JPH11344200A - Reserving method for digestion gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a gas holder compact and to reduce the cost for an equipment of reservoir facility by using the gas holder filled with an adsorbing material for reserving the digestion gas or methane separated and recovered from the digestion gas. SOLUTION: The digestion gas is passed through an adsorption tower filled with an adsorbing material for desulfurization to adsorb and remove hydrogen sulfide. Then the gas is passed through an adsorption tower filled with carbon dioxide adsorbing material. Then the obtained methane is made to be adsorbed by an adsorbing material filled in a reservoir tank to be reserved. On this occasion, one or more than one kind of methane adsorbing materials can be used. When the activated carbon, zeolite or silica gel is used as the methane adsorbing material, a specific surface area is preferably as large as possible, and should be at least about 1,000 m<2> /g. Further a pore diameter is usually about 4-12 Å, and more preferably about 8-12 Å.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to digestion generated during biological treatment in a sewage treatment plant, a beer manufacturing plant, a waste treatment plant in a livestock and poultry (cattle, pig, chicken, etc.) breeding plant. More particularly, the present invention relates to a method for efficiently collecting / storing methane gas in digestive gas and effectively using the obtained methane as fuel.

[0002]

2. Description of the Related Art Conventionally, in a treatment facility for performing the above-mentioned biological treatment on a large scale (hereinafter sometimes referred to as a "large-scale treatment facility"), generated gas is stored in a gas holder under normal pressure or under pressure. It is used as a power generation or heating raw material as needed. However, in the conventional storage method, since the storage density is low,
If a large-scale gas holder is required and sufficient installation space cannot be obtained, a part of the generated gas is burned and diffused as it is. Further, in a small-scale treatment facility, most of the generated gas is burned and emitted without being used effectively.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a technique for effectively utilizing the entire amount of digestive gas generated during a biological treatment regardless of the size of a treatment facility. And

[0004]

Means for Solving the Problems The inventors of the present invention have studied repeatedly while paying attention to the current state of the technology as described above. As a result, when an adsorbent is used, the digestion gas can be stored efficiently. It has been found that almost all the useful components in the digestive gas can be used regardless of the size of the biological treatment equipment. That is, the present invention provides the following digestion gas storage method: A method for storing a digestive gas, wherein the digestive gas generated during biological treatment is adsorbed and stored as it is or after being separated into individual gas components. 2. Item 2. The method according to Item 1, wherein the gas to be stored by adsorption is methane, carbon dioxide and hydrogen sulfide. 3. The method according to claim 1, wherein the gas to be absorbed and stored is methane. 4. Item 2. The method according to Item 1, wherein the adsorbent is at least one of activated carbon, zeolite, silica gel and an organic complex metal. 5. Item 1 in which the components in the digested gas are separated in the order of hydrogen sulfide, carbon dioxide and methane, and methane is absorbed and stored.
The method described in.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, (A) hydrogen sulfide, carbon dioxide and methane in a digested gas are separated in this order, and then methane is adsorbed and stored in a tank filled with an adsorbent, or (B) After simultaneously removing hydrogen sulfide and carbon dioxide in digested gas, methane is adsorbed and stored in a tank filled with an adsorbent, or (C) methane, carbon dioxide and sulfide, which are main components of digested gas, Hydrogen is adsorbed and stored in a mixed state in a tank filled with an adsorbent. In the present invention, the method (A) of separating the main components in the digested gas from each other and adsorbing and storing high-purity methane is more preferable. Hereinafter, the method (A) will be mainly described in detail.

In the method (A), first, the digestion gas is passed through an adsorption tower filled with an adsorbent for desulfurization to adsorb and remove hydrogen sulfide. Examples of the adsorbent include activated carbon, zeolite, and metal oxides (copper oxide, zinc oxide, etc.) conventionally used as desulfurizing agents. The temperature and pressure at the time of adsorption may be the digestion gas generation state as it is and are not particularly limited, but the temperature is usually from normal temperature to about 100 ° C (more preferably, from normal temperature to about 60 ° C), and the pressure is from normal pressure to 1MPa
It is about. The desulfurization operation may be performed in a batch mode,
Alternatively, the continuous desulfurization operation and the desulfurization agent regeneration operation may be alternately performed using two or more columns to perform a continuous regeneration treatment. The regeneration of the desulfurization adsorbent is performed by blowing heated steam into the adsorption tower to separate hydrogen sulfide.

The digestion gas from which hydrogen sulfide has been adsorbed and removed is
Then, it is passed through an adsorption tower filled with a carbon dioxide adsorbent. Examples of the adsorbent include activated carbon, zeolite, and organic metal complexes (copper fumarate, copper cyclohexanedicarboxylate, copper stilbene dicarboxylate, copper terephthalate, terphenyldicarboxylic acid, biphenyl) conventionally used as carbon dioxide adsorbents. Copper dicarboxylate, copper transdicarboxylate, etc.). The temperature and pressure during adsorption are not particularly limited, but the temperature is about room temperature to about 100 ° C. (more preferably, room temperature or near room temperature), and the pressure is about room pressure to about 1 MPa (more preferably, room temperature or about room temperature). ). The operation of adsorbing carbon dioxide may be performed by a batch method or by a PSA method using two or more columns. According to the PSA method, high-purity methane with a purity of 99% or more can be obtained. The regeneration of the carbon dioxide adsorbent can be performed in the same manner as the regeneration of the desulfurization adsorbent.

