EP0431163A1 - Chaudiere a lit fluidise a circulation composite - Google Patents

Chaudiere a lit fluidise a circulation composite Download PDF

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Publication number
EP0431163A1
EP0431163A1 EP89909857A EP89909857A EP0431163A1 EP 0431163 A1 EP0431163 A1 EP 0431163A1 EP 89909857 A EP89909857 A EP 89909857A EP 89909857 A EP89909857 A EP 89909857A EP 0431163 A1 EP0431163 A1 EP 0431163A1
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EP
European Patent Office
Prior art keywords
fluidized bed
chamber
combustion chamber
air
thermal energy
Prior art date
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Application number
EP89909857A
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German (de)
English (en)
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EP0431163A4 (en
EP0431163B1 (fr
Inventor
Takahiro Ohshita
Shuichi Nagato
Norihisa Miyoshi
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Ebara Corp
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Ebara Corp
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Publication of EP0431163A4 publication Critical patent/EP0431163A4/en
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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
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
    • F22B31/0007—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed
    • F22B31/0084—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed with recirculation of separated solids or with cooling of the bed particles outside the combustion bed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
    • F22B31/0007—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed
    • F22B31/0084—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed with recirculation of separated solids or with cooling of the bed particles outside the combustion bed
    • F22B31/0092—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus with combustion in a fluidized bed with recirculation of separated solids or with cooling of the bed particles outside the combustion bed with a fluidized heat exchange bed and a fluidized combustion bed separated by a partition, the bed particles circulating around or through that partition

