JPH06205918A - Operating method of filtration type dust collector - Google Patents

Abstract

PURPOSE:To provide the operating method of a filtration type dust collector in which dust collecting capacity is kept constant even when the added quantity of a neutralizer is changed, by controlling the period of dust blow-off by the added quantity of the alkali neutralizer based on the concentration of acidic gas. CONSTITUTION:In a filtration type dust collector where an alkaline neutralizer is added to waste gas based on the concentration of acidic gas in the waste gas to perform neutralization reaction, and to collect dust by a filter cloth, when the added quantity of the neutralizer is large, the period of dust blow-off is shortened and when the added quantity of the neutralizer is small, the period of dust blow-off is prolonged. When a charcoal fire is buried in ash in an incinerator, the deliquescence calcium chloride as a reactional product, is markedly generated to frequently cause the clogging of the filter cloth, and so the period of dust blow-off is shortened based on the information on the charcoal fire buried in ash. Further, when the difference in pressure between the waste gas inlet side and the treated gas outlet side becomes a prescribed value or more, dust blow-off operation is additionally performed by making an interruption on the period of dust blow-off. Thus, an operating method by which dust collecting capacity is kept constant irrespective of the added quantity of the neutralizer can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a filtration type dust collector, and more particularly to an acidic gas contained in a gas obtained by adding an alkali neutralizing agent to exhaust gas introduced into the filtration dust collector. The present invention relates to a method of operating a filtration type dust collecting apparatus, in which the water is neutralized and collected by a filter cloth of the filtration type dust collecting apparatus.

[0002]

2. Description of the Related Art In exhaust gas discharged from an incinerator,
Since it contains heavy metals, dioxins, etc., a filtration type dust collector is installed in the latter stage of the incinerator, and the heavy metals, dioxins, etc. are collected by this filtration type dust collector and the exhaust gas is released to the atmosphere. There is. However, the processing gas released from the filtration type dust collector contains acidic gases such as hydrogen chloride (HCl) and sulfur oxides (SOX), and these acidic gases are directly released to the atmosphere. It is not possible.

Therefore, an alkaline neutralizing agent such as calcium hydroxide [Ca (OH) ₂ ] is added to the exhaust gas introduced into the filtration type dust collector to neutralize the acid gas to carry out the filtration type collection. It collects on the filter cloth of the dust device. The addition amount of the alkali neutralizing agent is controlled based on the concentration of acidic gas in the processing gas discharged from the filtration dust collector.

However, calcium chloride (CaCl ₂ ) produced by the chemical reaction between hydrogen chloride and calcium hydroxide
Has a high deliquescent property (especially, the deliquescent property remarkably occurs when the temperature of the incinerator is lowered during a burial, etc.), so that deliquescent calcium chloride adheres to the filter cloth and frequently causes clogging. Therefore, conventionally, the filtration type dust collector is
Compressed air is blown to the filter cloth at a predetermined cycle to remove the dust containing calcium chloride attached to the filter cloth.

[0005]

However, since the conventional filtration type dust collector controls the dust removal operation at a constant cycle, for example, when the addition amount of the alkali neutralizing agent is increased, that is, when the chloride neutralizing agent is added, If the rate of adhesion of calcium to the filter cloth becomes faster, there is a drawback that calcium chloride is sufficiently adhered to the filter cloth before the dust removing operation, and the dust collecting ability is reduced during that time.

The present invention has been made in view of the above circumstances, and a method of operating a filtration type dust collecting apparatus capable of maintaining a constant dust collecting ability even when the amount of alkali neutralizer added changes. The purpose is to provide.

[0007]

In order to achieve the above-mentioned object, the present invention is a filter type dust collecting apparatus for treating exhaust gas discharged from an incinerator or the like and releasing it to the atmosphere. In a method for operating a filtration type dust collecting apparatus, which controls the addition amount of an alkali neutralizing agent added to the exhaust gas, based on the concentration of acid gas in the processing gas discharged from the dust collecting apparatus, It is characterized in that the dust removal cycle of the filtration type dust collecting apparatus is controlled based on the amount of addition of the solvating agent.

[0008]

According to the present invention, the dust removal cycle of the filtration dust collector is controlled based on the amount of the alkali neutralizing agent added. That is, when the addition amount is large, the dust removal period is shortened, and when the addition amount is small, the dust removal period is extended. Thereby, even if the amount of the alkali neutralizing agent added changes, the dust collecting ability can be maintained constant.

