JP5270912B2 - Catalytic oxidation treatment apparatus and catalytic oxidation treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst oxidation treatment device which is light in weight, compact, and low in running cost, and can suppress a deterioration caused by a catalyst poison and a catalyst oxidation treatment method using the device. <P>SOLUTION: In the treatment device for the oxidative decomposition of volatile organic compounds contained in exhaust gas by an oxidation catalyst, a pretreatment catalyst 3a for removing a trace quantity of the catalyst poison contained in the exhaust gas is set on the upstream side in the exhaust gas treatment direction, and a cooling mean 5 for lowering the temperature of the exhaust gas from the pretreatment catalyst is set in a gas passage connecting the pretreatment catalyst 3a and the oxidation catalyst 2a together. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a processing apparatus for volatile organic compounds, and in particular, a catalytic oxidation processing apparatus capable of suppressing deterioration of a catalyst even when a small amount of catalyst poison is contained in exhaust gas, and capable of processing economically and at low cost. And a catalytic oxidation treatment method.

  In various industries, harmful gases and malodorous components may be contained in the gas discharged from the manufacturing process.

  For example, volatile organic compounds (VOC) such as toluene, isopropyl alcohol (IPA), methyl ethyl ketone (MEK), and ethyl acetate are used in coating factories, printing factories, and film laminating factories. VOC-containing gas is discharged from equipment and facilities.

  From the viewpoint of preventing air pollution, in a process using VOC, in order to reduce the load on the environment, VOC gas generated from the process must be decomposed or removed as much as possible and discharged.

  As a gas purification method for decomposing or removing such VOC gas components, a direct combustion method in which the gas is directly burned by a burner, a catalytic combustion method in which the gas is burned by a catalyst, a regenerative combustion in which the heat is preheated and burned by a heat storage material The method is known.

  An outline of the catalytic combustion type apparatus is shown in FIG.

  The catalytic combustion apparatus shown in the figure is used at an intermediate temperature (about 250 to 350 ° C.), and the exhaust gas EG introduced from the exhaust gas inlet 50 is heated by a heater 52 disposed in the furnace chamber 51. Thereafter, the catalyst 53 is introduced into the catalyst 53 to be oxidatively decomposed and discharged from the exhaust gas outlet 54.

  The heat used for the oxidative decomposition of the exhaust gas EG by the catalyst 53 is lower than that in the direct combustion system.

  In the direct combustion method or the catalytic combustion method, what is desired when processing a dilute combustible component is to reduce the temperature of exhaust gas to be released and to reduce the amount of energy consumption and reduce the running cost.

  On the other hand, although the thermal storage combustion method has a higher initial cost than the other combustion methods described above, it can obtain a high heat recovery rate (generally 85% or more) and halves the energy consumption compared to the catalytic combustion method. There is an advantage that it can be suppressed.

  FIG. 13 shows an outline of a conventional heat storage combustion system.

  In the figure, in the heat storage combustion system, two towers of gas flow paths are provided for the furnace chamber 55. After the exhaust gas is burned and purified by the burner 56, a heat storage material 57 such as a ceramic honeycomb is installed downstream of the purification section. By doing so, it is configured to absorb exhaust heat. Then, by reversing the gas supply direction (from the A direction indicated by the solid line arrow to the B direction indicated by the broken line arrow), the heat stored in the heat storage material 57 is used again in the furnace chamber 55, and the heat storage provided on the opposite side The operation of recovering exhaust heat with the material 58 is repeated (for example, see Patent Document 1).

  In the figure, 59 is an exhaust gas inlet (or exhaust gas outlet), and 60 is an exhaust gas outlet (or exhaust gas inlet).

  The catalytic oxidative decomposition reaction catalyst used in the catalytic combustion system has a high oxidative decomposition activity at a low temperature, specifically, a noble metal such as platinum as an active component, and this is used as a catalyst carrier such as alumina. A supported one is used.

  These so-called noble metal-based catalysts are susceptible to poisoning substances such as organic silicon, and have a drawback that the oxidation activity is greatly reduced even if these poisoning substances are mixed in the exhaust gas in a trace amount. However, the present situation is that the development of a catalyst having sufficiently excellent durability for an organic silicon compound has not been made.

Therefore, in order to prevent catalyst deterioration, a method of adsorbing and removing the organic silicon compound by installing an adsorbent in the previous stage of the catalyst is widely adopted.
Japanese Patent Laid-Open No. 11-44416

  However, in general, the method of removing the organosilicon compound with the adsorbent requires replacement of the adsorbent or removal of the adsorbate by regeneration when the adsorption amount in the adsorbent reaches saturation. In order to maintain, there is a problem that the adsorbent must be periodically replaced and the running cost is high.

