JP3117274B2 - Dust collection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust collecting apparatus used for removing dust having a high dust content at a high temperature and a high pressure, such as a pressurized fluidized-bed boiler and a gasification filter.

[0002]

2. Description of the Related Art A combined cycle power plant that drives high pressure and high temperature combustion exhaust gas generated in a pressurized fluidized bed boiler to a gas turbine to drive the gas turbine provides high efficiency power generation, but prevents gas turbine wear. Clean exhaust gas is indispensable from above, and usually dust (combustion ash, soot) in combustion exhaust gas
A dust collecting device is installed to remove the dust in advance.

In this type of combined cycle power plant, as shown in FIG. 4, a combustion exhaust gas 32 generated in a pressurized fluidized bed boiler 31 is combusted in a cyclone dust collector 34 utilizing centrifugal force through a duct 33. Most of the exhaust gas dust is collected and removed, but the gas turbine side is required to be clean exhaust gas, and is made of a porous hollow cylindrical porous solid having air permeability. , Pressure-resistant precision dust collector 35
After that, the gas is sent to the gas turbine 36.

The dust collected by the cyclone dust collecting device 34 and the precision dust collecting device 35 is collected by the dust collecting device 3.
4a and 35a , the flue gas 3 which has been collected and discharged to the outside of the upper system, and after the gas turbine 36 has been driven.
7, heat is recovered in various heat exchangers (not shown) and released to the atmosphere.

FIG. 5 shows a conventional precision dust collecting apparatus according to a "dust removing apparatus provided with a diffuser" disclosed in Japanese Patent Publication No. 22690/1990 used for the combined cycle power plant. This will be described. A plurality of unit filter tubes 22a made of a gas-permeable porous solid are connected to each other in the container 21 to form a single filter tube group. It is fixed in the container 21. The dust-containing combustion gas 32 enters the filter tube 22 through the gas inlet hole 24, and when passing through the filter tube 22 from the inner surface to the outer surface, dust 25 in the exhaust gas adheres to and separates from the inner surface of the filter tube 22. The dust 25 is discharged out of the system collected at the lower part of the container 21. On the other hand, the exhaust gas that has passed through the outer surface of the filter tube 22 and has been purified is sent to the gas turbine through an outlet duct 26 opening on the side wall of the plurality of containers 21 and a collective discharge duct 27 serving as a gas outlet.

A backwash nozzle 11 for introducing a backwash air flow is provided in the outlet duct 26, and the backwash air flow sent from the compressor 12 is transferred from the backwash nozzle 11 to the container via a common pipe 12a and a valve 12b. A constant amount of airflow is blown into the inside of the filter tube 21 for a certain period of time (called a backwashing period time), and dust adhering to the inner surface of the filter tube 22 is separated into the filter tube 22 to collect dust. Repeat the action.

[0007] A diffuser having a divergent angle is formed in the outlet duct 26 between the wall of the container 21 and the backwash nozzle 11 in order to recover the pressure of the air flow, or the outlet duct 26 has a diffuser shape. I have.

On the other hand, the opening and closing of the valve 12b for ventilating and stopping the backwash air flow in front of the plurality of backwash nozzles 11 is performed at regular intervals in a top-to-bottom order.
Therefore, the exhaust gas 32 is discharged to the outside of the dust collector system through an outlet hole other than the outlet duct 26 into which the backwash air is blown into the container 21.

[0009]

In the above-mentioned conventional dust collecting apparatus, the outlet duct 26 has a diffuser shape and has a gently widened front end for pressure recovery. For this purpose, the position of the backwash nozzle 11 must be installed at a position far away from the container wall, and the kinetic energy of the backwash airflow having a pressure 2-3 times higher than that in the container is effectively used. I can't get it.

In order to obtain an efficient diffuser effect, the distance of the horizontal portion of the outlet duct 26 is increased, and the cost is increased. In addition, the installation of piping and the like hinders the space and the like, and the degree of freedom in layout is greatly limited.
In addition, when replacing nozzles, maintenance space is limited, and workability is deteriorated. In addition, at the time of backwashing, it is expected that the flow of the backwash airflow is restricted by the throttle of the diffuser, and that the pressure loss increases.

Further, the properties of the dust in the combustion exhaust gas 32 generated from the pressurized fluidized bed boiler 31, that is, its content, particle size and particle size distribution vary with the equipment scale and operating conditions and vary with time. In the case of backwashing using a high-pressure airflow injected from the backwash nozzle 11, dust adhering to the inner surface of the filter tube 22 may not be sufficiently removed in response to fluctuations in the properties of the dust.

An object of the present invention is to provide a dust collecting apparatus which can solve the above problems.

