JPH08155253A - Control of concentration ratio in concentration type deodorizer - Google Patents

Abstract

PURPOSE: To control concentrating ratio of gas concn. of the heated air for regeneration by circulating a part of the heated air for regeneration fed into a regenerating zone from a cooling zone through a heating zone. CONSTITUTION: After air for cooling is passed through a cooling zone 4, it is heated to a specified temp. by means of a heater 6 and is introduced into a regenerating zone 3. The regenerated gas going out from the regenerating zone 3 is divided at the rear stage of a fan 8 and a part thereof is returned to the heater 6 and is circulated. It is possible thereby to increase the amt. of heated air for regeneration without being restricted by the concentrating ratio and a perfect regeneration is performed. In addition, the amt. of circulating air is adjusted by means of an air flow adjusting damper 10 arranged in a flow path between the cooling zone 4 and the heater 6 and an air flow adjusting damper 11 arranged in a branched path on the downstream of the fan 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a concentration ratio in a concentration type deodorizing device.

[0002]

2. Description of the Related Art Volatile organic compounds (VO
C) (hereinafter, referred to as VOC) treatment device includes combustion method, adsorption method, biological method, etc., but with respect to exhaust gas with low gas concentration and large air volume, these methods require equipment cost and operation cost. It is not often used because it becomes high. Generally, a method is adopted in which these exhaust gases are concentrated to reduce the amount of gas and the exhaust gas is burned.

A method which has been widely adopted as a method for concentrating exhaust gas having a low concentration and a large air volume has been that a VOC is once adsorbed on an adsorbent having a function of adsorbing VOC, for example, a honeycomb rotor carrying activated carbon or zeolite. It is adsorbed and desorbed with a small amount of heated air.

The mechanism of this concentration is shown in FIGS. FIG. 5 is a schematic perspective view of the concentration type deodorizing device, and FIG.
FIG. 3 is a schematic diagram of a concentration type deodorizing device. In FIG. 5, the honeycomb rotor 1, which is the structure of the concentrating device, is continuously rotated in the counterclockwise direction indicated by arrow A at a constant speed by the drive motor 5. The honeycomb rotor 1 is divided into an adsorption zone 2 for adsorbing VOCs, a regeneration zone 3 for desorbing the adsorbed VOCs to restore the adsorption ability of the honeycomb rotor, and a cooling zone 4 for cooling the honeycomb rotor heated in the regeneration zone. ing. In addition, each zone has a seal structure (not shown) to prevent gas leaks from occurring.
Is given.

The rotation of the honeycomb rotor portion causes the adsorption zone 2, the regeneration zone 3 and the cooling zone 4 to move continuously in this order. The target processing gas is passed through the adsorption zone in the direction indicated by the arrow B, and the VOC contained in this gas is adsorbed by the adsorbent arranged in the honeycomb rotor, becomes a clean (purified) gas, and is released to the atmosphere. To be done. The portion of the honeycomb rotor that has adsorbed the VOCs enters the regeneration zone, and in this regeneration zone, a small amount of the heating air heated by the heater 6 is passed through the portion of the honeycomb rotor, The VOCs adsorbed on the rotor are desorbed and become concentrated gas.

Since the honeycomb rotor is naturally heated when desorbing VOCs with heated air, the adsorption capacity of the adsorbent for adsorbing VOCs is greatly reduced. In order to restore the adsorption capacity, the part of the honeycomb rotor is cooled by passing atmospheric air in the next cooling zone and moves to the adsorption zone again.

Generally, the air for regeneration (desorption) and the air for cooling are used as a series of streams to recover waste heat. That is, the atmospheric air enters the cooling zone, where it receives the sensible heat accumulated in the honeycomb rotor to become warm air, enters the heater 6 as indicated by arrow C, and is required by the heater 6 for regeneration. It is heated to a certain temperature, enters the regeneration zone, and is taken out as a concentrated gas as shown by arrow D. The enriched gas containing VOCs desorbed in the regeneration zone is then processed by catalytic combustion or direct combustion methods.