  On the other hand, the heat storage combustion type gas purification treatment method that recovers the heat of the gas that has been heated during the oxidative decomposition process and reuses it as a preheating source for untreated exhaust gas is more efficient than other gas purification treatment methods in terms of running cost. Although advantageous, the above-described heat storage combustion system effective for energy saving also has the following problems.

  That is, even if the heat stored in the exhaust gas is effectively absorbed by the regenerative combustion method, the heat capacity of the sensible heat storage material is limited, so a large amount of sensible heat storage material is required to obtain high thermal efficiency. As a result, the weight and size of the device are increased, and the installation location is limited. In addition, since it has a large heat capacity, it takes time for the device to stabilize.

  The present invention has been made in consideration of the problems associated with the conventional combustion gas purification device described above, and can be configured to be lightweight and compact, and can suppress initial costs and running costs, and can be organic. The present invention provides a catalytic oxidation treatment apparatus and a catalytic oxidation treatment method capable of maintaining a high purification rate for a longer time even with respect to exhaust gas containing a catalyst poisoning substance such as a silicon compound.

(a) Catalytic oxidation treatment apparatus The catalytic oxidation treatment apparatus of the present invention removes a catalyst poison contained in a trace amount in the exhaust gas in a catalytic oxidation treatment apparatus that oxidizes and decomposes volatile organic compounds contained in the exhaust gas with an oxidation catalyst. And a cooling means for lowering the exhaust gas temperature from the pretreatment catalyst is interposed in the gas flow path connecting the pretreatment catalyst and the oxidation catalyst. (See FIG. 1 (corresponding diagram of claim 1)).

  In the catalytic oxidation treatment apparatus, heating means can be provided in the upstream gas flow path of the pretreatment catalyst (see FIG. 2 (corresponding to claim 2)).

  The cooling means includes a first heat exchanger for exchanging heat between the exhaust gas from the pretreatment catalyst outlet and the untreated exhaust gas, and the first heat exchanger outlet and the pretreatment catalyst inlet of the untreated exhaust gas are gasses. It can be connected by a flow path. (See FIG. 3 (corresponding diagram of claim 3)).

  If this structure is followed, the refrigerant | coolant (cooling water) in a cooling means becomes unnecessary by cooling the waste gas from a pre-processing catalyst by heat exchange with an untreated waste gas.

  And a second heat exchanger for heating the untreated exhaust gas by exchanging heat between the untreated exhaust gas and the purified gas from the oxidation catalyst, and a second heat exchanger outlet and a pretreatment catalyst inlet for the untreated exhaust gas. Can be connected by a gas flow path (see FIG. 4 (corresponding view of claim 4)).

  According to this configuration, heat exchange between the untreated exhaust gas and the oxidation catalyst outlet gas (clean exhaust gas) eliminates the need for a heating means for the pretreatment catalyst or reduces the energy required for heating. Further, the temperature of the oxidation catalyst outlet gas can be lowered.

  When the first heat exchanger that performs heat exchange between the outlet exhaust gas of the pretreatment catalyst and the untreated exhaust gas is provided as the cooling means, the first heat exchanger outlet of the untreated exhaust gas and the first heat exchanger of the untreated exhaust gas The two heat exchanger inlets can be connected by a gas flow path (see FIG. 5A (corresponding diagram of claim 5)).

  According to this configuration, the refrigerant (cooling water) in the cooling means can be made unnecessary, the heating means for the pretreatment catalyst is unnecessary, or the energy required for heating can be reduced.

  Alternatively, a second heat exchanger outlet gas for exchanging heat between the untreated exhaust gas and the purified gas from the oxidation catalyst is introduced into the first heat exchanger inlet provided as a cooling means for the pretreatment catalyst outlet gas. It can be connected by a gas flow path, and further can be connected by a gas flow path for introducing untreated exhaust gas at the outlet of the first heat exchanger to the pretreatment catalyst inlet (FIG. 5B) (corresponding to claim 6). reference).

  If this structure is followed, the refrigerant | coolant (cooling water) in a cooling means can be made unnecessary.

  The first heat exchanger is preferably constituted by an orthogonal heat exchanger.

  The second heat exchanger is preferably constituted by an orthogonal heat exchanger.

  Further, the heating means can be provided in a gas flow path connecting the outlet of the first heat exchanger for the untreated exhaust gas and the inlet of the pretreatment catalyst (a claim dependent on claim 3). 9)))).

  Alternatively, the second heat exchanger outlet gas is connected by a gas flow path for introduction into the first heat exchanger inlet provided as a cooling means for the pretreatment catalyst outlet gas, and the first heat exchanger outlet is untreated. A heating means may be provided in the gas flow path for introducing the exhaust gas into the pretreatment catalyst inlet (see FIG. 6B (corresponding diagram of claim 9 subordinate to claim 6)).

