TITLE Development of CH4 Separation System from Biogas by "Membrane/Absorption Hybrid Method"
(Joint Program to Promote Technological Development with the Private Sectors)
ABSTRACT The aim of this research is to promote the use of biogas (methane 60vol% and carbon dioxide 40vol%). If the use of biogas increases, that of fossil fuel can be decreased.
Our development goal is not only " methane concentration of 98vol% or more and methane collection rate of 98% or more" but also to achieve a inexpensive separation cost.
To achieve the development goal, we use the “Membrane/Absorption Hybrid Method”. We want to put this technology to practical use as early as possible. In the use of the “Membrane/Absorption Hybrid Method” to separate biogas, we are the first in the world.
The development period is two years from fiscal year 2006 to fiscal year 2007.
In fiscal year 2007, We executed the examination that used a mock gas in the laboratory with a substantiation unit that had been produced in 2006 fiscal year. The examination contents are an evaluation of the substantiation unit performance , improvement of the technical problem , the found of the optimum conditions of the operating-condition and control-techniques. Moreover, we constructed the biogas evaluation equipment (the examination temporary housing building , the gas-piping, and power generating machine) . Afterward , we executed the substantiation examination for two months on the biogas production site.
The biogas separation performance in the substantiation examination was the methane concentration of 98vol%, and a methane collection rate of 96-98%.
We evaluated the influences of impurity elements(mainly hydrogen sulfide) contained in the biogas. It is measured by setting up the purifying tower of the hydrogen sulfide before the substantiation unit.
As a results, the lower performance of the membrane penetration performance and biogas separation performance of the carbon dioxide absorption solutions according to the passage of time was not admitted. The practicality of the combination of hydrogen sulfide removal tower where iron oxide had been used and the substantiation unit was able to be confirmed. And also, the durability of the membrane-module on the carbon dioxide absorption solution was adequate.
A practical system that controlled the water supply and the condensation water return of the evaporation moisture was automatically able to be established about the condition control of the carbon dioxide absorption solution.
During a continuous running by biogas, only trouble did not occur in the composition equipment and the regulating system. 
By this technical development, the practicality of methane separation system from biogas by “Membrane/Absorption Hybrid Method”was able to be confirmed and also the operating condition was able to be confirmed. In the future, the improvement of further the energy saving, miniaturization, lowering the cost, safety-system of commercialization-level would be executed upon based on this result of this technical development. And we would forward technical reliability improvement of the "methane separation system from biogas by Membrane/Absorption Hybrid Method"