JP2000266306A - Pressurized fluidized-bed boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove a mineral matter of rough particles stored in a flow medium of a pressurized fluidized-bed combustion furnace having low cost and simple facility, by providing a rough particle separator on the way of an air flow conveying tube or in a medium container, removing rough particles in the medium, and then storing the particles in the container. SOLUTION: A rough particle separator 26 is provided at an air flow transport tube 13 at a front flow of a medium container 14, and a cooler 50 is provided at the tube 13 at the front flow of the separator 26. A flow medium supplied via the tube 13 and a valve 28 is sorted out on a screen 27, and the medium passed through the screen 27 is stored as flow medium 20 in the container 14 via the valve 29. The medium of rough particles containing a shear which did not pass through the screen 27 is slid on the screen 27 and stored at a lower end of the screen 27, and introduced into a rough particle storage container 32 through a discharge tube 30 and a valve 31 connected to the lower end. The level of the particles in the container 32 is monitored with an inspection window 33 the valve 31 is closed, a valve 35 is opened, and the particles are discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized fluidized-bed boiler, and more particularly, to load control by changing the height of a fluidized bed suitable for performing combined power generation by driving a gas turbine, a steam turbine or the like. The present invention relates to a pressurized fluidized-bed boiler.

[0002]

2. Description of the Related Art In a pressurized fluidized-bed boiler, a fluidized medium in a fluidized-bed combustion furnace is taken in and out to increase or decrease the height of a fluidized bed to control a load change. That is, when lowering the load, the fluidized medium in the fluidized bed combustion furnace is extracted from the furnace and temporarily stored in a separate medium container. Conversely, when the load is increased, the fluidized medium is removed from the medium container. By supplying the fluid into the fluidized bed combustion furnace, the height of the heat transfer tube in the furnace is immersed in the fluid medium to change the heat transfer area, and the amount of generated steam is changed to control the load change. .

FIG. 9 is an explanatory view of a conventional pressurized fluidized bed boiler. 9, the pressurized fluidized-bed boiler includes a pressurizing device 1 and a medium container 14, and the pressurizing device 1 is included in the fluidized-bed combustion furnace 2 and the exhaust gas discharged from the fluidized-bed combustion furnace 2. A cyclone 8 for removing dust and the like to be removed, and an exhaust pipe 9 for discharging the exhaust gas from which the dust and the like have been removed to the outside of the system. The fluidized bed combustion furnace 2 includes a fluidized medium 4 for forming a fluidized bed 5 and a coal feed pipe 6 for supplying coal to the fluidized bed 5.
And an air distribution plate 3 for supplying combustion air for burning the coal supplied to the fluidized bed 5 to the fluidized bed 5, a heat transfer tube 7 embedded in the fluidized bed 5, and a fluid for forming the fluidized bed 5. A fluidized bed extraction pipe 11 for extracting the medium 4;
And a supply pipe 21 for supplying the fluidized medium 20 stored in the medium container 14 to the fluidized bed combustion furnace 2. The fluidized bed extraction pipe 11 is provided with an opening at the lower part of the side wall of the fluidized bed combustion furnace 2, and an L valve 12 is provided at the lower end thereof.
An air flow transport pipe 13 is connected to the end of the valve 12, and the medium container 1 installed at the tip of the air flow transport pipe 13
An exhaust pipe 16 and a pressure reducing valve 17 are connected to the empty tower section 15 of 4 and communicate with the outside of the system.

In such a configuration, a fluidized bed combustion furnace 2 housed in a pressure vessel 1 forms a fluidized bed 5 with combustion air supplied through an air distribution plate 3, and fuel coal is supplied to a coal feed pipe. The fluid is supplied into the fluidized bed 5 from the fuel tank 6 and burned, and the heat transfer tubes 7 arranged in the fluidized bed 5 absorb the heat of combustion and generate steam in the tube. The flue gas generated by the combustion of the coal in the fluidized bed 5 is dedusted by the cyclone 8,
It is discharged out of the system via the exhaust pipe 9 and the pressure reducing valve 10.