  According to this configuration, the cooling water in the cooling means (first heat exchanger) is not necessary, and the energy required for heating the pretreatment catalyst can be reduced.

  Further, the heating means may be provided in a gas flow path connecting the second heat exchanger outlet of the untreated exhaust gas and the pretreatment catalyst inlet (FIG. 7 (Claim 10 dependent on Claim 4). Corresponding diagram) and FIG. 8 (refer to the corresponding diagram of claim 10 subordinate to claim 5).

  In addition, a temperature sensor for measuring the exhaust gas temperature at the outlet of the second heat exchanger or the exhaust gas temperature at the inlet side of the oxidation catalyst is provided, and the heating operation of the heating unit is controlled based on the gas temperature measured by the temperature sensor. By doing, it can comprise so that the exhaust gas by which the gas temperature was heat-maintained at 400-700 degreeC may be introduce | transduced into the said pretreatment catalyst.

(b) Catalytic oxidation treatment method The catalytic oxidation treatment method of the present invention is a treatment method in which a volatile organic compound contained in exhaust gas is oxidized and decomposed with an oxidation catalyst, and the catalyst poison contained in a trace amount in the exhaust gas is decomposed or removed. Therefore, from one or more selected from the group of metals or metal oxides such as manganese, aluminum, palladium, iron, copper, silver, calcium, sodium, cobalt, nickel, cerium, indium, tungsten, magnesium, tin The gist of the present invention is to use a pretreatment catalyst to be heated to 400 to 700 ° C. to decompose or remove the poisoning substance and then oxidatively decompose the volatile organic compound.

  In the catalytic oxidation treatment method, instead of the metal or metal oxide, an inorganic adsorbent such as zeolite, activated alumina or clay mineral is used as a pretreatment catalyst, and exhaust gas containing a small amount of catalyst poison and volatile organic compound is treated. The exhaust gas after the treatment can be oxidized using a Pd or Pt catalyst. Among the inorganic adsorbents, zeolite is preferable because it has a large specific surface area and is excellent in adsorption power and heat resistance.

  Further, the catalytic oxidation treatment method of the present invention introduces untreated exhaust gas into a pretreated catalyst for removing a catalyst poison contained in a trace amount in the exhaust gas, and cools the exhaust gas discharged from the pretreated catalyst to a predetermined temperature. Then, the gist is to further introduce the cooled exhaust gas into the oxidation catalyst to oxidatively decompose the volatile organic compound contained in the exhaust gas.

  In the catalytic oxidation treatment method, the predetermined temperature is preferably 200 to 500 ° C.

  Moreover, the untreated exhaust gas can be heated by exchanging heat between the exhaust gas discharged from the pretreated catalyst and the untreated exhaust gas, and introduced into the pretreated catalyst.

  Further, the untreated exhaust gas heated and supplied for cooling the exhaust gas discharged from the pretreatment catalyst is further used for heat exchange with the exhaust gas discharged from the oxidation catalyst, to preheat the untreated exhaust gas, It can be introduced into the pretreatment catalyst.

  Moreover, the untreated exhaust gas can be heated by introducing heat exchange between the exhaust gas discharged from the oxidation catalyst and the untreated exhaust gas, and introduced into the pretreatment catalyst.

  Further, the untreated exhaust gas heated by exchanging heat with the exhaust gas discharged from the oxidation catalyst is further used for heat exchange with the exhaust gas discharged from the pretreatment catalyst, and the untreated gas is sufficiently preheated, It can be introduced into the pretreatment catalyst.

  Moreover, after the untreated exhaust gas to be introduced into the pretreatment catalyst is heated by a heating means, it can be introduced into the pretreatment catalyst.

  The present invention is advantageous in that it is light and compact, has a low running cost, and can suppress deterioration against catalyst poison.

  Hereinafter, an embodiment of a catalytic oxidation treatment apparatus according to the present invention will be described with reference to the drawings.

a. Basic Configuration of Processing Apparatus FIG. 9 is a block diagram showing the configuration of the catalytic oxidation processing apparatus according to the present invention.

  In the figure, a catalytic oxidation treatment apparatus 1 includes a catalyst layer 2 filled with a metal-supported oxidative decomposition catalyst (oxidation catalyst) 2a for oxidizing and decomposing VOC exhaust gas containing a trace amount of an organic silicon compound, and the catalyst in the exhaust gas treatment direction. Provided upstream of the layer 2, provided with a pretreatment layer 3 filled with a pretreatment catalyst 3 a for adsorbing and decomposing an organosilicon compound contained in the exhaust gas, and provided upstream of the pretreatment layer 3, The heating means 4 for heating the pretreatment catalyst 3a to a temperature sufficient to decompose the organosilicon compound, and the pretreatment layer 3 and the catalyst layer 2 are provided between the pretreatment layer 3 and the organosilicon compound. The cooling means 5 is mainly configured to lower the exhaust gas temperature after adsorbing and decomposing the catalyst to a temperature suitable for oxidative decomposition of VOC by the subsequent oxidation decomposition catalyst 2a. In the figure, 6 is an exhaust gas inlet and 7 is an exhaust gas outlet.

