JP2520558B2 - Operation control method of precoat type bag filter device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag filter device for separating dusts and suspended solids from a gas stream and removing or collecting the dusts, and particularly to a precoat for forming a precoat layer on the surface of a filter cloth before performing a filtering operation. Type bag filter device.

[0002]

2. Description of the Related Art Among the types of bag filter devices currently in practical use, the most widely used type is a filter cloth on which a chemical agent that controls filtration and neutralization of acidic harmful gas is entrained in exhaust gas. This is a method in which the dust layer formed of dust and chemicals accumulated on the filter cloth is wiped off by the pulse jet method as the operation is continued.

The structure of the filtration chamber includes both a single chamber structure and a multi-chamber structure. In this document, a pulse jet type multi-chamber structure type exhaust gas entrainment system will be described as a typical example of the prior art.

6 and 7 show a schematic structure of a conventional bag filter device.

In FIGS. 6 and 7, reference numeral a denotes a casing which houses a unit dust collecting mechanism which constitutes a bag filter device and separates the unit from each other. Each unit dust collecting mechanism suspends a plurality of filter cloths b. The partition plate c divides the filter chamber d in the lower part and the clean gas chamber e in the upper part into two parts.

In the clean gas chamber e, a plurality of nozzles f1 for injecting compressed air in a jet pulse shape into each filter cloth b through an opening / closing valve connected to an air compression source (not shown).
An air blow-in pipe f provided with is provided.

A hopper chamber h for collecting dust is formed below the filtration chamber d, and a discharge mechanism j for discharging dust is connected to the bottom of the hopper chamber h.

On the outer side surface of the hopper chamber h, a main flue k for introducing combustion gas containing soot and acidic harmful gas generated in an incinerator or a combustion furnace (not shown) is arranged. In the middle of the process, the chemical m for neutralization transported from a harmful gas removing device (not shown) is continuously supplied.
Is mixed with combustion gas to form exhaust gas g.

Exhaust gas g flows into each hopper chamber h from a main flue k through a branch introduction duct p branched for each unit dust collecting mechanism, and acidic harmful gas and chemical m contained therein are separated. While reaching the neutralization reaction, it reaches the surfaces of the plurality of filter cloths b suspended in the filtration chamber d.

The unit dust collecting mechanism after the completion of the cleaning work, which will be described later, has a low ventilation resistance, so that a larger amount of the exhaust gas g flows into the unit than the other sections in continuous operation, and when it passes through the filter cloth b, its filtration is performed. Depending on the ability, the reacted and unreacted drugs m are filtered and attached to the surface, and the drug layer b1 (see FIG. 7) is formed by the partially reacted drugs m, which is the main component of the filtration / neutralization work.

In the subsequent passing of the gas, the acidic harmful gas remaining in the exhaust gas g causes a neutralization reaction with the unreacted drug m in the drug layer b1, and the soot and dust that have come flying with the exhaust gas g and the reaction completion. And the unreacted drug m are sequentially deposited on the surface of the drug layer b1 to form a dust layer b2 (see FIG. 7).

Therefore, when the exhaust gas g passes through the dust layer b2 and the drug layer b1, the retained dust is captured, and the residual acidic harmful gas comes into contact with the unreacted drug m, thereby efficiently Neutralization reaction and clean gas n
And is discharged to the clean gas chamber e.

The clean gas n passes through a clean gas on-off valve r inserted in a branch discharge duct q arranged on the outer surface of the clean gas chamber e, passes through a discharge main duct s, and is sucked into an unillustrated draft fan. Then, it is released into the atmosphere from a chimney (not shown).

When the operation is continued in this state, the dust layer b2 gradually grows due to the dust and the reacted and unreacted chemicals m in the combustion gas that continues to fly, and the ventilation resistance increases. Therefore, by closing the clean gas on-off valve r of the corresponding unit dust collecting mechanism to stop the inflow of the exhaust gas g, and then jetting the compressed air from the air blowing pipe f,
The drug layer b1 attached to the surface of the filter cloth b and the accumulated dust layer b2 are peeled off and dropped. After that, the clean gas on-off valve r is opened again to restart the inflow of the exhaust gas g.

