CN204328983U - A kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain - Google Patents

Abstract

The utility model discloses a CFB radiation hybrid boiler for reducing the pollution of high-alkaline coal, which comprises a fluidized bed furnace, a cyclone separator, a horizontal flue, a radiation boiler and a convective flue, and the fluidized bed furnace is connected with a cyclone separator. The cyclone separator is connected to the radiant boiler through the horizontal flue, and the bottom of the radiant boiler is connected to the horizontal convective flue; the radiant boiler is equipped with a radiant water-cooled wall and a radiant heat exchange screen, and the radiant water-cooled wall is a rectangular structure with a cavity. The heat exchange screen is located in the cavity; the radiation heat exchange screen includes multiple vertical plane radiation sub-screens, and each radiation sub-screen is formed by splicing a plurality of vertical risers, and the radiation sub-screen is radiated to the central axis of the water-cooled wall The center of the circle is arranged divergently; this utility model adopts the combination of the CFB boiler furnace and the radiation boiler, avoids the convective heat exchange surface in the range of 700°C-1100°C, and utilizes the circulation of coal ash to greatly reduce the pollution caused by the combustion of high-alkali metal coals question.

Description

A CFB Radiation Hybrid Boiler for Alleviating High Alkaline Coal Contamination

technical field

The utility model relates to the technical field of anti-pollution of high-alkaline coal, in particular to a CFB radiation hybrid boiler that reduces pollution of high-alkaline coal.

Background technique

my country's power generation industry is dominated by thermal power generation, with thermal power installed capacity exceeding 70%. Thermal power coal mostly uses low-quality and low-grade coal. Slagging of boiler furnace water wall and contamination of convective heating surface are one of the important problems that affect the normal operation of power plant boilers for a long time. Slagging and contamination will reduce the heat transfer efficiency of the boiler, affect the output of the boiler, and seriously reduce the operating safety of the equipment. Severe slagging and contamination may lead to major accidents such as boiler flameout, tube burst, and unplanned shutdown.

In order to prevent various problems caused by slagging and contamination, scholars at home and abroad have conducted a lot of research on the mechanism of slagging and contamination. Studies have shown that slagging and contamination are complex physical and chemical reaction processes, which are related to many factors such as coal characteristics, boiler design, and operating conditions, and multiple slagging and contamination judgment indexes have been proposed. However, since the combustion of coal in the boiler is an extremely complicated process, these slagging judgment indexes have great limitations in the actual application process. hazard problem.

The Zhundong coalfield is a super-large coalfield that has been discovered in Xinjiang in recent years. The estimated coal reserves are 390 billion tons. The coal is rich in alkali metal elements. High-temperature superheaters (high superheaters) and high-temperature reheaters appear in the combustion process of power plants. (High re)contamination and clogging, and other high-alkali metal coals will also have serious contamination during combustion.

Due to the volatilization of alkali metal elements during the combustion process of pulverized coal boilers, highly alkaline coal is easy to condense on the heating surface of the boiler to form a layer of bottoming deposits. The primer mainly exists in the form of NaCl or Na ₂ SO ₄ . After the above components volatilize at high temperature, they are easy to condense on the convective heating surface to form sintered or bonded ash deposits. With the adsorption of the attachment to the fly ash, it will The convection heating surface is contaminated to varying degrees, and it cannot be removed with a soot blower, resulting in a decrease in the heat transfer capacity of the heating surface, causing problems such as an increase in the exhaust gas temperature of the boiler, and finally greatly reducing the output of the furnace and causing the furnace to shut down.

Domestically, there is still a lack of experience in engineering operation for the use of burning high-alkaline coal. Only a few power plants in Xinjiang are studying the problem of high-alkaline coal combustion pollution. At present, there is no efficient way to use it. The pollution problem, the problem of blending coal with other coals is actually the addition of other low-alkaline metal coals, which reduces the relative content of alkali metals in raw coal. The proportion of high-alkaline coal blended in the boiler should not exceed 30%. When the proportion of blended combustion increases, the convective heating surface will be seriously contaminated and ash will form a flue gas corridor, and the flue gas will cause leakage of the high-temperature reheater and high-temperature superheater. Since high-alkaline coal is mostly used in pithead power stations in Xinjiang, the demand for coal blended with coal is large. This method is often limited by transportation conditions, which greatly increases operating costs.

For traditional power plant boilers, when burning high-alkaline coal, the alkali metal elements rich in coal are easy to deposit on the convective heating surface, so serious contamination occurs on the convective heating surface, resulting in boiler output Insufficient, the temperature of the tube wall is too high to cause the tube burst and so on. Studies have shown that the flue gas temperature in the range of 700°C-1100°C belongs to the area where pollution occurs seriously. Therefore, the contamination of highly alkaline coal is an urgent problem to be solved.