  As the oxidative decomposition catalyst 2a filled in the catalyst layer 2 and the pretreatment catalyst 3a filled in the pretreatment layer 3, VOC in exhaust gas can be oxidatively decomposed. For example, platinum, titanium, manganese, aluminum A general oxidative decomposition catalyst made of a metal or a metal oxide such as palladium, iron, copper, silver, calcium, sodium, cobalt, nickel, cerium, indium, tungsten, magnesium, or tin can be applied.

  Further, as the pretreatment catalyst, an inorganic adsorbent such as zeolite, activated alumina, clay mineral or the like can be used.

  The temperature at which VOC exhaust gas is oxidatively decomposed with a catalyst is generally controlled at a temperature (medium temperature) of 250 to 350 ° C. in consideration of the durability of the catalyst. However, if the exhaust gas contains a catalyst poison such as an organic silicon compound even in a trace amount, the oxidation activity of the catalyst is significantly reduced at the above-described temperature.

  Therefore, the organic silicon compound is removed by the pretreatment catalyst 3a provided separately from the oxidative decomposition catalyst 2a. In order to effectively remove the organosilicon compound with the pretreatment catalyst 3a, it is desirable to perform the treatment at 400 to 600 ° C. (high temperature). When the temperature is lower than 400 ° C., the oxidative decomposition efficiency of the organic silicon compound decreases. When the temperature exceeds 600 ° C., the adsorptivity of the organic silicon to the pretreatment catalyst 3a decreases, and the heat resistance and economic efficiency decrease. Problems arise.

  Therefore, as the pretreatment catalyst 3a, it is preferable to use palladium-based and manganese or copper oxides that are excellent in durability at high temperatures.

  In addition, a gas or electric heater can be used as the heating unit 4, and a gas cooler (first heat exchanger) using cooling water can be used as the cooling unit 5.

a-1. Treatment Operation According to the catalytic oxidation treatment apparatus 1 having the above configuration, the organosilicon compound-containing VOC exhaust gas G introduced from the exhaust gas inlet 6 can be effectively decomposed by the heating means 4. After the temperature is raised to the temperature, it is introduced into the pretreatment layer 3 filled with the pretreatment catalyst 3a, and the organosilicon compound is decomposed.

  Next, the exhaust gas G ′ at the outlet of the pretreatment catalyst 3a of the pretreatment layer 3 is introduced into the cooling means 5, so that the temperature is lowered to a temperature suitable for oxidative decomposition of the VOC by the oxidative decomposition catalyst 2a. Is introduced into the catalyst layer 2 filled with the oxidative decomposition catalyst 2a, whereby the VOC is oxidatively decomposed, and the treated purified gas is discharged from the exhaust gas outlet 7.

b. Overall Configuration of Processing Apparatus FIG. 10 is a block diagram showing the overall configuration of the catalytic oxidation processing apparatus.

  In the overall configuration shown in the figure, the catalytic oxidation treatment apparatus 10 includes a catalyst layer 2 filled with a metal-supported oxidative decomposition catalyst 2a for oxidizing and decomposing a VOC exhaust gas containing a trace amount of an organic silicon compound, and the above-mentioned in the exhaust gas treatment direction. A pretreatment layer 3 provided on the upstream side of the catalyst layer 2 and filled with a pretreatment catalyst 3a for adsorbing and decomposing an organosilicon compound contained in the exhaust gas; and the pretreatment layer 3 and the catalyst layer 2 The first heat exchanger 11 interposed therebetween, the second heat exchanger 12 disposed on the downstream side of the catalyst layer 2, and the organic silicon compound provided on the upstream side of the pretreatment layer 3 are decomposed. Heating means 4 for heating the exhaust gas to a sufficient temperature.

  The first and second heat exchangers 11 and 12 are orthogonal heat exchangers, and the first heat exchanger 11 corresponds to the cooling means 5 shown in FIG.

  In the figure, 6 is an exhaust gas inlet, and 7 is an exhaust gas outlet.

  In addition, as the oxidative decomposition catalyst 2a filled in the catalyst layer 2 and the pretreatment catalyst 3a filled in the pretreatment layer 3, the same or the same type of catalyst as described in FIG. 9 is used.

