JP2010022965A - Desulfurization method and apparatus for digestive gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a desulfurization method and an apparatus for desulfurizing digestive gas capable of appropriately diluting hydrogen sulfide without restriction even when an amount of hydrogen sulfide contained in the digestive gas becomes much, capable of performing efficient desulfurization, not only not requiring measurement of concentration of hydrogen sulfide and oxygen and control of a feeding amount of the oxygen in order to prevent explosion but also capable of miniaturizing a removal treatment part of hydrogen sulfide. <P>SOLUTION: The desulfurization apparatus for the digestive gas includes an absorption column 4 for separating carbon dioxide and hydrogen sulfide from the digestive gas and refining methane, a pressure reduction tank 11 and a diffusion column 12 as a separation means for pressure-reducing high pressure water dissolved with carbon dioxide and hydrogen sulfide taken out from the absorption column 4 and separating the carbon dioxide and the hydrogen sulfide, and an organism desulfurization column 16 having a filling material layer 15 for receiving the separated carbon dioxide and hydrogen sulfide and air 14 as an oxygen-containing gas and deposited with micro-organism for decomposing the hydrogen sulfide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digestion gas desulfurization method and apparatus for removing hydrogen sulfide contained in digestion gas generated by subjecting organic waste to methane fermentation.

  Currently, methane fermentation treatment is frequently used to treat organic waste with relatively high water content. The gas generated by this methane fermentation treatment is usually called “digestion gas”, and the components in the digestion gas are about 60% by volume of methane and about 40% by volume of carbon dioxide. Furthermore, 100 to 3000 ppm of hydrogen sulfide is usually contained as an impurity. This digestion gas is used as a fuel gas. For example, it is a fuel such as a boiler for producing hot water or steam, such as a gas engine for power generation, a gas turbine, or a fuel cell. However, if hydrogen sulfide is mixed in the digestion gas, sulfur oxides are generated by combustion. Therefore, in any application, mechanical parts such as engines are corroded or the concentration of sulfur oxides in exhaust gas is reduced. The problem of getting higher occurs. Therefore, it is necessary to use after reducing hydrogen sulfide. As a technique for reducing this hydrogen sulfide, a technique described in Patent Document 1 is known.

The technique for reducing hydrogen sulfide disclosed in Patent Document 1 is as follows.
1) Air is supplied from the air supply means to the digestion gas before being introduced into the reaction tower of a desulfurization apparatus having a reaction tower filled with a filler to which microorganisms adhere.
2) Digestion gas and water supplied with air are introduced into the reaction tower to remove hydrogen sulfide in the digestion gas (desulfurization).
3) The concentration of hydrogen sulfide and oxygen in the digestion gas discharged from the reaction tower after desulfurization is measured, and the concentration of oxygen in the air supplied from the air supply means is controlled based on these measurement results.
JP 2003-305328 A

  However, the technique for reducing hydrogen sulfide disclosed in Patent Document 1 has the following problems.

1) Air is added directly to digestion gas containing methane (ie, oxygen will be added directly to methane). Therefore, there is a risk of explosion if oxygen is mixed in a predetermined concentration or more with respect to methane in the digestion gas. Therefore, it is necessary to control the supply amount of oxygen by measuring the concentration of hydrogen sulfide and oxygen.
2) In addition, as described above, since oxygen may explode when mixed at a predetermined concentration or more, even if the amount of hydrogen sulfide introduced into the reaction tower becomes so large as to reduce the desulfurization efficiency, it is diluted. A large amount of oxygen cannot be added appropriately. This becomes a big problem when the amount of hydrogen sulfide contained in the digestion gas increases.
3) Further, since digestion gas containing about 60% by volume of methane is supplied to the reaction tower, there is a problem that the reaction tower must be made large.
4) Furthermore, since a large amount (about 40% by volume) of carbon dioxide and other impurities remain in the desulfurized digestion gas, there is a problem that the amount of heat as a fuel is insufficient and the equipment used is limited.

  The purpose of the present invention is to remove hydrogen sulfide in digestion gas generated by methane fermentation of organic substances such as food waste and sewage sludge. An object of the present invention is to provide a digestion gas desulfurization method and apparatus that can eliminate the need for severe control of the supply amount, make the hydrogen sulfide removal treatment section compact, and obtain high-quality methane gas.

