JP2000334238A - Method and device for back washing filter type dust collecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely execute back washing with a small amount of back washing gas. SOLUTION: Bag shaped or box shaped filter fabrics 5a, 5b, 5c and 5d are mounted at a cell plate 3 provided in a casing by opening its inside above the cell plate. Backwash gas jetting headers 24a, 24b, 24c, 24d and 24e are arranged above the cell plates 3 in accordance with the upper end open part 6 of each filter fabric to enable elevating drive by fluid pressure cylinders 25a, 25b, 25c, 25d and 25e. When one filter fabric is backwashed, a corresponding backwash gas jetting header is fallen to block the upper end open part 6 of the filter fabric, and a solenoid valve for jetting in mid-way of a backwashing line 29 is opened, and the gas 16 for backwashing is sprayed to the inside of the filter fabric to blow of the dust 8 stuck at the outside of the filter fabric. Then the backwash gas jetting header is raised after closing the solenoid valve for jetting. The series of an operation is executed by the instruction from a control device 39. This work is executed for every filter fabrics 5a, 5b, 5c and 5d in order.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter type dust collector for filtering dust collected on a dust collecting element from a filter type dust collector such as a bag filter. The present invention relates to a backwashing method and apparatus.

[0002]

2. Description of the Related Art A filter-type dust collector collects dust in a mixed gas by passing a mixed gas of dust and gas through a bag-shaped or box-shaped dust collecting element made of a porous material. This is a type of dust collector that separates from gas. One of such filter-type dust collectors is a type of dust collector in which the exhaust gas discharged from an incinerator for incineration of refuse etc. FIG. 4 used as an exhaust gas treatment device for collecting dust
A bag filter 1 as shown in (a), (b) and (c) is known.

[0003] The above-mentioned bag filter 1 is shown in FIGS.
(C) As shown schematically in an example, a cell plate 3 having a large number of circular filter cloth mounting holes 4 arranged vertically and horizontally and opened at the upper end position of a casing 2 extending in the vertical direction is hermetically attached. The filter cloth 5 is attached to each filter cloth mounting hole 4 so as to communicate with the opening 6 at the upper end of the filter cloth 5 serving as a dust collecting element formed into an elongated bag shape as a cylindrical shape. A cylindrical retainer 7 serving as a phasic structure for maintaining the shape is inserted and arranged from above, and a hopper 10 is connected to the lower end of the casing 2 so as to be connected to a lower end discharge portion of the hopper 10. A screw conveyor 9 is provided to discharge the collected dust 8.
A gas supply line 12 for introducing combustion exhaust gas 11 from an incinerator (not shown) is provided on a side portion of the hopper 10.
On the other hand, a gas discharge line 14 having an induction blower 13 is connected to the upper part of the casing 2, and the induction blower 13 is operated to induce the air.
The flue gas 11 guided into the casing 2 through the gas supply line 12 is passed from the outside to the inside of each filter cloth 5, and at this time, the dust 8 contained in the flue gas 11 is The combustion exhaust gas after collecting the dust 8 is guided as a clean gas 11a from the inside of the filter cloth 5 through the opening 6 to the upper side of the cell plate 3 and collected through the gas discharge line 14 downstream. Is discharged to a chimney (not shown).

By the way, in the bag filter 1, when the layer of the collected dust 8 attached to the outer surface of each filter cloth 5 becomes thicker as the dust collection processing of the combustion exhaust gas 11 is continued, the filter cloth 5 is removed. Since the differential pressure value between the inside and outside of the filter cloth 5 required for passing the filter cloth 5 increases and the processing capacity of the flue gas 11 decreases, the positive and negative of the differential pressure between the inside and outside of each filter cloth 5 is periodically or every time a required period elapses. Is reversed to perform backwashing, and dust 8 attached to the outer surface of each filter cloth 5 needs to be removed.

[0005] As one of the means for backwashing the filter cloth 5, as shown in FIG. 5, an example is shown in FIGS. 4 (a), (b) and (c). An outlet damper 15 for communicating and closing the gas discharge line 14 at a position above the cell plate 3 in the casing 2 in the filter 1 and a high-pressure backwash gas 16 connected to the upper portion of the casing 1 for guiding the gas discharge line 14. A backwash line 17 and a backwash damper 18 for communicating the backwash line 17 with the inside of the casing 2 and performing a closing operation are provided, as shown by a two-dot chain line in FIG.
After the outlet damper 15 is closed, the backwash damper 18 is opened, and the high-pressure backwash gas 16 introduced into the casing 2 through the backwash line 17 is caused to flow back from the inside of each filter cloth 5 to the outside. There is a backwashing apparatus of a type in which each filter cloth 5 is backwashed and a layer of dust 8 adhered to the outer surface is wiped off.

