JP2909296B2 - Fluidized bed height control device for combustion furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed height control apparatus for a combustion furnace which can control the height of a pressurized fluidized bed without lowering the thermal efficiency of a plant.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional apparatus for controlling the height of a pressurized fluidized bed of a combustion furnace. In a combustion furnace 2 having a heat transfer tube 1 disposed in a pressurized fluidized bed formed by a fluidized material 7, an air distribution plate provided in a lower portion of the combustion furnace 2 by coal flow of air and limestone 12 by air 6 5 above. The coal 4 burns in the fluidized material 7, but the heat is released when the water supplied to the heat transfer tube 1 evaporates, and the temperature becomes about 850 ° C. The steam in the heat transfer tube 1 is sent to drive a steam turbine 13 via a line 8. On the other hand, the combustion gas is sent to the gas turbine 11 through the cyclone dust collector 9 and the high-temperature ceramic dust collector 10.

At the time of load reduction, the fluidized material 7 is transferred by a suction pipe 14 to a hopper 15 provided outside the combustion furnace 2.
This is because the gas in the hopper 15 is discharged to the atmosphere through the line 16 by the air release valve 17, and the fluidized material 7 under pressure in the furnace 2 is sucked out together with the gas through the suction pipe 14 and taken out. Done. Hopper 15
The gas in the furnace that has flowed from above flows through the upper part of the hopper 15. On the other hand, the fluid material 7 accumulates at the bottom by gravity drop in the hopper.

[0004]

In the conventional bed height control apparatus shown in FIG. 4, the fluid material is taken out to the hopper outside the combustion furnace by discharging the gas inside the furnace to the atmosphere. Therefore, there has been a problem that the amount of combustion gas sent as a driving gas to the gas turbine decreases, and the thermal efficiency decreases.

An object of the present invention is to provide a pressurized fluidized bed height control apparatus for a combustion furnace which can solve the above problems.

[0006]

Means for Solving the Problems The bed height control apparatus for a fluidized bed of a combustion furnace according to the present invention employs the following means. (1) A combustion furnace having a fluidized bed, a fluidized material hopper, and a fluidized material transport pipe that connects the lower part of the fluidized bed to the fluidized material hopper and moves the fluidized material from the fluidized bed to the fluidized material hopper. In the apparatus for controlling the height of a pressurized fluidized bed of a combustion furnace, a gas suction pipe from the fluid material hopper was connected to a suction side of an ejector, and a discharge side of the ejector was connected to a pipe of combustion gas from the combustion furnace. It is characterized by the following. (2) In the present invention (1), the lower part of the fluidized bed communicates with the fluidized material hopper to transfer the fluidized material from the fluidized bed to the fluidized material hopper. A nozzle, a flow control valve provided on an air inlet pipe from the air source to the air inlet nozzle, a differential pressure gauge for detecting a differential pressure between an upstream side and a downstream side of the fluid material transport pipe, and the differential pressure measurement And a controller for receiving a signal from the meter to control the flow control valve. (3) In the present invention (2), a second air injection nozzle for injecting air flowing in a direction opposite to the flow of the fluid material in the transport tube into the fluid material transport tube; And a shut-off valve provided in each of the air pipes to the air inlet nozzle.

[0007]

In the present invention (1), since the gas suction pipe connected to the fluid material hopper is connected to the suction side of the ejector, the pressure in the fluid material hopper decreases due to the suction force of the ejector, and the combustion takes place. A pressure difference from the inside of the furnace occurs, and a gas in the furnace of the combustion furnace flows in a transport pipe from the combustion furnace to the fluidized material hopper. Along with this, the fluidized material in the combustion furnace is pneumatically transported to the fluidized material hopper together with the furnace gas to control the height of the fluidized bed. The gas in the furnace that has entered the fluidized material hopper enters the combustion gas pipe of the combustion furnace from the discharge side of the ejector via a gas suction pipe, is mixed with the combustion gas discharged from the combustion furnace, and is collected.
It is sent to the downstream gas turbine without loss.

