High temperature organic rankine cycle (HT-ORC) for cogeneration of steam and power

Abstract

Organic Rankine Cycle (ORC) systems are considered as the best available technology for heat to electricity conversion from low temperature heat sources, with continuous developments done to optimize performances by means of new working fluids, improved design and thermodynamic cycles. For electric power production from medium and high temperature heat sources, ORC and Steam Rankine Cycle solutions are competing in terms of electric efficiency, power production, investment, operation and maintenance costs to be selected as the best solution on a case-by-case basis. Commercially available ORC technology is typically limited to a maximum working fluid temperature of about 300°C. Turboden has developed a solution that may operate at temperatures close to 400 °C, improving the ORC technology competiveness in terms of efficiency, especially in Combined Heat and Power schemes with high temperature cogeneration to produce low and medium pressure steam. This High Temperature ORC solution allows ORC technology to be deployed in market segments traditionally belonging to other technologies (e.g. Steam Rankine Cycles, Otto Cycles, Bryton Cycles) to satisfy industrial steam heat users like paper production facilities, MDF plants, organic chemical production, textile, rubber, dairy, etc. This high temperature ORC solution results to be very economically attractive also with other fuels like biomass, waste, coal, etc. The paper will present the technical developments on High Temperature ORC systems and their integration to the complete energy plants, and will provide a general comparison to commercially available alternative technologies.