JP2014234976A - Fluid medium collector for circulating fluidized bed boiler - Google Patents

Abstract

[PROBLEMS] To suppress the accumulation of fly ash and fluid medium in a duct even when the gas flow rate is low at low load operation, and to shorten the installation work period and the installation work cost and material cost. A fluid medium collector is provided. SOLUTION: The exhaust gas G, fluid medium S, and fly ash, which are continuously connected to the horizontal portion 2a of the combustion chamber outlet 1c of the furnace body 1 and are discharged downward from the combustion chamber outlet duct 2, receive gravity acceleration and centrifugal acceleration. The fluidized medium recovery unit 4 of the circulating fluidized bed boiler that separates the exhausted gas G and fly ash and the fluidized medium S and collects the fluidized medium S includes a cylindrical body 4A having an exhaust gas outlet 4a on the upper end surface, and a cylindrical body 4A is provided at the lower end, and gradually decreases in diameter as it goes downward. The conical portion 4B has a fluid medium outlet 4b formed at the lower end surface, and the vertical portion 2b of the combustion chamber outlet duct 2 faces downward via the expansion joint 3. The inlet duct 4C is connected in an inclined posture and connected in a tangential direction to the cylindrical body 4A. [Selection] Figure 1

Description

  The present invention relates to an improvement of a fluidized medium recovery unit of a circulating fluidized bed boiler that uses biomass, coal, or the like as fuel and is used as a steam boiler mainly for power generation, and more particularly, exhaust gas and fluidized medium in the fluidized medium recovery unit. By improving the ducts that lead to etc., even when extremely low load operation is performed, the fluidized medium can be smoothly dropped, and even if the gas flow rate is slow due to low load operation, The present invention relates to a fluidized medium recovery device for a circulating fluidized bed boiler that can suppress the accumulation of fluidized media and can reduce the installation work period and the installation work cost and material cost.

  In general, circulating fluidized bed boilers have excellent combustion performance for fuels such as biomass, coal, RDF, wood waste, municipal waste, industrial waste, and sludge, and are used as steam boilers for power generation in waste incineration facilities. Has been.

  Conventionally, as this type of circulating fluidized bed boiler, for example, those disclosed in Japanese Patent Laid-Open No. 10-220708 (Patent Document 1) and Japanese Patent Laid-Open No. 2001-235101 (Patent Document 2) are known.

  FIG. 9 shows an example of a conventional circulating fluidized bed boiler. The circulating fluidized bed boiler is connected to a furnace body 20 having a fluidized bed 20a and a combustion chamber 20b, and a furnace body 20 via a duct 21, It is comprised from the cyclone 23 which has the inner cylinder 22, and the loop seal part 24 etc. which were connected to the cyclone 23 and the furnace main body 20, Constituent material (water pipe wall etc.), such as the furnace main body 20, the cyclone 23, and the loop seal part 24 ) And high-temperature and high-pressure superheated steam for power generation are generated by heat absorbed by a heat exchanger or the like disposed in a flue.

  That is, according to the circulating fluidized bed boiler, the fuel supplied into the furnace from the fuel supply port 20c is separated from the fluid medium S such as fluidized sand by the primary air ejected from the fluid nozzle (not shown) in the fluidized bed 20a. Combusts while being stirred and mixed.

  Incineration residues such as combustion gas and fly ash generated by combustion are blown up together with the fluidized medium S from the fluidized bed 20a to the combustion chamber 20b, where they are supplied to the combustion chamber 20b while being agitated and mixed with the fluidized medium S. After the combustion gas and unburned components are completely burned by the secondary air, they are introduced into the cyclone 23 through the duct 21.

  The exhaust gas G containing the fly ash and the like introduced into the cyclone 23 and the fluid medium S are separated into the fluid medium S and the exhaust gas G containing the fly ash by a centrifugal separation action.

  The separated fluid medium S is returned from the cyclone 23 to the fluidized bed 20a of the furnace body 20 through the downcomer 25, the loop seal portion 24, and the return port 20d of the fluid medium S, and the retained heat of the fluid medium S is retained. After being reused, the exhaust gas G containing fly ash and the like is recovered from the cyclone 23 through the flue through a heat exchanger and the like, and the fly ash and the like are removed by an exhaust gas treatment device such as a bag filter. Released from the chimney into the atmosphere.

  Since the circulating fluidized bed boiler has a large flow velocity difference between the combustion gas rising in the furnace body 20 and the fluid medium S, the fuel and the fluid medium S are vigorously stirred and mixed throughout the furnace, and the combustion reaction is performed. Progresses rapidly. As a result, the fuel can be completely burned with a low excess air ratio, and it has excellent effects such as improvement of boiler efficiency by reducing unburned material loss and low NOx combustion by a low excess air ratio. It is.