Definitions

  • the present invention relates to an internal recycling type fluidized bed boiler in which combustion materials such as various coals, low grade coal, dressing sludge, oil cokes and the like are burnt by a so-called whirling-flow fluidized bed and which recovers thermal energy from a recycling fluidized bed, the interior of a free board and a heat transfer portion provided downstream of the free board portion.
  • combustion materials such as various coals, low grade coal, dressing sludge, oil cokes and the like are burnt by a so-called whirling-flow fluidized bed and which recovers thermal energy from a recycling fluidized bed, the interior of a free board and a heat transfer portion provided downstream of the free board portion.
  • a fluidized bed boiler is classified into two types as noted below according to the difference in a system wherein arrangement of heat transfer portions and combustion of unburnt particles flown out from the fluidized bed are taken into account.
  • a heat transfer tube is arranged within a fluidized bed, and heat exchange is carried out by physical contact between the burning fuel and a fluidizing medium with high heat transfer efficiency.
  • fine unburnt materials, ash and/or a part of the fluidizing medium (recycling solid) are merged into a flow of combustion gas and guided to a heat exchanging portion arranged independently of the combustion chamber where combustion of the unburnt particles is continued and the circulating solid having been heat exchanged is returned to the combustion chamber, the aforesaid title being named since the solid is recycled.
  • Fig. 4 shows a non-recycling type fluidized bed boiler, in which air for fluidization fed under pressure from a blower not shown is injected from an air chamber 74 into a boiler 71 through a diffusion plate 72 to form a fluidized bed 73, and fuel, for example, granular coal is supplied to the fluidized bed 73 for combustion.
  • Heat transfer tubes 76 and 77 are provided in the fluidized bed 73 and an exhaust gas outlet of a free board portion, respectively, to recover thermal energy.
  • Exhaust gas cooled to a relatively low temperature is guided from an exhaust gas outlet of the free board portion to a convection heat transfer portion 78 to recover thermal energy and discharged outside the system after contained particles are recovered at a cyclone 79.
  • Ash recovered in the convection heat transfer portion is taken out through a tube 81 and discharged outside the system via a tube 82 together with ash taken out from a tube 80, a part thereof being returned to the fluidized bed 73 for re-burning through the air chamber 74 or a fuel inlet 75.
  • Fig. 5 shows a recycling type fluidized bed boiler, in which air for fluidization fed under pressure from a blower not shown is blown from an air chamber 104 into a furnace 101 through a diffusion plate 102 to fluidize and burn granular coal containing lime as a desulfurizing agent to be supplied into the furnace as needed.
  • injecting speed of fluidizing air blown through the diffusion plate 102 is higher than the terminal speed of the fluidizing particles, and therefore, mixing of particles and gas is more actively effected and the particles are blown upward together with gas so that a fluidizing layer and a jet-stream layer are formed in that order from the bottom over the whole zone of the combustion furnace.
  • the particles and gas are guided to a cyclone 108 after a small amount of heat exchange is effected at a water cooling furnace wall 107 provided halfway.
  • the combustion gas passed through the cyclone 108 is heat exchanged at a convection heat transfer portion 109 arranged in a flue at the rear portion.
  • the particles collected at the cyclone 108 are again returned to the combustion chamber via a flowpassage 113, and a part of the particles is guided to an external heat exchanger 115 via a flowpassage 114 for the purpose of controlling the furnace temperature and after being cooled, it is again returned to the combustion chamber while partly discharged outside the system as ash.
  • a feature lies in that the particles are recycled into the combustion chamber in a manner as just mentioned.
  • the recycling particles are mainly limestone supplied as a desulfurizing agent, burnt ash of supplied coal and unburnt ash, etc.
  • a thermal energy recovery portion such as a vaporizing tube is provided in a free board portion above the fluidized bed or in a portion downstream of the free board portion and exhaust gas is, after being cooled to a low temperature by heat exchange, directed to a cyclone and particles collected at the cyclone are returned to a descending moving bed of the fluidizing medium in the fluidized bed.
  • the inventors further found that selection of coal is not limited to a certain kind because even coal of a high fuel ratio may be completely burnt by the whirling flow, and silica sand can be used as a fluidizing medium together with limestone for reducing SOx whereby all the problems encountered in the conventional coal boilers can be solved.
  • an internal recycling type fluidized bed boiler in which a fluidized bed is generally partitioned into a primary combustion chamber and a thermal energy recovery chamber, the primary combustion chamber being accompanied by at least two kinds of air chambers disposed below the primary chambers, i.e., an air chamber for imparting a high fluidizing speed and an air chamber for imparting a low fluidizing speed, these different fluidizing speeds being combined to thereby impart a whirling flow to a fluidizing medium within the primary combustion chamber to form a thermal energy recovery recycling flow of fluidizing medium between the primary combustion chamber and the thermal energy recovery chamber.
  • exhaust gas is guided into a cyclone and collected particles at the cyclone are returned to a descending moving bed of the primary combustion chamber or the thermal energy recovery chamber.
  • the collected particles are not always from the cyclone but collected particles from a bag filter or the like can also be returned to the descending moving bed. Returning of collected particles into the descending moving bed causes unburnt composition (char) of the collected particles to be evenly scattered within the fluidized bed so that the whole portion in the bed becomes a reduced atmosphere thereby reducing NOx in a zone ranging from the fluidized bed to the free board portion.
  • the char is participated in any of reactions above. It is considered that the oxidization reactivity and catalyst effect of char exert an influence on the function of reducing the generation of NOx.
