CN219120566U - Circulating fluidized bed boiler capable of burning sludge purely - Google Patents

Abstract

The utility model discloses a circulating fluidized bed boiler capable of burning sludge purely, which solves the problem of how to develop a circulating fluidized bed boiler which is suitable for burning sludge purely and can reach the emission standard of atmospheric pollutants. A stirring arm with a digging claw is arranged at the bottom of the desiccated sludge bin (1), a feeding hole (2) is arranged in a negative pressure zone (3) of a dense phase zone of the hearth, desiccated sludge (8) enters the hearth through the feeding hole, and a high-temperature overheat screen (11) is arranged in a dilute phase zone (10) of the hearth; the ratio of the diameter of the cylindrical barrel (14) to the diameter of the return pipe is 5-10; the ratio of the height of the cylindrical barrel (14) to the height of the conical transition barrel (15) is 0.3-1, and the height of the return pipe is 2-9 meters; a water-cooling evaporation tube bundle (20) is arranged in the first tail flue (19), and a high-temperature electric dust collector (24) is arranged in the second tail flue. The boiler can be ensured to stably and safely run for a long time.

Description

Circulating fluidized bed boiler capable of burning sludge purely

Technical Field

The utility model relates to a circulating fluidized bed boiler, in particular to a circulating fluidized bed boiler capable of burning sludge purely.

Background

Along with the development of economy, the amount of sludge generated in production and life is continuously increased, and the sludge treatment pressure is also increased; because the sludge contains pathogens, heavy metals, persistent organic matters and other toxic and harmful substances, if the treatment is not good, secondary pollution is easily caused to underground water, soil and the like; the sludge is dried and then burned, and the burned ash is utilized as a building material, so that an effective disposal scheme of the sludge is gradually formed; the sludge is dried and incinerated, so that the reduction, stabilization and innocuity of the sludge to a higher degree can be realized to the greatest extent, and the circulating fluidized bed boiler becomes available equipment for incinerating the sludge; however, the incineration treatment of sludge by using a circulating fluidized bed boiler has a great difficulty; because the sludge has the characteristics of low density, high water content, low heat value, high ash content and high heavy metal and chlorine content, when the sludge is combusted in the circulating fluidized bed boiler, the problems of hearth coking and slag bonding of a high-temperature heating surface are remarkable, so that the boiler cannot be stably combusted, and the continuous normal operation of the boiler is seriously influenced; the existing circulating fluidized bed boiler mainly comprises a hearth, a high-temperature cyclone separator and a tail flue, wherein the tail flue is sequentially provided with a high-temperature superheater, a low-temperature superheater, an economizer and an air preheater from top to bottom; because the water content in the sludge is high, the viscosity is also high, and the coking phenomenon is very easy to occur in the boiler combustion chamber due to poor fluidization.

The existing circulating fluidized bed boiler consists of a hearth, a cyclone separator and a tail flue, wherein the tail flue of the boiler is sequentially provided with the following parts from top to bottom: the flue gas enters the dust remover and the chimney through the outlet flue; when the boiler fuel is sludge, the heat value of the sludge is low, the density is low, the temperature of a hearth cannot be ensured, and the feeding of the boiler fuel into the boiler is difficult; the sludge ash content is larger, the alkali metal element content is high, alkali metal is easy to separate out on the tail high-temperature convection heating surface, and the heating surface is easy to pollute on the tail convection heating surface, so that the wall of the heating surface is corroded, the problem of bridging ash deposition on the tail heating surface is more serious due to the larger and thinner sludge ash, and particularly, the high-temperature superheater arranged in a tail flue accelerates alkali precipitation in ash on the outer wall of the pipe due to the high temperature in the pipe, so that the scaling phenomenon on the pipe wall is more serious.

