JPH10238741A - Catalytic combustion type thermal storage exhaust gas treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend a catalytic life by reducing poisoning of catalyst even when untreated exhaust gas contains substance to become catalytic poison. SOLUTION: A plurality of thermal storage chambers 5A to 5C each having a thermal storage layer 4 are provided in parallel with an exhaust gas heating chamber 3. Catalytic layer 7A to 7C for oxidation burning or thermally decomposing to purify combustible component contained in untreated exhaust gas are formed between the layers and the chamber 3. And, catalytic poison adsorption filters 20, 21 for absorbing the poison contained in the gas are replaceably mounted at any one or both of the sides of the chambers 5A to 5C and the chamber 3. The filters 20, 21 are formed by coating carriers with active alumina, or carrying alkali metal or alkali each metal to the carriers coated with the alumina.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a purifying treatment by converting flammable harmful components and flammable odor components contained in exhaust gas into harmless and odorless substances by oxidizing and burning or thermally decomposing them in the presence of a catalyst. The present invention relates to a catalytic combustion type heat storage exhaust gas treatment apparatus for recovering and reusing heat generated at that time.

[0002]

2. Description of the Related Art In various facilities such as a coating booth, a coating drying oven, a printing drying oven, a plastic or plywood manufacturing facility, a food processing facility, an industrial waste treatment facility, or a fragrance manufacturing facility, paint, ink, and solvent are used. Combustible harmful odor components such as alcohols, esters, phenols and aldehydes having harmful and peculiar odors are generated from adhesives, adhesives, synthetic resins or chemicals.

[0003] Since exhaust gas containing such harmful odor components cannot be directly released into the atmosphere from the viewpoint of pollution prevention, it is usually subjected to a purification treatment and released in a harmless and odorless state. . As a typical purification treatment method, there is known a direct combustion method in which harmful odor components in exhaust gas are oxidized and burned or thermally decomposed at a high temperature of 700 to 900 ° C. to change into carbon dioxide and water to make them harmless and odorless. I have. This has the advantage that the purification effect is not inferior to other treatment methods and that it can be applied to combustible odorous odor components in general, but on the other hand, fuel consumption is large. However, there is a disadvantage that running cost is increased due to increased fuel efficiency.

[0004] Therefore, in order to suppress fuel consumption and reduce running costs, there has been proposed a catalytic combustion method in which flammable harmful odor components contained in exhaust gas are oxidized and burned or thermally decomposed in the presence of a catalyst. This is a method in which oxidizing combustion or thermal decomposition reaction proceeds in the presence of a platinum-based, cobalt-based, nickel-based catalyst, etc. to decompose combustible harmful odorous components into carbon dioxide gas and water to make them harmless and odorless. Since the purification treatment can be performed at a low temperature of about 300 to 450 ° C. as compared with the direct combustion method, there is an advantage that running costs can be reduced. Further, recently, a catalytic combustion type thermal storage exhaust gas treatment apparatus has been proposed in which the running cost is further reduced by effectively utilizing the heat of high-temperature treated exhaust gas purified by oxidative combustion or thermal decomposition in the presence of a catalyst. (See JP-A-5-66005).

FIG. 2 shows an exhaust gas treatment apparatus 1 of this type, in which a plurality of heat storage chambers 5 A are provided for an exhaust gas heating chamber 3 provided with a heating device 2 such as a gas burner for heating untreated exhaust gas to a predetermined temperature. To 5C, and the heat storage chamber 5
A to 5C are provided with a heat storage layer 4 for recovering heat when discharging the high-temperature treated exhaust gas and preheating the exhaust gas with the previously recovered heat when introducing the low-temperature untreated exhaust gas. ing. The exhaust gas heating chamber 3 and each heat storage chamber 5A
Pt-based and cobalt-based materials that oxidize, burn, or thermally decompose flammable harmful odor components in the exhaust gas heated in the exhaust gas heating chamber 3 to convert them into harmless and odorless materials. And catalyst layers 7A to 7C formed of a nickel-based catalyst or the like. Each of the heat storage chambers 5A-
5C, untreated exhaust gas introduction ducts 8A to 8C for introducing untreated exhaust gas into the exhaust gas heating chamber 3 on the opposite side of the exhaust gas heating chamber 3 across the heat storage layer 4, and a catalyst layer 7A heated in the exhaust gas heating chamber 3 Exhaust gas exhaust ducts 9A to 9C for exhausting the purified exhaust gas that has been purified by passing through the exhaust gases 9A to 9C
And purge ducts 10A to 10C for discharging untreated exhaust gas remaining in each of the heat storage chambers 5A to 5C with a small amount of heated exhaust gas introduced from the exhaust gas heating chamber 3 and returning the exhaust gas to the heat storage chambers 5A to 5C on the introduction side. ing.

