JP2004057900A - Method and equipment for treating pcb-containing gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of treating a PCG-containing exhaust gas which can surely remove PCB by surely grasping the PCB adsorption condition of used active carbon when the PCB containing exhaust gas and lower boiling point organic components produced in a facility for treating substances polluted with PCB etc. is treated, and an equipment for treating the PCB-containing gas. <P>SOLUTION: The method of treating the PCB-containing exhaust gas, in which the exhaust gas containing PCB and the lower boiling point organic components is adsorption-treated by at least two adsorption layers, is characterized in that an adsorption process in which the exhaust gas is introduced and adsorption-treated and a regeneration for recovering an adsorption function are implemented alternately every prescribed change-over time for the adsorption layer. In the method for treating the PCB-containing exhaust gas, the concentration of the lower boiling point organic components is measured on the exhaust gas after adsorption treatment. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating PCB-containing exhaust gas discharged from a PCB contaminant treatment facility or the like and containing PCB and a low-boiling organic component, and a device for treating PCB-containing exhaust gas.
[0002]
[Prior art]
In order to detoxify PCB-contaminated equipment such as capacitors and transformers using polychlorinated biphenyls (also simply referred to as PCB in the present invention), pretreatment such as oil removal, cutting, and dismantling was performed from the PCB contaminated material. Thereafter, it is necessary to repeatedly perform washing with an organic solvent.
[0003]
In such a process, it is necessary to suction and remove dust generated during pretreatment of PCB contaminants and volatile components of the solvent generated during cleaning with the solvent. Further, the exhaust gas sucked from various places in the facility in such a manner may contain a very small amount of PCB. Therefore, it is desirable that such an exhaust gas be completely adsorbed by a plurality of activated carbon adsorption towers to remove even a trace amount of PCB without fail, and then discharged outside the facility.
[0004]
However, the exhaust gas generated in the PCB contaminant treatment facility as described above has a feature that an extremely large amount of cleaning solvent is contained in comparison with the amount of PCB. Therefore, conventionally, as for the activated carbon adsorption tower, two or more adsorption towers which can be used alternately are installed, and the other activated carbon is treated with a regeneration gas such as steam while the other activated carbon is being adsorbed. There has been studied a method of recovering the adsorption capacity and then switching and using these two adsorption towers after the temperature of the activated carbon has dropped.
[0005]
When activated carbon is used repeatedly, the activated carbon gradually deteriorates and becomes finer, so that the pressure loss of the activated carbon adsorption tower increases.In general, the replacement time of the activated carbon is determined based on the increase in the pressure loss. It seems that a method of judging will be adopted.
[0006]
However, PCB has a property that it is not easily desorbed from activated carbon by steam or the like like a solvent, and therefore, there is a possibility that the adsorption capacity of the PCB is reduced more quickly than the activated carbon is deteriorated. Therefore, as for the activated carbon used for the adsorption treatment of the PCB-containing exhaust gas as described above, the conventional method of determining the replacement time based on the increase in the pressure loss may cause the PCB to break through the adsorbed layer. The exhaust gas treatment method used in conjunction with the pollutant treatment equipment is not perfect.
In addition, when the official analysis method is used as a method for detecting a PCB, a long time is required, and when online analysis using a sensor or the like is used, there is a problem that the apparatus becomes very expensive.
[0007]
[Problems to be solved by the invention]
Therefore, the present invention provides a method for treating the exhaust gas containing PCBs and low-boiling organic components generated in a PCB contaminant treatment facility or the like, in which the PCB adsorption state of the activated carbon to be used is accurately grasped, and the PCBs are more reliably produced. An object of the present invention is to provide a method and an apparatus for treating a PCB-containing exhaust gas that can be removed.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is a method for treating a PCB-containing exhaust gas, wherein the exhaust gas containing PCB and a low-boiling organic component is subjected to adsorption treatment by using two or more adsorption layers. Performing the adsorption step and the regeneration step for restoring the adsorption capacity alternately at predetermined switching times for the adsorption layer, and further measuring the concentration of the low-boiling organic component in the exhaust gas after the adsorption treatment. And a method for treating PCB-containing exhaust gas.
