JPH03193111A - Adsorbing body - Google Patents

Abstract

PURPOSE:To enhance the surface coverage of the substance to be adsorbed on an adsorbing body by providing fibrous activated carbon to the treated gas outlet part of the main body of the adsorbing body formed by alternately laminating granular activated carbon layers and planar heaters. CONSTITUTION:Fibrous activated carbon 13 is provided to the treated gas outlet part of the main body 20 of an adsorbing body formed by alternately laminating granular activated carbon layers 12 and planar heaters 11. As a result, the adsorbing quantity per a unit volume of the substance to be adsorbed on the adsorbing body can be increased and, at the time of the regeneration of the adsorbing body by heating, a regeneration time can be shortened and the lowering of a recovery rate can be prevented and, further, a regeneration apparatus can be miniaturized by simple equipment and, furthermore, the economically excellent adsorbing body is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an adsorbent used for recovering fluorocarbon gas in semiconductor cleaning equipment, for example.

[Conventional technology]

In an adsorbent that adsorbs and removes adsorbed substances contained in a gas to be treated using activated carbon, adsorption characteristics vary depending on the shape and characteristics of the activated carbon used.

In other words, granular activated carbon (spherical, cylindrical, crushed, etc.) is generally several millimeters in size and has both macropores and micropores, so the adsorbed substance gradually diffuses from the macropores into the micropores. The rate of adsorption of the adsorbed substance onto the adsorbent is relatively slow, and therefore it takes a long time to desorb the adsorbed substance adsorbed onto the adsorbent by heating or the like. Furthermore, in order to reduce the content of adsorbed substances contained in the processed gas that has passed through the adsorbent,
Increasing the flow rate of the desorption medium or increasing the desorption temperature, etc.
Stricter attachment/detachment conditions are required.

On the other hand, fibrous activated carbon generally has a diameter of several μm to
Since it is made up of fibers of several tens of micrometers and has micropores only on the outer surface, it has the advantage that the adsorption rate is much faster than that of granular activated carbon. ), the amount of adsorption per unit volume is small.

Therefore, in order to efficiently adsorb or desorb the adsorbed substance, it is necessary to perform the desorption in a short time.

[Problem to be solved by the invention]

By the way, as mentioned above, although granular activated carbon has a large adsorption amount per unit volume, it takes a long time for desorption, so the amount of activated carbon used increases, resulting in an increase in weight.
Another problem is that the recovery rate of the adsorbed substance adsorbed by the adsorbent decreases if it is not desorbed for a long time.

On the other hand, with fibrous activated carbon, the amount of adsorption per unit volume is small and the desorption time is short, so the amount of activated carbon used can be reduced compared to granular activated carbon, but the activated carbon cost per weight is lower than that of granular activated carbon. Tens to hundreds of times higher. Furthermore, it is difficult to increase the packing density, and furthermore, the pressure loss is large.

Considering the advantages and disadvantages of granular activated carbon and fibrous activated carbon as described above, fibrous activated carbon is generally considered to be more advantageous, but fibrous activated carbon shortens the regeneration time of the adsorbent, that is, the desorption time. There is a restriction that it must be carried out within a certain amount of time, and steam regeneration is generally used as a method for regenerating adsorbents. Therefore, when using two to several adsorption towers by switching, the adsorption time is determined by the desorption time, so if the desorption time takes a long time, the amount of activated carbon used will increase, and granular activated carbon is more advantageous. turn into.

In addition, when using steam as a method of regenerating the adsorbent, it is necessary to use a steam source that generates the steam, and when the steam condenses into water, some of the desorbed substances are dissolved in the water, so the condensed water It is necessary to separate the adsorbed substances into water and the adsorption tower, and a drying process is also required to dry the inside of the adsorption tower, which requires complicated equipment and increases the size of the regeneration equipment. have.

The present invention has been made in view of the above-mentioned conventional problems, and it is possible to increase the adsorption amount of a substance to be adsorbed onto an adsorbent per unit volume, and also to heat the adsorbent. During regeneration, it is possible to improve thermal efficiency and shorten the regeneration time, prevent a decrease in recovery rate, and furthermore, it is possible to downsize the regeneration equipment with simple equipment.
Furthermore, it is an object of the present invention to provide an economically superior adsorbent.

[Means to solve the problem]

The present invention provides an adsorbent characterized in that fibrous activated carbon is attached to the treated gas outlet of an adsorbent main body in which granular activated carbon layers and planar heating elements are alternately laminated.