In the present invention (2), in the above-mentioned present invention (1), the differential pressure between the upstream side and the downstream side of the fluid material transport pipe is detected, and the flow rate control valve of the air inlet pipe is controlled based on the detected differential pressure. Then, air is injected from the air injection nozzle into the fluid material transport pipe so that the differential pressure becomes the set predetermined differential pressure. As a result, the density of the fluid flowing through the transport pipe for the fluid is reduced, and the fluid is smoothly pneumatically transported to the fluid hopper. Further, even if the set predetermined pressure difference is reduced,
By reducing the density of the fluid material pneumatically transported in the fluid material transport pipe, a required amount of fluid material is pneumatically transported to the fluid material hopper. Furthermore, the pressure loss of the gas suction pipe between the fluid material hopper and the ejector can be compensated for, thereby reducing the flow rate of the drive fluid for operating the ejector that sucks gas from the fluid material hopper.

In the present invention (3), in the present invention (2), air flowing in the opposite direction to the flow of the fluid material is introduced into the transport pipe for the fluid material from the second air injection nozzle, and this air flow is The resistance to the flow material is partially stopped by the flow of the flow material, or the flow speed is reduced. In the present invention (2), the input air from the air input nozzle and the input air from the second air input nozzle are appropriately input or shut off by a shutoff valve. Thus, the flow rate of the fluidized material conveyed from the combustion furnace to the fluidized material hopper is easily adjusted, and accurate control of the height of the fluidized bed is performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. Reference numeral 2 denotes a combustion furnace in which a pressurized fluidized bed is formed by a fluidized material 7 therein. Air 6 transports coal 4 and limestone 12 as a desulfurization material in the combustion furnace 2 by air. . Air 6 is used as combustion air in combustion furnace 2.
Is supplied to the lower part of the air distribution plate 5 below.

The combustion gas from the combustion furnace 2 is discharged from the upper part of the combustion furnace 2 and supplied to a gas turbine 11 through a cyclone dust collector 9 and a high-temperature ceramic dust collector 10. On the other hand, the heat transfer tube 1 to which the pressurized water 22 is supplied is arranged in the pressurized fluidized bed, and the steam generated in the heat transfer tube 1 is supplied to the steam turbine 13 via the line 8.

Numeral 15 denotes a fluidized material hopper whose upper part is connected to the lower part of the pressurized fluidized bed by a fluidized material transport pipe 14, and sends the fluidized material from the bottom of the hopper 15 to the lower part of the pressurized fluidized bed. A supply pipe 14 'is provided.

Reference numeral 18 denotes an ejector to which steam extracted from the steam turbine 13 through a line 19 having a control valve 20 is supplied as a driving fluid.
Is connected to the upper part of the fluid material hopper 15 via a suction side line 16 having a control valve 17. The discharge side of the ejector 18 is connected to a combustion gas pipe 40 between the cyclone dust collector 9 and the high-temperature ceramic dust collector 10.

In the present embodiment, the pressure in the fluidized material hopper 15 is reduced by the suction force generated in the ejector 18 by the steam from the steam turbine 13, and a differential pressure is generated in the hopper 15 and the combustion furnace 2. Combustion furnace 2 by pressure
The gas in the furnace pneumatically transports the fluidized material 7 to the fluidized material hopper 15. By controlling the control valve 17, the differential pressure is adjusted, and the flow rate of the fluidized material 7 sent from the combustion furnace 2 to the fluidized material hopper 15 is controlled. In this way, the bed height of the fluidized material 7 forming the pressurized fluidized bed is changed according to the load of the combustion furnace 2.
That is, it is possible to control the height of the pressurized fluidized bed to be higher or lower according to the level of the load of the combustion furnace.

The gas inside the furnace, which has pneumatically transported the fluidized material 7 and entered the fluidized material hopper 15, is mixed with the combustion gas that has exited the cyclone dust collector 9 from the discharge side of the ejector 18 via the suction pipe line 16. In addition, the gas in the furnace is not released to the atmosphere, and the thermal efficiency can be increased.

A second embodiment of the present invention will be described with reference to FIG. In this embodiment, the control valve 17 provided in the suction side line 16 in the first embodiment is eliminated, and the surroundings of the fluid material transport pipe 14 and the like are configured as follows.

