JPH0743095B2 - Fluidized bed boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention burns a fuel such as coal in a fluidized bed such as sand and absorbs the combustion heat into water in a heat transfer tube to generate steam. The present invention relates to a fluidized bed boiler that desulfurizes the gas after combustion with a desulfurizing agent and discharges it to the outside.Specifically, the temperature of the desulfurization bed can be controlled even when fuels with different properties are used or when the boiler load changes. The present invention relates to an improved fluidized bed boiler that can be adjusted to an optimum desulfurization temperature and can maintain high desulfurization efficiency.

[Prior Art] In recent years, a fluidized bed boiler has been developed as a boiler having high combustion efficiency and less waste gas pollution. This type of fluidized bed boiler has, for example, an air chamber, a fluidized bed combustion chamber, and a fluidized bed desulfurization chamber, which are partitioned in order from the bottom in the boiler body, and always store a predetermined amount in the combustion chamber. The flow medium such as sand is made to flow by blowing air from the air chamber, and the coal supplied to the combustion chamber is burned while flowing along with the sand, and the water passing through the heat transfer tube of the combustion chamber is Steam is generated by being heated by the combustion gas. Then, the combustion gas is desulfurized by a desulfurizing agent such as limestone in the desulfurization chamber and exhausted.

[Problems to be Solved by the Invention] As described above, in a fluidized bed boiler having a fluidized bed combustion section and a fluidized bed desulfurization section separately, generally, combustion temperature conditions in the combustion section and desulfurization temperature conditions in the desulfurization section are used. Since and can be adjusted separately, it has an advantage that the combustion efficiency and the desulfurization efficiency can be increased, but on the other hand, it also has the following problems.

That is, when the fuel to be burned in the combustion section is a fuel with a large amount of volatile matter, or when it is a fuel containing a large amount of fine powder, the proportion of combustion in the freeboard above the fluidized bed in the combustion chamber increases, so the freeboard section In some cases, the temperature of the combustion gas rises and the temperature of the combustion gas entering the desulfurization bed rises, and the desulfurization efficiency drops below the optimum temperature level (750 to 880 ° C) for desulfurization.

When the boiler load changes or the load is operated under different loads, the temperature of the fluidized bed itself, which is in contact with the heat transfer tubes in the combustion section, can be kept constant at, for example, about 950 ° C. In the case of a low load where the upper heat transfer tube is exposed from the fluidized bed in the freeboard section of the engine section, the heat retained by the combustion gas is absorbed by the exposed heat transfer tube and combustion in the freeboard section occurs. The gas temperature is
The temperature drops below 750 ° C, which is below the temperature suitable for desulfurization. On the contrary, when the boiler load is increased from such a state, since the heat transfer tubes are all buried in the fluidized bed, the combustion gas temperature rises and the temperature is almost equal to the fluidized bed temperature, for example, 950 ° C. There is also a problem that the temperature rises to a certain degree, the temperature becomes higher than the temperature suitable for desulfurization, and the desulfurization efficiency decreases.

