JPH067892B2 - Backwashing method for dry dust collector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a backwashing method for a dry dust collecting apparatus that employs backwashing backwashing means.

[Conventional technology]

Since the bag filter of the dry dust collector causes clogging due to fine dust in the dust-containing gas generated in the blast furnace casting floor, etc., it causes various problems. Backwashing for removing the dust accumulated on the filter cloth in the filter chamber (element) is performed at appropriate times by the washing means. Conventionally, such backwash is disclosed in, for example, Japanese Patent Laid-Open No. 57-207522.
A clean gas filtered by another element is blown into one element of a plurality of elements of the dust collector from a clean gas exhaust port of the element for several tens of seconds, and by this back pressure, a cylindrical bag filter cloth Is a method of squeezing dust into a star-shaped cross section and discharging the accumulated dust to the dust-containing gas side (dust chamber) in the element.

As shown in FIG. 5, the back pressure is generated by elements 3 ₁ , 3 ₂ , ..., 3 in which the bag filter 15 is built in, as shown in FIG.
_In a dry dust collector consisting of ₁₀ , for example, element 3
₁₀ Dust-containing gas inlet damper 2 ₁₀ is closed and back pressure damper 5 ₁₀
Is opened to suck outside air or clean gas from the air intake port (or clean gas exhaust port) 4 ₁₀ by the suction force of the blower 1 to backwash the bag filter 15. Reference numeral 6 denotes a backwash duct for sending the gas containing backwashed dust to the blower 1, and 14 denotes a damper for adjusting the backwash pressure. After the backwashing of the element 3 ₁₀ is completed, the dust-containing gas inlet damper 2 ₁₀ is opened to bring it into a normal state, and the backwashing of the other elements is sequentially performed. Alternatively, as shown in FIG. 6 (a), if the clean gas outlet damper 12 ₁₀ of the element 3 ₁₀ is closed and the atmosphere suction damper 13 ₁₀ is opened, the suction force of the blower 1 causes the inside of the dust chamber 9 of the element 3 ₁₀ to become negative. The pressure is applied, and the dust accumulated on the filter cloth of the bag is blown off into the dust chamber 9 due to the invasion of the atmosphere. Further, the gas after the backwash is sent into the dust collecting main pipe 8 and mixed with the dust-containing gas (see FIG. 6 (b)). Then, this dust-containing gas passes through the adjacent element 3 as shown in FIG.
Is fed to the _{1-3 9} is filtered by the bag filter 15, the clean gas in the open outlet damper ₁₂ 1 to 12 ₉
The gas is introduced into the clean gas main pipe (not shown) or the atmosphere.

[Problems to be Solved by the Invention]

However, in any of the above cases, the dust adhering to the filter cloth is re-scattered and considerably contained in the reverse air flow after the bag filter 15 and the filter cloth are crushed. It will be treated together with the dust-laden gas in the element that has not been backwashed. As a result, the amount of dust that is re-scattered increases the dust load on each element that is not backwashed, and depending on the nature of the dust that is collected, the number of elements, and the interval of backwashing frequency, the dust collection main 8 In some cases, the amount of dust circulated due to re-scattering may be larger than the amount of dust carried by.

As described above, the back-pressure backwashing means has a drawback that a large amount of blower power is required as a result of an increase in pressure loss of the filter cloth of the bag filter 15 having an increased dust load. Also, the degree of this pressure loss increase is strongly influenced by the amount of re-scattered dust or the particle distribution. For example, in the case of a large dust collector with a processing capacity of 9000 ³ / min used in a blast furnace, this Of the total amount of dust entering the equipment, 50% was re-scattered during this backwash and the particle size was much smaller, so 90% of the total resistance generated in the dust layer accumulated on the filter cloth was due to the circulation of the backflow air. It was the result. Further, in the push-in type dust collector, since the impeller of the blower is subjected to accelerated wear due to this circulating dust,
It was also a problem in equipment maintenance.