[0005] Fluctuation of fluidized bed height due to load change is as follows.
This is performed by the following means. That is, when lowering the bed height of the fluidized bed 5, the fluidized medium 4 is filled with the fluidized bed extraction pipe 11,
The liquid is guided to the medium container 14 through the L valve 12 and the air flow transport pipe 13 and is temporarily stored as the flowing medium 20. The transport of the fluid medium 4 by the airflow transport pipe 13 is performed by a transport gas supplied from the pressure vessel 1 via a valve 18, and the gas passes through an exhaust pipe 16 downstream of the medium vessel 14 and a pressure reducing valve 17. It is led out of the system. The flow rate of the fluid medium 4 is adjusted by adjusting the amount of carrier gas supplied from the pressure vessel 1 to the L valve 12 via the valve 19.

[0006] By lowering the fluidized bed height in this way, the immersion of the in-furnace heat transfer tube 7 in the fluidized medium 4 becomes shallower,
Since the heat transfer area is reduced, the load is reduced. When the load is increased, the fluid medium 20 stored in the medium container 14 is supplied to the fluidized bed 5 through the supply pipe 21 and the L valve 22 by the supply pipe gas supplied from the pressure vessel 1 via the valve 23. To increase the height of the fluidized bed.

In the above-described conventional method of circulating a fluid medium,
At the time of the load change, the fluidized medium 4 having a high temperature of about 850 ° C. is drawn out of the fluidized bed combustion furnace 2 into the medium container 14. At this time, since the gas in the pressure vessel 1 used for transporting the medium is air, it contains about 21% of oxygen.
When the load is not changed, the flowing medium 20 is stored in the medium container 14 in a fixed layer state for a long time. Due to these factors, the unburned coal particles contained in the fluidized medium 20 are adiabatically burned in the medium container 14 having a high temperature and a high oxygen concentration, and the temperature is excessively increased, and the ash and the fluidized medium are removed. When melted, agglomerates 24 are generated. Agglomeration 2 like this
4 is a flow medium 2 in the medium container 14 for increasing the load.
When transferring 0 to the fluidized bed, there is a risk that the supply pipe 21 may be blocked, so that not only a smooth load change cannot be performed, but in the worst case, the operation of the fluidized bed combustion furnace 2 is stopped.

A method of supplying an inert gas such as nitrogen into the medium container may be employed to avoid the solidification of the medium particles which cause such blockage. However, the inert gas is stored and supplied. At present, large-scale equipment is required, and the cost is considerably high.

On the other hand, in the fluidized bed 5, for example, coal pulverized to a size of 6 to 10 mm or less, limestone pulverized to a size of 3 mm or less as a desulfurizing agent, and water are mixed to form a CW paste.
P (Coal Water Paste) is supplied through a coal feed pipe 6. The reason why CWP is used is that if dry coal is used, the temperature distribution in the bed becomes large, and the use of coarsely pulverized coal is to make the water content of CWP as small as possible. Since the coal is used in the coarse pulverization, coarse particles of a mineral having a maximum diameter of 6 to 10 mm contained in the coal are also introduced into the bed. Fine minerals, CaSO ₄ formed by the reaction of limestone and SO ₂ , and CaO decalcified from limestone are abraded and most of them are scattered outside the combustion furnace, but coarse minerals are hard to wear and flow. It will stay in layer 5.

[0010] Such coarse-grained mineral substances are called debris, and debris accumulates in the fluidized bed 5 when the operation of the pressurized fluidized-bed boiler is continued for a long time. Generally, the shear has a large hardness, and when the shear increases, it flows like the fluid medium 4 and accelerates the wear of the heat transfer tube 7. In addition, if the amount of shear increases, poor flow of the fluid medium 4 occurs, causing problems such as agglomeration 24 and a decrease in desulfurization rate. Therefore, usually, the fluidized medium 4 is periodically sampled from the fluidized bed extraction pipe 11 at the bottom of the furnace, and when the fluidized medium 4 of 6 mesh (3.35 mm) or more becomes, for example, 5% by weight or more, the fluidized medium 4 is subjected to fluidized bed combustion. It is pulled out from the bottom of the furnace 2 to remove the scrap. However, in this method, not only the waste but also the limestone in the furnace contributing to desulfurization is discarded at the same time, which is uneconomical.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional method, and to provide a low-cost and simple facility with the use of minerals of coarse particles accumulated in a fluidized medium of a pressurized fluidized bed combustion furnace. An object of the present invention is to provide a pressurized fluidized-bed boiler capable of easily removing quality and smoothly extracting and supplying a fluidized medium for load control.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above problems and found that (a) a structure in which particles of a flowing medium are divided according to size between a bed height control airflow transport pipe and a medium container. (B) Install a screen with an opening that allows the fluid medium to pass through, for example, 3 mm or more. (C) Incline the screen, A discharge pipe for removing coarse particles is connected to a portion where the lower end is in contact with the inner wall of the medium container,
(d) Provide a valve in the system of the air flow transport pipe and the supply pipe so that clogging of the screen can be cleaned. (e) Provide a cooling device for the flowing medium in consideration of protection of the valve and safety when cleaning the screen. (F) installing a fluidized bed at the lower end of the airflow transport pipe, the flow velocity of the transport gas in the airflow transport pipe,
(G) As a gas for transporting the medium between the fluidized bed combustion furnace and the medium container, a gas having a lower oxygen concentration than air, such as a fluidized bed combustion furnace, is provided. Using exhaust gas, (h) the inventors have found that it is possible to solve the above problem by mixing a gas having a lower oxygen concentration than the exhaust gas into the exhaust gas of a fluidized bed combustion furnace and using it as a medium transport gas, and reached the present invention. It is.

