JPH05215310A - Fluidized-bed combustion equipment - Google Patents

Abstract

PURPOSE:To obtain a fluidized-bed combustion equipment capable of solving the adhesion and fullness of ash into the gas dispersing pipe of a gas dispersing plate and capable of also feeding secondary air. CONSTITUTION:A fluid supply pipe 20 is installed to the free board 12 of a combustion fluidizing chamber 10 while crossing the free board 12, a large number of fluid nozzles 21a are mounted at positions being faced to the exhaust- gas inflow ports 32a of a large number of gas dispersing pipes 31 of a gas dispersing plate 30 along the axial direction of the fluid supply pipe 20 in the fluid supply pipe 20, and a fluid for washing a gas dispersing pipe such as steam ST and air (secondary air SA) for combustion and for cooling are supplied being changed over.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed combustor such as a fluidized bed boiler for burning waste such as coal or plastics, and more particularly, an upper stage formed above a combustion fluidized bed via a gas dispersion plate. The present invention relates to a fluidized bed combustor for desulfurizing and / or dechlorinating combustion exhaust gas in a fluidized bed.

[0002]

2. Description of the Related Art As a fluidized bed combustor, for example, in a fluidized bed boiler, a fluidized medium such as sand is fluidized with air in a lower combustion fluidized chamber to form a combusted fluidized bed, into which solid fuel such as coal is supplied. To heat the fluidized medium by heating the fluidized medium to contact with a heat transfer tube such as a boiler tube to apply heat to the heat transfer tube to obtain steam. Then, the combustion exhaust gas discharged from the combustion fluidized bed rises up on the freeboard of the combustion fluidized chamber and is introduced into the upper stage fluidized chamber formed by the gas dispersion plate above the combustion fluidized chamber. Here, for example, desulfurization agent particles such as limestone are fluidized to form a desulfurization bed as an upper fluidized bed, and the combustion exhaust gas is desulfurized here.

When waste such as plastics is used as fuel in the combustion fluidized chamber, hydrogen chloride gas is generated, so that the upper fluidized bed is a dechlorinated bed in which desulfurizing agent particles such as limestone are fluidized. The flue gas is dechlorinated here. The combustion exhaust gas discharged from the combustion fluidized bed flows into the gas dispersion pipes mounted on the gas dispersion plate and is discharged into the upper fluid chamber above, but the combustion exhaust gas contains ash.

[0004]

When the combustion exhaust gas containing ash passes through the inside of the gas dispersion pipe, ash adheres to the inside of the gas dispersion pipe due to the obstruction of the gas dispersion pipe, and the gas cannot pass therethrough. There was a case where the car could not be fluidized and could not be operated. This deposition is particularly pronounced in the case of coal and waste combustion, which produces low melting ash. Also, at startup, etc., the temperature of the combustion exhaust gas is low, so the upper fluidized bed does not reach the entire fluidized state and there is a portion that does not partially fluidize, and the gas dispersion pipe at that portion is filled with ash, and the entire steady state is Even when the fluidization rate was reached, the gas did not flow and remained unfluidized due to the resistance due to the ash filling.

The present invention has been made in view of the above problems, and ashes and ash adhere to the inside of the gas dispersion pipe of the gas dispersion plate between the lower combustion fluidized bed and the upper fluidized bed for desulfurization or the like. It is an object of the present invention to provide a fluidized bed combustion apparatus which can eliminate or prevent filling and can also supply air such as secondary air for combustion.