In order to achieve this object, the invention according to claim 1 of the present invention provides:
The digestion gas generated by subjecting the organic waste to methane fermentation is compressed by a compressor and pressurized, the digested gas pressurized is supplied to an absorption tower, and the digestion gas and water whose pressure is increased in the absorption tower In a high-pressure state, carbon dioxide and hydrogen sulfide contained in the pressurized digestion gas are dissolved in high-pressure water, and the carbon dioxide and hydrogen sulfide are separated from the pressurized digestion gas. A purification step;
The high-pressure water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved is decompressed, and the carbon dioxide and hydrogen sulfide are extracted from the water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved. Separating the
The separated carbon dioxide, hydrogen sulfide, and oxygen-containing gas are supplied to a biological desulfurization tower having a filler layer to which microorganisms that decompose hydrogen sulfide are attached, and hydrogen sulfide in the mixed gas is utilized using the action of the microorganisms. Disassembling, and
A digestion gas desulfurization method characterized by comprising:

The invention according to claim 2 is the invention according to claim 1,
The high-pressure water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved is supplied to the biological desulfurization tower, and the carbon dioxide and hydrogen sulfide bubbles generated from the high-pressure water are contained in the biological desulfurization tower. It has the process of wash | cleaning a filler layer.

The invention according to claim 3 is the invention according to claim 1 or 2,
It has the process of heating the said biological desulfurization tower using the heat | fever which generate | occur | produces from the said compressor.

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
In order to keep the concentration of hydrogen sulfide in the mixed gas supplied to the biological desulfurization tower at a predetermined value, the concentration of hydrogen sulfide in the digestion gas is measured, and according to the measured concentration of hydrogen sulfide, the oxygen It has the process of controlling the quantity of the said oxygen containing gas supplied from a containing gas supply means.

The invention described in claim 5
The compressor that compresses and pressurizes digestion gas generated by methane fermentation of organic waste, and the digestion gas and water that have been pressurized by the compressor are received and brought into contact with each other in a high-pressure state, thereby increasing the pressure. The carbon dioxide and hydrogen sulfide contained in the digestion gas are dissolved in high-pressure water to separate the carbon dioxide and hydrogen sulfide from the pressurized digestion gas, and an absorption tower for purifying methane, and an extraction from the absorption tower Separating means for depressurizing the high-pressure water in which the carbon dioxide and hydrogen sulfide dissolved are separated to separate the carbon dioxide and hydrogen sulfide extracted from the water in which the carbon dioxide and hydrogen sulfide are extracted from the absorption tower; A biological desulfurization tower having a filler layer that receives the separated carbon dioxide, hydrogen sulfide, and oxygen-containing gas and has microorganisms that decompose the hydrogen sulfide attached thereto. It is desulfurizer biogas characterized.

The invention according to claim 6 is the invention according to claim 5,
In order to clean the filler layer in the biological desulfurization tower with bubbles of the carbon dioxide and hydrogen sulfide in the high-pressure water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved, High pressure water supply means for supplying to the biological desulfurization tower is provided.

The invention according to claim 7 is the invention according to claim 5 or 6,
A recovery means for recovering heat generated from the compressor, and a heat retaining means for warming the biological desulfurization tower using the heat recovered by the recovery means are provided.

The invention according to claim 8 is the invention according to any one of claims 5 to 7,
In order to keep the hydrogen sulfide concentration in the mixed gas supplied to the biological desulfurization tower at a predetermined value, the hydrogen sulfide concentration meter for measuring the concentration of hydrogen sulfide in the digestion gas and the hydrogen sulfide concentration meter were used. Control means for controlling the amount of the oxygen-containing gas supplied from the oxygen-containing gas supply means according to the concentration of hydrogen sulfide.

