JPH0810727Y2 - Pressurized fluidized bed boiler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a pressurized fluidized bed boiler in which a fluidized bed boiler or the like is housed in a pressure vessel to improve combustion efficiency, and particularly, heat recovery efficiency and thermal durability. The present invention relates to a pressurized fluidized bed boiler having a high temperature.

[Prior Art] Conventionally, when a bed material is added to pulverized coal that is made into a slurry, and the fluidized-bed boiler that fluidizes and burns with combustion air has a high pressure in the combustion, the combustion efficiency is improved and Exhaust gas is obtained, which has the advantage of improving power generation efficiency. However, since it is not possible to increase the pressure only in the fluidized bed boiler in terms of strength,
Fluidized bed boiler atmosphere, that is, a pressurized fluidized bed boiler is proposed in which the fluidized bed boiler itself is housed in a pressure vessel and the pressure inside the pressure vessel is increased to reduce the pressure load of the fluidized bed boiler to improve combustion efficiency. ing.

FIG. 6 is an overall view of a conventional pressurized fluidized bed boiler.
As shown in the figure, the pressurized fluidized bed boiler a mainly accommodates a fluidized bed boiler b, a cyclone c, a bed material storage container d, etc. in a closed pressure vessel e, and the inside of the pressure vessel e is about 16
Combustion is performed at a high pressure of ~ 17 atm.

The pressure vessel e is formed in a hollow interior by welding a steel plate or the like into a substantially spherical shape.

Further, the fluidized bed boiler b generally has a fluidized bed forming part h for fluidizing the pulverized coal fuel slurry and the bed material g in the furnace f with combustion air to burn them. The fluidized bed forming portion h is formed on a floor plate i provided at the bottom of a furnace f having an open bottom, and an air nozzle j for introducing combustion air as a fluidizing fluid into the fluidized bed is provided on the floor plate i. It is provided. Therefore, the bed material g is placed on the floor board i.
Is supplied to the bed material g, and the pulverized coal that has been slurried is supplied to the bed material g, and the combustion air for fluidization is supplied from the air nozzle j to fluidize and combust the fuel and the bed material g. In addition, the fluidized bed forming section h of the fluidized bed boiler b
A water pipe n is spirally provided in the water pipe n. The water pipe n is heated to generate steam, and the generated steam drives a steam turbine (not shown) or the like to generate electric power. Further, in the fluidized bed forming portion h of the fluidized bed boiler b, there is provided a bed material storage container d connected to the fluidized bed by a recovery communication pipe k and a circulation communication pipe I. A bed material g is stored to form a fluidized bed of the bed boiler b.

The bed material storage container d has a level control means m for adjusting the pressure in the bed material storage container d to control the level of the fluidized bed, and an air carrying means for carrying the air flow of the bed material g into the fluidized bed boiler b. o is provided, and fluidized bed boiler b
According to the burnup inside the bed, the bed material is collected and recirculated to adjust the level of the fluidized bed to improve the combustion efficiency. That is, when the fuel is reduced, the inside of the fluidized bed boiler b is correspondingly adjusted. In order to reduce the amount of bed material g, the inside of the bed material storage container d is decompressed by the level control means m, and the bed material g is passed through the recovery communication pipe k and recovered in the bed material storage container d to improve the combustion efficiency. When the amount of fuel is increased and the amount of bed material g in the fluidized bed boiler b is increased accordingly, the inside of the bed material storage container d is set to a high pressure by the level control means m, and the bed material g is supplied to the reflux communication pipe 1 To pass into the fluidized bed boiler b.

[Problems to be Solved by the Invention] By the way, as described above, the height of the fluidized bed in the fluidized bed boiler, that is, the amount of the bed material is variably adjusted according to its combustion amount. When the bed material was collected in the bed material storage container by the means, the bed material that became hot due to the combustion in the fluidized bed boiler was temporarily stored in the bed material storage container and was naturally cooled. Was wasted. Further, when the bed material having such a high temperature is collected in the bed material storage container, the bed material storage container and each communication pipe may thermally expand, which may cause damage to the apparatus.

Therefore, the present invention has been devised in order to effectively solve the above-mentioned drawbacks, and it is possible to effectively recover the wasted heat and prevent the device from being damaged. It provides a boiler.

