JPH01262915A - Method for precoating filter cloth and dust collecting apparatus - Google Patents

Abstract

PURPOSE:To save the troubles of purchasing, storing and feeding precoating agent as conventionally done and thus make an inexpensive precoating possible, by separating the ducts adhered to filter cloth for reuse as the precoating agent. CONSTITUTION:A dust-containing air being supplied is filtered through filter cloth and the adhered dusts are separated therefrom by a separating means such as reversely blasting air and vibrating. The dusts thus separated are recovered and such recovered specific part of dusts are partially recycled for attachment to the filter cloth as a precoating agent. This saves the troubles of purchasing, storing and feeding the precoating agent as conventionally done, making an inexpensive precoating possible. At the time of conventionally using the collected dusts for other purposes, the precoating agent remaining therein offers a problem as the foreign matter. By this method, however, the precoating agent is removed from the collected dusts for recycle and the dust free therefrom can be reused without presenting the aforesaid problem.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method and collection of precoating filter media for filtering dust, particularly fumes containing fixed substances generated by combustion and thermochemical reactions (one furnace, one for each furnace, one for melting, one for melting, and one for welding). ! between the devices. [Prior Art] In order to prevent the above-mentioned fumes from contaminating the environment, a method of filtering them using a filter cloth is generally adopted. However, hume has the disadvantage that it contains fixed substances and causes early clogging of the filter cloth (diagram A in FIG. 3). It is difficult to remove this by normal pressure air injection or vibration application, and therefore a pre-coat agent is usually attached to the filter cloth to facilitate removal. [Invention tries to solve it! ! [Problem] As the precoat agent, a method is generally adopted in which a commercially available one is purchased and used. However, this precoat agent must be supplied each time the filter cloth is cleaned by back spraying, etc., and there are problems such as the amount used is large, the cost is increased, and it requires time and effort for continuous parts and storage. Further, depending on the type of dust, it may be possible to use it for other purposes, but there are also problems such as the pre-coat agent being mixed in as a foreign substance, making it unsuitable for use. As a result of various experiments, the present invention has focused on the fact that the collected dust can be used as a precoat agent, and aims to solve the above-mentioned drawbacks by utilizing the collected dust.

[Means to solve problems]