Utility model content

The utility model aims at the pollution problem caused by the burning of high-alkaline coal in traditional power station boilers, and proposes a CFB radiation hybrid boiler that reduces the pollution of high-alkaline coal. Based on the traditional CFB boiler furnace, its convective heating surface is cancelled. , arranging the downward radiation boiler and the horizontal convection heating section to generate superheated steam, through the circulation setting of the CFB boiler and the radiation boiler, the contamination of the heating surface is avoided, and the pure burning utilization of high-alkaline coal is realized.

The technical scheme of the utility model is as follows:

A CFB radiant hybrid boiler for reducing contamination of highly alkaline coal species, characterized in that it includes a fluidized bed furnace, a cyclone separator, a horizontal flue, a radiant boiler and a convective flue, and the fluidized bed furnace is connected to the cyclone separator , the cyclone separator is connected to the radiant boiler through the horizontal flue, and the bottom of the radiant boiler is connected to the horizontal convection flue; the radiant boiler is provided with a radiant water-cooled wall and a radiant heat exchange panel, and the radiant water-cooled wall is composed of multiple vertical The rectangular structure formed by the splicing of the risers, the rectangular structure is a cavity; the radiation heat exchange screen is located in the cavity of the radiation water wall, and the radiation heat exchange screen includes a plurality of vertical plane radiation sub-screens, each radiation sub-screen They are all formed by splicing a plurality of vertical risers, and the radiation sub-screens are divergently arranged with the central axis of the vertical direction of the radiation water-cooled wall as the center of the circle; every two adjacent risers of the radiation water-cooled wall and the radiation heat exchange screen are It is connected by welding.

The radiant boiler includes four side walls, a top wall and a funnel-shaped bottom wall, the side walls and the top wall are composed of an outer layer of refractory heat preservation material and an inner layer of membrane-type water wall, and the funnel-shaped bottom wall is a refractory material structure; Below the funnel-shaped bottom wall is a slag outlet, which forms the ash removal hopper in the radiation section; the slag outlet is made of refractory material.

The upper end of each riser of the radiant water wall and the radiant heat exchange panel communicates with the upper header, and the lower end of each riser communicates with the lower header.

The radiant water-cooled wall is also provided with a top-wall water-cooled wall on the top of the radiant boiler.

The descending radiant boiler replaces the original convection heating surface of the CFB combustion boiler. The special layout of the radiant heating surface of the radiant boiler reduces the erosion of the heating surface when the flue gas passes through, and because the flow velocity of the flue gas is small, it is not easy to deposit ash, which can reduce the occurrence of burning of high-alkaline coal. stained. At the bottom of the radiation heating section, the temperature of the flue gas drops below 700°C. At this time, the highly alkaline substances in the flue gas have condensed and deposited, and the flue gas is deflected laterally into the convection section, which greatly reduces the concentration of coal ash in the convection section. deposition.

The convection flue is horizontally arranged, connected with the radiation boiler, and equipped with convection heat transfer components. The convective heat transfer components include a secondary economizer, a primary economizer and an air preheater component; the convective heat transfer components are multiple groups of convective tube bundles, and the walls of the convective tube bundles are made of refractory and thermal insulation materials.

The back end of the convection flue is connected with a smoke exhaust flue; the flue gas passes through the second-level economizer, the first-level economizer and the air preheater for convective heat exchange, so that the outlet temperature of the flue gas can reach the specified standard.

The fluidized bed furnace is a conventional fluidized bed furnace with a water-cooled wall surface, a coal bunker is arranged on it, and a fluidization tuyere is arranged at the bottom of the fluidized bed furnace.

The working process of the present utility model is:

The high-alkaline coal powder and additives that have been pretreated by crushing and other pretreatments enter the fluidized bed furnace through the coal bunker, and after burning with the hot air heated by the air preheater from the fluidization tuyere, high-temperature flue gas is generated, and the high-temperature flue gas passes through The furnace outlet on the upper part of the fluidized bed furnace enters the cyclone separator, and most of the fly ash particles in the high-temperature flue gas are removed through the cyclone separator; the fly ash particles return to the fluidized bed furnace for recycling as combustion heat carriers; from the cyclone separator The high-temperature flue gas separated from the flue gas enters the downward radiant boiler through the horizontal flue. After the high-temperature flue gas exchanges heat with the radiant water-cooled wall panel and the radiant heat exchange panel in the radiant boiler, the temperature of the high-temperature flue gas will drop significantly. Usually, the high-temperature flue gas When the gas temperature drops to 700°C, the volume and flow velocity of the high-temperature flue gas will be greatly reduced, and the condensed ash particles will be obtained; the ash particles will settle in the slag outlet, and the flue gas will flow into the horizontal convection flue, After heat exchange through the secondary economizer, primary economizer and air preheater, it is discharged through the exhaust flue.