By the way, in the circulating fluidized bed boiler adopting a standard cyclone, the furnace body 20 and the cyclone 23 are usually connected in a continuous manner by a horizontal duct 21, but in this case, if low load combustion is performed, Since the gas flow rate in the gas chamber 21 becomes slow and the gas temperature also decreases, there is a problem that the fly ash and the fluid medium S are accumulated and solidified in the duct 21 and the duct 21 is easily blocked. This problem can also occur when the fuel introduced into the furnace is changed.
Moreover, when it transfers to high load combustion in the state in which the fly ash and the fluid medium S accumulated and solidified in the duct 21, since the opening area in the duct 21 is narrow, the gas flow velocity in the duct 21 rises rapidly, The fluid medium S contained in the exhaust gas G causes wear on the inner surface of the peripheral wall of the cyclone 23.

In some circulating fluidized bed boilers, in order to suppress the accumulation of fly ash and the like in the duct, there are some in which the duct is inclined as in JP-A-11-082968 and JP-A-2005-058872.
However, when the entire duct is simply inclined and connected to the cyclone, the structure of the boiler water pipe is difficult, and the furnace body and the cyclone forming the combustion chamber need to be formed integrally.
Further, when an expansion joint (not shown) is provided in the middle of the duct, fly ash and a fluid medium are likely to be deposited on the expansion joint portion, which may cause a reduction in performance and damage of the expansion joint.

  In addition, in general cyclones that adopt horizontal ducts and cyclones that adopt inclined ducts, the connection position with the combustion chamber is in the transverse direction of the cyclone, and not only the diameter of the cyclone but also the duct when transporting by land by truck Therefore, it is necessary to take measures such as making the structure in which the duct can be disassembled and assembled and increasing the division position of the duct.

Furthermore, in the circulating fluidized bed boiler, when the combustion chamber and the cyclone boiler water pipe are configured integrally, in order to cope with the difference in the thermal expansion of the boiler, a strut is constructed to surround the entire circulating fluidized bed boiler, and the uppermost beam However, the circulating fluidized bed boiler itself is a heavy article having a height of 20 m to 40 m and requires a very large support.
In addition, when the circulating fluidized bed boiler is suspended, it is necessary to suspend the installation from the upper part after constructing the support that surrounds the entire circulating fluidized bed boiler, so an extra large crane is required for the installation work. The installation cost will be high.

JP-A-10-220708 JP 2001-235101 A JP 11-082968 A JP 2005-058872 A

  The present invention has the above-mentioned problems in a circulating fluidized bed boiler using a conventional cyclone that employs a conventional horizontal duct or a cyclone that employs an inclined duct, that is, (1) the gas flow velocity is reduced at low load operation. Sometimes fly ash or fluid medium accumulates and solidifies in the duct and closes the duct. (2) When an expansion joint is interposed in the middle of the duct, fly ash or fluid medium accumulates on the expansion joint. (3) Since the circulating fluidized bed boiler has a suspended structure, it is intended to solve problems such as the need for very large struts and high material and installation costs. Its purpose is to improve the duct that guides the exhaust gas and fluid medium in the fluid medium collector, so that the fluid medium can be smoothly dropped even in extremely low load operation, and the load can be reduced. Ga Even when the flow rate is slow, the accumulation of fly ash and fluid medium in the duct can be suppressed, and the circulating fluidized bed boiler that can shorten the installation work period and the installation work cost and material cost can be reduced. A fluid medium collector is provided.

  The invention of claim 1 of the present invention is a combustion comprising a horizontal portion connected to the combustion chamber outlet of a furnace body having a fluidized bed and a combustion chamber and having a minimum length in terms of structure, and a vertical portion continuously provided downward to the horizontal portion. One or more connected to the chamber outlet duct, receiving the exhaust gas, fluid medium, fly ash discharged downward from the combustion chamber outlet duct, and separating into exhaust gas, fly ash and fluid medium by gravity acceleration and centrifugal acceleration, In the fluidized medium recovery device of the circulating fluidized bed boiler for recovering the fluidized medium from the exhaust gas, the fluidized medium recovery device is provided at a lower end portion of the cylindrical body portion having a cylindrical body portion having an exhaust gas outlet formed at an upper end surface thereof, The diameter is gradually reduced as it goes, and the conical part having a fluid medium outlet formed at the lower end surface is connected to the vertical part of the combustion chamber outlet duct in a downward inclined posture through an expansion joint, and the cylinder body is tangentially connected thereto. Connection The consists of a inlet duct is characterized in that is constituted by integrally the cylindrical barrel and the inlet duct.

