JP2671179B2 - Fluidized bed combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed combustion apparatus such as a fluidized bed boiler for burning waste such as coal and plastics, and more particularly to an upper stage formed above a combustion fluidized bed through a gas dispersion plate. The present invention relates to a fluidized bed combustion apparatus for performing desulfurization and / or dechlorination of flue gas in a fluidized bed.

[0002]

2. Description of the Related Art In a fluidized bed boiler, for example, in a fluidized bed boiler, a fluidized medium such as sand is fluidized by air in a lower combustion fluidized chamber to form a combustion fluidized bed, into which solid fuel such as coal is supplied. The fluid medium is heated by combustion and heated, and the heated fluid medium is brought into 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 on the free board of the combustion fluidized chamber and is introduced into the upper fluidized chamber formed by a gas dispersion plate formed 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.

[0003] When waste such as plastic is used as fuel in the combustion fluidization chamber, hydrogen chloride gas is generated, so that the upper fluidized bed is a dechlorination bed in which desulfurizing agent particles such as limestone are fluidized. Here, the combustion exhaust 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 flue gas containing ash passes through the inside of the gas dispersion tube, ash adheres to the inside of the gas dispersion tube with the progress of operation and becomes blocked due to gas blocking. Could not be fluidized and could not be operated. This deposit is particularly pronounced in the case of coal or waste combustion which produces low melting ash. In addition, at the time of start-up, etc., the temperature of the combustion exhaust gas is low, so that the upper fluidized bed does not reach the entire fluidized state and there is a part that does not partially fluidize, the ash is filled in the gas dispersion pipe in that part, and the whole in the steady state Even when the fluidization speed was reached, the gas could not flow and remained non-fluidized due to resistance due to the ash filling.

The present invention has been made in view of such a problem, and it has been proposed that ash adheres to a gas dispersion pipe of a gas dispersion plate between a lower combustion fluidized bed and an upper fluidized bed for desulfurization or the like. It is an object of the present invention to provide a fluidized bed combustion apparatus capable of eliminating or preventing the filling and simultaneously supplying air such as secondary air for combustion.

[0006]

In order to achieve the above-mentioned object, the present invention has a combustion fluidized chamber in which a combustion fluidized bed is formed below, and a gas having a large number of gas dispersion pipes attached above it. It has an upper flow chamber defined by a dispersion plate and in which an upper fluidized bed is formed, and exhaust gas discharged from the combustion fluidized bed is led to the upper fluidized bed through a number of gas dispersion pipes of the gas dispersion plate, where desulfurization and Alternatively, in a fluidized bed combustion apparatus for performing dechlorination, a fluid supply pipe is attached to a freeboard below the gas distribution plate and across the freeboard in a freeboard of the combustion fluidization chamber so as to be rotatable about its axis, and the fluid supply is performed. A large number of fluid ejection ports are provided on the pipe along the axial direction of the fluid supply pipe at positions that can face the exhaust gas inlets of the many gas dispersion pipes of the gas distribution plate, and the fluid supply pipe is rotated to eject the fluid. The outlet is the exhaust gas inlet of the gas dispersion pipe The position is supplied cleaning fluid of the gas dispersion pipe as a fluid to the fluid supply tube, and a configuration in which air for combustion and or cooling the fluid is supplied in the other position.

[0007]

The position of the fluid ejection port of the flow supply pipe is always located at a position other than facing the exhaust gas inflow port of the gas dispersion pipe, for example, the opening direction of the fluid ejection port is in a direction other than the vertical direction (vertical direction). , More preferably in the downward direction than the horizontal direction,
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 such as the secondary air collides with the combustion exhaust gas rising from below, so that the air and the combustion exhaust gas are mixed well. Moreover, the air is supplied to the freeboard evenly by being supplied from a large number of fluid ejection ports provided in the fluid supply pipe mounted across the freeboard. As a result, the unburned carbon etc. in the freeboard are uniformly burned to improve the combustion efficiency and the two-stage combustion for reducing the nitrogen oxides (NOx) (Burning 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 uniformly and the temperature is adjusted to a temperature suitable for desulfurization or dechlorination of the upper fluidized bed. To be done.