The present invention has been made in view of such conventional problems, and by providing a small-capacity dust collector for collecting the re-scattered dust in the middle of the backwash duct, the above-mentioned problem is solved. The purpose is to solve the problem.

[Means for Solving the Problems]

In order to achieve the above object, the present invention, in bag filter backwashing of a dry dust collector that employs backwashing means of backpressure blow-off type, dust that re-scatters at the time of dusting off,
This is a method of collecting using a separately provided backwashing special dust collector.

[Action]

Since the present invention is configured as described above, the dust that is re-scattered as a result of backwashing is collected by a separately provided backwashing dust collector without directly mixing into the dust collecting main line as in the conventional case. As a result, since it does not affect the dust load of the other bag filters 15 that are not backwashed, a defect such as that caused by increasing the dust load in the related art is as follows.
I can prevent everything.

〔Example〕

Hereinafter, the present invention will be described with reference to the drawings. The same parts as those in the conventional example are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 shows the first embodiment, and in FIG. 1 (a), the blower 1 has an element 3 ₁ incorporating a bag filter,
It is provided upstream of the dust collector 3 composed of 3 ₂ , ..., 3 ₁₀ (this type is referred to as a push type). Each element has a dust-containing gas inlet damper 2, a back pressure damper 5, an atmosphere or a supply for communicating with the atmosphere or an atmosphere and a clean gas main pipe (not shown).
The exhaust port 4 is provided so that the backwashing operation can be performed for each element. FIG (a) is an element 3 ₁₀ that is performing backwash, Fig (b) is ₁ element 3 doing ordinary dust containing gas _filtration, 3 _2, ..., shows the 3 ₉ details.

Now, in the element 3 ₁₀ being backwashed, the dust-containing gas inlet damper 2 ₁₀ is closed, the backpressure damper 5 ₁₀ is opened, and the inside of the dust chamber 9 is made a negative pressure by using the inlet side negative pressure of the blower 1. There is.
Therefore, the atmosphere is sucked from the air supply / exhaust port 4, a back pressure is applied to the bag filter 15, and the accumulated dust is blown off into the dust chamber 9. Then, the dust re-scatters, and the air flow containing this dust flows from the open back pressure damper 5 toward the dust collecting main pipe 8 in the backwash duct 6.
On the way, the dust collector 7 for backwashing collects this dust. The dust collector 7 is selected so that it can continuously filter the gas containing relatively fine dust. The reverse airflow passes through the dust collector 7 and becomes clean air (or clean gas) and flows into the dust collecting main pipe 8. Therefore, with impeller wear of the blower 1 is reduced, since the amount of dust that is charged to the other elements 3 ₁ to 3 ₉ dust containing gas filtration is also reduced, the pressure loss of the blower 1 delivery side is reduced, blowing mobility Can be reduced.

FIG. 2 shows an embodiment in which a back pressure blower 11 is disposed downstream of the back wash dedicated dust collector 7 as a back wash negative pressure generation assisting means, and the negative pressure by the blower 1 is insufficient for back wash. If
Alternatively, it is convenient when the negative pressure becomes insufficient due to the pressure loss of the backwash pipe 6.

FIG. 3 is an example in which the above embodiment is further developed, and is an apparatus in FIG. 2, which depends on the blower 10 provided with a separate negative pressure for backwashing. In this method, not only the dust blown off by the element during a certain backwash but also the clean gas after the backwash can be treated outside the device independently, so even if the dust collection air volume is the same, the air volume after the inlet side of the blower 1 is the same. Is reduced by the amount of backwash air, the pressure loss of the blower 1 is smaller than that in the embodiment shown in FIGS. Moreover, in many cases, the rotation speed of the blower 1 is controlled in a large dust collector, but when the rotation speed is reduced, the negative pressure on the inlet side of the blower 1 is also reduced, and a sufficient brush-off effect cannot be obtained, which is temporary. Then, the filter cloth of the bag filter 15 will be clogged. On the other hand, in the present embodiment in which the blower 10 dedicated to backwashing is installed, the negative pressure for backwashing can be independently generated regardless of the operating state of the blower 1, so that a stable cleaning effect can be obtained. Is obtained, which is advantageous. Furthermore, by controlling the blower so that the negative pressure on the inlet side of the blower 11 is constant, it is possible to realize an ideal backwash operation without damaging the bag filter 15 due to excessive backpressure. is there.

