JPH02203914A - Adsorbing and desorbing apparatus - Google Patents

Abstract

PURPOSE:To lower the concn. of the org. solvent in exhaust gas at an outlet by radially partitioning an activated carbon packed drum into three or more zones to set the first zone to a desorbing zone and the second and third zones to adsorbing zones and passing gas to be treated through the adsorbing zones in series. CONSTITUTION:In a gas adsorbing and desorbing apparatus wherein an activated carbon packed drum-shaped adsorbing and desorbing chamber is tumbled, a drum 1 is radially partitioned into three or more independent zones A-C. In the rotary direction of the drum 1, the first zone is set to a desorbing zone C and the second and third zones are set to desorbing zones A, B. The gas to be treated supplied to the second zone A is further supplied to the third zone B and the adsorbing and desorbing chamber is arranged so as to treat the gas to be treated while gas is passed through two or more adsorbing zones in series. As a result, the concn. of the org. solvent in the exhaust gas at the outlet of this apparatus can be lowered. Further, the amount of desorbed vapor per recovered solvent amount can be reduced to a large extent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The adsorption/desorption device of the present invention is a simple system that can collect organic solvents in high concentration and small amount of organic exhaust gas with a recovery rate of 95%.
It is suitably used for recovery with the above-mentioned high efficiency and low running cost.

The type of activated carbon to be filled into the device does not matter, such as fibrous, granular, beaded, or powdered, but fibrous is preferable because it is easy to assemble, the quality of the recovered solvent is good, and there is no wear and tear such as crushing. It is superior.

It should be noted that the high IfiU low air flow rate specifically means that the organic solvent 11a in the exhaust gas is about 5 OOO ppm or more, and the exhaust gas treatment air flow is about iom X/min or less.

(Prior Art and Problems) Regarding the conventional treatment of high-concentration organic exhaust gas with a small air volume, the following points 1 to 2 can be pointed out in the adsorption/desorption method using activated carbon fiber as an adsorbent.

■ By adding diluted air and increasing the gas velocity that passes through the activated carbon fiber layer, activated carbon fibers are prevented from becoming overly hydrated.When treating high ini exhaust gas, the concentration is high, but the amount of gas to be processed is reduced. It is common that there are few.

If the same amount of processed gas is passed through activated carbon fiber,
The gas velocity passing through the activated carbon fiber layer is too high and the activated carbon fiber becomes overly hydrated and does not work effectively.

Typically, the gas velocity passing through the activated carbon fiber layer is 20 cm
It is appropriate to operate within the range of /s to 50cm/s.

This is because the effect of replacing and drying the steam and water remaining on the activated carbon fibers with the gas to be treated after desorption can be expected.

The lower limit of the processing gas velocity is set at 20 cm/s in order to increase the drying efficiency at that time.

In other words, the rate at which the gas to be treated passes through the activated carbon fiber layer is
If it is not kept above a certain level, the activated carbon fiber will have too much moisture.

As is well known, as the moisture content of activated carbon II increases, the adsorption rate decreases, so operating the activated carbon fiber in a state as dry as possible leads to an increase in efficiency.

■ Add dilution air to dilute the exhaust gas concentration to a concentration that is easy to treat.

In the conventional adsorption/desorption method using activated carbon fibers, organic exhaust gas is supplied to the activated carbon fibers in a temporarily moist state after completion of desorption. Therefore, if the activated carbon fiber has too much moisture immediately after switching, and residual heat remains and the activated carbon fiber is at a high temperature, when the activated carbon m-thread adsorption capacity temporarily decreases, temporary leakage occurs to the outlet side. . It was necessary to dilute it to reduce the amount of leakage.

In conventional adsorption/desorption devices using activated carbon fibers, the peak of leakage at the time of switching is due to the activated carbon #AII& temporarily becoming hot and humid as described above. This is because the gas concentration temporarily increases.

■Incorporate drying and cooling processes.

The adsorption performance of activated carbon fibers can be improved by drying the activated carbon fibers and then cooling them.

This drying and cooling process is essential for an adsorption/desorption device filled with granular activated carbon, but in the case of an adsorption/desorption device filled with activated carbon fibers, it is necessary to avoid heavy equipment. , this process is often not included.

However, although this would simplify the apparatus, it would be necessary to accept that the gas concentration on the outlet side of the apparatus would instantaneously rise slightly at the time of switching as described above.

An adsorption/desorption device using activated carbon is essentially a concentrator.

From its original purpose, the dilution methods described in (1) and (2) above are unreasonable.