By sequentially performing this cleaning operation for each unit dust collecting mechanism, the dust collected on the filter cloth of the unit dust collecting mechanism and the collected ash consisting of the reacted and unreacted chemicals m and the like are collected. Can be removed. The hopper room h
The collected ash that has fallen to is discharged to the outside by a discharging mechanism j.

[0016]

In the case of the conventional multi-chamber structure type exhaust gas entrainment type bag filter device, the chemicals m forming the chemical layer b1 are collectively contained in the main flue k or the pre-reaction tower (not shown). Is being supplied.

Therefore, as described above, if the unit dust collecting mechanism having the increased ventilation resistance is removed, the ventilation resistance of the section is reduced all at once, so that the exhaust gas g intensively flows into the section. A large amount of drug m is accompanied, but drug layer b1
The flow rate of the exhaust gas to the section gradually decreases with the growth of, and the amount of entrained drug also automatically decreases. Furthermore, as the exhaust gas flow rate decreases, the attachment rate of the chemical m on the filter cloth b decreases,
The majority of the drugs m fall into the hopper chamber h without reacting.

On the other hand, since the medicine m is continuously supplied, a part of the medicine m is immediately discharged to the other section.
Since all is supplied to each section during steady operation, the unreacted drug m that is continuously supplied after the drug layer b1 is formed is an excess amount, which promotes the increase of the dust layer b2.

Therefore, the ventilation resistance increases faster, so that the interval for removing the particles is shortened, and a large amount of the unreacted drug is discharged in combination with the increase in the amount of the dropped drug. As a result, not only the drug cost increases, but also heavy metals and dioxins are added. Since the amount of collected ash (exhaust ash) designated as “specially controlled waste” is increased due to the inclusion of toxic substances of the same class, the post-treatment cost will increase.

Moreover, even when the inflow of exhaust gas g is small due to the combustion condition and the like, all the filter cloths b and the surrounding metal fittings are exhausted to exhaust gas g because the gas is passed through all of the constituent dust collecting mechanisms. Since they are in constant contact with each other, due to the dew condensation caused by the temperature decrease after the operation is stopped, the partial removal of moisture due to the moisture absorption and adhesion of the chemical layer b1 to the filter cloth b and the influence of the corrosion of the peripheral metal fittings and the like are all caused. The unit dust collection mechanism will receive it.

[0021]

The operation control method of the precoat type bag filter device of the present invention is constituted by a plurality of unit dust collecting mechanisms consisting of a clean gas chamber, a filtration chamber and a hopper chamber, and is provided before the filtration work. A method for controlling the operation of a precoat type bag filter device in which a precoat layer is previously formed on the surface of the filter cloth installed in the filtration chamber in the step, wherein the plurality of unit dust collecting mechanisms flow into these unit dust collecting mechanisms. When a precoat layer is formed on the filter cloth of one of the plurality of unit dust collecting mechanisms, the flow rate value of the gas flowing into the unit dust collecting mechanism is When it is lower than the set amount, the gas is prevented from flowing into at least one other unit dust collecting mechanism.

In addition, in the operation control method of the above-mentioned precoat type bag filter device, it is assumed that the amount of exhaust gas generated is roughly determined by the quality and quantity of the material to be burned during the unit operation period,
Among the plurality of unit dust collecting mechanisms, the number of operations of each unit dust collecting mechanism is selected so that the exhaust gas amount of the rated amount or an amount not significantly lower than the rated amount can flow.

[0023]

When the precoat layer is formed on the filter cloth having one unit dust collecting mechanism, if the flow rate of the gas flowing into the unit dust collecting mechanism is lower than the set amount, at least one other dust collecting mechanism is used. By preventing the gas from flowing into the unit dust collecting mechanism, a gas of a set amount or more is caused to flow into one unit dust collecting mechanism at the time of forming the precoat layer, and the chemical is adhered to the filter cloth surface at high speed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a schematic structure of a precoat type bag filter device for carrying out the operation control method of the precoat type bag filter device according to the present invention, and FIG. 3 shows a schematic flow of this device. It should be noted that in FIG. 3, each unit dust collecting mechanism is indicated from the left side, and if necessary, each reference numeral of each component disposed in each unit dust collecting mechanism, is followed by the number of the unit dust collecting mechanism. By attaching the reference numeral, each component is distinguished by setting the reference numeral to three digits.