The structure of the existing circulating fluidized bed boiler consists of a hearth, a high-temperature cyclone separator and a tail convection flue, wherein a superheater, an economizer and an air preheater are sequentially arranged in the tail convection flue from top to bottom, and flue gas finally enters a dust remover and a chimney through an outlet flue; because the water content in the sludge fuel is large, the blockage and the material breakage of the stokehold sludge feeding system are easy to occur, the density of the sludge is small, and the fuel is easy to reversely run into a stokehold sludge bin, so that accidents are caused; in addition, the sludge has high water content and high viscosity, is easy to agglomerate, and is extremely easy to agglomerate and coke in a combustion chamber; secondly, the sludge ash is larger, the chlorine element content is high, the tail convection heating surface is easy to pollute and corrode, deposit ash and the like, the safe and stable operation of the boiler is seriously affected, and the boiler cannot reach the standard stably in the aspect of atmospheric pollutant emission; the current technical route is basically as follows: the method has the advantages that the sludge with a certain proportion is mixed and burned in the fire coal, but the defect of small sludge treatment capacity exists, and how to develop a circulating fluidized bed boiler which is suitable for pure combustion of the sludge and can reach the emission standard of atmospheric pollutants becomes a problem to be solved on site urgently.

Disclosure of Invention

The utility model provides a circulating fluidized bed boiler capable of burning sludge purely, which solves the technical problem of how to develop a circulating fluidized bed boiler which is suitable for burning sludge purely and can stably run and reach the emission standard of atmospheric pollutants.

The utility model solves the technical problems by the following technical proposal:

the general conception of the utility model is that: the stokehold sludge bin of the circulating fluidized bed is a sludge silo with a material pressure relief system, a set of rotary discharging device is arranged at the bottom in the silo, two stirring arms made of special spring steel with excavating claws are used for stirring, the loosened and hardened sludge is uniformly conveyed to a discharging screw, and a sludge feeding point is arranged in a negative pressure area in a hearth; an adiabatic hearth is adopted, so that the temperature of the hearth is increased; optimizing the fluidization capacity of a dense phase zone at the lower part of a hearth of a traditional circulating fluidized bed boiler, and matching with a high-efficiency heat-insulation cyclone separator to achieve the purposes of stabilizing the stock of the hearth and improving the quality of the hearth; the proportion of coarse particles of fly ash in the hearth is reduced, the proportion of fine particles is increased, and a large amount of high-concentration circulating ash is formed in the hearth; the arrangement position of the high-temperature heating surface is optimized, the high-temperature superheater heating surface is arranged in the hearth in a screen mode, the alkali metal precipitation temperature interval is effectively avoided, the high-concentration circulating ash in the hearth is utilized for uninterrupted flushing, the surface cleaning of the high-temperature heating surface is ensured, and the occurrence of slag bonding and scale corrosion phenomena on the surface of the heating surface is avoided; arranging a traditional high-temperature superheater arranged in a tail flue to a dilute phase zone in a hearth, arranging three flues which are sequentially communicated end to end at the tail of a boiler, arranging a water-cooling evaporation tube bundle, a medium-temperature superheater, a low-temperature superheater and a high-temperature economizer in a first flue, arranging a high-temperature electric dust collector in a second flue, and arranging a denitration catalyst, a low-temperature economizer, a high-temperature air preheater and a low-temperature air preheater in a third flue; the flue gas in the hearth passes through a horizontal flue at the upper part of the hearth, firstly enters a water-cooling evaporation tube bundle, the temperature of the flue gas is reduced to below 650 ℃ after passing through the water-cooling evaporation tube bundle, then the temperature of the flue gas is designed to be below 400 ℃ through a low-temperature superheater arranged in a large-space sequence, the high-temperature corrosion activity temperature of a heating surface can be avoided to be greater than 500 ℃, a high-temperature economizer arranged in a large-space sequence is arranged below the low-temperature superheater, a second tail flue is arranged at the outlet of the high-temperature economizer, a high-temperature electric dust collector is arranged in the second tail flue, 90% of fly ash in the flue gas can be removed after passing through the high-temperature electric dust collector, and a third flue is arranged behind the second tail flue, so that the SCR catalyst of the third flue is not worn or blocked rapidly, and the emission of pollutants such as dioxin heavy metal is reduced in an auxiliary manner by using a fly ash injection bag type dust collector; thereby ensuring long-term safe use of the SCR catalyst, ensuring relatively clean flue gas after entering the low-temperature economizer with large spacing after passing through the SCR catalyst, and effectively preventing the heating surface from being polluted and corroded by being matched with proper soot blowing equipment; the low-temperature economizer is followed by an air preheater in a large-pitch in-line light pipe horizontal arrangement mode, and the heating surfaces arranged at large intervals can well avoid the phenomenon of bridging of the heating surfaces caused by dust accumulation.

