JP2010214280A - Deodorizer and deodorization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deodorizer and a deodorization method, capable of highly efficiently removing volatile organic compounds from an exhaust gas containing various volatile organic compounds and reducing environmental loads. <P>SOLUTION: The deodorizer of the exhaust gas containing the volatile organic compounds includes an adsorption device for adsorbing and removing aromatic compounds in the exhaust gas, and a biological deodorizer for receiving the supply of the exhaust gas from which the aromatic compounds are adsorbed and removed from the adsorption device and biodegrading the remaining volatile organic compounds. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a deodorizing apparatus for exhaust gas containing a volatile organic compound discharged from a process using a volatile organic compound such as paint, varnish, ink, etc., and a heat treatment process of the volatile organic compound. And a deodorizing method.

  As a deodorizing method for removing VOC from exhaust gas containing a volatile organic compound (hereinafter sometimes referred to as “VOC”) that is a component of odor and is a causative substance of a photochemical oxidant or suspended particulate matter, a combustion method, There are physicochemical methods such as a chemical cleaning method and an adsorption method, and biological methods such as a soil deodorization method and an activated sludge method (see Patent Documents 1 and 2).

JP-A-8-299749 JP 2002-153723 A

While the combustion method and the chemical cleaning method can remove VOC at a high removal rate, there are problems. That is, in the combustion method, there are problems that operation costs such as fuel costs increase, and carbon dioxide is generated due to fuel combustion, resulting in a large secondary environmental load.
In addition, the chemical cleaning method has a problem that the operation cost such as the chemical solution to be used increases and the reaction product after the cleaning process needs to be processed.

Biological treatment methods for degrading VOCs by microorganisms have recently attracted attention because of their low running costs and low environmental impact such as low secondary products. However, in this biological treatment method, it is difficult to decompose and to obtain high removal efficiency with respect to hydrophobic, poorly water-soluble volatile organic compounds or aromatic compounds.
Moreover, even if it is VOC which can be biologically processed, the microbe group which processes those VOC is bacteria which uses the carbon in VOC to be processed as a nutrient source, and generally shows a big growth rate. Therefore, when the concentration of VOC in the exhaust gas is high (for example, several tens of ppm to several hundreds of ppm), microorganisms actively grow, the number of microorganisms increases, the microbial density of the microbial packed bed increases, and the microbial packed bed is accommodated. The pressure loss of the biological deodorization apparatus thus increased may cause troubles in the flow of exhaust gas, and may cause troubles such as reduction in contact efficiency between the exhaust gas and microorganisms. Such an active growth phenomenon of microorganisms is likely to occur in the case of exhaust gas having a high VOC content with a large number of carbons per molecule (high molecular weight) so that the nutrients obtained by the microorganisms increase.

As another deodorization method for VOC, there is an adsorption removal method using an adsorbent such as activated carbon. This adsorptive removal method is suitable for removing organic compounds having a large molecular weight and a high boiling point, and in some cases, an impregnated activated carbon in which a chemical is attached to the surface is used in order to further improve the adsorptivity of acidic gas and basic gas.
However, in this adsorption removal method, when various types of VOCs are contained in the exhaust gas, it is often difficult to remove all VOCs with high efficiency, particularly low molecular weight organic compounds, There is a problem in that high removal efficiency cannot always be obtained for VOCs that are not suitable for the characteristics of the activated carbon and the type of the attached agent.

  The present invention has been made in view of the above problems, and can remove a volatile organic compound from exhaust gas containing various types of volatile organic compounds with high efficiency, and a deodorizing apparatus with a low environmental load and It aims at providing the deodorizing method.

(1) A deodorization apparatus according to the present invention is an exhaust gas deodorization apparatus containing a volatile organic compound, and adsorbs and removes aromatic compounds in the exhaust gas, and adsorbs aromatic compounds from the adsorption apparatus. And a biological deodorizing device for biodegrading the remaining volatile organic compounds upon receiving the supply of the removed exhaust gas.

(2) In the above (1), either on the upstream side of the adsorption device or the upstream side of the biological deodorization device, or on the upstream side of the adsorption device and the upstream side of the biological deodorization device Each of these is provided with a gas temperature adjusting device for adjusting the exhaust gas temperature.

(3) Further, in the above (1) or (2), the adsorbing device includes a removable adsorbent cartridge having a plurality of flat adsorbent packed layers arranged at predetermined intervals. In the adsorbent cartridge, an exhaust gas flow is formed such that the exhaust gas supplied to one side surface of the adsorbent packed bed passes through the adsorbent packed bed toward the other side surface. The exhaust gas supplied to the adsorbent cartridge is distributed and flows to the plurality of adsorbent packed layers.