  The invention of claim 2 of the present invention is characterized in that, in the invention of claim 1, the inclination angle α of the inlet duct is set to 10 ° to 45 °.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the cylindrical body and the inlet duct of the fluid medium collector have a water pipe panel structure, and the water pipe of the cylindrical body and the water pipe of the inlet duct It is characterized in that it is configured integrally.

  The invention of claim 4 of the present invention is the invention of claim 1, claim 2 or claim 3, wherein the size of the outer shape of the fluid medium collector not including the inlet duct is 2500 mm or less, and the inlet duct is included. It is characterized in that the size of the outer shape of the fluid medium collector is set to 3800 mm or less.

  The invention of claim 5 of the present invention is the invention of claim 1, claim 2, claim 3 or claim 4, wherein the downcomer is connected to the fluid medium outlet of the fluid medium collector via an expansion joint, The exhaust gas outlet duct is connected to the exhaust gas outlet of the fluid medium recovery device via an expansion joint, and the fluid medium recovery device is self-supported by an intermediate support structure with a support.

  The invention of claim 6 of the present invention is the invention of claim 1, claim 2, claim 3, claim 4 or claim 5, wherein the inlet duct is parallel to the bottom face in the inlet duct and close to the bottom face. A feature is that an air injection nozzle is provided, and air or a mixed fluid of air and at least one of a supplementary fluid medium, a desulfurization agent, and a clinker inhibitor is supplied from the air injection nozzle.

  The circulating fluid bed collector of the circulating fluidized bed boiler of the present invention has the inlet duct connected to the cylindrical body in a downward inclined posture, so that even when performing extremely low load operation, the falling of the fluid medium becomes smooth, It is possible to avoid clogging caused by the fluid medium gathering and falling on the conical portion of the fluid medium collector.

  In the circulating fluidized bed boiler according to the present invention, since the inlet duct is connected to the vertical portion of the combustion chamber outlet duct via the expansion joint, the expansion joint portion can be obtained even when the gas flow rate is low due to low load operation. Therefore, it is possible to avoid troubles caused by damage to the expansion joint.

  In the circulating fluidized bed boiler of the present invention, an inlet duct is connected to a cylindrical body in a downward inclined posture and in a tangential direction, and exhaust gas, fluidized medium and fly ash are directed downwardly into the fluidized medium collector from the inlet duct. Since it is introduced in a tangential direction in an inclined posture, the fluid medium can be separated and collected by gravity acceleration and centrifugal acceleration in the fluid medium collector, and it is used in conventional general cyclones. The cylinder becomes unnecessary, and it is possible to reduce the equipment cost and avoid troubles such as deformation, dropout and blockage of the inner cylinder.

  In the circulating fluidized bed boiler according to the present invention, the cylindrical body and the inlet duct are integrally formed, so that the installation work period can be greatly shortened.

  In the circulating fluidized bed boiler according to the present invention, the cylindrical body and the inlet duct have a water pipe panel structure, and the water pipe (boiler water pipe) of the cylindrical body and the water pipe (boiler water pipe) of the inlet duct are integrally configured. As a result, it is possible to reduce the number of water pipe welding processes and reduce the installation period.

  In the circulating fluidized bed boiler according to the present invention, an inlet duct is connected to the vertical part of the combustion chamber outlet duct via an expansion joint, and a downcomer is connected to the fluid medium outlet of the fluidized medium recovery unit via an expansion joint. In addition to connecting, the exhaust gas outlet duct is connected to the exhaust gas outlet of the fluid medium recovery device via an expansion joint, and the fluid medium recovery device is self-supporting by an intermediate support structure with a support column. Can be self-supporting with an intermediate support structure, eliminating the need for supporting columns that surround the entire circulating fluidized bed boiler, simplifying the supporting columns, greatly reducing material costs and installation work costs, and shortening the construction period .

In the circulating fluidized bed boiler according to the present invention, the inlet medium is provided with an air injection nozzle at a position parallel to the bottom surface of the inlet duct and close to the bottom surface, and air is supplied from the air injection nozzle. Therefore, the unburned matter can be completely burned in the fluid medium recovery unit, and accumulation of fly ash and the like in the inlet duct can be prevented.
Moreover, the fluidized medium recovery device of the circulating fluidized bed boiler of the present invention is charged with the supplementary fluid medium, desulfurizing agent, and clinker inhibitor together with air from the air charging nozzle, so that it is directly charged into the combustion chamber. It is possible to suppress a decrease in the furnace temperature, and it is possible to clean the inside of the inlet duct by the polishing effect of a replenishing fluid medium, a desulfurizing agent, etc., and to prevent the inlet duct from being blocked.

