fluidized bed combustors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Abstract

The invention discloses a circulating fluidized bed/bubbling fluidized bed coupling pressurization oxygen-enriched combustion device, which comprises a circulating fluidized bed/bubbling fluidized bed coupling hearth, an air chamber, an air distribution plate, a cyclone separator, a material returning device, an external heat exchanger, a buried pipe heating surface and a screen type heating surface, wherein the hearth adopts graded air supply and graded coal supply, the buried pipe heating surface is arranged in a dense-phase region, and an outlet of a dilute-phase region is connected to the cyclone separator; the cyclone separator separates solid materials in the flue gas at the outlet of the hearth and the solid materials enter the material returning device and the external heat exchanger. The device of the invention is suitable for the combustion of solid fuel under the conditions of pressurization and high inlet oxygen concentration, and has the advantages of a bubbling fluidized bed and a circulating fluidized bed. The problem of limited arrangement of the heating surface can be effectively solved by arranging the buried pipe heating surface with high volume utilization rate in the bubbling fluidization area at the lower part of the hearth, and the furnace temperature and the temperature distribution in the furnace can be effectively controlled by graded coal feeding, graded air feeding and graded material returning.

Description

Coupling pressurization oxygen-enriched combustion device of circulating fluidized bed/bubbling fluidized bed
Technical Field
The invention relates to a circulating fluidized bed/bubbling fluidized bed coupling pressurization oxygen-enriched combustion device, relates to the technical field of circulating fluidized bed combustion, and particularly relates to the technical field of pressurization circulating fluidized bed oxygen-enriched combustion.
Background
The combustion of fossil fuels necessarily produces CO2As representative greenhouse gases, greenhouse gases emitted in large quantities have had a serious impact on global climate. The thermal power station is an important industry for consuming fossil energy, and the installed capacity of the coal-fired power station in China accounts for over 70 percent in the power station industry in China. Therefore, the urgent need of our country is to find a suitable oneCO for coal-fired power plants2A trapping technique. In existing coal-fired power stations CO2In the trapping technology, oxygen-enriched combustion (also called O)2/CO2Combustion) technology is widely concerned with its advantages of maturity, reliability, good economy and the like, and the coal-fired oxygen-enriched combustion technology is divided into two types, namely fluidized bed oxygen-enriched combustion technology and pulverized coal furnace oxygen-enriched combustion technology. The oxyfuel combustion being O obtained by air separation2And partial circulating smoke replaces air and fuel to organize combustion, and CO in the discharged smoke is greatly improved2To achieve CO2A trapping technique. Meanwhile, the oxygen-enriched combustion technology replaces nitrogen in air with circulating flue gas, so that NOx generated in the fuel combustion process is completely from fuel nitrogen, thermal NOx and rapid NOx are hardly generated, and the emission of NOx can be reduced from the source.
In recent years, with the continuous and deep research of the oxygen-enriched combustion technology, a plurality of stages of progress have been made, the average oxygen concentration at the entrance of a hearth is developed to be more than 50% from 25% -28% of the first generation, but a plurality of problems and challenges exist in the aspects of engineering application and the like. The increase of the oxygen concentration reduces the amount of the recirculated flue gas, so that the energy consumption of the circulating fan is reduced, but the heat brought out of the hearth by the recirculated flue gas is reduced, the volume and the sectional area of the hearth are reduced, and the difficulty of the arrangement of the heating surface is increased. In addition, the first generation oxygen-enriched combustion technology adopts a normal pressure combustion mode, a hearth operation pressure and air separation device and CO2Pressure variations between purification and compression units can also consume significant amounts of energy. The pressurized oxygen-enriched combustion technology is adopted, so that the operating pressure of the hearth is properly improved, energy loss caused by pressure change can be partially reduced, the condensing temperature of the water vapor is improved by pressurization, latent heat released by condensation of the water vapor can be more effectively utilized, and the efficiency of a power station is improved. Therefore, the development of the supercharged oxygen-enriched combustion technology becomes the mainstream trend. However, the adoption of the pressurized oxygen-enriched combustion technology further reduces the volume of the hearth, and the problems of heating surface arrangement and hearth temperature control are more prominent, thereby seriously restricting the popularization and the commercial application of the pressurized oxygen-enriched combustion technology, in particular to the pressurized circulating fluidized bed oxygen-enriched combustion technology.