[0013]

According to the present invention, a group of filter cylinders made of a gas-permeable porous solid are housed in a container having a dust-containing gas inlet and a clean gas outlet, and the dust-containing gas is introduced through the dust-containing gas inlet. The following measures were taken in a dust collecting apparatus in which was supplied to the inside of a filter tube to take out a clean gas from the outside of the filter tube and to guide it to the clean gas outlet. (1) discharge duct of the clean gas outlet opening into the vessel wall, and includes a blown injector formula backwash nozzle backwash air flow opening toward the group of the濾筒provided in the exhaust duct, the reverse The backwash air flow is expanded in front of the washing nozzle opening.
The flow spreading plate is arranged . (2) a discharge duct at a clean gas outlet, a backwashing device provided in the discharge duct and blowing a backwash airflow toward the group of filter tubes, and a backwash fluid flow having a higher pressure than the backwash air flow. A fluid supply device for blowing toward the group of the filter tubes is provided.

[0014]

According to the present invention (1), an injector type backwash nozzle is employed, and a high-pressure air flow of, for example, two to three times the inner pressure of the container, as in the conventional diffuser type dust collecting apparatus. Is blown at a high speed, for example, at a speed close to the speed of sound, toward the group of filter tubes in the container, so that the attachment duct on the inner surface of the filter tube is effectively removed.

Further, since the backwash nozzle of the injector type is employed, the position of the backwash nozzle in the discharge duct of the clean gas outlet, in other words, the flow of the backwash air flow, is different from that of the conventional diffuser type. The jetting position can be installed at a position close to the vessel wall, which makes more effective use of the kinetic energy of the backwash air flow, increases the detachment effect of the attached dust, and accordingly, the required amount of the backwash air flow Is achieved. In addition, in front of the opening of the backwash nozzle,
By installing a spreading plate that expands the washing air flow,
Is extended along the length of the filter tube, and backwashing is performed along the length of the filter tube.
And the backwash air flow reaches the filter tube, etc.
Shock waves can be reduced. In addition, the discharge duct can be shortened by installing the backwash nozzle near the container wall. As a result, the initial cost and the running cost of the facility related to the backwash can be significantly reduced, and the apparatus can be downsized.

In the present invention (2), when the properties of the dust-containing gas and the like fluctuate and dust adhered to the wall of the filter tube cannot be sufficiently removed by the backwashing airflow in the backwashing airflow, By blowing a backwash fluid stream having a higher pressure than the backwash air stream from the fluid supply device, dust adhering to the inner surface of the filter tube can be sufficiently removed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In this embodiment, as in the dust collecting apparatus shown in FIG. 5, a plurality of unit filter tubes made of a gas-permeable porous solid are connected to form one filter tube, and a plurality of groups of these filter tubes are housed in a container. It relates to a dust device, and includes a flue gas 32, a container 21, a filter tube 22, a unit filter tube 22a, a sealing tube plate 23a, a reinforcing tube plate 23b, a gas inlet hole 24, dust 25, a collective discharge duct 27, and a compression. The configurations of the machine 12, the common pipe 12a, and the valve 12b are the same as those of the dust collecting apparatus shown in FIG. 5, and a description thereof will be omitted.

In the present embodiment, the plurality of outlet ducts 26 opened to the side wall of the container 21 and connecting the inside of the container 21 and the collecting and discharging duct 27 form a tubular body having a constant cross-sectional shape. Inside, an injector 13 opening toward the inside of the container 21 is provided at a position close to the wall of the container 21, and is connected to the common pipe 12 a via the valve 12 b in the injector 13 and to the filter tube 22 in the container 21. A backwash nozzle 11 capable of blowing a backwash air flow toward the backwash nozzle is provided. Also,
The injector 13 is provided with a hole 13a that opens upward. A flow expansion plate 14 for expanding the backwash air flow is disposed in front of an opening of the injector 13 toward the inside of the container 21. Further, between the compressor 12 and the common pipe 12a, a tank 29 for storing the compressed air from the compressor 12 is provided. Each of the outlet ducts 26 connects each space in the container 21 formed between the sealing tube sheet 23a and the reinforcing tube sheet 23b, and the adjacent reinforcing tube sheet 23b to the collective discharge duct 27. It has become.

In this embodiment constructed as described above, the flue gas 32 enters the filter tube 22 through the gas inlet hole 24, and when passing from the inner surface to the outer surface of the gas permeable filter tube 22, the exhaust gas 32 The dust 25 adheres to the inner surface of the filter tube 22, while the clean exhaust gas from which the dust 25 has been removed is sent to the gas turbine through a plurality of outlet ducts 26 and a collective discharge duct 27.