[Means for Solving the Problems] In order to solve the above problems, the first invention is to flow pulverized coal slurried with combustion air in a pressure vessel to which combustion air is supplied together with a bed material. A fluidized bed boiler that combusts while combusting is provided, and is connected to the fluidized bed forming part of the fluidized bed boiler via a recovery communication pipe and a circulation communication pipe, and a part of the bed material is recovered or recirculated from the fluidized bed formation part. In a pressurized fluidized bed boiler provided with a bed material storage container for controlling the level of a fluidized bed, a heat exchanger for recovering heat from the bed material recovered therein is provided in the bed material storage container, Air that has an air hole that surrounds the fluid communication tube of the fluidized bed boiler and that surrounds the fluid communication tube, and that allows a part of the combustion air in the pressure vessel to flow into the boiler along the outer circumference of the fluid communication tube. Chamber tube Is provided. Further, a second invention is configured by interposing a flexible joint for allowing thermal expansion in the recovery communication pipe and the circulation communication pipe.

[Operation] With the above configuration, the latent heat of the bed material that is heated in the fluidized bed boiler and becomes high temperature in the bed material storage container and is recovered is effectively recovered by providing a heat exchanger in the bed material storage container. It became possible to use. Further, by providing an air chamber pipe having an air hole at the connection portion of the fluidized bed boiler with the circulating communication pipe, a part of the combustion air in the pressure vessel is connected to the outer periphery of the communication pipe through the air hole and the air chamber pipe. Since it flows along the inside of the boiler into the boiler, the bed material in the vicinity of the boiler, where the circulating communication pipe is connected, is blown away by the combustion air, so the bed material is easily and reliably supplied from the circulating communication pipe into the boiler. It becomes possible. Further, by providing a flexible joint in the middle of the communication pipe,
It has become possible to allow thermal expansion of the bed material storage container and the communication tube.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a pressurized fluidized bed boiler 1 which is an embodiment of the present invention. As shown in the figure, the pressurized fluidized bed boiler 1 mainly houses a fluidized bed boiler 2, a cyclone 3, a bed material storage container 4 and the like in a pressure container 5, and the inside of the pressure container 5 is supplied with combustion air. It is configured to have a high pressure of about 15 to 17 atmospheres.

The fluidized bed boiler 2 is installed so as to be suspended in the pressure vessel 4 by a plurality of wires 6 and the like as shown in the figure. Further, a fluidized bed forming portion 9 for fluidizing and burning the pulverized coal fuel and the bed material 8 which have been slurried by the combustion air is provided in the cylindrical furnace 7 whose lower portion is tapered. The fluidized bed forming portion 9 is formed on a floor plate 10 provided at the bottom of the furnace 7 having an open bottom,
A plurality of air nozzles 11 for introducing combustion air in the pressure vessel 5 into the fluidized bed as fluidizing fluid are provided on the floor plate 10. Further, a water pipe 12 is spirally provided inside the fluidized bed boiler 2, and is heated by combustion in the boiler 2, and steam generated in the water pipe 12 drives a steam turbine (not shown) to generate electricity. Is going.

A furnace wall 2a of the fluidized bed boiler 2 is formed by vertically arranging a plurality of water pipes 13 made of metal as shown in FIGS. 2 and 3, and a steam extraction header 13a for extracting hot water or steam is provided on the upper part thereof. Further, a water supply header 13b for supplying water is provided below the water supply header 13b. A steam turbine (not shown) is connected to the steam extraction header 13a, and the steam turbine is driven by the steam generated in the water pipe 13. Further, as shown in FIG. 3, the water pipe 13 constituting the furnace wall 2a is provided with fins 14 for keeping the air-tightness of the fluidized bed boiler 2 sufficiently. By welding the fins 14 to each other, the fluidized bed boiler is welded. 2 is formed in an airtight state.

As shown in FIGS. 1 and 4, a bed material storage container 4 for storing a bed material 8 is provided at a side portion of the fluidized bed boiler 2 so as to be suspended by a wire 6 or the like, as in the fluidized bed boiler 2. The fluidized bed forming section 9 of the fluidized bed boiler 2 is connected by a recovery communication pipe 15 and a reflux communication pipe 16. The wall surface 4a of the bed material storage container 4 forms a heat exchanger 17 by arranging a plurality of metal water pipes 13 in a vertical direction or in an oblique direction like the furnace wall 2a of the fluidized bed boiler 2 described above. A water supply pipe 18 for supplying water from the outside is provided at the lower end of the heat exchanger 17.
Is provided, and a water supply pipe 19 for supplying water heated in the bed material storage container 4 to the water supply header 13 is provided at the upper end, and is connected to the water supply header 13.

Further, the bed material storage container 4 has a level control means.
20 and a bed material conveying means 21 are provided.

The bed material conveying means 21 penetrates through the pressure vessel 5 from outside the pressure vessel 5 and a metal circulation pipe 16 that connects the lower portion of the bed material storage container 4 and the side portion of the fluidized bed 9a of the fluidized bed boiler 2 at a right angle. It is composed of an air blowing pipe 16a connected to the bent portion of the reflux communication pipe 16 and a pressure pump 19 for blowing a carrier gas into the air blowing pipe 16a, and the carrier gas is blown into the air blowing pipe 16a by this pressure pump 19. Then, the bed material 8 in the bed material storage container 4 is conveyed by air flow into the fluidized bed boiler 2 through the reflux communication pipe 16.

