JPH09234334A - Hydrogen sulfide desulfurization apparatus and desulfurization of hydrogen sulfide-containing gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate the propagation of thermophilic/acidophilic sulfur oxidizing bacteria in a bacteria treatment tank and to dispense with a propagation process for supplying bacterial cells. SOLUTION: Hydrogen sulfide-containing gas is passed through a desulfurization apparatus equipped with a bacteria treatment tank 3 fillid with a desulfurizing soln. 2 containing thermophilic/acidophilic sulfur oxidizing bacteria and a bacterial cell recovery filter to be desulfurized by converting hydrogen sulfide to sulfuric acid by the action of thermophilic/acidophilic sulfur oxidizing bacteria and the exhaust gas reduced in the concn. of hydrogen sulfide is discharged and a sulfuric acid-containing soln. is drawn out while the same amt. of a desulfurizing soln. 9 is supplied to continuously perform desulfurization. In this case, a yeast extract 13 is continuously added to the desulfurizing soln. 9 supplied to the bacteria treatment tank 3 and desulfurization in the bacteria treatment tank 3 is performed in the presence of the yeast extract 13.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a desulfurization apparatus for hydrogen sulfide using microorganisms and a desulfurization method for hydrogen sulfide-containing gas using the same, and particularly to desulfurization suitable for desulfurization of hydrogen sulfide-containing gas generated in a geothermal power plant. The present invention relates to an apparatus and a desulfurization method using the apparatus.

[0002]

2. Description of the Related Art A gas containing a high concentration of hydrogen sulfide is generated in a geothermal power plant. As one of the methods for treating the hydrogen sulfide-containing gas, the hydrogen sulfide-containing gas generated in a geothermal power plant is introduced into a microbial treatment tank using a high-temperature / sulfur-acid-oxidizing microorganism for desulfurization treatment, and the sulfuric acid generated by the desulfurization is generated. Efficient desulfurization can be performed by adding the culture solution of the microbial treatment tank that has been acidified by the hot water returned to the reduction well, and the pH of the hot water returned to the reduction well increases There is a desulfurization method using microorganisms that can prevent clogging.

The outline of the desulfurization method will be described with reference to FIG. At a geothermal power plant (not shown), a high-concentration hydrogen sulfide-containing non-condensing gas 1 is filled with a desulfurization liquid 2 (temperature 70 ° C., pH 2.5, sulfuric acid acidity) containing sulfur-oxidizing microorganisms, which is a bubble column type microbial treatment. It is introduced into the tank 3 together with air or oxygen 4. In the high-concentration hydrogen sulfide-containing non-condensable gas 1, hydrogen sulfide in the gas is oxidized in the microbial treatment tank 3 to become a low-concentration hydrogen sulfide-containing non-condensed gas 5, which is released to the atmosphere. Microbial treatment tank 3
One of the genus Sulfolobus is used as the microorganism. The pH of the desulfurization liquid 2 in the microorganism treatment tank 3 decreases with time as hydrogen sulfide is oxidized and converted into an acid containing sulfur. The desulfurization liquid 2 that has been acidified with the production of sulfuric acid is extracted from the microbial treatment tank 3 as acidic water 7 through the microbial cell separation filter 6, and at the same time, the concentrated microbial cells 8 are returned to the microbial treatment tank 3. The acidic water 7 thus obtained is injected into a reduction well (not shown), whereby the pH of the hot water is lowered and clogging of the reduction well due to scale adhesion is reduced. On the other hand, a new desulfurization liquid 9 in the same amount as the extracted acidic water 7 is desulfurization liquid tank 10.
From the above, both the bacterial cells 16 grown in the growth culture tank 14 are introduced into the microorganism treatment tank 3 by the bacterial cell supply pump 15, and desulfurization is continuously performed. The amount of microbial cells is kept above a certain level in the microbial treatment tank 3 by the collection by the microbial cell separation filter 6 and the introduction of the microbial cells from the growth culture tank 14.

[0004]

There are the following two methods for growing high-temperature, sulfurous acid-oxidizing microorganisms used in the above method. One is heterotrophic growth, which is a separate growth tank as shown in FIG. 2, which grows by utilizing organic matter, and the other is autotrophic growth by hydrogen sulfide oxidation that occurs in the microorganism treatment tank. . In the above-mentioned conventional technique, the amount of growth in the microbial treatment tank is smaller than the amount diluted with the desulfurization liquid, and the desulfurization liquid is diluted, so that the bacterial cells are reduced and the desulfurization rate decreases with time. Therefore, a growth tank for supplementing the bacterial cells is required, and the cost for supplying the growth liquid from the bacterial cell growth tank has been a problem.