  Further, the heating means 4 can also be constituted by a heater using gas or electricity, like the heating means described in FIG.

b-1. Treatment Operation Untreated VOC exhaust gas G containing an organic silicon compound introduced from the exhaust gas inlet 6 is downstream of the pretreatment layer 3 filled with the pretreatment catalyst 3a, and the oxidation decomposition catalyst 2a. Is passed through the first heat exchanger 11 provided upstream of the catalyst layer 2 filled with.

  The exhaust gas G that has passed through the first heat exchanger 11 is then passed through the second heat exchanger 12 provided on the downstream side of the catalyst layer 2 through the gas flow path 13, and then through the gas flow path 14. And introduced into the pretreatment layer 3 filled with the pretreatment catalyst 3a.

  The organosilicon compound introduced into the pretreatment layer 3 is decomposed by the pretreatment catalyst 3a, and then the outlet gas of the pretreatment layer 3 is introduced into the first heat exchanger 11 through the gas flow path 15 to introduce the exhaust gas. Heat exchange with the untreated exhaust gas G supplied from the port 6 is performed.

  The gas flow path 14 is provided with a heating means 4, and the exhaust gas heated to a temperature sufficient to decompose the organic silicon compound (400 to 700 ° C.) is introduced into the pretreatment layer 3. Due to the adsorption / decomposition of the organosilicon compound in the pretreatment catalyst 3a, the outlet exhaust gas temperature of the pretreatment layer 3 (in the gas flow path 15) becomes higher than the inlet exhaust gas temperature of the pretreatment layer 3.

  Since the temperature of the exhaust gas G discharged from the factory production process or the like is usually about 30 to 60 ° C., the outlet exhaust gas of the pretreatment layer 3 is heat-exchanged with the untreated exhaust gas G in the first heat exchanger 11. On the other hand, the untreated exhaust gas introduced from the exhaust gas inlet 6 is heated.

  Thus, the VOC gas after the decomposition of the organosilicon compound heat-exchanged by the first heat exchanger 11 is cooled to 250 to 350 ° C. suitable for decomposing VOC by the oxidative decomposition catalyst 2a, and the gas flow path 16 Is introduced into the oxidative decomposition catalyst 2a of the catalyst layer 2. As a result, VOC is oxidized and decomposed into purified gas.

  The purified gas whose temperature has risen due to the heat of decomposition accompanying the oxidative decomposition in the catalyst layer 2 is introduced into the second heat exchanger 12 provided on the downstream side of the catalyst layer 2 via the gas flow path 17, and the second Heat exchange (cooling) is performed by the heat exchanger 12, and the exhaust gas is discharged to the atmosphere.

  On the other hand, the other exhaust gas supplied from the second heat exchanger 12 for heat exchange (supplied from the gas flow path 13) is heated and supplied to the heating means 4. In the heating means 4, the exhaust gas is heated and maintained at a temperature (400 to 700 ° C.) at which the organosilicon compound can be sufficiently adsorbed and decomposed by the pretreatment catalyst 3 a and introduced into the pretreatment layer 3.

  In addition, when the temperature of the untreated exhaust gas whose temperature has been raised by heat exchange in the first heat exchanger 11 is a temperature suitable for treatment with the pretreatment catalyst 3a, the pretreatment layer 3 is directly used. When the temperature of the pretreatment catalyst 3a is less than the temperature that can be treated, the temperature of the untreated exhaust gas can be heated via the heating means 4 (see FIG. 6 (a)). )reference).

  Although the processing temperature of each part of the catalytic oxidation processing apparatus 10 varies depending on the concentration of the VOC exhaust gas, an example is as follows.

  For example, when the exhaust gas temperature heated by the heating means 4 and introduced into the pretreatment layer 3 is 500 ° C., the outlet temperature of the pretreatment layer 3 is about 550 ° C.

  Next, the exhaust gas is introduced into the first heat exchanger 11, and is cooled to about 300 ° C. by heat exchange with the untreated exhaust gas G by the first heat exchanger 11.

  The cooled exhaust gas is then introduced into the catalyst layer 2, VOC is oxidatively decomposed by the oxidative decomposition catalyst 2a, and discharged from the catalyst layer 2 as a purified gas. The purified gas at about 700 ° C. is then introduced into the second heat exchanger 12, cooled to about 510 ° C. and then released.

  On the other hand, the exhaust gas supplied through the gas flow path 13 and heated to 500 ° C. by the second heat exchanger 12 is supplied to the heating means 4 through the gas flow path 14, and the pretreatment catalyst of the pretreatment layer 3. 3a.