1 is a schematic front view of a circulating fluidized bed boiler incorporating a fluid medium recovery device according to an embodiment of the present invention. It is a schematic plan view of a circulating fluidized bed boiler. 1 shows a fluid medium recovery device according to an embodiment of the present invention, wherein (A) is a schematic front view of the fluid medium recovery device, and (B) is a schematic plan view thereof. FIG. 3 shows a fluid medium recovery device shown in FIG. 3, (A) is a schematic right side view of the fluid medium recovery device, and (B) is a schematic plan view thereof. 1 is a schematic front view of a circulating fluidized bed boiler using a plurality of fluid medium recovery devices according to an embodiment of the present invention and connecting each fluid medium recovery device to a furnace body through a plurality of combustion chamber outlet ducts. It is a schematic plan view of the circulating fluidized bed boiler shown in FIG. 1 is a schematic longitudinal sectional view of a circulating fluidized bed boiler using a plurality of fluid medium collectors according to an embodiment of the present invention and connecting a plurality of fluid medium collectors to a furnace body via one combustion chamber outlet duct. It is a schematic plan view of the circulating fluidized bed boiler shown in FIG. It is a schematic front view of the conventional circulating fluidized bed boiler.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 show a circulating fluidized bed boiler incorporating a fluidized medium recovery device 4 according to an embodiment of the present invention. The circulating fluidized bed boiler includes a furnace body 1 having a fluidized bed 1a and a combustion chamber 1b, A cylindrical fluid recovery unit 4 connected to the main body 1 via a combustion chamber outlet duct 2 and an expansion joint 3, a loop seal portion 6 connected to the fluid recovery unit 4 via a downcomer 5, and a loop Consists of a circulation duct 7 and the like connecting the seal portion 6 and the furnace body 1, absorbed heat by components (water pipe panel, etc.) of the furnace body 1, and absorbed heat by a heat exchanger disposed in the flue In this way, high-temperature and high-pressure superheated steam for power generation is generated.

Specifically, the furnace body 1 has a quadrangular cross-sectional shape formed by a water tube panel in which adjacent water tubes are connected in an airtight manner via fin plates, and the primary air is contained in the inside. Are provided with a fluidized bed 1a provided with a plurality of flow nozzles (not shown) for blowing air and a combustion chamber 1b for blowing secondary air. The outer surface of the water tube panel forming the furnace body 1 is covered with a heat insulating material and a casing made of a steel plate. Further, combustion gas in the furnace and blown fly ash blown up in the upper position of the side wall of the furnace body 1, A combustion chamber outlet 1 c for discharging the fluid medium S is formed, and a return port 1 d for the fluid medium S separated from the exhaust gas G is formed at a lower position of the side wall of the furnace body 1.

In addition, refractory materials such as refractory bricks and castable refractories are lined on the inner surface of the portion facing the fluidized bed 1a of the water tube panel, and wear of the water tube panel due to the fluidized fluid medium S is prevented. .
Further, the portion of the water tube panel facing the combustion chamber 1b may be in a bare tube state, or a protective coating is formed by spraying a wear-resistant metal, and the water tube panel is protected by this protective coating. good.

In the above embodiment, the furnace main body 1 has a water tube panel structure. However, in other embodiments, the furnace main body 1 may have a refractory wall structure in which a refractory is lined in a casing.
In the above-described embodiment, the cross-sectional shape of the furnace body 1 is a quadrangle. However, in other embodiments, the cross-sectional shape of the furnace body 1 may be a circle.

The combustion chamber outlet duct 2 is formed in a square tube shape and has a water tube panel structure or a refractory structure. The combustion chamber outlet duct 2 is connected to the combustion chamber outlet 1c of the furnace body 1 and has a rectangular tube shape having a minimum length in terms of structure. It consists of a horizontal portion 2a and a rectangular cylindrical vertical portion 2b that is connected to the horizontal portion 2a downward by 90 °.
The combustion chamber outlet duct 2 is connected to the combustion chamber outlet 1c of the furnace body 1 with the bottom wall of the horizontal portion 2a inclined downward with respect to the combustion chamber 1b, and the bottom of the horizontal portion 2a. The horizontal portion 2a of the wall is formed so as to have a minimum length in terms of structure.
Further, a replenishing fluid medium such as fluid sand, a desulfurizing agent (limestone, dolomite, etc.) and a powdery clinker inhibitor (Mg, Si, Ca, Al, etc.) are provided at the upper end of the vertical portion 2b of the combustion chamber outlet duct 2. The compound 1) is provided with an inlet 1c, and any one or more of the replenishing fluid medium, the desulfurizing agent, and the clinker inhibitor can be simultaneously introduced from the inlet 1c by natural fall. It is like that.