That is, there is provided an air inlet pipe 22a branched from a pipe of air 6 for transporting the coal 4 and the limestone 14 by air. The air inlet pipe 22a is connected to an air nozzle 25 via a flow meter 23 and a control valve 24. The air nozzle 25
Is opened upward in the fluid material transport pipe 14 at a portion 14a immediately after the suction port of the transport pipe 14 that changes its direction in the vertical direction from the upwardly inclined portion of the fluid material transport pipe 14, Air is supplied in the direction in which the material 7 flows. Reference numeral 26 denotes a differential pressure gauge for detecting a differential pressure between the pressurized fluidized bed and the fluid material hopper 15, that is, a differential pressure between the upstream side and the downstream side of the fluidized material transport pipe 14, and a signal from the differential pressure gauge 26 and the flow meter. The signal 23 is input to the controller 27, and the control valve 24 is controlled by the controller 27 to control the flow rate of the air supplied from the air nozzle 25 to the fluidized material transport pipe 14, thereby maintaining the differential pressure at the target value. It is supposed to.

In the first embodiment, the suction line 1
There was a pressure drop of 6 which required a large flow of steam to operate the ejector 18. Although it depends on the length of the suction side line 16, a steam flow rate that is about twice the gas flow rate in the furnace normally sucked into the fluidized material hopper is required.

In this embodiment, the differential pressure between the upstream side and the downstream side of the fluidized material transport pipe 14 is detected by the differential pressure gauge 26, and the signal is input to the controller 27, and the control valve 24 is controlled based on the signal. Then, a controlled flow rate of air is supplied from the air supply nozzle 25 to the fluidized material transport pipe 14 to maintain the differential pressure at the target differential pressure. In addition, air is injected from the air nozzle 25 in the flowing direction of the fluidized material 7 in the fluidized material transport pipe 14, thereby reducing the density of the fluidized material 7 and promoting the air transport.

Therefore, even if the set target differential pressure is low,
The fluidized material 7 can be smoothly transported to the fluidized material hopper 15, and the flow rate of steam sent to the ejector 18 as a driving fluid can be reduced accordingly.

A third embodiment of the present invention will be described with reference to FIG. This embodiment is different from the second embodiment in that the air inlet pipe 22a is connected to the line 25 'connected to the air nozzle 25 and the second air nozzle 31 downstream of the control valve 24.
The second air nozzle 31 branches obliquely downward at the portion 14a of the fluidized material transport pipe 14 toward the pressurized fluidized bed side, that is, in the direction opposite to the direction in which the fluidized material 7 flows. I am trying to put it in. Further, a setting device 30 is provided for receiving a signal from the controller 27 and a signal from the flow meter 23, and the control valve 24 and the shutoff valves provided on the lines 25 'and 31', respectively, according to the signal from the setting device 30. 28 and 29 are controlled.

[0022] In this embodiment, in the second embodiment, the air is turned in the opposite direction to the flow of fluid material 7 from the second air nozzle 31 is a flow material transport pipe 14 is pneumatically conveyed flow The flow of the material 7 can be stopped or its flow rate can be reduced. When the rate of change of the load reduction of the combustion furnace 2 is large and the flow rate of the fluidized material 7 to the fluidized material hopper 15 is increased, the shutoff valve 29 is closed and the air from the second air nozzle 31 is closed by a signal from the setter 30. Cut off the input of
At the same time, the shut-off valve 28 is opened to supply air from the air nozzle 25, and the flow rate of the supplied air is controlled by the control valve 24 in accordance with a signal from the setter 30. Thus, the differential pressure between the upstream side and the downstream side of the fluidized material transport pipe 14 is maintained at the target value as in the second embodiment, and the fluidized material 7 having a predetermined flow rate set by the setting unit 30 is supplied to the fluidized material hopper. 15 by air.

On the other hand, when the rate of change of the load reduction of the combustion furnace 2 is small and the flow rate of the fluidized material 7 to the fluidized material hopper 15 is reduced, the shut-off valve 29 of the line 31 ′ is opened by the signal of the setter 30. The shutoff valve 28 of the line 25 ′ is closed, and air is injected from the second air nozzle 31 in a direction opposite to the flow of the fluid 7, and the injection of air from the air nozzle 25 is shut off. At the same time, the flow rate of air supplied from the second air nozzle 31 is controlled by the control
Control by controlling. As a result, as in the second embodiment, the differential pressure between the upstream side and the downstream side of the fluidized material transport pipe 14 is maintained at the target value, and the fluidized material having the predetermined flow rate set by the setting device 30 is easily flown. Pneumatic transportation to the material hopper 15 is possible.

