JPH0141372B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention purifies the first gas and purifies the adsorbent by repeatedly passing a first gas containing an adsorbed substance and a second gas for desorption heating through an adsorbent housed in a case. The present invention relates to a gas purification method that performs regeneration. This type of gas purification method has the following drawbacks. (i) If the gas to be treated is mainly composed of organic solvents such as painting exhaust or printing exhaust, most of the contained substances can be easily attached and detached by the second gas, which requires relatively little heating energy to the adsorbent. It is something that can be taught. If only such substances are contained, even after repeated adsorption and desorption operations are performed for a long period of time, only a small amount will remain and accumulate on the adsorbent, and the adsorption performance of the adsorbent will deteriorate only slightly. It is. (ii) However, the first gas mentioned above contains a high boiling point substance, albeit in a small amount, and this is not desorbed by the small heating energy as mentioned above, but gradually accumulates in the adsorbent. Therefore, the adsorption performance of the adsorbent deteriorates relatively early. (iii) In order to prevent such deterioration of the adsorbent,
It is sufficient to increase the heating energy of the second gas when shown in (i) above, but as shown in the table below, the thermal energy of the second gas heats the solvent etc. adsorbed by the adsorbent. The amount used is about 2 to 10% of the total.

[Table] (iv) In other words, if heating energy is increased to remove high boiling point substances, the heat loss will increase significantly, and most low boiling point substances will be heated excessively. However, this amount becomes a heat loss, and a large heat loss cannot but be caused as a whole. On the contrary, if the amount of heat supplied in one regeneration from the second gas is reduced, the loss of heat can be reduced, but sufficient regeneration processing cannot be performed, and a separate regeneration processing device is required from the start of use. This has the disadvantage that the period during which treatment is required (hereinafter referred to as life span) becomes shorter and the operating rate deteriorates. For this reason, in the past, an appropriate fixed amount of heat to be supplied was set based on the relationship between the heat loss and the operating rate, and this set amount of heat was supplied by the second gas for each regeneration. However, it is extremely difficult in practice to appropriately determine such a constant amount of heat to be supplied due to various factors such as fluctuations in the humidity of the first gas and the concentration of adsorbed substances contained therein. SUMMARY OF THE INVENTION The present invention addresses these drawbacks and aims to reduce the amount of heat required over the lifespan compared to the conventional setting of a constant supply amount of heat. In order to achieve this object, the present invention employs a configuration in which the amount of heat given to the adsorbent by the second gas is intermittently increased at predetermined intervals in the gas purification method described above. By intermittently increasing the amount of heat supplied by the second gas in this way, good desorption is achieved during this period, and even if the amount of heat supplied other than this period is lower than usual, good regeneration is achieved overall. be able to maintain the condition. Therefore, the lifespan can be significantly increased compared to the amount of heat supplied. Next, examples of the present invention will be described. First Embodiment (See FIG. 2) FIG. 2 is a system diagram of piping, etc. of a continuous adsorption/desorption device, which is an example of the device used to carry out the present invention. A hunk-shaped adsorbent body 2 is placed around the rotation center axis 1.
(As the adsorbent, activated carbon fiber or
A paper body made of powdered activated carbon and mixed with a fibrous substance is attached to the case 3 that covers the adsorbent 2.
A gas (first gas) 4 containing organic solvents, which is exhaust gas from a painting booth or other factory, is blown into a first region 5 and a blower 6, and is heated by a heating device 7, which will be described below. and a second region 9 through which heated gas (second gas) 8 passes. Then, the adsorbent 2 is rotated around the central axis 1 at a constant speed in a constant direction, so that the two regions 5 and 9 are sequentially passed through, and the first gas 4 and the second gas 8 are passed alternately. It is structured as follows. The heating device 7 is provided with a heating temperature adjustment structure (details will be described below), and the temperature of the second gas 8 can be changed according to the following pattern. () The low temperature To corresponding to the above heat amount T is 100℃~
The temperature shall be constant within 150℃. () The high temperature Tho corresponding to the heat amount Th is set to be a constant temperature within 125°C to 160°C, which is higher than the low temperature To in the above (). () When the residual rate S increases due to regeneration at low temperature To (this occurs after approximately 3 to 100 regenerations depending on the setting of low temperature To), the next regeneration temperature is set to the high temperature Th. do. This one time is the time required for one rotation of the adsorbent 2. In order to change the temperature of the second gas 8 in such a pattern, the following configuration is adopted. When the temperature and air volume of the first gas 4 and the concentration of adsorbed substances are generally stable, the above patterns () to () are controlled by a timer. The heating device 7 is as follows. In the electric heating type, the heating temperature is adjusted by adjusting the number of electric heating elements and the amount of electricity. In a gas or oil burner type, the heating temperature is adjusted by adjusting the number of burners and the amount of gas or oil supplied to each burner. A heating device 7 uses a catalytic method to heat the second gas 8 after desorption.
In the case of heating the second gas 8 by catalytically combusting the organic solvent that has been returned and desorbed, the amount of air supplied before catalytic combustion and the amount of air supplied after combustion are adjusted to reduce the Adjusting the temperature of the second gas 8 Note that in any of these means, the amount of air passing through the adsorbent 2 is substantially constant. In the method described above, the temperature of the second gas 8 is adjusted to change the amount of heat supplied to the adsorbent 2,
The temperature of the adsorbent 2 during desorption usually does not rise to a high temperature, so organic solvents with low desorption temperatures decompose or polymerize at high temperatures and strongly adhere to the adsorbent 2, causing regeneration of the adsorbent 2. It does not accelerate deterioration that would make it impossible, and has the effect of significantly extending the life of the adsorbent 2. In addition, the time to maintain the high temperature Tho continuously is 1
The rotation time of the adsorbent 2 is not limited to 2 times or 3 times. Further, the direction in which the gases 4 and 8 pass through the adsorbent 2 is not limited to the axial direction, but may be in the radial direction. In the figure, 10 is a post-processing device for the second gas 8, and in the above example, this post-processing device is connected to the heating device 7.
It will be used for both. Second Embodiment (not shown) Instead of changing the temperature as described above, the temperature of the second gas 8 is kept approximately constant, and the wind speed is changed to (), (),
() Change the temperature in place of the putter. As a specific means for this, the blower 6 is configured to be variable, the wind speed is adjusted by the above (i) or (ii), and along with this wind speed adjustment, the heating amount is adjusted by the above, and the second The temperature of the gas 8 is kept approximately constant. In addition, the temperature of the second gas 8 in this case is
Stabilize anywhere between 100°C and 160°C. Third Embodiment (not shown) Instead of changing the amount of heat supplied to the adsorbent 2 by the second gas 8 due to fluctuations in temperature and wind speed as in the first and second embodiments, the amount of heat supplied to the adsorbent 2 is changed. By varying the rotational speed, the amount of heat supplied is varied as in the first embodiment. Specifically, a speed change device is incorporated into the rotary drive device of the adsorbent 2, and the temperature changes according to the pattern (), (), () above, and the rotation is performed at a predetermined high speed when the temperature corresponds to a low temperature, and at a low speed when the temperature corresponds to a high temperature. shall be. In this case, the adjustment work is easy because the blower 6 and the heating device 7, which are generally difficult to control, are not subject to fluctuation adjustment. Fourth Embodiment (not shown) A batch-type method in which purification is performed by alternately supplying the first gas 4 and the second gas 8 in a predetermined order to an adsorption block chamber containing a plurality of adsorption towers containing adsorbents. The first and second embodiments can also be implemented in an adsorption device. In such a case, one desorption time means one desorption time in each column or chamber, and does not necessarily need to be interpreted as limited to the time for one cycle through a plurality of columns or chambers. However, since a plurality of towers or chambers generally have the same adsorption capacity, in such a case, the time for one circulation may be considered as one adsorption time. In addition, when applying the measures in the third embodiment to this tower or chamber, it is sufficient to intermittently increase one passage time in each tower or chamber. In the detailed embodiment described above, the second gas 8 is not limited to air, but also steam or nonflammable gas (in the heating means of the first embodiment, it contains a large amount of noncombustible gas after combustion and is substantially nonflammable). In addition, the temperature of the second gas 8, the wind speed, the temperature and the passing time (in the first embodiment, the rotation time of the adsorbent 2), or the wind speed and the passing time. It is also good to change them simultaneously.