In the present invention, the organic component having a low boiling point generally refers to an organic solvent that is used for cleaning to remove PCB from PCB contaminants and has a lower boiling point than PCB. In this specification, it is simply referred to as a solvent.
Further, in the present invention, the detection of a low-boiling organic component refers to a case where the measured low-boiling organic component concentration is equal to or higher than a predetermined value.
[0009]
According to the present invention, when a low-boiling organic component is detected within a predetermined switching time, for example, 8 hours, a considerable amount of PCB is accumulated in the adsorbing layer in use (the breakthrough time of PCB). Is approaching), and can be used as a criterion for a safer replacement time, which is different from the conventional method of determining the replacement time due to the increase in pressure loss.
[0010]
In a preferred embodiment of the present invention, in the method for treating a PCB-containing exhaust gas, the adsorption layer is replaced when a low-boiling organic component is detected by measurement. Alternatively, in the method for treating a PCB-containing exhaust gas, switching between the adsorption step and the regeneration step is performed when a low-boiling organic component is detected by measurement.
[0011]
If the adsorption layer is replaced by detecting the low-boiling organic component, it is possible not only to prevent the low-boiling organic component from leaking, but also to reliably prevent the PCB from leaking.
In addition, by switching between the adsorption step and the regeneration step when a low-boiling organic component is detected, it is necessary to effectively use the adsorption layer while reliably preventing PCB leakage, and to replace the adsorption layer. Time can be secured.
[0012]
Further, the present invention is a method for treating a PCB-containing exhaust gas in which an exhaust gas containing PCB and a low-boiling organic component is adsorbed by two or more adsorption layers, wherein the PCB exhaust gas has two or more different PCB concentrations. At the same time as introducing the exhaust gas, the exhaust gas having a low PCB concentration is concentrated and subjected to an adsorption treatment together with the exhaust gas having a high PCB concentration, and the adsorption step and the regeneration step for restoring the adsorption capacity are performed at predetermined switching times for the adsorption layer. The present invention provides a method for treating PCB-containing exhaust gas, wherein the method is performed alternately, and the concentration of the low-boiling organic component is measured in the exhaust gas after the adsorption treatment.
[0013]
According to such a method for treating a PCB-containing exhaust gas, in addition to the above-described effects, a unique effect that a large amount of exhaust gas having a low PCB concentration and a small amount of exhaust gas having a high PCB concentration can be efficiently treated is exhibited. .
[0014]
Further, the present invention is a treatment apparatus for a PCB-containing exhaust gas for adsorbing an exhaust gas containing PCB and a low-boiling organic component, wherein the adsorption step comprises introducing the exhaust gas and adsorbing the exhaust gas; And a regeneration step for alternately performing a regeneration step for every predetermined switching time, and a sensor for measuring the concentration of low-boiling organic components in the exhaust gas after the adsorption treatment. To provide an apparatus for treating PCB-containing exhaust gas.
[0015]
According to the apparatus for treating a PCB-containing exhaust gas having such a configuration, the PCB adsorption state of the adsorption layer can be estimated from the measured low-boiling-point organic component concentration, so that the adsorption layer can be used without directly measuring the PCB concentration. This can be detected in advance before the PCB breaks through the PCB, and the timing for replacing the activated carbon can be properly determined, so that leakage of the PCB can be more reliably prevented.
[0016]
The present invention also relates to a device for treating PCB-containing exhaust gas for adsorbing exhaust gas containing PCB and low-boiling organic components, wherein two or more types of exhaust gas having different PCB concentrations are introduced as the exhaust gas. A honeycomb rotor for concentrating exhaust gas having a low concentration, two or more adsorption layers for introducing the exhaust gas having a high PCB concentration and the concentrated gas, and alternately performing an adsorption step and a regeneration step at predetermined switching times; Provided is a device for treating a PCB-containing exhaust gas, which is provided with a sensor for measuring the concentration of low-boiling organic components in the exhaust gas after the adsorption treatment.