In the above state, dust collection is performed and clean exhaust gas is sent to the gas turbine. Backwashing of the filter tube 22 is performed as follows. That is, the valve 12b is sequentially opened for a fixed time (referred to as a backwashing time) at regular time intervals (referred to as a backwashing time). To the group, container 21
High-pressure air having a pressure 2-3 times higher than the internal pressure is jetted at a high speed close to the speed of sound. This high-pressure air flow sucks air in the outlet duct 26 from the hole 13 a of the injector 13 and
The air in the outlet duct 26 around the high-pressure airflow is sucked to form a backwash airflow into the container 21, and a reverse pressure higher than the internal pressure of the container 21 is applied from the outer surface of the filter tube 22 to the inside.
As a result, the dust 25 adhering to the inner surface of the filter
Is separated from the inner surface, falls to the lower part of the container 21, and is periodically paid out of the system. For example, the backwash cycle time is selected to be about 10 minutes, and the backwash time is selected to be about 0.5 to 1.0 second.

In the plurality of outlet ducts 26, the backwash air flow is generated sequentially during the backwash time for each backwash cycle time, and the backwash is performed over the entire length of each filter tube 22.

Further, the backwash air flow is spread in the length direction of the filter tube 22 by the flow spreading plate 14 provided in front of the injector 13, and the backwash is performed uniformly in the length direction of the filter tube 22. And the shock wave exerted by the backwash airflow on the filter tube 22 and the like can be reduced.

In this embodiment, as described above, the injector 1
Backwashing of the filter tube 22 can be performed by a backwashing airflow formed by a high-pressure airflow ejected from the backwashing nozzle 11 in the inside 3. In addition, since the injector 13 provided with the backwash nozzle 11 is provided in each outlet duct 26, the injector 13 can be arranged at a position close to the side wall surface of the container 21. The backwashing of the filter tube 22 can be performed effectively by using the kinetic energy possessed more effectively, and therefore, the amount of required backwash airflow can be reduced, and the discharge duct 26 is connected to the diffuser. Can be significantly shortened, as compared with the case where.

The backwash air flowing at a high speed is supplied to the expansion plate 1.
4, the backwash can be uniformly performed in the longitudinal direction of the filter tube 22 and the shock wave exerted by the backwash airflow on the filter tube 22 and the like can be reduced.

In the first embodiment, the expansion plate 14 is provided in front of the injector 13, but the expansion plate 14 may be tilted vertically instead of the expansion plate 14. Functions and effects similar to those of the plate 14 can be obtained.

A second embodiment of the present invention will be described with reference to FIG. This embodiment is a modification of the first embodiment as follows. That is, the ejector provided in each outlet duct 26 was omitted, and only the backwash nozzle 11 was provided. Further, a stop valve 28a is provided in the common pipe 12a connecting each backwash nozzle 11 and the tank 29, and a tank 42 having a higher pressure than the tank 29 and a compressor 41 for supplying compressed air to the tank 42 are provided. The tank 42 and the downstream side of the valve 28a of the common pipe 12a are connected by a pipe 43 having a stop valve 43a. The pressure between the inner surface and the outer surface of the filter tube 22 and the pressure difference are detected by a pressure gauge (not shown), whereby the stop valves 28a and 43a are controlled.

The nature of the dust adhering to the inner surface of the filter tube 22 fluctuates depending on the operating conditions of the dust-containing gas source to the filter tube 22, and if the dust adhering to the inner surface of the filter tube 22 is insufficiently removed for a period of time. May be. As described above, if the detachment of the adhered dust is not sufficient, fine particles enter the porous portion of the filter tube 22, or block the gas flow path, and the gas passage area of the filter tube 22 decreases, The passing pressure between the inside and outside of the filter tube 22 wall increases, and the pressure loss increases.

FIG. 3 shows the operation elapsed time during the operation of the dust collector according to the present embodiment, the X axis being the operation time, the Y axis being the pressure difference between the inner wall surface and the outer wall surface of the filter tube 22, and the high pressure air flow from the backwash nozzle. as container 21 internal pressure when the injection is obtained by displaying the change of these values, the pressure difference between the inside and outside surfaces of濾筒22 the separation of the adhering dust is deteriorated increases from P ₂₁ to P _22, At the same time the vessel 21 the pressure at the time of injecting high-pressure air flow from the backwash nozzles 11 also increases from P ₁₁ to P _12. If this state continues, the detachment of the dust adhering to the inner surface of the filter tube 22 decreases at an accelerated rate, and eventually the operation and operation as a dust collecting device become impossible.