  As shown in FIGS. 3 and 4, the fluid medium recovery unit 4 is provided at a cylindrical body part 4 </ b> A having an exhaust gas outlet 4 a having a flange structure on the upper end surface, and at a lower end part of the cylindrical body part 4 </ b> A, and goes downward. The cylinder body is gradually reduced in diameter and connected in a downward inclined posture to the conical portion 4B in which the fluid medium outlet 4b having a flange structure is formed on the lower end surface and the vertical portion 2b of the combustion chamber outlet duct 2 via the expansion joint 3. The cylindrical duct 4A and the inlet duct 4C are integrally formed with an inlet duct 4C connected to 4A in the tangential direction.

Specifically, the cylindrical body portion 4A has a circular water tube panel structure in which the cross-sectional shape formed by connecting adjacent water tubes in an airtight manner via fins is formed at the center of the upper end surface. The exhaust gas outlet 4a having a flange structure is formed.
The cylindrical body portion 4A is formed to have a relatively high height, and the exhaust gas G and the fluid medium S are separated in the cylindrical copper portion. Therefore, a member corresponding to the inner cylinder of the conventional cyclone is not provided in the cylindrical copper portion.

The conical portion 4B has a conical shape that gradually decreases in diameter as it goes downward, and has a refractory structure composed of a combination of a steel plate and a heat-resistant material. A flange-shaped fluid medium outlet 4b is formed on the lower end surface. Has been.
The conical portion 4B is formed to have a very low height, performs only the guiding function of the fluid medium S, and does not have the function of separating the exhaust gas G and the fluid medium S at all.

The inlet duct 4C is formed integrally with the cylindrical body 4A, and is connected to the rectangular cylindrical vertical part 4C 'having the exhaust gas inlet 4c having a flange structure, and the lower end of the vertical part 4C'. 4A, and a rectangular tube-like inclined portion 4C ″ connected in a tangential direction with a downward inclined posture.
Further, the vertical portion 4C ′ of the inlet duct 4C is configured as a refractory structure made of a combination of a steel plate and a heat-resistant material, while the inclined portion 4C ″ of the inlet duct 4C has the same water tube panel structure as the cylindrical body 4A. The water pipe of the cylindrical body portion 4A and the water pipe of the inclined portion 4C ″ are integrally formed.
Further, one or a plurality of air injection nozzles 8 are provided in the upstream side portion of the inlet duct 4C, and air or air and supplementary fluid medium S, desulfurization agent, and clinker inhibitor are supplied from the air injection nozzle 8. A fluid mixture with at least one of them can be introduced. The air injection nozzle 8 is provided at a position parallel to the bottom surface in the inclined portion 4C ″ and as close as possible to the bottom surface of the vertical portion 4C ′ of the inlet duct 4C, and is deposited on the bottom surface in the inclined portion 4C ″. Ashes and fluid medium S can be blown away.

The inclination angle α of the inlet duct 4C is appropriately determined from the flow rate of the exhaust gas G in the inlet duct 4C and the required classifying performance of the fluid medium recovery unit 4.
The cross-sectional area (height × width) of the inlet duct 4C is set so that the flow rate of the exhaust gas G flowing through the inlet duct 4C becomes a predetermined value.
In this embodiment, the inclination angle α of the inlet duct 4C is set to 10 ° to 45 °, and the cross-sectional area of the inlet duct 4C is set so that the flow velocity of the exhaust gas G in the inlet duct 4C is the maximum load combustion of the circulating fluidized bed boiler. The time is set to 20 m / s or less, and the lower limit at the time of low load combustion is not provided. These values are determined from test results using an actual machine.

The exhaust gas inlet 4c of the fluid medium collector 4 is connected to the vertical portion 2b of the combustion chamber outlet duct 2 via the expansion joint 3, and the fluid medium outlet 4b of the fluid medium collector 4 is connected to the water tube panel via the expansion joint 3. The exhaust gas outlet 4 a of the fluidized medium recovery device 4 is connected to the cylindrical exhaust gas outlet duct 9 via the expansion joint 3 to the cylindrical downcomer 5 having a structure or a refractory structure.
Therefore, the fluid medium recovery device 4 is self-supporting with an intermediate support structure by a plurality of columns 10 separately from the furnace body 1 by interposing the expansion joints 3 in the inlet duct 4C, the downcomer 5 and the exhaust gas outlet duct 9, respectively. Can be made. Along with this, the furnace body 1 can also be self-supporting with an intermediate support structure by a plurality of support columns 10.