As described above, according to the digestion gas desulfurization method of the present invention,
The digestion gas generated by subjecting the organic waste to methane fermentation is compressed by a compressor and pressurized, the digested gas pressurized is supplied to an absorption tower, and the digestion gas and water whose pressure is increased in the absorption tower And the carbon dioxide and hydrogen sulfide contained in the pressurized digestion gas are dissolved in high pressure water to separate the carbon dioxide and hydrogen sulfide from the pressurized digestion gas, A purification step;
The high-pressure water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved is decompressed, and the carbon dioxide and hydrogen sulfide are extracted from the water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved. Separating the
The separated carbon dioxide, hydrogen sulfide, and oxygen-containing gas are supplied to a biological desulfurization tower having a filler layer to which microorganisms that decompose hydrogen sulfide are attached, and hydrogen sulfide in the mixed gas is utilized using the action of the microorganisms. Disassembling, and
Therefore, the following effects are achieved.
1) Almost no methane is contained in the gas before the oxygen-containing gas such as air is mixed in advance, which eliminates the need for hydrogen sulfide and oxygen concentration measurement and oxygen supply control to prevent explosions. In addition, even when the amount of hydrogen sulfide contained in the gas is increased, it is possible to dilute hydrogen sulfide as appropriate without restriction. Therefore, the gas can be efficiently desulfurized while the facility is simplified.
2) As described in 1) above, the gas supplied to the biological desulfurization tower contains almost no methane. Therefore, a digestion gas desulfurization method in which the biological desulfurization tower as a hydrogen sulfide removal treatment unit is made compact is used. realizable.
3) According to the digestion gas desulfurization method of the present invention, not only desulfurization is possible, but also efficient methane purification can be realized.

Moreover, according to the digestion gas desulfurization apparatus according to the present invention,
The compressor that compresses and pressurizes digestion gas generated by methane fermentation of organic waste, and the digestion gas and water that have been pressurized by the compressor are received and brought into contact with each other in a high-pressure state, thereby increasing the pressure. The carbon dioxide and hydrogen sulfide contained in the digestion gas are dissolved in high-pressure water to separate the carbon dioxide and hydrogen sulfide from the pressurized digestion gas, and an absorption tower for purifying methane, and an extraction from the absorption tower Separating means for depressurizing the high-pressure water in which the carbon dioxide and hydrogen sulfide dissolved are separated to separate the carbon dioxide and hydrogen sulfide extracted from the water in which the carbon dioxide and hydrogen sulfide are extracted from the absorption tower; A biological desulfurization tower having a filler layer that receives the separated carbon dioxide, hydrogen sulfide, and oxygen-containing gas and has microorganisms that decompose the hydrogen sulfide attached thereto. Because you are, provide the following operational effects.
1) Since the gas before the oxygen-containing gas such as air is mixed with almost no methane in advance, the hydrogen sulfide and oxygen concentration meter for preventing explosion and the control to control the supply amount of oxygen It is possible to dilute the hydrogen sulfide as appropriate without restriction even when the means becomes unnecessary and the amount of hydrogen sulfide contained in the gas increases. Therefore, the facility can be simplified despite efficient gas desulfurization.
2) The gas supplied to the biological desulfurization tower contains almost no methane as described in 1) above. Therefore, a digestion gas desulfurization apparatus in which the biological desulfurization tower as a hydrogen sulfide removal treatment unit is made compact is provided. realizable.
3) According to the digestion gas desulfurization apparatus according to the present invention, it is possible to realize a digestion gas desulfurization apparatus that allows not only desulfurization but also efficient purification of methane.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram schematically illustrating the overall configuration of a digestion gas desulfurization apparatus according to an embodiment of the present invention.

  First, the configuration of a digestion gas desulfurization apparatus according to the present invention will be described.

  In FIG. 1, 1 is a mist separator, 2 is a hydrogen sulfide concentration meter for measuring the concentration of hydrogen sulfide in digested gas that has passed through the mist separator 1, 3a and 3b are gas compressors, and 4 is an absorption tower (scrubber). 5 is a dehumidifier, 6 is a water supply tank, 7 is a water supply pump, 8 is a water circulation pump, 9 is a heat exchanger, 10 is a chiller, 11 is a decompression tank (flushing tank), 12 is a stripping tower (stripping) (Tower), 13 is a blower as an oxygen-containing gas supply means, 14 is air, 15 is a filler layer to which aerobic sulfur-oxidizing bacteria mainly consisting of thiobacillus bacteria are attached as microorganisms, and 16 includes a filler layer 15. It is a biological desulfurization tower.

  Next, the operation of the digestion gas desulfurization apparatus according to the present invention will be described with reference to FIG.