In this embodiment, the pressure difference is P₁₂Or the above
Container pressure is P_{twenty two}Pressure gauge etc. not shown
To close the stop valve 28a and open the one-way stop valve 43a.
Switch high pressure air from tank 42
Supply to backwash nozzle 11 and squirt from backwash nozzle 11
The backwashing power is increased by the
And therefore the pressure difference P₁₂Is P₁₁
The pressure P in the container _{twenty two}Is P_{twenty one}To the initial value
To recover.

At the time when the pressure difference and the pressure in the container have been restored to the initial values, the stop valves 28a and 43a
Switching between open and closed operation by the conventional operation method. Therefore, the dust collecting device can be operated stably and continuously.

Further, the compressor 31 and the tank 32 for supplying the high-pressure air, which are added in the present embodiment, are used for a short time, so that these facilities can be reduced in size.

[0032]

According to the first aspect of the present invention, since the injector type backwash nozzle is provided in the discharge duct of the clean gas outlet, the backwash nozzle can be installed at a position close to the container wall. In addition, the kinetic energy of the high-pressure backwash air flow is effectively applied to the outer surface of the filter tube, and the duct attached to the inner surface of the filter tube can be easily separated, so that the backwash effect is effective, and The flushing flow rate can be reduced.
In addition, the backwash air flow is spread in front of the backwash nozzle opening.
The backwash air flow is reduced by the length of the filter
Backwashing is performed uniformly along the length of the filter tube
And the shock wave that the backwash air flow exerts on the filter tube etc.
Can be eased. Further , the length of the discharge duct can be shortened because the backwash nozzle can be installed at a position close to the container wall. Therefore, it is possible to reduce the size of the backwash facility and to reduce the initial cost and running cost.

According to a second aspect of the present invention, in addition to the backwashing device for removing dust in the dust-containing gas adhering to the wall of the filter tube, a backwash having a higher pressure than the backwash air flow by the backwashing device is provided. By adding a fluid flow supply device, when the property of dust in the dust-containing gas sent to the dust collection device fluctuates, the poor detachment of dust attached to the inner surface of the filter tube, that is, when the backwashing performance deteriorates The backwashing power is increased by blowing a high-pressure backwash fluid flow from the added fluid supply device, completely removing dust adhering to the inner surface of the filter tube and removing fine particles that have entered the porous channel. And a stable long-term continuous operation of the dust collecting device can be realized. Still further, since the added fluid supply device is used only for a short period of time, it can be made small-scale equipment and inexpensive.

[Brief description of the drawings]

FIG. 1 is a sectional view of a dust collecting apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a dust collecting apparatus according to a second embodiment of the present invention.

FIG. 3 is a graph showing changes in the pressure difference between the inner and outer walls of the filter tube and the internal pressure of the container during operation of the dust collecting apparatus according to the second embodiment.

FIG. 4 is a system diagram of a combined power generation system of a pressurized fluid bed boiler gas turbine.

FIG. 5 is a sectional view of a conventional precision dust collecting apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Backwash nozzle 12 Compressor 13 Injector 14 Spread plate 21 Container 22 Filter tube 22a Filter tube unit tube 24 Gas inlet hole 25 Dust 26 Exit duct 27 Collecting discharge duct 29 Tank 32 Combustion exhaust gas 41 Compressor 43 Tank

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tetsuya Ueda 1-1, Akunouramachi, Nagasaki City Inside Nagasaki Shipyard, Mitsubishi Heavy Industries, Ltd. (56) References JP-A-64-38120 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) B01D 46/00-46/54

Claims (2)

(57) [Claims] 1. A group of filter cylinders made of a gas-permeable porous solid is accommodated in a container having a dust gas inlet and a clean gas outlet, and the dust gas is supplied from the dust gas inlet to the inside of the filter cylinder. In a dust collecting device for taking out a clean gas from the outside of the filter tube and guiding the gas to the clean gas outlet, a discharge duct of the clean gas outlet opening to the container wall, and a group of the filter tubes provided in the discharge duct. An injector-type backwash nozzle that opens toward the side and blows backwash airflow, and the opening of the backwash nozzle is provided .
A dust collecting device, wherein a spreading plate for expanding the backwash air flow is disposed in front of the dust collecting device. 2. A group of filter tubes made of a gas- permeable porous solid is accommodated in a container having a dust gas inlet and a clean gas outlet, and the dust gas is introduced from the dust gas inlet to the inside of the filter tube. In a dust collecting device that supplies and removes clean gas from the outside of the filter tube and guides the clean gas to the clean gas outlet, a discharge duct of the clean gas outlet, a backwash air flow provided in the discharge duct and directed toward a group of the filter tubes. A dust collecting apparatus comprising: a backwashing device for blowing in; and a fluid supply device for blowing backwashing fluid flow having a pressure higher than that of the backwashing airflow toward the group of the filter tubes.