JPH05115744A - Exhaust treatment of painting booth - Google Patents

Abstract

PURPOSE:To adsorb and remove org. solvents having a low b.p. to a high b.p. CONSTITUTION:The exhaust gas discharged from a painting booth 7 is passed through a front org. solvent adsorbing rotor 13 and a high b.p. solvent containing an aromatic solvent is adsorbed while a low b.p. solvent is positively expelled and, next, the exhaust gas is passed through a rear org. solvent adsorbing rotor 14 rotated at a speed different from that of the rotor 13 in the direction reverse to that of the rotor 13 to adsorb the low b.p. solvent. By this constitution, all of the org. solvents from the low b.p. solvent to the high b.p. solvent contained in the exhaust gas can be removed. Desorbing heated air is passed through the rear org. solvent adsorbing rotor 14 and the front org. solvent adsorbing rotor 13 in succession and the temp. of the desorbing heated air flowing in the front solvent adsorbing rotor 13 is lowered to suppress the oxidative reaction of the aromatic solvent to prevent not only the formation of a thermally deteriorated substance but also the clogging of the front and rear org. solvent adsorbing rotors 13, 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust treatment method for a coating booth for efficiently removing low-boiling and high-boiling organic solvents contained in exhaust gas discharged from the coating booth. ..

[0002]

2. Description of the Related Art Various kinds of organic solvents are used for coating automobiles, from low boiling solvents having a boiling point of around 80 ° C to high boiling solvents having a boiling point of around 200 ° C. Therefore, the exhaust gas discharged from the coating booth contains various solvents from the low boiling point solvent to the high boiling point solvent in a mixed state. All organic solvents up to the high boiling point must be removed.

Various methods have been conventionally known for removing an organic solvent, and one of them is a so-called disc type adsorption rotor in which an adsorption element 1 formed of activated carbon fiber is wound in a rotor shape as shown in FIG. Is used. In this method, while slowly rotating the disk-shaped rotor, while the raw gas 2 containing the organic solvent passes through the adsorption element 1, the organic solvent contained in the raw gas 2 is applied to the adsorption element 1. The adsorption element 1 is adsorbed and discharged as clean air 3, and on the other hand, the desorption heating air 4 heated to a predetermined temperature is passed through a portion different from the passage portion of the raw gas 2 of the adsorption element 1 to adsorb the adsorption element 1. The organic solvent adsorbed on the adsorbent is desorbed and discharged together with the desorption heating air 4 from the adsorbing element 1, thereby recovering the adsorbing ability of the adsorbing element 1. By carrying out in parallel, the exhaust gas discharged from the coating booth is continuously treated.

Next, what is shown in FIG. 6 is a cylinder type adsorption rotor in which the adsorption element 1 is arranged vertically with respect to the disk type of FIG. 5, and the raw gas 2 is rotated while slowly rotating the adsorption element 1 as shown by the arrow. Is passed from the outer peripheral direction of the adsorbing element 1 to adsorb the organic solvent to form clean air 3 and discharge it. On the other hand, the desorption heating air 4 is introduced from the axial direction of the adsorbing element 1 to ventilate a part of the cylinder-type adsorbing element 1 in the diametrical direction so that the solvent is desorbed and discharged. In this way, by performing adsorption and desorption in parallel, the exhaust gas discharged from the coating booth is continuously processed.

The processing apparatus shown in FIG. 7 is provided with a filter 6 in front of the cylinder type adsorption rotor described in FIG. 6, and the mist contained in the gas while the raw gas 2 passes through the filter 6. And dust are removed. Then, the raw gas 2 from which the mist and dust have been removed is passed from the outer peripheral direction of the adsorbing element 1 to adsorb the organic solvent and discharge it as clean air 3. On the other hand, the desorption heating air 4 is introduced in the axial direction of the adsorption element 1 to be desorbed and discharged in the diameter direction of the adsorption element 1. In this way, by performing adsorption and desorption in parallel, the exhaust gas discharged from the coating booth is continuously processed.

[0006]

The above-mentioned conventional methods for treating exhaust gas containing an organic solvent have the following problems because they use one adsorption element for adsorption and desorption. ..

That is, the exhaust gas discharged from the coating booth contains various kinds of organic solvents ranging from low boiling point solvents to high boiling point solvents. The high boiling point solvent has a property that it is more easily adsorbed by the adsorption element than the low boiling point solvent.
Therefore, in the case of treating exhaust gas mixed with various kinds of organic solvents having different adsorptivity as described above with one adsorption element,
The phenomenon that the low boiling point solvent once adsorbed on the adsorbing element is expelled by the adsorption of the high boiling point solvent having good adsorbability,
There is a pollution problem that the exhaust gas is exhausted without removing the low boiling point solvent.