The circulating fluidized bed boiler comprises a dried sludge bin, a circulating fluidized bed boiler heat-insulating hearth, a cyclone separator, a tail first flue, a tail second flue, a tail third flue, a bag type dust collector and a chimney, wherein a hearth dense-phase region negative pressure region and a hearth dilute-phase region are arranged in the circulating fluidized bed boiler heat-insulating hearth, the cyclone separator is connected to a smoke outlet of the circulating fluidized bed boiler heat-insulating hearth, the cyclone separator is communicated with the tail first flue through a horizontal flue, a tail second flue is connected to a smoke outlet of the tail first flue, a tail third flue is connected to a smoke outlet of the tail second flue, and a smoke outlet of the tail third flue is communicated with the chimney through the bag type dust collector; the cyclone separator is formed by sequentially connecting a cylindrical barrel, a conical transition barrel, a return pipe and a return box, wherein the return box is connected with a lower section of the return pipe, the lower end of the lower section of the return pipe is communicated with a return port on an adiabatic hearth of the circulating fluidized bed boiler, a stirring arm with a digging claw is arranged at the bottom of a drying sludge bin, a screw feeder is connected to a discharge port of the drying sludge bin, a blanking pipe is connected to the discharge port of the screw feeder, the other end of the blanking pipe is communicated with a feed port of the hearth, the feed port is arranged in a negative pressure zone of a dense-phase zone of the hearth, drying sludge enters the adiabatic hearth through the feed port, and a high-temperature overheat screen is arranged in a dilute-phase zone of the hearth; the ratio of the diameter of the cylindrical barrel to the diameter of the return pipe is 5-10; the ratio of the height of the cylindrical barrel to the height of the conical transition barrel is 0.3-1, and the height of the return pipe is 2-9 meters; a water-cooling evaporation tube bundle is arranged in the first flue at the tail part, and a high-temperature electric dust collector is arranged in the second flue at the tail part.

A primary air inlet and a secondary air inlet are respectively arranged on a hearth of the circulating fluidized bed boiler, and an air inlet hood for primary air inlet is arranged at the lower part of the heat-insulating hearth; the ratio of the primary air quantity entering the hearth through the primary air inlet to the secondary air quantity entering the hearth through the secondary air inlet is 45:55, and the air outlet speed of the air inlet hood is 37-38 meters per second; the cyclone separator conveys the high-temperature ash particles with the particle size of more than 20 mu m in the high-temperature ash particles back to the hearth through the lower section of the return pipe for circular combustion, and the cyclone separator conveys the high-temperature ash particles with the particle size of less than 20 mu m into the tail vertical shaft flue through the cylindrical barrel; the thickness of the bed material in the hearth is 400-520 mm; the flow rate of the flue gas in the adiabatic hearth of the circulating fluidized bed boiler is less than 4 meters per second, and the residence time of the flue gas in the adiabatic hearth is more than 5 seconds.

A water-cooling evaporation tube bundle, a medium-temperature superheater, a low-temperature superheater and a high-temperature economizer are sequentially arranged in the first tail flue from top to bottom, a high-temperature electric dust collector is arranged in the second tail flue, and a denitration catalyst, a low-temperature economizer, a high-temperature air preheater and a low-temperature air preheater are sequentially arranged in the third tail flue from top to bottom; the tail first flue soot blower is arranged in the tail first flue, and the tail third flue soot blower is arranged in the tail third flue.

The temperature of the flue gas discharged from the horizontal flue after passing through the water-cooling evaporation tube bundle is lower than 650 ℃, the temperature of steam in the medium-temperature superheater is lower than 400 ℃, and the tube of the low-temperature air preheater is a tube made of a enamel tube.

The utility model ensures that the sludge fuel is combusted in the furnace to release heat with high efficiency, simultaneously reduces the generation amount of dioxin pollutants in the furnace to the greatest extent, reduces the original generation amount of nitrogen oxides and sulfur dioxide from the source, and can greatly reduce the emission of atmospheric pollutants; and by adjusting the arrangement positions of the heating surfaces in the furnace, the corrosion area of the chlorides on the heating surfaces is skillfully avoided, so that the long-term stable and safe operation of the boiler is ensured.

