JPH05168833A - Method for washing bag filter - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to maintain the dust removal efficiency of each bag filter constant. [Structure] A dust collection cell 1 is divided into two upper and lower chambers 1a and 1b by a bag filter 4. A differential pressure gauge 21 for measuring a differential pressure between the upper and lower two chambers 1a and 1b is set for each cell 1 unit, and each differential pressure gauge 21 is connected to a controller 30. An injection pipe 5 is provided above the bag filter 4. The inlets of the injection pipes 5 of the respective dust collecting cells 1 are communicated with each other through the injection pipe electromagnetic valve 6 by the compressed air common pipe 7, and the compressed air common pipe 7 is communicated with the blower 9 through the compressed air supply pipe 8. There is. Each solenoid valve 6 is connected to the controller 30 and is opened and closed in a predetermined cycle according to a command from the controller 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a bag filter, which removes dust in a gas being sent by colliding a high-pressure air pulse with a predetermined pitch to remove the attached dust.

[0002]

2. Description of the Related Art A conventional dust filter including a bag filter and a filter cleaning device for removing dust adhering to a filter cloth of the bag filter is, for example, Japanese Patent Publication No. 58-24.
There is one described in Japanese Patent No. 168. In this, the dust-containing gas sent to each cell is sent while being filtered from the lower side of the bag filter toward the upper side thereof to remove dust. The bag filter uses a horizontal tube plate to separate the inside of the cell into upper and lower chambers, and a sleeve-shaped filter cloth that removes dust in the gas is installed in a plurality of concentric openings in the tube plate. Is configured.

Above the tube plate, an injection tube of a filter cleaning device of the pulse jet type or the like is arranged.
The injection pipe has a plurality of nozzles that can face up and down with a plurality of openings formed in the tube plate, and is extended in the radial direction of the concentric circle, while rotating around the center of the concentric circle, A high-pressure air pulse is ejected from the nozzle at a predetermined pitch, the air pulse is made to collide with the filter cloth facing at that time, and the dust adhering to the filter cloth is wiped off by the vibration, The pressure loss of the bag filter is kept below the set value.

Since the bag filter has a slower filtration speed than other filtration systems, it is necessary to increase the filtration area of the bag filter formed by the filter cloth in order to filter blast furnace gas and the like. In view of the maintenance efficiency of the filter cloth, the bag filter is usually divided into a plurality of cells and arranged. Therefore, the dust-containing gas is conveyed from the upstream plant such as the blast furnace by the dust-containing duct, and the dust-containing gas is distributed to each cell through the plurality of auxiliary ducts communicating with the dust-containing gas duct.

[0005]

Comparing the cell that takes in the dust-containing gas on the upstream side of the dust-containing gas duct with the cell that takes in the dust-containing gas on the downstream side of the dust-containing gas duct, the former cell Since the particle size of the dust in the gas taken in the latter cell is often smaller than that in the latter case, the amount of dust adhering to the bag filter mounted in the latter cell is usually large.

As described above, the particle size distribution and the content rate of dust in the gas taken in each cell are not necessarily the same. However, in the above-mentioned conventional filter cleaning device, since air pulses are jetted to all cells at the same pitch for cleaning, a difference occurs in the degree of clogging in each cell, resulting in dust removal in each bag filter. There is a problem in that it is difficult to maintain the dust collection efficiency of the dust collection device at a constant level due to variations in performance.

For example, when an air pulse is injected into each bag filter at the same pitch, the bag filter of the cell that takes in gas from the downstream side of the dust-containing gas duct will have a bag bug of the cell that takes in gas from the upstream side. Compared with a filter, it is more likely to be clogged, and thus pressure loss is likely to increase. The present invention has been made in view of the above problems, and an object thereof is to maintain a constant dust removal efficiency by a bag filter.

[0008]

In order to achieve the above object, a method of cleaning a bag filter according to the present invention relates to a dry dust collector having a plurality of cells and a bag filter provided for each cell. Then, in the bag filter cleaning method of injecting air pulses into the bag filter of each cell at a predetermined pitch to clean the bag filter of each cell, each air pulse to the bag filter whose pressure loss is larger than the target value. The injection pitch of each air pulse to the bag filter whose pressure loss is smaller than the target value and the pressure loss is smaller than the target value. It is characterized by lengthening accordingly.

[0009]

As described in the section "Problems to be solved by the invention", the bag filters mounted on each cell constituting the dry dust collector are cleaned by using air pulses at the same pitch. However, the amount of dust adhering to each bag filter is different, and the pressure loss of each bag filter is different.

As a result, the dust removal capability of the bag filter having a large pressure loss is reduced, and the dust collection efficiency of the dust collector as a whole is slightly reduced. In the present invention, the pressure loss is constantly detected from the pressure difference between the inlet side and the outlet side of the bag filter of each cell, and it is checked whether or not it is equal to or higher than a target value, and the cell in which the current pressure loss is larger than the target value. , The air pulse injection pitch for the cell is shortened according to the increment of the current value with respect to the target value.

