JPH09299732A - Precoat bag filter equipped with guide vane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precoat bag filter equipped with a guide vane in which required chemicals cost and ash treating cost are reduce by properly feeding chemicals, a blow-off period is extended and the lowering of efficiency immediately after it is prevented. SOLUTION: In the position opposite to a waste gas introducing port 21 of a waste gas duct 2 from which waste gas 3 or a gaseous mixture into which chemicals 6 have been blown is sent into a bag filter 1, a guide vane 4 freely ratable in the vertical directions is installed. When a precut layer is formed, the guide vane 4 is positioned upward to raise the gaseous mixture 31 to a filter cloth group 12 and also an upward angle of the guide vane 4 is displaced to raise the chemicals in a uniform distribution state. When filtration work is executed, the guide vane 4 is positioned downward and after the waste gas 3 is once made to descend, it is turned upward to raise it to the filter cloth group 12 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment facility for neutralizing acidic harmful gas in exhaust gas generated from an incinerator, a combustion furnace or the like, and also for promoting and removing dust and the like.

[0002]

2. Description of the Related Art Of the bag filter devices currently in practical use, those most often used for waste incineration facilities are chemicals such as slaked lime that neutralize acidic harmful gases and filter solids. It is attached to the filter cloth by being entrained in the combustion gas.If the dust layer consisting of chemicals, dust, etc. that continues to fly and accumulates on the filter cloth increases the ventilation resistance, the dust layer is sprayed with a pulse jet. This method is a drop method, and this method will be described as a typical example of the conventional method.

FIG. 5 is a diagram showing an outline of a bag filter device which has been conventionally used. In FIG. 5, a high-temperature combustion gas containing acidic harmful gas and dust generated in an incinerator (not shown) is cooled by a gas cooling device (not shown) and then enters the pre-absorption reaction section a to absorb the acidic harmful gas. The medicine b is jetted.

[0004] Air This agent b is stored in the drug reservoir c _1, the dispensing feeder c ₂ and blow blower c ₃ installed at the bottom of the drug reservoir c _1, to the front absorption reaction section a Be transported. The chemical storage tank c ₁ , the fixed amount supply feeder c ₂ and the blower blower c ₃ constitute a harmful gas removing device c.

Inside the pre-absorption reaction section a, the chemical b continuously supplied from the harmful gas removing device c reacts with the acidic harmful gas in the combustion gas to some extent, but most of the chemical b remains unreacted. The exhaust gas d in this state is sent to the bag filter device f in the exhaust gas duct e.

That is, the exhaust gas d entering the bag filter device f contains some of the reaction products and most of the unreacted chemicals together with the acidic harmful gas and dust generated in the incinerator. .

[0007] The dust and reaction products and unreacted drug in the exhaust gas d, filtered through a bag filter device filtering chamber f ₁ within a plurality of filter cloth f ₂ which is suspended on the f, the surface of the filter cloth f ₂ It adheres to and forms a dust layer, and grows gradually.

On the other hand, the acidic harmful gas contained in the exhaust gas d causes a post-absorption reaction with the unreacted drug in the dust layer,
Along with the above-described filtering work, the exhaust gas d that has passed through the filter cloth portion becomes the clean gas g, which is discharged from the clean gas chamber f ₃ to the atmosphere from the chimney s through the induced draft fan h.

When the above-described operation is continued, the chemical agent b and the dust that continue to fly are gradually accumulated, so that the ventilation resistance of the dust layer is gradually increased and the exhaust gas d becomes difficult to pass through.

The state is indicated by an internal / external differential pressure detector k of the filter cloth f _2.
If the differential pressure exceeds the set value, the controller i instructs the blower device j for each row of the plurality of filter cloths f _{2 in} the passing gas according to a fixed order and interval. A general measure is to eject a pulse jet air flow to separate the dust layer.

The dust that has been separated and dropped, that is, the collected ash, is discharged from the hopper f ₄ to the outside by the discharging means f ₅ .

[0012]

However, according to the above-mentioned conventional method, since the main force of neutralizing the acidic harmful gas and the dust filtration is the dust layer formed by the chemical b and the dust which keep flying, the bag filter is not used. The processing performance of f is
Although it will gradually improve over time during operation, immediately after the dust is removed, the dust layer is removed and the neutralization / filtration capability is lost, resulting in the emission of untreated gas.

In order to prevent this phenomenon, an equivalence ratio of 3-5 is used.
A general measure is to continuously inject a large amount of chemicals to form a dust layer at an early stage. However, if a large amount of chemicals are entrained in the exhaust gas flow, fluctuations in the amount of exhaust gas and a constant supply feeder c ₂
The pulsation of the supply amount of the drug overlaps and the drug mass is easily formed.