  • heat transfer tubes are arranged in a free board portion above a fluidized bed or downstream of the free board portion, and recovery of thermal energy is primarily effected by convection heat transfer.
  • a convection heat transfer portion has been provided independently of a free board portion.
  • a convection heat transfer portion is provided unitarily with a free board portion at an upper part within a free board or downstream of a free board portion while sufficient volume required for secondary combustion in a free board portion is retained.
  • treatment of dust and recycling of char around a boiler can be facilitated as compared to the prior art.
  • the temperature of gas entering into a cyclone becomes 250 to 400°C, and therefore, the cyclone need not be provided with castable lining, and the cyclone can be made of steel and be light in weight and miniaturized.
  • a convection heat transfer portion is provided at an upper part within a free board or a furnace wall is constructed to comprise water cooling tubes.
  • heat insulating material such as refractory material is lined on the convection heat transfer portion and the water cooling furnace wall on the side of the combustion chamber in order to prevent the temperature of the combustion gas within the free board from being lowered due to radiation effect.
  • refractory heat insulating material may be lined only on a water cooling wall constituting the free board portion.
  • the present invention provides a composite recycling type fluidized bed boiler effecting a combination of three circulative movements, i.e., a whirling flow circulation in the primary combustion chamber, a thermal energy recovering circulative movement of a fluidizing medium recycled between a primary combustion chamber and a thermal energy recovery chamber, and an external recycling (char recycling) for returning unburnt char to a descending moving bed of a fluidizing medium within a primary combustion chamber or a thermal energy recovery chamber.
  • three circulative movements i.e., a whirling flow circulation in the primary combustion chamber, a thermal energy recovering circulative movement of a fluidizing medium recycled between a primary combustion chamber and a thermal energy recovery chamber, and an external recycling (char recycling) for returning unburnt char to a descending moving bed of a fluidizing medium within a primary combustion chamber or a thermal energy recovery chamber.
  • Figs. 1, 2 and 3 are schematic views of different types of composite recycling type fluidized bed boilers, respectively, according to the present invention, in which heat transfer tubes such as vaporization tubes are disposed at an upper part within a free board;
  • Fig. 4 is a schematic view of a conventional fluidized bed boiler;
  • Fig. 5 is a schematic view of a conventional recycling type fluidized bed boiler;
  • Fig. 6 is a graph indicating the relationship between an amount of fluidizing air at a lower portion of an inclined partition wall and a recycling amount of a fluidizing medium in a thermal energy recovery chamber;
  • Fig. 7 is a graph indicating the relationship between an amount of diffusing air for a thermal energy recovery chamber and a descending rate of downwardly moving bed;
  • Fig. 1 is a schematic view of different types of composite recycling type fluidized bed boilers, respectively, according to the present invention, in which heat transfer tubes such as vaporization tubes are disposed at an upper part within a free board;
  • Fig. 4 is a schematic
  • Fig. 8 is a graph generally indicating a mass flow for fluidization and an overall thermal conducting coefficient
  • Fig. 9 is a graph indicating an amount of diffusing air for a thermal energy recovery chamber and an overall thermal conducting coefficient in an internal recycling type
  • Fig. 10 is a graph indicating the relationship between a fluidizing mass flow and an abrasion rate of a heat transfer tube
  • Fig. 11 is a schematic view of a composite recycling type fluidized bed boiler according to the present invention in which a group of heat transfer tubes such as vaporization tubes integrally provided with a free board portion are arranged downstream of the free board portion
  • Fig. 12 is a sectional view taken along the line A - A of Fig. 11; Fig.
  • FIG. 13 is a sectional view along a sectioning line corresponding to the line A - A of Fig. 11 in a composite recycling type fluidized bed boiler designed so that a group of heat transfer tubes such as vaporization tubes integrally provided with a free board portion are disposed downstream of the free board portion and relatively large particles collected at said group of heat transfer tubes are returned to left and right thermal energy recovery chambers disposed on opposite sides of a primary combustion chamber; and
  • Fig. 14 is a view showing an embodiment in which particles containing fine char collected at a cyclone are returned to a carrier such as a conveyor for returning particles collected at said group of heat transfer tubes to the fluidized bed portion.
  • a boiler body 1 is internally provided on the bottom thereof with a diffusion plate 2 for an fluidizing air which is introduced from a fluidizing air introducing tube 15 by means of a blower 16, the diffusion plate 2 having opposite edges arranged to be higher than a central portion of the plate, the bottom of the boiler body being formed as a concave surface.
  • the fluidizing air fed by the blower 16 is injected upwardly from the air diffusion plate 2 via air chambers 12, 13 and 14.
  • a mass flow of the fluidizing air injected out of the central air chamber 13 is arranged to be enough to form a fluidized bed of a fluidizing medium within the boiler body, that is, in the range of 4 to 20 Gmf, preferably, in the range of 6 to 12 Gmf.
  • a mass flow of the fluidizing air injected out of the air chambers 12 and 14 on the opposite sides is smaller than the former, generally, in the range of 0 to 3 Gmf.
  • air is injected in a mass flow of 0 to 2 Gmf from the air chamber 12 located below the thermal energy recovery chamber 4 and provided with a heat transfer tube 5, and air is injected in a mass flow of 0.5 to 2 Gmf from the air chamber 14 which forms a lower portion of the primary combustion chamber 3.
  • the mass flow of the fluidizing air injected out of the air chamber 13 within the primary combustion chamber 3 is relatively larger than that of the fluidizing air injected out of the air chambers 12 and 14, the air and the fluidizing medium are rapidly moved upward in the portion above the air chamber 13 forming a jet stream within the fluidized bed, and upon passing through the surface of the fluidized bed, they are diffused and the fluidizing medium falls onto the surface of the fluidized bed at the portions above the air chambers 12 and 14.