[0008]

In the concentration phenomenon by the adsorbent, the adsorption is an exothermic phenomenon, and the regeneration (desorption) is caused.
Is an endothermic phenomenon. Therefore, the amount of heat required for regeneration is V
The amount of heat for desorption of OC and the amount of heat for heating the honeycomb rotor are required. However, the temperature of the heated air for regeneration is restricted by the heat-resistant temperature of the equipment (particularly the sealing material), and is also restricted by the deterioration of the gas components at high temperatures and the adverse effect on the adsorbent due to the polymerization reaction. Receive. Therefore, the minimum required temperature is desirable. At the same time, of course, the amount of regenerated heating air is naturally limited in terms of the concentration ratio. Therefore, a sufficient amount of heat required to completely regenerate the honeycomb rotor that has adsorbed the gas component must be given under the above-mentioned constraint condition.

Generally, the concentration ratio of the concentration type deodorizing device is 5
~ 15 times. Further, this concentration ratio is determined by the conditions of the target processing gas and the like. At the same time, if the concentration of the processing gas changes, the concentration of the concentrated gas also changes in proportion to the concentration of the processing gas. That is, one of the processing gas amount
The air determined to be / 5 to 1/15 is introduced into the cooling zone, and the honeycomb rotor heated in the regeneration zone is cooled in this cooling zone. After that, this is further heated to a predetermined temperature by the heater 6 and enters the regeneration zone, and the VOC adsorbed on the honeycomb rotor is desorbed to become a concentrated gas.

When the concentration ratio becomes high, the amount of heating air for regeneration becomes small, so that a sufficient amount of heat cannot be obtained and complete regeneration cannot be performed. That is, if a sufficient amount of heat is not applied, the regeneration is near the surface where the regenerated heated air is introduced, the regeneration on the downstream side is insufficient, and the adsorption function of the honeycomb rotor is not sufficiently restored. Moreover, if the temperature of the regenerated heating air is too high,
There is also a risk of deterioration of the components of the processing gas, polymerization, etc., which is not preferable for the honeycomb rotor and is also restricted by the heat resistant temperature of the apparatus.

In FIG. 6, reference numeral 8 is a reproducing fan, and reference numeral 9 is an air volume adjusting damper.

Therefore, an object of the present invention is to provide a control method for arbitrarily controlling the concentration ratio and a control method for controlling so as to maintain a constant gas concentration without being affected by a change in the concentration of the processing gas. .

[0013]

In order to achieve the above-mentioned object, the present invention provides a method for controlling a concentration ratio in a concentration type deodorizing device having a honeycomb rotor divided into an adsorption zone, a regeneration zone and a cooling zone, A method characterized by controlling the concentration ratio of the gas concentration of the heating air for regeneration by circulating a part of the heating air for regeneration supplied from the cooling zone to the regeneration zone through the heater. Is.

[0014]

EXAMPLES Next, examples of the present invention will be described.

Example 1 FIG. 1 is a schematic flow chart of Example 1 of the method of the present invention. In each of the following examples including the first example, members having the same functions and configurations as the members used in the conventional example are designated by the same reference numerals.

In FIG. 1, the cooling air is supplied to the cooling zone 4
After being passed through, it is heated to a predetermined temperature by the heater 6,
Enter playback zone 3. The regeneration gas that has exited the regeneration zone 6 is branched at the latter stage of the fan 8 and a part of it is returned to the heater 6 and circulated. This makes it possible to increase the amount of heating air for regeneration without being restricted by the concentration ratio, and complete regeneration is performed. The circulation air volume is adjusted by the air volume adjustment damper 10 arranged in the flow path between the cooling zone 4 and the heater 6 and the air volume adjustment damper 11 arranged in the branch path branched downstream of the fan 8. It

Example 2 FIG. 2 is a schematic flow chart of Example 2 of the method of the present invention. The method of the second embodiment is for controlling the gas concentration to an arbitrary value. As is clear from FIG. 2, the second embodiment is provided with a concentration detector 12 downstream of the regeneration zone 3, and the air volume adjustment damper 10 (disposed in the flow path between the cooling zone 4 and the heater 6) in the first embodiment. However, it is different from the first embodiment in that an automatic air volume adjustment damper 10 'is provided and the automatic air volume adjustment damper 10' is controlled according to the concentration detected by the concentration detector 12.