  In this case, if the exhaust gas temperature raised by the second heat exchanger 12 is 500 ° C. as described above, it has already reached the treatment temperature at which the organosilicon compound can be sufficiently adsorbed and decomposed. The heating operation by the heating means 4 is not necessary.

  That is, the catalytic oxidation treatment apparatus 10 of the present embodiment is configured to control the heating unit 4 according to the exhaust gas temperature after oxidative decomposition. For example, the exhaust gas temperature from the second heat exchanger 12 or the front A temperature sensor for detecting the temperature of the exhaust gas introduced into the processing catalyst 3a is provided, and the heating means 4 is configured to be ON / OFF controlled based on a temperature signal output from the temperature sensor.

  Specifically, a bypass flow path 18 of the first heat exchanger 11 is provided between the gas flow paths 6-13 on the heat receiving side of the first heat exchanger 11 or between the gas flow paths 15-16 on the heat dissipation side (in the drawing, the heat receiving heat is received). The bypass flow path 18 that bypasses the gas flow path 6-13 on the side is shown), and an automatic control damper 19 is installed in the bypass flow path 18 and the temperature of the exhaust gas introduction flow path 16 to the catalyst layer 2 is detected. The exhaust gas temperature of the gas flow path 16 can be controlled by providing the temperature sensor 20 to be controlled and controlling the opening degree of the automatic control damper 19 based on the temperature signal output from the temperature sensor 20.

  Further, a bypass flow path 21 of the second heat exchanger 12 is provided between the gas flow paths 13-14 on the heat receiving side of the second heat exchanger 12 or between the gas flow paths 17-7 on the heat dissipation side (in the figure, the heat receiving side). The gas flow path 14 for introducing the exhaust gas to the pretreatment layer 3 while installing the automatic control damper 22 in the bypass flow path 21 is shown. A temperature sensor 23 for detecting the temperature of the gas is provided, and the exhaust gas temperature in the gas flow path 14 is controlled by controlling the opening degree of the automatic control damper 22 based on the temperature signal output from the temperature sensor 23. You can also.

  In FIG. 10, for convenience, the bypass channel 18 or the bypass channel 21 that is selectively provided is shown on the same drawing.

  The heating means is not limited to ON-OFF control, and the heating means 4 is proportional to the difference between the control amount and the set temperature by comparing the measured temperature detected by the temperature sensor with the preset temperature set in the memory. So-called proportional control may be performed.

  In this way, if the bypass passages 18 and 21 are provided so that the exhaust gas temperature flowing through the gas passage 16 and the gas passage 14 can be controlled, the ON operation of the heating means 4 can be minimized. , Thereby saving energy.

  As described above, the catalytic oxidation treatment apparatus 10 shown in FIG. 10 recovers the decomposition heat generated by the oxidative decomposition of VOC with the second heat exchanger 12 and uses it together with the auxiliary heating means 4. The organic silicon compound is decomposed by the pretreatment catalyst 3a (see FIG. 8).

  Further, in FIG. 10, the exhaust gas from the first heat exchanger 11 is introduced into the second heat exchanger 12 through the gas flow path 13, but the second heat exchanger 12 is provided independently so as to take in the untreated exhaust gas. The exhaust gas from the second heat exchanger 12 can be heated by the heating means 4 and then introduced into the pretreatment layer 3 (see FIG. 7).

  Further, the above-described catalytic oxidation treatment apparatus 10 basically has a one-pass gas flow and does not require a damper for switching the gas flow path. Therefore, the apparatus can be configured very simply. Therefore, it is advantageous in terms of cost as compared with the conventional heat storage combustion system.

  Further, since the pretreatment catalyst 3a for combating the catalyst poison and the oxidative decomposition catalyst 2a for VOC decomposition are filled in separate layers, the catalyst filling amount can be arbitrarily set, and the catalyst can be replaced. There is an advantage that less labor is required.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to these Examples. In addition, evaluation of this invention was performed with the catalytic oxidation processing apparatus shown in FIG.

  A ceramic honeycomb having a specific gravity of 0.45 g / cc carrying activated alumina is applied to the pretreatment catalyst 3a, and a cordierite honeycomb having a specific gravity of 0.65g / cc carrying 0.4 wt.% Of palladium on the oxidative decomposition catalyst 2a. Adapted.

Next, 60 ° C. air containing 3000 ppm of toluene and 2 ppm of hexamethyldisilazane was introduced as an organic silicon compound-containing VOC gas G from the exhaust gas inlet 6 at an air flow rate of 10 m ³ / min. The gas concentration at the exhaust gas outlet 7 was continuously measured with a total hydrocarbon meter, and the change over time in the removal rate η (%) of the apparatus was confirmed.

  Here, the removal rate η (%) = (exhaust gas inlet port gas concentration−exhaust gas outlet gas concentration) / exhaust gas inlet gas concentration × 100.