Further, in the case of exhaust treatment of an automobile coating booth, since the temperature of the heating air for desorption is about 130 ° C., the oxidation reaction of the aromatic solvent contained in the organic solvent is promoted during desorption. As a result, a thermally altered substance is generated, and this thermally altered substance accumulates in the adsorption element to reduce the adsorption ability of the adsorption element.

The present invention has been made in view of the above points, and adsorbs and removes all high-boiling point solvents from low-boiling point solvents and prevents the formation of heat-altered substances to efficiently contain organic solvents. The present invention provides an exhaust gas treatment method for a coating booth that treats exhaust gas.

[0010]

Means for Solving the Problems According to the present invention for solving the above problems, an organic solvent is adsorbed through an exhaust gas to an adsorption portion of an organic solvent adsorption rotor, and the adsorbed organic solvent is adsorbed on the organic solvent adsorption rotor. The exhaust gas is desorbed by passing through the desorption part of the desorption heat air to continuously treat the exhaust gas while maintaining the adsorption capacity of the organic solvent adsorption rotor, and various organic solvents from low boiling point solvent to high boiling point solvent are used. The exhaust gas containing the gas is passed through the organic solvent adsorption rotor of the preceding stage, and the rotation direction is opposite to that of the organic solvent adsorption rotor of the preceding stage, and
The organic solvent contained in the exhaust gas is adsorbed through the rear-stage organic solvent adsorption rotor with different rotation speed, and desorption is performed by passing heated air from the rear-stage organic solvent adsorption rotor side to the front-stage solvent adsorption rotor side. It is characterized by that.

[0011]

According to the present invention, when the exhaust gas discharged from the coating booth passes through the organic solvent adsorption rotor in the preceding stage, the present invention is configured as described above, while actively expelling the low-boiling point solvent such as an aromatic solvent. The high boiling point solvent containing is adsorbed.
Since the desorption heating air is made to pass from the rear side organic solvent adsorption rotor side to the front side organic solvent adsorption rotor side, the temperature of the desorption heating air is lowered by the rear side organic solvent adsorption rotor. The temperature is low at the time of passing through the organic adsorption rotor. As a result, the oxidation reaction of the aromatic solvent or the like adsorbed on the organic solvent adsorption rotor in the preceding stage is suppressed, and the generation of the thermally altered substance does not occur. Next, the exhaust gas containing the low boiling point solvent passes through the organic solvent adsorption rotor in the subsequent stage. Therefore, the latter organic solvent adsorption rotor has a reverse rotation direction and a different rotation speed from the former organic solvent adsorption rotor, so the former organic solvent adsorption rotor passes through a portion with a large adsorption amount and a low adsorption force. The exhaust gas containing the low boiling point solvent passes through the part where the adsorption amount of the organic solvent adsorption rotor in the latter stage is small and the adsorption power is high, and the portion where the adsorption force of the organic solvent adsorption rotor in the former stage is low and the latter stage The adsorption ability is averaged with the portion having a high adsorption force of the organic solvent adsorption rotor, and the low boiling point solvent having a low adsorption ability is surely adsorbed in the portion having a high adsorption force of the organic solvent adsorption rotor in the subsequent stage. Since the aromatic solvent is adsorbed and removed by the organic solvent adsorption rotor in the preceding stage, no heat-altered substance is generated even if the temperature of the heating air for desorption is high.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIG. 1, the exhaust gas generated in the coating booth is sent to the concentrator 9 by the exhaust fan 8. In the concentrator 9, the exhaust gas first passes through the primary filter 10 and the secondary filter 11 to remove the paint mist and dust contained in the exhaust gas, and then is slightly contained when passing through the granular activated carbon 12. By removing the plastic material that is present, the clogging of the organic solvent adsorption rotor 13 in the previous stage and the accumulation of non-desorption components are prevented.

The front organic solvent adsorption rotor 13 and the rear organic solvent adsorption rotor 14 are composed of a drive motor 17, a front organic solvent adsorption rotor 13 and a drive motor 18, and a rear organic solvent adsorption rotor 14 as shown in FIG. Belts 19 and 20 hung between
Thus, they rotate in opposite directions (arrows). Then, the duct 21 allows the inlet / outlet portion 15 of the heating air for desorption
And an outlet portion 16 are formed, and the exhaust gas passes from the organic solvent adsorption rotor 13 in the front stage to the organic solvent adsorption rotor 14 in the rear stage as shown by an arrow G, while the heating air for desorption is indicated by an arrow A.
As described above, the gas flows from the inlet portion 15 into the organic solvent adsorption rotor 14 in the subsequent stage to be desorbed, then flows into the organic solvent adsorption rotor 13 in the upstream stage via the duct 21, is desorbed, and flows out from the outlet portion 16 as indicated by arrow B.

