JP3552356B2 - Separation ash transport device of pressurized fluidized bed boiler - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for transporting separated ash of a pressurized fluidized-bed boiler.
[0002]
[Prior art]
An example of a pressurized fluidized-bed boiler will be described with reference to FIG. 2. A fluidized-bed boiler 2 is provided in a pressure vessel 1 in which the inside is in a pressurized atmosphere. A plurality of diffuser tubes 3 extending in the left-right direction are arranged in front and rear, and the diffuser tubes 3 take in the pressurized air 4 in the pressure vessel 1 from the lower intake port 3a and jet it upward. ing.
[0003]
A fuel supply pipe 5 for supplying a fuel such as coal particles or coal slurry is disposed above the diffuser pipe 3 and a bed in which a desulfurizing material such as limestone, sand and the like for forming the fluidized bed 6 are mixed. The material 7 is supplied, and the pressurized air 4 supplied from the compressor 8 into the pressure vessel 1 is supplied from the lower intake port 3a to the diffuser 3 and injected upward to form the fluidized bed 6, The fuel supplied from the fuel supply pipe 5 is stirred in the fluidized bed 6 and efficiently burned, so that the water is heated by the heat transfer pipe 9 disposed in the formation portion of the fluidized bed 6 to generate steam. Is to be generated.
[0004]
Further, the ash generated by the combustion and part of the bed material 7 fall from the space between the air diffusers 3 to the ash hopper 10 provided on the lower side, and pass through the lower ash extraction pipe 11 to the lower part. To be taken out.
[0005]
Above the fluidized-bed boiler 2, a plurality of (for example, seven) cyclones 14 through which a high-temperature and high-pressure exhaust gas 12 after heating water in the heat transfer tube 9 is guided through a branch duct 13 are arranged. The ash in the exhaust gas 12 is separated. The exhaust gas 12 from which the ash is separated by the cyclone 14 is supplied to a gas turbine 16 provided outside the pressure vessel 1 via an exhaust gas pipe 15 to drive the gas turbine 16, and the gas turbine 16 controls the compressor 8 described above. While driving, the gas turbine generator 17 is driven by the surplus power.
[0006]
The cyclone 14 is connected to a separation ash transport device 19 for transporting the separation ash 18 separated by the cyclone 14 to the outside of the pressure vessel 1.
[0007]
The separated ash transport device 19 includes ash transport tubes 20a, 20b, 20c, 20d, 20e, and 20f each having one end connected to each cyclone 14, and each of the ash transport tubes 20a to 20f is a pressure vessel. The ash cooler 21 is formed by bending the ash cooler 21 to cool the separated ash 18 with the pressurized air 4. Further, the ash transport pipes 20 a to 20 f after the ash cooler 21 is formed are: It is led out of the pressure vessel 1 and is connected to one end of one connecting pipe 22.
[0008]
The other end of the connection pipe 22 is connected to a decompression tank 24 via a decompression orifice 23, and the decompression tank 24 is connected to a downstream ash treatment device 25.
[0009]
Since the pressure inside the cyclone 14 is high and the pressure inside the decompression tank 24 is low (atmospheric pressure), when the pressure is released to the decompression tank 24 through the decompression orifice 23, the pressure difference causes The separated ash 18 separated at 14 is sucked by the ash transport pipes 20 a to 20 f together with the exhaust gas 12 in the cyclone 14 and discharged to the decompression tank 24.
[0010]
In the separated ash transport device 19 of the pressurized fluidized bed boiler, since each of the ash transport pipes 20a to 20f has a small diameter and forms a bent ash cooler 21, the ash flow becomes unstable. Flow rate of the exhaust gas 12 when the pressurized fluidized bed boiler is started or stopped, or when the load changes, because the gas flow balance of the ash transport pipes 20a to 20f connected to the connecting pipe 22 is easily lost. When the amount of the separated ash 18 in the exhaust gas 12 fluctuates, one or more of the ash transport pipes 20a to 20f are blocked by the separated ash 18.