(Object and Structure of the Invention) The present invention aims to provide an adsorption/desorption device that solves the problems seen in the prior art.

The present invention is as follows.

In a gas adsorption/desorption device in which a drum-shaped adsorption/desorption chamber filled with activated carbon moves axially, the drum is radially partitioned into three or more independent zones, with the first zone serving as the desorption zone and the second zone in the rotational direction of the drum. , the third zone is an adsorption zone, and the gas to be treated that is supplied to the second zone is further supplied to the third zone, and the gas to be treated is passed through two or more adsorption zones=5 in series for treatment. A rotating drum type adsorption/desorption device characterized by having an adsorption/desorption chamber. The adsorption/desorption device of the present invention is shown in Fig. 1 (1 to 1 in Fig. 1).
3).

FIG. 2 is a cutaway perspective view of the adsorption/desorption device in which a rotating drum is arranged.

The first of the drums divided into multiple chambers (three chambers in Figure 1)
One of the zones is a desorption zone, where the solvent adsorbed on the activated carbon is desorbed by supplying water vapor or other heat carrier. The other two chambers filled with activated carbon in the second zone and the third zone are separated by a valve and a valve seat so that the gas to be treated flows in series.

The gas to be treated is supplied to chamber A from the inner peripheral surface of the drum, passes through the activated carbon layer while the organic solvent is adsorbed, and exits to the outer peripheral surface of the drum. Next, as the gas to be treated flows from the outer peripheral surface of chamber B toward the inner peripheral surface, the organic solvent is adsorbed onto the activated carbon.

At this time, chamber A is being supplied with 11% high gas. The activated carbon in chamber A cannot adsorb the highly concentrated gas, and within a short period of time, the S degree of outgoing gas at room temperature A begins to break through.

Therefore, the medium concentration gas leaving chamber Δ is sent to chamber B.

Since it is adsorbed again in chamber B, it becomes possible to keep the concentration at the outlet [1 of chamber B, that is, the outlet of the device] extremely low.

In actual design, the amount of activated carbon, switching time, etc. are set to achieve optimal operation depending on the type of solvent, etc.

(Example) In FIG. 1, arrow I indicates the flow direction of the gas to be processed, arrow opening indicates the flow direction of the desorption gas, and arrow C indicates the rotation direction of the cylinder.

Chamber A and chamber B are arranged in series, and the gas to be treated that is supplied to chamber A passes through the adsorbent layer of chamber A and then enters chamber B.
was supplied to the adsorbent layer.

As a result, the gas to be processed was processed at room temperature A in a high concentration state, and was supplied to chamber B in a reduced concentration state.

Room B has more room for absorption than room A, so the low-concentration absorption components contained in the gas to be treated are adsorbed by the activated carbon in room B and are not discharged outside the system. Ta.

In room B, even though the activated carbon was highly moistened by desorption steam, in room A M3, drying was simultaneously performed by the gas to be treated containing adsorbed components at a low concentration.

When the activated carbon in chamber A reaches its adsorption limit, the cylinder rotates 1/3 in the direction of arrow C, and chamber A is desorbed at the position of chamber C.
Room B is located at the location of room A and is used for adsorption treatment of high-a degree gas.
After the desorption was completed, chamber C was placed in chamber B and subjected to adsorption treatment for melon gas.

The above steps were repeated to continuously process the gas to be processed.

As a result, adsorbed components were completely removed in series from the gas to be treated.

Even if adsorbed components in the adsorbed gas leaked in chamber A, the adsorption process was further carried out in chamber B, so activated carbon could be used effectively up to its saturated adsorption amount.

(Effects of the Invention) Since operation is required to keep the concentration at the device outlet low, the adsorption rate of activated carbon (the ratio of the amount of solvent adsorbed to activated carbon) must be kept low. The adsorption rate at this time is called the effective adsorption rate, and the outlet concentration in the shell is 5% of the inlet temperature.
This refers to the point at which the data begins to leak.

However, if it is considered that the concentration at the outlet of the device can be ignored, then the solvent can be adsorbed up to the adsorption limit of activated carbon. This adsorption rate is called the equilibrium adsorption rate or the saturated adsorption rate. Among activated carbons, for example, when trichlorethylene is adsorbed on activated carbon #, the effective adsorption rate is approximately 30%.
, the equilibrium adsorption rate is about 60%. In other words, even with the same amount of activated carbon, approximately twice the adsorption capacity can be utilized depending on the situation at the outlet si. The present invention has put this into practical use.

Furthermore, by arranging activated carbon in two stages in series as in the present invention, it becomes possible to adsorb the solvent to the activated carbon in the first stage up to nearly equilibrium adsorption. This means that the solvent that leaked in the first stage is adsorbed again in the second stage.