The utility model can also obtain the superheated steam required by the steam turbine for power generation through the heating surface and the flow path of water vapor. The specific water vapor flow is: the boiler feed water enters the first-level economizer, and the first-level economizer adopts countercurrent arrangement to obtain the maximum heat Utilization, the feed water enters the secondary economizer after being heated, the heated feed water is sent from the secondary economizer and enters the furnace water wall for heating, and the outlet steam of the furnace water wall is sent to the radiation heat exchange panel through steam-water separation. The superheated steam enters the steam turbine to generate electricity; the air can be preheated by the air preheater; the steam generated by the auxiliary steam generator can be used as desuperheating water to adjust the steam parameters at the outlet of the radiation heat exchange screen to avoid overheating of the tube wall temperature.

The boiler adopts the traditional CFB boiler furnace. After the pulverized coal enters the fluidized bed for combustion, the flue gas and coal ash enter the cyclone separator from the upper part of the fluidized bed furnace. After the separation of the cyclone separator, the coal ash enters the fluidized bed from the bottom. In the process, it is used as a heat carrier in a fluidized bed. Due to the mixing of coal ash, the relative content of alkali metal substances in the fluidized bed is effectively reduced, and the problem of burning contamination of the fluidized bed is avoided.

The beneficial effects of the utility model are as follows:

(1) The utility model provides a CFB-radiation hybrid boiler that reduces the pollution of high-alkaline coal types. It adopts the CFB boiler furnace and uses the circulation of coal ash to avoid the problem of combustion pollution in the fluidized bed.

(2) The utility model provides a CFB-radiation hybrid boiler that reduces the pollution of highly alkaline coal types. The CFB boiler furnace is used to cooperate with the downward radiation boiler to avoid convective heat transfer surfaces in the range of 700°C-1100°C. The pollution problem caused by the burning of high-alkali metal coal is greatly reduced.

(3) The utility model provides a CFB-radiation hybrid boiler that reduces the pollution of high-alkaline coal types. The flue gas at the outlet of the radiation boiler enters the convection section laterally. Cooling and deposition greatly reduce the degree of ash deposition in the convection section of the flue gas.

Description of drawings

Fig. 1 is the sectional structural representation of the utility model;

Fig. 2 is a schematic sectional view of A-A section in Fig. 1 of the present invention.

Among them, the reference signs are: 1 coal bunker, 2 fluidized bed furnace, 3 cyclone separator, 4 horizontal flue, 5 upper header, 6 top wall water wall, 7 radiant boiler, 8 radiant heat exchange screen, 9 radiant Water wall, 10 lower header, 11 slag outlet, 12 secondary economizer, 13 primary economizer, 14 air preheater, 15 fluidizing tuyere, 16 convection flue, 17 side wall, 18 top wall , 19 funnel-shaped bottom walls.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the utility model is described in further detail:

As shown in Figure 1-2, a CFB radiant hybrid boiler that reduces contamination from highly alkaline coals includes a fluidized bed furnace 2, a cyclone separator 3, a horizontal flue 4, a radiant boiler 7, and a convection flue 16 , the fluidized bed furnace 2 is connected to the cyclone separator 3, the cyclone separator 3 is connected to the radiant boiler 7 through the horizontal flue 4, and the bottom of the radiant boiler 7 is connected to the horizontal convection flue 16; the radiant boiler 7 is provided with a radiant water-cooled wall 9 and a radiation heat exchange screen 8, the radiation water cooling wall 9 is a rectangular structure formed by splicing a plurality of vertical risers, and the inside of the rectangular structure is a cavity; In the cavity, the radiation heat exchange screen 8 includes a plurality of vertical plane radiation sub-screens, and each radiation sub-screen is formed by splicing a plurality of vertical risers. The center of the circle is arranged divergently; every two adjacent risers of the radiant water cooling wall 9 and the radiant heat exchange panel 8 are connected by welding.

The radiant boiler 7 includes four side walls 17, a top wall 18 and a funnel-shaped bottom wall 19. The side walls 17 and the top wall 18 are composed of an outer layer of refractory insulation material and an inner layer of membrane-type water-cooled wall. The funnel-shaped bottom The wall 19 is made of refractory material; the bottom of the funnel-shaped bottom wall 19 is a slag outlet 11, forming a radiant section ash removal bucket; the slag outlet 11 is made of a refractory material.