Drawings

Fig. 1 is a schematic structural view of the present utility model.

Detailed Description

The utility model is described in detail below with reference to the attached drawing figures:

the circulating fluidized bed boiler of pure combustion mud, including drying the mud storehouse 1, circulating fluidized bed boiler adiabatic furnace, cyclone separator, afterbody first flue 19, afterbody second flue, afterbody third flue 25, bag dust collector 30 and chimney 31, in circulating fluidized bed boiler adiabatic furnace, there are dense-phase district negative pressure district 3 and furnace dilute-phase district 10 of the furnace, connect with cyclone separator on the exit flue 12 of the circulating fluidized bed boiler furnace, the cyclone separator is linked together with afterbody first flue 19 through horizontal flue 18, connect with afterbody second flue on the exit flue of afterbody first flue 19, connect with afterbody third flue 25 on the exit flue of afterbody second flue, the exit flue of afterbody third flue 25 is linked together with chimney 31 through the bag dust collector 30; the cyclone separator is formed by sequentially connecting a cylindrical barrel 14, a conical transition barrel 15, a return pipe and a return box 16, wherein the return box 16 is connected with a lower section 17 of the return pipe, the lower end of the lower section 17 of the return pipe is communicated with a return port 9 on a heat-insulating hearth of a circulating fluidized bed boiler, the bottom in a dried sludge bin 1 is provided with a stirring arm with a digging claw, the discharge port of the dried sludge bin 1 is connected with a screw feeder 32, the discharge port of the screw feeder 32 is connected with a blanking pipe 33, the other end of the blanking pipe 33 is communicated with a feed port 2 of the hearth, the feed port 2 is arranged in a dense-phase region negative pressure region 3 of the hearth, dried sludge 8 enters the hearth through the feed port 2, and a high-temperature overheat screen 11 is arranged in a dilute-phase region 10 of the hearth; the ratio of the diameter of the cylindrical barrel 14 to the diameter of the return pipe is 5-10; the ratio of the height of the cylindrical barrel 14 to the height of the conical transition barrel 15 is 0.3-1, and the height of the return pipe is 2-9 m; a water-cooling evaporation tube bundle 20 is arranged in the tail first flue 19, and a high-temperature electric dust collector 24 is arranged in the tail second flue; the boiler adopts a full heat insulation hearth, a low-temperature combustion technology, low flow rate in the hearth, high flow rate in the conical section of the hearth and good air distribution and air distribution plates, so that fluidization is uniform, and boiler coking and slagging are solved; the height of the hearth is improved, the residence time of the flue gas at high temperature is increased, the rigidity of secondary air is enhanced, substances which are not completely combusted in the flue gas are fully contacted with air, and the emission of dioxin is reduced; the high-efficiency adiabatic cyclone separator is adopted, and after the flue gas passes through the separator, the granularity of the fly ash in the flue gas is thinned, the amount of the fly ash is reduced, and the fly ash erosion abrasion and ash deposition of a heating surface in a tail flue are reduced; in addition, the high-efficiency separator ensures that the particle size of circulating materials in the hearth is finer, the quality of the bed is improved, and the flow state reconstruction is realized; after the bed quality is improved, the specific surface of limestone in the furnace is increased, and the desulfurization efficiency in the furnace is higher; after the bed quality is improved, the particle agglomeration capacity is enhanced, and the generation amount of NOx is inhibited; the middle-temperature screen type superheater and the high-temperature screen type superheater are arranged on the front wall of the hearth, and high-temperature corrosion is prevented by flushing a large amount of circulating materials in a main circulating loop of the circulating fluidized bed boiler; the temperature of the flue gas entering the low-temperature superheater is reduced through an evaporation tube bundle at the upper part of the tail flue, so that the metal wall temperature of the low-temperature superheater is ensured to be lower than a chloridizing corrosion active temperature range, and the corrosion probability of the low-temperature superheater is reduced; the tail heating surfaces are all arranged at large pitch, high flow speed and in sequence, and assist the steam soot blowers to prevent dust accumulation; the air preheaters are horizontally arranged by arranging light pipes in a large pitch in sequence, and adopt corrosion-resistant materials, so that the exhaust gas temperature is improved, and low-temperature corrosion is avoided.