In order to solve the outstanding problems of heating surface arrangement and difficult hearth temperature control of the pressurized circulating fluidized bed oxygen-enriched combustion technology, the invention provides an innovative circulating fluidized bed/bubbling fluidized bed coupling pressurized oxygen-enriched combustion device, which adopts a fuel grading feeding technology, a circulating ash grading material returning technology and a hearth grading air distribution technology, organically couples a circulating fluidized bed and a bubbling fluidized bed, and can effectively control hearth combustion share distribution and furnace temperature distribution, and the technology is not reported yet.
Disclosure of Invention
Aiming at the limitation of the prior art, the invention provides a pressurized circulating fluidized bed/bubbling fluidized bed coupled pressurized oxygen-enriched combustion device. The device combines the advantages of the bubbling fluidized bed, and the buried pipe heating surface is additionally arranged at the lower part of the bubbling fluidized bed, so that the problem of difficult arrangement of the oxygen-enriched combustion heating surface of the pressurizing circulating fluidized bed is effectively solved. Meanwhile, the technology of graded air distribution, graded coal supply and circulating ash grade return material is adopted to control the combustion share distribution and the temperature distribution of the hearth.
in order to solve the technical problems, the invention adopts the technical scheme that:
A circulating fluidized bed/bubbling fluidized bed coupling pressurization oxygen-enriched combustion device comprises a pressurization furnace hearth, wherein the pressurization furnace hearth is divided into a bubbling fluidized state furnace hearth, a transition fluidized state furnace hearth and a rapid fluidized state furnace hearth which are sequentially connected, an air distribution plate is arranged at the bottom of the bubbling fluidized state furnace hearth, a lower air supply port is formed in an air chamber, a buried pipe heating surface is arranged in the bubbling fluidized state furnace hearth, and a lower coal supply port is formed in the outer wall of the bubbling fluidized state furnace hearth; the transition fluidized state hearth is provided with a middle coal supply port and a middle air supply port; an upper coal supply port and an upper air supply port are formed in the part, close to the transition fluidized state furnace, of the rapid fluidized state furnace, a screen type heating surface is installed in the rapid fluidized state furnace, an outlet of the rapid fluidized state furnace is connected with a cyclone separator through a horizontal flue, an upper outlet of the cyclone separator is connected with a tail flue through a central cylinder, a lower outlet of the cyclone separator is connected with a discharging pipe, the discharging pipe is provided with a material returning device and an external heat exchanger in a shunting manner, and a pipeline, connected with the discharging pipe, of the external heat exchanger is an external heat exchanger feeding pipe; the external heat exchanger is respectively provided with a first heat exchanger pipeline connected with the bubbling fluidized-state hearth, a second heat exchanger pipeline connected with the transition fluidized-state hearth, and a third heat exchanger pipeline connected with the fast fluidized-state hearth, and the material returning device is respectively provided with a first material returning pipeline connected with the first heat exchanger pipeline, a second material returning pipeline connected with the second heat exchanger pipeline, and a third material returning pipeline connected with the third heat exchanger pipeline.
As a further preferable mode, the cross-sectional area of the bubbling fluidized-state furnace is larger than the cross-sectional areas of the transition fluidized-state furnace and the fast fluidized-state furnace.
As a further preferable scheme, the heating surface of the buried pipe is a cold water buried pipe with high volume utilization rate.
As a further preferable scheme, the fuel feeding inlets of the pressurized hearth are respectively arranged in a bubbling fluidized-state hearth, a transition fluidized-state hearth and a fast fluidized-state hearth in three stages along the height. Feeding coarse particles obtained by screening the fuel into a bubbling fluidized hearth through a feed inlet at the bottom of the hearth; the screened fine fuel is fed into the hearth through feed inlets in the middle and upper parts of the hearth.