[0011]
When one of the ash transport pipes 20a to 20f is closed, the temperature of the ash transport pipes 20a to 20f decreases because the high-temperature separated ash 18 does not flow in the ash transport pipes 20a to 20f. And thermometers 26 and 27 are installed in the ash transport pipes 20a to 20f outside the pressure vessel 1, and when the detected temperatures of the thermometers 26 and 27 decrease, the ash transport pipes 20a to 20f are closed. Is to be detected.
[0012]
Conventionally, when the above-described ash transport pipes 20a to 20f are blocked by the separated ash 18, the clogged ash transport pipes 20a to 20f are separated outside the pressure vessel 1, and the separated ash transport pipes 20a to 20f are supplied with high-pressure gas. Is blown or vacuum sucked to release the blockage.
[0013]
However, in the separated ash transport device of the pressurized fluidized bed boiler, when the ash transport pipes 20a to 20f are blocked, the blockage is detected and the ash transport pipes 20a to 20f are cut off, and high-pressure gas is blown or vacuumed. Since the blockage is released by suction, the blockage cannot be released while the pressurized fluidized bed boiler is operating, and it is necessary to stop the operation of the pressurized fluidized bed boiler due to the blockage. There was an operational problem.
[0014]
For this reason, in recent years, each of the ash transport pipes 20a to 20f is independently connected to the decompression tank 24 as shown in FIG. A configuration in which a decompression orifice 28 is provided in each of the ash transport pipes 20a to 20f has been considered.
[0015]
[Problems to be solved by the invention]
However, also in the separated ash transport device of the pressurized fluidized bed boiler as shown in FIG. 3, the ash transport pipes 20a to 20f form the bent ash cooler 21 and the ash flow becomes unstable. However, since there still remains a problem that the pressure of each of the ash transport pipes 20a to 20f tends to fluctuate, the flow rate of the exhaust gas 12 and the separated ash in the exhaust gas 12 when the pressurized fluidized bed boiler is started or stopped, or when the load changes, etc. There still remains a problem that the ash transport pipes 20a to 20f are blocked by the separated ash 18 when the amount of 18 fluctuates.
[0016]
The present invention has been made in view of the above circumstances, and provides a separated ash transport device for a pressurized fluidized-bed boiler that prevents an ash transport pipe from being blocked by a separated ash of a cyclone. The purpose is.
[0017]
[Means for Solving the Problems]
The present invention relates to a plurality of cyclones connected to a fluidized bed boiler installed in a pressure vessel to separate ash in exhaust gas, and an ash cooler connected to each cyclone and separated ash separated by the cyclone. An ash transportation pipe for a pressurized fluidized-bed boiler comprising an ash transportation pipe leading to a decompression tank outside a pressure vessel via a decompression orifice arranged at a position close to the decompression tank of each of the ash transportation pipes, A bypass pipe that bypasses the decompression orifice and connects each ash transport pipe to the decompression tank, an on-off valve provided in each bypass pipe, and a pressure detector disposed upstream of the on-off valve in each of the bypass pipes; A controller that opens a corresponding on-off valve when the pressure detection signal of the pressure detector is equal to or less than a set value and closes the corresponding on-off valve when the pressure detection signal is equal to or greater than the set value. Layer boiler Hanarehai transport device, which relates to.
[0018]
The present invention also relates to an apparatus for transporting separated ash of a pressurized fluidized-bed boiler, wherein a pressurized gas source is connected to a bypass pipe via an on-off valve for blowing.
[0019]
In the present invention, when the flow rate of the exhaust gas and the amount of the separated ash in the exhaust gas fluctuate when the pressurized fluidized bed boiler is started or stopped, or due to a load change, the flow of the separated ash becomes unstable, so that the ash transport pipe is formed. Attempts to block with separated ash.
[0020]
When such a state occurs, the pressure in the ash transport pipe at the pressure reducer inlet decreases due to a decrease in the flow rate of the exhaust gas flowing through the ash transport pipe, and this pressure decrease is immediately detected by the pressure detector, and the pressure When the pressure detection signal of the detector falls below the set value set in the controller, the controller immediately performs control to open the on-off valve, and when the on-off valve is opened, the exhaust gas from the ash transport pipe has a decompression orifice. Instead, the flow path resistance will be opened to the decompression tank through a small bypass pipe, so that the exhaust gas flow rate of the ash transport pipe, which is likely to be blocked, is rapidly increased, and the problem of blockage is prevented beforehand. You.