[Brief explanation of drawings]

The drawing shows an embodiment of the gas purification method according to the present invention, and is a flowchart showing a first embodiment. 2... Adsorbent, 3... Case, 4... First gas, 8... Second gas.

Claims (1)

[Scope of Claims] 1. Repeatedly passing a first gas 4 containing an adsorbed substance and a second gas 8 for desorption heating through an adsorbent 2 housed in a case 3, and 2. A gas purification method in which the amount of heat given to the adsorbent 2 by the gas 8 is intermittently increased at predetermined intervals. 2 Case 3 is one in which the location of the adsorbent 2 is substantially divided into a passage area 5 for the first gas 4 and a passage area 9 for the second gas 8, and the adsorbent 2 is moved in a predetermined direction. By being continuously rotated, the first gas 4
The method for purifying a gas according to claim 1, wherein the gas and the second gas 8 are passed alternately. 3. The gas purification method according to claim 1 or 2, wherein the temperature of the second gas 8 is intermittently increased to intermittently increase the amount of heat transferred to the adsorbent 2. 4. Gas purification according to claim 1 or 2, in which the time for one passage of the second gas 8 is intermittently increased to intermittently increase the amount of heat transferred to the adsorbent 2. Method. 5. The gas purification method according to claim 1 or 2, wherein the wind speed of the second gas 8 is intermittently increased to intermittently increase the amount of heat transferred to the adsorbent 2. 6. A gas purification method according to claim 2, in which the rotational speed of the adsorbent 2 is intermittently reduced to intermittently increase the amount of heat given to the adsorbent 2. .