Application: Biogas, Engine Waste Heat
Power Output: 40 kWe
Thermal Input: 500 kWth
Hot Water Inlet Temperature: 94°C
Hot Water Flow Rate: 12 l/s
In the Czech Republic, ElectraTherm and biogas plant constructor EnviTec Biogas, commissioned an ElectraTherm Power+ Generator at a biogas plant to take advantage of the biogas waste heat to generate additional power and increase energy efficiency on site. The Power+ Generator uses Organic Rankine Cycle (ORC) technology to generate fuel-free, emission-free power.
ElectraTherm’s ORC system was added at an existing biogas power facility with a Jenbacher 412 internal combustion (IC) engine producing 844kWe. The engine is equipped with an exhaust gas heat exchanger, and is configured to have a higher jacket water temperature, which provides a combined jacket water and exhaust heat stream of 95°C. The Power+ Generator is the first heat load on this hot water circuit, and generates up to 40 kWe. After the Power+ Generator has removed heat from the hot water circuit, the anaerobic digester removes heat, followed by several buildings for district heating. Any excess heat not consumed by the Power+, anaerobic digesters, or building heat is removed by the engine cooling radiator.
ElectraTherm’s patented ORC, waste heat recovery technology begins with hot water entering the Power+ Generator at 94°C, where it heats a working fluid into a pressurized vapor. The high pressure vapor expands through ElectraTherm’s patented twin screw power block, spinning an electric generator. After turning the expander, the vapor is condensed back into a liquid through the use of a liquid loop radiator with some heat also being used for nearby district heating.
This biogas plant is the first of its kind to connect the Power+ Generator to the first heat loop, providing it with higher waste heat temperatures to increase power output, while maintaining proper heat input to the anaerobic digesters. The addition of the machine reduces the onsite electricity needed to reject excess heat through radiator fans, increasing plant efficiency by up to 8%. As a result, the Power+ Generator improves site economics by producing electricity and lowering onsite power demands.