In order to achieve the above object, in the filter cloth precoating method of the present invention, the supplied dust-containing air is filtered through the filter cloth, and the adhering dust is peeled off by a peeling means such as back injection with pressurized air or vibration application. The purpose is to collect the peeled dust and supply a part of the collected dust as a pre-coat agent to the filter cloth. Further, the dust collector for carrying out the above method includes a main body of a collector equipped with a filter cloth for filtering dust-containing air and a peeling means for peeling off dust adhering to the filter cloth, and The intermediate take-out part is connected to the dust-containing air intake side of the dust collector main body through a return duct, and the intermediate take-out part receives and stores a part of the dust. This is performed in conjunction with precoating by supplying stored dust. The dust collector main body is divided into a filtration chamber for introducing dust-containing air and a purification chamber for storing purified air formed on the side of the filtration chamber, and a filter cloth is provided in the filtration chamber as a bag filter.
In addition, it is preferable that the duct for returning the accumulated dust opens to the purification chamber side, opens to the upper part of the filtration chamber, and supplies the accumulated dust from above the filter cloth as a pre-coat agent. The main body of the dust collector is divided into multiple unit dust collection chambers, each of which is equipped with a filtration chamber for housing a bag filter, a purification chamber for storing purified air, and a means for peeling off the dust adhering to the bag filter, and is connected to a common conveyor for conveying the peeled dust. The conveyor is equipped with an intermediate take-out part that receives a portion of the transferred dust, and the intermediate take-out part is connected to the filtration chamber of each of the unit dust collection chambers via a switching valve, and each unit dust collection chamber is sequentially removed by a stripping means. It is also possible to perform cleaning of the filter cloth by using the filter cloth and pre-coating by supplying the dust stored in the intermediate take-out part. [Function] A part of the dust peeled off from the filter cloth is accumulated, returned to the filter chamber, and adhered to the filter cloth, so that it can act as a precoating agent. In this case, when the dust is supplied from above the filtration chamber, the dust can be uniformly and quickly adhered to the entire surface of the filter cloth. In addition, the dust collector body is divided into multiple unit dust collection chambers, and the filter cloth of each unit dust collection chamber is cleaned sequentially and pre-coated by supplying stored dust from a common intermediate extraction part, thereby improving the dust collection function. The impact can be reduced. [Embodiment] FIGS. 1 to 3 show a first embodiment. The dust collector f includes a dust collector main body 2 and a transfer conveyor 3 for transporting dust discharged from the main body. The dust collector main body 2 has an inner chamber divided by a vertical space U4, and one side is a filtration chamber 6 connected to a fume-containing air introduction duct 5.
and the other is designated as a purified air chamber 7. The duct 5 opens above the filtration chamber 6, and is of a so-called top inlet type, and a hopper 8 for collecting dust is formed in the lower part of the filtration chamber, and the hopper 8 is shaped sequentially toward the bottom, and a rotary valve 9 is attached to the lower part of the hopper. It is designed to keep the accumulated dust airtight while discharging it. A large number of bag filters 10 are arranged in parallel at predetermined intervals in the filtration chamber 6, and the frontage portions are attached to the partition wall 4, and the purified air chamber 7 is provided with a funnel-shaped venturi 11 connected to the opening of the bag filter 10. Installation and Venturi]
An injection pipe 12 for injecting high-pressure air is installed opposite to the injection pipe 1. That is, in this embodiment, the venturi 11 and the injection pipe 1 are used as the peeling means P for peeling off the dust adhering to the bag filter 10.
Although the reverse injection method according to No. 2 has been shown, this may also be, for example, a vibration imparting method. The transfer conveyor 3 is composed of, for example, a screw conveyor, and an intermediate take-out part 20 is provided at a suitable location on the conveyor to take out a part of the dust being sent out, and a discharge part 25 is provided at the end to discharge the remaining dust, each of which has a rotary valve. 21. Attach 26. The dust taken out from the intermediate take-out section 20 is used as a pre-coating agent for the bag filter IO, and the hopper 22 of the pre-coating agent supply device is connected, and the dust accumulated in the hopper is passed through the return duct 23 to the introduction duct 5. is supplied to 24 and 27 are on-off valves provided in the return duct 23 and the introduction duct 5, respectively. In the figure, 30 is a fume generator such as an electric furnace or other combustion furnace;
Reference numeral 31 is a foot provided opposite to this fume generator and connected to the introduction duct 5. In addition, 40a and 40b are the filtration chambers 6
Differential pressure between and purified air chamber 7 (filtration resistance of bag filter)
40a is a differential pressure detector that detects a set high differential pressure, and 40b is a differential pressure detector that detects a set low differential pressure and issues a signal. Further, 13 indicates an exhaust duct, and 14 indicates a suction blower. Next, the procedure for precoating the bag filter 10 will be explained. Figure 3 shows an example of pressure change over time in the bag filter 10, where the vertical axis shows pressure loss and the horizontal axis shows time. This shows the pressure change when the gas is supplied without any treatment. The fume contains fixed substances, so clogging is severe, and the pressure loss through the bag filter rapidly increases as shown in the figure. In this case, even if pressurized air is blown from the injection pipe 12, it is difficult to sufficiently remove the attached dust. When precoating the bag filter 10, the on-off valve 27 of the introduction duct 5 is closed, the on-off valve 24 of the return duct 23 is opened, and the dust in the hopper 22 of the pre-coating agent supply device is sucked by the suction action of the suction blower 14. ,
introduced into the filtration chamber 6 and attached to the bag filter 10,
Perform precoat. The pressure change at this time is shown in Figure B. When the pressure loss reaches a predetermined pressure (low pressure), the differential pressure detector 40b is activated, the on-off valve 24 is closed, and the on-off valve 27 of the introduction duct 5 is opened to introduce fume-containing air and perform a normal filtration action. The pressure change at this time is shown in Figure C. In this case, the fixed substances contained in the fume are adsorbed by the precoat agent, but this is volumetric filtration by the precoat agent, which is different from so-called surface filtration by the filter cloth, and the rate of increase in pressure drop is is small and has a gentle slope compared to line A. When the pressure loss reaches a predetermined pressure (high pressure), the differential pressure detector 40
a is activated, pressurized air is blown into the bag filter 10 from the injection pipe 12, and the adhering dust is peeled off by reverse injection and falls and accumulates in the hopper 8. This dust is discharged while maintaining airtightness by rotating the rotary valve 9, and is carried out by the transfer conveyor 3. After the cleaning by reverse injection is completed, the on-off valve 24 of the return duct 23
is released, the dust in the hopper 22 of the bricoating agent supply device is sucked by the suction blower 14, and precoating is performed in the same manner as described above. In this case, the on-off valve 27 of the introduction duct 5 may also be left open so that the pre-coating dust and the fume-containing air are sucked and the mixed air is sucked. Next, FIGS. 4 to 6 show a second embodiment. The dust collector 50 of this embodiment also has a dust collector body 51 similar to the previous example.
and a dust transfer conveyor 52. The dust collector main body 51 has an inner chamber partitioned by a partition wall 52 into a plurality of unit dust collectors, for example, four unit dust collectors 55a to 55d. Each unit dust collector has the same structure, and it also has the same structure as the dust collector main body 2 in the previous example, and the same parts are given the same symbols (some parts have suffixes a, b, c, etc.)
d) and the explanation will be omitted. Further, the dust transfer conveyor 52 is common to each unit dust collector, and an intermediate take-out g56 is provided at a suitable location, and a discharge part 60 is provided at the terminal end, and rotary valves 57 and 61 are attached to each, and the intermediate take-out part 56 is used for collecting dust. A hopper 58 is provided. 62 is a dust return duct, which is connected to branch return ducts 63a to 63d equipped with on-off valves 24a to 24d, and each branch return duct is connected to a branch introduction duct 6 connected to the introduction duct 5.
4a to 64d, and each branch introduction duct opens above the filtration chambers 6a to 6d as in the previous example. In the above configuration, backwashing and precoating are sequentially performed for each unit dust collector. First, the bag filter 10a is backwashed in the same manner as described above for the first unit dust collector 55a, and the hopper of the precoat agent supplying device is After that, the same backwashing and precoating operations are sequentially performed for each unit dust collector 55b to 55d. According to this embodiment, the fume generated from the fume generator 30 can be continuously and effectively sucked. [Effects of the Invention] The present invention has the following effects. Since the dust adhering to the filter cloth is peeled off and used as a pre-coat agent, the conventional trouble of purchasing, storing and transporting the pre-coat agent can be omitted, and pre-coating can be performed at low cost. In addition, when the collected dust is used for other purposes, there was a problem in the past because the pre-coating agent became a foreign substance and got mixed in, but with the present invention, since a part of the collected dust is used as a pre-coating agent, there is no chance of foreign substances getting mixed in. It is possible to use it as there is no such thing. Further, during pre-coating, by supplying the dust from above the filtration chamber, it is possible to easily and uniformly adhere the dust to the filter cloth in a short time. Furthermore, since the recovered dust is used as a pre-coating agent and a separate pre-coating agent as in the conventional method is not used, the amount of dust generated can be reduced. In addition, the dust collector body is divided into multiple unit dust collectors, and the filter cloth of each unit dust collector is cleaned, and a part of the dust is taken out from a common dust transfer conveyor, and this is supplied as a pre-coating agent to the above-mentioned unit dust collectors for pre-coating. By doing so, it is possible to continuously suck dust even when the dust suction of the unit dust collector is stopped, and it is possible to simplify the structure for taking out the dust as a precoating agent.