In this case, the amount of the drug mass that has entered the hopper chamber f ₄ drops to the discharge device f ₅ more than it rises toward the filtration chamber f _1, and the effective usage rate of the drug b is reduced. Not only will the drug costs rise sharply, but the amount of ash discharged specified as "specially controlled waste" will also increase, resulting in an increase in post-treatment costs.

Therefore, as the amount of the chemical b supplied from the harmful gas removing device c tends to increase,
For almost all of the dust in the exhaust gas d is adsorbed to the filter cloth f ₂ surface, with an excess supply of the drug combination, accelerated the rate of increase in dust layer, reduces the払落a period, a series of払落working In many cases, it is almost continuous.

Therefore, in order to solve these problems,
In addition to directly feeding the chemicals to the hopper chamber (dust-containing gas chamber), a baffle plate is installed in front of the exhaust gas inlet (dust-containing gas inlet) to direct the exhaust gas downward and then upward flow. Filter cloth dust collector (Actual Kaihei 2-17213
No.) ”(hereinafter referred to as“ first application ”) has been proposed.

The outline of the prior application is shown in FIG. 6 below. The same members as those of the bag filter device described above are designated by the same reference numerals, and description thereof will be omitted.

Since a baffle plate m is installed on the front surface of the exhaust gas duct e attached to the side wall of the hopper chamber f ₄ , the exhaust gas n containing the acidic harmful gas and dust which has proceeded straight in the exhaust gas duct e. Is once turned downward, and then rises toward the filter cloth f ₂ .

Since the drug supply port p is arranged in the ascending airflow, the powder and the drug mass of the precoat drug b for which the drug has been fed through the drug transport pipe q are blown up by the ascending airflow and are filtered by the filter cloth f. _{(2) A} precoat layer is formed by adhering to the surface, and when the formation is completed, the supply of the drug b is stopped and a normal filtration operation is started.

Because of the operation of forming the precoat layer before starting this normal filtration operation, it is possible to prevent the excessive supply of the chemical agent b, and as a result of the upward reversal of the exhaust gas n, the mass of the dust contained therein becomes large. The substance has the effect of being separated from the exhaust gas n and falling to the exhaust device f ₅ side.

However, since the exhaust gas n diffuses and rises in the hopper chamber f ₄ , the flow velocity suddenly decreases, not only weakening the entrainment force of the chemical b during precoating but also a phenomenon peculiar to the refuse incinerator. Is also affected by the increase and decrease in the amount of exhaust gas,
It is difficult to evenly distribute the drug b on the surface of the filter cloth f ₂ , and in order to prevent the discharge of the untreated gas due to the saturation of a part of the precoat layer, the problem that the unreacted agent on the other filter cloth is also removed is left. Was there.

[0022]

A precoat type bag filter device provided with a guide vane of the present invention is a precoat type bag filter device in which a precoat layer is previously formed on the surface of a filter cloth before performing a filtering operation. An exhaust gas duct is connected to the hopper chamber below the filtration chamber that suspends the filter cloth,
A guide vane for guiding a gas flow, which is vertically rotatable, is provided at a position facing the exhaust gas introduction port of the exhaust gas duct, and the guide vane guides the exhaust gas and the chemicals introduced from the exhaust gas introduction port upward when the precoat layer is formed. The guide vane is arranged at an upward position, and the upward angle of the guide vane is displaceable, while it is arranged at a downward position for temporarily guiding the exhaust gas downward during a filtering operation.

At the time of forming the precoat layer, the exhaust gas containing the chemical, which has proceeded straight in the exhaust gas duct, reaches the surface of the filter cloth as an upward flow by the upward guide vanes provided facing the exhaust gas inlet. By filtering the chemicals in the exhaust gas, a precoat layer is formed on the surface of the filter cloth. At this time, the upward angle of the guide vane is displaced to guide the drug upward in a uniform distribution state.

When the desired precoat layer is formed, the supply of the drug is stopped and the guide vanes are turned to the downward position, whereby the exhaust gas is once guided downward and then inverted upward at the bottom. To do. At this time, coarse particles of dust contained in the exhaust gas are shaken off to be separated downward and then risen to start a normal filtration operation.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view mainly showing a hopper chamber portion of a precoat type bag filter device having a guide vane according to the present invention, and FIG. 2 is a schematic flow of an exhaust gas treating apparatus including the bag filter device. 3 and 4 are a front view and a side view showing an example of the guide vane.

In FIGS. 1 to 3, 1 is a bag filter device, 11 is a filtration chamber for suspending a plurality of filter cloths 12, and below the filtration chamber 11 is an inverted pyramidal hopper chamber 13 and a dust discharge device. 14 are connected to each other, and a clean gas chamber 16 having a dust removing device 15 is formed above the filtration chamber 11.