(4) Moreover, in the device according to any one of the above (1) to (3), the biological deodorization device includes a plurality of carrier packed layers filled with a carrier on which a living organism is immobilized, arranged at a predetermined interval. An exhaust gas flow is formed so that the exhaust gas supplied to one side surface of the carrier packed bed passes through the carrier packed layer toward the other side surface, and between the adjacent carrier packed layers, A separator for separating the exhaust gas flowing into the carrier packed bed from the exhaust gas flowing out from the other carrier packed bed is provided, and the exhaust gas supplied to the biological deodorizing device is distributed to the plurality of carrier packed beds and flows It is characterized by being.

(5) The deodorization method according to the present invention is a deodorization method for exhaust gas containing a volatile organic compound, and includes an adsorption step of adsorbing and removing an aromatic compound in the exhaust gas with an adsorbent, and an aromatic compound by the adsorption step. And a biological deodorization step of biodegrading the remaining volatile organic compound by receiving the supply of the exhaust gas adsorbed and removed.

(6) Further, in the above (5), a gas temperature adjusting step for adjusting the exhaust gas temperature is provided before the adsorption step and / or before the biological deodorization step.

In the present invention, in order to deodorize exhaust gas containing a volatile organic compound, an adsorption device is provided in the first stage, and the adsorption device compares the boiling point of the volatile organic compound having a large molecular weight from the exhaust gas. High-quality aromatic compounds are selectively adsorbed and removed to reduce the removal of aromatic compounds that are not suitable for biodegradation treatment from the exhaust gas, so that the biodegradation treatment can be carried out in a stable gas state. Biodegradation and removal of volatile organic compounds remaining in the deodorizer, that is, volatile organic compounds with a low molecular weight and a relatively low boiling point, remove various types of volatile organic compounds in exhaust gas with high efficiency. can do.
As described above, according to the present invention, various types of volatile organic compounds can be removed from exhaust gas containing volatile organic compounds with high efficiency, and the deodorizing apparatus and deodorizing device with low operating cost and low environmental load. A method can be provided.

It is explanatory drawing of the deodorizing apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the deodorizing agent cartridge used for the adsorption tower of the deodorizing apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the adsorption tower used for the deodorizing apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the other aspect of the adsorption tower used for the deodorizing apparatus which concerns on one embodiment of this invention. It is arrow AA figure of FIG. It is explanatory drawing of the biological deodorizing apparatus in the deodorizing apparatus which concerns on one embodiment of this invention. It is explanatory drawing of the deodorizing apparatus which concerns on other embodiment of this invention. It is explanatory drawing of the waste gas processing flow in one Example of this invention.

[Embodiment 1]
FIG. 1 is an explanatory view for explaining a deodorizing apparatus according to an embodiment of the present invention. The deodorization apparatus according to the present embodiment includes an adsorption tower 5 provided on the downstream side of the prefilter 3 provided in the exhaust gas line of the VOC gas generation source 1, and adsorbs and removes aromatic compounds in the exhaust gas. A biological deodorizing device 7 is provided on the downstream side to biodegrade the remaining volatile organic compounds upon supply of exhaust gas from which aromatic compounds have been adsorbed and removed. The exhaust gas obtained by biodegrading the volatile organic compound by the biological deodorizing device 7 is released to the atmosphere through the chimney 9.
Hereinafter, each apparatus which comprises a deodorizing apparatus is demonstrated in detail.

<Adsorption tower>
The adsorption tower 5 is provided with a packed bed of an adsorbent such as activated carbon. As a method of providing the packed bed, a mode in which the adsorbent is filled as it is in the adsorbing tower 5 is possible, but an adsorbent layer 13 formed by filling a removable adsorbent cartridge 11 as shown in FIG. 2 with the adsorbent. The multi-stage adsorbent cartridges 11 may be installed in the adsorption tower 5 as shown in FIG.

