KR101086971B1 - Method and Apparatus of Refining Bio-Methane Gas - Google Patents

Abstract

More specifically, the present invention relates to a biomethane purification method for purifying biomethane from biogas generated by anaerobic digestion of organic waste such as sewage sludge, livestock waste, landfill waste, food waste, etc. The purification method includes a tower 11 constituting a body, a water supply pipe 12a connected to an upper end of the tower 11 to supply water, and a water discharge pipe 12b connected to a lower end of the tower 11 to discharge water; ), A gas supply pipe 13a connected to the lower end of the tower 11 to supply unrefined biogas, and a gas discharge pipe 13b connected to an upper end of the tower 11 to discharge purified biogas; , Using an absorption tower including a porous structure 14 installed in multiple stages on a passage of the tower 11, supplying water as an absorption liquid through the water supply pipe, and supplying a gas supply pipe. Through when methane and carbon dioxide is supplied to the main components of biogas, is the absorption of carbon dioxide in the water are purified by the main component methane.

Biogas, Purification, Methane, Carbon Dioxide, Absorption Tower, Absorbent

Description

Method for Purifying Biomethane {Method and Apparatus of Refining Bio-Methane Gas}

The present invention relates to a biomethane purification method, and more particularly, to a biomethane purification method for purifying biomethane from biogas generated by anaerobic digestion of organic waste such as sewage sludge, livestock waste, landfill waste, and food waste. will be.

In general, in landfills or anaerobic digesters, organic substances contained in waste are decomposed, resulting in odorous components including methane gas, carbon dioxide and traces of harmful substances.

Although methane gas can be used as a fuel resource through proper separation and purification process, it can diffuse into the atmosphere, pollute the atmosphere, and cause explosion or fire during volatilization to the atmosphere. It acts as an environmentally harmful substance, causing death of plants.

In addition, recently, methane and carbon dioxide have been an important environmental issue due to the effects of global warming, and these gases cause global warming, causing environmental changes and structural changes in ecosystems.

On the other hand, biogas can be classified into anaerobic digestion reactor gas and landfill gas (LFG) discharged from sewage treatment plant, food waste treatment plant, etc., and there is a big difference in gas composition. It is composed of methane (about 50-60v%), carbon dioxide (39-49v%), and other odorous gases such as sulfur and nitrogen compounds.

Removing sulfur compounds and nitrogen compounds from the odor generating gas can produce a mixture of high purity methane and carbon dioxide, but a technology for separating carbon dioxide and methane is required.

Accordingly, an object of the present invention is to solve the problems derived from the above-described prior art, and the present invention provides biomethane from biogas generated by anaerobic digestion of organic waste such as sewage sludge, livestock waste, landfill waste, and food waste. It is an object of the present invention to provide a method for purifying biomethane.

Biomethane purification method according to the present invention in order to achieve the above object is a tower 11 constituting the body, the water supply pipe 12a and the tower 11 is connected to the top of the tower 11 to supply water It is connected to the lower end of the water discharge pipe (12b) connected to the lower end, the gas supply pipe (13a) connected to the lower end of the tower 11 to supply the purified biogas and the top of the tower (11) An absorption tower including a gas discharge pipe 13b for discharging purified biogas and a porous structure 14 installed in multiple stages on a passage of the tower 11 is used, and water absorbed through the water supply pipe. After supplying and supplying a biogas containing methane and carbon dioxide as a main component through a gas supply pipe, carbon dioxide is absorbed into the water and methane is purified as a main component.

At this time, the water has a hydrogen ion concentration (pH) of 6-8, the electrical conductivity of the water at 20 ℃ is 150 to 200μS / ㎝, the temperature of the water supplied to the absorption tower is preferably 10 to 20 ℃.

The present invention as described above provides a biomethane purification method for purifying biomethane from biogas generated by anaerobic digestion of organic waste such as sewage sludge, livestock waste, landfill waste, food waste.

In addition, according to the biomethane purification method of the present invention, biomethane containing 95v% or more of methane can be obtained from a biogas containing 50v% or more of methane and 50v% or less of carbon dioxide.