[0006] Each of the ducts 8A to 8C, 9A
~ 9C, 10A ~ 10C have auto dampers 11A ~ 1
1C, 12A to 12C, and 13A to 13C are interposed, and these are turned on / off at a predetermined timing to alternately switch the introduction side and the discharge side of the exhaust gas. Thereby, after the untreated exhaust gas introduced from one of the heat storage chambers 5A to 5C is heated in the exhaust gas heating chamber 3, the purification treatment is performed through the catalyst layers 7A to 7C, and the treated exhaust gas is converted into the other heat storage chambers 5A to 5C. The exhaust gas is discharged from 5C, and the purification side is continuously performed by alternately switching the introduction side and the exhaust side of the exhaust gas.

Specifically, first, the auto damper 11
A, 12B and 13C are opened, and the other auto dampers are closed. In this case, the untreated exhaust gas is introduced into the exhaust gas heating chamber 3 through the heat storage chamber 5A on the introduction side, is heated to a predetermined processing temperature (for example, 300 to 450 ° C.), and is purified when passing through the catalyst layer 7B. It is processed. Then, after collecting the heat of the high-temperature treated exhaust gas in the heat storage layer 4 of the heat storage chamber 5B,
The treated exhaust gas is discharged from the discharge duct 9B to the outside. At this time, a part of the high-temperature exhaust gas heated in the exhaust gas heating chamber 3 pushes out and purifies the untreated exhaust gas remaining in the heat storage chamber 5C, and the untreated exhaust gas passes through the purge duct 10C to the introduction-side heat storage chamber 5A. It is refluxed.

Then, for example, when 60 seconds have elapsed,
The automatic dampers 11B, 12C and 13A are opened, and the other automatic dampers are closed. In this case, the untreated exhaust gas is introduced from the heat storage chamber 5B where the heat storage has been completed, the treated exhaust gas is discharged from the heat storage chamber 5C where the purging has been completed, and the heat storage chamber 5A in which the unprocessed gas remains remains purged. When a further 60 seconds have elapsed, the automatic dampers 11C, 12A,
13B is opened, and the other auto dampers are closed. In this case, the untreated exhaust gas is introduced from the heat storage chamber 5C, discharged to the outside of the treated exhaust gas from the heat storage chamber 5A, and the heat storage chamber 5B is purged.

Then, when another 60 seconds have passed,
The automatic dampers 11A, 12B, and 13C are opened again, the other automatic dampers are closed, and this is repeated, whereby the exhaust gas purifying process is continuously performed by alternately switching the exhaust gas introduction side and the exhaust side.

[0010]

By the way, when such a catalytic combustion type heat storage exhaust gas treatment apparatus is used as an exhaust gas treatment apparatus for a coating and drying furnace, the catalyst layers 7A to 7C having a life of 2 to 3 years conventionally. Has a problem in that the service life is shortened, and depending on exhaust gas conditions, it is significantly shortened to several months.
In particular, since this type of catalyst often uses an expensive catalyst in which platinum having excellent catalytic performance is supported on a honeycomb-shaped catalyst carrier coated with activated alumina, if the catalyst life is shortened, replacement of the catalyst is required. Costs increase. When the present inventors investigated the cause, the silica component contained in the siloxane and the like mixed in the paint as a measure for hardening the coating film and acid rain was evaporated, and in particular, a large amount of the siloxane was contained. When applying the paint, a large amount of silica was discharged, and it was found that the activity of the catalyst was lost because the silica component acted as a catalyst poison and formed an inorganic film on the surface of the catalyst. Not only silica but also halogens such as chlorine, lead,
When a catalyst poison such as zinc, arsenic, mercury, phosphorus, and sulfur is contained, the catalyst is similarly poisoned and has a problem of shortening its life.