Digestion gas generated by subjecting organic waste such as organic sludge and organic wastewater to methane fermentation has mist (moisture) and dust in the digestion gas removed by the mist separator 1. The components in the digestion gas after passing through the mist separator 1 are about 60% by volume of methane (CH ₄ ), about 40% by volume of carbon dioxide (CO ₂ ), 100 to 3000 ppm of hydrogen sulfide (H ₂ S), Trace amounts of other impurities. The digestion gas is compressed by gas compressors 3a and 3b connected in series, and the pressure is increased to a predetermined pressure higher than the atmospheric pressure. The digestion gas pressurized by the gas compressors 3 a and 3 b is introduced into the lower part of the absorption tower 4. On the other hand, water is supplied to the absorption tower 4 in a state where the pressure is increased by the water circulation pump 8 from above.

  Thus, by increasing the digestion gas by the gas compressors 3a, 3b and feeding it from the lower part into the absorption tower 4, and by boosting the water by the water circulation pump 8 and feeding it from the upper part to the absorption tower 4, The inside of the absorption tower 4 is maintained in a high pressure state satisfying the range of 0.55 to 2.0 MPaG, and the digestion gas and water are brought into contact with each other in the high pressure state satisfying the pressure range in the absorption tower 4. The absorption tower 4 is filled with a packing such as Raschig ring in order to bring the digestion gas and water into sufficient contact.

  By contacting the digestion gas and water in the absorption tower 4 in a high pressure state satisfying the range of 0.55 to 2.0 MPaG, the carbon dioxide and hydrogen sulfide contained in the digestion gas in a gaseous state are in a high pressure state. While dissolved in water and absorbed, methane is taken from the top of the absorption tower 4 with almost no dissolution in high pressure water. The purified gas having a high concentration of methane taken out from the top of the absorption tower 4 is sent to the dehumidifier 5 and has sufficient moisture so that no condensation occurs even at the pressure when used (utilized) as fuel. Is removed by adsorption. Moreover, when purifying methane by separating carbon dioxide and hydrogen sulfide from the digestion gas, the digestion gas and water are preferably brought into contact with each other in a high pressure state satisfying a range of 0.55 to 2.0 MPaG. Carbon dioxide, hydrogen sulfide, etc. are not sufficiently separated and removed in an atmosphere at a pressure lower than this range, and the removal rate of carbon dioxide and hydrogen sulfide is not improved so much even in an atmosphere at a pressure higher than this range. In view of the increase in equipment cost due to high pressure specifications, it is not preferable. In addition, it is more preferable to make digestion gas and water contact in the high pressure state which satisfy | fills the range of 0.7 MPaG or more and less than 1.0 MPaG from the point of a removal rate, an operating cost, and apparatus cost.

  When the digestion gas contains a siloxane compound by bringing the digestion gas and water into contact with each other at a high pressure of 0.55 MPaG or more as described above, the siloxane compound is condensed and separated from the gas. Few siloxane compounds remain in the purified gas with a high concentration of methane removed from the top of the tank. Therefore, since high-calorie and high-purity methane gas can be obtained, it can be used for gas engine power generation facilities, natural gas vehicles, and the like.

  Next, the high-pressure water in which carbon dioxide and hydrogen sulfide separated from the digestion gas are dissolved is extracted from the bottom of the absorption tower 4 and introduced into the decompression tank 11 through the valve V1. The pressure in the decompression tank 11 is reduced compared to that in the absorption tower 4. For example, when the pressure in the absorption tower 4 is 0.9 MPaG, the pressure in the decompression tank 11 is 0.3 MPaG. For the purpose of increasing the methane recovery rate, methane that is slightly dissolved in the high-pressure water from the bottom of the absorption tower 4 is separated as a gas and is gas-compressed from the top of the decompression tank 11 through the valve V12 to the gas compressor 3a. 3b is returned to the intermediate stage of 3b and joined to the digestion gas from the gas compressor 3a. The water in which carbon dioxide and hydrogen sulfide are dissolved after the methane is separated and recovered is introduced from the bottom of the decompression tank 11 to the upper portion of the stripping tower 12 through the valve V3.

