JP3337533B2 - Exhaust gas treatment method using filtration type dust collector - Google Patents

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 method using a filtration type dust collector, and more particularly to a method for stably removing harmful acidic components such as hydrogen chloride contained in combustion exhaust gas discharged from a refuse incinerator or the like. Moreover, the present invention relates to an exhaust gas treatment method using a filtration type dust collector which can be efficiently removed.

[0002]

2. Description of the Related Art Combustion exhaust gas discharged from a refuse incinerator for incinerating waste such as municipal waste and sludge is cooled, for example, by a cooler or an air preheater and then cooled by an electric precipitator (E).
P) or the dust was removed by a filtration dust collector. However, after organic chlorine compounds such as dioxin are detected from the exhaust gas of a refuse incinerator for incinerating miscellaneous waste, a method using a filtration type dust collector is mainly used.

FIG. 3 is a diagram showing a system of an exhaust gas treatment device of a refuse incinerator using a bag filter as a filtration type dust collector. This device mainly includes a gas cooler 22, an air preheater 23, and a bag filter 24 which are sequentially arranged in an exhaust gas flue 27 of an incinerator 21, and an induction blower 25 and a chimney 26 downstream of the bag filter 24. Have been. The combustion exhaust gas generated in the incinerator 21 is supplied to the gas cooler 2
After being cooled to a predetermined temperature by the air preheater 2 and the air preheater 23, a neutralizing agent that reacts with an acidic component contained in the exhaust gas, for example, a desalinating agent is added, and then flows into the bag filter 24, and the acid in the exhaust gas The components are collected together with other solids as a reaction product reacted with the neutralizing agent. The exhaust gas from which the acidic components and the solid content have been removed is discharged to the atmosphere from a stack 26 downstream of the exhaust gas as a processing gas.

In the conventional exhaust gas treatment method using the above-mentioned filtration type dust collector, the influence of pressure fluctuation in the exhaust gas flue is caused by the continuous addition of a neutralizing agent (hereinafter referred to as a desalting agent or simply as a chemical). As a result, the transport air flows back to the supply side, which hinders stable supply of the desalinating agent and causes inconveniences such as leakage from the shaft seal. Was. The amount of desalting agent continuously supplied is
Since the amount is very small compared to the total amount of exhaust gas, it is difficult to accurately measure the amount of addition, and there is a disadvantage that the amount of addition is more than necessary.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to carry out a stable desalination operation without being affected by pressure fluctuations at a desalinating agent supply destination. An object of the present invention is to provide an exhaust gas treatment method using a filtration type dust collector capable of accurately measuring a supply amount of a salt agent.

[0006]

In order to achieve the above object, the present invention provides a method for spraying a neutralizing agent onto an exhaust gas flue by using a carrier medium and reacting the neutralizing agent with acidic components in the exhaust gas. the in the exhaust gas processing method for trapping by filtration type dust collector, characterized in that while intermittently supplying the neutralizer, shake off collecting dust of the filtration type dust collector according to the spray conditions of the neutralizing agent And

[0007] By neutralizing acidic components in the exhaust gas, for example, by intermittently supplying a desalting agent, it is possible to separate the drug extracting device and the transport pipe by, for example, a valve.
As a result, the medicine can be sprayed at a high pressure, which is not affected by the pressure fluctuation of the exhaust gas flue, and a stable supply of the desalting agent becomes possible, and the desalting operation is stabilized. Further, even if the desalinating agent is a very small amount compared to the total exhaust gas amount, it can be measured by intermittently supplying the desalinating agent, so that the required amount can be accurately added. Further, the operation of removing the collected dust of the filtration type dust collector and the operation of spraying the desalinating agent were linked, for example, by performing the operation of removing the collected dust when the spraying of the desalinating agent was stopped, the spraying was performed. Since the disadvantage that the desalting agent is discharged out of the system without contributing to the neutralization reaction can be avoided, the desalting agent can be effectively used.

In the present invention, the operation of removing the collected dust from the filtration type dust collector is performed according to the spraying state of the neutralizing agent. In other words, for example, when the spraying of the neutralizing agent is stopped, dust can be removed from the dust collector,
For example, when the exhaust gas regulation value is low, the neutralizing agent spraying operation is performed repeatedly even when dust is removed, so that a reduction in the removal rate can be prevented. When a harmful gas analyzer is installed, for example, not only the amount of the neutralizing agent but also a feedback control including a change in the supply pattern can be performed based on the measured value.