In addition, according to the biomethane purification method of the present invention, by producing biomethane containing high purity methane from biogas containing methane and carbon dioxide, it is possible to prevent environmental pollution by preventing ocean dumping and landfilling of organic waste. In addition, organic waste can be recycled.

Other features and operations of the present invention in addition to the above objects will become apparent from the embodiments described below with reference to the accompanying drawings.

The detailed description set forth below in connection with the appended drawings is made with the intention of describing preferred embodiments of the invention, and does not represent the only forms in which the invention may be practiced. It should be noted that the same and equivalent functions included in the spirit or scope of the present invention may be achieved by other embodiments.

Certain features disclosed in the drawings are enlarged for ease of description, and the drawings and their components are not necessarily drawn to scale. However, those skilled in the art will readily understand these details.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram illustrating an absorption tower used in the biomethane purification method according to an embodiment of the present invention.

Referring to Figure 1, the absorption tower 10 used in the biomethane purification method of the present invention uses a conventional absorption tower, the structure is a tower 11 constituting the body, and the top of the tower (11) A water supply pipe 12a connected to supply water and a water discharge pipe 12b connected to a lower end of the tower 11 to discharge water, and a biogas that is not purified by being connected to a lower end of the tower 11. A gas discharge pipe 13b connected to an upper end of the gas supply pipe 13a and the tower 11 to discharge purified biogas, and a structure 14 installed on the passage of the tower 11 in multiple stages. do.

At this time, the structure 14 is made of a porous material, such as a plate formed with a plurality of holes in a circular plate body, and in the process of passing water through the hole to increase the contact area of carbon dioxide and the water absorbing water to the maximum in the biogas Allow carbon dioxide to be absorbed by water.

Hereinafter, a biomethane purification method using a biomethane purification device according to an embodiment of the present invention will be described.

First, water is supplied through the water supply pipe 12a on the top of the tower 11 forming the body of the absorption tower 10. In this case, the water is used as an absorbing liquid that absorbs carbon dioxide (CO ₂ ).

Then, the biogas is supplied through the gas supply pipe 13a below the tower 11. The supplied biogas is a biogas produced by anaerobic digestion of organic waste such as sewage sludge, livestock waste, landfill waste, food waste, and generally contains 50v% to 60v% methane and 40v% to 50v% carbon dioxide.

When the biogas is supplied, the biogas moves upward through a passage inside the tower 11, passes through the hole of the structure 14, and comes into contact with water. At this time, water absorbs carbon dioxide as an absorbent liquid.

Since the structure 14 is formed in multiple stages, as the biogas moves toward the top of the tower 11, carbon dioxide is removed to increase the content of methane.

The water absorbing the carbon dioxide moves downward through the structure 14 installed in multiple stages on the passage inside the tower 11 and is discharged to the outside through the water discharge pipe 12b.

In addition, the biogas from which carbon dioxide is removed through absorption of water contains 95 mV or more of methane. The purified biogas is moved to the top of the tower 11 and discharged to the outside through the gas discharge pipe 13b. Although not shown in the drawing, the biogas may be stored in a storage tank or the like.

On the other hand, the water supplied to the absorption liquid for absorbing the carbon dioxide is preferably a hydrogen ion concentration (pH) of 6 to 8. This means that when the hydrogen ion concentration (pH) of the water exceeds 8, the water exhibits an alkaline property, so that the rate of carbon dioxide absorption in the biogas is reduced. When the hydrogen ion concentration (pH) of the water is less than 6, The water has an acidic nature, so that the rate of carbon dioxide absorption in the biogas is lowered, thereby reducing the removal rate of carbon dioxide in the biogas.

In addition, the water has an electrical conductivity of 150 to 200μS / cm at 20 ℃. When the electrical conductivity of water is less than 150μS / cm, the cost of producing water as an absorbent solution is excessively expensive, and the economic efficiency is low.When the conductivity of water exceeds 200μS / cm, it contains pollutants in the water, so that carbon dioxide in the biogas It is because the ratio which can absorb the water becomes small.