[0008] The methane thus obtained is adsorbed on an adsorbent filled in a storage tank and stored. The temperature and pressure during adsorption are not particularly limited, but the temperature is usually from room temperature to normal temperature.
The temperature is about 100 ° C. (more preferably, at or near room temperature), and the pressure is from about normal pressure to about 3.4 MPa. As the methane adsorbent, activated carbon, zeolite, silica gel, organic metal complexes (copper fumarate, copper cyclohexanedicarboxylate, copper stilbene dicarboxylate, copper terephthalate, terphenyldicarboxylic acid, copper biphenyldicarboxylate, copper transdicarboxylate, etc.) And the like. These methane adsorbents can be used alone or in combination of two or more. When activated carbon, zeolite or silica gel is used as the methane adsorbent, the specific surface area is preferably as large as possible and practically required to be at least 1000 m ² / g or more. Also, its pore size is usually 4 ~ 12mm
Degree, more preferably about 8 to 12 degrees.

The temperature and pressure at the time of methane adsorption may be the same as the temperature and pressure at the time of obtaining methane, and are not particularly limited. The temperature is usually about normal temperature to 100 ° C. (more preferably about normal temperature to 60 ° C.). The pressure is equal to or higher than normal pressure (more preferably, normal pressure to about 3.4 MPa). When it is necessary to increase the storage pressure, methane is pressurized by a compressor, then adsorbed and stored.

[0010] In the method (B), an aqueous solution of sodium hydroxide (preferably about 20 to 40%) is used as an absorption liquid for digestion gas.
Hydrogen sulfide and carbon dioxide in the digested gas are simultaneously separated and removed by bubbling inside, and methane (purity 93% or more) is adsorbed and stored in a tank filled with adsorbent in the same manner as in method (A). I do.

[0011]

According to the present invention, a gas holder filled with an adsorbent is used to store digestive gas or methane separated and recovered from digestive gas, thereby reducing the size of the gas holder and reducing the equipment cost of a storage facility. Can be reduced.

Therefore, according to the present invention, it is possible to effectively use the digestion gas generated during the biological treatment regardless of the size of the treatment equipment.

[0013]

EXAMPLES Examples are shown below to further clarify the features of the present invention. Example 1 4000 Nm ³ of digested gas generated in a sewage treatment plant was passed through a zeolite packed tower to adsorb and remove hydrogen sulfide, and then passed through an activated carbon packed tower to adsorb and remove carbon dioxide.

The thus obtained 99% methane (2600Nm ³⁾
124 m ³ filled with 78 tons of powdered activated carbon (specific surface area 1400 m ² / g)
At normal temperature and normal pressure. Comparative Example 1 In order to store 4000 Nm ³ of the digested gas as in Example 1 at normal temperature and normal pressure according to the conventional method, a gas holder of 4000 m ³ was required. 99% methane 2600 nm ³ obtained in the same manner as in Example 1 using the same powdered activated carbon as in Example 1, was adsorbed at a pressure of normal temperature and 1.0 MPa, to fill 26 tons of powdered activated carbon 37
Storage was possible with an m ³ gas holder. Comparative Example 2 In order to adsorb and store 4000 Nm ³ of the same digestive gas as in Example 1 at normal temperature and a pressure of 1.0 MPa, a 400 m ³ gas holder was required. Example 3 99% methane (2600 Nm ³⁾ obtained in the same manner as in Example 1 was adsorbed at room temperature and a pressure of 3.4 MPa using the same powdered activated carbon as in Example 1, and filled with 18 tons of powdered activated carbon. twenty three
Storage was possible with an m ³ gas holder. Comparative Example 3 In order to adsorb and store 4000 Nm ³ of the same digestive gas as in Example 1 at normal temperature and a pressure of 3.4 MPa, a gas holder of 114 m ³ was required.

Claims (5)

[Claims] 1. A method for storing a digestive gas, wherein a digestive gas generated during a biological treatment is adsorbed and stored as it is or after being separated into respective gas components. 2. The method according to claim 1, wherein the gas to be adsorbed and stored is methane, carbon dioxide and hydrogen sulfide. 3. The method according to claim 1, wherein the gas to be adsorbed and stored is methane. 4. The method according to claim 1, wherein the adsorbent is at least one of activated carbon, zeolite, silica gel and an organic complex metal.
The method described in. 5. The method according to claim 1, wherein the components in the digested gas are separated in the order of hydrogen sulfide, carbon dioxide and methane, and the methane is adsorbed and stored.