On the other hand, as a method for adjusting the temperature of the desulfurization bed, for example, as disclosed in Japanese Patent Laid-Open No. 60-101409, a secondary air supply pipe opened on the freeboard of the combustion chamber immediately upstream of the desulfurization section. This can be done by adjusting the flow rate of the secondary air supplied from the, but in order to maintain the combustion efficiency in the combustion bed within the required range, the ratio of the secondary air to the total amount of air has an upper limit value (for example, about 15%). ) In some cases, and in order to reduce NOx, there is no choice but to perform so-called two-stage combustion in which the fluidized bed section and the freeboard section of the combustion chamber combust (that is, as combustion air). The amount of primary air is reduced to partially generate unburned carbon and carbon monoxide in the combustion bed, and this is used for NOx reduction decomposition.)
Since the amount of this secondary air must be in the range of, for example, about 10 to 15%, it may not be possible to change the amount of secondary air in order to adjust the temperature of the desulfurization bed.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and includes an air chamber provided with a primary air supply pipe in the lower portion and an upper side of the air chamber. A combustion chamber provided with a combustion fluidized bed and a heat transfer tube inside, which is separated from the air chamber by a dispersion plate and is supplied with air through the dispersion plate; and a secondary air supply connected to a freeboard of the combustion chamber, In a fluidized bed boiler equipped with a desulfurization chamber having a desulfurization bed for desulfurizing combustion gas generated in the combustion chamber in a downstream upper part of the combustion gas flow of the combustion chamber, a heat transfer pipe is provided in a desulfurization bed upper layer part of the desulfurization chamber. The desulfurizing agent discharge member having an inlet opening in the vicinity of the installation height position of the desulfurization chamber heat transfer pipe is provided in the desulfurization chamber, and the discharge member is provided so that the height of the inlet can be adjusted. The primary air supply pipe and the secondary air supply pipe The desulfurization chamber temperature detector is provided in the desulfurization chamber and the desulfurization agent discharge member is provided with a drive device for adjusting the height of the inlet of the desulfurization agent, and the primary air and the secondary air are provided. A control device for adjusting and driving the desulfurizing agent discharge member drive device based on the detected flow rate value of the flow rate detector or the detected temperature value of the desulfurization bed temperature detector is provided, and the controller controls the inflow port of the desulfurization agent discharge member. A structure in which the desulfurization bed is adjusted to a temperature suitable for desulfurization by changing the height of the desulfurization bed to change the contact area or contact frequency between the desulfurization agent and the desulfurization chamber heat transfer tube by adjusting the height Is.

[Operation] For example, when the volatile content of coal as a fuel to be fed into the boiler becomes high, or when the amount of fine powder becomes large, or when the boiler load is increased, the combustion gas of the freeboard is changed. The temperature rises. When the volatile content of the coal is high, or when the amount of fine powder is large,
The temperature of the desulfurization bed is detected by the temperature detector of the desulfurization chamber, and the signal is sent to the controller of the desulfurizing agent discharge member drive device,
The controller drives the desulfurization agent discharge member driving device, and the height of the inlet of the desulfurization agent discharge member is raised in response to the temperature rise of the desulfurization agent. Also, when the boiler load is increased, the primary air amount and 2
The amount of secondary air is detected by the air flow rate detector, and the signal is sent to the controller of the desulfurizing agent discharge member driving device, and the controller drives the desulfurizing agent discharge member driving device to drive the primary air and the secondary air. The height of the inflow port of the desulfurizing agent discharge member is raised in accordance with the increased amount of air. When the height of the inlet of the desulfurization agent discharge member is increased in this manner, the height of the fluidized bed (desulfurization bed) of the desulfurization agent is increased, and desulfurization of limestone or the like that comes into contact with the heat transfer tube located in the upper layer of the desulfurization agent The amount of the fluidized medium that is the agent increases, that is, the contact area or contact frequency between the desulfurization bed and the heat transfer tubes increases, and the heat transfer amount from the desulfurization bed to the heat transfer tubes increases and the temperature of the desulfurization bed decreases. The temperature is set to a predetermined temperature suitable for desulfurization (for example, 830 ° C). On the contrary, when the combustion gas temperature of the freeboard falls below the temperature suitable for desulfurization due to, for example, a decrease in boiler load, the height of the inlet of the desulfurizing agent discharge member is lowered to increase the height of the desulfurization fluidized bed. The temperature of the desulfurization bed is raised to a temperature suitable for desulfurization because the contact area with the heat transfer tube or the contact frequency is reduced.

Embodiments Embodiments will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a fluidized bed boiler for explaining a fluidized bed boiler according to an embodiment of the present invention.

In the figure, reference numeral 1 is a main body of a fluidized bed boiler, 2 is a boiler furnace body, a dispersion plate 5 is installed at the bottom of the inside of the boiler so as to traverse the inside of the boiler, and an air chamber 7 is partitioned and formed. . A supply pipe 3 for primary air is connected to the air chamber 7. Above the dispersion plate 5 is a combustion chamber (flow chamber) 8, and a large number of heat transfer tubes 16 are installed. In this embodiment,
The heat transfer tubes 16 are installed in three steps in the height direction, and are also installed in a zigzag arrangement in the vertical direction. Reference numeral 13 denotes a fuel (in the present embodiment, granular coal) supply pipe, and a plurality of supply pipes are arranged just above the dispersion plate 5 so as to be uniformly supplied.