As another means for back-washing the filter cloth 5, one example of which is shown in FIG.
(B) As shown in (c), in the bag filter 1 at a position above the cell plate 3 in the casing 2 along one lateral wall of the casing 2 and along each array of the filter cloth mounting holes 4 in the lateral direction. A large number of air blow pipes 19 are arranged, and each air blow pipe 19 is provided with an air nozzle 20 facing each filter cloth mounting hole 4, that is, an opening 6 of each filter cloth 5. An opening / closing solenoid valve 21 is provided, and the high-pressure backwash gas 16 guided from the backwash gas supply unit (not shown) through the air blow tube 19 is supplied to the air blow tube 1.
9, the pressure in each filter cloth 5 is instantaneously increased by operating the electromagnetic valve 21 in the form of pulses in a pulsed manner from the air nozzle 20 so that the upper end of each filter cloth 5 A local deformation 22 swelling radially outward as shown by a dashed line is generated, and the local deformation 22 is moved downward to deform to a lower end portion as shown by a dashed line in FIG. Due to the deformation of the cloth 5, the filter cloth 5
There is a backwashing system of a type in which a layer of dust 8 adhered to the surface is washed off. Reference numeral 23 denotes a guide member provided above the filter cloth mounting holes 4 to efficiently guide the backwash gas 16 ejected from each air nozzle 20 to the opening 6 of each filter cloth 5.

[0007]

However, in the case of a backwashing apparatus of the type shown in FIG. 5 in which the backwash gas 16 is backflowed to backwash the filter cloth 5, the outlet damper 15 is used during the backwashing operation.
, There is a problem that the dust collection processing of the combustion exhaust gas 11 must be temporarily stopped, and a large amount of the backwash gas 16 to be fed into the bag filter 1 at the time of the backwash operation is required. When the dust collection process is restarted, the draft of the backwash gas 16 required for the above-mentioned backwashing operation must be performed together with the flue gas 11 to be processed normally, so the capacity of the draft blower 13 must be large. In addition, there is a problem that the temperature inside the bag filter 1 must be controlled at the temperature of the backwash gas 16.

On the other hand, as shown in FIG.
Backwashing system in which pressure is sprayed from an air nozzle 20 disposed above the opening 6 of the filter cloth 5, the backwash gas 16 is sequentially supplied to each air blow pipe 19. Thus, it is possible to backwash the filter cloths 5 arranged in the direction along each air blow pipe 19 one by one while continuously performing the dust collection processing of the combustion exhaust gas 11 by the bag filter 1. When the amount of combustion exhaust gas 11 to be increased or the amount of dust 8 adhering to the filter cloth 5 increases, the amount of air blown by the air blower 13 increases, and each filter cloth 5
Because the inside (downstream side) pressure of the air is greatly reduced as compared with the outside (upstream side), even if the backwash gas 16 is pressure-injected from the air nozzle 20, it is greatly drawn by the induction blower 13. As a result, there is a problem that the pressure difference between the inside and outside of the filter cloth 5 may not be reversed.

Therefore, the present invention provides a method for collecting a small amount of backwash gas without the need to temporarily stop the dust collection process and regardless of the total amount of gas to be collected and the amount of dust adhering to the dust collection element. It is an object of the present invention to provide a method and an apparatus for backwashing a filter-type dust collector, which can reliably reverse a differential pressure between an upstream side and a downstream side of a dust element to remove dust.

[0010]

According to the present invention, in order to solve the above problems, a cell plate having a large number of dust collecting element mounting holes is mounted at an upper position in a casing, and each cell plate of the cell plate is collected. An opening at the upper end of the bag-shaped or box-shaped dust-collecting element is attached to the dust-element mounting hole, and gas introduced from the lower part of the casing is discharged from the upper part of the casing by passing each dust-collecting element from outside to inside. In the backwashing method of performing backwashing of each of the dust collecting elements of the filtration type dust collector in which dust adheres to the outside of the dust collecting element and collects the dust, an upper end opening of the dust collecting element is provided. After individually closing the sections with the backwashing gas injection header, backwashing is performed by pressure-injecting the backwashing gas into each of the dust collecting elements through the backwashing gas injection header. Backwashing method and apparatus for filtering dust collector That.