That is, the invention claimed in the present application is as follows. (1) a pressurized fluidized bed combustion furnace having a fluidized medium and a heat transfer tube provided in a fluidized bed of the fluidized medium; an exhaust pipe for discharging exhaust gas discharged from the fluidized bed combustion furnace to outside the system; A fluidized medium extraction pipe for extracting a fluidized medium from a fluidized bed combustion furnace, a medium container for storing the fluidized medium extracted from the fluidized bed combustion furnace, and a pneumatic transport for transporting the extracted fluidized medium to the medium container In a pressurized fluidized-bed boiler provided with a pipe and a supply pipe for supplying a fluidized medium stored in the medium container to the fluidized-bed combustion furnace, a coarse particle separation device is provided in the middle of the airflow transport pipe or in the medium container. A pressurized fluidized-bed boiler, wherein coarse particles in a fluidized medium are removed and then stored in the medium container. (2) The pressurized fluidized-bed boiler according to (1), wherein the coarse particle separation device includes an aperture screen of 3 mm or more.

(3) The coarse-grain separation device is connected to the atmosphere via a valve through the air flow transport pipe or the supply pipe upstream and downstream of the coarse-grain separation device, so that the coarse-grain separation device can be operated at atmospheric pressure. The pressurized fluidized-bed boiler according to (1) or (2), wherein (4) The pressurized fluidized-bed boiler according to any one of (1) to (3), wherein a cooling device is provided in an airflow transport pipe upstream of the coarse particle separation device. (5) A fluidized bed device is provided at the lower end of the gas flow transport pipe, and the fluidized bed apparatus has a flow rate of the transport fluid in the gas flow transport pipe of coarse particles separated from the fluid medium extracted from the fluidized bed combustion furnace. The pressurized fluidized-bed boiler according to any one of (1) to (4), further comprising means for supplying a fluid so as to have a terminal speed. (6) A pipe for connecting the exhaust pipe and the airflow transport pipe is provided, and an inert gas that does not reach an oxygen content that causes combustion of unburned components in the fluid medium in the medium container is transported to the fluid medium. The pressurized fluidized-bed boiler according to any one of (1) to (5), further comprising a system for supplying a supply gas to the pipe. (7) A gas supply means is provided in the pipe, and a supply system of a mixed gas of an exhaust gas and a gas having a lower oxygen concentration than the exhaust gas is provided as a gas for transporting the fluid medium (1) to (1). The pressurized fluidized-bed boiler according to any one of (6).

[0015]

When the load of the fluidized bed combustion furnace 2 is reduced in FIG. 9, the fluidized medium 4 in the fluidized bed 5 is withdrawn at a high temperature.
It is transported by the air of the pressurized container 1 and supplied to the medium container 14, and the flowing medium 20 in the medium container 14 forms a fixed layer when the load is not changed. The fluid medium 20 contains unburned coal particles, and has a high oxygen concentration in the atmosphere. Therefore, the fluid medium 20 burns adiabatically, causing a local temperature rise, melting the ash and the surrounding medium to form the agglomerates 24. Leads to outbreak. That is, in order for agglomerates to be generated, two conditions of “high temperature” and “high concentration of oxygen” for burning unburned coal particles are necessary. Generation can be suppressed.