If the current value is smaller than the target value, the number of cleanings per unit is too large, so the injection pitch is lengthened according to the increment of the current value with respect to the target value. The change of the pitch may be performed in a predetermined time unit. As a result, the pressure loss of all bag filters approaches the target value, the dust removal efficiency of each bag filter becomes constant, and the dust collection efficiency of the dust collector is maintained constant.

[0012]

Embodiments of the present invention will be described with reference to the drawings.
First, the structure will be described. As shown in FIG. 2, the dry dust collector has eight dust collecting cells 1, and the eight dust collecting cells 1 correspond to two filter cleaning devices. It is divided into two sets of dust collecting blocks 2 arranged in a line with four groups each.

The two sets of dust collecting blocks 2 are arranged in parallel in two rows, and a duct 3 is arranged between the two dust collecting blocks 2, and the duct 3 feeds from a blast furnace or the like (not shown). The collected dust-containing gas is distributed to each dust collecting cell 1,
In addition, the gas dedusted by each dust collecting cell 1 is discharged. The dust collecting cell 1 includes a bag filter 4 as shown in FIG.
Is divided into two upper and lower chambers 1a and 1b, the upper chamber forming a dust-free gas chamber 1a and the lower chamber forming a dust-containing gas chamber 1b.
The lower side of the dust-containing gas chamber 1b serves as a hopper to form a dust collecting chamber 1c for accumulating dust removed from the dust-containing gas. A differential pressure gauge 21 for measuring a differential pressure between the upper and lower two chambers 1a and 1b is set for each cell 1 unit, and each differential pressure gauge 21 is connected to a controller 30 so that the inlet side of each bag filter 4 can be connected to the controller 30. The differential pressure between the output side and the output side is supplied.

The dust accumulated in the dust collecting chamber 1c is discharged from the dust collecting cell 1 by opening the rotary valve 31 at a predetermined timing. The bag filter 4 is
It is composed of a tube plate 4a and a plurality of filter cloths.
As shown in FIG. 4, a plurality of filter holes 4b are concentrically formed, and a sleeve-shaped or envelope-shaped filter cloth fixed to each filter hole 4b is arranged in the dust-containing gas chamber 1b. ..

An injection pipe 5 is provided above the bag filter 4. The injection pipe 5 is extended in the radial direction of the tube plate 4a, a plurality of nozzles are provided on the lower surface of the tube plate 4a at predetermined intervals, and the tip end of the nozzle is the filter hole 4 of the tube plate 4a.
It can be opposed to b at a predetermined interval. The injection pipe 5 is provided with a drive device composed of a motor and a speed reducer at the upper part, and is rotated along the upper surface of the tube sheet at a predetermined speed around the center of the tube sheet by the drive device. ..

The dust collecting blocks 2 arranged in a line
Each of the four injection tubes 5 installed in each of the four dust collecting cells 1 constituting the
Of each of the dust collecting blocks 2 are communicated with each other through a separate injection pipe solenoid valve 6 by a compressed air common pipe 7, and the compressed air common pipe 7 is connected to one end of a compressed air supply pipe 8 on the dustless gas discharge side. The other end of each compressed air supply pipe 8 communicates with each blower 9 that supplies high-pressure air.

Further, as shown in FIG. 5, the duct 3 is vertically divided by a partition plate 12 which is inclined from the upper portion of the gas inlet 10 toward the lower portion of the gas outlet 11. The lower side forms the dust-containing gas duct 13 and the upper side forms the dust-free gas duct 14. Dust-containing gas duct 1
An auxiliary duct 15 is provided on the lower surface of 3 to communicate with the dust collecting chamber 1c of each dust collecting cell 1 from the side, and the dust-containing gas is contained in each dust collecting cell 1 via the auxiliary duct 15. Dust gas chamber 1
can be supplied to a.

The dust-free gas duct 14 is a horizontal flat plate 1.
Gas is allowed to flow through a gas communication port 16 a provided in the flat plate 16 and divided into upper and lower parts by 6.
The upper chamber is also partitioned at the boundary of the dust collection cell 1, and the partitioned chamber is also partitioned into two by the baffle plate 17 to be partitioned into a total of eight chambers.
In each of the partitioned chambers, a hole 18 which is a communication passage provided in one-to-one correspondence with the dust-free gas chamber 1b of the dust collection block 1 is provided in the side wall portion of the dust-free gas chamber 1b.

A disc 19 having a diameter larger than that of the communication port 16a is opposed above the gas communication port 16a provided in the flat plate 16, and the disc 19 is connected on the upper side. The cylinder device 20 can move up and down, and the communication port 16a can be closed. As shown in FIG. 1, each solenoid valve 6 is connected to a controller 30 and is opened and closed in a predetermined cycle according to a command from the controller 30. Then, in a normal time, the controller 30 controls each of the injection pipe solenoid valves 6 to be in an open state periodically, for example, at a cycle of 2 or 3 times per minute, and at the same time, controls each cell in a predetermined time unit. The differential pressure of each cell is checked from the differential pressure gauge to check if there is any fluctuation from the target value. It should be noted that the target value has a predetermined width above and below.