A secondary air supply pipe 4 is connected to the freeboard portion 9 above the heat transfer pipe 16. A dispersion plate 6 is installed above the secondary air supply pipe 4 so as to traverse the inside of the boiler furnace body 2, and a desulfurization chamber 10 is formed above the dispersion plate 6. Reference numeral 14 is a pipe for supplying a desulfurizing agent 15 (limestone in this embodiment) such as limestone or dolomite. A large number of heat transfer tubes 17 are installed in the upper layer of the fluidized bed S formed of limestone (desulfurization agent) 15 in the desulfurization chamber 10 so as to cross the desulfurization chamber 10. In this embodiment, the heat transfer tubes 17 are It is installed in one step in the height direction. The fluid flowing through the heat transfer tube 17 is boiler water, superheated steam, or the like. Reference numeral 23 is an outlet provided at the upper end of the desulfurization chamber 10 for discharging the combustion gas after desulfurization, and reference numeral 41
Is a temperature detector that detects the temperature of the fluidized bed S and emits a signal. The primary air supply pipe 3 and the secondary air supply pipe 4 respectively detect flow rate detectors 42 and 43 which detect the amount of air and emit a signal.
Is installed.

Further, the desulfurization chamber 10 is provided with a desulfurizing agent withdrawing device 24 with a desulfurizing agent layer height control device. That is, an outer cylinder 27 connected to a bracket 25 fixed to the outer surface of the boiler furnace body 2 via a pipe body 26 with an unillustrated waste limestone storage tank or the like is fixed in an inclined shape. A bearing cylinder 28 fixed to the outer surface of the boiler furnace body 2 is slidably fitted to the outer cylinder 27, and an extraction cylinder 29 as a discharging member that is inclined concentrically with the outer cylinder 27 is slanted vertically through a packing 30. It is supported to move forward and backward. Reference numeral 31 is a packing retainer for restricting the removal of the packing 30. The extraction cylinder 29 is inserted into the layer of limestone 15 through the boiler furnace body 2 in a state where the opening which is the inflow port 29a of the waste limestone is exposed near the installation height of the heat transfer tube 17. The waste limestone 15 denatured by desulfurization overflows into the extraction cylinder 29 and is discharged to the waste limestone storage tank or the like via the outer cylinder 27 and the pipe body 26. As a result, the inflow port 29a of the extraction cylinder 29 is always open to the upper end surface of the limestone 15 (fluidized bed S). 32 is the outer cylinder
An air cylinder as an extraction cylinder drive device supported by a bracket 25 substantially in parallel with 27, the working end of a piston rod 33 of which is fixed to a projecting piece 34 of the extraction cylinder 29. The port and the rod end side port are connected to the solenoid valve 35 by pipes 36 and 37, respectively. On the other hand, the controller 38 for driving the desulfurizing agent discharge member 38
Is an addition computing unit 44 to which the signals of the primary air flow rate detector 42 and the secondary air flow rate detector 43 are input, and an output signal of the addition computing unit 44 to receive the flow of the extraction cylinder 29 according to the boiler load. It is composed of a function generator 40 for calculating the height of the inlet 29a and a controller 39 to which the output signal of the function generator 40 and the signal of the desulfurization bed temperature detector 41 are input. In this embodiment, an output signal is sent from the controller 39 of the control device 38 to the solenoid valve 35, and the solenoid valve 35 operates the air cylinder 32 of the extraction cylinder drive device.