  • fluidizing medium under gentle fluidization at the opposite sides moves to occupy a space from where the fluidizing medium is moved upward.
  • the fluidizing medium in the fluidized bed above the air chambers 12 and 14 is moved to the central portion, i.e., the portion above the air chamber 13.
  • a violent upward stream is formed in the central portion in the fluidized bed but a gentle descending moving bed is formed in the peripheral portions.
  • the thermal energy recovery chamber 4 makes use of the aforesaid descending moving bed.
  • Fig. 8 shows the relationship between an overall thermal conducting coefficient and a fluidizing mass flow in a bubbling system.
  • a large overall thermal conducting coefficient is obtained at a fluidizing mass flow of 1 to 2 Gmf as shown in Fig. 7 without effecting such severe fluidization (generally, 3 to 5 Gmf) as in the bubbling system and sufficient thermal energy recovery can be effected.
  • a vertical partition wall 18 is provided internally of the fluidized bed at the portion above a boundary between the air chambers 12 and 13, and the heat transfer tube 5 is arranged at the portion above the air chamber 12 to form a thermal energy recovery chamber, that is, internally of the fluidized bed between the back of the partition wall 18 and the water cooling furnace wall.
  • the height of the partition wall 18 is designed to be sufficient for allowing the fluidizing medium to pass from a portion above the air chamber 13 into the thermal energy recovery chamber 4 during operation, and an opening 19 is provided between the partition wall 18 and the air diffusion plate on the bottom so that the fluidizing medium within the thermal energy recovery chamber 4 may be returned into the primary combustion chamber 3.
  • the fluidizing medium diffused above the surface of the fluidized bed after having been violently moved up as a jet stream within the primary combustion chamber moves beyond the partition wall 18 into the thermal energy recovery chamber, and is gradually moved down while being gently fluidized by air blown from the air chamber 12 with heat exchange being effected through the heat transfer tube 5 during its descent.
  • the recycling amount of the descending fluidizing medium in the thermal energy recovery chamber is dependent on the amount of diffusing air fed from the air chamber 12 to the thermal energy recovery chamber 4 and the amount of fluidizing air fed from the air chamber 13 in the primary combustion chamber. That is, as shown in Fig. 6, the amount G1 of the fluidizing medium entering into the thermal energy recovery chamber 4 increases as the amount of the fluidizing air blown out of the air chamber 13 increases. Also, as shown in Fig. 7, when the amount of diffusing air fed into the thermal energy recovery chamber 4 is varied in the range of 0 to 1 Gmf, the amount of the fluidizing medium descending in the thermal energy recovery chamber substantially varies proportionally thereto, and is substantially constant if the amount of diffusing air in the thermal energy recovery chamber exceeds 1 Gmf.
  • the aforesaid constant amount of the fluidizing medium is substantially equal to the fluidizing medium amount G1 moved into the thermal energy recovery chamber 4, and the amount of fluidizing medium descending in the thermal energy recovery chamber corresponds to G1. With these two amounts of air being regulated, the descending rate of the fluidizing medium in the thermal energy recovery chamber 4 is controlled.
  • thermal energy is recovered from the descending fluidizing medium through the heat transfer tube 5.
  • the heat conducting coefficient changes substantially linearly as shown in Fig. 9 when the diffusing amount of air fed into the thermal energy recovery chamber 4 from the air chamber 12 is changed from 0 to 2 Gmf, and therefore, the thermal energy recovery amount and the fluidized bed temperature within the primary combustion chamber 3 can be optionally controlled by regulating the amount of diffusing air.
  • the fluidizing medium recycling amount increases when the amount of diffusing air within the thermal energy recovery chamber 4 is increased and at the same time the thermal conducting coefficient is increased, whereby the amount of thermal energy recovery is considerably increased as a result of synergistic effect. If an increment of the aforesaid amount of thermal energy recovery is balanced with an increment of the generated thermal energy in the primary combustion chamber, the temperature of the fluidized bed is maintained at constant.
  • an abrasion rate of a heat transfer tube in a fluidized bed is proportional to the cube of a fluidizing flow rate.
  • Fig. 10 shows the relationship between a fluidizing mass flow and an abrasion rate. That is, with the amount of diffusing air blown into the thermal energy recovery chamber being kept at 0 to 3 Gmf, preferably, 0 to 2 Gmf, the heat transfer tube encounters an extremely small degree of abrasion and thus durability can be enhanced.
  • coal as fuel is supplied to the initiating portion of the descending moving bed within the primary combustion chamber 3. Therefore, coal supplied as above is whirled and circulated within the high temperature fluidized bed, and even coal of a high fuel ratio can be completely burnt. Since high load combustion is made available, a boiler can be miniaturized, and in addition, there is no restriction on the kind of coals which may be selected so that the use of boilers is promoted.
  • Exhaust gas is discharged from the boiler and guided to the cyclone 7.
  • particles collected at the cyclone pass through a double damper 8 disposed at a lower portion in the boiler shown in Fig. 1 and are introduced into a hopper 10 together with coal simultaneously supplied, with the both being mixed by a screw feeder 11 and fed to the descending moving bed of the primary combustion chamber thereby contributing to the incineration of unburnt substance (char) in the collected particles and to the reduction of NOx.
  • particles collected at the cyclone will, of course, be mixed with coal due to whirling and circulation in the primary combustion chamber even if they are not preliminarily mixed in advance with the particles and coal being independently transported to a portion before the primary combustion chamber and fed into the descending moving bed of the primary combustion chamber.
  • a convection heat transfer surface means 6 is provided to effect heat recovery as an economizer and a vaporizing tube.