[0006]

In order to achieve the above-mentioned object, the present invention has a combustion fluid chamber in which a combustion fluidized bed is formed below, and a gas in which a large number of gas dispersion pipes are attached above it. It has an upper flow chamber defined by a dispersion plate to form an upper fluidized bed, and guides the exhaust gas discharged from the combustion fluidized bed to the upper fluidized bed through a number of gas dispersion pipes of the gas dispersion plate, where desulfurization and In addition, in a fluidized bed combustion device that performs dechlorination,
A fluid supply pipe is attached to the freeboard of the combustion flow chamber below the gas distribution plate across the freeboard, and a fluid jet port is provided in the fluid supply pipe along the axial direction of the fluid supply pipe. A large number of the gas dispersion pipes are provided at positions facing the exhaust gas inflow port, and a fluid for cleaning the gas dispersion pipe and air for combustion and / or cooling are switched and supplied as fluids to the fluid supply pipe. And

[0007]

In normal operation, air such as secondary air is caused to flow through the fluid supply pipe and is jetted from the fluid jet port to the freeboard to be supplied. The air is supplied from a plurality of fluid ejection ports provided in a fluid supply pipe mounted across the freeboard, so that the air is evenly supplied to the freeboard and is mixed well with the combustion exhaust gas rising from below. For this reason, the unburned carbon and the like are uniformly burned on the freeboard to improve the combustion efficiency, and the two-stage combustion for reducing the nitrogen oxides (NO _x ) (Combusting combustion carbon, etc.) is effectively performed, and the combustion exhaust gas is also cooled uniformly, so that the temperature control of the upper fluidized bed is performed evenly and the temperature is suitable for desulfurization or dechlorination of the upper fluidized bed. Adjusted.

Further, the fluid supply pipe exposed to a high temperature atmosphere of 800 to 900 ° C., for example, is kept at a low pipe wall temperature by the flow of the air, and the life of the pipe is kept long. When ash adheres to or fills the gas dispersion pipe during operation, the fluid supplied to the fluid supply pipe is switched to supply the gas dispersion pipe cleaning fluid such as steam to the fluid supply pipe. The cleaning fluid is ejected from the outlet and supplied into the gas dispersion pipe, and the ash attached or filled on the inner wall surface of the gas dispersion pipe is removed for cleaning.

Conventionally, air such as secondary air supplied for the above-mentioned two-stage combustion for NO _x reduction and temperature control of the upper fluidized bed is provided along the wall surface of the freeboard of the fluidized combustion chamber. It was supplied from a large number of nozzles,
In the case of a large-scale furnace, it was not evenly supplied to the center, so the combustion condition of the two-stage combustion in the freeboard and the uneven temperature distribution of the freeboard and the upper fluidized bed occurred. However, in the present invention, air such as secondary air is evenly supplied to the freeboard from the fluid supply nozzles attached to a large number of fluid supply pipes that cross the freeboard, and mixing with the combustion exhaust gas is performed well, so that the combustion situation And temperature distribution are equalized.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. Each of the drawings shows an embodiment of the present invention, FIG. 1 is a vertical cross-sectional view showing a main part configuration of a fluidized bed boiler as a fluidized bed combustion device, FIG. 2 is an enlarged view of a II portion of FIG. 1, and FIG. FIG. 3 is a side view taken along the line III-III of FIG. Figure 1
In the figure, 1 is a fluidized bed boiler, 1 a is a furnace wall, 10 is a combustion fluid chamber defined by a gas dispersion plate 30 on the four sides and an air dispersion plate not shown on the lower side, surrounded by the furnace walls 1 a, and 11 is the air. A combustion fluidized bed formed by fluidizing a fluidized medium 11a made of sand or the like with combustion- and fluidizing air supplied from a dispersion plate, and 14 is a boiler tube arranged in a zigzag pattern in a plurality of stages in the vertical direction. , 12 is a freeboard which is a space above the combustion fluidized bed 11, and 13 is an auxiliary boiler tube which is provided in a plurality of stages (three stages in this embodiment) in the vertical direction across the freeboard 12. The auxiliary boiler tubes 13 at the respective stages have a water-cooled panel structure in which the upper and lower sides are connected by a plate body, and have sufficient strength to support the load of a fluid supply pipe 20 described later.