[Effect]

According to the adsorbent according to the present invention, the adsorbed substance contained in the gas to be treated is adsorbed and removed not only by the granular activated carbon but also by the fibrous activated carbon, which has a much faster adsorption rate than the granular activated carbon. Granular activated carbon The layers are heated evenly.

Since the adsorption capacity of granular activated carbon decreases as the temperature increases, the substances adsorbed on the granular activated carbon are desorbed by the heating. In addition, if you try to increase the recovery rate of adsorbed substances using only granular activated carbon, the regeneration (desorption) time will take a long time and a large amount of activated carbon will be required. By attaching fibrous activated carbon, which has a much faster adsorption/desorption rate than granular activated carbon, to the treated gas outlet of the adsorbent body, the recovery rate of the adsorbed material can be improved even when the regeneration (desorption) time is shortened. It is possible to prevent the decline.

Furthermore, the regeneration (desorption) time of the adsorbent is determined by the regeneration (desorption) time of the granular activated carbon, so within this time, the adsorbed substances adsorbed on the fibrous activated carbon are almost completely removed from the fibrous activated carbon. desorption, thereby regenerating the adsorbent.

〔Example〕

Examples of the present invention will be described below based on the drawings, but the present invention is not limited thereto.

1 to 3 show examples of the adsorbent of the present invention, and the adsorbent 10 is made by alternately laminating annularly formed planar heating elements 11 and granular activated carbon 12. A cylindrical adsorbent main body 20 is formed, and a processing gas outlet portion of the adsorbent main body 20 (in this embodiment, the adsorbent main body 20 serves as a processing gas outlet).
Fibrous activated carbon 13 is attached to the outer circumferential surface of the fiber.

Although the shape of the sheet heating element 11 is annular, it is not limited to this shape.

In the present invention, instead of the planar heating element 11, a spiral, ribbon-shaped, net-shaped, or cylindrical heating element may be used.

Furthermore, the adsorbent 10 shown in the above embodiment has a planar heating element 1
1 and granular activated carbon 12 are alternately stacked layer by layer to form a cylindrical shape, but it is not necessarily limited to this, and the structure and shape are arbitrary.

Furthermore, in this embodiment, the fibrous activated carbon 13 is attached to the outer circumference of the adsorbent main body 20, but it is not necessarily limited to this. It is also possible to attach it to both sides.

Next, in order to explain the adsorbent of the present invention in more detail, in the recovery process of fluorocarbon gas in semiconductor cleaning equipment,
Let us take as an example the case where the adsorbent 10 shown in the previous embodiment is used.

FIG. 4 shows a fluorocarbon gas recovery device, and the fluorocarbon gas recovery device 30 includes a suction blower 40, an adsorption tower 50,
．． 50', an air filter 60, a vacuum pump 70, a cooler 80 and a recovery device 90. In this example, two adsorption towers 50 and 50' are used and are switched alternately.

The suction blower 40 is a blower for suctioning the processed gas A containing fluorocarbon gas from a semiconductor cleaning device (not shown).

The adsorption tower 50.50' is a gas to be treated A containing fluorocarbon gas.
The adsorbent body 10 is made up of an adsorbent body 20 formed by alternately stacking sheet heating elements 11 and granular activated carbon 12, and fibrous activated carbon 13 attached to the outer periphery of the adsorbent body 20. The adsorbent 10 is filled with the gas to be treated A.
A sealing member 51 is provided on the bottom surface to prevent the gas from flowing into the processing gas B.
．． 51' is provided, and partition plates 52 and 52' are provided on the upper surface.

Further, the planar heating elements 11 constituting the adsorbent 10 are connected to energizing devices 54 and 54' via lead wires 53 and 53', respectively.
It is connected to the.

Here, gas inlets 55, 55' are provided at the upper ends of the adsorption towers 50, 50', and process gas outlets 56, 56' are provided at the lower ends. Further, the gas suction ports 55 and 55' are connected to the gas suction pipe 41 through valves 42 and 42', and the gas suction pipe 41 is connected to the suction blower 40.

Furthermore, the process gas outlet 56.56' is connected to the valve 62.62.
', and the processing gas exhaust vibro 1 is connected to the air filter 60.

In addition, the treated gas outlet 56.56 of the adsorption tower 50.50'
', respectively, are carrier valves 57 and 57'.
is installed, and a thermometer 58 is installed outside the adsorption tower 50.50'.
．． 58' is provided.

In addition, the to-be-treated gas inlet 55.5 of the adsorption tower 50.50'
A fluorocarbon gas recovery lower 1.71' is provided at a position close to the valve 72.7.
It is connected to a pressure reducing pipe 73 via 2'. The pressure reducing pipe 73 is connected to the vacuum pump 70 via a pressure gauge 74.

