JPS5834403B2 - How to regenerate activated carbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating activated carbon, and more particularly to a method for efficiently regenerating activated carbon by bringing it into contact with an alkanolamine.

Generally, activated carbon is regenerated by a roasting regeneration method, but when inorganic substances are adsorbed, the adsorption capacity cannot be recovered by roasting alone.

Therefore, it is necessary to provide an acid washing regeneration step and an alkali washing regeneration step together with the roasting regeneration step.

However, the alkaline cleaning process using caustic soda or the like requires an additional waste liquid treatment process, which has the disadvantage that the entire apparatus becomes complicated and expensive.

In order to eliminate the drawbacks of the conventional activated carbon regeneration method as described above, the inventor of the present invention has conducted various studies on alternative processes to the alkaline washing process using caustic soda, etc., and has achieved the objective by treating with alkanolamine. I found scales.

That is, the present invention involves (a) roasting the used activated carbon;
The present invention provides a method for regenerating active charcoal, which comprises b) acid washing, (C) contact with an alkanolamine, (d) roasting, and then Ke) acid washing.

Activated carbon that can be regenerated by the method of the present invention may be one that has been used in any process, and is not particularly limited as long as it has adsorbed organic substances such as oil and various inorganic substances.

For example, granular or spherical activated carbon used in wastewater treatment is a suitable target.

First, the roasting and regeneration step is mainly performed to incinerate and remove organic substances such as oil adsorbed on the used activated carbon.

This process is usually carried out in a regeneration furnace such as a rotary kiln or a vertical furnace at a temperature of 850'C to 1000C and for a time of 0.2 to 1.
It is done under the condition of time.

Next, the acid washing regeneration step is carried out mainly to remove oxides of calcium, magnesium, iron, etc. adsorbed on the activated carbon, and is usually carried out in an adsorption tower at room temperature.

The acid to be used is not particularly limited, but in general, hydrochloric acid with a concentration of 0.1 to 1% by weight is suitable, and it is preferably used in a ratio of 0.5 to 4 times the amount (volume ratio) of activated carbon.

The next step of cleaning and regeneration using alkanolamine is
This is mainly done to remove silicon oxides adsorbed on activated carbon, and is usually carried out in an adsorption tower at 30 to 4
Performed at 0°C.

In addition, as the alkanolamine used here, monoethanolamine (MEA), jetanolamine (D
EA), triethanolamine (TEA), methyldiethanolamine (MDEA), diisopropanolamine (DIPA), etc., and the concentration is 5 to 25%.
It is preferable to use it as a heavy aqueous solution.

Note that it is most preferable that the alkanolamine used in the above step is a new one from the viewpoint of regenerating activated carbon, but it may be an alkanolamine that is being used or has been used in the acid gas absorption process.

When using an alkanolamine currently in use in the acid gas absorption process, it is preferable to incorporate the activated carbon to be regenerated into the acid gas absorption process with the alkanolamine.

When activated carbon is incorporated into the above-mentioned acid gas absorption process, the silicon oxide in the activated carbon is transferred to alkanolamine due to the contact between the activated carbon and the alkanolamine, and at the same time, the regeneration of the activated carbon progresses, and at the same time, the alkanolamine The silicon oxide that has migrated into the system effectively prevents corrosion within the acid gas absorption process system.

In other words, silicon compounds are generally known to be effective in preventing corrosion in the system in acid gas absorption processes using alkanolamines, and in particular in gas absorption processes containing hydrogen sulfide. and corrosion protection in the acid gas absorption process system are achieved at the same time.
This is extremely convenient.

In addition, when the activated carbon after the roasting process and acid washing process is incorporated into the above acidic gas absorption process, the amine deterioration products and calcium, magnesium, iron oxides, etc. in the alkanolamine are adsorbed by the activated carbon, and the alkanolamine is regenerated. will also be carried out.

In the method of the present invention, when fresh alkanolamine is used in the alkanolamine washing and regeneration step, the activated carbon obtained by the treatment in this step is sufficiently regenerated and the adsorption capacity is almost restored to the state before use. When alkanolamines used in the acid gas absorption process are used, some amount of amine deterioration products and various metal oxides in the alkanolamines are adsorbed on activated carbon.
Regenerated activated carbon does not recover its adsorption capacity as quickly as when fresh alkanolamine is used.

Therefore, normally, after washing with alkanolamine, a roasting step and an acid washing step may be performed.

Here, the conditions for the roasting step and the acid washing step may be the same as those described above.

As mentioned above, according to the method of the present invention, the degree of regeneration of activated carbon is higher than that of the conventional method, and the CO of the obtained regenerated activated carbon is
The amount of D adsorption is recovered to the same level as new activated carbon.

Furthermore, if the method of the present invention is carried out on alkanolamines being used in an acidic gas absorption process, it is possible to regenerate activated carbon and at the same time prevent corrosion within the acidic gas absorption process system. It can also be expected to have the effect of significantly extending the life of the equipment.

Next, the method of the present invention will be explained in more detail with reference to Examples.

Example 1 The activated carbon tower 1 incorporated in the monoethanolamine acid gas absorption process as shown in FIG.
950℃ for 0.5 hours) and acid washing regeneration process (using 0.4% hydrochloric acid in 3 times the amount (volume ratio) of activated carbon) used activated carbon (used for wastewater treatment) Filled with 5,000 tons of granular activated carbon (diameter 12 to 40 mesh), and added 2000 tons of 15 weight multi-monoethanolamine aqueous solution.
The solution was passed for 48 hours at a rate of 00Kt per day.

After passing through the solution, the concentration of silicate in the monoethanolamine aqueous solution was measured by atomic absorption spectrometry, and the concentration increased from 25 to 50.

Furthermore, as a result of roasting and acid washing regeneration treatment of this activated carbon under the same conditions as above, it was confirmed that the adsorption capacity of the obtained activated carbon was recovered to the same level as the activated carbon before use.

[Brief explanation of the drawing]

FIG. 1 shows a series of apparatus incorporating an activated carbon column in a monoethanolamine acid gas absorption process. 1...Activated carbon tower, 2...Amine regeneration tower, 3...Regeneration tower receiving tank, 4...Amine regeneration tower reboiler, 5... ...Amine purifier, 6...
... Amine tank, 7 ... Circulating gas cleaning tower, 8
...Flash drum, 9...High pressure gas cleaning tower, 10...Flash tank, 11.
...Low pressure gas cleaning tower.

Claims (1)

[Claims] 1. Used activated carbon is (a) roasted, (b) acid washed,
A method for regenerating activated carbon, which comprises (C) contacting with an alkanolamine, (d) roasting, and then Ke) acid washing. 2. The method for regenerating activated carbon according to claim 1, wherein the alkanolamine is an aqueous solution having a concentration of 5 to 25% by weight.