Further, the level control means 20 is connected to the upper end of the bed material storage container 4 and is provided with a pressure pipe extending through the pressure container 5 to the outside in order to open the inside of the bed material storage container 4 to the atmosphere. 22 and a branch pipe connected to the path of the pressure pipe 22
23 and a control valve for controlling the air pressure in the bed material storage container 4
24, 25 and a pressure pump 26 connected to the branch pipe 23. Then, the pressure pump 25 raises the pressure inside the bed material storage container 4 through the pressure pipe 22, and the control valve 24 opens the inside of the bed material storage container 4 to the atmosphere to reduce the pressure inside the bed material storage container 4. Collection of the bed material 8 from the fluidized bed boiler 2 to the bed material storage container 4, or
Bed material 8 from bed material storage container 4 to fluidized bed boiler 2
Is performed to adjust the amount of the bed material 8 in the fluidized bed boiler 2, that is, the level of the fluidized bed 9a.

On the other hand, as shown in FIG. 4, a flexible joint for allowing thermal expansion of the bed material storage container 4 and the reflux communication pipe 16 is provided in the middle of the reflux communication pipe 16 connecting the bed material storage container 4 and the fluidized bed boiler 2. 27 is provided.

This flexible joint 27 is provided with the circulation communication pipe 16 and the recovery communication pipe 15
Although it is also provided in the above, since the structure is similar, only the circulation communication pipe 16 will be described in detail for convenience of description.

As shown in the drawing, the free-flow communication pipe 16 is divided, and a sliding pipe 28 having a diameter slightly smaller than the inner diameter of the other communication pipe member 16c is provided in the divided communication pipe member 16b on the side of the bed material storage container 4 side. The other end of the sliding pipe 28 is slidably inserted into the end of the other communicating pipe member 16c, and is vertically moved by thermal expansion or contraction. Is allowed. Further, a flexible bellows 29 is provided on the outside of the exposed slide pipe 28 so as to cover it.
The bed material 8 is formed so as not to spill outside when passing through the flexible joint 27. Further, in the connection portion 30 of the fluidized bed boiler 2 with the circulating communication pipe 16, the circulating communication pipe 16 is surrounded, and a part of the combustion air in the pressure vessel 5 is provided along the outer periphery of the circulating communication pipe 16. An air chamber tube 31 having an air hole 35 for inflowing therein is provided. That is, the air chamber pipe 31 and the reflux communication pipe 16 are formed as a double pipe, and the air chamber pipe 31 is strongly reinforced by the reinforcing plate 32.

On the other hand, as shown in FIG. 5, the pressure vessel 5 is formed into an inner hollow by welding a steel plate or the like into a substantially cylindrical shape. And
Reinforcing ribs 34 are provided around the body 33 in the circumferential direction and the vertical direction to enhance the strength of the pressure vessel 5.

 Next, the operation of the present invention will be described.

Water is supplied from the water supply pipe 18 to the heat exchanger 17 in the bed material storage container 4 and the water pipe 13 of the fluidized bed boiler 2, and the operation of the pressurized fluidized bed boiler 1 is started. Then, if the electricity demand and the like increase and the combustion load of the fluidized bed boiler 2 rises, the amount of fuel injected into the fluidized bed boiler 2 is increased to achieve high combustion. At that time, the amount of injected fuel is increased. Accordingly, the level of the fluidized bed 9a, that is, the amount of the bed material 8 needs to be similarly increased. For that purpose, first, the fluidized bed 9a in the fluidized bed boiler 2 is fluidized, the control valve 22 of the branch pipe 23 is opened, and then air is blown in by the pressure pump 26 to raise the pressure in the bed material storage container 4, The bed material 8 in the bed material storage container 4 starts to move to the fluidized bed forming portion 9 in the fluidized bed boiler 2 through the reflux communication pipe 16, and this operation is performed until a desired level is reached. At this time, the air blowing pipe which is the air conveying means 21.
By blowing air into the 16a from the pressure pump, the movement of the bed material 8 becomes easier. Further, since a part of the combustion air in the pressure vessel 5 flows into the boiler 1 along the outer circumference of the reflux communication pipe 16 via the air hole 35 and the air chamber pipe 31, the circulation communication pipe 16 in the boiler 1 is connected. Since the bed material 8 near the portion is blown off by the combustion air, the bed material 8 can be easily and surely supplied into the boiler 1, and the bed material can be reliably recirculated.