The set value of the concentration detector 12 is generally VOC.
It is selected to be 1/3 or less of the lower explosion limit, which is the upper limit of the gas combustion process. So that it will be this set value
By controlling the automatic air volume adjustment damper 10 ′, it becomes possible to completely regenerate the honeycomb rotor and simultaneously maintain the concentration of the concentrated gas at a high concentration and constant.

(Embodiment 3) When the concentration of the concentrated gas is kept constant as in the second embodiment, the concentration of the processing gas changes, and the amount of the concentration gas also changes accordingly. Therefore, when the cooling air is used as the regenerative heating air, the amount of the cooling air fluctuates and the air volume also decreases. As a result, sufficient cooling in the cooling zone becomes difficult, and the cooling effect decreases. FIG. 3 is a schematic flow chart of Example 3 of the method of the present invention for preventing the reduction of the cooling effect.
In this third embodiment, as is clear from FIG.
In addition to the above configuration, a cooling fan 13 and an air volume adjusting damper 14 are provided. As a result, the cooling fan 13 can take in a sufficient amount of air for cooling, and a part of the amount of air used for cooling (only the amount necessary for regeneration) can be automatically adjusted. To become heated air for regeneration, and the rest is released to the atmosphere. The amount of cooling air is adjusted by the air amount adjustment damper 14.

Next, in order to confirm the effect of the present invention, the conventional example and the present invention will be compared and examined. In the conventional concentration method (FIGS. 5 and 6), since the amount of heating air for regeneration is determined by the concentration ratio, a sufficient amount of heat cannot be obtained especially when the concentration ratio becomes high, and the honeycomb rotor that has adsorbed VOCs is completely It is not regenerated, and as a result, the adsorption efficiency is naturally lowered. For example, when the temperature of the heating air for regeneration is 160 ° C. and the concentration ratio increases, the amount of heating air for regeneration decreases and the outlet temperature of the regeneration zone decreases to about 40 ° C. Depending on the physical properties of the VOC, when the temperature of the regenerated air is 60 ° C or less, the desorption phenomenon is not expected so much, and the VOC remains without being desorbed on the downstream side of the regeneration zone of the honeycomb rotor. Loss of functionality.

FIG. 4 is a schematic diagram for explaining the adsorption capacity. FIG. 4a shows an adsorption, regeneration and cooling cycle with a sufficiently regenerated adsorption capacity, and FIG. 4b shows an adsorption, regeneration and cooling cycle with insufficient regeneration. In the case of FIG. 4a, the adsorption capacity has a margin and the adsorption efficiency is high. In the case of FIG. 4b, the regeneration efficiency is low and the adsorption capacity is insufficient,
Naturally, the adsorption efficiency becomes low. In particular, when a breakthrough region (d) is formed, the efficiency is extremely reduced. In FIG. 4, reference numeral (a) indicates the thickness of the honeycomb rotor, reference numeral (b) indicates the margin area of the honeycomb rotor, and reference numeral (c) indicates the effective thickness of the honeycomb rotor. Further, in FIG. 4, the hatched portion indicates the VOC adsorption area.

In the present invention, under the limited regeneration conditions, the temperature distribution in the thickness direction of the honeycomb rotor in the regeneration zone is made uniform, and the honeycomb rotor in the adsorption zone is always maintained in the state shown in FIG. 4a. It is what

(Experimental Example) Next, an experimental example for comparing the method of the present invention with the conventional method will be described. Attachment 1
Represents the result of this experiment. In Table 1, the conventional method is
The method shown in FIGS. 5 and 6 is used, the regeneration heating air circulation method is the method of Example 1 and Example 2 shown in FIGS. 1 and 2, and the regeneration gas concentration setting method is shown in FIG. The method of Example 3 shown in FIG. The details of the processing gas used in the experiment are as follows. Processing gas specifications Processing gas amount 1800 m ³ N / min Gas composition Toluene and xylene Gas concentration 50 to 200 ppm Gas temperature 30 ° C