Gas inlets 15 and lids 17 are alternately provided on the upstream end surface of the adsorbent cartridge 11. Further, on the downstream end surface of the adsorbent cartridge 11, a lid portion 17 is provided at a portion corresponding to the gas inlet 15 on the upstream end surface, and a gas outlet 19 is provided at a portion corresponding to the lid portion 17 on the upstream end surface. It has been.
Further, in the adsorbent cartridge 11, as shown in FIG. 2, a plurality of flat adsorbent layers 13 are arranged substantially in parallel at a predetermined interval, and one of the adsorbent layers 13 is disposed through the gas inlet 15. A gas flow is formed such that the gas supplied to the side surface of the gas passes through the adsorbent layer 13 and escapes to the other side surface, and the gas sent to the adsorbent cartridge 11 is a plurality of adsorbent layers 13. Then, it is distributed and removed by adsorption.

Since the adsorbent cartridge 11 shown in FIG. 2 has a structure in which the exhaust gas and the adsorbent layer 13 are in contact with each other in a side flow manner, the area of the adsorbent layer 13 in contact with the gas can be increased. The area is small and economical. Moreover, since the adsorbent layer 13 is usually very thin, about several centimeters, the pressure loss can be reduced, and the blower is downsized and economical.
Further, since the adsorbent layer 13 is arranged substantially parallel to each other and symmetrical with respect to the surface, and the adsorbent is compactly packed so that no gap is formed between the adsorbent and the lid portion 17, high adsorbing performance is exhibited. In order to achieve this, the gas flow, which is essential, can be made uniform, a short gas pass (blow-off) is prevented, the contact efficiency between the adsorbent layer 13 and the gas is high, and high performance is exhibited during adsorption.
Furthermore, since it has a cartridge structure, it is easy to attach and detach the cartridge from the adsorption tower 5, and maintenance such as replacement of the adsorbent and inspection in the apparatus can be easily performed.

  In addition, if the size per 111 adsorbent cartridges becomes large, the detachment workability from the adsorption tower 5 at the time of maintenance deteriorates. For example, a large amount of gas such as tens of thousands to hundreds of thousands m3 / h is processed. In this case, it is preferable to use a plurality of adsorbent cartridges 11 arranged in parallel in the adsorption tower and installed in a plurality of stages in series. In the example shown in FIG. 5 which is a cross-sectional view taken along the line AA in FIGS. 4 and 4, an example is shown in which four adsorbent cartridges 11 are arranged in parallel and installed in two stages in series. Thus, by using the adsorbent cartridge 11, the arrangement of the adsorbent cartridges 11 can be combined in parallel and in series according to the use conditions, and can be used in an optimal arrangement.

<Biological deodorization device>
The biological deodorization apparatus 7 is provided with a carrier packed layer 21 of a carrier on which microorganisms are immobilized. FIG. 6 is an explanatory view for explaining the arrangement structure of the carrier packed layer 21.
In the carrier packed layer 21, a plurality (three in this example) of carrier packed layers 21 are arranged in parallel in the vertical direction at a predetermined interval. An exhaust gas inlet 23 is provided on one side of the carrier packed bed 21, and the exhaust gas flowing in from the exhaust gas inlet 23 is supplied to one side (upper side in the figure) of the carrier packed bed 21, and the other side ( An exhaust gas flow that passes through the carrier packed bed 21 toward the lower surface is formed. The exhaust gas that has passed through the carrier packed bed 21 is guided to the exhaust gas outlet 27 side and discharged by a partition wall 25 that forms a partition with the exhaust gas flow path of the adjacent carrier packed bed 21. The partition wall 25 corresponds to the separator of the present invention.
The biological deodorization apparatus 7 is provided with an exhaust gas inlet 23 for each carrier packed bed 21 in order to distribute and supply the exhaust gas to each carrier packed bed 21.
In FIG. 6, the exhaust gas flow is formed so as to pass through the carrier packed layer 21 from the upper surface side to the lower surface of the carrier packed layer 21, but the flow direction of the exhaust gas with respect to the carrier packed layer 21 is upside down (from the lower surface side to the upper surface). It is also possible to change the arrangement of the partition walls 25.

  By making the biological deodorization apparatus 7 as described above, the problems that the conventional facilities in the carrier-filled biological deodorization apparatus 7 have become larger and the installation area becomes larger can be solved. The equipment can be made compact. Each of the plurality of carrier packed layers 21 can be formed into a removable cartridge type, and the state of deterioration of the carrier packed layer 21, for example, the pressure loss for each carrier packed layer 21 is monitored, and the pressure loss is abnormal. When seen, only the carrier-filled layer 21 in which an abnormality has occurred can be replaced, and maintenance is facilitated.