  • a heat insulating material 17 such as a refractory material is mounted as required on the lower portion of the convection heat transfer surface means 6 and the water cooling furnace wall on the side of the combustion chamber in order to maintain the combustion temperature in the free board at a constant temperature, preferably, 900°C.
  • each heat transfer tube near the free board portion is mounted so as to be wound with a heat insulating material. Needless to say, a pitch of the heat transfer tube is taken into consideration so as not to impede a flow passage of the exhaust gas.
  • Fig. 2 shows a further embodiment of the present invention.
  • this embodiment is similar, with respect to its construction, to the boiler shown in Fig. 1 and performs an operation similar thereto.
  • a lower portion of a partition wall 38 between a primary combustion chamber 23 and a thermal energy recovery chamber 24 is inclined so as to interrupt, in the primary combustion chamber, an upward flow from an air chamber 33 under a high fluidizing rate and to turn the flow toward an air chamber 34 under a low fluidizing rate, the angle of inclination being 10 to 60 degrees relative to the horizon, preferably 25 to 45 degrees.
  • the horizontal length l of the inclined portion of the partition wall projected onto the furnace bottom is arranged to be 1/6 to 1/2, preferably 1/4 to 1/2 of the horizontal length L of the opposing furnace bottom.
  • the fluidized bed at the bottom of a boiler body 21 is divided by the partition wall 38 into the thermal energy recovery chamber 24 and the primary combustion chamber 23, and an air diffusion plate 22 for fluidization is provided at the bottom of the primary combustion chamber 23.
  • the central portion of the diffusion plate 22 is arranged to be low and the side opposite the thermal energy recovery chamber to be high.
  • Two kinds of air chambers 33 and 34 are provided below the diffusion plate 22.
  • a mass flow of fluidizing air injected out of the central air chamber 33 is arranged to be enough for causing a fluidizing medium within the primary combustion chamber to form a fluidizing bed, that is, in the range of 4 to 20 Gmf, preferably, in the range of 6 to 12 Gmf, whereas a mass flow of fluidizing air injected out of the air chamber 34 is arranged to be smaller than the former, in the range of 0 to 3 Gmf so that the fluidizing medium above the air chamber 34 is not accompanied by violent up-and-down movement but forms a descending moving bed in a weak fluidizing state.
  • This moving bed is spread at the lower portion thereof to reach the upper portion of the air chamber 33 and therefore encounters an injecting flow of fluidizing air having a large mass flow from the air chamber 33 and is blown up.
  • an injecting flow of fluidizing air having a large mass flow from the air chamber 33 and is blown up.
  • a part of the fluidizing medium at the lower portion of the moving bed is removed, and therefore, the moving bed is moved down due to its own weight.
  • the fluidizing medium blown up by the injecting flow of the fluidizing air from the air chamber 33 impinges upon the inclined partition wall 38 and is reversed and deflected, a majority of which falls on the upper portion of the moving bed to supplement the fluidizing medium of the moving bed moved downwardly.
  • the fluidizing medium moved into the thermal energy recovery chamber forms an angle of repose at the upper portion of the thermal energy recovery chamber, and a surplus portion thereof falls from the upper portion of the inclined partition wall 38 to the primary combustion chamber.
  • the fluidizing medium is subjected to heat exchange through the heat transfer tube 25 while moving down slowly, after which the medium is returned from the opening 39 into the primary combustion chamber.
  • the descending recycling amount and the thermal energy recovery amount of the fluidizing medium within the thermal energy recovery chamber are controlled by the amount of diffusing air blown into the thermal energy recovery chamber in a way similar to that of the embodiment shown in Fig. 1.
  • controlling is effected by the amount of air blown from the air diffuser 32, and the mass flow thereof is arranged to be in the range of 0 to 3 Gmf, preferably 0 to 2 Gmf.
  • Coal as fuel is supplied to the portion above the air chamber 34 wherein the descending moving bed is formed within the primary combustion chamber 23 whereby the coal is whirled and circulated within the fluidized bed of the primary combustion chamber and incinerated under excellent conditions of combustibility.
  • exhaust gas is directed to a cyclone 27 after being discharged from the boiler.
  • the particles collected at the cyclone 27 pass through a double damper 28 and are introduced into a hopper 30 together with coal parallelly supplied. They are mixed and supplied by a screw feeder 31 to the descending moving bed in the primary combustion chamber 23, that is, a portion above the air chamber 34, to contribute to the combustion of unburnt substance (char) in the collected particles and reduction in NOx.
  • the particles collected at the cyclone 27 may be supplied independently of coal, unlike the supply device shown in Fig. 2, and the particles and coal may be fed by an airborne means instead of the screw feeder.
  • a convection heat transfer surface means 26 is provided to effect thermal energy recovering.
  • a heat insulating material 37 such as a refractory material is mounted on the lower portion of the convection heat transfer surface means 26 and side of the water cooling furnace wall opposing the combustion chamber as required in order to maintain the combustion temperature of the free board at a constant temperature, preferably 900°C, and an air inlet 40 is provided for the purpose of secondary combustion to effectively reduce CO or the like.
  • Fig. 3 shows a still another embodiment of the present invention. Basically, it is constructed unitarily to incorporate a thermal energy recovery chamber shown in Fig. 2 symmetrically opposed in positions.
  • a thermal energy recovery chamber shown in Fig. 2 symmetrically opposed in positions.
  • an air chamber 53 having a small mass flow of blown air is positioned centrally, and air chambers having a large mass flow are arranged as chambers 52 and 54. Therefore the flowing stream of fluidizing medium caused by air blown out of the air chambers 52 and 54 is reversed by inclined partition walls 58 and 58' and falls on the central portion.