When performing backwashing of the filter-type dust collector, an opening of one of the many dust collecting elements is closed by a backwash gas jet header, and then the backwash gas jet is used. When backwash gas is pressure injected from the air nozzle provided in the header,
Regardless of the amount of air blown by the air blower, the pressure inside the dust collecting element is reliably increased by the backwash gas, and the differential pressure between the inside and outside of the dust collecting element is reliably reversed, and the backwashing is performed. Will be performed. Such backwashing is sequentially performed for each dust collecting element, and backwashing is performed throughout the filter-type dust collector.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B show an embodiment of a method and an apparatus for backwashing a filter-type dust collector according to the present invention, and are shown in FIGS. 4A, 4B and 4C. Each of the cell plates 3 of the bag filter 1 in which a large number of filter cloths 5a, 5b, 5c, 5d, and 5e are disposed inside (in the figure, five pieces are shown in a row) as a similar configuration to the above. Above the filter cloth mounting hole 4, a large number (five in the figure) of backwash gas injection headers 2 whose lower ends can be fitted into the respective filter cloth mounting holes 4 are shown.
4a, 24b, 24c, 24d, and 24e are arranged so as to correspond to each other, and each of the backwash gas injection headers 24a,
Reference numerals 24b, 24c, 24d, and 24e denote fluid pressure cylinders 25a, 25b, and 25 as actuators, each of which is provided above the ceiling wall of the casing 2 so as to correspond to each other.
c, 25d, and 25e are connected to each other through piston rods 26 that penetrate the ceiling wall of the casing 2 slidably in the vertical direction.
5a, 25b, 25c, 25d, and 25e, each backwash gas injection header 2
4a, 24b, 24c, 24d, and 24e are lowered, and the respective backwash gas injection headers 24a, 24b, and 24 are lowered.
The peripheral edges of the bottom surfaces of c, 24d, and 24e are brought into close contact with the upper surfaces of the corresponding peripheral edges of the filter cloth mounting holes 4, so that the filter cloths 5a, 5b, 5c, and 5 attached to the filter cloth mounting holes 4 are formed.
The openings 6 of d and 5e can be closed.

Each of the backwash gas injection headers 24a,
As shown in FIG. 1 (b), each of the movable members 24b, 24c, 24d and 24e has a nozzle 27 for injecting the backwash gas 16 at the center of the lower surface, and can move up and down together with the piston rod 26. One end (lower end) of pipe 31
And the other end (upper end) of each of the movable pipes 31 is connected to a feeder 30 for the backwash gas 16.
Are connected to the header 32, and the injection solenoid valves 28a, 28b, 28c, 28d, 28e as opening / closing valves are provided on the way.
And is connected to a backwash line 29 having a swingable connection portion 33a through a swingable connection portion 33b, and the above-mentioned injection solenoid valves 28a, 28b, 28c,
By the operations of 28d and 28e, the backwash gas 16 is passed through the backwash line 29 and the backwash gas jet headers 24a, 24b,
24c, 24d and 24e, and further into filter cloths 5a and 5e.
b, 5c, 5d, and 5e.

Further, each of the hydraulic cylinders 25a, 25
The fluid pressure cylinders 25a, 25b, 25c, 25d, and 25 are provided in pressure passages 36 connected to the head-side pressure chambers 34 and the rod-side pressure chambers 35 of b, 25c, 25d, and 25e.
Lifting / lowering switching solenoid valves 38a, 38 as switching devices for individually switching the flow of the working fluid 37 to the pressure chambers 34, 35 on the head side and rod side for each e.
b, 38c, 38d, and 38e are provided, and the elevation switching electromagnetic valves 38a, 38b, 38c, 38d, and 38e and the corresponding injection electromagnetic valves 28a, 28b, and 28e are provided.
A control device 39 is provided for operating the devices c, 28d, and 28e in cooperation with each other.

Reference numeral 40 denotes a pump for supplying the working fluid 37 in the tank 41 to the pressure flow path 36. In addition, FIG.
The same components as those shown in (a), (b) and (c) are denoted by the same reference numerals.

The procedure for backwashing the bag filter 1 will be specifically described.

First, as shown in FIG. 1A, one of the up / down switching electromagnetic valves 38a, 38b, 38c, 38d and 38e, for example, the up / down switching electromagnetic valve 38a, is sent from the control device 39 to the lowering command 42. To perform a switching operation, and to transfer the working fluid 37 to the head-side pressure chamber 3 of the hydraulic cylinder 25a.
4 to extend the fluid pressure cylinder 25a, thereby lowering the backwash gas jet header 24a attached to the piston rod 26 of the fluid pressure cylinder 25a, and removing the backwash gas jet header 24a. Is brought into close contact with the opening 6 of the corresponding filter cloth 5a, and the opening 6 of the filter cloth 5a is
Is closed.

