JPH0350923B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves supplying coal into a fluidized combustion chamber in which sand flows and combusting it, heating water in a heat transfer tube to generate steam, and after combustion. This relates to a fluidized bed boiler that desulfurizes the gas using a desulfurizing agent and discharges it to the outside.

[Conventional technology]

In recent years, fluidized bed boilers have been developed as boilers with high combustion efficiency and low waste gas pollution. This type of fluidized bed boiler is equipped with three chambers, a storage chamber, a combustion chamber, and a desulfurization chamber, which are separated from the bottom in order from the bottom of the boiler body. The sand stored in the combustion chamber is made to flow by blowing air, and the coal supplied to the combustion chamber is combusted while flowing together with the sand. Steam is generated by heating. Then, the combustion gas is desulfurized with a desulfurizing agent such as limestone in the desulfurization chamber and exhausted, and unburned carbon is captured and burned in the desulfurization chamber.

[Problem that the invention seeks to solve]

However, in conventional fluidized bed boilers, the layer height of the desulfurization agent in the desulfurization chamber remains the same regardless of whether the SO ₂ concentration in the combustion gas is high or low, which varies depending on the sulfur content of the supplied coal. Therefore, when coal with a high sulfur content is used, the amount of SO ₂ in the waste gas may exceed the emission regulation amount. Not only is this wasteful, but there is also the problem that optimal desulfurization conditions cannot be obtained when considering the pressure balance during operation.
Furthermore, if this boiler is operated under normal load and the load is reduced, the amount of combustion gas will decrease and the fluidization height will also be lowered. The problem was that the amount of desulfurizing agent remaining increased, the pressure loss in the desulfurizing bed increased despite the low load, and the operating cost increased due to the increased power of the blower. In addition, even if the load suddenly increases, the amount of combustion gas increases, and the height of the fluidized bed increases, if the height at which the desulfurizing agent is extracted remains constant and does not rise, a large amount of waste limestone will be discharged at once and the exhaust system will There was a problem in that the capacity was exceeded and accidents such as clogging occurred, making treatment troublesome.

[Means for solving problems]

In order to solve these problems, the present invention provides a desulfurizing agent discharge cylinder equipped with an inlet opening to the upper layer of the desulfurizing agent, and attaches a drive device to this to change the opening height of the inlet. A desulfurization agent layer height control device is provided that operates the drive device by detecting at least one of the load, the SO ₂ concentration in the exhaust gas, and the sulfur content in the coal.

[Effect]

During boiler operation, sulfur content in coal and SO ₂ in waste gas
When the concentration and boiler load increase or decrease, the control device detects this and operates the drive device, and the height of the inlet opening of the desulfurizing agent discharge cylinder changes, so that the layer height of the desulfurizing agent is adjusted to the height corresponding to each of the above conditions. It becomes Satoshi.

〔Example〕

FIG. 1 is a longitudinal sectional view showing an embodiment of a fluidized bed boiler according to the present invention. In the figure, the main body 1 of the fluidized bed boiler is formed into a rectangular box shape surrounded on four sides by water-cooled walls 2 in which a plurality of water-cooled pipes (not shown) are buried. An air chamber 7, a storage chamber 8, a combustion chamber 9, and a desulfurization chamber 10 are separated from each other in order from the bottom by partition plates 4, 5, and 6 containing water-cooled pipes 3. Blow pipes 11 and 12 connected to a blower device (not shown) are inserted into the air chamber 7 and the storage chamber 8, respectively, and air is blown into the air chamber 7 and the storage chamber 8.
Coal is supplied to the combustion chamber 9 through a pneumatic coal supply pipe 13 connected to a coal supply hopper (not shown) via a dryer and a pulverizer. Furthermore, a pneumatic limestone transport pipe 14 connected to a limestone supply hopper (not shown) via a crusher is inserted into the desulfurization chamber 10, so that a predetermined amount of desulfurization agent is always kept in the desulfurization chamber 10. Limestone 15 is supplied in such a way that it can be stored. Reference numeral 16 denotes a heat transfer tube installed in a curved manner so as to reciprocate in a staggered manner within the combustion chamber 9, and an air supply tube 17 connected to one end thereof is connected to a circulation pump, and is connected to the other end. The supply pipe 18 is connected to steam-using equipment. In this embodiment, a bypass is provided that connects the air pipe 17 and the supply pipe 18 midway, and serves as a heat transfer pipe of a separately provided exhaust heat utilization boiler. A plurality of distributors 19 are provided on each of the partition plates 4, 5, and 6, and distribute the blown air uniformly and blow it up sequentially into the upper chambers.