In FIG. 1 and FIG. 2, reference numeral 1 is a casing for accommodating a plurality of unit dust collecting mechanisms constituting a precoat type bag filter device, and each unit dust collecting mechanism suspends a plurality of filter cloths 2. The partition plate 3 divides the upper clean gas chamber 4 and the lower gas inflow chamber 5.

The clean gas chamber 4 is a space that communicates with the gas inflow chamber 5 via a plurality of filter cloths 2. Each clean gas chamber 4 has a branch duct 41 and a clean gas on-off valve 42. It is connected to a common clean gas duct 43 and is connected to an unillustrated induction fan.

In the clean gas chamber 4, one air blowing pipe 6 is provided for each row of the plurality of filter cloths 2, and the air blowing pipe 6 is connected to the air header 62 through the air opening / closing valve 61. And is connected to a compressed air source (not shown).

Further, at the lower part of the air blowing pipe 6, a nozzle 6 for blowing blown compressed air into the plurality of filter cloths 2 is provided.
The filter cloth 3 is disposed so as to face the opening of the filter cloth 2. The air blowing pipe 6, the air opening / closing valve 61, the air header 62, the nozzle 63, and the compressed air source constitute a dust removing mechanism.

The gas inflow chamber 5 is divided into a plurality of filtration chambers 51 partitioned by a plurality of partition walls 11 and a hopper chamber 52 which is continuous below the filtration chambers 51 and is also partitioned. A dust discharging mechanism 53, which is common to each unit dust collecting mechanism for discharging dust and the like separated and dropped from the filter cloth 2, is connected to the lower portion.

A main flue 7 is constructed outside the plurality of hopper chambers 52. From the main flue 7 to each hopper chamber 5.
A branch flue 71 leading to 2 is piped.

A dust-containing gas introduction duct is constituted by the main flue 7 and the branch flue 71 described above. In each hopper chamber 52, soot and acidic harmful gas generated in an incinerator or a combustion furnace (not shown). Exhaust gas 81 including the like flows in.

Further, a medicine supply port 93 is provided in each hopper chamber 52.
Are formed respectively. At the medicine supply port 93, a branch pipe 91a branched from the medicine pipe 91 is provided.
2, the neutralizing chemical 9 such as slaked lime is transported from a harmful gas removing device (not shown) through the chemical piping 91, and its supply is controlled by opening and closing the chemical supply valve 92. . A medicine supply means is constituted by the medicine pipe 91, the medicine supply valve 92, the medicine supply port 93 and the harmful gas removing device.

Further, as shown in FIG. 3, the clean gas duct 43 is provided with a total gas flow meter 44 for measuring the discharge amount of all the clean gas discharged through the clean gas duct 43, and each branch. Ducts 411, 412, 41
3 is provided with flow meters 451, 452, 453 for measuring the flow rate of the clean gas for each unit dust collecting mechanism.

Next, in the case where the operation control method of the present invention is carried out by the precoat type bag filter device constructed as described above, regarding the operation from the filtering work to the removal and the precoat layer formation to the restart of the filtration work. 4 will be described with reference to the flowchart of FIG.

First, in step S1, the quality of the burned material during the unit operation period is used to estimate the amount of exhaust gas to be generated, and the rated amount of each unit dust collection mechanism is calculated. The number of operations of each of the unit dust collecting mechanisms is selected so that the exhaust gas amount that does not fall significantly below the rated amount can be flown (step S2). Here, the rated amount means the amount of exhaust gas with which each unit dust collecting mechanism can efficiently perform the filtering operation.

This is because the quality and quantity of the incinerated material often change depending on the operation period. Especially, in the case of the refuse incinerator, there are many seasonal fluctuations, and further improvement of the quality of the waste and increase in the amount of waste treated. The things that are designed and manufactured in anticipation overlap,
This is because the amount of generated gas is often 1/2 to 2/3 of the rated amount.

