JPH08323128A - Method for self-reproducing adsorption tower - Google Patents

Abstract

PURPOSE: To provide a self-reproducing method in which the withdrawal and the transportation from an absorption tower is not required to minimize burning loss and the reproducing action is simple. CONSTITUTION: A method in which contaminated gas 1 is adsorbed and purified and the adsorption tower 3 whose purifying function has been lowered is reproduced consists of the following processes (a)-(c). That is, (a) a process in which gas 10 heated by a heat exchanger 9 is led to the adsorption tower 3 and is desorbed, (b) a process in which desorbed gas 11 from the process (a) is led to a burner 2 and is burned, and (c) a process in which combustion gas 18 from the process (b) is used as a heat source for the heat exchanger 9 before dissipating it in the air 20 are performed in order. Gas for heating in the heat exchanger of the process (a) is air, nitrogen or air rid of oxygen. The combustion gas used as the heat source of the heat exchanger of the process (c) is preferably dissipated in the air after passing it through a detoxicating treatment device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-regenerating method for an adsorption tower, which detoxifies a gas containing a harmful substance or an odorous substance by adsorption.

[0002]

2. Description of the Related Art A conventional regeneration process of an adsorption tower will be described using activated carbon as an adsorbent. First, the adsorbent having a reduced purification function is extracted from the adsorption tower, brought to a regeneration factory by transportation means such as a truck, and then, in the regeneration factory, heat regeneration treatment is performed at 600 to 900 ° C. in a reducing atmosphere. At this time, although it depends on the method of heat regeneration treatment, burning loss occurs in the most common internal heat type rotary kiln, and about 10% of fresh coal must be replenished. Heat is regenerated and new coal is replenished to make the same amount as at the time of extraction, and the adsorption tower is refilled by transportation means such as a truck. As described above, since it takes a lot of time and effort to reproduce, the reproduction is performed once a year or once every several months. Therefore, the amount of adsorbent used is large and the packed column must be large.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, eliminates the need to extract and transport from an adsorption tower, minimizes burning loss, and facilitates self-regeneration for regeneration work. The challenge is to provide a method.

[0004]

In order to solve the above problems, the present invention provides a method for adsorbing and purifying a pollutant gas and regenerating an adsorption tower having a reduced purifying function.
This is a method for self-regenerating an adsorption tower, which is characterized in that the step (c) is sequentially performed. (A) A step of introducing a gas whose temperature has been raised in a heat exchanger to an adsorption tower for desorption, (b) A step of introducing the desorbed gas from step (a) to a burner and burning it, (c) Combustion from step (b) A step of using gas as a heat source of the heat exchanger of step (a) and then dissipating it into the atmosphere.

In the regeneration method of the present invention, air, nitrogen or oxygen-removed air can be used as the gas to be heated in the heat exchanger in the step (a), and the temperature to be heated is determined by adsorption. The temperature is preferably higher than the temperature at which the substance is desorbed from the adsorbent, and the combustion gas used as the heat source of the heat exchanger in the step (c) is preferably released to the atmosphere after passing through the detoxification treatment device. . INDUSTRIAL APPLICABILITY The present invention utilizes a waste heat of a plant that produces harmful exhaust gas, particularly a combustion plant, can perform regeneration of an adsorbent on the spot, and is extremely efficient, energy-saving, and resource-saving that does not particularly need to limit a gas for heating Technology.

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an apparatus used in the reproducing method of the present invention. In FIG. 1, in the pollutant gas purification process, the pollutant gas 1 is introduced into the adsorption tower 3 through the inflow valve 2 and comes into contact with the adsorbent 4, whereby the pollutants in the gas are adsorbed and purified. The purified gas 6 passes through the outflow valve 5 and is opened to the atmosphere. Although FIG. 1 shows the case where one adsorption tower is provided, a plurality of adsorption towers may be provided. In the case of a plurality of columns, the pollutant gas may be flown in parallel to each column, or may be connected in series by the Merrigoland system. If the purifying process is continued, the adsorbent will break through, so the process proceeds to the regeneration process before the breakthrough.

To shift to the regeneration process, first, the valves 2 and 5 are closed and the fan 7 is operated. The gas source carrier gas 8 of the fan 7 may be air, oxygen-removed air, or an inert gas such as nitrogen. Depending on the type of adsorbent, if oxygen is mixed in the carrier gas, it may burn depending on the temperature condition. For example, when activated carbon is used as the adsorbent, a combustion reaction occurs when contacting the oxygen-containing gas at 300 to 400 ° C. or higher, so an inert gas must be used when regenerating above this temperature. As a method for easily obtaining an inert gas, there is a nitrogen generator by the PSA method. The carrier gas 8 is heated to an appropriate temperature in the heat exchanger 9. A suitable temperature is the minimum temperature for desorption of contaminants from the adsorbent. For example, a low boiling point substance such as tetrachloroethylene (hereinafter abbreviated as TCE), 200 ° C. is sufficient. When hydrogen sulfide or ammonia is a pollutant, the temperature is about 600 ° C.