Sand 20 as a fluid medium having a diameter of about 1.6 mm is stored in the storage chamber 8.
The same sand 20 is also stored in the combustion chamber 9 at the lower end of the fed coal. Reference numerals 21 and 22 indicate an upcomer and a downcomer for the sand 20, which are provided in communication with the storage chamber 8 and the combustion chamber 9, respectively.The sand 20 is transferred to both chambers 8, 9 manually or by level detection using a sensor. The combustion chamber 9
It is constructed so that the amount of sand 20 inside is kept constant at all times. On the other hand, an exhaust port 23 for discharging combustion gas is provided at the upper end of the desulfurization chamber 10, and is connected to the chimney via the exhaust heat utilization boiler via a duct.

Further, the desulfurization chamber 10 is provided with a desulfurization agent extraction device 24 equipped with a desulfurization agent layer height control device. That is, an outer cylinder 27 connected to a waste limestone storage tank (not shown) through a pipe body 26 is fixed to a bracket 25 fixed to the outer surface of the water cooling wall 2 in an inclined manner. A bearing 28 fixed to the outer surface of the water-cooled wall 2 is slidably fitted into the outer cylinder 27, and an extraction cylinder 29 as a discharge cylinder tilts concentrically with the outer cylinder 27. It is supported freely. Reference numeral 31 denotes a packing holder that prevents the packing 30 from coming off. The extraction cylinder 29 penetrates the water-cooled wall 2 and is inserted into the layer of limestone 15, and the waste limestone 15 that has been altered by desulfurization and collected in the upper layer overflows into the extraction cylinder 29 and forms the outer cylinder 27. It is configured to be discharged to a waste limestone storage tank or the like via the pipe body 26. As a result, the inlet 29 of the extraction tube 29
a is always open at the upper end surface of the limestone 15.
Reference numeral 32 denotes an air cylinder as an extraction cylinder driving device supported by the bracket 25 in parallel with the outer cylinder 27, and the working end of the piston rod 33 is fixed to the projecting piece 34 of the extraction cylinder 29. The head end side port and the rod end side port are connected to the solenoid valve 35 by piping 36, 37.
are connected to each other. On the other hand, the control device 38
is equipped with a controller 39 connected to a solenoid valve 35 and a calculator 40 connected to the controller 39. Detector 4 that emits a signal
1 and SO ₂ in the waste gas discharged from the exhaust port 23
A detector 42 that detects the concentration and emits a signal, and a detector 43 that detects the load of this boiler and emits a signal.
are connected to each other. By doing this, if the amount of sulfur in the coal, the SO ₂ concentration in the waste gas, or the load on the boiler changes, this will be detected by the detectors 41 and 4.
2 and 43 detect each other and issue a signal, the solenoid valve 35 is operated via the computing unit 40 and the controller 39, and the piston rod 33 of the air cylinder 32 and the extraction cylinder 29 move back and forth integrally to open the inlet. 29a
is configured so that its height changes. In this case, the height of the inlet 29a becomes higher as the sulfur content in the coal increases, and as the SO ₂ concentration of the waste gas increases. In addition, the larger the boiler load, the higher it becomes.

The operation of the fluidized bed boiler configured as above will be explained. After supplying coal to the upper layer of sand 21 stored in the combustion chamber 9 and sending air to the air chamber 7 and storage chamber 8, when the coal preheated with a burner etc. is ignited, the combustion air is supplied. Then, the coal burns, and this combustion is promoted by the sand 21 and the coal flowing with the air blown up from the distributor 19, resulting in efficient combustion. This combustion heats the water in the heat exchanger tubes 16 to generate steam, which is supplied to steam-using equipment. On the other hand, the combustion gas enters the desulfurization chamber 10 via the distributor 19, the sulfur content is removed, the gas becomes harmless, and it is discharged from the exhaust port 23, while unburned carbon is captured and combusted in the desulfurization chamber 10. do. The combustion gas discharged from the exhaust port 23 heats the steam headed from the supply pipe 18 to the steam usage equipment when passing through a separately provided boiler, and then is discharged from the chimney.

In addition, among the limestone 15 in the desulfurization chamber 10, the limestone 15 that has changed in quality due to desulfurization and has gathered in an upper layer so as to be higher than the inlet 29a overflows from the inlet 29a, and the extraction cylinder 29, the outer cylinder 27, and the pipe It is discharged to a waste limestone storage tank or the like through the body 26.