  Next, a deodorizing method using the deodorizing apparatus configured as described above will be described. The exhaust gas discharged from the VOC generation source is introduced into the adsorption tower 5 after dust and mist in the exhaust gas are removed by the prefilter 3. In the adsorption tower 5, among the VOCs, high-boiling and high-molecular-weight VOCs that are easily adsorbed, mainly aromatic compounds, are adsorbed and removed. Among VOCs, low boiling point and low molecular weight VOCs such as formaldehyde are not removed by adsorption and are discharged from the adsorption tower 5 while remaining in the exhaust gas. The gas discharged from the adsorption tower 5 is introduced into the biological deodorization device 7, and the VOC remaining in the exhaust gas is biodegraded and removed.

[Embodiment 2]
FIG. 7 is an explanatory view for explaining a deodorizing apparatus according to another embodiment of the present invention. 7, the same components as those in FIG. 1 are denoted by the same reference numerals.
In the deodorizing apparatus of the present embodiment, a first temperature control tower 29 that adjusts the temperature of exhaust gas supplied to the adsorption tower 5 is provided upstream of the adsorption tower 5, and the biological deodorization apparatus 7 is provided upstream of the biological deodorization apparatus 7. A second temperature control tower 31 for adjusting the temperature of the exhaust gas to be supplied is provided.

The reason why the temperature control tower is provided is as follows.
The exhaust gas containing VOC differs greatly in the temperature discharged | emitted by the generation source. For example, the VOC-containing exhaust gas discharged from the printing process is often at a temperature close to room temperature, but the exhaust gas discharged from the printing process after printing may be in the temperature range of hundreds of degrees Celsius to two hundreds of degrees Celsius. Many. When deodorizing a relatively high temperature gas such as a gas discharged from the printing process after printing, the exhaust gas temperature is first lowered to a temperature at which the adsorption removal performance in the adsorption tower 5 is sufficiently exhibited. There is a need. For this reason, the first temperature control tower 29 is provided on the upstream side of the adsorption tower 5.

  The exhaust gas introduced into the biological deodorization apparatus 7 needs to be at a temperature of 40 ° C. or lower so as not to inhibit the activity of microorganisms. Therefore, when the exhaust gas temperature at the outlet of the adsorption tower is 40 ° C. or higher, the exhaust gas temperature on the upstream side of the biological deodorization device 7 needs to be lowered. For this purpose, the second temperature control tower 31 is provided.

  In the deodorization apparatus in the present embodiment configured as described above, the exhaust gas discharged from the VOC generation source is removed from the first temperature control tower 29 after the dust, mist, etc. in the exhaust gas are removed by the prefilter 3. The exhaust gas temperature is adjusted to a predetermined temperature and then introduced into the adsorption tower 5. In the adsorption tower 5, among the VOCs, high-boiling and high-molecular-weight VOCs that are easily adsorbed, mainly aromatic compounds, are adsorbed and removed. The exhaust gas exiting the adsorption tower 5 is introduced into the second temperature control tower 31 and the temperature is adjusted to 40 ° C. or lower. The exhaust gas that has exited the second temperature control tower 31 is introduced into the biological deodorization apparatus 7, and low boiling point, low molecular weight VOCs such as formaldehyde remaining in the exhaust gas are biodegraded and removed.

FIG. 8 is an explanatory view of an embodiment of the present invention, and is an explanatory view showing a process of treating exhaust gas containing VOC discharged from the paint baking process by the deodorizing apparatus of the present invention.
Various VOCs are contained in the exhaust gas discharged from the paint baking process.
In FIG. 8, the same parts as those in FIG. In addition, both the 1st cooling tower 33 and the 2nd cooling tower 35 are comprised as an indirect cooling tower which reduces exhaust gas temperature by heat exchange with the refrigerant | coolant supplied from a cooler.

  The VOC-containing exhaust gas discharged at about 160 ° C. from the paint baking process is introduced into the pre-filter 3 and after removing other gas components such as dust and mist contained in the exhaust gas, be introduced. In the first indirect cooling tower, the exhaust gas is cooled to about 80 ° C. to 90 ° C. by heat exchange with the refrigerant supplied from the cooler. Thus, by cooling to about 80 ° C. to 90 ° C., the adsorption efficiency of the VOC component by the adsorbent such as activated carbon packed in the adsorption tower 5 can be improved. Even with benzene having the simplest structure and the lowest boiling point of an aromatic compound, it is possible to maintain the adsorption efficiency by activated carbon at a high level by cooling to this temperature range. Further, cooling to a temperature lower than 80 ° C. is not preferable because the adsorption performance of the adsorbent such as activated carbon is lowered due to the influence of condensed water.