The cooler 80 uses cooling water as a cooling medium to condense the air-containing fluorocarbon gas conveyed from the vacuum pump 80 , and is connected to the vacuum pump 70 via a pipe 81 .

The recovery device 90 is a device for separating fluorocarbons and water that have been cooled and liquefied by the cooler 80, and for returning uncondensed fluorocarbon gas to the adsorption tower 50 (or 50') again. 92, an air chamber 93, a fluorocarbon recovery tank 94, and a water recovery tank 95.

Here, the oil/water separator 92 is connected to the cooler 80 via a pipe 91. Further, the oil/water separator 92 is provided with a level gauge 92a, the fluorocarbon recovery tank 94 is provided with a level gauge 94b and a valve 94c, and the water recovery tank 95 is provided with a level gauge 95a and a valve 95.
b is provided.

Furthermore, an air chamber 93, a fluorocarbon recovery tank 94
and water recovery tank 95 are connected to oil/water separator 92 via pipe 94a and pipe 95a, respectively.

Further, the air chamber 93 is an air cushion tank, and is connected to the suction blower 40 via a vibrator 100, and a valve 101 is provided in the middle.

Next, the effect will be explained.

First, the processed gas A containing fluorocarbon gas generated in the semiconductor cleaning process is sucked by the suction blower 40, passes through the processed gas suction pipe 41, and is sucked into the adsorption tower 50 from the processed gas inlet 55. At this time, the adsorption tower 5
0 to be processed gas inlet 55 and to be processed gas inlet pipe 41
The valve 42 provided between the adsorption towers 50' and 42 is opened.
2' is closed.

In this example, two adsorption towers 50.50' are provided, but the number of adsorption towers is not limited to this.

The to-be-treated gas A sucked into the adsorption tower 50 from the to-be-treated gas inlet 55 passes through the adsorbent 20, and the fluorocarbon gas contained in the to-be-treated gas A is adsorbed and removed, and is discharged to the treated gas section B. .

At this time, the fluorocarbon gas contained in the gas to be treated passes through the granular activated carbon layer 12 and then through the fibrous activated carbon 13, which has a much faster adsorption rate than the granular activated carbon.
The rate of adsorption of fluorocarbon gas onto the adsorbent 10 is improved compared to when only the granular activated carbon 12 is used.

The discharged processing gas passes through the processing gas discharge vibro 1 and is conveyed to the air filter 60, where fine powder such as activated carbon is filtered out.
Emitted into the atmosphere.

Note that, similar to the valve 42, a valve 6 provided between the treated gas discharge port 56 of the adsorption tower 50 and the treated gas discharge vibro 1
2 is open, and valve 62' of adsorption column 50' is closed.

Through the above adsorption process, the fluorocarbon gas contained in the gas to be treated A is adsorbed and removed by the adsorbent IO of the adsorption tower 50, and is discharged into the atmosphere as a treated gas.
When the adsorption process continues for a certain period of time, the adsorption capacity of the adsorbent 10 of the adsorption tower 50 deteriorates, and the adsorption efficiency of the fluorocarbon gas contained in the gas A to be treated deteriorates. Therefore, it is necessary to regenerate the adsorbent 10. In this case, if an attempt is made to increase the recovery rate of adsorbed substances using only the granular activated carbon 12, the regeneration (desorption) time will take a long time and a large amount of activated carbon will be required. In the case where the regeneration (desorption) time is shortened by attaching fibrous activated carbon 13, which has a much faster adsorption speed than granular activated carbon 12, to the outer periphery of the adsorbent main body 20, which is made by alternately laminating granular activated carbon 12, Even when the amount of adsorbed material is reduced, a decrease in the recovery rate of the adsorbed substance can be prevented.

The amount of fibrous activated carbon 13 is suitably 1/100 to 1/10 of the amount of granular activated carbon 12, preferably approximately 1/10.
/50.

Next, the valve 42 of the adsorption tower 50 is closed to prevent the gas to be treated A from flowing into the adsorption tower 50, and the valve 62 is closed so that the fluorocarbon gas desorbed from the adsorption body 10 is not discharged outside the adsorption tower 50. Ru.

3 Next, open valve 42' and valve 62' of adsorption tower 50'. As a result, the gas to be treated A containing the fluorocarbon gas sucked by the suction blower 40 passes through the gas to be treated suction pipe 41 and passes through the gas to be treated inlet 55' provided at the upper end of the adsorption tower 50' to the adsorption tower 50. ', and the adsorption tower 5
A process similar to the adsorption process of No. 0 is carried out. Therefore, the adsorption tower 50
Since there is no need to stop the adsorption process while the adsorbent 10 is being regenerated, the operating efficiency of the entire apparatus can be improved.