The present invention solves the above-mentioned problems in the prior art, can promote the growth of high-temperature / acid-acid sulfur-oxidizing microorganisms in a microorganism treatment tank, and does not require a growth step for supplementing the cells. An object is to provide a hydrodesulfurization apparatus and a desulfurization method using the same.

[0006]

The present invention includes (1) high temperature
A microbial treatment tank filled with a desulfurization liquid containing a sulphate-oxidizing microorganism and a microbial cell recovery filter are provided, and desulfurization is performed by converting hydrogen sulfide to sulfuric acid by passing a hydrogen sulfide-containing gas through the microbial treatment tank to obtain a concentration of hydrogen sulfide. In a device that performs desulfurization continuously by discharging reduced exhaust gas, extracting a solution containing sulfuric acid, and replenishing the same amount of desulfurization liquid, yeast extract is continuously added to the desulfurization liquid to be added to the microbial treatment tank. A hydrogen sulfide desulfurization device characterized by comprising a pump for addition and a yeast extract tank, and (2) high temperature
Hydrogen sulfide-containing gas is passed through a desulfurization device equipped with a microbial treatment tank filled with a desulfurization liquid containing sulfur-acid-oxidizing microorganisms and a cell recovery filter, and hydrogen sulfide is converted to sulfuric acid by the action of high-temperature sulfur-oxidizing microorganisms oxidizing sulfur. In this desulfurization method, in which desulfurization is performed, exhaust gas with reduced hydrogen sulfide concentration is discharged, and a solution containing sulfuric acid is extracted and the same amount of desulfurization solution is replenished to continuously desulfurize the microbial treatment tank. Yeast extract is continuously added to the desulfurizing solution, and desulfurization is performed in the microorganism treatment tank in the presence of the yeast extract.

The amount of yeast extract added to the desulfurization solution in the desulfurization method of the above (2) is 0.00 relative to the desulfurization solution.
It is preferably set to 01% or more.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The addition of yeast extract increases the acid conversion rate in the microbial treatment tank and enables highly efficient sulfuric acid production. Since the growth of high-temperature / acid-sulfuric acid-oxidizing microorganisms is linked to the production of sulfuric acid, the growth amount in the microbial treatment tank becomes larger than the dilution amount of the desulfurization solution, and the bacterial concentration required for desulfurization treatment can be maintained. .

The present invention will be described below with reference to the drawings.
FIG. 1 is a schematic flow chart showing one embodiment of the apparatus of the present invention. In FIG. 1, a high-concentration hydrogen sulfide-containing non-condensing gas 1 (usually containing 1 to 2% hydrogen sulfide) generated in a geothermal power plant (not shown) is a desulfurization liquid 2 containing a high temperature sulfur oxyacid-oxidizing microorganism. It is introduced together with air or oxygen 4 into the filled bubble column type microbial desulfurization tank 3. The desulfurization liquid 2 has a temperature of 50 to 9
At 0 ° C., preferably 60 to 80 ° C., pH 3 or less, preferably 1 to 2.5, sulfuric acid acidity, and an appropriate amount of high temperature / acid-acid sulfur-oxidizing microorganisms are contained, and yeast extract tank 11 to yeast extract 13 It is added and supplied to the microbial desulfurization tank 3.

The high-concentration hydrogen sulfide-containing non-condensable gas 1 is a low-concentration hydrogen sulfide-containing non-condensing gas in which the hydrogen sulfide in the gas is oxidized in the microbial treatment tank 3 by the action of the high temperature sulfur oxyacid-oxidizing microorganisms and removed as sulfuric acid. It becomes 5 and is released to the atmosphere. 50 to 90 for high temperature and sulphate-oxidizing microorganisms in the microbial desulfurization tank 3.
It is a microorganism that oxidizes hydrogen sulfide and sulfur in an acidic range of pH 3 or less at a high temperature of ℃ and finally produces sulfuric acid. A preferred example of this microorganism is Sulfolobus.
) Microorganisms of the genus.

The pH of the desulfurization liquid 2 in the microorganism treatment tank 3 decreases with time as hydrogen sulfide is oxidized and converted into an acid (sulfuric acid) containing sulfur. Desulfurization liquor acidified with sulfuric acid production 2
Is extracted from the microbial treatment tank 3 through the microbial cell separation filter 6 as acidic water 7, and at the same time, the microbial cells 8 are returned to the microbial treatment tank 3. Acidic water 7 extracted in this way
Is injected into the reduction well (not shown),
H is lowered, and blockage of the reduction well due to scale adhesion is reduced.