  • the flow is thence formed into a descending moving bed and reaches the portion above the air chamber 53, where it is divided into left and right portions, which are again blown up. Accordingly, two symmetrical whirling flows are present in the fluidized bed within the primary combustion chamber.
  • the coal and the particles collected at the cyclone are supplied to the central descending moving bed.
  • the supply position is indicated by a marking * within the primary combustion chamber, and the supplying direction is vertical relative to the paper surface. While the particles collected at the cyclone and coal are mixed and supplied by a screw feeder 51 in an embodiment shown in Fig. 3, it is to be noted that they may be supplied independently from each other, though not shown, or an airborne supply means may be employed.
  • the descending recycling amount of the fluidizing medium within the thermal energy recovery chambers is controlled by the amount of diffusing air introduced from air diffusers 60 and 60' in a manner similar to that of the diffuser shown in Fig. 2.
  • the fluidizing medium after being heat exchanged by heat transfer tubes 45 and 45', passes through openings 59 and 59' to return into the primary combustion chamber.
  • a convection heat transfer surface means 46 is provided at a portion above the free board portion to effect heat exchange.
  • a heat insulating material 57 such as a refractory material is mounted as required on the convection heat transfer surface means 46 and the side of the water cooling furnace wall opposing the combustion chamber in order to maintain the combustion temperature in the free board at a constant temperature, preferably, 900°C, and an air inlet 61 is provided for the purpose of secondary combustion to effectively reduce CO or the like.
  • thermal energy recovery from exhaust gas is carried out by a group of heat transfer tubes provided downstream of the free board portion and integrally with the free board portion.
  • Fig. 11 is a longitudinal sectional view of a composite recycling type fluidized bed boiler showing one embodiment of the present invention in which heat recovery from exhaust gas is carried out by a group of heat transfer tubes provided downstream of the free board portion and integrally with the free board portion.
  • Fig. 12 is a sectional view taken along the line A - A of Fig. 11. In Figs.
  • reference numeral 201 designates a boiler body, 202 an air diffusion nozzle for fluidization, 203 a primary combustion chamber, 204 and 204' thermal energy recovery chambers, 205 and 205' heat transfer tubes, 207 a cyclone, 208 a rotary valve, 209 a fuel supply tube, 210 a hopper, 211 a screw feeder for supplying fuel, 212, 213 and 214 air chambers, 218 and 218' partition walls, 219 and 219' openings at the lower portion of the thermal energy recovery chamber, 220 a secondary air introducing tube, 229 an outlet for exhaust gas, 230 a steam drum, 231 a water drum, 232 a convection heat transfer chamber, 233, 234 and 235 partition walls in the convection heat transfer chamber, 236 vaporization tubes, 237 a water pipe wall, 238 a bottom of the convection heat transfer chamber, 239 a screw conveyor, 240 an exhaust pipe for the convection heat transfer chamber, and 247, 247,
  • exhaust gas discharged out of the exhaust gas outlet 229 in the free board portion is introduced into the convection heat transfer chamber 232 having a group of vaporization tubes provided between the steam drum 330 and the water drum 231, heat-exchanged with water in the group of vaporization tubes during flowing toward the downstream of the convection chamber in the direction as indicated by the arrow due to the presence of the partition walls arranged within the convection heat transfer chamber, cooled to 250 to 400°C and thereafter introduced into the cyclone 207 via the exhaust pipe 240 so that fine particles containing char are collected at the cyclone and the gas is then discharged into the atmosphere.
  • the fine particles containing the char collected at the cyclone are returned via the rotary valve 208 and a charging opening to a portion directly above the descending moving bed of the primary combustion chamber 203, the charging opening being the same for fuel such as coal supplied to the boiler via the charging opening 209, the hopper 210 and the screw feeder 211.
  • the fluidizing medium having a relatively large grain size separated in the convection heat transfer portion 232 and grains containing desulfurizer and char are gathered to a V-shaped bottom at the lower portion of the convection heat transfer portion and then returned by the screw conveyor 239 to the portion directly above the descending moving bed on the side opposite the fuel supply side in the primary combustion chamber.
  • the secondary air is blown in a reverse direction to the flowing direction of the exhaust gas flowing into the convection heat transfer portion from the free board portion thereby causing a whirling flow in the free board portion so that oxygen and exhaust gas are efficiently stirred and mixed to effectively promote reduction of CO.
  • Fig. 13 is a sectional view corresponding to Fig. 12, and reference numerals in Fig. 13 are the same in meaning as those shown in Fig. 12 except that 238' designates a V-shaped bottom of the convection heat transfer portion and 239' designates a screw conveyor.
  • This embodiment is different from the boilers shown in Figs. 11 and 12 only in that two V-shaped bottoms 238 and 238' (W-shaped bottoms) are provided at the lower portion of the convection heat transfer chamber, and that particles containing relatively large char collected at the V-shaped bottoms 238 and 238' are returned by screw conveyors 239 and 239' to the portion directly above the descending moving beds 204 and 204' of the fluidizing medium in the thermal energy recovery chambers provided at opposite sides of the combustion chamber.
  • V-shaped bottoms 238 and 238' W-shaped bottoms
  • Fig. 14 shows still another embodiment of the present invention.
  • Reference numerals used in Fig. 14 are the same in meaning as those used in Fig. 11 except that the reference numeral 241 designates a conduit.
  • the embodiment shown in Fig. 14 is merely different from that of Fig. 11 in that fine particles containing char collected at the cyclone 207 are directed to the screw feeder 239 at the lower portion of the convection heat transfer portion 232 by the conduit 241 and then returned together with the particles containing a relatively large char collected at the convection heat transfer portion to the portion directly above the descending moving bed in the primary combustion chamber.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)
  • Invalid Beds And Related Equipment (AREA)
  • Laminated Bodies (AREA)