In the present invention, since coarse particles including debris are removed from the fluidized medium extracted from the fluidized bed and then supplied to the fluidized bed via the medium container, the fluidized medium supplied to the fluidized bed is supplied to the fluidized medium. Since it does not contain debris or coarse particles, it is possible to prevent abrasion of the heat transfer tube, generation of agglomeration, reduction in desulfurization rate, and the like. In addition, since a gas having an oxygen concentration lower than that of air, such as flue gas, is used for transporting the fluidized medium, combustion of unburned coal particles in the medium container is suppressed, agglomeration is prevented, and the fluidized medium is transported to the fluidized bed. Clogging in the piping for supplying water can be prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a peripheral portion of a medium container 14 attached to a pressurized fluidized-bed boiler showing one embodiment of the present invention. 1 is different from FIG. 9 of the conventional apparatus in that two coarse particle separators 26 are provided in the air flow transport pipe 13 upstream of the medium container 14.
And a cooling device 50 is installed in the airflow transport pipe 13 upstream of the coarse particle separator 26. In FIG. 1, coarse separator 2
Reference numeral 6 denotes a hopper-type container in which the inside of the hopper is partitioned by an inclined screen 27 in a sectional direction. The screen 27 is preferably, for example, a punching plate having a mesh size of 3 mm or more so that coarse particles do not easily pass through. The fluid medium 4 supplied via the airflow transport pipe 13 and the valve 28 is
The liquid which has been separated on the screen 27 and passed through the screen is transferred to the medium container 14 via the valve 29 and the fluidized medium 20.
Is stored as From the air flow transport pipe 13, the coarse particle separator 2
The fluid medium entering 6 is water-cooled by a jacket-type cooling device 50 in order to prevent damage to the valve 28 due to a rise in temperature.

The coarse particle separator 26 is provided with a viewing window 34 for monitoring the clogging of the screen. When the screen is clogged, the ball valves 28 and 29 are closed, and the ball of the coarse particle storage container 32 is closed. The valve 35 is opened to remove coarse particles, and the backwash air valve 46 is opened to clean the screen 27. If the clogging of the screen still cannot be cleared, it is possible to disassemble and clean the screen by closing the ball valves 28 and 29 and opening the ball valve 35 to return the inside of the coarse particle separator to normal pressure. By installing a plurality of coarse particle separators 26, the operation can be continued using another coarse particle separator even during backwashing and disassembly cleaning. On the other hand, the coarse-grained fluid medium 4 containing the debris that has not passed through the screen 27 slides on the screen and accumulates at the lower end of the screen 27, and the discharge pipe 30 connected to the lower end.
And into the coarse particle storage container 32 via the valve 31. The level of the coarse particles in the coarse particle storage container is monitored by a viewing window 33. When the level reaches a predetermined level, the valve 31 is closed and the valve 35 is opened to discharge the coarse particles.

FIG. 2 is an explanatory view of a peripheral portion of a medium container of a pressurized fluidized-bed boiler showing still another embodiment of the present invention. 2 is different from FIG. 1 in that an upper medium container 41 and a lower medium container 44 are provided vertically instead of the medium container 14, and a coarse particle separator 26 is provided therebetween. In FIG. 2, the pressure reducing valve 17 of the upper medium container 41 is opened to reduce the pressure of the upper medium container 41, and the fluid medium 20 is transferred to the upper medium container 41 via the airflow transport pipe 13 and the ball valve 42.
To store. A medium cooling coil 43 is provided in the upper medium container 41 to lower the temperature of the flowing medium 20.

The upper medium container 41 contains a certain amount of the fluid medium 2.
When 0 is accumulated, the transport of the flowing medium 4 to the upper medium container 41 is stopped, and the pressure reducing valve 17 and the ball valve 42 are closed. The coarse particles of the flowing medium 20 stored in the upper medium container 41 are separated by the coarse particle separator 26 in the same manner as in FIG. When the ball valve 45 on the medium outlet side of the lower medium container 44 is closed, the pressure reducing valves 17 of the upper medium container 41 and the lower medium container 44 are opened, and the upper and lower ball valves 28 and 29 of the coarse particle separator 26 are opened. ,
The system can be kept at atmospheric pressure, coarse particles can be separated at normal pressure and room temperature, and the inside of the coarse particle separator 26 is more effectively backwashed than when pressurized, and the screen is clogged. It is easy to respond to