On the side wall of the hopper chamber 13, the exhaust gas duct 2
Is connected through the exhaust gas inlet 21, and the exhaust gas 3 generated in a waste incinerator (not shown) and cooled by a gas cooling device (not shown) is sucked into the exhaust gas duct 2 by an attracting fan (not shown). Flows in.

Further, the exhaust gas inlet 2 in the hopper chamber 13
A guide vane 4 is provided at a position opposite to 1. The guide vanes 4 are bottom plates 4 with outer edges 42, 42.
The cross section of 3 is crescent-shaped, and is configured to be vertically rotatable about a shaft 41 by a drive device (not shown). Specifically, the guide vane 4 has an upward position (see a solid line in FIG. 1) that guides the exhaust gas introduced from the exhaust gas inlet 21 upward and a downward position (see a chain line in FIG. 1) that temporarily guides the exhaust gas downward. In addition, the upward angle of the guide vane 4 in the upward position can be displaced during precoating described later.

Reference numeral 5 designates a medicine storage tank 51 and a fixed quantity supply feeder 5.
2, a harmful gas removing device comprising a blower blower 53 and a chemical transport pipe 54, and a precoat chemical 6 stored in the chemical storage tank 51 which is an acidic harmful gas neutralizing agent such as slaked lime 6
Is a chemical supply point 22 provided in the middle of the exhaust gas duct 2.
It is designed to be shipped by air.

The clean gas chamber 16 is connected to the clean gas duct 7 provided with a gas amount control damper 71, and the clean gas 8 filtered by the bag filter device 1 is sucked by an unillustrated draft fan to the outside. It is designed to be released.

The operation of the exhaust gas treatment facility constructed as above will be described.

FIG. 4 is a schematic diagram showing changes in the deposition condition on the surface of the filter cloth 12.

1 to 4, a high temperature combustion gas containing an acidic harmful gas and dust generated in an incinerator (not shown) is cooled by a gas cooling device (not shown) to form an exhaust gas 3 which is also drawn by an attracting fan (not shown). Then, it is sucked into the bag filter device 1 through the exhaust gas duct 2.

In the precoat layer forming operation prior to the filtering operation, the chemicals 6 which are transported in large quantities from the harmful gas removing device 5 at once are blown into the exhaust gas duct 2 from the chemical supply point 22.
The mixed gas 31 mixed with the exhaust gas 3 is introduced into the hopper chamber 13 through the exhaust gas inlet 21.

Here, the guide vanes 4 arranged at the positions facing the exhaust gas inlet 21 are set in the upward position shown by the solid line in FIG. 1, whereby the mixed gas 31 that has proceeded straight in the exhaust gas duct 2 is guided. Guided by the bottom plate 43 of the vane 4, it rises to the upper filtration chamber 11 side at a high speed, reaches the surfaces of the plurality of filter cloths 12, and the solid substances such as the chemicals 6 and dust in the mixed gas 31 are filtered. As a result, the precoat layer 61 composed mainly of the chemical agent 6 is formed on the surface of the filter cloth in a short time.
(Refer to FIG. 4) Although the flow rate of the mixed gas 31 at the time of forming the precoat layer 61 is adjusted by the gas amount control valve 71 shown in FIG. The distribution is not uniform. Therefore, by displacing the upward angle of the guide vanes 4 to disperse the rising direction of the medicine 6 guided to the bottom plate 43, the medicine 6 can be evenly distributed, and the medicines 6 can be spread on the surfaces of the plurality of filter cloths 12. The distribution state of the drug 6 can be made uniform. Needless to say, the upward displacement of the guide vanes 4 is performed within a range that does not hinder the rise of the medicine 6.

When the desired precoat layer 61 is formed, the process proceeds to normal filtration work. At that time, if the chemical supply from the harmful gas removing device 5 is stopped, the mixed gas 31 is recovered. Return to Exhaust Gas 3. Next, guide vanes 4
From the upward position shown by the solid line in FIG. 1 to the downward position shown by the alternate long and short dash line.
Is changed from upflow to downflow.

As a result, the exhaust gas 3 descends to the lower part of the hopper, and then is reversed to the upper filtration chamber 11 side by the suction action from the filtration chamber 11 side. Grain dust 32 is separated by centrifugal force,
The filter cloth 12 is discharged to the dust discharging device 14 side.
It is possible to reduce the burden of filtration and to extend the period of withdrawal due to an increase in differential pressure.

The remaining separated exhaust gas 33 from which the coarse particle dust 32 has been removed rises in an inverted manner and reaches the precoat layer 61 formed on the surface of the filter cloth 12.

Since the precoat layer 61 is composed of a neutralizing agent such as slaked lime as described above, the acidic harmful gas contained in the separated exhaust gas 33 undergoes a neutralization reaction with the chemical 6 and the remaining content is The medium / fine grained dust which is the precoat layer 61
Dust layer 62 (see FIG. 4) that is filtered and deposited on the surface of
As a result, the separated exhaust gas 33 passes through the precoat layer 61 to become the clean gas 8 and is discharged from the clean gas chamber 16 to the outside through the clean gas duct 7.