The heated carrier gas 10 is introduced into the adsorption tower 3 through the valve 14 to raise the temperature of the adsorbent 4 and desorb pollutants from the adsorbent. (Desorption process (a)) The desorption gas 11 containing the desorbed substance is guided to the burner 12 through the valve 17. A fuel 13 such as propane or kerosene is introduced into the burner 12 through a valve 21, and air 15 can be blown by a fan 16 in case the amount of oxygen in the desorbed gas containing desorbed substances is insufficient. did. In this way, the burner 12 detoxifies the desorbed material by completely burning the desorbed material. The combustion temperature is a temperature necessary for detoxification, and a temperature at which secondary pollutants are not generated is good, and is generally 500 to 1200 ° C. (Combustion step (b)) The burner exhaust gas 18 is heat-exchanged by the heat exchanger 9, passes through the dust collector 19 and is released to the atmosphere as the detoxified gas 20 (exhaust step (c)).

Depending on the type of exhaust gas, it may not be possible to render it harmless only by complete combustion in the burner 12. In such a case, a detoxification device (not shown) for contacting the catalyst or the like can be provided before or after the heat exchanger. Generally, the adsorption tower 3 is rarely used as a single tower, and a plurality of towers are installed. Therefore, it is economical to carry out self-regeneration sequentially for each tower. In this case, even when the burner 12 cannot be detoxified only by complete combustion, no detoxification device is provided and the outlet gas of the dust collection device 19 is guided to the adjoining packed column 3 '(not shown). It may be possible to make it harmless.

[0010]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 An example of processing in which exhaust gas is adsorbed and regenerated by using two adsorption towers in parallel with the apparatus shown in FIG. The adsorption tower used had a diameter of 0.
Two columns of 6 m × 0.6 m in height were used, and the amount of activated carbon used was 50 liters per tower. Exhaust gas containing 130 ppm of TCE was passed through the adsorption tower at 200 Nm ³ / h to obtain a treated gas having TCE of 10 ppm or less.

The processing conditions at that time were as follows.

Comparative Example 1 A conventional method, that is, a method in which the adsorbent in the adsorption tower is taken out once every 60 days and regenerated in a regeneration plant to be filled, the same as in Example 1, the exhaust gas containing 130 ppm of TCE is 200 Nm.
The processing conditions for obtaining a processing gas having a TCE of 10 ppm or less through ³ / h were as follows. Treatment conditions Adsorption tower dimensions: Diameter 1.2m x Height 2.5m x 2 series Activated carbon usage: 1m ³ x 2 series SV: 200h ^-1 Regeneration is done at a regeneration plant, for adsorbent discharge and filling work. Took 6 hours.

As described above, the present invention requires a burner and a heat exchanger, but the adsorption tower can be smaller than the conventional method, the regeneration work can be very simple, and the conventional method can remove the mist. Although a drying machine is required as a pretreatment facility for the adsorption tower, in the present invention, since hot air is passed through the adsorption tower once a day, the drying machine was not required.

[0014]

According to the present invention, the following effects can be obtained. (A) Eliminate the trouble of extracting the adsorbent from the packed tower. (B) Eliminates the need for transportation means such as trucks. (C) Minimize baking loss. (D) Eliminating the trouble of recharging the adsorbent into the packed tower. (E) Since the regeneration frequency can be extremely increased, the amount of adsorbent used is small and the packed column can be made small.

(F) When the polluted gas contains a small amount of mist, pretreatment equipment such as a dryer can be omitted. (G) Since the burner exhaust gas is heat-recovered by the heat exchanger and used as the heat source of the temperature rising gas during the regeneration process, the heat recovery rate is good and the energy for the regeneration process can be minimized. (H) By adopting the heat exchanger, air, nitrogen, and oxygen-removed air can be freely selected as the temperature rising gas source during regeneration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus used in a reproducing method of the present invention.

[Explanation of symbols]

1: Contaminated gas, 2: Inflow valve: 3: Adsorption tower, 4: Adsorbent,
5: Outflow valve: 6: Purified gas: 7, 16: Fan, 8: Carrier gas, 9: Heat exchanger, 10: Temperature rising gas, 11: Desorption gas, 12: Burner, 13: Fuel, 14, 17:
Valve, 15: Air, 18: Burner exhaust gas, 19: Dust collector, 20: Exhaust gas, 21, 22: Valve

Claims (3)

[Claims] 1. A method for adsorbing and purifying polluted gas to regenerate an adsorption tower having a reduced purifying function, which comprises
A method for self-regenerating an adsorption tower, which comprises sequentially performing the step (c). (A) A step of introducing a gas whose temperature has been raised in a heat exchanger to an adsorption tower for desorption, (b) A step of introducing the desorbed gas from step (a) to a burner and burning it, (c) Combustion from step (b) A step of using gas as a heat source of the heat exchanger of step (a) and then dissipating it into the atmosphere. 2. The method for self-regenerating an adsorption tower according to claim 1, wherein the gas whose temperature is raised in the heat exchanger in step (a) is air, nitrogen or oxygen-removed air. 3. The adsorption tower according to claim 1 or 2, wherein the combustion gas used as the heat source of the heat exchanger in the step (c) is diffused into the atmosphere after passing through a detoxification treatment device. Self-renewal method.