Needless to say, the height and diameter of the fluidized medium recovery unit 4 are appropriately selected according to the capacity of the circulating fluidized bed boiler.
Further, the size of the outer shape of the fluid medium recovery unit 4 is set to such an extent that it does not hinder the conveyance by the truck.
In this embodiment, the size of the outer shape of the fluid recovery unit 4 that does not include the inlet duct 4C is set to 2500 mm or less, and the size of the outer shape of the fluid recovery unit 4 that includes the inlet duct 4C is set to 3800 mm or less. (See FIG. 4).

The loop seal portion 6 is configured as a trap-shaped box-shaped water tube panel structure or a refractory wall structure having a partition wall 6a and an overflow portion 6b therein, and a conical portion 4B of the fluid medium recovery unit 4 Is connected to the return port 1d of the furnace body 1 via a circulation duct 7 having a water tube panel structure or a refractory structure, and is connected to the inside of the furnace body 1 and the fluid medium collector 4 The fluid medium S separated and recovered while being sealed is returned to the fluidized bed 1a in the furnace body 1.
Further, fluidized air is supplied into the loop seal portion 6 from the bottom thereof, thereby forming a fluidized bed 1 a in the loop seal portion 6.

  Thus, according to the circulating fluidized bed boiler described above, fuel such as biomass and coal supplied from the fuel supply port (not shown) into the furnace is disposed at the bottom of the furnace body 1 in the fluidized bed 1a. The primary air ejected from the fluidized nozzle (not shown) combusts while being agitated and mixed with the fluid medium S such as fluidized sand.

  Incineration residues such as combustion gas and fly ash generated by combustion are blown up together with the fluidized medium S from the fluidized bed 1a to the combustion chamber 1b, where they are supplied to the combustion chamber 1b while being agitated and mixed with the fluidized medium S. After the combustion gas and unburned components are completely burned by the secondary air, they are introduced into the fluid medium collector 4 through the combustion chamber outlet duct 2, the expansion joint 3 and the inlet duct 4C.

At this time, since the length of the horizontal portion 2a of the combustion chamber outlet duct 2 is set to the minimum length in terms of structure, even if the gas flow velocity in the combustion chamber outlet duct 2 decreases during combustion load fluctuation or fuel change The fly ash and the fluid medium S can be prevented from being deposited and solidified in the combustion chamber outlet duct 2.
Further, since the inlet duct 4C is connected to the fluid medium collector 4 in a downward inclined posture, the fluid medium S can be smoothly dropped even when an extremely low load operation is performed.
Furthermore, since the inlet duct 4C is connected to the vertical portion 2b of the combustion chamber outlet duct 2 via the expansion joint 3, even if the gas flow rate is slow due to low load operation, fly ash or fluid medium S is formed in the expansion joint 3 portion. Is not said to accumulate.

  The exhaust gas G containing the fly ash and the like introduced into the fluid medium recovery unit 4 and the fluid medium S are separated into the fluid medium S and the exhaust gas G containing the fly ash and the like. That is, in the fluid medium collector 4, the exhaust gas G, the fluid medium S, and the like are introduced into the fluid medium collector 4 in a downward inclined posture and in a tangential direction. Therefore, due to the gravitational acceleration and the centrifugal acceleration similar to the cyclone, The heavy fluid medium S having a large particle diameter is divided below the fluid medium collector 4, and the light exhaust gas G and the light fly ash having a small particle diameter are separated above the fluid medium collector 4.

  In this fluid medium collector 4, the fluid medium S can be separated and recovered by gravity acceleration and centrifugal acceleration, so that the inner cylinder used in the conventional general cyclone becomes unnecessary, and the equipment cost is reduced. And troubles such as deformation, dropout and blockage of the inner cylinder can be avoided.

The separated fluid medium S is returned from the fluid medium collector 4 to the fluidized bed 1a of the furnace body 1 through the downcomer 5, the loop seal 6 and the circulation duct 7, and the retained heat possessed by the fluid medium S. Will be reused.
Further, the separated exhaust gas G including fly ash is recovered from the heat through the flue from the exhaust gas outlet duct 9 of the fluid medium recovery device 4 by a heat exchanger or the like, and is discharged by an exhaust gas processing device such as a bag filter. After the ash is removed, it is released from the chimney into the atmosphere.