As a further preferable scheme, the material returning device and the external heat exchanger respectively return solid materials to a bubbling fluidized hearth, a transition fluidized hearth and a fast fluidized hearth of the hearth along the height of the hearth in three stages.
Through the technical scheme, the beneficial effects of the device disclosed by the invention are as follows:
(1) The pressurized circulating fluidized bed device is suitable for combustion under high oxygen concentration, and can reduce the volume of the boiler body and the auxiliary machine, thereby reducing the boiler investment and the operation cost.
(2) Oxygen and circulating flue gas are introduced at different heights of the hearth to realize graded oxygen supply, and combustion share distribution and hearth temperature distribution are effectively regulated and controlled by matching with a fuel graded feeding technology; the amount of circulating flue gas can be reduced according to the needs, and the energy consumption of the circulating fan is reduced.
(3) The device supplements the deficiency of the heating surface of the hearth and adjusts the temperature of the hearth through the external heat exchanger, and can bring heat into the external heat exchanger to be absorbed by adjusting the circulating ash amount, so as to solve the problem that the temperature of the hearth is difficult to control under the condition of boosting and oxygen enrichment.
(4) The bubbling section of the supercharged hearth of the device adopts the buried pipe heat exchanger to increase the heat exchange surface of the hearth, the heat exchange quantity of the combustion device is increased to control the temperature and the temperature distribution of the hearth of the supercharged circulating fluidized bed, and the problems of limited arrangement of the heating surface and insufficient heat absorption of the heating surface in the furnace caused by reduction of the hearth size of the circulating fluidized bed in a supercharged environment can be effectively solved.
(5) The device realizes the distribution of combustion share control along the furnace height through grading coal supply, grading material return and grading oxygen supply, so that the fuel can be fully and stably combusted. The purpose of controlling the furnace temperature and the temperature distribution in the furnace chamber is achieved by further combining the arrangement of the heating surfaces.
(6) The device has strong fuel adaptability and is suitable for the oxygen-enriched combustion of pressurized fluidized beds of various grades of coal, biomass and other fossil fuels.
Drawings
FIG. 1 is a schematic structural view of the present invention;
wherein, 101-bubbling fluidized hearth; 102-a transition fluidized state hearth; 103-fast fluidized hearth; 2-an air chamber; 3-air distribution plate; 4-buried pipe heating surface; 5-screen type heating surface; 6-a cyclone separator; 7-a blanking pipe; 8-a central cylinder; 9-a material returning device; 10-external heat exchanger feed pipe; 11-internal heating surface of external heat exchanger; 12-external heat exchanger; 13-lower air supply port; 14-lower coal supply port; 15-a middle coal supply port; 16-middle air supply port; 17-upper coal supply port; 18-upper air supply opening.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings in combination with the specific embodiments. The drawings described herein are simplified for illustration purposes only. The number, shape and size of the components in the drawings can be increased, decreased or modified according to the actual application. Other aspects of practice or use can be made of the present invention, and various changes and modifications can be made without departing from the spirit and scope of the invention as defined in the following claims.
The inspiration of the invention comes from the technical defects of the prior pressurized oxygen-enriched combustion technology, and provides a pressurized circulating fluidized bed/bubbling fluidized bed coupled pressurized oxygen-enriched combustion device on the basis of the technical defects. The device is suitable for combustion under high-pressure high-oxygen concentration at the inlet, greatly reduces the volume of the boiler body and the auxiliary machine, simultaneously increases the arrangement of the heating surface in the boiler, can effectively solve the problem of limited arrangement of the heating surface caused by the reduction of the pressurized boiler body, and improves the heat exchange quantity in the pressurized hearth by reasonably matching and regulating the combustion share in the hearth and the temperature distribution in the boiler through graded coal supply, graded air supply, graded material return and the heating surface, thereby ensuring safe and stable operation.
