JPH07256036A - Backwashing device for ceramic filter - Google Patents

Abstract

PURPOSE:To provide a backwashing device for a ceramic filter equipped with a back wash valve which can shorten the operation time of backwashing. CONSTITUTION:A honeycomb type element 4 and a cylinder type element 5 are placed in a can 1, which is divided into a space for high temperature dust- containing gas and more than one space for clean gas by these ceramic filter blocks, etc. A back wash nozzle 13 directed to a filter element is placed in the space for clean gas to backwash each filter block periodically. Two back wash valves 11, 12, which control backwashing gas, are arranged in series in a backwashing gas introduction pipe installed in each filter block and operated to be opened and closed alternately in the backwash cycle of each block.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backwashing device for a dust remover which removes hot dust-containing gas by using a cylindrical element or a honeycomb element mainly made of a porous ceramics body.

[0002]

2. Description of the Related Art In a ceramic filter dust remover for a pressurized fluidized bed boiler, in which a plurality of cylindrical elements or honeycomb elements made of porous ceramics are arranged in a can, the elements adhere to the dust-containing gas side surface. In order to remove the dust, it is necessary to raise the pressure on the clean gas side for a very short period of time, and at that time, a so-called backwashing device that removes the dust by causing a gas flow in the direction opposite to that in normal filtration is required. The dust removal efficiency of the filter is maintained by this.

Therefore, conventionally, as shown in FIG. 4, a necessary number of backwash nozzles 13 are provided in a unit backwash system for each filter block, and a backwash valve 10 for controlling backwash air upstream thereof.
Is provided, and cyclic backwashing is performed within the backwashing interval (about several minutes) determined by the number of ceramic filter units for pressurized fluidized bed boiler in the unit and the backwashing filter block per unit.

During backwashing, the pressure on the clean gas side must be raised in a very short time in order to increase its effect.
Actually, the specific method is selected and used in consideration of the backwash air temperature, the valve type, the material, and the valve driving method.

[0005]

The backwash valve for controlling the backwash gas of the conventional dust remover shown in FIG. 4 causes a gas flow in the filter element in the direction opposite to that in the normal filtration, and dust is generated. The valve can be opened and closed instantly to effectively dispel it, and the backwash cycle itself must be performed on the order of a few seconds, but if one valve is used to perform the opening and closing operation, the opening and closing operations will be particularly effective. The valve receives a large axial force when shifting to. Further, this causes a fatigue damage to the main part of the valve by applying an excessive axial force, and thus the possibility of shortening the life of the valve is a serious problem.

The present invention overcomes these problems and the stagnation in the improvement of the backwashing effect resulting therefrom, and can shorten the opening / closing time without applying an excessive axial force to the opening / closing valve. It is an object of the present invention to provide a backwashing device for a ceramic filter including the above.

[0007]

The present invention comprises a plurality of filter blocks composed of a plurality of filter elements made of porous ceramics and a partition plate, and a space for a high temperature dust-containing gas including a dust hopper in a can and a plurality of spaces. A backwashing device in a dust removing device partitioned into a clean gas space, wherein the backwashing device for a ceramic filter is configured to perform backwashing periodically by a backwash nozzle for each filter block. Therefore, a configuration is employed in which two backwash valves for controlling the backwash gas are arranged in series in the backwash gas introduction pipe provided for each filter block.

The operation of the backwash device for a ceramic filter according to the present invention thus constructed is as follows. By installing two backwash valves provided in the backwash gas introduction pipe in series, that is, by duplicating them in tandem, one valve opens during backwash in one cycle. One operation is to close or to close, and it is possible to shorten the opening / closing time by enabling the front and rear valves to open and close the backwash gas flow path as a set without the two valves operating simultaneously. Can be done.

That is, referring to FIG. 2, which is an explanatory view of the sequence of the linked operation between the backwash air front and rear valves, in the pattern A, when the backwash cycle starts, first, the backwash air front valve changes from the fully closed position to the fully open position. However, at this time, the valve remains fully open after backwashing air and does not move. Next, the backwash gas flow path must be closed to complete the backwash.At this time, the backwash air post-valve moves from the fully open position to the fully closed side, and one backwash air front valve is fully opened. It does not move as it is. Then, this state of being kept is held until the next backwash cycle comes.