  The space velocity SV of the pretreatment catalyst 3a is 40000 (1 / hr), the space velocity of the oxidative decomposition catalyst 2a is 40000 (1 / hr), and the pretreatment layer is heated to 500 ° C. by applying an electric heater as the heating means 4. 3 was introduced.

  FIG. 11 is a graph showing the change over time of the removal rate.

  In the graph, the initial removal rate η immediately after the start of operation is 99.9%, which shows extremely high performance. The temperature of the gas flow path 15 at this time is 550 ° C., the temperature of the gas flow path 16 after being introduced into the first heat exchanger 11 and subjected to heat exchange is 300 ° C., and the exhaust gas having this gas temperature is converted into the catalyst tank 2 To be introduced. It becomes 700 degreeC in the gas flow path 17 after an oxidative decomposition process.

  Thus, the temperature difference between the inlet and outlet of the oxidative decomposition catalyst 2a can be increased by dividing into the pretreatment catalyst 3a and the oxidative decomposition catalyst 2a and once cooling between them. Thereby, even if the temperature rise during the oxidative decomposition of VOC is large, the oxidative decomposition catalyst can be treated at a temperature lower than the heat resistant temperature, and the effect of extending the life is enhanced even if the organic silicon compound is contained in the exhaust gas. Moreover, even if the temperature of the pretreatment catalyst 3a is increased to 500 ° C., it is possible to treat high concentration VOC.

  In addition, the temperature of the exhaust gas outlet 7 is 510 ° C. after the heat exchange after being introduced into the second heat exchanger 12. After being introduced into the first heat exchanger 11 through the exhaust gas inlet 6 and exchanging heat, the exhaust gas temperature in the gas flow path 13 is 300 ° C. After being introduced into the second heat exchanger 12 and exchanging heat, the gas flow The temperature of the path 14 is 500 ° C. Since heat recovery is sufficiently performed at this stage, it is not necessary to use the electric heater (heating means) 4 in full, and electric power can be greatly reduced.

  In addition, because the pretreatment catalyst 3a was heated to a high temperature, the removal rate was reduced to 99%, whereas the pretreatment catalyst temperature was 100 min at 300 ° C. (treatment time at point C in the graph). By setting the temperature to 500 ° C., the life of the oxidative decomposition catalyst by the organosilicon compound was maintained for about 400 times (treatment time at point D in the graph) and about 4 times.

It is a schematic diagram which shows the basic composition of the catalytic oxidation treatment apparatus of this invention. It is a schematic diagram which shows the structure which added the heating means to the structure of FIG. It is a schematic diagram which shows the structure provided with the 1st heat exchanger as a cooling means of FIG. It is a schematic diagram which shows the structure provided with the 2nd heat exchanger in the structure of FIG. (a) And (b) is a schematic diagram which shows the structure provided with the 1st heat exchanger as a cooling means. (a) is a schematic diagram showing a configuration in which heating means is provided in the gas flow path of FIG. 3, and (b) is a configuration in which heating means is provided in the gas flow path of FIG. 5 (b). It is a schematic diagram which shows the structure which provided the heating means in the gas flow path of FIG. It is a schematic diagram which shows the structure which provided the heating means in the gas flow path of Fig.5 (a). It is a block diagram which shows the basic composition of the catalytic oxidation processing apparatus which concerns on this invention. It is a block diagram which shows the whole structure of the catalytic oxidation processing apparatus which concerns on this invention. It is a graph which shows the time-dependent change of the removal rate by this invention. It is explanatory drawing which shows schematic structure of the conventional catalytic combustion system. It is explanatory drawing which shows schematic structure of the conventional heat storage combustion system.

Explanation of symbols

1 catalytic oxidation treatment device 2 catalyst layer 2a oxidation decomposition catalyst (oxidation catalyst)
DESCRIPTION OF SYMBOLS 3 Pretreatment layer 3a Pretreatment catalyst 4 Heating means 5 Cooling means 6 Exhaust gas inlet 7 Exhaust gas outlet 10 Catalytic oxidation treatment device 11 First heat exchanger 12 Second heat exchanger 13 Gas flow path 14 Gas flow paths 15 to 17 Gas flow path 18 Bypass flow path 19 Automatic control damper 20 Temperature sensor 21 Bypass flow path 22 Automatic control damper 23 Temperature sensor

Claims (18)