  During operation of the circulating fluidized bed boiler, any one of the replenishing fluid medium S, the desulfurizing agent, or the clinker inhibitor is caused by natural fall from the inlet 1c provided at the upper end of the vertical portion 2b of the combustion chamber outlet duct 2. One or two or more are input simultaneously. In addition, air or a mixed fluid of air and at least one of a replenishing fluid medium, a desulfurizing agent, and a clinker inhibitor is also supplied from an air input nozzle 8 provided in the inlet duct 4C.

As a result, it is possible to suppress a decrease in the furnace temperature due to the direct introduction of the replenishing fluid medium, desulfurizing agent, and the like into the combustion chamber 1b. 2 and the inside of the inlet duct 4C can be cleaned, and blockage of the combustion chamber outlet duct 2 and the inlet duct 4C can be prevented.
Further, the unburned portion can be completely burned in the fluid medium collector 4 by the air introduced from the air introduction nozzle 8, and the accumulation of fly ash and the like in the inlet duct 4C can be prevented.

  Thus, in the circulating fluidized bed boiler described above, the inclined inlet duct 4 of the fluid medium recovery unit 4 is connected to the vertical portion 2b of the combustion chamber outlet duct 2 connected to the combustion chamber outlet 1c of the furnace body 1. In addition, since the length of the horizontal portion 2a of the combustion chamber outlet duct 2 is set to the minimum length in terms of structure, the inside of the duct (combustion outlet duct, expansion joint 3) due to a decrease in gas flow rate when the combustion load fluctuates or fuel changes And the accumulation of fly ash and fluid medium S in the inlet duct 4C), and as a result, even if various types of fuels are switched to perform single combustion or mixed combustion, a wide combustion range (high turndown) A stable operation can be performed and a low-load operation is also possible.

  The fluidized medium recovery unit 4 used for the circulating fluidized bed boiler connects the inlet duct 4C to the cylindrical body 4A in a downward inclined posture and is connected to the vertical part 2b of the combustion chamber outlet duct 2 via the expansion joint 3. Therefore, even when an extremely low load operation is performed, the falling of the fluid medium S becomes smooth and obstruction caused by the fluid medium S falling together on the conical portion 4B of the fluid medium collector 4 is avoided. In addition, even when the gas flow rate is low due to low load operation, fly ash and fluid medium S are not deposited on the expansion joint 3, and troubles due to damage to the expansion joint 3 can be avoided.

  Further, in the fluidized medium recovery device 4 of the circulating fluidized bed boiler, the cylindrical body 4A and the inlet duct 4C are integrated, and the cylindrical body 4A and the inlet duct 4C have a water tube panel structure. Since the water pipe (boiler water pipe) and the water pipe (boiler water pipe) of the inlet duct 4C are integrated, the installation work period can be greatly shortened, and the number of water pipe welding processes can be reduced in the field work. The period can be further shortened. .

  In addition, the fluidized medium recovery device 4 of the circulating fluidized bed boiler has an inlet duct 4C connected to the vertical portion 2b of the combustion chamber outlet duct 2 via the expansion joint 3, and the fluidized medium outlet 4b of the fluidized medium recovery device 4. Is connected to the downcomer 5 via the expansion joint 3, and the exhaust gas outlet duct 9 is connected to the exhaust gas outlet 4 a of the fluid medium recovery device 4 via the expansion joint 3. Since the intermediate support structure is self-supporting, the furnace main body 1 having the combustion chamber 1b can also be self-supported by the intermediate support structure by the support column 10, and the support column 10 surrounding the entire circulating fluidized bed boiler becomes unnecessary. It can be simplified and material costs and installation work costs can be greatly reduced, and the construction period can be shortened.

  5 and 6 show a boiler scale in which two fluid medium recovery units 4 according to the embodiment of the present invention are used, and each fluid medium recovery unit 4 is connected to the furnace body 1 via two combustion chamber outlet ducts 2, respectively. 1 shows a large circulating fluidized bed boiler, the circulating fluidized bed boiler being connected to a furnace body 1 having a fluidized bed 1a and a combustion chamber 1b, and connected to the furnace body 1 via a combustion chamber outlet duct 2 and an expansion joint 3, respectively. A basic cylindrical fluid recovery unit 4, two loop seals 6 connected to each fluid recovery unit 4 via downcomers 5, and circulation connecting each loop seal 6 and the furnace body 1. It is composed of a duct 7 for use.