[0021]
Further, in the present invention, since the pressurized gas source is connected to the bypass pipe via the blow on-off valve, the on-off valve is closed in the event that the ash transport pipe is closed. In this state, the blow valve is opened for a predetermined time and the high-pressure gas from the pressurized gas source is blown into the ash transport pipe for backwashing, thereby disintegrating the ash in the portion where the clogging has occurred. When the pressurized fluidized-bed boiler is operated, the clogging can be released by causing the exhaust gas to flow to discharge the separated ash to the decompression tank.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows an example of an embodiment of the present invention. In FIG. 1, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0024]
As shown in FIG. 1, one end is connected to each of a plurality of cyclones 14 (for example, seven) provided in the fluidized bed boiler 2 in the pressure vessel 1 to form an ash cooler 21 and lead out of the pressure vessel 1. The other end of each of the ash transport pipes 20a to 20f is connected to the vacuum tank 24 via the shutoff valve 33a and the vacuum orifice 28.
[0025]
Further, a bypass pipe 29 for connecting each of the ash transport pipes 20a to 20f to the decompression tank 24 while bypassing each of the pressure reducing orifices 28 is provided, and an opening / closing valve 30 is provided for each of the bypass pipes 29.
[0026]
A pressure detector 31 is disposed upstream of each of the on-off valves 30 of each of the bypass pipes 29. When the pressure detection signal of the pressure detector 31 is equal to or less than a set value, the on-off valve 30 is opened, and the pressure detection signal is set. A controller 32 for closing the on-off valve 30 when the value is equal to or more than the value is provided. The set value set in the controller 32 is determined in a test operation stage of the pressurized fluidized-bed boiler in such a manner that the relationship between the clogging of the ash transport pipes 20a to 20f by the separated ash 18 and the pressure is determined. Is set in such a manner that the problem is easily caused.
[0027]
In addition, a pressurized gas source 34 capable of supplying an inert gas such as nitrogen gas or other gas is connected to each of the bypass pipes 29 via a blow on-off valve 33 to constitute a blockage release device 35. .
[0028]
Next, the operation of an example of the above embodiment will be described.
[0029]
During normal operation of the pressurized fluidized-bed boiler, the on-off valve 30 for blowing is closed, and the pressure of each of the ash transport pipes 20a to 20f is opened to the decompression tank 24 via the decompression orifice 28, so that each The separated ash 18 separated by the cyclone 14 is sucked by each of the ash transport pipes 20a to 20f and discharged to the decompression tank 24. The pressure detection signal detected by the pressure detector 31 in this state is maintained at a pressure sufficiently higher than the set value set in the controller 32.
[0030]
From this state, when the flow rate of the exhaust gas 12 and the amount of the separated ash 18 in the exhaust gas 12 fluctuate when the pressurized fluidized bed boiler is started or stopped, or due to a load change, the flow of the separated ash 18 becomes unstable. The ash transport pipes 20 a to 20 f tend to be blocked by the separated ash 18.
[0031]
When such a state occurs, the flow rate of the exhaust gas 12 flowing through the ash transport pipes 20a to 20f decreases, so that the pressure in the ash transport pipes 20a to 20f decreases. This decrease in pressure is immediately detected by the pressure detector 31 provided in the bypass pipe 29. When the pressure detection signal of the pressure detector 31 falls below the set value set in the controller 32, the controller 32 immediately opens and closes. Control for opening the valve 30 is performed.
[0032]
When the on-off valve 30 is opened, the exhaust gas 12 from the ash transport pipes 20a to 20f is opened to the decompression tank 24 via the bypass pipe 29 having no decompression orifice 28 and having a small flow resistance, and thus is closed. Is likely to occur, the flow rate of the exhaust gas 12 of the ash transport pipes 20a to 20f is sharply increased, and the problem of blockage is prevented beforehand.