In a fluidized bed boiler that operates in this manner, when the coal supplied from the coal supply pipe 13 changes to, for example, coal with a high sulfur content, and the height of the inlet port 29a of the extraction tube is low, combustion gas and limestone 15 may be mixed together. If the contact time is too short, the SO ₂ concentration of the waste gas discharged from the exhaust port 23 increases and tends to exceed the regulation value. However, in this device, when the sulfur content in the coal increases, the detector 41
detects this and moves the piston rod 33 of the air cylinder 32 forward via the calculator 40 and the controller 39, so that the inlet 29a is connected to the chain line 29b in FIG.
As shown in the figure, the amount of limestone 15 discharged decreases and the layer height increases. Therefore, the contact time between the combustion gas and the limestone 15 becomes longer, and the SO ₂ concentration in the waste gas becomes lower. As a result of the experiment, when changing from normal coal to high sulfur coal, the SO ₂ concentration of the waste gas will be 100 ppm if the height of the inlet 29a remains unchanged.
However, by increasing the height of the inlet 29a as described above, even in the case of high sulfur coal, it was possible to reduce the amount to 100 ppm, the same as that for regular coal. Furthermore, if the sulfur content of coal is low, limestone 1
If the height of the layer 5 is too high, more power will be consumed than necessary for desulfurization, and the pressure loss will also become large. Since the height is reduced and the bed height of the limestone 15 is reduced, power consumption is reduced and pressure loss is also reduced. In this device, by providing the detector 42, the SO ₂ concentration in the waste gas can be detected and the layer height of the limestone 15 can be controlled, so that it has the same effect as above.

Furthermore, when the load on the boiler decreases during normal operation, the amount of combustion gas decreases, and the bed height of the limestone 15 becomes too high, resulting in the same wasteful power consumption and pressure loss as described above. By installing this, it detects the load of the boiler and connects the inlet 29.
By lowering a, power consumption and pressure loss are reduced. Additionally, if the load on the boiler suddenly increases during normal operation, the height of the desulfurization bed will increase rapidly, but in this device, the detector 43a detects the load and operates the air cylinder 32, causing the inlet port to 2
Since the height of the limestone 9 is made high, a large amount of limestone 15 is not discharged suddenly, and the discharge system is not clogged with waste limestone.

FIGS. 2a and 2b show a desulfurizing agent discharge cylinder and its driving device as another embodiment of the present invention, and FIG.
is a front view thereof, and FIG. 2b is a longitudinal sectional view thereof. In these figures, on the inner surface of the water cooling wall 2 having the heat insulating material 2a, a guide ring 50 having a U-shaped cross section and a half ring shape is fixed with screws or the like, facing the desulfurization chamber 10. for,
An adjustment plate 51 formed into a circular plate shape is rotatably supported. Further, an outlet 53 is opened on the outer surface of the water cooling wall 2 and is connected to a waste limestone storage tank (not shown) through a duct 52. Entrance 5
4 are communicated with each other by an inclined cylindrical hollow member 55 that penetrates the water cooling wall 2. That is,
The inlet 54, the hollow member 55, and the outlet 53 form a limestone discharge pipe 56 as a desulfurizing agent discharge cylinder that discharges the limestone 15 to the outside of the main body 1. 57 is a water cooling wall 2 corresponding to the center of the adjusting plate 51.
A gland metal is fixed to the outer surface of the gland, and its inner hole is loaded with a packing 59 held down by a packing holder 58. The packing 59 has a drive shaft 60 whose tip is fixed to the adjustment plate 51. It is rotatably supported. A motor shaft 62 of a motor 61 supported on the main body side is connected to the drive shaft 60 by a coupling 63 via a bracket (not shown). Further, the motor 61 is connected to the same control device as in FIG. 1, which is not shown. By doing this, when the motor 61 rotates in response to a command from the control device as described above, the adjustment plate 51 rotates and the height of the inlet port 54 at the eccentric position changes, so that the height at which the limestone 15 is extracted is adjusted. changes.

FIG. 3 further shows another embodiment of the present invention as shown in FIG. 2b.
2 is a vertical cross-sectional view of a desulfurizing agent discharge cylinder and its driving device shown in accordance with FIG. A limestone discharge pipe 71 as a desulfurizing agent discharge cylinder formed in a dogleg shape is connected to the ground metal 70 with an inlet 71a having a bent end facing the upper end surface above the limestone 15. It is rotatably supported, and a duct connected to a waste limestone storage tank or the like is rotatably connected to the outlet 71b. Reference numeral 72 denotes a motor that is drivingly connected to the limestone discharge pipe 71 through gears 73 and 74 and is supported on the main body side. The motor 72 is connected to the same control device as in FIG. 1, which is not shown. By doing this, when the motor 72 rotates in response to a command from the control device as described above, the limestone discharge pipe 7
1 rotates and its inlet 71a swings its head as shown by the solid line and chain line in the figure, so the height of the opening changes and the height at which the limestone 15 is extracted changes.