In addition, the water should be maintained at a temperature of 10 to 20 ℃. This is associated with an increase in the solubility of carbon dioxide in water as the absorbent liquid at lower temperatures. If the temperature of the water exceeds 20 ° C, the solubility of carbon dioxide in water decreases, and the water cannot absorb carbon dioxide sufficiently. In addition, when the temperature of the water is less than 10 ℃ requires an additional refrigeration equipment in order to lower the temperature of the water to increase the investment cost and operating cost of the biomethane manufacturing equipment is disadvantageous in terms of economics.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the examples.

(Example 1)

A biogas containing 50v% methane and 50v% carbon dioxide is fed to the bottom of the absorption tower with the structured packing, and the temperature of the water sprayed from the top of the absorption tower is 20 ° C, and the hydrogen ion concentration (pH) is 7. The biogas was purified under the condition of 150 µS / cm per unit centimeter.

(Example 2)

 The biogas containing 50v% methane and 50v% carbon dioxide is fed to the lower part of the absorption tower with the structured packing, and the temperature of water sprayed from the upper part of the absorption tower is 10 ℃ and the hydrogen ion concentration (pH) is 7. The biogas was purified under the condition of 150 µS / cm per unit centimeter.

(Example 3)

 The biogas containing 50v% methane and 50v% carbon dioxide is fed to the lower part of the absorption tower with the structured packing, and the temperature of water sprayed from the upper part of the absorption tower is 10 ℃ and the hydrogen ion concentration (pH) is 7. The biogas was purified under the condition of 200 μS / cm per unit centimeter.

(Comparative Example 1)

 The biogas containing 50v% methane and 50v% carbon dioxide is supplied to the lower part of the absorption tower with the structured packing, and the temperature of the water sprayed from the upper part of the absorption tower is 30 ℃ and the hydrogen ion concentration (pH) is 7. The biogas was purified under the condition of 150 µS / cm per unit centimeter.

(Comparative Example 2)

  The biogas containing 50v% methane and 50v% carbon dioxide is fed to the lower part of the absorption tower with the structured packing, and the temperature of water sprayed from the upper part of the absorption tower is 10 ℃ and the hydrogen ion concentration (pH) is 7. Biogas was purified under the condition of 250 μS / cm per unit centimeter.

(Comparative Example 3)

 A biogas containing 50v% methane and 50v% carbon dioxide is fed to the bottom of the absorption tower with the structured packing and the water sprayed from the top of the absorption tower has a temperature of 30 ° C and a hydrogen ion concentration (pH) of 9; Biogas was purified under the condition of 300 μS / cm per unit centimeter.

Table 1 below shows the results of analyzing the contents of methane and carbon dioxide when the biogas was purified under the conditions of Examples 1 to 3 and Comparative Examples 1 to 3.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Methane content
(v%) 96v% 98v% 97v% 92v% 91v% 90v% carbon dioxide
Content (v%) 4v% 2v% 3v% 8v% 9v% 10v%

As shown in Table 1, when the biogas is purified under the conditions of Examples 1 to 3, it can be seen that the biomethane can be obtained by purifying the biogas to 95 mV or more.

1 is a conceptual diagram illustrating an absorption tower used in the biomethane purification method according to an embodiment of the present invention.

Claims (2)

A tower 11 constituting the body, a water supply pipe 12a connected to an upper end of the tower 11 to supply water, and a water discharge pipe 12b connected to a lower end of the tower 11 to discharge water; A gas supply pipe 13a connected to a lower end of the tower 11 to supply unrefined biogas and a gas discharge pipe 13b connected to an upper end of the tower 11 to discharge purified biogas, and the tower Using an absorption tower including a porous structure 14 installed in multiple stages on the passage of (11), When water, which is an absorption liquid, is supplied through the water supply pipe, and a biogas including methane and carbon dioxide is supplied through a gas supply pipe, carbon dioxide is absorbed into the water to purify the biomethane containing methane, The water has a hydrogen ion concentration (pH) of 6-8, The electrical conductivity of water at 20 ° C. is 150 to 200 μS / cm, The temperature of the water supplied to the absorption tower is a biomethane purification method, characterized in that 10 to 20 ℃. delete

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