The effects of the present invention are as follows.

(2) Since high-concentration exhaust gas is treated in multiple stages, the concentration of organic solvents in the exhaust gas at the outlet of the device can be extremely low.

a. As mentioned before, the negative stage adsorbs until saturated adsorption, and the second stage switches at the point of effective adsorption, making it possible to keep the outlet exhaust gas concentration low.

b. After the desorption is completed, the chamber is switched over. Immediately after the desorption is completed, the chamber where the adsorption performance of the activated carbon layer has temporarily decreased is rotated to the adsorption process, but its position is different from the serial adsorption. I'm going to turn to the backup side.

However, at that point, the gas coming out from the first stage is supplied at a low concentration because the first stage is working effectively. Therefore, even if the adsorption performance on the backup side is reduced, the amount of solvent 11i1 that leaks to the outlet side is reduced.

Since the adsorption performance on the backup side is restored in a few seconds, even if the concentration at the backup side inlet increases thereafter, the absorption can be stopped.

■ Significant reductions in the amount of desorbed steam or other heat carrier per amount of recovered solvent can be achieved.

In the case of an adsorption/desorption device using activated carbon, the amount of vapor to be desorbed is generally proportional to the amount of activated carbon filled rather than the amount of solvent adsorbed to the activated carbon.

In other words, whether the activated carbon that has arrived at the desorption zone has adsorbed the solvent to near saturation or not so much, the amount of desorption vapor hardly changes.

For this reason, in adsorption/desorption devices using activated carbon,
What is important in terms of performance is how large amounts of solvent can be adsorbed onto activated carbon.

If activated carbon that has adsorbed solvent to near saturation is desorbed as in the method described above, it becomes possible to recover a large amount of organic solvent with a certain amount of steam, and the ratio of the recovered solvent to the amount of water vapor used, i.e. This means that the steam ratio becomes significantly smaller.

For example, if 1 kg of organic solvent can be recovered with 3 kg of steam, the steam ratio at that time will be 3.

In addition, since the amount of desorption vapor and the amount of activated carbon are almost proportional, if 1k (l) of activated carbon requires 1.2k17 of desorption vapor, if 60% of the organic solvent is adsorbed on that IkO of activated carbon, the amount of desorption vapor will be 0. This means that .6 kg of organic solvent was desorbed with 1.2 k17 of steam, and the steam ratio at that time is doubled.If only 30% of that lkO was adsorbed on the activated carbon, 0.3 k(] Since the organic solvent is desorbed with 1.2 kg of steam, the steam ratio is 4.

In the conventional type, the saturated adsorption part and the adsorption zone are combined and desorption is performed simultaneously. In comparison, in the present invention, the amount of activated carbon fiber that is detached is 1/2 that of the conventional type. This is only the room A part.

Most of that portion is activated carbon 4111f that is saturated and adsorbed. As mentioned above, since the amount of steam required for desorption is roughly proportional to the amount of activated carbon, desorption is achieved with approximately 1/2 the amount of steam compared to the conventional type.

On the other hand, when Freon R-113 is adsorbed by the apparatus of the present invention, 80% of the conventional acid recovery can be obtained with approximately 1/2 the amount of steam compared to the conventional method.

From these results, the amount of desorption steam used per recovered solvent is approximately 0.6 times (1/2 x 100/80%) compared to the conventional method.
) can be reduced to

■ Since there is no need to introduce dilution air or add drying equipment, it is possible to create a simple and compact adsorption/desorption device.

[Brief explanation of the drawing]

FIG. 1 shows an adsorption/desorption device of the present invention, 1 in FIG. 1 is a schematic diagram of the device, 2 in FIG. 1 is a front view, and 3 in FIG. 1 is a side view. FIG. 2 is a cutaway perspective view of an adsorption/desorption device equipped with a rotating drum. Patent applicant Toho Kako! ! Establishment) *6 Company Attorney Patent Attorney 1
Shi Doi 3rd part

Claims (1)

[Claims] (1) In a gas adsorption/desorption device in which a drum-shaped adsorption/desorption chamber filled with activated carbon moves axially, the drum is radially partitioned into three or more independent zones, the first zone being the desorption zone in the rotational direction of the drum, The second and third zones are used as adsorption zones, and the gas to be treated that is supplied to the second zone is further supplied to the third zone, and the gas to be treated is passed through the two or more adsorption zones in series. A rotating drum type adsorption/desorption device characterized by having an adsorption/desorption chamber.