That is, since the precoat layer 61 having the neutralizing / removing ability is formed from the beginning of the filtering operation,
There is no fear of shortage of capacity immediately after the conventional technology is used.

If the above-mentioned filtration work is continued, the neutralization reaction of the chemical agent 6 in the precoat layer 61 is completed, the incompletely treated acidic harmful gas is discharged, and the ventilation resistance of the dust layer 62 is increased. Don't Do the heavy load on the draft fan.

In this case, the controller 9 requests the removal request by detecting a decrease in the neutralization processing capacity by the exhaust gas concentration meter 91 shown in FIG. 2 or an increase in the dust accumulation amount by the differential pressure detector 92.
Send to Then, in response to a command from the control device 9, the jet pulse from the compressed air source (not shown) is removed by the dust removing device 1.
5, the precoat layer 61 and the dust layer 62 attached to the surface of the filter cloth 12 are peeled off and discharged from the hopper chamber 13 to the outside through the dust discharging device 14.

The discharged ash is composed only of the almost reacted chemical agent 6, the collected dust and the separated coarse particle dust, and does not contain the unreacted chemical agent due to excessive supply, so the amount thereof is small. The post-processing cost can be reduced.

Here, the functions of the control device 9 are summarized as follows.
In addition to the above-mentioned wiping operation, it is also used for operating the auxiliary equipment in addition to the position control of the guide vanes 4, the gas amount control, and the drug amount adjustment.

In this example, the bag filter device 1 is
Although the description has been given for the single-chamber structure, it is a multi-chamber type in which a plurality of unit dust collecting mechanisms having the same structure as this description are assembled, and the number of operating units of the unit dust collecting mechanism is selected so that the processing per one unit A method of keeping the gas amount near the rated value may be adopted.

The shape of the guide vane 4 is shown in FIG. 3 as an example, but the shape is not limited as long as the function of the present invention is satisfied.

[0048]

As described above, according to the present invention, the guide vanes for guiding the gas flow which are vertically rotatable are provided at the opposite positions of the exhaust gas duct connected to the hopper chamber, and at the time of precoating, This is a method of displacing the upward angle of the guide vanes.

Therefore, at the time of forming the precoat layer, the chemical agent and the exhaust gas are guided upward with the guide vane facing upward, and the upward angle of the guide vane is displaced to form the precoat layer evenly on the surfaces of the plurality of filter cloths. Then, since the filtration operation is started, there is no decrease in efficiency immediately after the removal as in the conventional method, and the drug cost rises due to the excessive supply of the drug and the exhaust ash post-treatment cost increases. There is no fear. In addition, it is possible to prevent early removal due to uneven formation of the precoat layer on each filter cloth surface.

Further, in a normal filtration operation, the guide vanes are turned to the downward position to guide the exhaust gas downward, and thereafter, the exhaust gas is inverted upward at the bottom of the hopper chamber. The capacity can be increased and the pay-off period can be extended.

[Brief description of drawings]

FIG. 1 is a cross-sectional view mainly showing a hopper chamber portion of a precoat type bag filter device provided with a guide vane according to the present invention.

FIG. 2 is a schematic flow diagram of an exhaust gas treatment apparatus including a precoat type bag filter device.

FIG. 3A is a front view showing an example of a guide vane,
(B) is a side view.

FIG. 4 is an enlarged cross-sectional view showing an adhered / deposited state on the surface of the filter cloth.

FIG. 5 is a diagram showing an outline of a conventional bag filter device.

FIG. 6 is a diagram schematically showing a conventional bag filter device in which a baffle plate is provided at an exhaust gas inlet.

[Explanation of symbols]

 1 Bag Filter Device 11 Filtration Chamber 12 Filter Cloth 13 Hopper Chamber 2 Exhaust Gas Duct 21 Exhaust Gas Inlet 3 Exhaust Gas 4 Guide Vane 6 Chemicals 61 Precoat Layer

Claims (1)

[Claims] 1. In a pre-coating bag filter device in which a pre-coat layer is formed on the surface of a filter cloth in advance before performing a filtering operation, an exhaust gas duct is connected to a hopper chamber below a filter chamber for suspending a plurality of filter cloths. A guide vane for guiding a gas flow, which is vertically rotatable, is provided at a position facing the exhaust gas introduction port of the exhaust gas duct, and the guide vane guides the exhaust gas and the chemicals introduced from the exhaust gas introduction port upward when the precoat layer is formed. The guide vane is arranged at an upward position, and the upward angle of the guide vane is displaceable, while it is arranged at a downward position for temporarily guiding the exhaust gas downward during filtration work. Pre-coated bag filter device with guide vanes.