Next, when the combustion load of the fluidized bed boiler 2 becomes low, the fuel injected into the fluidized bed boiler 2 is reduced, and similarly, the amount of the bed material 8 is also reduced to improve the combustion efficiency. For that purpose, first, after closing the control valve 25 of the branch pipe 23, gradually opening the control valve 21 of the pressure pipe 22 to open the inside of the bed material storage container 4 to the atmosphere, the inside of the bed material storage container 4 is decompressed, and the pressure is reduced. The bed material 8 heated by combustion in the fluidized bed boiler 2 for the sake of balance begins to flow into the bed material storage container 4 through the recovery communication pipe 15, and the level of the fluidized bed 9a in the fluidized bed boiler 2 is increased. Gradually lowers. When the level of the fluidized bed 9a reaches a desired height, the control valve 24 is closed to stop the movement of the bed material 8.

As described above, the movement of the bed material 8 in the bed material storage container 4 is circulated by increasing the pressure in the bed material storage container 4 higher than the pressure in the fluidized bed boiler 2, and the pressure in the fluidized bed boiler 2 is also increased. The level of the fluidized bed 9a in the fluidized bed boiler 2 is adjusted by recovering by lowering the pressure.

Then, the fluidized-bed boiler 2 is heated with combustion,
The bed material 8 collected in the bed material storage container 4 is cooled by the heat exchanger 17 provided in the bed material storage container 4. On the other hand, the water heated by removing the heat of the bed material 8 is sent from the water supply pipe 19 to the water supply header 13b of the fluidized bed boiler 2 to become steam, which is taken out from the steam extraction header 13a,
It is used as a drive source for steam turbines.

Further, when the bed material 8 heated as described above is collected in the bed material storage container 4 via the collection communication pipe 15,
Along with this, the recovery communication pipe 15, the bed material storage container 4 and the reflux communication pipe 16 cause thermal expansion, however, these thermal expansions are allowed by the flexible joint 27, and the stress is exerted on each connection. It does not interfere with the strength of the parts.

The flexible joint 27 is the recovery communication pipe 15 in this embodiment.
It was used in the vertical part of the circulating communication pipe 16 and the air blowing pipe 16
Needless to say, it may be provided at other locations such as a and the pressure tube 22 that are affected by thermal expansion and contraction.

Further, as shown in FIG. 4, the heat exchanger 17 provided on the wall surface of the bed material storage container 4 has a double shell structure for the bed material storage container 4, and a heat medium such as water is made to flow in the gap. Alternatively, if the water pipe is spirally provided in the bed material 8 in the bed material storage container 4, the heat exchange efficiency is further improved.

[Effect of the Invention] The present invention has the following excellent effects.

(1) Energy efficiency is improved by effectively utilizing the latent heat of the recovered heating bed material, and the bed material can be reliably recirculated.

(2) Since the flexible joint that allows the thermal expansion is provided, the device is prevented from being broken and the durability is improved.

[Brief description of drawings]

FIG. 1 is an overall view showing an embodiment of the present invention, FIG. 2 is a vertical and horizontal broken perspective view showing a furnace wall structure of a fluidized bed boiler, FIG. 3 is a partially enlarged sectional view of the same, and FIG. FIG. 5 is an enlarged sectional view showing a flexible joint portion of a communication pipe, FIG. 5 is a broken perspective view showing a pressure vessel, and FIG. 6 is an overall view of a conventional pressure type fluidized bed boiler. In the figure, 1 is a pressurized fluidized bed boiler, 2 is a fluidized bed boiler, 4 is a bed material storage container, 5 is a pressure vessel, 8 is a bed material, 9 is a fluidized bed forming section, 9a is a fluidized bed, and 15 and 16 are communicating. A tube, 17 is a heat exchanger, and 27 is a flexible joint.

Claims (2)

[Scope of utility model registration request] 1. A pressure vessel to which combustion air is supplied is provided with a fluidized bed boiler for combusting pulverized coal slurried by the combustion air in the vessel while fluidizing it together with a bed material. A bed material storage container is provided which is connected to the fluidized bed forming portion via a recovery communication pipe and a reflux communication pipe, and controls or controls the level of the fluidized bed by collecting or circulating a part of the bed material from the fluidized bed formation portion. In the pressure type fluidized bed boiler, the bed material storage container is provided with a heat exchanger for recovering heat from the bed material recovered in the bed material storage container, and the communication pipe is connected to a connection portion of the fluidized bed boiler with a reflux communication pipe. And a pressure type fluidized bed boiler, which is provided with an air chamber tube having an air hole for surrounding part of the combustion air in the pressure vessel and flowing into the boiler along the outer circumference of the communication tube. 2. The pressure type fluidized bed boiler according to claim 1, wherein a flexible joint for allowing thermal expansion is provided in the recovery communication pipe and the circulation communication pipe.