The upper end of each standpipe of the radiation water cooling wall 9 and the radiation heat exchange panel 8 communicates with the upper header 5 , and the lower end of each standpipe communicates with the lower header 10 .

The radiant water-cooled wall 9 is also provided with a top-wall water-cooled wall 6 at the top of the radiant boiler 7 .

The descending radiant boiler 7 replaces the original convection heating surface of the CFB combustion boiler. The special arrangement of the radiant heating surface of the radiant boiler 7 reduces the erosion of the heating surface when the flue gas passes through, and because the flow velocity of the flue gas is small, it is not easy to deposit ash, which can reduce the occurrence of high-alkaline coal. contamination. At the bottom of the radiation heating section, the temperature of the flue gas drops below 700°C. At this time, the highly alkaline substances in the flue gas have condensed and deposited, and the flue gas is deflected laterally into the convection section, which greatly reduces the concentration of coal ash in the convection section. deposition.

The convection flue 16 is arranged laterally and horizontally, is connected with the radiation boiler 7, and is provided with convective heat transfer components. The convective heat transfer components include a secondary economizer 12, a primary economizer 13 and an air preheater 14; the convective heat transfer components are multiple groups of convective tube bundles, and the walls of the convective tube bundles are made of refractory and thermal insulation materials.

The back end of the convection flue 16 is connected with a smoke exhaust flue; the flue gas passes through the secondary economizer 12, the primary economizer 13 and the air preheater 14 for convective heat exchange, so that the outlet temperature of the flue gas can reach the specified standard.

The fluidized bed furnace 2 is a conventional fluidized bed furnace 2 with a water-cooled wall surface, on which a coal bunker 1 is arranged, and a fluidization tuyere 15 is arranged at the bottom of the fluidized bed furnace 2 .

The working process of the present utility model is:

The high-alkaline coal powder and additives that have been pretreated by crushing etc. enter the fluidized bed furnace 2 through the coal bunker 1, and after burning with the hot air heated by the air preheater 14 from the fluidization tuyere 15, high-temperature flue gas is generated. The high-temperature flue gas enters the cyclone separator 3 through the upper furnace outlet of the fluidized bed furnace 2, and most of the fly ash particles in the high-temperature flue gas are removed through the cyclone separator 3; the fly ash particles return to the fluidized bed furnace as combustion heat carrier 2 recycling; the high-temperature flue gas separated from the cyclone separator 3 enters the downward radiant boiler 7 through the horizontal flue 4, and the high-temperature flue gas exchanges heat with the radiant water-cooled wall 9 screen and the radiant heat exchange screen 8 in the radiant boiler 7 After that, the temperature of the high-temperature flue gas will drop significantly, usually the temperature of the high-temperature flue gas will drop to 700°C, the volume and flow rate of the high-temperature flue gas will be greatly reduced, and the condensed ash particles will be obtained; the ash particles will settle at the slag outlet 11, and the flue gas deflects into the horizontal convection flue 16, passes through the secondary economizer 12, the primary economizer 13 and the air preheater 14 for heat exchange, and is discharged through the exhaust flue.

The utility model can also obtain the superheated steam required by the steam turbine for power generation through the heating surface and the flow path of water vapor. The specific water vapor process is as follows: boiler feed water enters the primary economizer 13, and the primary economizer 13 adopts countercurrent arrangement to obtain Maximum heat utilization, the feed water enters the secondary economizer 12 after being heated, the heated feed water is sent out from the secondary economizer 12 and enters the furnace water wall for heating, and the outlet steam of the furnace water wall is sent into the qualified steam obtained by steam-water separation The radiation heat exchange screen 8 is overheated, and the superheated steam enters the steam turbine to generate electricity; the air can be preheated by the air preheater 14; the steam generated by the auxiliary steam generator can be used as desuperheating water to adjust the steam parameters at the outlet of the radiation heat exchange screen 8 Avoid pipe wall temperature overheating.

The boiler adopts a traditional CFB boiler furnace. After the pulverized coal enters the fluidized bed for combustion, the flue gas and coal ash enter the cyclone separator 3 from the upper part of the fluidized bed furnace 2. After the separation of the cyclone separator 3, the coal ash enters from the bottom. In the fluidized bed, it is used as the heat carrier of the fluidized bed. Due to the mixing of coal ash, the relative content of alkali metal substances in the fluidized bed is effectively reduced, and the problem of burning contamination of the fluidized bed is avoided.