FIG. 3 is an explanatory view showing a peripheral portion of a medium container of a pressurized fluidized-bed boiler showing still another embodiment of the present invention. 3 is different from FIG. 9 in that, instead of the medium container 14, a cooling device 50 for cooling the medium container 44 in which the screen 27 is built and the airflow transport pipe 13 is provided. In FIG. 3, the medium container 44 is depressurized by opening the ball valve 42 and the pressure reducing valve 17 of the medium container 44, and the flowing medium 20 is stored in the medium container 44 through the airflow transport pipe 13 and the ball valve 42. The air flow transport pipe 13 is provided with the cooling device 5.
Water cooling by 0 protects the ball valve 42 from burning. The coarse particles are separated by dropping the flowing medium 4 on the screen 27 installed in the medium container 44.
The separated coarse particles pass through the discharge pipe 30 and are stored in the coarse storage container 32.
To be stored. When the screen 27 is clogged,
Open the backwash air valve 46 for cleaning. In the case of this embodiment,
By closing the ball valves 42 and 45 and reducing the pressure to the atmosphere by the pressure reducing valve 17 of the medium container 44, the manhole 46 can be opened and the screen 27 can be cleaned.

FIG. 4 is an explanatory view of a peripheral portion of a medium container of a pressurized fluidized-bed boiler showing still another embodiment of the present invention. 4 is different from FIG. 3 in that the coarse particle pool 5 is provided at the lower end of a screen 27 that is provided to be inclined in a medium container 44.
4 is provided so that the coarse particles accumulated in the coarse particle reservoir 54 are discharged to the coarse particle storage container 53 through the discharge pipe 52. In the apparatus of FIG. 4, when the inner diameter of the medium container 44 is increased, even if the discharge pipe 30 is provided at the lower end of the screen 27, coarse particles are not discharged from the discharge pipe 30 but tend to accumulate around the discharge pipe entrance. By providing the coarse particle pool 54, such a problem can be eliminated.
It is preferable that the coarse-grain reservoir 54 is attached with the same material as the screen 27. The state of accumulation of coarse particles is monitored through the viewing window 47. When the coarse particles accumulate, the pressure reducing valve 17, the ball valve 42 are closed and the ball valve 51 is opened, and the medium container 44 is in a pressurized state. Therefore, the coarse particle pool 54
The coarse particles accumulated in the medium can be discharged to the coarse particle storage container 53 through the discharge pipe 52 together with the air in the medium container.

FIG. 5 is an explanatory view of a peripheral portion of a medium container of a pressurized fluidized-bed boiler showing still another embodiment of the present invention. 5 differs from FIG. 2 in that the coarse particle separator 26 installed between the upper medium container 41 and the lower medium container 44 is separated from the upper medium container 41 and the lower medium container 44 (that is, the pressure container (Separated from the system). In FIG. 6, the pressure reducing valve 17 of the upper medium container 41 is opened to depressurize the upper medium container 41, and the fluid medium 20 is supplied to the upper medium container 41 via the airflow transport pipe 13 and the ball valve 42.
To store. A medium cooling coil 43 is installed in the upper medium container 41 to lower the temperature of the flowing medium 20. Next, the ball valve 45 of the supply pipe 13 of the lower medium container 44 is closed, and the pressure reducing valve 17 of the lower medium container 44 is opened to reduce the pressure in the container to the atmospheric pressure. Next, the ball valve 28 is opened and the flowing medium 20 in the upper medium container 41 is separated from the coarse particle separator 26.
On the screen 27. The coarse-grained fluid medium rolls on the screen 27 and enters the coarse-grain storage container 32 through the discharge pipe 30. In the present embodiment, since the coarse particle separator 26 is cut off from the pressure vessel or the like, it becomes easy to attach the vibrator 31 to increase the efficiency of the separation operation.

FIG. 6 is an explanatory view of the vicinity of the lower end of the air flow transport pipe of the pressurized fluidized bed boiler showing another embodiment of the present invention.
6 is different from FIG. 9 in that a fluidized bed apparatus 61 is provided at the lower end of the airflow transport pipe 13 and the fluidized bed apparatus 61 is provided with coarse particles in which the flow rate of the transport gas in the airflow transport pipe is separated from the fluid medium. Means for supplying the fluid so as to achieve the terminal speed of In FIG. 6, a flow meter orifice 62, a flow control valve 63,
4 and a fluidized bed apparatus 61 having an air nozzle 65 are provided. The fluid medium 4 supplied into the fluidized bed apparatus 61 from the L valve 12 is supplied to the flow meter orifice 62 and the flow regulating valve 6.
3. It is mixed with fluidizing air supplied through the diffuser pipe 64 and the air nozzle 65 and fluidized.