[0017]
According to such a treatment device for a PCB-containing exhaust gas, in addition to the above-described effects, a specific effect that a large amount of the exhaust gas having a low PCB concentration and a small amount of the exhaust gas having a high PCB concentration can be efficiently treated is exhibited. .
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
FIG. 1 is a flow chart showing an embodiment of the apparatus for treating PCB-containing exhaust gas according to the present invention. As shown in FIG. 1, a PCB-containing exhaust gas treatment apparatus 1 according to the present embodiment is recovered from a PCB contaminant treatment facility and used for cleaning PCBs and PCBs and low-boiling organic components (hereinafter simply referred to as “solvents”). ) Is introduced and treated.
[0020]
Exhaust gas X is used, for example, in a pre-stage of a PCB contaminant treatment facility (not shown) for controlling negative pressure from a pre-treatment process such as an oil removal process, a cutting process, a dismantling process, or a pre-cleaning process of the PCB contaminant. Exhaust gas generated by suction and discharged together with a relatively large amount of air.
On the other hand, the exhaust gas Y is an exhaust gas generated from a cleaning process in which PCB contaminants are decomposed into containers, insulators, other metal parts, and the like, and then washed with a solvent. The exhaust gas Y has a relatively high concentration of PCB and low-boiling organic components. Is included.
[0021]
As the solvent, a hydrocarbon solvent or an organic chlorine solvent is generally used. Among them, normal paraffin is preferred as the hydrocarbon solvent, and those having 9 to 12 carbon atoms are particularly preferably used. As the organic chlorine-based solvent, perchlorethylene is preferable.
[0022]
As shown in FIG. 1, the exhaust gas X containing PCB is configured to be discharged as a clean gas through the pre-adsorption layer 21 and the honeycomb rotor 22. Then, a high-temperature (200 to 400 ° C.) inert gas is introduced into the honeycomb rotor 22, and the adsorbed PCB is desorbed into a concentrated gas Z, which is processed together with an exhaust gas Y containing PCB and a solvent. Have been.
[0023]
The steam components (PCB and solvent) of the exhaust gas Y and the concentrated gas Z are cooled by the steam condenser 11 to be condensed to reduce the amounts of PCB and solvent in the gas, and then used alternately. It is configured to be introduced into one of the side-by-side adsorption layers 12 (12a in FIG. 1), subjected to adsorption treatment by an adsorbent, and then discharged through the final adsorption layer 13 as a clean gas.
In the exhaust gas path from the adsorption layer 12 to the final adsorption layer 13, a gas monitor 14 for detecting the content of a solvent (low-boiling organic component) is provided. It is configured to transmit.
[0024]
Further, the apparatus for treating PCB-containing exhaust gas of the present embodiment is provided with a regeneration processing means for regenerating the adsorbent on the unused side of the adjacent adsorption layer 12. Specifically, the regenerating means is a high-temperature (100 to 150 ° C.) steam or high-temperature (100 to 150 ° C.) (400 ° C.), an inert gas is supplied to desorb the solvent from the activated carbon, and the mixed vapor after desorption is condensed. Then, the separated steam is allowed to stand still in a solvent and water by a separation tank 31. It is configured to discharge through the treatment adsorption layer 32.
[0025]
Further, with respect to the solvent adsorbed on the post-treatment adsorption layer 32, the activated carbon can be similarly regenerated by supplying high-temperature steam or high-temperature inert gas to the post-treatment adsorption layer to desorb the solvent. It is configured to be.
[0026]
As the adsorbent filled in the adsorbent layer 12, a material having high selective adsorption to PCB is preferable. For example, a pore diameter of 11 to 22 °, a specific surface area of 1000 m ² / g or more, and a packing density of 0.38 to 0.5 g / Cc, hardness of 96% or more, moisture of 3% or less, and activated carbon having a particle size of 4 to 6 mesh of 95% or more can be suitably used.