Further, the fluid supply pipe exposed to a high-temperature atmosphere of, for example, 800 to 900 ° C. is kept at a low pipe wall temperature by flowing the air, thereby keeping the life of the pipe long. Then, when the adhesion or the filling of the ash of the gas dispersion pipe is eliminated, the fluid supply pipe is rotated around its axis so that the position of the fluid ejection port of the fluid supply pipe faces the exhaust gas inlet of the gas dispersion pipe. In addition, for example, the opening direction of the fluid ejection port is set to the vertical direction (vertical direction), and instead of the above-mentioned air, a fluid for cleaning the gas dispersion pipe such as steam is flown into the fluid supply pipe, and the fluid ejection pipe is ejected. The cleaning fluid is jetted from the outlet and supplied into the gas dispersion pipe, and the ash attached or filled on the inner wall surface of the gas is removed and cleaned.

Conventionally, air such as secondary air supplied for reducing the NOx and controlling the temperature of the upper fluidized bed is blown out from a large number of nozzles provided along the wall surface of the freeboard of the fluidized combustion chamber. Although it was being supplied, it was not evenly supplied to the center in a large furnace, so the combustion conditions 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 the combustion state and temperature distribution are equalized.

[0010]

Next, an embodiment of the present invention will 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 configuration of a main part 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. FIG.
Numeral 1 is a fluidized bed boiler, 1a is a furnace wall, 10 is a combustion fluid chamber defined on all sides by a furnace wall 1a and defined above by a gas dispersion plate 30 and below by an air dispersion plate (not shown), and 11 is the air A combustion fluidized bed 14 formed by fluidizing a fluid medium 11a made of sand or the like with air for combustion and fluidization supplied from a dispersing plate, and a plurality of boiler tubes 14 vertically arranged in a staggered manner. Reference numeral 12 denotes a free board which is a space above the combustion fluidized bed 11, and reference numeral 13 denotes an auxiliary boiler tube provided in a plurality of stages (three stages in this embodiment) across the free board 12. The auxiliary boiler tubes 13 of each stage are connected to each other by a plate at the top and bottom to form a water-cooled panel structure, and have sufficient strength to support the load of the fluid supply pipe 20 described later.

The gas dispersion plate 30 has a large number of gas dispersion tubes 31.
Are installed at equal intervals in two directions orthogonal to the furnace. As shown in FIG. 2 or FIG. 3, the gas dispersion pipe 31 is vertically fixed to the partition plate 35, and the lower end is fitted to the exhaust gas inlet 32a and the lower end is fitted to the exhaust gas inlet pipe 32. Exhaust gas inflow pipe 32a
And a dispersion pipe main body 33 having a gas inversion cylinder having a gas outlet 34 at an upper end thereof and a gas inversion cylinder having an enlarged diameter.
36 is a water-cooled tube, and 37 is a refractory. A desulfurization chamber 40 as an upper-stage flow chamber is formed at the upper part of the gas dispersion plate 30. Here, the flue gas from the combustion flow chamber supplied from the gas outlets 34 of the gas dispersion pipes 31 into the desulfurization chamber 40 is used. The desulfurizing agent 41a is fluidized to form the desulfurizing bed 41 as an upper fluidized bed. Limestone or dolomite is used as the desulfurizing agent 41a.

Therefore, the fluid supply pipe 20 is arranged across the freeboard 12 in the freeboard 12 of the combustion flow chamber 10 below the gas dispersion plate 30, and 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 fluid supply pipes 20 are attached in parallel in the same arrangement manner. Further, in the direction shown in FIG. 1, they are symmetrically arranged on both sides with respect to the center of the furnace. The fluid supply pipe 20 is supported by the uppermost auxiliary boiler tube 13 via a support member 22 at appropriate locations in the longitudinal direction (three locations in this embodiment).

The support member 22 is fixed to the upper end of the auxiliary boiler tube 13 by a flat plate-like support plate 23 fixed to the upper end of the auxiliary boiler tube 13 and the lower end slit of the support plate 23. Mounted 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 above the upper half of the cutout portion 25a. It is composed of a steady rest 25 that holds and supports the.

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 fluid supply nozzles 21 arranged symmetrically with respect to the vertical center line are attached to the fluid supply pipe 20 in the direction orthogonal to the directions shown in FIGS.
The fluid ejection ports 21a that are the openings are set at positions that can face the exhaust gas inflow ports 32a that are the lower end openings of the gas dispersion pipes 31 located above.