At this time, the amount of fluidizing air is set so that the flow velocity in the pneumatic transport tube becomes the terminal velocity of the particle size to be separated. The terminal speed is measured by a thermocouple 66 as a temperature detector.
The temperature measured by the above, the pressure measured by the pressure detector 67, the size of the particle to be removed (for example, 4 mm if it is 4 mm or more),
It can be obtained from the true specific gravity using a known formula such as Wen-Yu. FIG. 7 shows the relationship between the particle diameter of the fluidized medium and the terminal speed obtained by this calculation formula. If it is desired to separate at 4 mm, by controlling the flow velocity in the air flow transport tube to 10.2 m / s, particles of 4 mm or less are scattered in the air flow transport tube together with the transport gas and a medium container (not shown) provided upstream thereof The coarse particles exceeding 4 mm are segregated in the fluidized bed apparatus 61. The coarse particles can be discharged out of the system via a discharge pipe 68 and a ball valve 69. In this embodiment, since there is no mechanical component for separating coarse particles of the fluid medium having a high temperature, an advantage that heat resistance does not need to be considered is added.

FIG. 8 is an explanatory view of a pressurized fluidized-bed boiler showing another embodiment of the present invention. FIG. 8 differs from FIG. 9 of the conventional apparatus in that the exhaust gas of the fluidized bed combustion furnace is used as a transport gas for the fluidized medium when the load changes, for the purpose of lowering the oxygen concentration in the medium container 14. Is a point.
That is, the exhaust pipe 9 is branched, and the exhaust gas from the fluidized-bed combustion furnace 2 is supplied to the pipe 101, and the three-way valve 103 provided in the middle thereof.
The pneumatic transport pipe 1 is connected via a dust remover 102, a valve 18, and an L valve 12 which are switchably arranged in two rows.
3 is connected. In this case, the pipe 101 is supplied so that an inert gas such as nitrogen can be supplied through the valve 104.
Are provided as branch pipes. The dust removal device 102 is provided to remove fine fly ash that cannot be collected by the cyclone 8 in the exhaust gas, and is provided to remove the fine fly ash. Can be used.

According to such an apparatus, since the exhaust gas having a considerably low oxygen concentration of, for example, 3.5% is used as the transport gas for the fluid medium, the fluid medium is extracted and stored in the medium container when the load changes. At this time, combustion of the unburned coal particles in the medium container can be suppressed. Further, by switching the flow path of the exhaust gas by the three-way valve 103, it is possible to use one dust removing device 102 and clean or replace the other dust removing device 102. Further, when the oxygen concentration in the exhaust gas is high or the unburned coal particles are large, the oxygen concentration of the transport gas can be reduced by supplying an inert gas through the valve 104. The embodiment shown in FIG. 8 can be applied to a general pressurized fluidized bed boiler in addition to being used in combination with the apparatus of the embodiment shown in FIGS.

[0028]

According to the first to fifth aspects of the present invention, since coarse particles including agglomerates are separated from the fluidized medium and supplied to the fluidized bed combustion furnace, wear of the heat transfer tube can be prevented. It is possible to prevent the occurrence of poor flow and to prevent the medium supply pipe to the fluidized bed combustion furnace from being clogged, thereby enabling smooth load control of the fluidized bed. According to the invention according to claims 6 and 7 of the present application, the combustion of unburned coal particles is suppressed by lowering the oxygen concentration in the medium container, and the occurrence of agglomeration in the medium container is prevented. Blockage in the medium supply pipe to the medium can be prevented. This enables smooth load control of the fluidized bed. In addition, expensive nitrogen gas which has been conventionally used to prevent agglomeration is not required, or the effect of preventing agglomeration can be obtained with a small amount of use, so that the cost can be reduced.

[Brief description of the drawings]

FIG.

FIG.

FIG.

FIG.

FIG. 5 is an explanatory view of a peripheral portion of a medium container of a pressurized fluidized-bed boiler showing an embodiment of the present invention.

FIG. 6 is an explanatory view showing the vicinity of a lower end portion of an airflow transport pipe of a pressurized fluidized-bed boiler showing another embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a particle diameter of a fluid medium and a terminal speed.

FIG. 8 is an explanatory view of a pressurized fluidized-bed boiler showing one embodiment of the present invention.