In the present invention, a desalination reaction as a neutralization reaction in a filter type dust collector occurs when an acidic component in exhaust gas passes through a layer of a desalting agent and dust formed on the surface of a filter cloth. The capture rate of the acidic component is not affected in a short time by a change in the supply amount of the desalting agent.
Therefore, even if the desalting agent is intermittently supplied, the desalting rate does not decrease.

In the present invention, slaked lime (Ca (OH) ₂ ), quicklime (CaO), limestone (CaCO ₃ ) and the like are preferably used as the desalting agent. Further, it is preferable to use a desalting agent and a desalting aid in combination. As the desalting aid, for example, diatomaceous earth is used. It is preferable that the desalting agent and the desalting aid be a powder having a particle size that allows the air to be conveyed into an exhaust gas flue.

[0011]

Next, the present invention will be described in more detail with reference to examples. FIG. 1 is an apparatus system diagram showing one embodiment of the present invention. This device includes, for example, an exhaust gas treatment device having a bag filter 12 provided in an exhaust gas flue 11 through which exhaust gas 13 from a refuse incinerator flows, and an exhaust gas flue upstream of the bag filter 12 of the exhaust gas treatment device. It is roughly divided into a desalinating agent supply device that supplies a salting agent. A desalinating agent supply device includes a desalinating agent tank 1 and a desalinating agent supply device 2 provided at the bottom of the desalinating agent tank 1, and a desalinating agent tank 3 and a bottom of the desalinating agent tank 3. An auxiliary feeder 4 provided; a collecting pipe 5 where the desalinating agent cut out by the desalinating agent feeder 2 and the auxiliary feeding machine 4 and the desalting auxiliary join together; A measuring tank 7 provided in the flow, an inlet valve 6 provided between the collecting pipe 5 and the measuring tank 7, an outlet valve 8 provided at an outlet of the measuring tank 7, It is mainly constituted by a blower 9 for sending conveying air for conveying the discharged desalinating agent and the like to the exhaust gas flue 11 of the exhaust gas treatment device via the transport pipe 14 and the three-way valve 10. The outlet pipe of the blower 9 is connected to a branch pipe 15 for supplying a part of the conveying air to the bottom of the measuring tank 7.
Reference numeral 16 denotes a control device for controlling the number of rotations of the desalinating agent supply device 2 and the auxiliary agent supply device 4, the opening of the measuring tank inlet valve 7, the outlet valve 8 and the three-way valve 10, and the like.

In such a configuration, the exhaust gas flue 11
The supply of the desalinating agent is performed as follows. That is, first, the desalinating agent feeder 2 is operated in a state where the inlet valve 6 of the measuring tank 7 is opened and the outlet valve 8 is closed, and the desalinating agent in the desalinating tank 1 is cut out and the measuring tank 7 is cut out. Flows into. The desalinating agent flowing into the measuring tank 7 is continuously measured, and when the set value is reached, the operation of the desalinating agent feeder 2 is stopped.
Next, if necessary, the desalting aid supply device 4 is operated, and the desalting aid in the desalting aid tank 3 is similarly introduced into the measuring tank 7 through the collecting pipe 5. At this time, the desalting aid is continuously measured in the same manner as the desalting agent. After the required amount of the desalinating agent and the desalinating aid is filled in the measuring tank 7 in this way, the inlet valve 6 is closed and the outlet valve 8 is opened to open the desalinating agent and the desalinating agent in the measuring tank 7. The auxiliary agent (hereinafter, simply referred to as a desalting agent) is discharged by the carrier air blown from the blower 9. At this time, the discharge of the desalinating agent is smoothly performed by a part of the transport air supplied from the branch pipe 15.
The desalinating agent discharged from the measuring tank 7 in this way is supplied to the exhaust gas flue 11 of the exhaust gas treatment device via the transport pipe 14 and the three-way valve 10 by the carrier air. Selection of the desalinating agent supply destination is performed by switching the three-way valve 10, and in the figure, the desalting agent can be supplied to the other two lines outside the exhaust gas treatment device. In addition, the desalinating agent is supplied after the operation of removing the collected dust is started so as not to overlap with the operation of removing the collected dust of the bag filter 12 of the exhaust gas treatment device. It is supplied intermittently so as not to overlap.