In catalytic oxidation treatment equipment that oxidatively decomposes volatile organic compounds contained in exhaust gas with an oxidation catalyst
A pretreatment catalyst for removing an organic silicon compound contained in a trace amount in the exhaust gas is provided upstream of the oxidation catalyst in the exhaust gas treatment direction, and a gas flow path connecting the pretreatment catalyst and the oxidation catalyst. A catalytic oxidation treatment apparatus, characterized in that a cooling means for lowering the exhaust gas temperature from the pretreatment catalyst is interposed.   The catalytic oxidation treatment apparatus according to claim 1, wherein heating means is provided in an upstream gas flow path of the pretreatment catalyst.   The cooling means includes a first heat exchanger for exchanging heat between the exhaust gas from the pretreatment catalyst outlet and the untreated exhaust gas, and the first heat exchanger outlet of the untreated exhaust gas and the pretreatment catalyst inlet are gas flow paths. The catalytic oxidation treatment apparatus according to claim 1, which is connected at a point.   It has a second heat exchanger that heats the untreated exhaust gas by exchanging heat between the untreated exhaust gas and the purified gas from the oxidation catalyst, and the second heat exchanger outlet of the untreated exhaust gas and the pretreatment catalyst inlet are The catalytic oxidation treatment apparatus according to claim 1, which is connected by a gas flow path.   The cooling means includes a first heat exchanger for exchanging heat between the outlet exhaust gas of the pretreatment catalyst and the untreated exhaust gas, and the first heat exchanger outlet of the untreated exhaust gas and the second heat exchanger of the untreated exhaust gas The catalytic oxidation treatment apparatus according to claim 4, wherein the inlet is connected by a gas flow path.   It has a second heat exchanger that heats the untreated exhaust gas by exchanging heat between the untreated exhaust gas and the purified gas from the oxidation catalyst, and the second heat exchanger outlet of the untreated exhaust gas and the first heat exchange The catalytic oxidation treatment apparatus according to claim 3, wherein the vessel inlet is connected by a gas flow path. The catalytic oxidation treatment apparatus according to any one of claims 3 , 5, and 6, wherein the first heat exchanger is configured by an orthogonal heat exchanger.   The catalytic oxidation treatment apparatus according to any one of claims 4 to 6, wherein the second heat exchanger is configured by an orthogonal heat exchanger. Catalytic oxidizing apparatus according to claim 3 or 6, wherein the pressurized heat means the gas flow path which connects the first heat exchanger outlet of the raw exhaust gas and the pretreatment catalyst inlet is provided. Catalytic oxidizing apparatus according to claim 4 or 5 raw exhaust gas of the second heat exchanger outlet and the pre-treatment catalyst inlet and pressurized heating means to the gas flow path connecting the is provided.   A temperature sensor for measuring the exhaust gas temperature at the outlet of the second heat exchanger or the exhaust gas temperature at the inlet side of the oxidation catalyst, and controlling the heating operation of the heating means based on the gas temperature measured by the temperature sensor The catalytic oxidation treatment apparatus according to claim 10, wherein the exhaust gas whose gas temperature is heated and maintained at 400 to 700 ° C. is introduced into the pretreatment catalyst.   An untreated exhaust gas is introduced into a pretreatment catalyst for removing organic silicon compounds contained in a trace amount in the exhaust gas, the exhaust gas discharged from the pretreatment catalyst is cooled to a predetermined temperature, and the cooled exhaust gas is further used as an oxidation catalyst. A catalytic oxidation treatment method comprising introducing and oxidatively decomposing a volatile organic compound contained in exhaust gas.   The catalytic oxidation treatment method according to claim 12, wherein the predetermined temperature is 200 to 500 ° C.   The catalytic oxidation treatment method according to claim 12 or 13, wherein the untreated exhaust gas is heated by exchanging heat between the exhaust gas discharged from the pretreated catalyst and the untreated exhaust gas, and introduced into the pretreated catalyst.   The untreated exhaust gas heated for use in cooling the exhaust gas discharged from the pretreatment catalyst is further used for heat exchange with the exhaust gas discharged from the oxidation catalyst to preheat the untreated exhaust gas, The catalytic oxidation treatment method according to claim 14, which is introduced into the treatment catalyst.   The catalytic oxidation treatment method according to claim 12 or 13, wherein the untreated exhaust gas is heated by exchanging heat between the exhaust gas discharged from the oxidation catalyst and the untreated exhaust gas and introduced into the pretreatment catalyst.   The untreated exhaust gas heated by exchanging heat with the exhaust gas discharged from the oxidation catalyst is further used for heat exchange with the exhaust gas discharged from the pretreatment catalyst, and the pretreatment is performed by sufficiently preheating the untreated exhaust gas. The catalytic oxidation treatment method according to claim 14, wherein the catalytic oxidation treatment method is introduced into the catalyst. The catalytic oxidation treatment method according to any one of claims 12 to 17, wherein the untreated exhaust gas to be introduced into the pretreatment catalyst is heated by a heating means and then introduced into the pretreatment catalyst.

Images