The height of the inflow port 29a of the extraction cylinder 29 is such that the height of the heat transfer tube 17 is exposed from the fluidized bed S (chain line 29c in FIG. 1) and the heat transfer tube 17 is completely buried in the fluidized bed S. The movable length is within the range of the height (dotted line 29b in FIG. 1). The minimum height position of the inflow port 29a (broken line 29c in Fig. 1) is the required height for maintaining desulfurization efficiency. At this minimum height position, the fluid medium (limestone 15) is the heat transfer tube. The position is such that it does not touch the 17. By doing so, the amount of volatile components and fine powder components in the coal changes, the temperature of the desulfurization bed S changes, or the load of the boiler changes (that is, the amounts of primary air and secondary air change). And the detectors 41, 42 and 43 respectively detect and emit a signal, the signal from the detector 41 via the controller 39, and the signal from the detectors 42 and 43 to the addition calculator. It is sent to the solenoid valve 35 via 44 and the function generator 40, and the solenoid valve 35 operates,
The piston rod 33 of the air cylinder 32 and the extraction cylinder 29 are integrally advanced and retracted so that the height of the inflow port 29a is changed. In this case, the height of the inflow port 29a increases as the combustion gas temperature of the freeboard 9 increases, and as a result, the height of the fluidized bed S of limestone also increases.
The contact frequency between the heat transfer tube 17 and the fluidized bed S increases, or the area where the fluidized bed S contacts the heat transfer tube 17 increases, so that the temperature of the fluidized bed S decreases and the temperature is maintained at a predetermined desulfurization temperature.

In this structure, the fluidized medium made of sand is filled in the combustion chamber 8 above the dispersion plate 5, and the granular coal supplied from the fuel supply pipe 13 is supplied from the primary air supply pipe 3 through the air chamber 7. Combustion is performed by the generated primary air, and this combustion is promoted by the flow of the air blown from the air dispersion plate 15 between the sand and the granular charcoal (forming the fluidized bed G) and efficient combustion. This combustion heats the water in the heat transfer tube 16 to generate steam, which is supplied to the steam using facility. On the other hand, the combustion gas enters the desulfurization chamber 10 through the dispersion plate 6, and fluidizes the limestone in the desulfurization chamber 10 to form a fluidized bed S. In the fluidized bed S, the sulfur content is removed to become a harmless gas. And is discharged from the discharge port 23. The exhaust gas discharged from the discharge port 23 passes through a separately provided waste heat boiler or the like to absorb the heat retained therein, and then is discharged from the chimney.

Further, limestone is continuously supplied from the desulfurization agent supply pipe 14 into the desulfurization chamber 10, and among the limestone 15 in the desulfurization chamber 10, the limestone 15 that has been altered by desulfurization overflows from the inflow port 29a and is withdrawn. It is discharged to a waste limestone storage tank or the like via the cylinder 29, the outer cylinder 27, and the pipe body 26.

Then, in the combustion chamber 8, the installation height of the heat transfer tubes 16 and the installation height of the heat transfer pipes 16 are changed so that the number of buried in the fluidized bed G is changed when the height of the fluidized bed G is changed corresponding to the fluctuation of the boiler load. The filling amount of the fluid medium (sand) is set. For example, when the boiler load becomes maximum, the granular coal supply amount and the primary air supply amount are correspondingly maximized, and the height of the fluidized bed G increases to the level of D in FIG. , All heat transfer tubes 16
Are buried in the fluidized bed G. Further, in the intermediate load state, the granular coal supply amount and the primary air supply amount are correspondingly reduced, the height of the fluidized bed G is lowered to the level E in FIG. 1, and the heat transfer tube 16 The uppermost one is exposed from the fluidized bed G. Furthermore, when the minimum load condition is reached,
The granular coal supply amount and the primary air supply amount are reduced to the minimum amount, and the height of the fluidized bed G is reduced to the level F in FIG. As a result, the heat transfer tubes 18 at the top and middle stages are moved to the fluidized bed G
Therefore, only the lowermost heat transfer tube 18 is buried in the fluidized bed G. As described above, when the height of the fluidized bed G changes in accordance with the load change of the fluidized bed boiler, the number of the heat transfer tubes 16 buried in the fluidized bed G increases and decreases, and the heat transfer area increases and decreases.
Therefore, the total amount of heat transferred from the fluidized bed G to the heat transfer tubes 16 will increase / decrease in accordance with the increase / decrease in the load.
The fluctuation range of the temperature is extremely small. Therefore, the temperature of the fluidized bed G of the combustion chamber 8 is maintained at a substantially constant temperature (for example, 950 ° C.) even when the boiler load changes.