A circulating fluidized bed/bubbling fluidized bed coupling pressurization oxygen-enriched combustion device comprises a pressurization hearth, wherein the periphery of the pressurization hearth can be formed by membrane walls, and the bubbling fluidized-state hearth 101, a transition fluidized-state hearth 102 and a rapid fluidized-state hearth 103 are sequentially connected from bottom to top in structure, wherein the bubbling fluidized-state hearth 101 has a larger cross-sectional area and is in a bubbling fluidized state; the fast fluidized furnace 103 has a smaller cross-sectional area to implement a fast fluidized state, and shows a structural layout with a narrow top and a wide bottom.
The bottom of the bubbling fluidized state hearth 101 is provided with an air distribution plate 3, an air chamber 2 is provided with a lower air supply port 13, a buried pipe heating surface 4 is arranged in the bubbling fluidized state hearth 102, and the outer wall of the bubbling fluidized state hearth is provided with a lower coal supply port 14.
The furnace hearth adopts graded air supply and graded coal supply, and a middle coal supply port 15 and a middle coal supply port 16 are arranged on the transition fluidized state furnace hearth 102; an upper coal supply port 17 and an upper air supply port 18 are formed in the part, close to the transition fluidized state furnace 102, of the rapid fluidized state furnace 103, a screen type heating surface 5 is installed in the rapid fluidized state furnace 103, a cyclone separator 6 is arranged at the position of an opening, leading to the outside, of the rapid fluidized state furnace 103, an upper outlet of the cyclone separator 6 is connected with a tail flue through a central cylinder, a lower outlet of the cyclone separator 6 is connected with a discharging pipe 7, a material returning device 9 and an external heat exchanger 12 are arranged in a shunting manner on the discharging pipe 7, and a pipeline, connected with the discharging pipe 7, of the external heat exchanger 12 is an external; the external heat exchanger 12 is respectively provided with a first heat exchanger pipeline connected with the bubbling fluidized state hearth 101, a second heat exchanger pipeline connected with the transition fluidized state hearth 102, and a third heat exchanger pipeline connected with the fast fluidized state hearth 103, and the material returning device 9 is respectively provided with a first material returning pipeline connected with the first heat exchanger pipeline, a second material returning pipeline connected with the second heat exchanger pipeline, and a third material returning pipeline connected with the third heat exchanger pipeline.
The heat transfer coefficient of the bubbling fluidization area is 250W/m2℃-300W/m2The temperature is far higher than the heat transfer coefficient (100W/m) in other fluidized circulating fluidized bed furnaces2℃-150W/m2C), 3m-5m of high water-cooling buried pipe is arranged inside to form a buried pipe heating surface 4, and the arrangement of the heating surface of the dense-phase region of the hearth is increased to increase the heat exchange capacity of the hearth. The upper fast fluidization region may be provided with a screen heat exchanger 5 to supplement the heating surface.
The flue gas containing the circulating materials generated by the pressurized hearth enters the cyclone separator 6 through the outlet at the top of the pressurized hearth for gas-solid separation treatment. The separated flue gas enters the tail heating surface for heat exchange through the central cylinder 8 at the upper part of the cyclone separator. And the separated circulating material enters a material returning device 9 or an external heat exchanger 12 through a blanking pipe 7.
the material returning device 9 is of a U-shaped structure with a membrane type water-cooled wall. The material returning device and the external heat exchanger return solid materials to the hearth in three stages, specifically, one side of the material returning device 9 is connected with the hearth through a three-stage outlet, and a higher-stage outlet (a third material returning pipeline) is connected with a third pipeline of the heat exchanger to lead to the upper part of the pressurized hearth (the fast fluidized hearth 103); the middle-stage outlet (a second return material pipeline) is connected with a second pipeline of the heat exchanger to lead to a transition section (a transition fluidized state hearth 102) of the bubbling fluidization area and the fast fluidization area of the pressurized hearth; the lower outlet (first return duct) is connected to the heat exchanger first duct to lead to the lower part of the pressurized furnace (bubbling fluidized bed furnace 101). The structure realizes the regulation and control of the thermal cycle ash returning process, and achieves the purpose of controlling the temperature distribution in the furnace.
