Biomass-powered micro cogeneration system based on the modified Rankine Cycle operation - the initial tests

Abstract

This paper shows results of initial tests of prototypical microcogeneration system based on the modified Rankine cycle operation. This system is powered by a 100 kW straw-fired batch boiler which was adapted to operate as a high temperature heat source. Thermal oil, heated up to 190-200°C, transfers heat to two shell and tube heat exchangers (evaporator and superheater). Steam powers a 2-cylinder, double-acting, 20-horsepower steam engine. Then, it is condensed in a condenser (another shell and tube heat exchanger) and pumped to the degasser. Finally, condensate is pumped to the evaporator and the whole process starts again. The steam engine is connected with a power generator. The operation of the developed micro-cogeneration system is controlled by the control and measurement system based on WAGO PFC200 PLC controller. The following parameters are recording: temperature, pressure and medium flow (in the boiler, oil, steam and water circuits). The results of the initial tests are promising. Power generated in the system is actually about 1,0 kWel. Such power is sufficient for supplying a part of the system’s equipment. On the other hand, it is finally expected to ensure selfsufficient operation of the tested system.