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Geothermal scaling mitigation plant of PT Geo Dipa Energi, Indonesia

Geothermal scaling mitigation plant of PT Geo Dipa Energi, Indonesia Thorsteinn Sigmarsson of Mannvit on site at Dieng, Indonesia (source: video screenshot, Mannvit/ Geo Dipa)
Alexander Richter 15 Sep 2022

Presenting a paper at this year's IIGCE in Jakarta, Indonesia, Icelandic engineering firm presents its work on a pilot scaling plant set up for the geothermal operations at Dieng by PT Geo Dipa Energi.

Icelandic engineering firm Mannvit is presenting “New Pilot Plant Unit for Optimization of Geothermal Power Process” about a new mobile pilot plant unit that was designed and built for Geo Dipa Energi (GDE) in Indonesia at the Indonesia International Geothermal Convention & Exhibition, September 14-16, 2022. The purpose of the pilot plant was to test different process cycles and find the most effective method of scale mitigation for GDE geothermal power plants. The pilot plant was designed with great flexibility, with two parallel process lines for testing two process options simultaneously.

The development of geothermal power plant is a large investment.  Thorough planning is most important, here including to understand the geothermal resource, to operate drilling campaigns and flow test the wells, but not the least to interpret test results and from there to determine the most feasible power process. Likewise, when planning for extension of an existing geothermal power plant or even just increasing the efficiency of an operating plant, selecting the most suitable method is important. Not only is this important factor to maximize the power output throughout the plant lifetime but as well may this affect the plant availability factor, either in positive or negative way.

The pilot plant went into operation in 2021, which is intended to test the treatment of the geothermal water in order to reduce silica scaling before the design and construction of an expansion unit of the geothermal power plant.

The role of Mannvit and the Icelandic consultants Kemía and ÍSOR and local consultant CBN, was to provide a complete solution, including; design and engineering, manufacturing, operation and commissioning and training in the operation of the plant.

The operation of the pilot plant has been successful, according to Thorsteinn Sigmarsson, Director of Asian Market and geothermal expert at Mannvit, who has worked extensively in the design and installation of the station, which is located in Dieng.

The operation of Dieng 1, which is already in place, has been significantly affected by scaling and as a result Geo Dipa Energi hired the consulting team from Iceland to assist with a problem before designing the next phase of the power plant. The consultants in the team have tremendous experience in treating scaling. Mannvit’s staff from Iceland and its office in Jakarta, Indonesia worked closely in the entire process along with the other members of the Icelandic consulting team and staff from Geo Dipa Energi.

Pilot plant set up at Dieng, Indonesia (source: Mannvit)

 

The Process

The brine and steam from well being tested is led through intake spool where the intake pressure is controlled and the two-phase flow regulated by a combination of orifice and pressure control valve. For safety of personnel and equipment the flow to the pilot plant is automatically stopped by emergency shut-off valve in case of abnormal operation or failure of power, compressed air, or cooling water supply. The steam is separated from brine in low- and high-pressure separators. The chemicals for mitigation can be accurately dosed into the brine either before separation (two phase) or into separated brine. The brine from the separators is divided into two test lines. One line consists of vaporizer and preheater simulating a brine heated organic Rankine cycle.

The other line is used for simulating high pressure separation. The steam is condensed and used for diluting of fluid handling chemicals and to dilute the brine for injection tests. The separator pressures and levels are automatically controlled and temperatures and flows in the test lines monitored online. The brine flow in the test lines is controlled by orifices and control valve at the outlet. Holdup vessels can be used for increasing the residence time to simulate the proposed actual conditions in the injection lines of full-size plant. The holdup vessels consist of serially connected vertical pipes with narrow residence time and downward flow to avoid separation of suspended solids. Finally, the suitability of brine for injection can be tested in a packed be filled with rock cuttings.

Mannvit’s staff work on the installation in Dieng, Indonesia (source: company)

Source: Company