The exhaust gas exiting the adsorption tower 5 is introduced into the second indirect cooling tower before being introduced into the biological deodorization apparatus 7. In this second indirect cooling tower, the exhaust gas is cooled to 30 ° C. to 40 ° C., which is a temperature suitable for biological treatment, by heat exchange with the refrigerant supplied from the cooler. In the second indirect cooling tower, moisture contained in the exhaust gas is condensed to generate condensed water. The whole amount of the condensed water accumulated in the lower part of the cooling tower is used as make-up water for the biological deodorization apparatus 7. If this condensed water alone does not reach the amount of water as makeup water for the biological deodorization device 7, makeup water is newly introduced from the outside as necessary.
The exhaust gas cooled to 30 ° C. to 40 ° C. in the indirect cooling tower is introduced into the soil packed bed of the biological immobilization carrier in the biological deodorization apparatus 7 and remains in the exhaust gas without being removed by the adsorption tower 5. The VOC component is captured by being adsorbed or dissolved in soil, moisture in the soil, etc., and further decomposed and removed by microorganisms.

  In order to confirm the effect of the present example, the exhaust gas properties were measured at each location of the exhaust gas generation source, the adsorption tower outlet, and the biological deodorization apparatus outlet. The results are shown in Table 1.

  As can be seen from Table 1, aromatic compounds such as xylene can be adsorbed and removed by the adsorption tower, low molecular weight VOCs such as formaldehyde can be decomposed and removed by the biological deodorization device, and the total VOC can be greatly removed. I was able to confirm that it was possible.

  The present invention can be used in the industrial field for removing harmful substances in gas.

DESCRIPTION OF SYMBOLS 1 VOC gas generation source 3 Pre filter 5 Adsorption tower 7 Biological deodorizing device 9 Chimney 11 Adsorbent cartridge 13 Adsorbent layer 15 Gas inlet 17 Lid part 19 Gas outlet 21 Carrier filling layer 23 Exhaust gas inlet 25 Partition 27 Exhaust gas outlet 29 1st temperature Control tower 31 Second temperature control tower 33 First cooling tower 35 Second cooling tower

Claims (6)

A deodorizing apparatus for exhaust gas containing volatile organic compounds,
An adsorption device that adsorbs and removes aromatic compounds in the exhaust gas; and a biological deodorization device that biodegrades volatile organic compounds remaining by receiving supply of exhaust gas from which aromatic compounds are adsorbed and removed from the adsorption device. Deodorizing device characterized by.   A gas temperature control device for adjusting the exhaust gas temperature is provided on either the upstream side of the adsorption device or the upstream side of the biological deodorization device, or on the upstream side of the adsorption device and the upstream side of the biological deodorization device. The deodorizing apparatus according to claim 1.   The adsorbing device has a removable adsorbent cartridge having a plurality of flat adsorbent packed layers arranged at predetermined intervals, and one side surface of the adsorbent packed layer in the adsorbent cartridge. An exhaust gas flow is formed so that the exhaust gas supplied to the side passes through the adsorbent packed layer toward the other side surface, and the exhaust gas supplied to the adsorbent cartridge is formed in the plurality of adsorbent packed layers. It is comprised so that it may distribute and flow, The deodorizing apparatus of Claim 1 or 2 characterized by the above-mentioned.   In the biological deodorization apparatus, a plurality of carrier packed layers filled with a carrier immobilizing a living organism are arranged at a predetermined interval, and the exhaust gas supplied to one side surface of the carrier packed layer is directed toward the other side surface. An exhaust gas flow passing through the carrier packed bed is formed, and the exhaust gas flowing into one of the carrier packed beds and the exhaust gas flowing out of the other carrier packed bed are separated between the adjacent carrier packed beds. The deodorization according to any one of claims 1 to 3, wherein a separator is provided, and the exhaust gas supplied to the biological deodorization device is configured to flow while being distributed to a plurality of carrier packed beds. apparatus. A method for deodorizing exhaust gas containing a volatile organic compound,
An adsorption process for adsorbing and removing aromatic compounds in the exhaust gas with an adsorbent; and a biological deodorizing process for biodegrading remaining volatile organic compounds upon receipt of exhaust gas from which aromatic compounds have been adsorbed and removed by the adsorption process A deodorizing method comprising:   6. The deodorizing method according to claim 5, further comprising a gas temperature adjusting step for adjusting an exhaust gas temperature before the adsorption step and / or before the biological deodorizing step.

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