Abstract

Une partie du lit fluidisé de la chaudière à lit fluidisé est divisée par une cloison en une chambre de combustion principale et une chambre de récupération de chaleur, et on prévoit au moins deux types de chambre à air, c'est-à-dire une chambre à air conférant une vitesse de fluidisation élevée à un milieu de fluidisation et une chambre à air lui conférant une faible vitesse de fluidisation. En combinant l'air présentant différentes vitesses de fluidisation et éjecté par lesdites chambres à air, on obtient un écoulement tourbillonnaire dans le milieu de fluidisation à l'intérieur de la chambre de combustion principale, et un écoulement de milieu de fluidisation se produit entre la chambre de combustion principale et la chambre de récupération de chaleur. A l'intérieur de la chambre de récupération de la chaleur, la récupération de la chaleur contenue dans un gaz d'échappement s'effectue dans une partie de plaque libre ou en aval de la partie de plaque libre dans une chaudière à lit fluidisé à circulation interne pour abaisser le milieu de fluidisation sous forme de lit fluidisé, et après l'abaissement de la température du gaz d'échappement, ce gaz ainsi refroidi est introduit dans un cyclone, et le charbon sous forme de fines particules recueillies par le cyclone est renvoyé dans la partie située immédiatement au-dessus, ou à l'intérieur, de la couche descendante de milieu de fluidisation dans la chambre de combustion principale et/ou dans la chambre de récupération de chaleur. Etant donné que le charbon est renvoyé immédiatement au-dessus ou à l'intérieur de la couche descendante de milieu de fluidisation, il ne se disperse pas immédiatement vers la partie de plaque libre. Par conséquent, bien qu'il soit constitué de fines particules, il se sédimente et se diffuse suffisamment dans le lit fludisé, ce qui permet d'obtenir une réduction du NOx produit par la combustion du charbon ou similaire à l'intérieur de la couche.
EP89909857A 1988-08-31 1989-08-30 Chaudiere a lit fluidise a circulation composite Expired - Lifetime EP0431163B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP215135/88 1988-08-31
JP21513588 1988-08-31
PCT/JP1989/000883 WO1990002293A1 (fr) 1988-08-31 1989-08-30 Chaudiere a lit fluidise a circulation composite

Publications (3)

Publication Number Publication Date
EP0431163A1 true EP0431163A1 (fr) 1991-06-12
EP0431163A4 EP0431163A4 (en) 1992-05-20
EP0431163B1 EP0431163B1 (fr) 1995-12-06

Family

ID=16667285

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89909857A Expired - Lifetime EP0431163B1 (fr) 1988-08-31 1989-08-30 Chaudiere a lit fluidise a circulation composite

Country Status (9)

Country Link
EP (1) EP0431163B1 (fr)
KR (1) KR100229691B1 (fr)
CN (1) CN1017469B (fr)
AT (1) ATE131271T1 (fr)
AU (1) AU4199889A (fr)
CA (1) CA1332685C (fr)
DE (1) DE68925033T2 (fr)
MY (1) MY104683A (fr)
WO (1) WO1990002293A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0619455A2 (fr) * 1993-03-03 1994-10-12 Ebara Corporation Chaudière à lit fluidisé sous pression à circulation interne
EP2997307B1 (fr) 2013-05-14 2017-07-05 Valmet Technologies Oy Dispositif et procédé pour chaudière à lit fluidisé
CN111836996A (zh) * 2018-03-13 2020-10-27 荏原环境工程株式会社 流化床热回收装置
EP3957909A1 (fr) 2020-08-20 2022-02-23 Steinmüller Engineering GmbH Four à lit fluidisé asymétrique destiné à la combustion de matières

