JP2007260607A - Treating method of waste gas and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide equipment for preventing the deposition of dust on the surface or in the inside of a catalyst layer in a catalyst reaction column in waste gas treating equipment such as an incinerator and eliminating the need of stopping the operation of waste gas treatment and cleaning the catalyst layer due to decline of waste gas treating ability due to increase of pressure loss. <P>SOLUTION: A filter 2 for removing the dust is provided on the upstream side of the catalyst reaction column 1. The filter 2 sucks and removes the dust by a dust suction hood 6 provided on the upper part of the filter 2 while being transferred in one direction or back and forth directions. Moreover, a blow-off header 8 is provided on the lower part of the filter 2, clogging of the filter 2 is prevented and the dust is surely removed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and apparatus for treating exhaust gas generated from an incinerator or the like.

  One of the means for removing dioxins, nitrogen oxides and the like contained in exhaust gas from an incinerator is a method using a dry catalyst layer.

  Usually, the catalyst layer has a spherical, cylindrical, rod or honeycomb shape composed of components such as titanium-vanadium, and the shape is required for the pressure loss allowed in the treatment process, the cleanliness of the exhaust gas, and the like. The shape is selected considering the removal efficiency.

  Of these, the honeycomb-shaped catalyst layer is often applied in the case of exhaust gas with relatively little dust, such as a dust collector installed upstream.

However, when the dust collector is a dry electrostatic precipitator, when garbage containing a large amount of carbon fiber is burned in an incinerator, the carbon-based long fiber dust is not charged in the dry electrostatic precipitator and is not removed by the dry dust collector. The catalyst is transported to the catalyst layer and is deposited on the surface or inside of the catalyst layer. As a result, an extreme pressure loss may be generated and the exhaust gas treatment capacity may be lowered.
In such a situation, it becomes necessary to stop the operation and clean the catalyst layer.

  Conventionally, Patent Document 1 is known as a prior art for preventing a reduction in exhaust gas treatment capacity due to dust accumulation in a catalyst layer. In Patent Document 1, flue gas discharged from a boiler is introduced into a denitration device through a cyclone filter and an electrostatic precipitator, and NOx is decomposed by a catalyst layer provided in the device. Prepare dust with lower bulkiness than intruding dust, and when normal dust accumulates on the catalyst layer and the pressure loss exceeds the specified value, dust with lower bulkiness is thrown into the catalyst layer A method is disclosed.

  However, according to the technique disclosed in Patent Document 1, since it is a method of reducing pressure loss by mixing other dust into dust causing pressure loss, not all of them can be applied to catalyst layers having various shapes. There is no problem.

JP-A-53-95871

  The present invention prevents the accumulation of dust on the surface or inside of the catalyst layer in the catalytic reaction tower in the exhaust gas treatment facility, and stops the operation of the exhaust gas treatment due to the decrease in the exhaust gas treatment capacity due to the increase in pressure loss and the cleaning of the catalyst layer. The purpose is to provide unnecessary equipment.

  The first invention is a method for treating exhaust gas, characterized in that dust accumulation on the surface and inside of the catalyst layer is prevented by a filter provided upstream of the catalytic reaction tower.

  A second invention is an exhaust gas treatment apparatus comprising a catalytic reaction tower, a filter upstream of the catalytic reaction tower, and a suction device for sucking dust accumulated on the filter.

  A third invention is the exhaust gas treatment apparatus according to the second invention, characterized in that the endless drive mechanism moves the filter in one direction or in a reciprocating direction.

  A fourth invention is the exhaust gas treatment apparatus according to the second invention or the third invention, characterized in that a blow-out header for blowing gas from below the filter is provided.

  The exhaust gas treatment method and apparatus of the present invention can remove dust adhering to the catalyst in advance by installing a filter upstream of the catalytic reaction tower. As a result, operation for regular and irregular cleaning is possible. The operating rate is improved because there is no stopping.

  Further, since dust adhering to the filter is sucked and removed by the suction device, dust collection can be automated.

  Furthermore, since the filter is an endless drive mechanism, the adhering dust can be removed continuously, so that the operation stop for cleaning the filter is reduced.

  In addition, the filter can be prevented from being clogged by a gas blowing header provided below the filter.

