Thermodynamic evaluation and optimization of organic rankine cycle integration for waste heat recovery to Afyon biogas plant

Abstract

The increasing need for energy day by day has directed human beings from fossil fuels used as primary energy sources to alternative sources. However, fossil fuels are expensive, harmful to the environment, and will be used up soon, so, searching cheap, sustainable, and environmentally friendly fuels has become inevitable. In this respect, biomass stands out. The use of biomass in energy transformation is one of the focal points of sustainable energy. Especially in regions where agriculture and animal breeding activities are common, chicken manure, agricultural waste, slaughterhouse waste can be used in energy conversion. These energy resources are digested in an oxygen-free environment, and biogas is produced. The biogas produced is burned in the power plant to generate electricity. In this study, an integrated ORC (Organic Rankine Cycle) has been designed to recover low-grade waste heat in the Afyon Biogas Power Plant producing biogas from chicken manure. Also, a thermodynamic performance evaluation of the cogeneration plant has been investigated, which will increase the net power generation from biogas. The power production and performance values have been investigated using the exhaust gases between 400 and 700 °C in the ORC of the biogas power plant with 4 000 kW capacity and four gas turbines. The maximum net work capacity of the plantassisted ORC has been determined as 4 719 kW. The plant has been operated with optimum working conditions, energy and exergy efficiencies have been calculated as 40.31% and 45.48%, respectively.