On the other hand, in the process of operating according to the load variation, for example, the boiler load is increased and the height of the fluidized bed G is changed from the level F to the level E or the level E from the level D in FIG. In the case of change, the heat transfer pipe 16 exposed on the freeboard 9 is buried in the fluidized bed G, and therefore the heat of combustion gas held by the heat transfer pipe 16 previously exposed on the freeboard 9 is retained. Free board part 9
The temperature of the combustion gas in the rises and therefore the desulfurization chamber
The temperature of the desulfurization bed S in 10 rises and tries to exceed the temperature range suitable for desulfurization. The relationship of the temperature change of the desulfurization bed S with respect to the fluctuation of the boiler load is as shown in FIG. 2, and the temperature of the desulfurization bed S changes almost in proportion to the boiler load.

Therefore, when the boiler load is increased in this way, the input amounts of the primary air and the secondary air that are increased accordingly (the total amount of the primary air and the secondary air is the exhaust gas discharge of the desulfurization chamber 10). Is operated at a constant excess air ratio in order to limit the carry-out heat amount of the exhaust gas discharged from the outlet 23 and maintain a predetermined boiler efficiency.) Is detected by the flow rate detectors 42, 43, and its detection The signal is input to the addition calculator 44 of the discharge member drive control device 38 to be added, and further, the signal is input to the function generator 40, the signal is input to the controller 39, and the controller 39 causes the solenoid valve 35 to operate. To move the piston rod 33 of the air cylinder 32 forward, the inflow port 29a (or 29c) becomes high as shown by the chain line 29b (or 29a) in FIG. 1, and the height of the desulfurization bed S increases, for example. B (or C) level to A (or B) level As the temperature rises to the bell, the contact frequency or contact area between the desulfurization bed S and the heat transfer tubes 17 increases, the temperature of the desulfurization bed S is lowered, and the temperature suitable for desulfurization is adjusted to, for example, 830 ° C. level.

The temperature of the desulfurization bed S changes substantially in proportion to the height of the inflow port 29a of the waste limestone extraction cylinder 29 as shown in FIG.
If the inlet 29a is raised, the temperature of the desulfurization bed S can be lowered, and if lowered, it can be raised.

Then, the function generator 40 responds to the boiler load according to the relationship shown in FIGS. 2 and 3 so as to maintain the temperature of the desulfurization bed S at a predetermined temperature suitable for desulfurization. The formula of the height of the inflow port 29a of the extraction cylinder 29 is input and set.

Of course, when the boiler load is changed in this way, the temperature itself of the desulfurization bed S is detected by the temperature detector 41, the solenoid valve 35 is operated through the controller 39, and the cylinder 32 is operated. Although it is possible to change the height of the inlet 29a of 29, if the height position of the inlet 29a according to the boiler load is set in advance in the function generator 40 in this way, the heat capacity of the desulfurization bed S A constant temperature control can be performed by compensating for the delay of the temperature change due to the large value (the temperature change of the desulfurization bed S is later than the temperature change of the combustion gas).

On the other hand, the higher the volatile content of the granular charcoal charged into the combustion chamber 8 during operation or the larger the amount of fine powder, the higher the rate of combustion in the freeboard 9 than in the fluidized bed G. In such a case, Causes the temperature of the combustion gas on the freeboard 9 to rise and the temperature of the desulfurization bed S to rise. In this case, the temperature detector 41 of the desulfurization bed S detects the temperature and sends the signal to the controller 39, and the controller 39, via the solenoid valve 35, pulls out the extraction cylinder to a temperature suitable for desulfurization. The height of the inflow port 29a of 29 is increased to increase the height of the fluidized bed S, and the contact frequency or contact area with the heat transfer tube 17 is increased. As a result, the temperature of the desulfurization bed S is lowered and adjusted to a predetermined temperature suitable for desulfurization. Even if some of the unburned carbon is burned in the desulfurization bed S and the temperature of the desulfurization bed S rises, the same operation can be performed to adjust the temperature to a predetermined temperature.

In the above case, the operation is explained when the boiler load is increased, or when the temperature of the desulfurization bed S is increased due to an increase in the volatile content or fine particle content of the granular coal, but the boiler load is reduced. In the case where the volatile content or the fine particle content of the granular coal is lowered and the temperature of the desulfurization bed S is lowered, the temperature of the desulfurization bed S is increased by performing the operation reverse to the above, which is suitable for desulfurization. It is adjusted to a predetermined temperature.

