成果報告書詳細
管理番号20160000000641
タイトル*平成27年度中間年報 地熱発電技術研究開発 地熱発電の導入拡大に資する革新的技術開発 電気分解を応用した地熱発電用スケール除去装置の研究開発
公開日2016/12/20
報告書年度2015 - 2015
委託先名イノベーティブ・デザイン&テクノロジー株式会社 国立大学法人静岡大学
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 Innovative research and
development for further utilization of geothermal power generation Research and development of
electrolysis scale remover for geothermal power plant FY2015 Annual Report

1.Basic survey on chemical constituents and scales in hot springs
 Hot spring waters were collected from several hot springs in Izu district and their chemical
constituents and scale composition were analyzed by ICP-AES. A hearing survey was made on scale
prevention measures and how often such measures to be taken to prevent scale built-up. In Izu
district, calcium carbonate scales are found common and dominant. However, its scale formation
rate varies from one place to another.
2.Development of an electrolysis scale preventer without ion-exchange membranes adjustable to the
composition of the spring water
 In order to investigate the mechanism of scale formation and dissolution, a series of experiments
were conducted in the laboratory in Shizuoka University using mini-channels. It has been confirmed
that the pH value and temperature of the hardened water are the two major factors associated with
CaCO3 scale formation.
A prototype electrolysis scale preventer without ion-exchange membranes was operated at several
hot spring sites so as to evaluate its performance. Field experiments carried out at the site in
Izunokuni city revealed that the electrolysis of this type is capable of reducing the scale built-up by
50% after a continuous operation of 6 months. Thus, the electrolysis without ion-exchange
membranes, which can run stably without any malfunctioning, is quite effective for the cases in
which both temperature and scale growth rate are moderate. The operation of the electrolysis without
ion-exchange membranes, however, failed for the cases in which the scale growth rate is so high that
the scale chokes tubes. A scaling-up of the electrolysis may ease such constraints associated with
choking tubes.
3.Development of an electrolysis scale preventer with ion-exchange membranes
 CaCO3 easily dissolves in an acid water solution. Thus, cleansing using an acid water solution
produced on the anode side is quite effective to remove possible nuclei of calcium carbonate scales.
Acid cleansing inevitably requires a temporary shut-down of the power generation loop. Thus, acid
injection into the spring water flowing in the tube has been proposed for an alternative way to the
acid cleansing. This injection system to inject the acid solution produced on the anode side of the
electrolysis with membranes was installed upstream of the heat exchanger. The field experiment
conducted using the two distinctive loops, with and without the injection system, respectively,
reveals that the injection system is quite effective to prevent scale formation. Optimal conditions for
pH value and ion concentration in the injection system will be determined by actually running the
system in the hot spring sites.
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