As is clear from Table 1, even if the adsorption capacity of the honeycomb rotor is sufficient for the processing gas conditions, the conventional method does not give the energy required for regeneration to the honeycomb rotor and the regeneration is insufficient. Therefore, the adsorption efficiency decreases. In the regenerated heated air circulation method, since sufficient heat energy is applied to the honeycomb rotor, complete regeneration is possible and adsorption efficiency is improved. Therefore, the concentration of the processing gas at the outlet becomes low, and the concentration of the regeneration gas becomes slightly high. The regeneration gas concentration setting method, like the regeneration heating air circulation method,
The regeneration is complete and the adsorption efficiency is improved. The regeneration gas concentration is 2,500 ppm, which is the set concentration, and the regeneration gas amount is 3
It becomes 5.6-142.6 m < ³ > N / min. In the conventional method, the concentration ratio is limited to about 10 times, except when the processing gas concentration is extremely low.

[0025]

As described above, in the present invention, since the regenerated heated air is circulated, the regeneration is completely performed, so that the adsorption efficiency is improved.

Furthermore, since the amount of regenerated gas can be set arbitrarily, it is possible to set the concentration ratio arbitrarily even for a processing gas having an extremely low concentration. Since the amount of regenerated gas can be set arbitrarily in this way, the amount of regenerated gas also decreases by setting the concentration to be self-combustible regardless of fluctuations in the amount of treated gas and the gas concentration, which reduces the facility scale, and In particular, when this is subjected to catalytic combustion treatment, the preheating fuel is almost unnecessary (necessary only at the start of operation), and the operating cost can be greatly reduced.

[Table 1]

[Brief description of drawings]

FIG. 1 is a schematic flow chart of Example 1 of the method of the present invention.

FIG. 2 is a schematic flow chart of Example 2 of the method of the present invention.

FIG. 3 is a schematic flow chart of Example 3 of the method of the present invention.

FIG. 4 is a schematic diagram for explaining adsorption capacity.

FIG. 5 is a schematic perspective view of a conventional concentrated deodorizing device.

FIG. 6 is a schematic flow chart of a conventional method.

[Explanation of symbols]

 1 Honeycomb rotor 2 Adsorption zone 3 Regeneration zone, 4 Cooling zone 6 Heating heater 8 Regeneration fan 9 Air volume adjustment damper 10 Air volume adjustment damper 10 'Automatic air volume adjustment damper 11 Air volume adjustment damper 12 Concentration detector 13 Fan 14 Air volume adjustment damper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B01D 53/34 ZAB

Claims (6)

[Claims] 1. A method for controlling a concentration ratio in a concentration type deodorizing device having a honeycomb rotor divided into an adsorption zone, a regeneration zone and a cooling zone, wherein regeneration heating is supplied from the cooling zone to a regeneration zone through a heater. A method for controlling the concentration ratio of the gas concentration of the heating air for regeneration by circulating a part of the air. 2. The method according to claim 1, wherein a part of the circulation of the heating air for regeneration is performed by a branch path branching from a downstream side of the regeneration zone to an upstream side of the regeneration zone. . 3. The method according to claim 1, wherein the gas concentration of the heating air for regeneration is detected downstream of the regeneration zone, and the gas concentration of the heating air for regeneration is controlled based on the detection result. Method. 4. The method according to claim 3, wherein the control of the gas concentration is controlled by a signal from a concentration detector provided between the cooling / cooling zone and the heater and detecting the gas concentration of the regenerated gas. A method characterized by being performed by an automatic air volume adjustment damper. 5. The method according to claim 4, wherein the gas concentration of the regeneration gas is set to 1/3 or less of the lower explosion limit. 6. The method according to claim 1, wherein a part of the cooling air passing through the cooling zone is branched and used as heating air for regeneration.