TY - JOUR
T1 - Recovery of silica from saline geothermal brine at the Yamagawa Power Plant for inhibition of scale formation by batch- and circulation-tests using cationic flocculant and quicklime
AU - Ueda, Akira
AU - Ozawa, Akiko
AU - Unami, Shigeko
AU - Kusakabe, Minoru
AU - Hirayama, Noritaka
AU - Mogi, Katsumi
AU - Ikeda, Makoto
AU - Yokoyama, Takushi
AU - Yonezu, Kotaro
N1 - Funding Information:
We would like to express our gratitude to the members of the Geothermal Department and Yamagawa Power Station of Kyushu Electric Power Co. Inc. for their kind cooperation during our fieldwork. The authors are also grateful to the staff and students at the University of Toyama, Kyushu University, and the Mitsubishi Materials Techno Corp. for their helpful assistance and advice. The authors would also like to thank Enago (www.enago.jp) for their English language review. The authors would like to express our deepest gratitude to the editor and the anonymous reviewers for their generous, critical, and thoughtful comments and advice, which greatly helped us to improve the manuscript. This research was conducted as part of the New Energy and Industrial Technology Development Organization (NEDO) projects: Research and Development of Geothermal Power Generation Technology, Innovative Technology Development for Promotion of Introduction of Geothermal Power Plant, Development of a silica-scale inhibition method by a seed-circulation system.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2022/2
Y1 - 2022/2
N2 - To suppress silica scale deposition from supersaturated silica, two types of field tests, i.e., batch- and circulation-tests were conducted at the Yamagawa Power Plant by adding cationic flocculant and quicklime. In the flow test, an improved seed circulation system was used and the flow rate of brine to be treated was about 1.2 tons/hour. The silicic acid concentration in the brine after steam–brine separation under atmospheric pressure was 630 mg/L. In the batch test, the reagent was mixed with the brine after a delay of zero minutes (no retention time; NRT) or 15–60 min (retention time for 15–60 min; 15 RT to 60 RT) at 90 °C. When a cationic flocculant (DADMAC–No.6) was added at concentrations ranging from 10 to 50 mg/L, the silicic acid concentration decreased to 300 mg/L with increasing retention time, regardless of the reagent concentration. In contrast, in the case of CaO addition, silica recovery rates increased with the amount of CaO added. The silicic acid concentration decreased to approximately 50 mg/L at NRT when 1 g/L CaO was added. In the flow test, DADMAC–No. 6 or CaO was added continuously under various conditions. The silicic acid concentration in the treated brine was reduced to approximately 400 mg/L when DADMAC–No. 6 was used. The turbidity of the treated brine was more than 10 NTU. It needs to be reduced to less than 1 NTU for underground reinjection. In contrast, the silicic acid concentration was approximately 100 mg/L when CaO was used, and the turbidity was approximately 0 NTU. These results indicate that addition of CaO is the best option for silica recovery from geothermal brine at the Yamagawa Power Plant. A practical-scale brine treatment plant has a treatment flow rate of 150 t/h. The estimated treatment cost at this time is 0.86–1.0 USD/ton of brine when DADMAC–No. 6 was used and 0.83–1.48 USD when CaO was used.
AB - To suppress silica scale deposition from supersaturated silica, two types of field tests, i.e., batch- and circulation-tests were conducted at the Yamagawa Power Plant by adding cationic flocculant and quicklime. In the flow test, an improved seed circulation system was used and the flow rate of brine to be treated was about 1.2 tons/hour. The silicic acid concentration in the brine after steam–brine separation under atmospheric pressure was 630 mg/L. In the batch test, the reagent was mixed with the brine after a delay of zero minutes (no retention time; NRT) or 15–60 min (retention time for 15–60 min; 15 RT to 60 RT) at 90 °C. When a cationic flocculant (DADMAC–No.6) was added at concentrations ranging from 10 to 50 mg/L, the silicic acid concentration decreased to 300 mg/L with increasing retention time, regardless of the reagent concentration. In contrast, in the case of CaO addition, silica recovery rates increased with the amount of CaO added. The silicic acid concentration decreased to approximately 50 mg/L at NRT when 1 g/L CaO was added. In the flow test, DADMAC–No. 6 or CaO was added continuously under various conditions. The silicic acid concentration in the treated brine was reduced to approximately 400 mg/L when DADMAC–No. 6 was used. The turbidity of the treated brine was more than 10 NTU. It needs to be reduced to less than 1 NTU for underground reinjection. In contrast, the silicic acid concentration was approximately 100 mg/L when CaO was used, and the turbidity was approximately 0 NTU. These results indicate that addition of CaO is the best option for silica recovery from geothermal brine at the Yamagawa Power Plant. A practical-scale brine treatment plant has a treatment flow rate of 150 t/h. The estimated treatment cost at this time is 0.86–1.0 USD/ton of brine when DADMAC–No. 6 was used and 0.83–1.48 USD when CaO was used.
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U2 - 10.1016/j.geothermics.2021.102312
DO - 10.1016/j.geothermics.2021.102312
M3 - Article
AN - SCOPUS:85120819101
VL - 99
JO - Geothermics
JF - Geothermics
SN - 0375-6505
M1 - 102312
ER -