The high-temperature flue gas comes out from the upper part of the cyclone separator 3, and the horizontal flue 4 is arranged as short as possible according to actual needs, and the flue gas is introduced into the downward radiant boiler 7 to replace the original convection heating surface to generate superheated steam. The walls of the radiant boiler 7 adopt a membrane wall structure, including side walls 17 and top walls 18 , and radiation heat exchange panels 8 are arranged in the side walls 17 . When the flue gas enters the downward radiant boiler 7, due to the large cross-sectional area of the radiant boiler 7, its downward speed is extremely slow, the flue gas is in a laminar flow state, and its radiative heat exchange can be fully carried out. A small protective clip is arranged at the entrance of the radiant boiler 7 Cover and guide the flue gas, so that the flue gas does not contact or less contact with the wall during the slow descent. The arrangement of the height of the radiant boiler 7 needs to meet: (1) The superheated steam in the heating surface of the radiant boiler 7 must meet the requirements of the steam turbine inlet; (2) The temperature of the flue gas is lowered to below 700°C, which can ensure that the boiler burns high-alkali metal coal. No staining occurs when heated.

An economizer, an air preheater 14, etc. are arranged horizontally at the outlet of the radiant boiler 7. The temperature of the flue gas at the bottom of the radiant section has dropped below 700°C, and the highly alkaline substances in the flue gas are deposited at the bottom of the radiant section at a slow air velocity. Then the flue gas changes flow direction and enters the convection section laterally, which will greatly reduce the degree of ash deposition in the economizer and air preheater 14 in the convection section.

Claims (8)

1. the CFB radiation mixed type boiler alleviating high alkalinity coal and stain, it is characterized in that: comprise fluid bed burner hearth (2), cyclone separator (3), horizontal flue (4), radiant boiler (7) and convection pass (16), fluid bed burner hearth (2) connects cyclone separator (3), cyclone separator (3) connects radiant boiler (7) by horizontal flue (4), and the bottom of radiant boiler (7) connects the convection pass (16) of level; Be provided with radiation water-cooling wall (9) and radiation heat transfer screen (8) in described radiant boiler (7), described radiation water-cooling wall (9) is the rectangle structure be spliced to form by multiple vertical standpipe, is cavity in rectangle structure; Described radiation heat transfer screen (8) is positioned at the cavity of radiation water-cooling wall (9), radiation heat transfer screen (8) comprises multiple perpendicular radiator screen, each radiator screen is all be spliced to form by multiple vertical standpipe, and radiator screen is that layout is dispersed in the center of circle with the central axis of radiation water-cooling wall (9) vertical direction; Described radiation water-cooling wall (9) is all be connected by welding manner with often adjacent two standpipes of radiation heat transfer screen (8).

2. a kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain according to claim 1, it is characterized in that: described radiant boiler (7) comprises four sidewalls (17), a roof (18) and funnel type diapire (19), sidewall (17), roof (18) all have and are made up of outer flame-proof thermal insulation material and internal layer fin panel casing, and funnel type diapire (19) is structure of refractory.

3. a kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain according to claim 2, is characterized in that: the below of described funnel type diapire (19) is slag notch (11), forms radiant section except ash bucket; Described slag notch (11) is structure of refractory.

4. a kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain according to claim 1, it is characterized in that: radiation water-cooling wall (9) is all communicated with upper collecting chamber (5) with the upper end of each standpipe of radiation heat transfer screen (8), and the lower end of each standpipe is communicated with lower header (10).

5. a kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain according to claim 4, is characterized in that: radiation water-cooling wall (9) is also provided with roof water-cooling wall (6) at radiant boiler (7) inner top.

6. a kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain according to claim 1, it is characterized in that: described convection pass is provided with convection heat transfer' heat-transfer by convection parts in (16), convection heat transfer' heat-transfer by convection parts comprise secondary economizer (12), one-level economizer (13) and air preheater (14) parts that transverse horizontal is successively installed; Convection heat transfer' heat-transfer by convection parts for organize convection bank more, and the wall of convection bank is flame-proof thermal insulation material.

7. a kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain according to claim 6, is characterized in that: the rear end of convection pass (16) is connected with exit flue.

8. a kind of CFB radiation mixed type boiler alleviating high alkalinity coal and stain according to claim 1, it is characterized in that: described fluid bed burner hearth (2) is the fluid bed burner hearth (2) of band wall-cooling surface, the upper end, side of fluid bed burner hearth (2) is provided with coal bunker (1), and the bottom of fluid bed burner hearth (2) is provided with fluidisation air port (15).