Pattern B shows the movement of the valve during this next backwash cycle. First, since the backwashing gas passage is opened, unlike the previous time, the fully closed backwash air post-valve moves to the open side and the backwash air pre-valve does not move. To close the backwash gas flow path to finish the backwash, move the fully opened backwash air front valve to the fully closed direction.At this time, the backwash air post valve is fully opened. It will be held until the backwash cycle comes.

FIG. 3 shows the relationship between the valve opening and the backwash time. The target value of the backwash time is about 0.5 seconds. In this way, by duplicating the valves and sharing the opening and closing operations with each other, effective backwashing becomes possible, the efficiency of the dust removing device increases, and the amount of unnecessary backwashing air decreases, so that the high pressure air compressor Power consumption is reduced, which in turn improves the plant efficiency of the pressurized fluidized bed boiler.

Each of the two backwash valves provided in each of the backwash gas introduction pipes is constructed so that the opening and closing operations thereof are preferably alternately alternately performed in the backwash cycle of each block. Good to do. By thus duplicating the valves and sharing the opening and closing operations, the axial load of the valves is significantly reduced compared to the conventional method in which the opening and closing operations are performed by one valve. Wear of rotating shafts, bearings, valve bodies, etc., and fatigue due to stress are reduced, prolonging life.

Further, the backwash valve provided in the backwash device according to the present invention may be of an on-off type which is operated by fluid pressure such as air pressure or hydraulic pressure. In this way, by making the backwash valve into an on-off valve type having a pneumatically or hydraulically actuated actuator, the desired operation can be effectively performed as a backwash valve that has a large opening and closing speed and is durable.

Furthermore, in the backwashing apparatus according to the present invention, each two backwashing valves provided in the backwashing gas introduction pipe are provided.
It is preferable that the timing of starting each operation can be relatively adjusted by a timer. By providing a timer in the control circuit of the backwash valve actuator in this way, it is possible to adjust the valve opening / closing operation timing, which makes it possible to set the backwash cycle to the optimum time and backwash the ceramic filter. It becomes an efficient device.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the backwash air system diagram of the ceramic filter for a pressurized fluidized bed boiler of FIG. In the present embodiment, the filter block has a total of 4 blocks, that is, two blocks in the honeycomb type element 4 on the upper side of the can body 1 and two blocks in the cylindrical type element 5 on the lower side. Therefore, the backwash air system 9 is divided into four series,
Each of them is provided with a set of backwash valves including a backwash air pre-valve 11, a backwash air post-valve 12, and a manual bypass valve upstream of the necessary number of backwash nozzles 13 for the block.

A high-pressure air receiver 14 is provided upstream of these backwash air systems 9, and normally, a ceramic filter for a pressurized fluidized bed boiler is composed of 2 to 3 units / unit, and therefore is connected to each filter. The high-pressure air compressor 15 is located further upstream thereof and includes two spare machines.

The operation of the backwash air system 9 having such a structure is performed as follows. That is, the high-temperature dust-containing gas that has entered from the dust-containing gas inlet 2 in the upper part of the can body 1 of the ceramic filter for a pressurized fluidized bed boiler installed almost vertically is composed of the honeycomb type element 4 of the porous ceramic body. The upper two filter blocks make up a part of it, and the remaining high-temperature dust-containing gas is divided into two parts by the upper partition tube plate 6, the lower partition tube plate 7 and the cylindrical element 5 divided by the inner cylinder outer cylinder partition plate. Dust is removed by the filter block.

The clean gas that has passed through each element is taken out to the outside by each clean gas outlet pipe 8 and is joined to the gas turbine in the downstream. The dust removed by each filter block falls into the dust hopper at the lower part on the high temperature dust containing gas side and is discharged from the dust hopper outlet 3.

However, the dust adhering to the dust-containing gas side of each element does not necessarily fall from itself, and a normal reverse gas flow is generated, that is, pressure waves of high pressure air in the reverse direction are very small. It is necessary to raise the gas pressure by applying a short time (about 0.5 seconds) to remove the dust adhering to the dust-containing gas side, that is, backwashing.
This backwash is usually performed cyclically in sequence for each unit block, and the backwash interval is planned to be several minutes.