The gas dispersion plate 30 has a large number of gas dispersion pipes 31.
Are mounted at equal intervals in two orthogonal directions across the furnace. As shown in FIG. 2 or 3, the gas dispersion pipe 31 is vertically fixed to the partition plate 35, and the exhaust gas inflow pipe 32 having the lower end opening as the exhaust gas inflow port 32a and the lower end portion is fitted in the exhaust gas inflow pipe 32. Supported by the exhaust gas inflow pipe 32a
And a dispersion pipe main body 33 having a gas reversal cylinder having an expanded diameter at the upper portion thereof.
Reference numeral 36 is a water cooling pipe, and 37 is a refractory material. A desulfurization chamber 40 as an upper flow chamber is formed in the upper part of the gas dispersion plate 30, and here, by the combustion exhaust gas from the combustion fluid chamber supplied from the gas outlets 34 of the plurality of gas dispersion pipes 31 into the desulfurization chamber 40. The desulfurization agent 41a is fluidized to form the desulfurization bed 41 as the upper fluidized bed. Limestone, dolomite, or the like is used as the desulfurizing agent 41a.

A fluid supply pipe 20 is arranged across the freeboard 12 and attached to the freeboard 12 of the combustion flow chamber 10 below the gas dispersion plate 30.
In the case of the present embodiment, the fluid supply pipe 20 is located at the center of the mounting row of the adjacent gas dispersion pipes 31 as shown in FIG. Although not shown, a plurality of the fluid supply pipes 20 are attached in parallel in the same arrangement.
In the direction shown in FIG. 1, they are symmetrically arranged on both sides of the center of the furnace. The fluid supply pipe 20 is supported by the uppermost auxiliary boiler tube 13 at appropriate places (three places in this embodiment) in the longitudinal direction via support members 22.

The support member 22 has a flat plate-like support plate 23 fixed to the upper end of the supplemental rib boiler tube 13 so as to extend in the axial direction thereof, and the upper end of the support plate 23 is inserted and fixed to a slit portion at the lower end. Attached support tube 24, and
While the fluid supply pipe 20 is placed on the support pipe 24, both hook portions 25b at the lower end are engaged with both ends of the support pipe 24, and the fluid supply pipe 20 is slightly upper half in the cutout portion 25a inside. It is composed of a steady rest 25 that holds and supports the above-mentioned.

As shown in FIGS. 1 and 2, each of the fluid supply pipes 20 has a plurality of gas dispersion pipes 31 attached to the gas dispersion plate 30 along the axial direction of the pipe 20 in one direction of the furnace. Of the exhaust gas inflow port 32a of FIG.
As shown in FIG. 2, two fluids are disposed symmetrically with respect to the vertical center line in the fluid supply pipe 20 in the direction orthogonal to the directions shown in FIGS. A supply nozzle 21 is attached. The fluid ejection ports 21a, which are the upper end openings thereof, are set at positions facing the exhaust gas inflow ports 32a, which are the lower end openings of the gas dispersion pipes 31 located above, respectively.

As shown in FIG. 1, one end side of the fluid supply pipe 20 extends through the furnace wall 1a to the side portion of the furnace wall 1a, and has a fluid supply hose 28 communicating with the fluid supply pipe 20 at the pipe end.
Is installed. Further, a short pipe nozzle 26 through which the fluid supply pipe 20 is inserted is attached to the furnace wall 1a, and a seal box 27 for performing gas sealing of the penetrating portion is attached to this. On the upstream side of the fluid supply hose 28, a switching valve (not shown) for alternately switching the supply of secondary air and steam as a fluid for cleaning the gas dispersion pipe is attached.

In the fluidized bed boiler 1 constructed as described above, coal is burned in the combustion fluidized bed 11 and the fluidized medium 1
1a is heated. Then, when the combustion fluidized bed 11 or the fluid medium particles jumping out of the combustion fluidized bed 11 come into contact with the upper boiler tube 14, the water flowing through the boiler tube 14 is heated and steam is generated. Then, the combustion exhaust gas of coal discharged from the combustion fluidized bed 11 moves up the freeboard 12 along with ash (ash) unburned carbon and the like. The combustion exhaust gas flows into the exhaust gas inflow pipe 32 of each gas dispersion pipe 31 of the gas dispersion plate 30 located in the upper part together with the ash from the exhaust gas inlet 32a and rises to enter the gas reversal cylinder of the upper dispersion pipe body 33. It flows in, reverses, and is discharged from the gas outlet 34 into the desulfurization chamber 40.