Therefore, the primary filter 10 and the secondary filter 11
The paint mist and dust contained in the exhaust gas passing through the exhaust gas are removed, and the exhaust gas from which the plastic material, etc. slightly contained when passing through the granular activated carbon 12 is removed, is adsorbed by the organic solvent in the previous stage. When passing through the rotor 13, by positively utilizing the phenomenon that the high-boiling point solvent having a high adsorbability drives out the low-boiling point solvent having a low adsorbability, the low-boiling point solvent is actively driven out and the aromatic solvent is included. Adsorb high boiling solvents.

On the other hand, the desorption heating air is sent to the organic solvent adsorption rotor 14 in the subsequent stage, and desorbs the organic solvent adsorbed in the organic solvent adsorption rotor 14 in the subsequent stage. In this desorption, the temperature of the desorption heating air (about 130 ° C.) is lowered to a low temperature (about 105 ° C.) at the time of desorption after passing through the organic solvent adsorption rotor 13 in the previous stage. As a result, the oxidation reaction of the aromatic solvent adsorbed on the organic solvent adsorption rotor 13 in the preceding stage is suppressed, and the generation of the heat-altered substance does not occur.

Next, the exhaust gas containing the low boiling point solvent passes through the organic solvent adsorption rotor 14 in the subsequent stage. Therefore, since the organic solvent adsorption rotor 14 in the latter stage has a rotation direction opposite to that of the organic solvent adsorption rotor 13 in the former stage and has a different rotation speed, the organic solvent adsorption rotor 13 in the former stage has a high boiling point containing an aromatic solvent. The exhaust gas containing the low boiling point solvent that has passed through the part where the adsorption amount of the solvent is large and the adsorption force is reduced, the adsorption amount of the organic solvent in the organic solvent adsorption rotor 14 in the subsequent stage is small and the adsorption force is still reduced. As a result of passing through a portion which has not been subjected, a portion where the adsorption capacity of the organic solvent adsorption rotor 13 in the former stage has deteriorated and a portion in which the adsorption capacity of the organic solvent adsorption rotor 14 in the latter stage has not yet deteriorated are comprehensive. The low-boiling point solvent having a low adsorbability is uniformly adsorbed by the organic solvent adsorption rotor 14 in the subsequent stage, and is discharged as clean air 22. Since the aromatic solvent has been adsorbed and removed by the organic solvent adsorption rotor 13 in the preceding stage, even if the temperature of the heating air for desorption is high, there is no generation of a heat-altered substance in the organic solvent adsorption rotor 14 in the subsequent stage.

An example of the rotation speeds of the organic solvent adsorption rotor 13 of the first stage and the organic solvent adsorption rotor 14 of the second stage is shown. The rotation speed of the organic solvent adsorption rotor 13 of the first stage is one revolution per hour, and the organic solvent adsorption rotor of the second stage is shown. The rotation speed of 14 is 5 revolutions per hour. Further, the averaging of the adsorption ability will be described with reference to FIG. 4 showing an experimental example comparing with the conventional one using one adsorption element. Referring first to FIG. 3 in connection with the description of FIG. 4, the adsorption rotor rotates in the direction of the arrow, and (a) is the desorption section (b) is the adsorption section. Adsorption part (b) A, B,
C and D are measurement points of adsorption rate.