[0033]
In order to prevent the above-mentioned blockage, the temperature detection signals from the thermometers 26 and 27 provided in each of the ash transport pipes 20a to 20f are input to the controller 32 to correct for sudden pressure fluctuation. You can also. However, since there is a time delay from the occurrence of the blockage until the temperature of the exhaust gas 12 in the ash transport pipes 20a to 20f decreases, the control is performed based on the pressure that changes immediately when the blockage is about to occur as described above. It goes without saying that control is performed on the basis of performing
[0034]
If the ash transport pipes 20a to 20f are closed, the blockage is released as follows.
[0035]
That is, in a state where the on-off valve 30 is closed, the shut-off valve 33a of the ash transport pipes 20a to 20f closed for a predetermined time is closed, and at the same time, the blowing on-off valve 33 of the deblocking device 35 is opened to open the pressurized gas source 34. The high-pressure gas is blown into the ash transport pipes 20a to 20f and backwashed to break down the ash in the portion where the clogging has occurred, thereby causing the exhaust gas 12 to flow into the ash transport pipes 20a to 20f and opening the shutoff valve 33a. By opening, the separated ash 18 is discharged to the decompression tank 24. Thereby, the blockage can be released in a state where the pressurized fluidized bed boiler is operated. Note that various gases can be used as the pressurized gas of the pressurized gas source 34 used for releasing the blockage.
[0036]
【The invention's effect】
According to the first aspect of the invention, when the ash transport pipe is about to be clogged by the separated ash, the pressure in the ash transport pipe decreases due to a decrease in the flow rate of the exhaust gas flowing through the ash transport pipe. If the pressure detection signal of the pressure detector is immediately detected by the device and the pressure detection signal of the pressure detector falls below the set value set in the controller, the controller immediately controls the opening and closing of the valve. By being opened, the exhaust gas of the ash transport pipe is opened to the decompression tank via the bypass pipe having a small flow path resistance. Can be prevented beforehand.
[0037]
Further, since the blockage release device is provided in the invention of claim 2, in the event that the ash transport pipe is closed, the blow-off opening and closing valve is opened for a predetermined time while the on-off valve is closed. The high-pressure gas from the pressurized gas source is blown into the ash transport pipe to backwash it, thereby breaking the ash in the clogged portion, thereby causing the exhaust gas to flow in the ash transport pipe and discharging the separated ash to the decompression tank. By doing so, the blockage can be released while the pressurized fluidized bed boiler is operating.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an example of an embodiment of the present invention.
FIG. 2 is a system diagram showing an example of a conventional separated ash transport device of a pressurized fluidized bed boiler.
FIG. 3 is a system diagram showing another example of a conventional separated ash transport device of a pressurized fluidized bed boiler.
[Explanation of symbols]
Reference Signs List 1 pressure vessel 2 fluidized bed boiler 12 exhaust gas 14 cyclone 18 separated ash 20a to 20f ash transport pipe 21 ash cooler 24 decompression tank 28 decompression orifice 29 bypass pipe 30 on-off valve 31 pressure detector 32 controller 33 blow on-off valve 34 pressurization Gas source

Claims (2)

A plurality of cyclones connected to a fluidized-bed boiler installed in the pressure vessel to separate ash in exhaust gas, and separated ash connected to each cyclone and separated by the cyclone through an ash cooler; A separated ash transport device for a pressurized fluidized bed boiler comprising an ash transport pipe leading to an external vacuum tank, and a vacuum orifice arranged at a position adjacent to the vacuum tank of each of the ash transport pipes, wherein each of the vacuum orifices is bypassed. A bypass pipe connecting each of the ash transport pipes to the decompression tank, an on-off valve provided on each of the bypass pipes, a pressure detector disposed upstream of the on-off valve in each of the bypass pipes, A controller that opens a corresponding on-off valve when the pressure detection signal is equal to or less than a set value and closes the corresponding on-off valve when the pressure detection signal is equal to or greater than the set value. Ash transport Location. The apparatus for transporting separated ash of a pressurized fluidized-bed boiler according to claim 1, wherein a pressurized gas source is connected to the bypass pipe via an on-off valve for blowing.

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