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100417862C (zh) * 2005-12-09 2008-09-10 清华大学 一种卧式循环流化床燃烧设备及其循环燃烧方法
FI122040B (fi) * 2009-11-10 2011-07-29 Foster Wheeler Energia Oy Menetelmä ja järjestely polttoaineen syöttämiseksi kiertoleijupetikattilaan
CN104136842B (zh) * 2012-02-13 2016-05-11 荏原环境工程有限公司 流动层锅炉的层内传热管
JP5992322B2 (ja) * 2012-12-28 2016-09-14 住友重機械工業株式会社 循環流動層ボイラ
CN103090397B (zh) * 2013-01-16 2015-09-09 河南科技大学 一种污泥与煤流化床混烧反应器
CN104279548A (zh) * 2013-07-12 2015-01-14 李雨田 集能换热式环保锅炉
CN105444160B (zh) * 2014-08-29 2019-01-08 中国科学院工程热物理研究所 循环流化床细粉灰燃烧装置
CN106196124A (zh) * 2016-08-23 2016-12-07 苏州泰盛新绿节能环保科技有限公司 一种降低排烟氧含量的燃煤锅炉组件
CN107631293A (zh) * 2017-10-27 2018-01-26 湘潭锅炉有限责任公司 一种循环流化床锅炉
CN114353049A (zh) * 2021-12-25 2022-04-15 江苏中科重工股份有限公司 一种锅炉疏水扩容器汽水热量回收方法及设备

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GB1081739A (en) * 1963-12-03 1967-08-31 Container Corp Disposal of waste liquors and recovery of inorganic chemicals therefrom
DE2449798A1 (de) * 1974-10-19 1976-04-29 Rheinstahl Ag Wirbelschichtofen fuer die verbrennung von teilweise entwaessertem schlamm
GB2046886A (en) * 1979-01-31 1980-11-19 Foster Wheeler Power Prod Fluidized bed fired fluid heaters
EP0124636A1 (fr) * 1983-05-10 1984-11-14 GebràœDer Sulzer Aktiengesellschaft Four à couche fluidisée
GB2151503A (en) * 1981-12-15 1985-07-24 William Benedict Johnson Fluidized bed combustion apparatus and method of carrying out fluidized bed combustion
EP0230309A2 (fr) * 1986-01-21 1987-07-29 Ebara Corporation Chaudière à lit fluidisé et procedé pour sa commande

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JPS57139205A (en) * 1981-02-23 1982-08-28 Babcock Hitachi Kk Fluidized bed furnace
JPS62141408A (ja) * 1985-12-13 1987-06-24 Mitsubishi Heavy Ind Ltd 循環型流動床燃焼装置
JPS63143409A (ja) * 1986-12-03 1988-06-15 Mitsubishi Heavy Ind Ltd 循環流動層ボイラ

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GB1081739A (en) * 1963-12-03 1967-08-31 Container Corp Disposal of waste liquors and recovery of inorganic chemicals therefrom
DE2449798A1 (de) * 1974-10-19 1976-04-29 Rheinstahl Ag Wirbelschichtofen fuer die verbrennung von teilweise entwaessertem schlamm
GB2046886A (en) * 1979-01-31 1980-11-19 Foster Wheeler Power Prod Fluidized bed fired fluid heaters
GB2151503A (en) * 1981-12-15 1985-07-24 William Benedict Johnson Fluidized bed combustion apparatus and method of carrying out fluidized bed combustion
EP0124636A1 (fr) * 1983-05-10 1984-11-14 GebràœDer Sulzer Aktiengesellschaft Four à couche fluidisée
EP0230309A2 (fr) * 1986-01-21 1987-07-29 Ebara Corporation Chaudière à lit fluidisé et procedé pour sa commande

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See also references of WO9002293A1 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0619455A2 (fr) * 1993-03-03 1994-10-12 Ebara Corporation Chaudière à lit fluidisé sous pression à circulation interne
EP0619455A3 (fr) * 1993-03-03 1995-03-08 Ebara Corp Chaudière à lit fluidisé sous pression à circulation interne.
EP2997307B1 (fr) 2013-05-14 2017-07-05 Valmet Technologies Oy Dispositif et procédé pour chaudière à lit fluidisé
CN111836996A (zh) * 2018-03-13 2020-10-27 荏原环境工程株式会社 流化床热回收装置
CN111836996B (zh) * 2018-03-13 2022-11-18 荏原环境工程株式会社 流化床热回收装置
EP3957909A1 (fr) 2020-08-20 2022-02-23 Steinmüller Engineering GmbH Four à lit fluidisé asymétrique destiné à la combustion de matières

Also Published As

Publication number Publication date
WO1990002293A1 (fr) 1990-03-08
EP0431163A4 (en) 1992-05-20
KR100229691B1 (ko) 1999-11-15
CA1332685C (fr) 1994-10-25
DE68925033D1 (de) 1996-01-18
KR900700822A (ko) 1990-08-17
AU4199889A (en) 1990-03-23
ATE131271T1 (de) 1995-12-15
CN1017469B (zh) 1992-07-15
MY104683A (en) 1994-05-31
EP0431163B1 (fr) 1995-12-06
CN1041646A (zh) 1990-04-25
DE68925033T2 (de) 1996-05-15

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