As shown in FIG. 1, one end side of the fluid supply pipe 20 penetrates the furnace wall 1a and extends to the side portion of the furnace wall 1a, and a swivel joint 29 is connected to the pipe end, and this swivel joint 29 is connected. A fluid supply hose 30 communicating with the fluid supply pipe 20 is attached to the. The fluid supply pipe 20 is rotatably connected to the fixed side of the fluid supply hose 30 mounting side by the swivel joint 29.
On the furnace wall 1a, a short pipe nozzle 26 through which the fluid supply pipe 20 is inserted is attached, and a seal box 27 for sealing the gas of the penetrating portion is attached to this. And swivel joint 29 and seal box 27
The fluid supply pipe 20 in between is provided with a hand lever 28 for rotating the fluid supply pipe 20 around its axis. Although not shown, the hand lever 28 is provided with a stopper device that can fix the fluid supply pipe 20 at a predetermined rotation position. On the upstream side of the fluid supply hose 30, 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 configured as described above, coal is burned in the combustion fluidized bed 11 to
1a is heated. Then, the water flowing through the boiler tube 14 is heated by the combustion fluidized bed 11 or the fluid medium particles coming out of the combustion fluidized bed 11 coming into contact with the upper boiler tube 14 to generate steam. Then, the combustion exhaust gas of coal discharged from the combustion fluidized bed 11 rises on the freeboard 12 with ash (ash), unburned carbon, and the like. The flue gas flows together with the ash from the exhaust gas inlet 32a into the exhaust gas inlet pipe 32 of each of the gas dispersion pipes 31 of the gas dispersion plate 30 located above, and rises into the gas inversion cylinder of the upper dispersion pipe main body 33. The gas flows in and 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 a desulfurization bed 41, which is desulfurized by adsorbing sulfur contained in the exhaust gas.
The desulfurized exhaust gas is discharged from an exhaust gas outlet above the desulfurization chamber 40 (not shown). As described above, during the normal operation of the fluidized bed boiler 1, the position of the fluid ejection port 21a of the fluid supply nozzle 21 of the fluid supply pipe 20 is the position indicated by the two-dot chain line as shown in FIGS. 2 and 3 (see FIG. 3). The center line of the two fluid supply nozzles 21 is set to the position B), and the fluid outlet 21a, which is the opening of the fluid supply nozzle 21, does not face the gas inlet 32a of the gas dispersion pipe 31 and is horizontal. It is placed at a position that is oriented downward about 45 degrees from the center line. Secondary air for combustion and cooling is supplied to the fluid supply pipe 20 from the fluid supply hose 30, and the secondary air SA is jetted obliquely downward from the fluid jet port 21a of the fluid supply nozzle 21 to the freeboard 12. Supplied. As a result, the secondary air and the combustion exhaust gas that rises from the lower side to the upper side collide with each other, and good mixing is performed.

Further, this free air SA freeboard 1
The secondary air SA is evenly supplied to the entire freeboard 12 because a large number of fluid supply nozzles 21 are attached to the fluid supply pipes 20 that cross the freeboard 12. As a result, unburned carbon and carbon monoxide are uniformly burned on the freeboard (so-called two-stage burning), and the burning efficiency is improved. Therefore, the removal of nitrogen oxides from the combustion exhaust gas is performed while maintaining high combustion efficiency. Then, the flue gas is uniformly cooled, the temperature distribution of the flue gas is made uniform, and the temperature of the upper desulfurization bed 41 is adjusted to the optimum temperature for desulfurization. Done. In such a two-stage combustion, the air for combustion in the combustion fluidized bed 11 is reduced to keep the oxygen concentration low, and the unburned carbon and carbon monoxide are partially generated to be used for reductive decomposition of nitrogen oxides. Things.

When 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 are cooled by the flow of the secondary air to keep the pipe wall temperature low. , Lifespan is kept long. The auxiliary boiler tube 13 supporting the fluid supply pipe 20 is cooled by flowing water, and the heat retained by the flowing 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, and this ash is generated on 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, the fluid supply pipe 20 is rotated around its axis by the hand lever 28, and the fluid supply nozzle 21 is shown by solid lines in FIGS. 2 and 3. The lower end opening of the gas dispersion pipe 31 is set to a position (the position where the center lines of the two fluid supply nozzles 21 are indicated by A in FIG. 3) and the fluid ejection port 21a that is the opening of the fluid supply nozzle 21 is located above. Exhaust gas inlet 3
Face 2a.

That is, the fluid ejection port 2 of the fluid supply nozzle 21
The axis of 1a and the axis of the exhaust gas inlet 32a of the gas dispersion pipe 31 are made to substantially coincide with each other. Then, the hand lever 28 is fixed to a stopper device (not shown) to prevent the fluid supply pipe 20 from rotating. When the fluid supply pipe 20 is rotated, the fluid supply pipe 20 is supported by the support pipe 24 and is rotated in a state where the left and right positions are held by the steady rest 25. The fluid supply pipe 20 is firmly supported in the freeboard 12 by the action of the steady rest 25 and the support pipe 24 even during operation.