Next, an opening command 43 is sent from the control device 39 to the injection solenoid valve 28a corresponding to the backwash gas injection header 24a to open the injection solenoid valve 28a in a short time.
The backwash gas 16 from the feeder 30 is guided from the backwash line 29 to the backwash gas jet header 24a, and is jetted from the air nozzle 27 into the filter cloth 5a in a short time.

At this time, since the opening 6 of the filter cloth 5a is closed by the backwashing gas jet header 24a, regardless of the amount of air blown by the air blower 13, the backwash gas 1 is not affected.
The inner pressure is increased by the pressure injection of the filter cloth 5 and the filter cloth 5
The pressure difference between the inside and outside of the filter cloth 5a is reversed.
As shown by a two-dot chain line in (a), a local deformation 22 bulging in the radial direction at the upper end is generated, and the local deformation 22 is sequentially reduced from top to bottom as shown by a one-dot chain line in FIG. The deformation 22 causes the filter cloth 5a
The dust 8 adhered to the outer side surface of the device is removed.

Next, as shown in FIG. 2, after the injection solenoid valve 28a is closed by a close command from the control device 39,
The control device 39 sends an ascending command 44 to the ascending / descending switching electromagnetic valve 38a to be switched, and guides the working fluid 37 to the rod side pressure chamber 35 of the fluid pressure cylinder 25a to perform the contraction operation of the fluid pressure cylinder 25a. At the same time, the backwash gas injection header 24a is raised.

Thereafter, similarly to the control of the elevation switching electromagnetic valve 38a and the injection electromagnetic valve 28a by the control device 39, the lowering command 42, the opening command 43, and the elevation command 44 are transmitted from the controller 39 to the elevation switching electromagnetic valve. 38b and injection solenoid valve 2
8b, the dust 8 adhering to the outer surface of the filter cloth 5b is wiped off, and thereafter, the solenoid valves 38c, 38d, 38e for switching up and down and the solenoid valves 28c, 2c for injection are moved in the same manner.
By operating 8d and 28e, the dust 8 is removed from the filter cloths 5c, 5d and 5e in order.

Thus, the filter cloths 5a, 5b, 5c, 5
After the openings 6 of d and 5e are closed one by one, the backwash gas 16 is directly injected into the inside thereof.
1 and the amount of dust 8 adhering to each of the filter cloths 5a, 5b, 5c, 5d, 5e, a small amount of backwash gas 16 allows the inside and outside of each of the filter cloths 5a, 5b, 5c, 5d, 5e. The differential pressure can be reliably reversed, and each filter cloth 5a, 5b, 5
Since c, 5d, and 5e are backwashed one by one in order, dust collection can be performed on other filter cloths that have not been backwashed, and the dust collection of the combustion exhaust gas 11 can be continuously performed. Backwash gas 1 injected at a time.
Since the amount of 6 can be reduced, it is not necessary to increase the capacity of the induction blower 13.

Note that the present invention is not limited to the above-described embodiment, and the backwash line 29 is provided with injection solenoid valves 28a, 28b, 28c, 28d, 2 as shown in FIG.
8e, a fixed portion 45 penetrating through the casing 2 and extending to the inside of the casing 2. Further, instead of the movable pipe 31, the tip of each fixed portion 45 and the backwash gas jet headers 28a, 28b are provided. , 28c, 28d, and 28e, and the order in which the filter cloths 5a, 5b, 5c, 5d, and 5e are backwashed may be determined arbitrarily. As the actuator, the fluid pressure cylinders 25a, 25b, 25c, 2
Although 5d and 25e are shown, an actuator such as an electric jack which is electrically controlled by the control device 39 may be used, and the filter elements 5a, 5b, 5c and 5d each having a cylindrical bag shape as the dust collecting element. , 5e are shown, but the shape may be a box shape, or a porous material other than the filter cloths 5a, 5b, 5c, 5d, 5e may be used. May be freely determined as a large number. Further, when the number of dust collecting elements is large, the amount of the backwash gas 16 injected at a time does not significantly affect the capacity of the induced blower. Backwashing may be performed for each required number of units, or may be applied to a filter-type dust collector other than the bag filter 1 used to remove dust 8 such as fly ash from the combustion exhaust gas 11. Without departing from the gist of the present invention. It is needless to say that various changes and modifications may be made within the scope.