The outlet at the other side of the blanking pipe 7 is connected with an external heat exchanger 12 through an external heat exchanger feeding pipe 10, and the amount of ash entering the external heat exchanger 12 is adjusted through a needle valve on the blanking pipe 7. Furthermore, the periphery of the external heat exchanger 12 is composed of membrane water walls, fluidized air is recirculated flue gas, the temperature of the recirculated ash at the inlet is 750-900 ℃, and the temperature of the recirculated ash at the outlet is 300-400 ℃. The heating surfaces 11 arranged on the external heat exchanger are an evaporator, a superheater and a reheater. The whole external heat exchanger not only increases the heat exchange surface of the whole structure and increases the heat exchange quantity, but also considers the ash conveying function of the main circulation loop.
The external heat exchanger 12 is provided with a third-stage outlet, and a higher-stage outlet (a third pipeline of the heat exchanger) is connected with the upper part of the pressurized hearth (the fast fluidized hearth 103); a middle-stage outlet (a second pipeline of the heat exchanger) is connected with a transition section (a transition fluidized state hearth 102) of the bubbling fluidization area and the fast fluidization area of the supercharged hearth; a lower outlet (a first pipeline of the heat exchanger) is connected with the lower part of the pressurized hearth (a bubbling fluidized-state hearth 101); the coarse particles obtained by screening the fuel are added into the hearth through the feed inlet at the bottom of the hearth, the fine fuel obtained by screening is added into the hearth through the feed inlets at the middle part (transition zone) and the upper part (fast fluidization zone) of the hearth, and the cold circulation ash grade material return is realized through the structure, so that the aim of controlling the temperature distribution in the furnace is fulfilled.
The pressurized oxygen-enriched circulating fluidized bed device is divided into three-stage coal feeding and three-stage air distribution along the height direction of a pressurized hearth. The primary air separated into oxygen and recirculated flue gas is fed into the pressurized furnace from the lower air supply opening 13. Secondary air is fed from a middle air supply port 16 at the transition section of the bubbling fluidization area and the fast fluidization area of the supercharged hearth. Tertiary air (over-fired air) is fed from an upper air supply port 18 in the fast fluidized zone. The three-level coal supply ports are respectively matched with the three-level air distribution ports, after the fuel is roughly screened, the fuel with a larger particle size is fed into the lower coal supply port 14, and the fuel with a smaller particle size is fed into the upper coal supply port 17. After the graded air distribution and the graded coal feeding, the combustion share of each area in the hearth can be flexibly adjusted according to the actual situation, and the air distribution proportion is further adjusted by combining the arrangement of the heating surface in the furnace, so that the circulating flue gas quantity is reduced while the temperature distribution of the hearth is controlled, and the energy consumption of a circulating fan is reduced.
The fuel is respectively fed into a pressurized hearth (a bubbling fluidized hearth 101, a transitional fluidized hearth 102 and a fast fluidized hearth 103) through three-level coal feeding ports for combustion, and the generated flue gas realizes gas-solid separation in the cyclone separator 6. Gas enters a tail flue through a central cylinder 8, and separated solid materials enter a material returning device 9 and an external heat exchanger 12 through a blanking pipe 7; and the solid materials are sent back to different sections of the pressurizing hearth through the three-stage material return pipelines.
The device of the invention is suitable for the combustion of solid fuel under the conditions of pressurization and high inlet oxygen concentration, and has the advantages of a bubbling fluidized bed and a circulating fluidized bed. The problem that the arrangement of a heating surface is limited due to the fact that the size of a furnace body is greatly reduced under the conditions of pressurization and high inlet oxygen concentration can be effectively solved by arranging the buried pipe heating surface with high volume utilization rate in the bubbling fluidization area at the lower portion of the hearth, and the furnace temperature and the temperature distribution in the furnace are effectively controlled through graded coal feeding, graded air feeding and graded material returning, so that efficient, environment-friendly, safe and stable operation of the pressurized oxygen-enriched combustion device is guaranteed, the energy consumption of a circulating fan is effectively reduced by reducing the amount of circulating flue gas, and the economical efficiency of the pressurized oxygen-enriched combustion system is improved; through the comprehensive regulation and control of the coal feeding amount of each stage, the air volume and the oxygen concentration of each stage, the ash amount entering the external heat exchanger and the material returning device, and the three-stage material returning amount of the material returning device and the external heat exchanger along different heights of the hearth, the distribution of the combustion share of the fuel along the height of the hearth is reasonably matched with the heating surface of the hearth, and the high-efficiency, environment-friendly, safe and stable operation of the pressurized oxygen-enriched combustion device is realized while the circulating flue gas amount is effectively reduced.