[0011] Therefore, the present invention is applicable to a case where the untreated exhaust gas contains such a catalyst poisonous substance.
The technical task is to reduce catalyst poisoning and extend the life of the catalyst.

[0012]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention recovers heat when discharging a high-temperature treated exhaust gas, and removes the heat when introducing a low-temperature untreated exhaust gas. A plurality of heat storage chambers having a heat storage layer for preheating are arranged in parallel with an exhaust gas heating chamber provided with a heating device for heating the untreated exhaust gas to a predetermined temperature, and there is no unheated gas between the exhaust gas heating chamber and each heat storage layer. A catalyst layer for purifying by oxidizing, burning or thermally decomposing combustible components contained in the treated exhaust gas is formed, and the untreated exhaust gas introduced from one heat storage chamber is purified by the exhaust gas heating chamber and the catalyst layer. After the treatment, the treated exhaust gas is discharged from other heat storage chambers, and the exhaust gas is contained in the exhaust gas in a catalytic combustion type heat storage exhaust gas treatment device that continuously switches the exhaust gas introduction side and discharge side sequentially and continuously performs the treatment. Catalyst Catalyst poisons adsorption filter for adsorbing found
Attached to one or both of the heat storage chamber side and the exhaust gas heating chamber side of each of the catalyst layers, and the catalyst poison adsorption filter is formed by coating the carrier with activated alumina, or It is characterized by being formed by supporting an alkali metal or an alkaline earth metal on a coated carrier.

According to the present invention, when the catalyst poison adsorption filter is provided on the heat storage chamber side of the catalyst layer, untreated exhaust gas introduced from the heat storage chamber passes through the heat storage layer to a predetermined temperature. It is preheated and passes through the catalyst poison adsorption filter to reach the catalyst layer. Therefore, the catalyst poison which reaches the adsorption temperature when it is preheated to a predetermined temperature through the heat storage layer is efficiently adsorbed. When a catalyst poison adsorption filter is provided on the exhaust gas heating chamber side of the catalyst layer, the untreated exhaust gas heated to a high temperature in the exhaust gas heating chamber passes through the catalyst poison adsorption filter and reaches the catalyst layer. Therefore, a substance that has been heated to a high temperature and changed to a substance that becomes a catalyst poison or a catalyst poison that is easily adsorbed at that temperature is captured by the catalyst poison adsorption filter.

Since the catalyst poison adsorption filter is formed by coating the carrier with activated alumina such as γ-alumina, the surface area thereof is extremely large, and the efficiency of adsorbing the catalyst poison is extremely high. Activated alumina has both amphoteric properties, indicating alkalinity for acidic substances and acidity for basic (alkaline) substances. Therefore, it neutralizes catalyst poisons of any properties. To adsorb. Therefore, regardless of whether the exhaust gas contains acidic or alkaline catalyst poisons, these can be efficiently adsorbed to prevent catalyst poisoning and extend the catalyst life.

Further, as a catalyst poison adsorption filter, if an alkali metal or an alkaline earth metal is supported on a carrier coated with activated alumina, the alkali metal or alkaline earth metal is neutralized to some extent by the activated alumina. Even if the consideration is taken, the surface of the catalyst poison adsorption filter shows strong alkalinity. Therefore, even when a large amount of strongly acidic silica is contained in the exhaust gas, the silica is adsorbed by the alkaline catalyst poison adsorption filter and neutralized, and the catalyst poisoning by silica is more effectively performed. Can be effectively reduced.