Calcium chloride (Ca) produced by a chemical reaction between an acidic gas such as hydrogen chloride (HCl) and an alkali neutralizing agent such as calcium hydroxide [Ca (OH) ₂ ].
Cl ₂ ) has a remarkable deliquescent property particularly when the temperature of the incinerator is lowered during the burial of the incinerator or the like. Therefore, when the burial of the incinerator or the like is performed, the dust removal cycle is controlled to be even shorter and substantially intermittent.

As a result, the dust collecting capability at the start of the next operation of the incinerator is not reduced. Furthermore, the differential pressure between the exhaust gas inlet side and the treated gas outlet side of the filtration type dust collector is measured, and when this differential pressure exceeds a predetermined value, it is interrupted in the dust sweep cycle to perform the dust sweep operation. I do.

As a result, the dust collecting ability can be maintained constant without being affected by the amount of the alkali neutralizing agent added.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a method for operating a filtration type dust collecting apparatus according to the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a treatment system for incinerator exhaust gas to which the method for operating a filtration dust collector according to the present invention is applied.

The combustion exhaust gas generated from the incinerator 10 is
By being sucked by the intake fan 12, the air is discharged from the chimney 20 to the atmosphere through the flue 14, the filtration dust collector 16, and the flue 18. The inlet side flue 14 of the filtration type dust collector 16 is provided with a blowing part 22. This blowing part 2
An alkaline neutralizing agent for neutralizing an acidic gas such as hydrogen chloride contained in the exhaust gas, for example, calcium hydroxide, is supplied to 2. As a result, calcium hydroxide is added to the exhaust gas, and calcium chloride produced by the addition is added to the filter cloth 24A of the filtration dust collector 16,
It adheres to 24B and 24C and deliquesces.

The calcium hydroxide is stored in the silo 26, and a necessary amount based on the opening / closing amount is cut out from the silo 26 by a feeder 30 whose opening / closing amount is inverter-controlled by a computing unit 28. The cut out calcium hydroxide is pneumatically transported to the blow-in unit 22 by a transportation blower 32 installed at a subsequent stage of the feeder 30. Based on the information indicating the concentrations from the hydrogen chloride densitometer 34 and the sulfur oxide densitometer 36 connected to the outlet side flue 18, the computing unit 28 uses calcium hydroxide to bring these concentrations close to zero. Calculate the addition amount of. And the calculation unit 2
Reference numeral 8 outputs a drive signal to the supply device 30 for cutting out the addition amount calculated and calculated. As a result, the amount of calcium hydroxide added is automatically controlled based on the concentration of acidic gas contained in the process gas from the filtration dust collector 16.

On the other hand, the amount of calcium hydroxide cut out by the feeder 30 is output to the controller 38.
The controller 38, based on the cutout amount,
The open / close cycle of the air valves 40A, 40B, 40C is calculated. Then, the controller 38 outputs drive signals for opening and closing the air valves 40A, 40B, 40C at the calculated open / close cycle to the air valves 40A, 40B,
Output to 40C. As a result, the air valve 40A,
The opening and closing operations of 40B and 40C are controlled by the controller 38.

The air valves 40A, 40B, 40C
An air source 42 is connected to. Compressed air from the air source 42 is released by the air valves 40A, 40B, 4
It is supplied into the filter cloths 24A, 24B, and 24C via 0C. As a result, the dust attached to the filter cloths 24A, 24B, 24C is removed. In addition, the controller 38
When the burial signal 44 indicating the burial of the incinerator 10 is input, the air valve 4 outputs a drive signal for intermittently opening the air valves 40A, 40B and 40C in a short cycle.
It can be output to 0A, 40B, and 40C.

Further, information indicating the differential pressure between the flue 14 and the flue 18 is sequentially output from the pressure differencer 46 to the controller 38. This differential pressure is a predetermined value (filter cloth 24A, 24
B, 24C is a value indicating that the trapping ability has deteriorated) or more), a drive signal for opening the air valves 40A, 40B, 40C is supplied to the air valves 40A, 40B, 4
Can be output to 0C.

Next, a method of controlling the operation of the filtration type dust collector 16 by the controller 38 will be described with reference to FIG. First, the incinerator 10 and the filtration dust collector 1
Operation of 6 is started. Then, the hydrogen chloride concentration and the sulfur oxide concentration in the treated gas passing through the flue 18 are measured by the hydrogen chloride concentration meter 34 and the sulfur oxide concentration meter 36, respectively, and the addition amount obtained based on these concentrations Of calcium hydroxide is supplied from the silo 26 to the blowing section 22.