FIG. 4 further shows another embodiment of the present invention as shown in FIG. 2b.
FIG. 2 is a vertical cross-sectional view of a deflow agent discharge cylinder and its driving device shown corresponding to FIG.
water-cooled wall 2 and a hollow bearing 80 fixed thereto.
A limestone discharge pipe 81 as a desulfurizing agent discharge cylinder bent in an N-shape is rotatably supported on the shaft, and a motor 82 supported on the main body 1 side is connected to a coupling 83 at the protruding end. Drive is connected via. Further, the bearing 80 is provided with an outlet 84 connected to the waste limestone storage tank through a duct, and the engagement portion of the limestone discharge pipe 81 with the bearing 80 has a plurality of holes 81a, 81b. is drilled. The same control device as in FIG. 1, not shown, is connected to the motor 82. By doing so, when the motor 82 is rotated by a command from the control device as described above, the limestone discharge pipe 81 is rotated, the height of its inlet port 81c changes, and the height at which the limestone 15 is extracted changes.

〔Effect of the invention〕

As is clear from the above description, in a fluidized bed boiler according to the present invention, a desulfurizing agent discharge cylinder is provided with an inlet opening to the upper layer of the desulfurizing agent, and a drive is provided to change the opening height of the inlet. The equipment is attached to measure the boiler load, the SO ₂ concentration in the exhaust gas,
By installing a desulfurization agent layer height control device that detects at least one of the sulfur content in coal and activates the drive device, the sulfur content in coal and SO ₂ in waste gas can be reduced.
When the concentration and boiler load increase or decrease, the control device detects this and operates the drive device to change the height of the inlet opening of the desulfurizing agent discharge cylinder to adjust the layer height of the desulfurizing agent to correspond to each of the above conditions. As the sulfur content in the coal increases, the desulfurization rate increases, and the SO ₂ concentration in the waste gas decreases so that it does not exceed the regulated amount. When the SO ₂ concentration decreases or the boiler load decreases, the desulfurization bed becomes lower, which eliminates power consumption for desulfurization, reduces pressure loss, and reduces operating costs. In addition, when the load on the boiler increases, the desulfurization bed becomes higher and waste limestone is not discharged in large amounts suddenly, making it possible to avoid clogging of the discharge system and eliminating processing time, improving operational efficiency. do.

[Brief explanation of drawings]

1 to 4 show an embodiment of a fluidized bed boiler according to the present invention, and FIG. 1 is a longitudinal sectional view thereof, and FIG.
Figures a and b show a desulfurizing agent discharge cylinder and its driving device as other embodiments of the present invention, Figure 2 a is a front view thereof, Figure 2 b is a longitudinal sectional view, Figure 3 and FIG. 4 is a longitudinal sectional view of a desulfurizing agent discharge cylinder and its driving device showing other embodiments of the present invention. 1...Main body, 2...Water cooling wall, 10...Desulfurization chamber,
13... Coal discharge pipe, 14... Limestone transport pipe, 1
5... Limestone, 23... Discharge port, 24... Desulfurizing agent extraction device, 27... Outer cylinder, 29... Extraction tube, 32... Air cylinder, 33... Piston rod, 35... Solenoid valve, 38... ...control device, 39
...Controller, 40...Arithmetic unit, 41, 42, 43
...detector, 50 ... guide ring, 51 ... adjustment plate, 53 ... outflow port, 54 ... inflow port, 55 ...
...Hollow member, 56,71,81...Limestone discharge pipe, 61,72...Motor, 71a, 81c...
Inlet.

Claims (1)

[Claims] 1. A desulfurizing agent discharge cylinder is provided with an inlet that opens to the upper layer of desulfurizing agent inside the main body, and a drive device that changes the opening height of the inlet is attached to this discharge cylinder, and the load of this boiler and , a desulfurization agent layer height control device is provided to operate the drive device by detecting at least one of the SO ₂ concentration in the waste gas discharged from the boiler and the sulfur content in the coal supplied to the boiler. A fluidized bed boiler characterized by: