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成果報告書詳細
管理番号20190000000348
タイトル*平成30年度中間年報 地熱発電技術研究開発/地熱エネルギーの高度利用化に係る技術開発/酸性熱水利用のための化学処理システム開発
公開日2019/5/22
報告書年度2018 - 2018
委託先名西日本技術開発株式会社 国立大学法人九州大学 国立大学法人富山大学
プロジェクト番号P13009
部署名新エネルギー部
和文要約
英文要約Title: Research and development of geothermal power generation technology/ Development of technology for advanced use of geothermal energy/ Development of chemical processing systems in order to properly utilize acid brine
1. Content and outcome of research and development
(1) Technology development of chemical processing systems for acid brine
1) Evaluation and selection of the type of chemical injection and the materials used for the injection pipe
In order to examine the conditions to prevent acid brine corrosion of the pipes in a geothermal power plant, a corrosion test of a test piece of pipe was conducted by adding alkali and corrosion inhibitor to the acid brine.
Toyama University, observed the thickness of the test piece of pipe at the nanoscale level by using a Phase Shift Interferometer, which allows for a very short term evaluation. West JEC, conducted preliminary small scale corrosion tests by using an autoclave and flow examination at Takigami and Hatchobaru geothermal power plants, and compared the weight of the test pieces. As a result of corrosion tests, some chemicals were selected, which are expected to be effective for corrosion inhibition.
After these preliminary small scale tests, Kyushu University evaluated corrosion products of the test pieces by using SEM and LA-ICP-MS. This made it clear that scale deposited on the test piece at the same time as it was corroded, under neutralization of acid brine.

2) Study of scale component prediction deposited from acid brine and measures to prevent
In order to utilize acid brine, neutralization treatment is generally used as a countermeasure, but there is a problem that scales (such as silica) occur as a result. At Toyama University, using Hatchobaru geothermal power plant as a model case, the pH change and precipitated scale were calculated.
Kyushu University studied the change of brine status (silicic acid concentration, iron and aluminum concentration, particle size, turbidity, etc.) by using Absorption Spectrophotometry and Dynamic Light Scattering both when acid brine is neutralized and when acid brine and neutral brine are mixed. Consequently the turbidity increased as the pH of the mixed brine increased. The produced component of turbidity indicates the possibility of a change in the status of the iron ion.

(2) Technology development of corrosion prevention by utilizing coating materials
The applicability of technology for corrosion prevention by coating the surface of metal with silica scale or corrosion resistant materials is examined. Since the density of silica scale is different depending on the pH of brine at the deposition, temperature condition, and so on, West JEC prepared scale coatings which were produced by immersing test pieces in brines after pH modification on different days at Hatchobaru and Otake geothermal power plants.

(3) System design for acid brine utilization
The general neutralization system for acid brine is selected through the study of existing reports and cases.
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