4 (a) and 4 (b) show another embodiment of the desulfurizing agent discharging member and its driving device of the present invention. FIG. 4 (a) is its front view and FIG. 4 (b) is the same longitudinal section. It is a side view. In these figures, on the inner surface of the boiler furnace body 2 having the heat insulating material 2a, a guide ring 50 having a U-shaped cross section and a half ring shape is provided.
The guide ring 50 is rotatably supported on the guide ring 50. The adjustment plate 51 constitutes one of desulfurization material discharge members formed in a circular plate shape. Further, an outlet 53, which is connected to a waste limestone storage tank (not shown) by a duct 52, is opened on the outer surface of the furnace body 2. The outlet 53 and the outer peripheral portion of the adjusting plate 51 are provided. Inlet
A slanting cylindrical hollow member 55 penetrating the furnace body 2
Is communicated by. That is, the inflow port 54, the hollow member 55, and the outflow port 53 form a limestone discharge pipe 56 as a desulfurizing agent discharge member for discharging the limestone 15 to the outside of the main body 1. Reference numeral 57 is a ground metal fixed to the outer surface of the furnace body 2 corresponding to the center of the adjustment plate 51, and the packing 59 held by the packing presser 58 is loaded in the inner hole of the ground metal. The drive shaft 60 having the tip fixed to the adjusting plate 51 is rotatably supported. A motor shaft 62 of a motor 61 supported on the main body side via a bracket (not shown) is connected to the drive shaft 60 by a coupling 63. further,
The motor 61 has the same controller 38 as that shown in FIG.
Are connected. By doing so, when the motor 61 is rotated by a command from the control device 38 as described above, the adjusting plate 51 is rotated and the height of the inflow port 54 at the eccentric position is changed, so that the limestone 15 is extracted. Height, that is, fluidized bed S
In the figure changes between levels A and C, the contact area of the fluidized bed S with the heat transfer tube 17 is changed, and the temperature of the fluidized bed S is adjusted.

FIG. 5 is a vertical cross-sectional view showing another embodiment of the desulfurizing agent discharge member and its driving device of the present invention corresponding to FIG. 4 (b). In this embodiment, the furnace body 2 of the main body 1 is shown. The ground metal 70 is fixed to the outside of the desulfurization chamber 10,
In this ground metal 70, a limestone discharge pipe 71 as a desulfurizing agent discharge member formed in a dogleg shape is rotatably provided with an inlet 71a which is a bent end facing the upper end surface on the limestone 15. A duct connected to a waste limestone storage tank or the like is rotatably joined to the outlet 71b. A motor 72 is drivingly connected to the limestone discharge pipe 71 and gears 73 and 74 and supported on the main body side. The motor 72 is connected to the same control device 38 as that shown in FIG. By doing so, the motor is controlled by the command from the control device 38 as described above.
When 72 rotates, the limestone discharge pipe 71 rotates and its inlet port
Since 71a shakes its head as shown by the solid line and the chain line in the figure, the height of the opening changes, and the extraction height of the limestone 15, that is, the height of the fluidized bed S is between levels A and C in the figure. The temperature of the fluidized bed S is adjusted by the heat transfer tube 17.

FIG. 6 is a longitudinal sectional view showing another embodiment of the desulfurizing agent discharging member and its driving device of the present invention, corresponding to FIG. 4 (b). In this embodiment, the furnace body of the main body 1 is shown. A limestone discharge pipe 81 serving as a desulfurizing agent discharge member bent in a substantially N-shape is rotatably supported by 2 and a hollow bearing 80 fixed thereto, and a protruding end of the limestone discharge pipe 81. A motor 82 supported on the main body 1 side is drivingly connected via a coupling 83. Further, the bearing 80 is provided with an outlet 84 connected to the waste limestone storage tank by a duct, and the engaging portion of the limestone discharge pipe 81 with the bearing 80 has a plurality of holes 81a, 81b. Has been drilled. The motor 82 is connected to the same controller 38 as that shown in FIG. By doing so, when the motor 82 is rotated by a command from the control device 38 as described above, the limestone discharge pipe 81 is rotated and the height of the inflow port 81c is changed, and the extraction height of the limestone 15, that is, , Fluidized bed S
The height of the heat transfer tube 17 is changed between levels A and C in the figure.
The temperature of the fluidized bed S is adjusted by.