On the other hand, the same amount of fresh desulfurization liquid 9 as the extracted acidic water 7 is introduced into the microorganism treatment tank 3 from the desulfurization liquid tank 10. At the same time, the yeast extract 13 is added from the yeast extract tank 11 to the microbial treatment tank 3 by the yeast extract pump 12 so as to be 0.0001% of the desulfurization solution.
Yeast extract is a source of essential amino acids (such as methionine) and vitamins for the activity of microorganisms,
Specifically, Difco's Bacto yeast extract (Difco
Company: Bacto Yeast Extract) and the like can be used. By adding the yeast extract, the high temperature / sulfurous acid-oxidizing microorganisms in the microorganism treatment tank 3 can be propagated with high efficiency by autotrophic growth, and the recovery by the filter 6 and the microorganism treatment tank 3 can be performed.
Due to the highly efficient growth therein, the amount of bacterial cells is kept above a certain level in the microorganism treatment tank 3. As a result, it becomes possible to perform desulfurization treatment continuously with high efficiency.

The microbial cell concentration in the microorganism treatment tank 3 is 1 × 10 ⁹
cells / ml or more, preferably 2 × 10 ⁹
It is about cells / milliliter.

[0014]

[Examples] The effects of adding yeast extract will be described below with reference to Examples. Under the conditions shown in Table 1, an acid conversion test of hydrogen sulfide was conducted by changing the yeast extract concentration in the microorganism treatment tank.
The results are shown in Fig. 3, where the yeast extract concentration was 0.00
When it is less than 01%, the acid conversion rate becomes small. That is, the amount of sulfuric acid produced is small, so that sufficient growth cannot be achieved. Therefore, the yeast extract concentration needs to be 0.0001% or more.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Effects of the Invention] By adding yeast extract to the microorganism treatment tank, it becomes possible to highly efficiently autotrophically grow high-temperature, sulfurous acid-oxidizing microorganisms in the microorganism treatment tank, and to keep the bacterial cell concentration above the required concentration. it can. Therefore, continuous production of acidic water (desulfurization treatment) without supplementation of bacterial cells from the culture tank for growth
Becomes possible. As a result, it is not necessary to supply the bacterial cells from the culture tank for growth, and the cost of the bacterial cell growth liquid is reduced.

[Brief description of drawings]

FIG. 1 is a flow chart of a biodesulfurization device for a geothermal power plant according to an embodiment of the present invention.

FIG. 2 is a flow diagram of a conventional geothermal power plant biodesulfurization apparatus.

FIG. 3 is a graph showing the relationship between yeast extract concentration and acid conversion rate.

Claims (3)

[Claims] 1. A microbial treatment tank filled with a desulfurization liquid containing a high temperature sulfurous acid-oxidizing microorganism and a microbial cell recovery filter,
Desulfurization is performed by converting hydrogen sulfide into sulfuric acid by passing a hydrogen sulfide-containing gas through the microorganism treatment tank to discharge exhaust gas having a reduced hydrogen sulfide concentration, and a solution containing sulfuric acid is extracted and the same amount of desulfurization liquid is replenished. Thus, in a device for continuously desulfurizing, a hydrogen sulfide desulfurization device comprising a pump and a yeast extract tank for continuously adding a yeast extract to a desulfurization liquid to be replenished in a microorganism treatment tank. 2. A desulfurization apparatus equipped with a microbial treatment tank filled with a desulfurization liquid containing a high-temperature / sulfur-acid-acid-oxidizing microorganism and a microbial cell recovery filter is passed through a gas containing hydrogen sulfide to cause the action of the high-temperature / sulfur-acid-oxidizing microorganism. A desulfurization method in which desulfurization is performed by converting hydrogen sulfide to sulfuric acid, exhaust gas with reduced hydrogen sulfide concentration is discharged, and a solution containing sulfuric acid is extracted, and desulfurization liquid of the same amount is replenished for continuous desulfurization. In the method for desulfurization of hydrogen sulfide-containing gas, yeast extract is continuously added to a desulfurization liquid to be replenished in the microorganism treatment tank, and desulfurization in the microorganism treatment tank is performed in the presence of the yeast extract. 3. The method for desulfurizing a hydrogen sulfide-containing gas according to claim 2, wherein the amount of yeast extract added to the desulfurization solution is 0.0001% or more based on the desulfurization solution.