As described above, before the exhaust gas passes through the catalyst layer, the catalyst poison contained in the exhaust gas is adsorbed by the catalyst poison adsorption filter disposed on the heat storage chamber side or the exhaust gas heating chamber side. Therefore, the poisoning of the catalyst layer is reduced correspondingly, and the life of the catalyst layer is prolonged. Also, since the catalyst poison adsorption filter does not use expensive noble metals such as platinum, it is cheaper than the catalyst layer, and therefore, even if this is frequently replaced,
The cost is reduced as compared with the case where the catalyst layer is replaced.

[0017]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a catalytic combustion type heat storage exhaust gas treatment apparatus according to the present invention. 2 are given the same reference numerals and the detailed description is omitted.

[0018] Catalytic combustion type heat storage exhaust gas treatment apparatus 1 of the present embodiment
The catalyst poison adsorption filters 20 and 21 for adsorbing catalyst poisons contained in the exhaust gas are exchangeably mounted on the heat storage chambers 5A to 5C side or the exhaust gas heating chamber 3 side of each of the catalyst layers 7A to 7C. The catalyst layers 7A to 7C are formed by, for example, a pellet-type or saddle-type catalyst carrier made of activated alumina, silica, or the like, on which a noble metal such as platinum, palladium alloy, cobalt, or nickel as a catalyst is supported, or cordierite porcelain. The honeycomb-shaped catalyst carrier is coated with activated alumina such as γ-alumina, on which a noble metal such as platinum, palladium alloy, cobalt, nickel or the like as a catalyst is supported.

The catalyst poison adsorption filters 20 and 2
1 is to coat a honeycomb-shaped carrier made of, for example, cordierite porcelain or stainless steel with activated alumina such as γ-alumina, and further thereon, an alkali metal such as lithium Li, sodium Na, potassium K, and cesium Cs; A material carrying an alkaline earth metal such as magnesium Mg, calcium Ca, strontium Sr, and barium Ba is used. When an alkali metal or alkaline earth metal is supported on the carrier, it is preferably in the form of a carbonate or an acetate in an amount of about 0.01 to 0.5 mol, more preferably 0.2 to 0.1 mol per 100 g of activated alumina.
Amount of about 3 mol is attached and supported. In this case,
Since carbonic acid and acetic acid are both harmless substances, no harmful substances are emitted during the manufacturing process. In addition, even if these are used as the catalyst poison adsorption filters 20 and 21 without exhausting them from the carrier, the catalyst poisons contained in the exhaust gas are replaced by carbonic acid or acetic acid and the adsorption filters 20 and 21 are removed. The carbonic acid or acetic acid that has been adsorbed and displaced is discharged from the adsorption filters 20 and 21, so that the environment is not adversely affected. Further, the honeycomb-shaped carrier forming the catalyst poison adsorption filters 20 and 21 has a small pressure loss.
By providing the catalyst layer 21, the flow rate of the exhaust gas is not significantly reduced and the rectification is excellent, so that the catalyst layer 7
Exhaust gas can be uniformly flowed to A to 7C.

The above is an example of the configuration of the present invention, and its operation will be described next. When the catalytic combustion type heat storage exhaust gas treatment apparatus 1 of the present embodiment is used, for example, as an exhaust gas treatment apparatus for a coating and drying furnace, an exhaust gas duct (not shown) for guiding exhaust gas from the coating and drying furnace is connected to the untreated exhaust gas introduction ducts 8A to 8C. I do. Then, the automatic dampers 11A to 11C, 12
By operating A to 12C and 13A to 13C, the untreated exhaust gas introduced from one heat storage chamber 5A (5B, 5C) is purified by the exhaust gas heating chamber 3 and the catalyst layer 7B, and then the other heat storage chamber. 5B (5C, 5A), and the exhaust gas introduction side and discharge side are alternately switched in order to perform the processing continuously.

In this case, the untreated exhaust gas introduced into the heat storage chamber 5A (5B, 5C) is preheated by the heat stored in the heat storage layer 4 when passing through the heat storage layer 4, and the catalyst poison adsorption filter 20 , And reaches the catalyst layer 7A. At this time, the catalyst poison adsorbed at the temperature preheated by the heat storage layer 4 among the catalyst poisons included in the untreated exhaust gas is the catalyst layer 7A (7
B, 7C) before being captured by the catalyst poison adsorption filter 20. Therefore, when introducing untreated exhaust gas,
The catalyst poisons are hardly adsorbed on the catalyst layers 7A (7B, 7C) continuously arranged in the heat storage chambers 5A (5B, 5C) on the introduction side, and the catalyst life is extended.