  In this stripping tower 12, water extracted from the decompression tank 11 is introduced from the upper part and depressurized to about atmospheric pressure, and from the lower part, the stripping gas (for example, air 14) is substantially the same as the carbon dioxide by the blower 13. Supplied to have the same volume. By reducing the pressure to about atmospheric pressure and the air 14, the carbon dioxide and hydrogen sulfide dissolved in the water extracted from the decompression tank 11 are separated from the water, and the separated carbon dioxide is further separated in the diffusion tower 12. Carbon and hydrogen sulfide are mixed with air 14, and a mixed gas composed of the mixed carbon dioxide, hydrogen sulfide, and air 14 is introduced into the upper portion of the biological desulfurization tower 16. In addition, air is simple as the gas for diffusion, but is not necessarily limited thereto, and various gases containing oxygen (hereinafter referred to as “oxygen-containing gas”) can be used. is there. Thus, oxygen-containing gas including air may be supplied using oxygen-containing gas supply means such as the blower 13.

  Further, the water from which carbon dioxide and hydrogen sulfide have been expelled is extracted from the bottom of the stripping tower 12, pressurized by the water circulation pump 8, and heat exchanged with the brine from the chiller 10 by the heat exchanger 9. Then, after being cooled to a predetermined temperature (for example, 7 ° C.), it is supplied to the upper part of the absorption tower 4. The diffusion tower 12 is filled with a packing such as Raschig ring in order to bring the air 14 and water into sufficient contact.

  Moreover, as the water introduced from the upper part of the biological desulfurization tower 16, the water stored in the water tank 6 or the waste water discharged from the valve V4 can be used. Moreover, when using warm water as water introduced from the upper part of the biological desulfurization tower 16, since the action | operation of the sulfur oxidation bacteria in the biological desulfurization tower 16 mentioned later becomes active by providing the following structures, More preferred. For example, warm water (for example, 30 to 50 ° C.) is produced by heat generated from the compressors 3 a and 3 b, and the warm water is introduced from the upper part of the biological desulfurization tower 16. Specifically, water used for cooling the compressors 3 a and 3 b is introduced from the upper part of the biological desulfurization tower 16. Further, it is preferable to recover the heat generated from the compressors 3a and 3b and warm the biological desulfurization tower 16 using the recovered heat. That is, a cooling means (not shown) for cooling the heat generated from the compressors 3a and 3b with water is provided close to the compressors 3a and 3b. And the heat retention means (not shown) provided in the vicinity of the biological desulfurization tower 16 from the recovery means (not shown) which collected the warm water (for example, 50 ° C. to 60 ° C.) after being cooled by the cooling means. The warm water is heated to about 37 ° C. so that the action of sulfur-oxidizing bacteria in the biological desulfurization tower 16 becomes most active.

Next, a process of decomposing (desulfurizing) hydrogen sulfide in a mixed gas composed of carbon dioxide, hydrogen sulfide, air 14 and the like in the biological desulfurization tower 16 will be described. By passing the mixed gas and water introduced from the upper part of the biological desulfurization tower 16 through the filler layer 15 to which aerobic sulfur-oxidizing bacteria mainly including Thiobacillus bacteria are attached, the aerobic sulfur-oxidizing bacteria can function. Utilizing it, hydrogen sulfide (H ₂ S) is oxidized and decomposed to change to sulfur (S). Furthermore, this sulfur (S) is oxidized and changed to SO ₄ ²⁻ . Through such a process, hydrogen sulfide is finally decomposed and removed from the digestion gas (desulfurization is completed).

  In the biological desulfurization tower 16, since desulfurization is stably performed when the concentration of hydrogen sulfide is constant and efficiency is improved, it is more preferable to provide the following mechanism as in this embodiment. That is, a hydrogen sulfide concentration meter 2 for measuring the concentration of hydrogen sulfide in the digestion gas is provided at a location that has passed through the mist separator 1, and the concentration of hydrogen sulfide in the mixed gas introduced into the biological desulfurization tower 16 is substantially reduced. The amount of air 14 supplied from the blower 13 is controlled by a control means (not shown) according to the measured concentration of hydrogen sulfide so as to keep constant.