FIG. 9 is an explanatory view of a pressurized fluidized-bed boiler according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pressure vessel, 2 ... Fluidized bed combustion furnace, 3 ... Air dispersion plate, 4
... fluidized medium, 5 ... fluidized bed, 6 ... coal feed pipe, 7 ... heat transfer pipe, 8
... cyclone, 9 ... exhaust pipe, 11 ... fluid medium layer withdrawal pipe, 12 ... L valve, 13 ... air flow transport pipe, 14 ... medium container, 16 ... exhaust pipe, 20 ... fluid medium, 21 ... supply pipe, 2
4 ... Agglomerated, 26 ... Coarse particle separator, 27 ... Screen,
Reference numeral 30 denotes a discharge pipe, 32 denotes a coarse-grained storage container, 33 and 34 denotes a viewing window, 36 denotes a vibrator, 41 denotes an upper medium container, 4
DESCRIPTION OF SYMBOLS 3 ... Medium cooling coil, 44 ... Lower medium container, 46 ... Backwash air valve, 47 ... Funnel, 50 ... Cooling device, 53 ... Coarse particle storage container, 54 ... Coarse particle storage, 61 ... Fluidized bed apparatus, 101
... Piping, 102 ... Dust removal device, 103 ... Three-way valve, 104 ...
valve.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinori Otani 3-36 Takara-cho, Kure-shi, Hiroshima Pref. Inside the Kure Laboratory (72) Inventor Wakako Shimohira 3-36 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi, Ltd. Inside the Kure Research Laboratory (72) The inventor Manabu Yamamoto 3-36 Takara-cho, Kure City, Hiroshima Prefecture Inside the Kure Research Laboratory, Babcock Hitachi Co., Ltd. (72) The inventor Shinichiro Nomura 3-36 Takaracho, Kure City, Hiroshima Prefecture, Babcock Hitachi Kure Research Laboratory Terms (reference) 3K064 AA08 AA15 AA18 AB01 BA07 BA11 BA14 BA19 BA24 BB05 BB07 BB09

Claims (7)

[Claims] 1. A pressurized fluidized bed combustion furnace having a fluidized medium and a heat transfer tube provided in the fluidized bed of the fluidized medium, and an exhaust pipe for discharging exhaust gas discharged from the fluidized bed combustion furnace to outside the system. A fluid medium extraction pipe for extracting a fluid medium from the fluidized bed combustion furnace, a medium container for storing the fluid medium extracted from the fluidized bed combustion furnace, and transporting the extracted fluid medium to the medium container In a pressurized fluidized-bed boiler provided with an airflow transport pipe and a supply pipe for supplying a fluidized medium stored in the medium container to the fluidized-bed combustion furnace, coarse particles are separated in the middle of the airflow transport pipe or in the medium container. A pressurized fluidized bed boiler provided with an apparatus, wherein coarse particles in a fluidized medium are removed and then stored in the medium container. 2. The pressurized fluidized-bed boiler according to claim 1, wherein the coarse-grain separation device includes an aperture screen having a size of 3 mm or more. 3. The method according to claim 1, wherein the air flow transport pipe or the supply pipe upstream and downstream of the coarse particle separation device is connected to the atmosphere via a valve so that the coarse particle separation device can be operated under atmospheric pressure. The pressurized fluidized-bed boiler according to claim 1 or 2, wherein: 4. The pressurized fluidized-bed boiler according to claim 1, wherein a cooling device is provided in an air flow transport pipe upstream of the coarse particle separation device. 5. A fluidized bed apparatus is provided at a lower end portion of the gas flow transport pipe, and the fluidized bed apparatus has a coarse fluid flow rate of a transport fluid in the gas flow transport pipe separated from a fluid medium extracted from the fluidized bed combustion furnace. The pressurized fluidized-bed boiler according to any one of claims 1 to 4, further comprising means for supplying a fluid so as to have a terminal velocity of the particles. 6. A pipe connecting the exhaust pipe and the pneumatic transport pipe, wherein an inert gas of an extent not reaching an oxygen content that causes combustion of unburned components in the fluid medium in the medium container is supplied to the fluid medium. The pressurized fluidized-bed boiler according to any one of claims 1 to 5, further comprising a system that supplies the transport gas to the pipe. 7. A gas supply means is provided in the pipe, and a supply system of a mixed gas of an exhaust gas and a gas having an oxygen concentration lower than the exhaust gas is provided as a gas for transporting a fluid medium. The pressurized fluidized-bed boiler according to any one of claims 1 to 6.