In FIG. 4, the abscissa plots the points A, B, C, and D corresponding to the above measurement points, and the ordinate plots the adsorption rate, and the measurement results are plotted. According to this, two rotors, the organic solvent adsorption rotor 13 in the front stage and the organic solvent adsorption rotor 14 in the rear stage are provided, the rotation directions of the two rotors are reversed, and the rotation speed of the organic solvent adsorption rotor 13 in the front stage is one revolution per hour. , When the rotation speed of the organic solvent adsorption rotor 14 of the latter stage is set to five revolutions per hour, the adsorption rate during passage from the organic solvent adsorption rotor 13 of the former stage to the organic solvent adsorption rotor 14 of the latter stage is as shown by the line X. In contrast, it is constant at the adsorption portion (b), whereas in the conventional one, it drops sharply from the measurement point C. The reason for this is that in the case of the present embodiment, the rotation directions of the two are reversed and the rotation speeds are made different, so that
13 High adsorption capacity and organic solvent adsorption rotor in the latter stage
This is because the adsorption capacity of 14 is low, or the adsorption capacity of the organic solvent adsorption rotor 13 at the front stage is low and the adsorption capacity of the organic solvent adsorption rotor 14 at the rear stage is high, and the adsorption capacities complement each other. In the above example, the exhaust from the automobile coating booth is described as an example, but depending on the type of solvent in the exhaust gas, the rotation speed of the organic solvent adsorption rotor 13 in the front stage may be made faster than the rotation speed of the organic solvent adsorption rotor 14 in the rear stage. Then, the rotation speed may be reversed. Further, in the present embodiment, the case where the organic solvent adsorption rotor has two stages, that is, the former stage and the latter stage has been described, but it is not necessary to provide two organic solvent adsorption rotors and they may be provided in multiple stages.

In this way, the desorption heating air is desorbed by the organic solvent adsorption rotor 14 in the subsequent stage, subsequently desorbed by the organic solvent adsorption rotor 13 in the preceding stage, and is discharged from the outlet section 16. Here, since the amount of heating air for desorption is smaller than the amount of exhaust gas, the organic solvent is concentrated by the desorption of the heating air for desorption. The organic solvent concentrated in this way is used in the combustion device.
After being burned in 23, the heat of the combustion heats the outside air 26 in the heat exchanger 24, and then the desorption heating air is discharged as clean air 25. Then, the desorption heating air 27 heated by the heat exchanger 24 is supplied by the blower 28 to the organic solvent adsorption rotor 14 in the subsequent stage.

[0020]

As described in detail above, according to the present invention, the exhaust gas containing both the low boiling point solvent and the high boiling point solvent discharged from the coating booth or the like is passed through the organic solvent adsorption rotor in the preceding stage to remove the low boiling point solvent. While actively expelling, it adsorbs high-boiling point solvents including aromatic solvents, etc., and then the rotation direction is opposite to that of the organic solvent adsorption rotor in the previous stage and the rotation speed is different through the organic solvent adsorption rotor in the subsequent stage. Since the boiling point solvent is adsorbed, all the organic solvents of the high boiling point solvent can be removed from the low boiling point solvent contained in the exhaust gas. Also, by passing the heated air for desorption from the organic solvent adsorption rotor side of the latter stage to the solvent adsorption rotor side of the former stage, the high boiling point solvent adsorbed on the former stage organic solvent adsorption rotor is actively expelled by the low boiling point solvent. This makes it possible to desorb high boiling point solvents including aromatic solvents, prevent the formation of heat-altered substances, eliminate clogging of the front and rear organic solvent adsorption rotors, and improve the adsorption ability of the rotor for a long period of time. The exhaust gas discharged from the coating booth can be continuously processed.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of the present invention.

FIG. 2 is a schematic diagram of an organic solvent adsorption rotor in a front stage and an organic solvent adsorption rotor in a rear stage in FIG.

FIG. 3 is an explanatory diagram of a rotor.

FIG. 4 is a diagram showing the relationship between the measurement points of the rotor in FIG. 3 and the adsorption rate.

FIG. 5 is a schematic view showing a conventional disc type adsorption element.

FIG. 6 is a schematic view showing a conventional cylinder type adsorption element.

FIG. 7 is a perspective view of an organic solvent treatment apparatus using a conventional cylinder type adsorption element.

[Explanation of sign]

 7 Coating booth 13 Organic solvent adsorption rotor in the first stage 14 Organic solvent adsorption rotor in the second stage 15 Desorption heating air inlet 16 Desorption heating air outlet

Claims (1)

[Claims] 1. An organic solvent is adsorbed by adsorbing an organic solvent through exhaust gas to an adsorbing portion of an organic solvent adsorbing rotor, and adsorbing the adsorbed organic solvent with desorption heating air passing through a desorbing portion of the organic solvent adsorbing rotor. The exhaust gas is continuously treated while maintaining the adsorption capacity of the rotor, and the exhaust gas containing various organic solvents of low boiling point solvent to high boiling point solvent is passed through the organic solvent adsorption rotor of the preceding stage, and then the preceding stage The organic solvent adsorption rotor has a rotational direction opposite to that of the organic solvent adsorption rotor, and the rotational speed is different. An exhaust treatment method for a coating booth, which is characterized by passing the solvent from the adsorption rotor side to the solvent adsorption rotor side of the previous stage and desorbing it.