[0025]

As described above, according to the method and apparatus for backwashing a filter-type dust collector of the present invention, a cell plate having a large number of dust-collecting element mounting holes is mounted at an upper position in a casing. An opening at the upper end of a bag-shaped or box-shaped dust collecting element is attached to each dust collecting element mounting hole of the cell plate, and gas introduced from the lower portion of the casing is passed through each dust collecting element from outside to inside. In the backwashing method for backwashing each of the dust collecting elements of the filtration type dust collector, which is to be discharged from the upper part of the casing and during which the dust is attached to and collected on the outside of the dust collecting element, After individually closing the upper end openings of the dust collecting elements with the backwashing gas injection header, the backwashing gas is pressure-injected into the respective dust collecting elements through the backwashing gas injection header, and the backwashing is performed. Backwashing of filtration type dust collector characterized by performing washing Because it is a method and a device, regardless of the amount of gas to be collected and the amount of dust adhering to the dust collection element, a small amount of backwash gas must be used to reliably reverse the differential pressure inside and outside each dust collection element. The dust attached to the outer surface of each dust collecting element can be reliably removed, and the required number of dust collecting elements are back-washed in small increments. It is necessary to increase the capacity of the induction blower because the dust collection process can be continuously performed by other dust collection elements that are not performed, and the amount of the backwash gas that is pressure-injected at one time can be reduced. It has excellent effects such as no.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a method and an apparatus for backwashing a filter-type dust collector according to the present invention, in which (a) is a schematic sectional side view,
(B) is an enlarged side view of a cut of the backwash gas injection header.

FIG. 2 shows a state of the apparatus shown in FIG. 1 during a backwashing operation.
It is a cutting | disconnection side view which shows the state at the time of issuing a raising command by a control apparatus.

FIG. 3 is a schematic sectional side view showing another embodiment of the present invention.

FIG. 4 schematically shows an example of a bag filter.
(A) is a partially cut side view, (B) is a partially cut plan view,
(C) is an enlarged view of the part A of (a).

FIG. 5 is a cut-away side view schematically showing an example of a conventional bag filter backwashing device.

FIG. 6 is an enlarged side view schematically showing another example of a conventional bag filter backwashing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Bag filter 2 Casing 3 Cell plate 4 Filter cloth mounting hole (dust collecting element mounting hole) 5, 5a, 5b, 5c, 5d, 5e Filter cloth (dust collecting element) 6 Opening 8 Dust 11 Combustion exhaust gas 12 Gas supply line 13 Induction blower 14 Gas discharge line 16 Backwash gas 24a, 24b, 24c, 24d, 24e Backwash gas injection header 25a, 25b, 25c, 25d, 25e Fluid pressure cylinder (actuator) 26 Piston rod 27 Air nozzle 28a, 28b, 28c, 28d, 28e Injection solenoid valve (opening / closing valve) 29 Backwash line 38a, 38b, 38c, 38d, 38e Up / down switching solenoid valve (switching device) 39 Controller

Claims (2)

[Claims] 1. A cell plate having a large number of dust collecting element mounting holes is attached to an upper position in a casing, and a bag-shaped or box-shaped dust collecting element is inserted into each of the cell collecting plate mounting holes. The dust introduced from the lower part of the casing is passed through the respective dust collecting elements from the outside to the inner side and discharged from the upper part of the casing, and during this time, the dust adheres to the outside of the dust collecting element and is captured. In the backwashing method of performing backwashing of each of the dust collecting elements of the filtration type dust collector that is configured to collect, after individually closing an upper end opening of the dust collecting element with a backwashing gas injection header. Backwashing of the filter-type dust collector, wherein backwashing is performed by injecting backwash gas into each of the dust collecting elements under pressure through the backwash gas jet header. 2. A cell plate having a number of holes for mounting dust collecting elements is mounted at an upper position in a casing having a gas supply line connected to a lower part and a gas discharge line connected to an upper part. The opening at the upper end of the bag-shaped or box-shaped dust collecting element is attached to the dust collecting element mounting hole, and the gas to be subjected to the dust collecting process introduced from the gas supply line at the lower part of the casing is moved from the outside to the inside of each of the dust collecting elements. Through the gas exhaust line at the upper part of the casing, during which the dust in the gas adheres to the outside of the dust collecting element and is collected and collected at a position above the cell plate in the filter type dust collector, A large number of backwashing devices having nozzles for pressure-injecting gas in the backwash into the respective dust collecting elements on the lower surface so as to close the openings by closely contacting the openings of the respective dust collecting elements from above. A gas injection header is arranged, and each of the backwashing gas injection headers is connected to an elevating actuator provided at an upper portion of the casing so as to be individually raised and lowered. A backwash line connected to the header, a switching device for raising and lowering each of the actuators, an opening and closing valve for opening and closing each of the backwash lines, a switching command for giving a switching command to each of the switching devices, and the opening and closing valve; A backwashing device for a filter-type dust collector, comprising: a control device for giving an opening / closing command to a filter.