Therefore, as in the prior art, even when the amount of inflow of exhaust gas is small due to the combustion condition and the like, in the case where gas is passed through all of the unit dust collecting mechanisms that constitute it, each filter cloth and all the surrounding metal fittings, etc. You are in constant contact with the exhaust gas,
Condensation caused by the temperature drop after the operation is stopped affects all unit dust collection mechanisms due to failure to wipe off due to moisture absorption and sticking of a part of the chemical layer on the filter cloth and corrosion of peripheral metal fittings. , 1/3 of the unit dust collection mechanism as in this example
By suspending the unit for a while and putting it in the standby state, the unit dust collection mechanism can be used alternately, and in addition to the maintenance and management of the suspended section, long-term stable operation is possible and the filter cloth due to moisture absorption is used. It is possible to prevent failure of cleaning and corrosion of peripheral fittings.

In this example, as a result of the selection described above, FIG.
It is assumed that the unit dust collection mechanisms of 3 chambers each shown in are operating.

Next, after selecting the operation number of the unit dust collecting mechanism in this way, each clean gas on-off valve 421, 422, 42
Exhaust gas 81 from the dust-containing gas introduction duct by opening 3
1,812,813 to hopper chambers 521,522,523
Inflow to each. At this time, each filtration chamber 51
The precoat layer 21 (see FIG. 5) is formed in advance on each of the filter cloths 201, 202, 203 of 1, 512, 513 by supplying the neutralizing agent 9.

Then, as described above, the hopper chambers 521,
Exhaust gas 811 and 81 flowing into 522 and 523, respectively
2, 813 rises to form a plurality of filter cloths 201, 202, 2
When passing through the precoat layer 21 formed on the surface of No. 03, the retained dust is filtered and the acidic harmful gas contained therein is removed by the neutralizing action with the neutralizing agent 9. 822, 823, and are discharged into the clean gas chambers 401, 402, 403, respectively.
Branch ducts 411, 412, 413, clean gas on-off valve 4
After passing through 21, 422 and 423, it is discharged from the clean gas duct 43 into the atmosphere from a chimney (not shown) through an induction fan (not shown) (step S3). At this time, the flow meter 45
1,452,453 to branch ducts 411,412
The total flow rate of the clean gas passing through the clean gas duct 43 is measured while the total flow rate of the clean gas passing through the clean gas duct 43 is measured by the total gas flow meter 44.

As the filtration work is continued, as shown in FIG. 5, the dust layer 22 is formed on the surface of the precoat layer 21 to form the dust layer 22. Therefore, the dust layer 22 and the precoat layer 22 are formed at a predetermined stage. The work of removing the layer 21 is required. This is to judge whether or not any of the unit dust collecting mechanisms has to perform the payoff in step S4. Specifically, for example, the differential pressure between the inside and outside of the filter cloth 2 in the filter chamber 5 of each unit dust collection mechanism is measured by a differential pressure gauge, and it is determined whether or not this differential pressure exceeds a set value. .

In one unit dust collecting mechanism (for example, the unit dust collecting mechanism in FIG. 3), when the differential pressure exceeds the set value due to the increase of the ventilation resistance of the exhaust gas 81, the process proceeds to step S5, and the like. It is judged whether the unit dust collecting mechanism of is in the process of removing the dust, and if the other unit dust collecting mechanisms are not in the process of removing dust, the clean gas on-off valve 422 of the unit dust collecting mechanism is set in step S6. It is closed to block the flow of the exhaust gas 812 into the filtration chamber 512.

Subsequently, the air opening / closing valve 612 corresponding to the filtration chamber 512 is opened, and compressed air from a compressed air source (not shown) is discharged from the nozzle 63 through the filter cloth 20 in the filtration chamber 512.
If a jet is injected into 2 for a short time, the clean gas chamber 402
The clean gas 822 inside becomes a secondary airflow induced by the jet jet, and flows back into the filter cloth 202 together with the jet air, and the precoat that adheres to the surface of the filter cloth 202 due to the shock wave of the jet jet and the backflow effect of the secondary airflow. The collected ash composed of the layer 21 and the dust layer 22 can be peeled off. If this injection is performed on all the rows of the filter cloth 202 group provided in the unit dust collecting mechanism, the work of removing the unit dust collecting mechanism is completed (step S7).

