CS221457B1 - A method of removing sultan from biogas - Google Patents

Abstract

The purpose of the method for removing sultanate from biogas is to increase the efficiency and regenerability of the adsorption material. According to the invention, the biogas is subjected to the action of a washing solution of chelated iron salts at a temperature of 10 to 99 °C and a pressure of 1 kPa to 3.5 MPa, while the pH of the washing solution is maintained in the range of 7 to 9 by the addition of buffer compounds.

Description

The invention relates to a process for removing sultan from biogas.

Biological processes for the treatment of various types of waste water produce biogas. One of the gaseous toxic components contained in the gas is sulfane. Its presence in biogas causes many difficulties in its use or its disposal. In many cases it is therefore necessary to remove sulfane from biogas.

However, the choice of method for the removal of sulfane from biogas is limited by both high carbon dioxide and water vapor content.

So far, the adsorption method using solid iron oxide materials to capture the sulfane has been used in practice to remove sulfane from biogas. However, the devices are very bulky, inefficient and the regenerability of adsorbent material is difficult and costly. It is also difficult to control and operate the equipment. The equipment occupies a large building space and is capital intensive.

According to the present invention, a method for removing sulfone from biogas is provided by treating the biogas with a scrubbing solution of chelated iron salts at a temperature of 10 to 99 ° C and a pressure of 1 kPa to 3.5 MPa, the pH of the scrubbing solution. is maintained between 7 and 9 by the addition of buffering compounds.

The desulphurization process involves the absorption of hydrogen sulfide in an alkaline solution to form hydrosulfide anions, and in the second phase the hydrogen sulfide anions are reacted with a ferric salt complexed with, for example, ethylenediaminotetraacetic acid tetrasodium EDTA according to the formula:

(Fe ³⁺ EDTA ^4_ ) "+ HS" + H 2 O = 2 (Fe ²⁺ EDTA ^4_ ) ^{2 -} + S + H ₃ O ⁺ .

This reaction takes place almost immediately upon contact of the sulfane-containing gas with the scrubbing solution. Conversion of the reduced form of the scrubbing solution (Fe ²⁺ EDTA ^{4_J 2_)} back to the active oxidized form (Fe ³⁺ EDTA ^4_ is carried out by oxidation with air oxygen according to the formula:

(Fe ²⁺ EDTA ⁴ -) ² - + 4H 3 O + +02 = 4 Fe ³⁺ EDTA ^{4 -} ) + 6 H ² O.

In order to guarantee the correct functioning of the scrubbing solution, it is necessary to maintain its pH in the range of approximately 7 to 9 by adding buffering compounds.

The advantages of the process according to the invention are that the desulphurisation of biogas is less expensive, the device is cheap, easier to operate and the whole desulphurisation process is very efficient. Excluded sulfur can be used in a number of technological processes.

The process according to the invention is further described in the following examples.

Example 1

Biogas containing 5 g of sulfane per m _n ³ was desulfurized with a solution of chelated iron salts to a final content of 50 mg of sulfane in m _n ³ . The reduced form of the wash solution was oxidized back to the active oxidized form by air. The sulfane was scrubbed at 20 ° C. The desulphurized biogas was further combusted.

Example 1 a d 2

Biogas containing 6 g of sulfane in one m _n ³ was desulfurized with a solution of chelated iron salts to a final content of 50 mg of sulfane in m _n ³ . The sulfane was scrubbed at 50 ° C. The desulphurized biogas was further combusted.

Claims (1)

Process for removing sulfane from biogas, characterized in that the biogas is subjected to a scrubbing solution of chelated iron salts at a temperature of from 10 to 99 ° C and to a pressure of 1 kPa to 3.5 MPa, wherein the pH of the scrubbing solution is maintained in range 7 to 9.