In the above desulfurization process, hydrogen sulfide (H ₂ S) is oxidatively decomposed, and changed sulfur (S) tends to adhere to the filler layer 15. Therefore, it is more preferable to provide the following mechanism as in this embodiment. That is, sulfur (S) adhering to the filler layer 15 in the biological desulfurization tower 16 is washed with bubbles generated by foaming of carbon dioxide and hydrogen sulfide in high-pressure water in which carbon dioxide and hydrogen sulfide extracted from the absorption tower 4 are dissolved. In order to achieve this, high-pressure water supply means (not shown) for supplying this high-pressure water to the biological desulfurization tower 16 may be provided. In this way, the deposit is washed with the bubble-containing water generated by foaming from the high-pressure water, and the deposit composed of peeled sulfur (S) and the like is drained through the valve V8 together with the water containing SO ₄ ^2-. Is done. The mixed gas from which hydrogen sulfide (H ₂ S) has been decomposed and removed is exhausted through the valve V7. Specifically, the cleaning of the filler layer 15 with the high-pressure water is performed by filling the filler layer 15 with water and then supplying high-pressure water from the bottom of the filler layer 15 and cleaning with bubbles, or by using high-pressure water. Is preferably supplied from under the filler layer 15 and filled with water while the filler layer 15 is washed with bubbles.

  Moreover, in order to maintain the quality of the circulating water supplied to the absorption tower 4, it is desirable to open the valve V4 regularly. Thereby, a part of the circulating water is extracted, and the extracted water is drained. When the amount of circulating water falls below a predetermined amount due to this extraction, the water replenishment pump 7 opens the valve V5 and replenishes the insufficient amount of water from the water supply tank 6. As water used at this time, it is also possible to use treated water obtained by treating drainage water such as tap water, well water, or sewage. In this embodiment, the final sedimentation basin of the sewage treatment plant is used. Sand filtration water from a sand filtration facility for treated water provided downstream is used.

  Moreover, in this embodiment, although the example of the water stored in the water supply tank 6 was demonstrated as water introduce | transduced from the upper part of the biological desulfurization tower 16, it is not necessarily limited to this. For example, waste water discharged from the valve V4 may be introduced from the upper part of the biological desulfurization tower 16. Moreover, you may introduce | transduce the water (for example, 30-50 degreeC) utilized for cooling of the compressors 3a and 3b from the upper part of the biological desulfurization tower 16. FIG.

  Further, in the present embodiment, carbon dioxide and hydrogen sulfide are separated from water in which carbon dioxide and hydrogen sulfide extracted from the decompression tank 11 are dissolved, and oxygen-containing gas supply means is supplied to the separated carbon dioxide and hydrogen sulfide. Although the example using the diffusion tower 12 and the blower 13 as described above in order to mix the oxygen-containing gas supplied from is described, it is not necessarily limited to this. For example, the atmospheric pressure is released through the suction hole of a vaporization tower (gas-liquid separation means: not shown) having suction holes for carbon dioxide and hydrogen sulfide in water in which carbon dioxide and hydrogen sulfide extracted from the decompression tank 11 are dissolved. In this configuration, carbon dioxide and hydrogen sulfide are vaporized into the vaporization tower, and the vaporized carbon dioxide and hydrogen sulfide and the oxygen-containing gas supplied from the oxygen-containing gas supply means are mixed in the vaporization tower. I do not care. Further, the oxygen-containing gas may be directly supplied to the biological desulfurization tower 16 instead of supplying the oxygen-containing gas before the carbon dioxide and hydrogen sulfide are supplied to the biological desulfurization tower 16.

  In the present embodiment, the decompression tank 11 is provided in order to increase the methane recovery rate. For example, without the decompression tank 11, high-pressure water in which carbon dioxide and hydrogen sulfide are dissolved is extracted from the absorption tower 4. Even if carbon dioxide and hydrogen sulfide are separated from water in which carbon dioxide and hydrogen sulfide are dissolved in a vaporization tower (gas-liquid separation means) by releasing atmospheric pressure or the like, it is within the technical scope of the present invention. That is, at least the high-pressure water in which carbon dioxide and hydrogen sulfide extracted from the absorption tower 4 are dissolved is depressurized, and carbon dioxide and hydrogen sulfide are removed from the water in which carbon dioxide and hydrogen sulfide extracted from the absorption tower 4 are dissolved. It only needs to be a separating means having a function of separating.

  Further, in the present embodiment, an example in which Thiobacillus bacteria are used as the sulfur-oxidizing bacteria attached to the filler layer 15 has been described, but the present invention is not necessarily limited thereto.