[0027]
Further, in the regeneration process of the adsorbent, the temperature of the adsorbent rises to 100 ° C. or higher due to the supplied steam or inert gas. Need to be reduced to Therefore, it is preferable that the amount of the adsorbent to be filled in the adsorption layer 12 is such that the PCB and the solvent can be sufficiently adsorbed for the total time of the regeneration processing time and the cooling time in the regeneration step.
[0028]
The gas monitor 14 is not particularly limited as long as it can detect a solvent (low-boiling organic component). For example, a VOC (volatile organic compound) monitor can be suitably used.
[0029]
The pre-adsorption layer 21, the final adsorption layer 13, and the post-treatment adsorption layer 32 are also filled with an adsorbent such as activated carbon, respectively. The material and the post-treatment adsorption layer 32 are filled with an adsorbent for water treatment.
[0030]
The honeycomb rotor 22 has a columnar adsorbent (for example, activated carbon) having a honeycomb-shaped fine flow path supported rotatably in the circumferential direction, and a region where the adsorbent rotates to adsorb the exhaust gas, and a region where the adsorbent is adsorbed. It is configured to sequentially pass through a region where desorption is performed by an active gas. The inert gas discharged from the desorption region is configured to contain an organic substance such as PCB in a higher concentration than the processing exhaust gas, that is, to reduce the flow rate of the gas to be processed.
[0031]
In operation of the exhaust gas treatment apparatus having such a configuration, the adsorbent layers 12 arranged side by side are operated such that the adsorption step and the regeneration step are automatically switched, for example, every eight hours. That is, while the adsorption process is performed by the one adsorption layer 12a, the other adsorption layer 12b is cooled after the desorption process by steam, and the adsorption capacity is regenerated. Then, when the set switching time (for example, 8 hours) is reached, one of the adsorption layers 12a that has completed the adsorption step and the other adsorption layer 12b that has completed the regeneration step are automatically processed by changing the gas path. The process is switched, and the regeneration process is started in one adsorption layer 12a, and the adsorption process is started in the other adsorption layer 12b.
[0032]
While the adsorbent has a sufficient adsorption capacity, the solvent is not detected by the gas monitor 14 within a preset switching time (for example, 8 hours). However, when the adsorption step and the regeneration step are repeated as described above, the PCB is gradually accumulated in the adsorbent in the adsorbent layer 12, and the adsorbing ability of the adsorbent gradually decreases.
[0033]
After a certain period of time from the start of the exhaust gas treatment, the PCB is adsorbed to such an extent that the low-boiling organic components to be adsorbed cannot be completely adsorbed. It is presumed that the breakthrough time by the solvent becomes shorter.
If the adsorbent breaks through the solvent within the switching time, the solvent is contained in the exhaust gas that has passed through the adsorbing layer 12, and this can be immediately detected by the gas monitor 14. .
[0034]
The detection of such a low-boiling organic component also indicates that the breakthrough time of the PCB is approaching, and the operation can be performed while monitoring the PCB adsorption state of the adsorbent in real time.
[0035]
That is, in the exhaust gas treatment according to the present embodiment, it is necessary to determine the replacement time of the adsorbent in the adsorbent layer not only from the viewpoint of the conventional deterioration of the adsorbent but also from the viewpoint of preventing PCB leakage. Can be.
[0036]
Therefore, when a low-boiling organic component is detected by the gas monitor 14, it is preferable to replace the adsorption layer from the viewpoint of preventing PCB leakage. Need to secure. Therefore, when a low-boiling organic component is detected by the gas monitor 14, this time may be set as the switching time between the adsorption step and the regeneration step, and the processing step may be switched before the set switching time. Thereby, while reliably preventing leakage of the PCB, time for replacing the adsorbing layer can be secured, and the adsorbing layer can be effectively used.
[0037]
Further, in the present embodiment, since the final adsorption layer 13 is provided at the subsequent stage of the adsorption layer 12 which is used alternately, not only the leakage of the PCB and the low-boiling organic components can be reliably prevented during the normal operation, but also Even in the case of such replacement, leakage of PCB or the like can be reliably prevented.