Then, a fluid switching valve (not shown) is operated to supply steam having a predetermined pressure to the fluid supply pipe 20 as a cleaning fluid for the gas dispersion pipe 31 through the fluid supply hose 30 so that the steam is supplied to each fluid supply nozzle 21. The steam ST inflows and the steam ST is jetted upward at a high flow rate from the fluid ejection port 21a, and the exhaust gas inlet 32 of the gas dispersion pipe 31
The gas flows into the inside of a, is reversed inside the gas reversing cylinder inside the gas dispersion pipe 31, and is discharged from the gas outlet 34 into the desulfurization chamber 40. 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 washed away by the steam ST and washed. When this cleaning operation is completed, the fluid supply pipe 20 is rotated to return the fluid supply nozzle 21 to the position shown by the two-dot chain line in FIGS. 2 and 3, and the secondary air is supplied to the fluid supply pipe 20 as described above. To supply.

In order to clean the gas dispersion pipe 31, a plurality of fluid supply pipes 20 are arranged in parallel 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), by installing two fluid supply nozzles 21 from the respective locations of one fluid supply pipe 20, the gas dispersion pipes 31 in two rows can be washed at the same time.
Of course, it is also possible to install three or more fluid supply nozzles 21 so that the gas dispersion pipes 31 in three or more rows can be cleaned simultaneously. Also, of course, one fluid supply pipe 20 and one fluid supply nozzle 21 can be used corresponding to the gas dispersion pipes 31 in one row.

Further, in this embodiment, the fluid supply pipe 20 is provided with the fluid supply nozzle 21, and the tip end opening is provided with the fluid ejection port 2.
Although 1a is used, the fluid ejection port 21a may be provided by directly piercing 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 wastes 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.

[0024]

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 and placed in the gas dispersion pipe. Adhered or filled ash can be removed. For this reason,
It is possible to continuously and smoothly operate the fluidized bed combustion position. In addition, when the gas dispersion pipe is not cleaned, the fluid outlet of the fluid supply pipe is set to a position different from that used for cleaning the gas dispersion pipe to supply air such as secondary air. Since air and the like can be jetted and supplied evenly over the entire surface of the freeboard and can be evenly mixed with combustion exhaust gas, so-called two-stage combustion can reduce nitrogen oxides and maintain combustion efficiency efficiently. You can do it well. Further, since the temperature distribution of the freeboard is also equalized, desulfurization or dechlorination in the upper fluidized bed can be efficiently performed. And the fluid supply pipe can be cooled and protected from high temperature, and the life can be maintained long.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a main part of a fluidized bed boiler as a fluidized bed combustion device according to an embodiment of the present invention.

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

FIG. 3 is a side view taken along line III-III of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid bed boiler 10 Combustion fluidized chamber 11 Combustion fluidized bed 12 Free board 20 Fluid supply pipe 21 Fluid supply nozzle 21a Fluid ejection port ST Steam SA Secondary air 30 Gas dispersion plate 31 Gas dispersion pipe 32 Exhaust gas inlet pipe 32a Exhaust gas inlet 40 Desulfurization chamber (upper fluidized bed) 41 Desulfurization bed (upper fluidized bed)

Claims (1)

(57) [Claims] 1. An upper fluidized chamber having a combustion fluidized chamber below which a combustion fluidized bed is formed, and an upper fluidized bed defined above by a gas dispersion plate having a plurality of gas dispersion pipes mounted thereon. In a fluidized bed combustion apparatus which guides exhaust gas discharged from a combustion fluidized bed through a large number of gas dispersion tubes of the gas dispersion plate to an upper fluidized bed and performs desulfurization and / or dechlorination therein,
A fluid supply pipe is rotatably mounted on the freeboard of the combustion flow chamber, which is below the gas dispersion plate, across the freeboard, and the fluid supply pipe is provided with a fluid ejection port of the fluid supply pipe. A large number are provided in a position that can face the exhaust gas inflow port of the multiple gas dispersion tubes of the gas distribution plate along the axial direction,
The fluid supply pipe is rotated to supply the cleaning fluid for the gas dispersion pipe as a fluid to the fluid supply pipe at the position where the fluid ejection port faces the exhaust gas inflow port of the gas dispersion pipe, and is burned as a fluid at other positions. And / or a fluidized bed combustor characterized by being supplied with cooling air.