Since the hydrogen chloride concentration and the sulfur oxide concentration during the initial operation period may be higher than the respective concentrations during the steady operation period, the addition amount of the calcium hydroxide is controlled and controlled by the arithmetic unit 28 in a large amount. It Thus, as shown in FIG. 2, the controller 38 controls the opening and closing of the air valves 40A, 40B, 40C at a cycle T ₁ shorter than the dust removal cycle T ₂ during the steady operation period.

Thus, before the deliquescent calcium chloride is sufficiently adhered to each of the filter cloths 24A, 24B and 24C, calcium chloride and other dusts are removed from the filter cloths 24A, 24B and 24C.
Can be paid off from C. Therefore, even if the amount of calcium hydroxide added is increased, the dust collecting ability can be maintained constant. Next, during the steady operation period, the controller 38 controls the opening / closing of the air valves 40A, 40B, 40C at the cycle of T ₂ to wipe off the dust, as described above.

During the steady operation period, the differential pressure device 4 shown in FIG.
When the differential pressure measured in 6 exceeds a predetermined value, the controller 38 causes the air valves 40A, 40B and 40C to open at substantially the same time as it interrupts the cycle T ₂ . This makes it possible to maintain the dust collecting capability of the filtration dust collector 16 constant without being affected by the amount of calcium hydroxide added. In addition, the cycle T during the steady operation period
₂ is no longer than the longest period previously stored in controller 38.

Next, the controller 38 controls the flash signal 4
When 4 is input, the air valve 40A in Umahi operation period in the period T _3, 40B, 40C closing control to the brushing dust performed. This is because the deliquescent property of calcium chloride occurs remarkably during the temperature decrease period during the burial of the incinerator 10, so that the dust removal cycle is controlled to be substantially shorter and shorter than the T ₁ and T ₂ cycles, The deliquescent calcium chloride was efficiently removed.

As a result, the dust collecting capability at the time of starting the next operation of the incinerator 10 is not lowered.

[0024]

As described above, according to the method of operating the filtration type dust collecting apparatus of the present invention, the dust removing cycle of the filtration type dust collecting apparatus is controlled based on the addition amount of the alkali neutralizing agent. Therefore, even if the addition amount of the alkali neutralizing agent changes, the dust collecting ability can be maintained constant.

Calcium chloride and the like produced by a chemical reaction between an acid gas and an alkali neutralizing agent have a remarkable deliquescent property particularly when the temperature of the incinerator is lowered during the burial of the incinerator. At the time of burial, the dust removal cycle is controlled to be shorter and substantially intermittently. As a result, the dust collection capability at the start of the next operation of the incinerator is not reduced.

Further, the differential pressure between the exhaust gas inlet side and the treated gas outlet side of the filtration type dust collector is measured, and when the differential pressure exceeds a predetermined value, the dust is removed by interrupting the dust sweeping cycle. Since the removal operation is performed, the dust collecting ability can be maintained constant without being affected by the addition amount of the alkali neutralizing agent.

[Brief description of drawings]

FIG. 1 is a processing system diagram of a method for operating a filtration dust collector according to the present invention.

FIG. 2 is a diagram showing a dust removal cycle of the operation method of the filtration dust collector according to the present invention.

[Explanation of symbols]

 10 ... Incinerator 12 ... Intake fan 14, 18 ... Flue 16 ... Filtration type dust collector 22 ... Blowing part 24A, 24B, 24C ... Filter cloth 26 ... Silo 28 ... Calculation part 30 ... Feeder 34 ... Hydrogen chloride concentration meter 36 ... Sulfur oxide concentration meter 38 ... Controller 40A, 40B, 40C ... Air valve 44 ... Burst signal 46 ... Differential pressure device

Claims (3)

[Claims] 1. A filter-type dust collector that treats exhaust gas discharged from an incinerator or the like and discharges it to the atmosphere, based on the concentration of acidic gas in the process gas discharged from this filter-type dust collector. In the operating method of the filtration type dust collector controlling the addition amount of the alkali neutralizing agent added to the exhaust gas, based on the addition amount of the alkali neutralizing agent, A method for operating a filter-type dust collector, which is characterized in that a cycle for removing dust is controlled. 2. The method of operating a filtration type dust collecting apparatus according to claim 1, wherein the dust removal cycle is controlled based on information indicating a buried fire in the incinerator or the like. 3. The differential pressure between the exhaust gas inlet side and the treated gas outlet side of the filtration type dust collector is measured, and when the differential pressure exceeds a predetermined value, it is interrupted in the dust sweep cycle. The method for operating a filtration type dust collecting apparatus according to claim 1, wherein the dust removing operation is controlled.