The untreated exhaust gas introduced into the exhaust gas heating chamber 3 is heated to a predetermined processing temperature (300 to 450 ° C.) by a heating device 2 such as a gas burner and passes through a catalyst poison adsorption filter 21. Purification processing is performed in the catalyst layer 7B (7C, 7A). At this time, the catalyst poison adsorbed at the temperature heated in the exhaust gas heating chamber 3 and the catalyst poison generated by heating in the exhaust gas heating chamber 3 among the catalyst poisons contained in the untreated exhaust gas are the catalyst layers 7B Before reaching (7C, 7A), it is captured by the catalyst poison adsorption filter 21. Therefore, when the untreated exhaust gas heated in the exhaust gas heating chamber 3 is purified by the catalyst layer 7B (7C, 7A), almost no catalyst poison is adsorbed on the catalyst layer 7B (7C, 7A).
The catalyst life is extended.

As the catalyst poison adsorption filters 20 and 21, the honeycomb-shaped carrier formed of cordierite porcelain is coated with activated alumina such as γ-alumina, so that the exhaust gas and the catalyst poison adsorption filters 20, 21 are coated.
The contact area with the catalyst poison 21 is extremely large, and the catalyst poison adsorption efficiency is good. Further, in this example, the alkali metal or the alkaline earth metal is supported on the activated alumina. Therefore, even when considering that the alkali metal or the alkaline earth metal is somewhat neutralized by the activated alumina, the adsorption of the catalyst poison is performed. Filter 2
The surface of 0,21 shows strong alkalinity. Therefore,
Even when a large amount of strongly acidic silica is contained in the exhaust gas, the silica is adsorbed and neutralized by the alkaline catalyst poison adsorption filter, and the catalyst poisoning by silica is more effectively performed. Can be reduced.

The catalyst poison adsorption filters 20 and 21
May be replaced with a new one when the catalyst poison is adsorbed and becomes saturated. In this case, since the catalyst poison adsorption filters 20 and 21 do not use an expensive catalyst such as platinum, they are less expensive than the catalyst layers 7A to 7C. The cost is reduced as compared with the case where 7C is replaced.

In the above description, the case where an alkali metal or an alkaline earth metal is supported on a carrier coated with activated alumina as the catalyst poison adsorption filters 20 and 21 has been described. Instead of carrying the carrier, a carrier coated with activated alumina may be used as the catalyst poison adsorption filters 20 and 21. Activated alumina has both amphoteric properties, indicating alkalinity for acidic substances and acidity for basic (alkaline) substances. Therefore, it neutralizes and adsorbs catalyst poisons of any property. It has the effect of doing.

Further, the catalyst poison adsorption filters 20 and 21
Has been described on both the heat storage chambers 5A to 5C side of the catalyst layers 7A to 7C and the exhaust gas heating chamber 3 side, but the present invention is not limited to this. For example, when only the catalyst poison adsorbed at a relatively low temperature is contained in the untreated exhaust gas, the heat storage chambers 5A to 5C of the catalyst layers 7A to 7C are used.
It is sufficient to provide the catalyst poison adsorbing filter 20 only on the side, and when only the catalyst poison adsorbed at a relatively high temperature is contained in the untreated exhaust gas, the exhaust gas heating chamber 7 of the catalyst layers 7A to 7C is provided.
It is sufficient to provide the catalyst poison adsorption filter 21 only on the A to 7C sides, and when these are mixed and contained, they may be provided on both sides as described above. Furthermore, the case where the present invention is applied to a three-tower type catalytic combustion-type thermal storage exhaust gas treatment apparatus 1 in which three heat storage chambers 5A to 5C are arranged has been described. However, the present invention is not limited thereto, and a two-tower type, a four-tower type, Of course, it can be applied to a multi-tower type such as a six-tower type.