In the apparatus as described above, the dust-containing gas sent from the blast furnace or the like is taken into the dust-containing gas duct 13 from the gas suction port 10 of the duct 3, and then the dust-containing gas duct 13 is fed to the auxiliary duct 15. The dust-containing gas chamber 1a of each dust-collecting cell 1 is passed through, and dust in the gas is further removed by a filter cloth and sent to the dust-free gas chamber 1b. The dust-free gas is sent to the upper chamber 22 of the dust-free gas duct 1b through the hole 18 formed in the wall portion, and further, the dust-free gas duct is passed through the gas communication port 16a provided in the flat plate 10. 14 is sent to the lower chamber and is discharged from the gas discharge port 11.

At this time, high pressure air is sent to each dust collecting block 2 from each blower 9 via the compressed air supply pipe 8 to the compressed air common pipe 7, that is, the inlet of the injection pipe 6 of each block 2. At this time, the injection pipe solenoid valve 6 controlled by the controller 30 is opened for a predetermined time at a predetermined time unit, for example, twice per minute, and the solenoid valve 6 is opened for high pressure air. It is sent into the injection pipe 5 and jetted downward through the nozzle. The jetted high-pressure air collides with the filter cloth through the filter holes 4b of the tube sheet 4a facing each other at that time, and instantaneously vibrates the filter cloth to remove dust adhering to the filter cloth. It is deposited in the lower dust collecting chamber 1c.

At this time, for example, assuming that the injection pitches of the high-pressure air from the respective injection pipes 6 are all set to the same pitch, the ducts on the downstream side of the dust-containing gas chamber 1a of the cell 1 on the upstream side of the duct 3 are arranged. Since the particle size of the dust in the gas taken into the dust-containing gas chamber 1a of the cell 1 is small, the bag filter 4 in the cell 1 on the downstream side is more likely to deposit dust, and the bag filter 4 on the downstream side is more likely to adhere. The pressure loss of becomes larger than the target value.

In this embodiment, when the pressure loss of the bag filter becomes large as described above, the controller 30 inputs it from the differential pressure gauge 21 which measures the differential pressure between the inlet side and the outlet side of the bag filter 4. By recognizing that the pressure loss has increased from the value variation, the opening / closing pitch of the corresponding solenoid valve 6 is made faster than the set value by the amount corresponding to the increment. As a result, the cleaning of the bag filter 4 of the cell 1 on the downstream side per unit time is increased, the clogging of the bag filter 4 is reduced, the pressure loss is reduced, and the dust removal processing capacity of the bag filter 4 is the target value. Will be returned to.

If there is a bag filter 4 whose pressure loss is smaller than the set value, the controller 3
0 recognizes it by the input value from the differential pressure gauge 21 and lengthens the injection pitch to the air pulse from the injection pipe 6 in accordance with the increment of the pressure loss with respect to the set value, so that the unit per unit for the bag filter is increased. Reduce the number of washes. As a result, only the pressure loss of the specific bag filter 4 increases and the dust removal capability of the bag filter 4 decreases, or only the pressure loss of the specific bag filter 4 decreases and the gas suction degree of the bag filter 4 increases. As a result, the gas intake of each cell becomes stable, and the dust removal efficiency of each bag filter 4 is fed back to a predetermined value.
The dust collecting efficiency in the dust collecting device provided with the plurality of bag filters 4 is maintained constant.

Although the injection pitch is changed for each bag filter 4 in the above embodiment, the particle size of dust in the taken-in gas is coarse and the particle size of dust in the gas is fine. It is also possible to perform grouping on the two downstream side units or the like, or to group the jet pipes 5 facing each other on the left and right sides of the two pairs of filter cleaning devices so that the jetting pitch is changed for each group. Absent.

[0026]

As described above, in the bag filter cleaning method of the present invention, since the dust removal processing capacity of each cell is always kept constant, the dust collection efficiency of the dry dust collector is kept constant. The effect is that it can be maintained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a dry dust collecting apparatus and a filter cleaning apparatus therefor according to an embodiment of the present invention.

FIG. 2 is a top view of a dry dust collector according to an embodiment of the present invention.

FIG. 3 is a view showing a tube sheet according to an embodiment of the present invention.

FIG. 4 is a side sectional view showing a duct of a dry dust collector according to an embodiment of the present invention.

[Explanation of symbols]

 1 Dust collection cell 1a Dust-free gas chamber 1b Dust-containing gas chamber 2 Dust collection block 4 Bag filter 5 Injection pipe 6 Injection pipe solenoid valve 7 Common compressed air pipe 8 Compressed air supply pipe 9 Blower 21 Differential pressure gauge 30 Controller

Claims (1)

[Claims] 1. A dry-type dust collector having a plurality of cells and a bag filter provided for each cell, wherein air pulses are jetted at a predetermined pitch to each bag filter to remove dust adhering to the bag filter. In the cleaning method of the bag filter to be blown off, the injection pitch of the air pulse to the bag filter whose pressure loss is larger than the target value is shortened according to the increment of the pressure loss target value, and the pressure loss is the target value. A method for cleaning a bag filter, wherein the injection pitch of the air pulse for the bag filter which is smaller than the above is lengthened according to the increment of the pressure loss with respect to the target value.