[0038]
Furthermore, in the present embodiment, the extremely low-concentration exhaust gas discharged from the PCB contaminant treatment facility is also concentrated by the honeycomb rotor and is adsorbed together with the other exhaust gas, so that the treatment of the exhaust gas can be performed compactly and at low cost. There is an effect that can be performed.
[0039]
Further, the solvent separated in the interface separation tank 31 of the above embodiment can be returned to the PCB contaminant treatment facility and processed together with a solvent for cleaning PCB contaminants.
On the other hand, the water recovered through the post-treatment adsorption layer 32 can be discharged to the outside of the system, but can be used as boiler water or the like to form a closed system.
[0040]
【The invention's effect】
ADVANTAGE OF THE INVENTION As mentioned above, according to the PCB-containing exhaust gas treatment method and treatment equipment of the present invention, the PCB adsorption state of the adsorption layer can be accurately grasped, and the exhaust gas treatment method and exhaust gas capable of more reliably removing PCB can be obtained. A processing device can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic flow chart showing a facility for treating PCB-containing exhaust gas according to the present invention.
[Explanation of symbols]
1 ... PCB-containing exhaust gas treatment equipment, 11 ... Steam condenser, 12 ... Adsorption layer,
13: final adsorption layer, 14: gas monitor, 15: computer,
21: Pre-adsorption layer, 22: Honeycomb rotor, 31: Interface separation tank,
32: post-treatment adsorption layer, X: exhaust gas generated from the pre-treatment step,
Y: exhaust gas generated from the washing process, Z: concentrated exhaust gas

Claims (6)

A method for treating a PCB-containing exhaust gas, wherein the exhaust gas containing PCB and a low-boiling organic component is subjected to adsorption treatment by two or more adsorption layers,
The adsorption step of introducing the exhaust gas to perform the adsorption treatment and the regeneration step for restoring the adsorption capacity are performed alternately at predetermined switching times for the adsorption layer, and further, the exhaust gas after the adsorption treatment has the low boiling point. A method for treating PCB-containing exhaust gas, comprising measuring the concentration of an organic component. The method for treating a PCB-containing exhaust gas according to claim 1, wherein the adsorption layer is replaced when a low-boiling organic component is detected by the measurement. 2. The method for treating a PCB-containing exhaust gas according to claim 1, wherein switching between the adsorption step and the regeneration step is performed when a low-boiling organic component is detected by the measurement. A method for treating a PCB-containing exhaust gas, wherein the exhaust gas containing PCB and a low-boiling organic component is subjected to adsorption treatment by two or more adsorption layers,
Introducing two or more types of exhaust gas having different PCB concentrations as the PCB exhaust gas, concentrating the exhaust gas having a low PCB concentration, performing adsorption treatment together with the exhaust gas having a high PCB concentration, and performing the adsorption step and the regeneration step for restoring the adsorption ability. And alternately performing a predetermined switching time for the adsorption layer, and measuring the concentration of the low-boiling organic component in the exhaust gas after the adsorption treatment. A device for treating a PCB-containing exhaust gas for adsorbing an exhaust gas containing PCB and a low-boiling organic component,
Two or more adsorption layers that alternately perform an adsorption step of introducing the exhaust gas to perform an adsorption treatment and a regeneration step for restoring the adsorption capacity at predetermined switching times;
An apparatus for treating a PCB-containing exhaust gas, comprising a sensor for measuring the concentration of a low-boiling organic component in the exhaust gas after the adsorption treatment. A device for treating a PCB-containing exhaust gas for adsorbing an exhaust gas containing PCB and a low-boiling organic component,
Introducing two or more types of exhaust gas having different PCB concentrations as the exhaust gas,
A honeycomb rotor for concentrating exhaust gas with low PCB concentration,
Two or more adsorbent layers for introducing an exhaust gas having a high PCB concentration and the concentrated gas, and alternately performing an adsorption step and a regeneration step every predetermined switching time;
An apparatus for treating a PCB-containing exhaust gas, comprising a sensor for measuring the concentration of a low-boiling organic component in the exhaust gas after the adsorption treatment.

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