In the above embodiments, the heat transfer pipes 17 provided in the desulfurization chamber 10 are provided in one step in the height direction, but if it is desired to adjust the temperature of the desulfurization bed S in a wider range, a plurality of steps may be provided. Of course good things.

[Effects of the Invention] As is clear from the above description, the present invention has the structure as described in the claims, and therefore, the desulfurization bed may be changed due to fluctuations in the amount of volatile components of fuel, fine powder, or boiler load. Even if there is a change in the temperature of the combustion gas flowing in, the temperature of the desulfurization bed can always be automatically adjusted to a temperature suitable for desulfurization, and a fluidized bed boiler with high desulfurization efficiency can be obtained. Then, the combustion fluidized bed and the desulfurization bed can be operated under the respective optimum temperature conditions, and an efficient fluidized bed boiler can be obtained.

Further, according to the present invention, even when the temperature of the combustion gas entering the desulfurization bed from the freeboard rises when the load increases or the fine powder content and volatile content of the fuel increase, the heat retained by the combustion gas is absorbed by the heat transfer tube provided in the desulfurization chamber. Therefore, the boiler efficiency can be improved at the same time when the temperature of the desulfurization bed is adjusted.

Further, even when the secondary air is supplied to the freeboard of the combustion chamber to reduce and remove NOx in the combustion gas, it is not necessary to adjust the temperature of the desulfurization bed with the secondary air, so that the combustion fluidized bed NO by secondary air by maintaining combustion efficiency at required value
It is possible to surely reduce and remove x.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings each show an embodiment of the present invention.
FIG. 2 is a vertical cross-sectional view of a fluidized bed boiler, FIG. 2 is a graph showing the relationship between boiler load and desulfurization bed temperature, FIG. 3 is a graph showing the relationship between waste limestone extraction cylinder height and desulfurization bed temperature, and FIG. ), (B), FIG. 5 and FIG. 6 are drawings showing other embodiments of different desulfurizing agent discharge members and their driving devices. 1 ... Fluidized bed boiler body, 8 ... Combustion chamber, 10 ... Desulfurization chamber, 16 ... Heat transfer tube (combustion part), 17 ... Heat transfer tube (desulfurization part), G ... Fluidized bed (combustion part), S: Fluidized bed (desulfurization section), 29,56,71,81 ... Desulfurizing agent discharge member, 29a, 54,71a, 81c ... Inlet.

Claims (1)

[Claims] 1. An air chamber having a primary air supply pipe at the bottom thereof, and an air chamber provided above the air chamber and separated from the air chamber by a dispersion plate, and air is supplied through the dispersion plate to a combustion fluidized bed inside. And a combustion chamber having a heat transfer tube, a secondary air supply connected to a freeboard of the combustion chamber, and desulfurization of combustion gas generated in the combustion chamber at an upper part downstream of the combustion gas flow in the combustion chamber. In a fluidized bed boiler equipped with a desulfurization chamber having a desulfurization bed, a heat transfer tube is installed in the desulfurization bed upper layer part of the desulfurization room, and an inflow port opening near the installation height position of the desulfurization room heat transfer tube is provided in the desulfurization room. A desulfurizing agent discharge member provided is provided, the height of the inflow port of the discharge member is adjustable, and an air flow rate detector is provided in each of the primary air supply pipe and the secondary air supply pipe, and the desulfurization chamber is also provided. A desulfurization bed temperature detector is installed in the The agent discharge member is provided with a drive device for adjusting the height of its inflow port, and the desulfurization agent is based on the detected flow rate value of the flow rate detector of the primary air and the secondary air or the detected temperature value of the desulfurization bed temperature detector. A control device for adjusting and driving the discharge member drive device is provided, and the height of the desulfurization agent discharge member is adjusted by this control device to change the height of the desulfurization bed to change the desulfurization bed desulfurization agent and the desulfurization chamber heat transfer pipe. A fluidized bed boiler characterized in that a desulfurization bed is adjusted to a temperature suitable for desulfurization by changing a contact area or a contact frequency.