Here, as a process of the above-mentioned scrubbing work, in the unit dust collecting mechanism in the center of FIG.
The filter cloth 2 at the left end is in a state where the inflow of the exhaust gas 81 is stopped and the collected ash composed of the precoat layer 21 and the dust layer 22 is attached, and the filter cloth 2 at the center opens the air opening / closing valve 61 to open the nozzle 63. It shows a state in which compressed air is jetted from the above to separate the collected ash, dust is falling, and the filter cloth 2 at the right end has finished the above-mentioned wiping operation.

The separated collected ash is collected in the hopper chamber 52.
After being deposited on the bottom of the, the dust is discharged to the outside by the dust discharging mechanism 53.

When the cleaning operation is completed, the clean gas on-off valve 422 of the unit dust collecting mechanism is opened to start the flow of the exhaust gas 812 into the unit dust collecting mechanism again (step S8). Since the ventilation resistance of the exhaust gas 812 passing through the filter cloth 202 in the state where the cleaning operation is completed is reduced, the amount of the exhaust gas attracted to the unit dust collection mechanism is in a state of being increased from that before the cleaning.

At this time, in step S9, the filter cloth 20
The amount of gas passed through 2 is measured by the flow meter 452, and it is determined whether or not the amount of gas is equal to or greater than the set amount. The set amount is set in advance so that the drug is efficiently adsorbed on the filter cloth when the precoat layer is formed. If the gas amount is equal to or larger than the set amount, the process proceeds to step S10, the medicine supply valve 922 is opened, and the medicine 9 for neutralization is injected from the medicine supply port 932 all at once. As a result, the medicine 9 rises, is adsorbed on the surfaces of the plurality of filter cloths 202, and the precoat layer 21 is reformed in a short time, and the drop rate of the medicine 9 during this period is extremely small (step S11).

When the work of forming the precoat layer 21 is completed in this way, the chemical supply valve 922 is closed, the clean gas on-off valve 422 is opened, and the process returns to step S3 to proceed to the normal filtration work.

If the gas amount is less than the set amount in step S9, the flow proceeds to step S12, and the gas amounts of the other unit dust collecting mechanisms and the gas amount of the unit dust collecting mechanism are also measured. , 452, 453, and the clean gas on-off valve 423 of the unit dust collecting mechanism (for example, the unit dust collecting mechanism) showing the minimum gas amount is closed. As a result, the exhaust gas flow rate of the unit dust collection mechanism that has finished being removed increases, and if the gas amount exceeds the set amount due to this increase, the process proceeds to step S10 and the chemical supply valve 92
2 is opened, and the neutralizing chemical 9 is sprayed from the chemical supply port 932. At this time, since the clean gas on-off valve 423 of the unit dust collection mechanism is closed, a large amount of exhaust gas is flowing into the unit dust collection mechanism, and the chemicals are entrained in the large amount of accelerated exhaust gas 812. 9 rises without dropping and reforms the precoat layer 21 efficiently in a short time.

Even if the clean gas on-off valve 423 of the unit dust collecting mechanism is closed, if the gas amount is below the set amount,
The clean gas on-off valve 421 of the unit dust collecting mechanism is also closed to further increase the flow rate of exhaust gas flowing into the unit dust collecting mechanism.

When the work for forming the precoat layer 21 is completed, the chemical supply valve 922 is closed and the clean gas on-off valves 422 and 423 are opened, as described above, and step S3 is performed.
Then, the process returns to the normal filtration operation in which the gas flow rate is returned to the predetermined value.

Such an operation is sequentially performed for each filtration chamber 51 of each unit dust collecting mechanism.

In this example, the condition for starting the cleaning operation was explained by increasing the ventilation resistance. However, an exhaust gas concentration meter is installed in the clean gas chamber 4 or the clean gas duct 43 so that the reaction of the neutralizing agent can be prevented by the neutralizing action. The end may be detected or may be performed in combination with an increase in ventilation resistance.