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (5)

1. The utility model provides a circulating fluidized bed/bubbling fluidized bed coupling pressurization oxygen boosting burner which characterized in that: the device comprises a pressurized hearth, wherein the pressurized hearth is divided into a bubbling fluidized-state hearth (101), a transition fluidized-state hearth (102) and a fast fluidized-state hearth (103) which are sequentially connected, an air distribution plate (3) is arranged at the bottom of the bubbling fluidized-state hearth (101), a lower air supply port (13) is arranged on an air chamber (2), a buried pipe heating surface (4) is arranged in the bubbling fluidized-state hearth (101), and a lower coal supply port (14) is arranged on the outer wall of the bubbling fluidized-state hearth; a middle coal supply port (15) and a middle air supply port (16) are formed in the transition fluidized state hearth (102); an upper coal supply port (17) and an upper air supply port (18) are formed in the part, close to the transition fluidized state hearth (102), of the fast fluidized state hearth (103), a screen type heating surface (5) is installed in the fast fluidized state hearth (103), the outlet of the fast fluidized state hearth (103) is connected with a cyclone separator (6) through a horizontal flue, the upper outlet of the cyclone separator (6) is connected with a tail flue through a central cylinder (8), the lower outlet of the cyclone separator is connected with a discharging pipe (7), a material returning device (9) and an external heat exchanger (12) are arranged in a shunting manner on the discharging pipe (7), and a pipeline, connected with the discharging pipe (7), of the external heat exchanger (12) is an external heat exchanger feeding pipe (10); the external heat exchanger (12) is respectively provided with a first heat exchanger pipeline connected with the bubbling fluidized state hearth (101), a second heat exchanger pipeline connected with the transition fluidized state hearth (102), and a third heat exchanger pipeline connected with the fast fluidized state hearth (103), and the material returning device (9) is respectively provided with a first material returning pipeline connected with the first heat exchanger pipeline, a second material returning pipeline connected with the second heat exchanger pipeline, and a third material returning pipeline connected with the third heat exchanger pipeline.
2. The circulating fluidized bed/bubbling fluidized bed coupled pressurized oxycombustion apparatus of claim 1, wherein: the cross-sectional area of the bubbling fluidized-state furnace (101) is larger than that of the transition fluidized-state furnace (102) and the fast fluidized-state furnace (103).
3. The circulating fluidized bed/bubbling fluidized bed coupled pressurized oxycombustion apparatus of claim 1, wherein: the buried pipe heating surface (4) is a cold water buried pipe with high volume utilization rate.
4. The circulating fluidized bed/bubbling fluidized bed coupled pressurized oxycombustion apparatus of claim 1, wherein: the fuel feeding inlet of the pressurized hearth comprises a coal feeding port (14) arranged at the lower part of the bubbling fluidized hearth (101), a coal feeding port (15) arranged at the middle part of the transitional fluidized hearth (102) and a coal feeding port (17) arranged at the upper part of the fast fluidized hearth (103) in three stages along the height; coarse particles obtained after the fuel is screened are sent into a bubbling fluidized hearth (101) through a coal supply port (14) at the lower part of the bottom of the hearth; the fine fuel obtained by screening is sent into the hearth through a coal supply port (15) at the middle part of the hearth and a coal supply port (17) at the upper part of the hearth.
5. The circulating fluidized bed/bubbling fluidized bed coupled pressurized oxycombustion apparatus of claim 1, wherein: and the material returning device (9) and the external heat exchanger (12) respectively return solid materials to a bubbling fluidized hearth (101), a transitional fluidized hearth (102) and a fast fluidized hearth (103) of the hearths in three stages along the height of the hearths.
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