The desalinating agent sprayed on the exhaust gas flue 11 in this manner is deposited on the surface of the filter cloth of the bag filter 12 downstream to form a desalinating agent layer, and flows through the desalinating agent layer. The acidic component in the exhaust gas is fixed as a neutralization reaction product. The solid matter in the exhaust gas is also separated by the bag filter, and the exhaust gas from which the acidic components and the solid components have been removed is emitted to the atmosphere as a processing gas, for example, from a downstream stack (not shown).

According to this embodiment, by intermittently supplying the desalinating agent, it is possible to separate the desalting agent extracting device from the transport pipe by the valve, and as a result, there is no influence from the flue pressure fluctuation. The desalting agent can be stably supplied at a high pressure. Therefore, the desalting process in the bag filter 12 is also stabilized. In addition, even when a very small amount of a desalinating agent is added as compared with the total amount of exhaust gas, it can be supplied collectively by intermittent supply, so that the supply amount can be accurately measured. Further, since the desalting agent is not supplied when the collected dust is removed by the bag filter, there is no desalting agent discharged to the outside of the system without contributing to the desalination reaction, and the desalinating agent can be effectively used. .

According to this embodiment, by supplying the desalinating agent intermittently, the desalinating agent can be supplied to a plurality of exhaust gas treatment devices using a single series of desalinating agent supply devices. In this embodiment, compressed air may be separately used instead of the transport air supplied from the branch pipe 15 to the bottom of the measuring tank 7. Further, in place of the conveying air, for example, exhaust gas after treatment can be used.

FIG. 2 shows a desalinating agent supplying operation and a bag filter dusting-off operation (pulse operation) when supplying a desalinating agent to a three-line exhaust gas treatment apparatus using one series of desalinating agent supplying apparatuses. FIG. 7 is an operation procedure explanatory diagram showing the relationship with ()). In the figure, the desalinating agent is supplied to the first system exhaust gas treatment device after the collected dust is discharged, and then the intermittent supply of the desalinating agent and the exhaust gas treatment are performed. The desalinating agent is supplied for a certain period of time to the exhaust gas treatment device of the second system from which the desalinating agent is supplied to the first system so as not to overlap with the operation of supplying the desalinating agent to the first system. The exhaust gas treatment device of the third system, which has been operated for removing the collected dust for a certain period of time, is degassed for a certain period of time so as not to overlap with the desalting agent supply operation to the first and second systems. After the salt is supplied, intermittent supply of the desalin and exhaust gas treatment are performed. By performing the intermittent supply of the desalting agent in this manner, a plurality of exhaust gas treatments can be performed by one system of the desalinating agent supply device, that is, one desalinating agent supply device, a desalting auxiliary agent supplying device, a blower, a transport pipe, and the like. The desalinating agent can be supplied to the device, and the desalinating agent supply device can be effectively used.

In this embodiment, the explanation has been made mainly on the desalination operation of the exhaust gas. However, the present invention can be similarly applied to other exhaust gas treatments such as a desulfurization operation.

[0018]

According to the present invention, in a flue gas treatment apparatus using a filtration type dust collector, a desalinating agent for neutralizing acidic components in the flue gas is intermittently supplied, and a filtration type is used according to the supply condition. By performing the collecting dust removing operation of the dust collector, a required amount of the desalinating agent can be stably supplied to perform a stable desalting treatment, and the desalinating agent can be effectively used. In addition, the desalinating agent can be supplied to a plurality of exhaust gas treatment devices with a single system of desalinating device without complicating the device.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is an operation procedure explanatory diagram showing one embodiment of the present invention.

FIG. 3 is an explanatory view showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... desalinating agent tank, 2 ... desalinating agent supply machine, 3 ... desalinating auxiliary tank, 4 ... auxiliary agent supplying machine, 5 ... collecting pipe, 6 ... inlet valve,
7: measuring tank, 8: outlet valve, 9: blower, 10: three-way valve, 11: exhaust gas flue, 12: bag filter, 13
... exhaust gas, 14 ... transport pipe, 15 ... branch pipe, 16 ... control device.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 53/34 ZAB B01D 53/34 118

Claims (1)

(57) [Claims] An exhaust gas treatment method comprising spraying a neutralizing agent onto an exhaust gas flue using a carrier medium to react with an acidic component in the exhaust gas, and then collecting a reaction product by a filtration dust collector. wherein the neutralizing agent as well as intermittent supply, exhaust gas treatment method using a filtration type dust collector which corresponds to the spraying conditions of the neutralizing agent, characterized in that shake off collecting dust of the filtration type precipitator.