Therefore, in this embodiment, the bed height of the pressurized fluidized bed can be easily and accurately controlled.

In the above embodiment, the bed height of the pressurized fluidized bed is controlled. However, the present invention can be used for controlling the bed height of a normal pressure fluidized bed.

[0026]

According to the first aspect of the present invention, in-furnace gas for pneumatically transporting a fluid material forming a fluidized bed to a fluid material hopper according to the load of the combustion furnace is supplied from the combustion furnace to a gas turbine or the like. Combustion gas can be recovered and the thermal efficiency can be improved.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the differential pressure between the upstream side and the downstream side of the fluidized material transport pipe is maintained at a small predetermined value. The required flow rate of the fluid material can be pneumatically transported to the fluid material hopper, and the flow rate of the working fluid required for driving the ejector can be reduced, and the fluid material can be efficiently transported to the fluid material hopper by pneumatic transport.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, the flow rate of pneumatically transporting the fluidized material to the fluidized material hopper can be easily controlled to a predetermined value. And the bed height of the fluidized bed can be easily and accurately controlled.

[Brief description of the drawings]

FIG. 1 is a system diagram of a first embodiment of the present invention.

FIG. 2 is a system diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a main part of a third embodiment of the present invention.

FIG. 4 is a system diagram of a conventional bed height control device for a pressurized fluidized bed of a combustion furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat transfer tube 2 Combustion furnace 9 Cyclone dust collector 10 High temperature ceramic dust collector 11 Gas turbine 13 Steam turbine 14 Fluid material transport pipe 15 Fluid material hopper 16 Suction side line 17 Control valve 18 Ejector 19 Steam line 20 Control valve 22a Air Input pipe 23 Flow meter 24 Control valve 25 Air nozzle 26 Differential pressure gauge 27 Controller 28 Shutoff valve 29 Shutoff valve 30 Setting device 31 Second air nozzle

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuo Hayata 5-717-1 Fukabori-cho, Nagasaki-shi Inside Nagasaki Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Yoshihisa Arakawa 1-1-1, Akunoura-cho, Nagasaki-shi Mitsubishi Heavy Industries, Ltd. (72) Inventor, Yoshinori Kobayashi 1-1, Akunoura-cho, Nagasaki-shi Mitsubishi Heavy Industries, Ltd. Inside Nagasaki Shipyard, Ltd. (72) Inventor Hiroshi Akiyama 1-1, Akunoura-cho, Nagasaki-shi Mitsubishi Heavy Industries, Ltd. Inside the shipyard (56) References JP-A-5-52306 (JP, A) JP-A-5-141619 (JP, A) JP-A-5-25111 (JP, U) JP-A-4-63906 (JP, U) ) JK 2-109113 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F23C 11/02 305 F23C 11/02 308

Claims (3)

(57) [Claims] 1. A combustion furnace having a fluidized bed, a fluidized material hopper, and a fluidized material transport pipe that connects a lower portion of the fluidized bed to the fluidized material hopper and moves the fluidized material from the fluidized bed to the fluidized material hopper. In the apparatus for controlling the height of a fluidized bed of a combustion furnace provided with: a gas suction pipe from the fluid material hopper is connected to a suction side of an ejector, and a discharge side of the ejector is connected to combustion gas piping from a combustion furnace. A bed height control device for a fluidized bed of a combustion furnace, characterized in that: 2. An air injection nozzle provided in the middle of a fluid material transport pipe for connecting the lower portion of the fluidized bed and the fluidized material hopper to move the fluidized material from the fluidized bed to the fluidized material hopper. A flow control valve provided in an air inlet pipe to the air inlet nozzle, a differential pressure gauge for detecting a differential pressure between the upstream side and the downstream side of the fluid material transport pipe, and a signal from the differential pressure gauge are input. The bed height control apparatus for a fluidized bed of a combustion furnace according to claim 1, further comprising a controller for controlling the flow rate control valve. 3. A second air injection nozzle for injecting air flowing in a direction opposite to the flow of the fluid material in the transport tube into the fluid material transport tube, and a second air injection nozzle and the second air injection nozzle. The bed height control device for a fluidized bed of a combustion furnace according to claim 2, further comprising a shutoff valve provided in each of the air pipes.