As in the present embodiment, two backwash air valves are connected in series, each of which is a front valve 11 and a rear valve 12, so as to be doubled, so that one backwash valve is used for backwashing in one cycle. The operation is either open or close, and 2
It is possible to shorten the opening / closing time by enabling the back and forth valves as a set to open and close the backwashing gas flow channel without operating the two valves at the same time.

In this way, double backing of valves allows the opening and closing operations to be shared by each other, which enables effective backwashing, which increases the efficiency of the dust remover and reduces the amount of wasted backwashing air. Power consumption of the compressor is reduced, which in turn improves plant efficiency of the pressurized fluidized bed boiler.

Further, as described above, by doubling the valves and sharing the opening / closing operations, the axial load on the valves is significantly reduced as compared with the conventional system in which the opening / closing operations are performed by one valve. As a result, the rotating shaft of the backwash air valve, the bearing, the valve body, and the like are less worn and fatigue due to stress is reduced, and the life is extended.

Further, by providing a timer in the control circuit of the valve actuator, the operation timing of opening and closing the valve can be adjusted, so that the backwash cycle can be set to the optimum time and the improvement is promoted.

Further, by making the backwash valve an on-off valve type having an actuator operated by air pressure or hydraulic pressure, the above-mentioned improving action is promoted as a backwash valve having a large opening and closing speed and having durability.

[0025]

As described above, the following effects can be obtained by constructing and operating the backwashing device for the ceramic filter as in the present invention.

(1) The backwash air valve is doubled in tandem,
In one backwash, open as one valve operation,
It is possible to shorten the opening and closing time by performing one operation of closing. As a result, the backwashing effect is improved, and the power consumption of the high-pressure air compressor is reduced because the backwashing air volume is reduced, and the efficiency of the dust remover and thus the plant efficiency of the pressurized fluidized bed boiler are improved.

(2) As described above, the valve is doubled and the opening / closing operation is shared, so that the axial load of the valve is significantly reduced as compared with the conventional method in which the opening / closing operation is performed by one valve. As a result, the rotating shaft of the backwash air valve, the bearing, the valve element, and the like are less worn and fatigue due to stress is reduced, which prolongs the life.

(3) Since it is possible to adjust the valve opening / closing operation timing, the backwash cycle can be set to an optimum time, and the effect of the above (1) is promoted.

[Brief description of drawings]

FIG. 1 is an air system diagram in a backwash device for a ceramic filter for a pressurized fluidized bed boiler according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the sequence of linked operation between backwash air front and rear valves in the backwash device of the present invention.

FIG. 3 is a diagram showing a target value of a required time for backwashing by the backwashing apparatus of the present invention.

FIG. 4 is a backwash air system diagram in a conventional backwash device for a ceramic filter for a pressurized fluidized bed boiler.

[Explanation of symbols]

 1 Can body 2 Dust-containing gas inlet 3 Dust hopper outlet 4 Honeycomb type element 5 Cylindrical element 6 Upper partition tube plate 7 Lower partition tube plate 8 Clean gas outlet pipe 9 Backwash air system 11 Backwash air front valve 12 Backwash air Rear valve 13 Backwash nozzle 14 High pressure air receiver 15 High pressure air compressor

Claims (4)

[Claims] 1. A plurality of filter blocks composed of a plurality of filter elements housed in a can body installed almost vertically and a partition plate for partitioning or supporting these filter blocks, wherein the can body is A backwashing device for a ceramic filter in a dust removing device using a porous ceramic body, which is partitioned into a space for high-temperature dust-containing gas including a dust hopper and a space for a plurality of clean gases, wherein A backwashing device is installed inside the clean gas outlet pipe connected to the space or inside the upstream space thereof, and the backwashing nozzle is installed toward the filter element, and the backwashing device periodically backwashes the filter element for each filter block. In the above, two backwash valves for controlling the backwash gas are arranged in series in the backwash gas introduction pipe provided for each filter block. A backwash device for a ceramic filter, which is characterized in that 2. The backwash device for a ceramic filter according to claim 1, wherein each of the two backwash valves performs the opening / closing operation alternately in the backwash cycle of each block. 3. The backwash device for a ceramic filter according to claim 1, wherein the backwash valve is a fluid pressure operated on / off type valve. 4. The backwash valve for a ceramic filter according to claim 1, wherein each of the two backwash valves is configured such that a timing of starting operation of each of the two backwash valves can be relatively adjusted by a timer. apparatus.