In the hearth of the circulating fluidized bed boiler, a primary air inlet 4 and a secondary air inlet 13 are respectively arranged, an air inlet cap 6 of primary air is arranged in a water-cooled air chamber 5 at the lower part of the hearth, the ratio of the primary air quantity entering the hearth through the primary air inlet 4 to the secondary air quantity entering the hearth through the secondary air inlet 13 is 45:55, and the air outlet speed of the air inlet cap 6 is 37-38 meters per second; the cyclone separator conveys the high-temperature ash particles with the particle size of more than 20 mu m in the high-temperature ash particles back to the hearth through the lower section 17 of the return pipe for circular combustion, and the cyclone separator conveys the high-temperature ash particles with the particle size of less than 20 mu m into the tail shaft flue through the cylindrical cylinder (14); the thickness of the bed material 7 in the hearth is 400-520 mm; the outlet of the high-temperature economizer is provided with a high-temperature electric dust collector, 90% of fly ash in the flue gas can be removed after the flue gas passes through the high-temperature electric dust collector, and the subsequent SCR catalyst is not quickly worn or blocked by the fly ash, so that the safe use of the catalyst is ensured; the stable operation of the SCR selective catalyst further reduces the emission of NOx; and the flue gas entering the low-temperature economizer is relatively clean, soot blowing is properly carried out, and pollution and corrosion can be effectively prevented.

In the first tail flue 19, a water-cooling evaporation tube bundle 20, a medium-temperature superheater 21, a low-temperature superheater 22 and a high-temperature economizer 23 are sequentially arranged from top to bottom, a high-temperature electric dust collector 24 is arranged in the second tail flue, and in the third tail flue 25, a denitration catalyst 26, a low-temperature economizer 27, a high-temperature air preheater 28 and a low-temperature air preheater 29 are sequentially arranged from top to bottom; a tail first flue sootblower 34 is provided in the tail first flue 19 and a tail third flue sootblower 35 is provided in the tail third flue 25.

The temperature of the flue gas discharged from the horizontal flue 18 is lower than 650 ℃ after passing through the water-cooling evaporation tube bundles 20, the temperature of the steam in the medium-temperature superheater 21 is lower than 400 ℃, and the corrosion area of chlorides on the heating surfaces is skillfully avoided by adjusting the arrangement position of each heating surface in the boiler, so that the long-term stable and safe operation of the boiler is ensured; the low-temperature air preheater 29 is made of enamel pipe; dense pins are welded on a water cooling wall of a high temperature section in the fluidized bed combustion chamber, and wear-resistant plastic is coated on the dense pins so as to prolong the service life; the air distribution plate is a water-cooling air distribution plate, the hood is a bell-type hood, the primary air chamber is a water-cooling air chamber 5, and the slag discharging pipe is an alloy steel slag discharging pipe; the primary air chamber, the bell-type hood with low resistance and the alloy steel slag discharging pipe behind the boiler are horizontally arranged, so that the boiler is well fluidized and smooth in slag discharging during combustion.

The overall structural design of the circulating fluidized bed boiler for pure combustion of sludge ensures that proper circulating material quantity exists in a boiler hearth, so that the running bed temperature of the boiler, the hearth outlet smoke temperature, the separator returning temperature and the separator outlet temperature are all in the optimal reaction temperature, the temperature variation range is 50 ℃, and sulfides and nitrogen oxides actually generated by boiler combustion are greatly lower than those of the existing products; the utility model ensures that the secondary air port of the boiler furnace is burnt in a reducing atmosphere before being sprayed, the original concentration of sulfide and nitrogen oxide is removed through the cyclic adsorption of calcium spraying in the furnace and unreacted limestone in the materials, and the environment-friendly standard of the country can be achieved by matching with a semi-dry desulfurization device with lower cost, namely GB13223-2011 emission standard of atmospheric pollutants of thermal power plants and GB 13271 emission standard of atmospheric pollutants of boilers.

