Feasibility Design of Binary ORC Using Wet Cooling Tower (Existing) of Unit V and VI in Lahendong Geothermal Field, Indonesia

Abstract

Utilization of hot brine from production separator have a great potential to generate electricity as a secondary turbine in Lahendong and the other PT PGE fields. In existing, the separated water from separator will toward directly into reinjection wells with gravity due to had a different elevation about 60 metres. In order to utilize hot brine from production separator, we should modify the existing line with making pipe branch 6’ schedule 40 toward secondary turbine, from main line 16” schedule 40. The pressurised water from upstream (7.83 barg) have a pressure drop 0.13 barg and heat loss 0.019°C along 30 metres of new pipeline. This feasibility study has chosen Pentane as the best selection of binary working fluids due to had power output greater than others and the surface condenser with pressure 1.32 bara is connected to the existing wet cooling tower as the cooling system. The calculation using Scilab and CoolProp as numerical computation, with vaporizer pressure 8.63 bara or 7.70 barg resulting net power 1795.32 kW and SSI value 2.02, while using vaporizer pressure 18.7 bara resulting nett power 626.1 kW with SSI value 0.99.