The embodiment shown in FIG. 4 is a suction type of the above embodiment shown in FIG. 3, and since the filtered clean gas flows into the inlet side of the blower 1, the impeller wear of the blower 1 is reduced. It can be greatly reduced. Now element 3
_{In order to} backwash ₁₀ , clean gas outlet damper 12 ₁₀ is closed,
The dust-containing gas inlet damper 2 ₁₀ is closed, the backwash damper 5 ₁₀ and the atmospheric suction damper 13 ₁₀ are opened, and the dampers of the other elements are all opposite to the element 3 ₁₀ . Therefore, the dust collecting main 8
The dust-containing gas passing through the fan is sucked by the blower 1 and the element 3
_{1, 3} 2, ... enter the _{3 9,} the outlet damper 12 is filtered
_1, the ...... 12 ₉ into the atmosphere by the blower 1, or is guided into the clean gas mains. On the other hand, element 3 being backwashed
₁₀ enters from the supply and exhaust port 13 ₁₀ air or cleaning gas to the element 3 _10, the bag filter 15 and backwash, backwash air flow passes through backwash dedicated dust collector 7 from backwash damper 5 _10, cleaning It becomes an air flow (or clean gas) and is guided to the atmosphere or to the clean gas main by a blower capable of controlling the negative pressure on the inlet side in the same manner as above, and the impeller wear of the blower 1 is further from the above. Also has the advantage of becoming smaller.

In this embodiment, the dust collector element is
Although the number of elements is set, the number of elements is not limited in the present invention.

〔The invention's effect〕

As described above, the present invention has the following excellent effects.

(1) Since there is no dust that is recirculated when backwashing is performed, the pressure loss of the bag filter can be reduced accordingly, and the power of the blower can be greatly reduced.

(2) Even in the case of the push-in type dust collector, the amount of dust passing through the blower is significantly reduced, so that the wear of the blower impeller can be reduced.

Further, the suction dust collector can further reduce impeller wear.

(3) The collected dust is fine particles in the backwashing dust collector.
Coarse particles are formed on the bag filter side, and a classification action occurs, which is advantageous for dust recycling.

[Brief description of drawings]

Fig. 1 shows an embodiment of a push-in type dust collector, Fig. 1 (a) is an overall schematic diagram, Fig. 1 (b) is a detailed diagram of an element (bag filter) during backwashing, and Fig. 1 (c). Is a detailed view of emerent during filtration and dust collection, and FIG. 2 is a schematic view of a second embodiment in which a back pressure blower is attached to the embodiment shown in FIG. 1 to improve efficiency, and FIG.
FIG. 4 is a schematic diagram of a third embodiment in which the load of the blower is significantly reduced, FIG. 4 is a schematic diagram of a suction type embodiment in which the load of the blower is significantly reduced, and FIG. FIG. 6 shows a conventional suction-type example, FIG. 6 (a) is a schematic diagram thereof, and FIG.
Is a detailed drawing of the element (bag filter) being backwashed.
(c) is a detailed view of the element in the filter dust collection. A, B, C, D, E, F ... Dry dust collector, 15 ... Bag filter.

Claims (1)

[Claims] 1. When using a back-cleaning bag filter of a dry dust collector that employs a back-pressure-discharging type back-washing means, a back-washing dust collector is separately provided for dust that re-scatters when the dust is blown off. A method of backwashing a dry dust collector, which is characterized by collecting.