Husk-Fueled Steam Turbine Cogeneration for a Rice Mill with Power Export-A Case Study

Utilization of the husk-fueled cogeneration system to meet the requirement of thermal and electrical needs enhances the energy efficiency and production capacity of rice mills. This will not only result in considerable savings but also leads to a sustainable supply of electricity and additional revenue from the surplus electricity generated from saved rice husk. This article presents a case study that was conducted in a South Indian rice mill in order to study the technical and economic feasibility of implementing a steam turbine-based cogeneration with an option for power export. In the proposed scheme, the existing boiler will be replaced by a new one of higher capacity. By means of a steam turbine topping cycle, electricity is generated and the turbine exhaust steam is utilized for heating applications. It has been found that the introduction of cogeneration will enhance the rice production by a minimum of 30 tons per day. Furthermore, the proposed system in its full time operation could yield an annual savings of about INR 4 million ($0.12 m) compared to the existing facility and the additional investment would be paid back within a period of three years.