[Brief explanation of the drawing]

Figures 1 to 3 relate to the first embodiment; Figure 1 is an overall vertical sectional view, Figure 2 is a sectional view taken along line I-1 in Figure 1, and Figure 3 is the filtration resistance of the filter cloth. (Pressure loss) comparison graphs, Figures 4 to 6 are for the second embodiment, Figure 4 is an overall longitudinal sectional view, and Figure 5 is a cross-sectional view along the line ■-■ in Figure 4. , FIG. 6 is a sectional view taken along the line ■-■ in FIG. 1 and 50 are dust collectors, 2 and 51 are dust collector bodies, 3 is a dust transfer conveyor, 6.6a to 6d are yga chambers, 7.7a
-7d are purified air chambers, 10.10a-10d are bag filters, 20.56 are intermediate take-off parts, 23 are dust return ducts, 27.27a-27d are on-off valves, 55a-55d
is a unit dust collector, and P is a stripping means.

Claims (4)

[Claims] (1) Filter the supplied dust-containing air with a filter cloth,
A filter cloth characterized in that adhering dust is peeled off by a peeling means such as reverse jetting with pressurized air or applying vibration, the peeled off dust is collected, and a part of the collected dust is supplied as a pre-coat agent to the filter cloth for adhesion. Precoating method. (2) A dust collector main body equipped with a filter cloth that filters dust-containing air and a peeling means that peels off the dust adhering to the filter cloth, and an intermediate take-out section that receives and stores a part of the dust discharged from the main body. The intermediate take-out part is connected to the dust-containing air intake side of the dust collector main body via the return duct,
A dust collector characterized in that cleaning of a filter cloth by a peeling means and precoating by supplying stored dust through a return duct are performed in conjunction. (3) The main body of the dust collector is divided into a filtration chamber for introducing dust-containing air and a purification chamber for storing purified air formed on the side of the filtration chamber, and a filter cloth is provided in the filtration chamber as a bag filter and on the side of the purification chamber. 3. The dust collecting device according to claim 2, wherein the return duct for returning the stored dust is opened at the upper part of the filtration chamber. (4) The main body of the dust collector is divided into a plurality of unit dust collection chambers, each of which is equipped with a filtration chamber for storing a bag filter, a purification chamber for storing purified air, and means for peeling off dust attached to the bag filter, and a common peeling dust transfer conveyor. connected to
The conveyor is equipped with an intermediate take-out part that receives a portion of the transferred dust, and the intermediate take-out part is connected to the filtration chamber of each of the unit dust collection chambers via a switching valve, and each unit dust collection chamber is sequentially filtered by the stripping means. A dust collector characterized by cleaning a cloth and precoating it by supplying dust stored in an intermediate take-out section.