  7 and 8 show a boiler scale in which two fluid medium recovery units 4 according to an embodiment of the present invention are used, and two fluid medium recovery units 4 are connected to the furnace body 1 through one combustion chamber outlet duct 2. The circulating fluidized bed boiler is a furnace body 1 having a fluidized bed 1a and a combustion chamber 1b, and a cylinder connected to the furnace body 1 through a combustion chamber outlet duct 2 and an expansion joint 3. And a loop seal portion 6 connected to the fluid medium collector 4 via a downcomer 5, a circulation duct 7 connecting the loop seal portion 6 and the furnace body 1, and the like. Yes.

The circulating fluidized bed boiler shown in FIGS. 5 to 8 uses two fluidized medium recovery devices 4 according to the boiler scale, and the other configurations are the same as the circulating fluidized bed boiler shown in FIGS. 1 and 2. Therefore, the same parts and members as those in the circulating fluidized bed boiler shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.
The large circulating fluidized bed boiler and the fluidized medium recovery unit 4 used for the large circulating fluidized bed boiler can achieve the same effects as the circulating fluidized bed boiler and the fluidized medium recovery unit 4 shown in FIGS.

  1 is a furnace body, 1a is a fluidized bed, 1b is a combustion chamber, 1c is a combustion chamber outlet, 1d is a return port, 2 is a combustion chamber outlet duct, 2a is a horizontal portion, 2b is a vertical portion, 2c is an inlet, 3 Expansion joint, 4 is a fluid medium collector, 4A is a cylindrical body, 4a is an exhaust gas outlet, 4B is a conical part, 4b is a fluid medium outlet, 4C is an inlet duct, 4C ′ is a vertical part, 4C ″ is an inclined part, 4c Is an exhaust gas inlet, 5 is a downcomer, 6 is a loop seal part, 6a is a partition wall, 6b is an overflow part, 7 is a circulation duct, 8 is an air injection nozzle, 9 is an exhaust gas outlet duct, 10 is a support column, G is Exhaust gas, S is a fluid medium, α is an inclination angle.

Claims (6)

  Connected to one or more combustion chamber outlet ducts, consisting of a horizontal portion that is connected to the combustion chamber outlet of the furnace body having a fluidized bed and a combustion chamber and has a structurally minimum length, and a vertical portion that continues downward from the horizontal portion. The circulating flow that receives the exhaust gas, fluid medium, and fly ash discharged downward from the combustion chamber outlet duct, separates the exhaust gas, fly ash, and fluid medium by gravity acceleration and centrifugal acceleration, and collects the fluid medium from the exhaust gas In the fluid recovery device for a layered boiler, the fluid recovery device is provided at a cylindrical body having an exhaust gas outlet formed at an upper end surface, and at a lower end of the cylindrical body, and gradually decreases in diameter as it goes downward. It consists of a conical part with a fluid medium outlet formed on the end face, and an inlet duct connected to the vertical part of the combustion chamber outlet duct in a downward inclined posture via an expansion joint and connected to the cylindrical body in the tangential direction. Fluidized medium collector circulating fluidized bed boiler, characterized by being configured integrally the cylindrical barrel and the inlet duct.   The fluidized medium recovery device for a circulating fluidized bed boiler according to claim 1, wherein the inclination angle α of the inlet duct is set to 10 ° to 45 °.   The circulation according to claim 1 or 2, wherein the cylindrical body and the inlet duct of the fluid medium recovery unit have a water pipe panel structure, and the water pipe of the cylindrical body and the water pipe of the inlet duct are integrally formed. Fluidized medium recovery unit for fluidized bed boilers.   The size of the outer shape of the fluid medium collector that does not include the inlet duct is set to 2500 mm or less, and the size of the outer shape of the fluid medium collector that includes the inlet duct is set to 3800 mm or less, respectively. The fluidized medium recovery device of the circulating fluidized bed boiler according to claim 2 or 3.   A downcomer is connected to the fluid medium outlet of the fluid medium collector via an expansion joint, and an exhaust gas outlet duct is connected to the exhaust gas outlet of the fluid medium collector via an expansion joint, and the fluid medium collector is supported intermediately by a column. The fluidized medium recovery device for a circulating fluidized bed boiler according to claim 1, wherein the fluidized medium recovery device is a self-supporting structure.   The inlet duct is provided with an air injection nozzle at a position parallel to and close to the bottom surface in the inlet duct, and at least one of air or air, a supplementary fluid medium, a desulfurization agent, and a clinker inhibitor is provided from the air injection nozzle. 6. A fluidized medium recovery device for a circulating fluidized bed boiler according to claim 1, 2, 3, 4, or 5, characterized in that a mixed fluid is introduced.

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