Next, after closing the valves 42 and 62 of the adsorption tower 50,
The valve 72 is opened to reduce the pressure inside the adsorption tower 50 using the vacuum pump 70, and at the same time, the energizing device 54 energizes the planar heating element 11 constituting the adsorbent 10.
1 to generate heat and uniformly heat the adsorbent 10.

The adsorption capacity of the adsorbent 10 decreases as the temperature increases, and desorption is accelerated in a reduced pressure state, so the fluorocarbon gas adsorbed by the adsorbent 10 due to the heating is desorbed from the adsorbent 10.

4 In addition, the regeneration (desorption) time of the adsorbent 10 is
Since the regeneration (desorption) time is determined by the regeneration (desorption) time of 2, the adsorbed substance adsorbed on the fibrous activated carbon 13 is almost completely desorbed from the fibrous activated carbon 13 within this time.

Note that when a normal heating element is used as in this embodiment, it is preferable to add a control device to control the heating temperature and heating rate of the adsorbent 10.

Since the pressure inside the adsorption tower 50 is reduced as shown above,
The fluorocarbon gas desorbed from the adsorbent lO is transported together with air from the fluorocarbon recovery lower 1 provided close to the gas inlet 55 to be treated, through the decompression pipe 73, to the vacuum pump 70 and the cooler 80.

The air-containing fluorocarbon gas conveyed to the cooler 80 is condensed by the cooler 80, becomes liquefied fluorocarbon and water, and is recovered in the oil-water separator 92.

The liquefied fluorocarbon and water collected in the oil-water separator 92 are separated, with liquefied fluorocarbon in the lower layer and water in the upper layer due to the difference in specific gravity.
Freon is collected in the water recovery tank 94 through a pipe 94a connected to the lower part of the oil-water separator 92, and is collected in the water recovery tank 9 through a pipe 95a connected to the upper part of the oil-water separator 92.
It will be collected on 5th.

Furthermore, since air containing fluorocarbon gas that has not been condensed by the cooler 80 remains above the oil-water separator 92, this air is sent to the air chamber 93 through a pipe 93a connected to the upper surface of the oil-water separator 92. It will be done.

The air containing fluorocarbon gas sent to the air chamber 93 is conveyed to the suction blower 40 through the pipe 100 and undergoes the adsorption process again.

After the recovery process as described above, the adsorbent IO is finally regenerated.

In this way, the adsorbent according to this example can increase the adsorption amount of the adsorbed substance to the adsorbent per unit volume, and when regenerating by heating the adsorbent, improves thermal efficiency and shortens the regeneration time. It is possible to shorten the length of the adsorbent, prevent the resulting decrease in recovery rate, and make it possible to downsize the regenerator with simple equipment.It is also economically effective6. .

Although this embodiment describes the recovery of fluorocarbon gas generated from semiconductor cleaning equipment, the present invention is not limited thereto, and can be widely used for adsorption removal and recovery of organic solvents in organic solvent-containing gases. In addition, it can be used for cleaning machine parts, processing exhaust gas containing cleaning solvents such as trichloroethane trichlorethylene from dry cleaning, processing hydrogen sulfide gas and odor-containing gas generated from human waste and industrial wastewater treatment, and even petroleum. It is also used for processing various hydrocarbon-containing gases such as refining and chemical industry products.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to increase the adsorption amount of the adsorbed substance to the adsorbent per unit volume, and when regenerating by heating the adsorbent, the regeneration can be performed with improved thermal efficiency. The time can be shortened, the recovery rate can be prevented from decreasing, and the regenerator can be downsized with simple equipment, and the adsorption system is also economically superior.

[Brief explanation of drawings]

FIG. 1 is an overall perspective view of an adsorbent according to an embodiment of the present invention, FIG. 2 is a detailed cross-sectional view of the adsorbent, FIG. 3 is a perspective view of a planar heating element constituting the adsorbent, and FIG. The figure is a schematic diagram of a fluorocarbon gas recovery device used in an embodiment of the adsorbent according to the present invention. 10; adsorbent 20; adsorbent body 30; fluorocarbon gas recovery device 40; suction blower 50; adsorption tower 50'; adsorption tower 60; air filter 70; vacuum pump 80; cooler 90; recovery device

Claims (1)

[Claims] (1) An adsorbent characterized in that fibrous activated carbon is attached to the treated gas outlet of an adsorbent main body in which granular activated carbon layers and planar heating elements are alternately laminated.