  In the present invention, a filter is installed upstream of the catalytic reaction tower. The material of the filter is a fiber type, a polymer type such as plastic, or a metal type, and is selected depending on the temperature, component, flow rate, etc. of the exhaust gas. Normally, since the exhaust gas temperature is controlled at about 200 ° C. to 350 ° C. in order to enhance the dust collection effect of the electrostatic precipitator, it is preferable to use a stainless steel filter (SUS304, SUS316, etc.) under such high temperature conditions.

  A dust suction device for always sucking is provided on the surface of the filter. Moreover, there are a method of periodically replacing the filter by one-way winding and a method of using it for a certain period of time by reciprocating winding.

  Further, the filter may be an endless type and may be wound in one direction or in a reciprocating direction.

FIG. 1 is a side view of an embodiment of the apparatus of the present invention.
In FIG. 1, 1 is a catalytic reaction tower, 2 is a filter, and is installed upstream of the catalytic reaction tower 1. The filter 2 is suspended in an endless state between a drive wheel 4 and a driven wheel 5 directly connected to the drive source 3, and is formed of a stainless steel filter as an example.
6 is a dust suction hood which continuously sucks in dust 7 on the filter 2 being transferred. Reference numeral 8 denotes a blowout header for cleaning the filter 2. 9 is an auxiliary suction header.

  The dust suction hood 6 is connected to a dust collector 10 via a suction pipe 11, and the dust 7 on the filter 2 is transferred into the dust collector 10 by the suction force of the dust collecting blower 12.

  The cleaning blowing header 8 is connected to a pipe 13, and the pipe 13 is provided with switching valves 14 and 15 below. Between the switching valves 14 and 15, a pipe 17 connected to a reverse blowing blower 16 that also serves as dust transport is connected. Therefore, when the air is blown upward from the lower side of the filter 2, the switching valve 14 is opened, the switching valve 15 is closed, and the air from the reverse blower 16 is supplied to the cleaning blower header 8. The suction of the suction hood 6 of the upper dust 7 is promoted, and the filter 2 is prevented from being clogged.

  Also, the reverse blower 16 sends air to the fly ash feeder 19 provided at the lower part of the dust collector 10 via the pipe 18 by closing the switching valve 14 and opening the switching valve 15, and the inside of the dust collector 10. The fly ash collected below is sent to the fly ash storage hopper 21 through the pipe 20.

  In addition, 22 is exhaust gas from a waste incinerator, 23 is an electric dust collector, 24 is a duct for supplying the exhaust gas 22 to the catalytic reaction tower 1, 25 is a screen plate, 26, 27 and 28 are in the catalytic reaction tower 1. Are a plurality of catalyst layers.

  A main blower 29 attracts the exhaust gas 22 in the catalytic reaction tower 1, and the treated clean gas is released from the chimney 30 into the atmosphere.

  The present invention can be applied not only to an exhaust gas treatment facility of an incinerator but also to a general exhaust gas treatment facility such as a heating furnace having a dry catalyst, a sintering furnace, or a coke oven.

It is a side view explaining one Example of the processing method and apparatus of the waste gas of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Catalytic reaction tower 2 Filter 3 Drive source 4 Drive wheel 5 Driven wheel 6 Dust suction hood 7 Dust 8 Blow header 9 Auxiliary suction header 10 Dust collector 11 Suction pipe 12 Dust collection blower 13 Pipe 14 Switch valve 15 Switch valve 16 Reverse blow blower 17 pipe 18 pipe 19 fly ash feeder 20 pipe 21 fly ash storage hopper 22 exhaust gas 23 electrostatic precipitator 24 duct 25 screen plate 26 catalyst layer 27 catalyst layer 28 catalyst layer 29 main blower 30 chimney

Claims (4)

  A method for treating exhaust gas, characterized in that dust accumulation on the surface and inside of the catalyst layer is prevented by a filter provided on the upstream side of the catalyst reaction tower.   An exhaust gas treatment apparatus comprising: a catalytic reaction tower; a filter upstream of the catalytic reaction tower; and a suction device for sucking dust accumulated on the filter.   The exhaust gas treatment apparatus according to claim 2, wherein the endless drive mechanism moves the filter in one direction or in a reciprocating direction. The exhaust gas treatment apparatus according to claim 2 or 3, wherein a blow-out header for blowing gas from below the filter is provided.

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