It is explanatory drawing which illustrates typically the whole structure of the desulfurization apparatus of the digestion gas of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mist separator 2 Hydrogen sulfide concentration meter 3a, 3b Gas compressor 4 Absorption tower 5 Dehumidifier 6 Water supply tank 7 Water supply pump 8 Water circulation pump 9 Heat exchanger 10 Chiller 11 Depressurization tank 12 Stripping tower 13 Blower 14 Air 15 Filling Material layer 16 Biodesulfurization tower

Claims (8)

The digestion gas generated by subjecting the organic waste to methane fermentation is compressed by a compressor and pressurized, the digested gas pressurized is supplied to an absorption tower, and the digestion gas and water whose pressure is increased in the absorption tower And the carbon dioxide and hydrogen sulfide contained in the pressurized digestion gas are dissolved in high pressure water to separate the carbon dioxide and hydrogen sulfide from the pressurized digestion gas, A purification step;
The high-pressure water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved is decompressed, and the carbon dioxide and hydrogen sulfide are extracted from the water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved. Separating the
The separated carbon dioxide, hydrogen sulfide, and oxygen-containing gas are supplied to a biological desulfurization tower having a filler layer to which microorganisms that decompose hydrogen sulfide are attached, and hydrogen sulfide in the mixed gas is utilized using the action of the microorganisms. Disassembling, and
A method for desulfurizing digestion gas, comprising:   The high-pressure water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved is supplied to the biological desulfurization tower, and the carbon dioxide and hydrogen sulfide bubbles generated from the high-pressure water are contained in the biological desulfurization tower. 2. The digestion gas desulfurization method according to claim 1, further comprising a step of cleaning the filler layer.   The digestion gas desulfurization method according to claim 1, further comprising a step of heating the biological desulfurization tower using heat generated from the compressor.   In order to keep the concentration of hydrogen sulfide in the mixed gas supplied to the biological desulfurization tower at a predetermined value, the concentration of hydrogen sulfide in the digestion gas is measured, and according to the measured concentration of hydrogen sulfide, the oxygen The method for desulfurization of digestion gas according to any one of claims 1 to 3, further comprising a step of controlling the amount of the oxygen-containing gas supplied from the containing gas supply means.   The compressor that compresses and pressurizes digestion gas generated by methane fermentation of organic waste, and the digestion gas and water that have been pressurized by the compressor are received and brought into contact with each other in a high-pressure state, thereby increasing the pressure. The carbon dioxide and hydrogen sulfide contained in the digestion gas are dissolved in high-pressure water to separate the carbon dioxide and hydrogen sulfide from the pressurized digestion gas, and an absorption tower for purifying methane, and an extraction from the absorption tower Separating means for depressurizing the high-pressure water in which the carbon dioxide and hydrogen sulfide dissolved are separated to separate the carbon dioxide and hydrogen sulfide extracted from the water in which the carbon dioxide and hydrogen sulfide are extracted from the absorption tower; A biological desulfurization tower having a filler layer that receives the separated carbon dioxide, hydrogen sulfide, and oxygen-containing gas and has microorganisms that decompose the hydrogen sulfide attached thereto. Desulfurizer digestion gas, characterized in that.   In order to clean the filler layer in the biological desulfurization tower with bubbles of the carbon dioxide and hydrogen sulfide in the high-pressure water in which the carbon dioxide and hydrogen sulfide extracted from the absorption tower are dissolved, 6. The digestion gas desulfurization apparatus according to claim 5, further comprising high-pressure water supply means for supplying the biological desulfurization tower.   The recovery means for recovering the heat generated from the compressor, and the heat retaining means for warming the biological desulfurization tower using the heat recovered by the recovery means. Desulfurization equipment for digestion gas as described.   In order to keep the hydrogen sulfide concentration in the mixed gas supplied to the biological desulfurization tower at a predetermined value, the hydrogen sulfide concentration meter for measuring the concentration of hydrogen sulfide in the digestion gas and the hydrogen sulfide concentration meter were used. The digestion according to any one of claims 5 to 7, further comprising control means for controlling an amount of the oxygen-containing gas supplied from the oxygen-containing gas supply means according to a concentration of hydrogen sulfide. Gas desulfurization equipment.

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