In the desulfurization chamber 40, the desulfurization agent 41a is fluidized by the combustion exhaust gas to form the desulfurization bed 41, and the sulfur content contained in the exhaust gas is adsorbed to be desulfurized.
The desulfurized exhaust gas is discharged from an exhaust gas discharge port above the desulfurization chamber 40 (not shown). As described above, during normal operation of the fluidized bed boiler 1, secondary air for combustion and cooling is supplied from the fluid supply hose 28 to the fluid supply pipe 20, and the secondary air SA of the fluid supply nozzle 21. It is jetted and supplied upward from the fluid jet port 21a to the freeboard 12.

The supply of the secondary air SA to the freeboard 12 is carried out from a plurality of fluid supply nozzles 21 attached to the fluid supply pipe 20 which crosses the freeboard 12, so that the secondary air SA is supplied to the freeboard 12. It is washed evenly throughout. As a result, the secondary air SA is evenly supplied to the combustion exhaust gas rising from the lower side to the upper side for good mixing, and the freeboard burns unburned carbon and carbon monoxide (so-called 2 Stage combustion) is performed well and combustion efficiency is improved. Therefore, the removal of nitrogen oxides from the combustion exhaust gas is performed while maintaining good combustion efficiency. Then, the flue gas is satisfactorily cooled, the temperature distribution of the flue gas is made uniform, and the temperature of the upper desulfurization bed 41 is adjusted to an optimum temperature for desulfurization. Done. In such a two-stage combustion, the combustion air in the combustion fluidized bed 11 is reduced to keep the oxygen concentration low and a part of the unburned carbon or carbon monoxide is generated and used for the reductive decomposition of nitrogen oxides. It is a thing.

While the fluidized bed boiler 1 is in operation, the fluid supply pipe 20 and the fluid supply nozzle 21 are exposed to a high temperature atmosphere, but the secondary wall air is cooled and the pipe wall temperature is kept low. , Lifespan is kept long. The auxiliary boiler tube 13 that supports the fluid supply pipe 20 is cooled by passing water, and the heat of passing water is also recovered. Then, during operation of the fluidized bed boiler 1, ash generated from the combustion fluidized bed 11 passes through the gas dispersion pipe 31 together with the combustion exhaust gas,
This ash forms the inner wall of the gas inflow pipe 32a and the dispersion pipe body 33.
When it adheres to the inner wall of the gas reversing cylinder, or when it is full, a fluid switching valve (not shown) is actuated to pass through the fluid supply hose 28 and to the fluid supply pipe 20 at a predetermined pressure as a cleaning fluid for the gas dispersion pipe 31. Steam is supplied.

Then, steam flows into each of the fluid supply nozzles 21 and the steam S is discharged from the fluid ejection ports 21a.
T is jetted upward at a high flow rate and flows into the exhaust gas inlet 32a of the gas dispersion pipe 31, reverses the inside of the gas reversal cylinder inside the gas dispersion pipe 31, and is discharged from the gas outlet 34 into the desulfurization chamber 40. It As a result, the ash adhering to or filling the exhaust gas inlet 32a and the inner wall surface of the gas reversing cylinder is steam S.
It is washed away by T. The fluid supply pipe 20 is firmly fixed and supported in the freeboard 12 by the action of the steady rest 25 and the support pipe 24 even during operation. When this cleaning operation is completed, the fluid switching valve is operated to supply the secondary air to the fluid supply pipe 20 as described above.

