http://journal.uir.ac.id/index.php/JGEET E-ISSN : 2541-5794 P-ISSN : 2503-216X Journal of Geoscience, Engineering, Environment, and Technology Vol 08 No 02-2 2023 Special Edition Special Issue from β€œThe 1st International Conference on Upstream Energy Technology and Digitalization (ICUPERTAIN) 2022” Nurlatifah & Purwakusumah/ JGEET Vol 08 No 02-2 2023 18 Special Issue from The 1st International Conference on Upstream Energy Technology and Digitalization (ICUPERTAIN) 2022 RESEARCH ARTICLE Possibilities Study of a Non-condensable Gas Exhaust System through the Condensate Injection Pipe at PLTP Wayang Windu Annisa Nurlatifah1, Anton Purwakusumah1,* 1 Wayang Windu Geothermal Power Station, Tromol Pos 1, Margamukti Pangalengan, Bandung, Indonesia * Corresponding author: Anton.Purwakusumah@starenergy.co.id May 20, 2023. Revised : May 31, 2023, Accepted: June 10, 2023, Published: July 31, 2023 DOI: 10.25299/jgeet.2023.8.02-2.13878 Abstract Wayang Windu Geothermal Power Plant, located in Pangalengan, Bandung regency, West Java with an installed capacity of 227 MWe has two units to generate electricity and deliver to the Jawa, Madura, and Bali grid. The steam extracted from the reservoir contains non- condensable gas of about 1-1.2% of total steam extracted, with the gas composition is CO2 92%, H2S 2%, NH3 0.1%, and residual gasses 4.9%. Possibilities study of a non-condensable gas exhaust through the condensate injection pipe was created as the efforts in the environmental conservation aspect for reducing carbon released to the atmosphere and reinjected back into the reservoir. This study was simulated in Wayang Windu Unit 2 by calculating the non-condensable gas flow rate from the gas removal system into the condensate injection pipe near of cooling tower blowdown power station area. The analysis result of this study indicates that the non-condensable gas requires a higher flow rate of condensate to dissolve the entire non-condensable gas, and may cause the slug flow pattern which would endanger the condensate pipeline system also destabilize the non-condensable gas exhaust operation process from the condenser through the gas removal system. To deal with this problem, the possibility of exhausting the non-condensable gas produced by the gas removal system can be alternated by flowing its non-condensable gas into a flash absorber system and converting its non-condensable gas into other eco-friendly products and power plant safe. Keywords: Non-Condensable Gas, Condensate, Gas Removal System, Geothermal, Carbon Capture, Reservoir, Condensate Reinjection, Pipeline, Flash Absorber, Power Plant, Eco-friendly. 1. Introduction Every power plant almost always impacts the environment to a different degree depending on the technology used. Gas emissions from power plants come from non-condensable gases carried by steam from the reservoir. The geothermal fluid that comes out of the well usually still contains gas that cannot be condensed in the condenser so if left unchecked it can cause the pressure in the condenser to rise and decrease turbine efficiency. PLTP Wayang Windu is equipped with a gas exhaust system consisting of a two-stage steam jet ejector and a vacuum pump, so it is called a two-stage hybrid gas exhaust system. The gas that is carried along with the steam from the well that is not condensed in the condenser is sucked in by the GRS and then discharged into the atmosphere through the cooling tower with the help of a fan drive. 1.1 Solubility of NCG in Water Absorption is the process of dissolving the components of the gas phase into the liquid phase. Gas has a small density, if the gas is in contact with a liquid, a number of gas molecules will seep into the liquid with different solubility. The concentration of dissolved gases is highly dependent on the specific temperature and pressure. According to Henry's law, the solubility of a gas in a liquid is directly proportional to the pressure of the gas before it enters the solution. Dalton’s law of partial pressures states that, for a mixture of non-reacting gases, the total of the partial pressure of each gas is equal to the total pressure exerted by the mixture, at constant temperature and volume. The pressure in the transfer medium is the sum of the gas pressure and the water pressure. This applies according to Dalton's law of partial pressure. Make sure that placing and numbering of equations is consistent throughout your manuscript. Eqn. 1, 2, and 3 are written as follow: π‘ƒπ‘‘π‘œπ‘‘π‘Žπ‘™ = π‘ƒπ‘”π‘Žπ‘ π‘’π‘  + 𝑃𝐻2𝑂 (1) π‘ƒπ‘”π‘Žπ‘  = 𝑃𝐢𝑂2 + 𝑃𝐻2𝑆 + 𝑃𝑁𝐻3 (2) 𝑝𝑉 = 𝑛𝑅𝑇 (3) The pressure of the gases on the NCG can be found using Henry's law equation (Eqn. 4). π‘ƒπ‘”π‘Žπ‘  = πΎπ‘”π‘Žπ‘  π‘₯ πΆπ‘”π‘Žπ‘  (4) With: π‘ƒπ‘”π‘Žπ‘  πΎπ‘”π‘Žπ‘  πΆπ‘”π‘Žπ‘  = Partial pressure of the gas (Pa) = Henry’s constant value (L.atm/mole) = Mole fraction of the gas This equation also applies to other gases by including the number of moles from the Henry constant which has been applied based on the partial Henry gas law (Eqn. 5). 𝑆𝑔 = πΎβ„Ž π‘₯ 𝑃𝑔 (5) With: 𝑆𝑔 πΎβ„Ž π‘ƒπ‘”π‘Žπ‘  = Solubility of the gas = Henry’s constant value (L.atm/mole) = Partial pressure of the gas (atm) http://journal.uir.ac.id/index.php/JGEET Nurlatifah & Purwakusumah/ JGEET Vol 08 No 02-2 2023 19 Special Issue from The 1st International Conference on Upstream Energy Technology and Digitalization (ICUPERTAIN) 2022 1.2 Horizontal Flow of a Two-Phase Fluid When two phases flow in a pipe, the different phases can contribute in terms of flow pattern which will cause different flow hydrodynamics, as well as the mechanisms of momentum, heat, and mass transfer around the fluid. The two-phase flow pattern has two flow models: homogeneous and separable. In the homogeneous model, the steam and water are assumed to be completely miscible, so that the water and gas mixture acts like a single-phase fluid with properties averaging depending on the properties of the individual phases. With this assumption, the flow pattern is considered a calculation method for single-phase flow In the separated flow model the flow pattern is assumed to flow together in the pipe separately, each phase distributed in an occupying part of the pipe flow (Saptadji, 2001). Beggs and Brill grouped the two-phase flow patterns in the horizontal plane into 3 groups, namely: segregated flow, intermittent flow, and distributed flow. The segregated flow pattern is divided into three, namely stratified flow, wavy flow, and annular flow (Beggs and Brill, 1973). Intermittent flow patterns are divided into slug flow and plug flow, while the distributed flow pattern is divided into flows bubbles and mist flow. Segregated flow patterns occur when Frm L1 and Frm >L2, and intermittent flow pattern occurs when L1