As described above, the cleaning work is performed by increasing the ventilation resistance due to the accumulation of dust and the completion of the neutralization reaction of the chemicals, and if the precoat layer thickness is set systematically, only the reacted chemicals are discharged. In addition to the efficient use of chemicals, the amount of collected ash to be discharged can be reduced, so that the post-treatment cost of collected ash that causes secondary pollution can be reduced.

Further, in this example, the other unit dust collecting mechanism which stops when forming the precoat layer in one unit dust collecting mechanism is the unit dust collecting mechanism in which the amount of exhaust gas is the minimum. Not limited to this, any unit dust collection mechanism may be stopped.

Further, the mounting positions of the flow meters 451, 452, 453 may be before or after the clean gas on-off valves 421, 422, 423.

Although the chemical supply port 92 is formed in the hopper chamber 52, it may be arranged in the middle of the branch flue 71, and the clean gas on-off valve 42 is provided for controlling the exhaust gas inflow. An exhaust gas opening / closing damper may be provided in the road 71.

[0059]

As described above, according to the present invention, 1
When the precoat layer is formed on the filter cloth of one unit dust collecting mechanism, if the flow rate value of the gas flowing into the unit dust collecting mechanism is lower than the set amount, at least one other unit dust collecting mechanism. Since this is a method of preventing the inflow of gas into the precoat layer, it is possible to inject more than a preset amount of gas into one unit dust collection mechanism at the time of forming this precoat layer and adhere the drug to the filter cloth surface at high speed. It is possible to improve the adherence rate of the non-reacted drug and prevent the conventional large discharge of the unreacted drug.

Further, since the number of unit dust collecting mechanisms to be used is selected according to the amount of gas generated before the start of operation,
Filtration work is performed near the rated value with good performance,
The effect of prolonging life can be exhibited by reducing the range of influence of dust failure or the like due to moisture absorption and sticking to the filter cloth and corrosion of peripheral fittings. In addition, if one unit dust collection mechanism fails, the unit dust collection mechanism that is not operating will always be in operation, so long-term stable operation is possible in combination with maintenance of the unit dust collection mechanism that is not operating. become.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view showing a schematic configuration of a precoat type bag filter device for carrying out an operation control method of a precoat type bag filter device according to the present invention.

FIG. 2 is a composite view showing a front view and a partial broken surface showing a schematic configuration of a precoat type bag filter device for carrying out an operation control method of the precoat type bag filter device according to the present invention.

FIG. 3 is a diagram showing a schematic flow of the present apparatus.

FIG. 4 is a flowchart illustrating an operation control method of a precoat type bag filter device according to the present invention.

FIG. 5 is an enlarged view showing a state of adhesion / accumulation on the surface of the filter cloth.

FIG. 6 is a side sectional view showing a schematic configuration of a conventional bag filter device.

7 is a cross-sectional view taken along the line AA in FIG.

[Explanation of symbols]

 2 Filter cloth 21 Precoat layer 4 Clean gas chamber 51 Filtration chamber 52 Hopper chamber 451, 452, 453 Flowmeter

Claims (2)

(57) [Claims] 1. A precoat layer is preliminarily formed on the surface of a filter cloth which is composed of a plurality of unit dust collecting mechanisms consisting of a clean gas chamber, a filtration chamber and a hopper chamber, and which is installed in the filtration chamber before the filtration work. A method for controlling the operation of a precoat type bag filter device to be formed, wherein the plurality of unit dust collecting mechanisms are provided with measuring devices for measuring the flow rates of gas flowing into these unit dust collecting mechanisms, respectively, and When forming the precoat layer on the filter cloth of one unit dust collecting mechanism, if the flow rate value of the gas flowing into the unit dust collecting mechanism is lower than the set amount,
A method for controlling operation of a precoat type bag filter device, characterized in that gas is prevented from flowing into at least one other unit dust collecting mechanism. 2. The operation control method for a precoat type bag filter device according to claim 1, wherein the quantity of exhaust gas to be generated is estimated by the quality and quantity of the material to be burned during a unit operation period, and the plurality of the plurality are constructed. Pre-coated bag filter device characterized by selecting the number of operations of each unit dust collecting mechanism so that the exhaust gas amount of each unit dust collecting mechanism can be made to flow to a rated amount or a value not significantly lower than the rated amount. Operation control method.