[0027]

As described above, according to the present invention, the catalyst poison contained in the exhaust gas is disposed on the heat storage chamber side or the exhaust gas heating chamber side before the exhaust gas passes through the catalyst layer. Since the catalyst poison adsorbing filter is adsorbed, the poisoning of the catalyst layer is reduced by that amount, and there is an excellent effect that the catalyst life is extended. In addition, the catalyst poison adsorption filter is less expensive than the catalyst layer because no expensive catalyst such as platinum is attached.
Therefore, even if the catalyst poison adsorption filter is frequently replaced,
There is an effect that the cost is reduced as compared with the case where the catalyst layer is replaced. Furthermore, as a catalyst poison adsorption filter, the carrier is coated with activated alumina such as γ-alumina, and the activated alumina has an extremely large surface area, so that there is an effect that the adsorption efficiency of a substance that becomes a catalyst poison is extremely high. At the same time, activated alumina has both amphoteric properties, indicating alkalinity for acidic substances and acidity for basic (alkaline) substances, and therefore neutralizes catalyst poisons of any nature. It has a very excellent effect of being efficiently adsorbed. Furthermore, if an alkali metal or an alkaline earth metal is supported on the activated alumina, the surface of the catalyst poison adsorption filter shows strong alkalinity, so that a large amount of silica showing strong acidity as catalyst poison is contained in the exhaust gas. Even if it is, the silica is adsorbed with high efficiency, and a very excellent effect that the catalyst poisoning by the silica can be significantly reduced can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a catalytic combustion type heat storage exhaust gas treatment apparatus according to the present invention.

FIG. 2 is a schematic explanatory view showing a conventional apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust gas processing apparatus 2 ... Heating apparatus 3 ... Exhaust gas heating chamber 4 ... Thermal storage layer 5A-5C ... Thermal storage chamber 6 ... ..Opening portions 7A to 7C..Catalyst layer 20, 21 ... Catalyst poison adsorption filter

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 53/86 B01J 23/02 ZABA B01J 23/02 ZAB B01D 53/36 G F23J 15/00 H F23J 15/00 J (72) Inventor Yoshihiro Sano 1-9-9 Kakimotocho, Toyota City, Aichi Prefecture Inside Trinity Industry Co., Ltd. (72) Inventor Kenji Sumita 7800 Chihama, Oto-cho, Ogasa-gun, Shizuoka Prefecture Inside Cataler Industry Co., Ltd.

Claims (1)

[Claims] A plurality of heat storage chambers (5A to 5A) having a heat storage layer (4) for recovering heat when discharging a high-temperature treated exhaust gas and preheating the exhaust gas when introducing a low-temperature untreated exhaust gas. 5C) is provided in parallel with an exhaust gas heating chamber (3) provided with a heating device (2) for heating the untreated exhaust gas to a predetermined temperature, and the exhaust gas heating chamber (3) and each heat storage layer (4) A catalyst layer (7A to 7C) for purifying by oxidizing, burning, or thermally decomposing flammable components contained in the untreated exhaust gas is formed between them, and is introduced from one heat storage chamber (5A to 5C). The untreated exhaust gas is supplied to the exhaust gas heating chamber (3) and the catalyst layer (7A ~
After purifying in 7C), the treated exhaust gas is exhausted from the other heat storage chambers (5A to 5C), and the exhaust gas introduction side and exhaust side are alternately switched in order to perform continuous treatment. In the exhaust gas treatment apparatus, the catalyst poison adsorption filters (20, 21) for adsorbing catalyst poisons contained in the exhaust gas are provided in the heat storage chambers (5A to 5C) of each of the catalyst layers (7A to 7C).
The catalyst poison adsorption filter (20, 21) is formed by coating the carrier with activated alumina, and is exchangeably mounted on one or both of the 5C) side and the exhaust gas heating chamber (3) side, or A catalytic combustion type heat storage exhaust gas treatment apparatus formed by supporting an alkali metal or an alkaline earth metal on a carrier coated with activated alumina.