In order to clean the gas dispersion pipe 31 as described above, a plurality of fluid supply pipes 20 are arranged in parallel with each other in the furnace so that ash adheres or fills in the gas dispersion pipe 31 to clean the gas at a portion requiring cleaning. This can be done for the row of dispersion tubes and can be done without any trouble during operation. In this embodiment, FIG.
As shown in (2), two fluid supply nozzles 21 are attached from each position of one fluid supply pipe 20, so that the gas dispersion pipes 31 in two rows can be cleaned at the same time.
Of course, three or more fluid supply nozzles 21 may be attached so that the gas dispersion pipes 31 in three or more rows can be cleaned simultaneously. Further, of course, one fluid supply pipe 20 and one fluid supply nozzle 21 may be provided corresponding to the gas dispersion pipes 31 in one row.

Further, in this embodiment, the fluid supply pipe 20 is provided with a fluid supply nozzle 21, and the tip opening is provided at the fluid ejection port 2.
However, the fluid ejection port 21a may be provided by directly boring the fluid supply pipe 20. The present invention, as a fluidized bed combustion device, in addition to a fluidized bed boiler using coal fuel,
It is also suitably used for fluidized bed boilers, fluidized bed incinerators and the like that use waste such as plastics as fuel. In this case, the upper fluidized bed is a dechlorination bed. As the cleaning fluid for the gas dispersion pipe 31, compressed air or the like can be used in addition to steam.

[0023]

As is apparent from the above description, according to the present invention, the inside of the gas dispersion pipe of the gas dispersion plate between the lower combustion flow chamber and the upper flow chamber is effectively cleaned to form the gas dispersion pipe inside. Adhered or full ash can be removed. For this reason,
The fluidized bed combustion apparatus can be continuously and smoothly operated. In addition, when the gas dispersion pipe is not cleaned, air such as secondary air is supplied from a number of fluid outlets, and the secondary air is evenly jetted and supplied to the entire surface of the freeboard to mix it uniformly with the combustion exhaust gas. Therefore, the so-called two-stage combustion can efficiently reduce the nitrogen oxides and maintain the combustion efficiency. Further, since the temperature distribution of the freeboard is equalized, desulfurization or dechlorination in the upper fluidized bed can be efficiently performed. Further, the fluid supply pipe can be cooled and protected from high temperature, and the life can be maintained for a long time.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a main configuration of a fluidized bed boiler as a fluidized bed combustion apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a part II in FIG.

FIG. 3 is a side view taken along line III-III of FIG.

[Explanation of symbols]

 1 Fluidized Bed Boiler 10 Combustion Fluidized Chamber 11 Combustion Fluidized Bed 12 Freeboard 20 Fluid Supply Pipe 21 Fluid Supply Nozzle 21a Fluid Jet Outlet ST Steam SA Secondary Air 30 Gas Dispersion Plate 31 Gas Dispersion Pipe 32 Exhaust Gas Inflow Pipe 32a Exhaust Gas Inlet 40 Desulfurization room (upper fluidized bed) 41 Desulfurization bed (upper fluidized bed)

Claims (1)

[Claims] 1. An upper flow chamber having a combustion fluid chamber in which a combustion fluidized bed is formed below, and an upper fluidized bed formed by a gas dispersion plate having a number of gas dispersion pipes attached above it. In the fluidized bed combustor in which the exhaust gas discharged from the combustion fluidized bed is introduced into the upper fluidized bed through a number of gas dispersion tubes of the gas dispersion plate and desulfurized and / or dechlorinated,
A fluid supply pipe is attached to the freeboard of the combustion flow chamber below the gas distribution plate across the freeboard, and a fluid jet port is provided in the fluid supply pipe along the axial direction of the fluid supply pipe. A large number of the gas dispersion pipes are provided at positions facing the exhaust gas inflow port, and a fluid for cleaning the gas dispersion pipe and air for combustion and / or cooling are switched and supplied as fluids to the fluid supply pipe. The fluidized bed combustor characterized in that