Claims (4)

1. The utility model provides a circulating fluidized bed boiler of pure combustion mud, including mummification mud storehouse (1), circulating fluidized bed boiler adiabatic furnace, cyclone, afterbody first flue (19), afterbody second flue, afterbody third flue (25), bag collector (30) and chimney (31), in circulating fluidized bed boiler adiabatic furnace, be provided with furnace dense phase district negative pressure district (3) and furnace dilute phase district (10), be connected with cyclone on circulating fluidized bed boiler adiabatic furnace's outlet flue (12), cyclone is in the same place with afterbody first flue (19) intercommunication through horizontal flue (18), be connected with afterbody second flue on the outlet flue of afterbody first flue (19), be connected with afterbody third flue (25) on the outlet flue of afterbody second flue, the outlet flue of afterbody third flue (25) is in the same place with chimney (31) intercommunication through bag collector (30); the cyclone separator is composed of a cylindrical barrel (14), a conical transition barrel (15), a return pipe and a return box (16) which are sequentially connected together, wherein the return box (16) is connected with a lower section (17) of the return pipe, the lower end of the lower section (17) of the return pipe is communicated with a return port (9) on a heat-insulating hearth of the circulating fluidized bed boiler, and the cyclone separator is characterized in that a stirring arm with a digging claw is arranged at the bottom of a drying sludge bin (1), a screw feeder (32) is connected to a discharge port of the drying sludge bin (1), a blanking pipe (33) is connected to a discharge port of the screw feeder (32), the other end of the blanking pipe (33) is communicated with a feed port (2) of the hearth, the feed port (2) is arranged in a negative pressure zone (3) of a dense phase zone of the hearth, drying sludge (8) enters the hearth through the feed port (2), and a high-temperature overheat screen (11) is arranged in a phase zone (10) of the hearth; the ratio of the diameter of the cylindrical barrel (14) to the diameter of the return pipe is 5-10; the ratio of the height of the cylindrical barrel (14) to the height of the conical transition barrel (15) is 0.3-1, and the height of the return pipe is 2-9 meters; a water-cooling evaporation tube bundle (20) is arranged in the first tail flue (19), and a high-temperature electric dust collector (24) is arranged in the second tail flue.

2. The circulating fluidized bed boiler of pure-combustion sludge according to claim 1, wherein a primary air inlet (4) and a secondary air inlet (13) are respectively arranged on a hearth of the circulating fluidized bed boiler, a water-cooling air chamber (5) is arranged at the lower part of the hearth, and an air inlet cap (6) of primary air is arranged in the water-cooling air chamber (5); the ratio of the primary air quantity entering the hearth through the primary air inlet (4) to the secondary air quantity entering the hearth through the secondary air inlet (13) is 45:55, and the air outlet speed of the air inlet hood (6) is 37-38 meters per second; the cyclone separator conveys high-temperature ash particles with the particle size of more than 20 mu m in the high-temperature ash particles back to a hearth through a lower section (17) of a return pipe for circular combustion, and the cyclone separator conveys the high-temperature ash particles with the particle size of less than 20 mu m into a tail shaft flue through a cylindrical cylinder (14); the thickness of the bed material (7) in the hearth is 400-520 mm, and the dried sludge (8) is arranged on the bed material (7) in the hearth; the flow rate of the flue gas in the adiabatic hearth of the circulating fluidized bed boiler is less than 4 meters per second, and the residence time of the flue gas in the adiabatic hearth is more than 5 seconds.

3. The circulating fluidized bed boiler of pure combustion sludge according to claim 2, characterized in that in the tail first flue (19) a water-cooled evaporating tube bundle (20), a medium-temperature superheater (21), a low-temperature superheater (22) and a high-temperature economizer (23) are arranged in sequence from top to bottom, in the tail second flue a high-temperature electric precipitator (24) is arranged, in the tail third flue (25) a denitration catalyst (26), a low-temperature economizer (27), a high-temperature air preheater (28) and a low-temperature air preheater (29) are arranged in sequence from top to bottom; a tail first flue soot blower (34) is arranged in the tail first flue (19), and a tail third flue soot blower (35) is arranged in the tail third flue (25).

4. A circulating fluidized bed boiler for pure combustion of sludge according to any of claims 1-3, characterized in that the flue gas discharged from the horizontal flue (18) is cooled by a water-cooled evaporating tube bundle (20) to a temperature below 650 ℃, the steam in the medium-temperature superheater (21) is cooled to a temperature below 400 ℃, and the tubes of the low-temperature air preheater (29) are tubes made of enamel tubes.

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