Pinch and exergy analysis of lignocellulosic ethanol, biomethane, heat and power production from straw

In this work a complex process for production of bioethanol, biomethane, heat and power from the wheat straw is introduced and analyzed with regard to pinch and exergy analysis. The pinch analysis is focused on the bioethanol production where a well-designed heat exchanger network increases heat integration up to 45 MW. To obtain optimal total site external hot and cold utilities demands at different temperature levels as well as maximum power generated by steam turbine, an integrated steam cycle composite curve has been added to the grand composite curve of the “background process”. The exergy analysis takes into account three production sections separately and exergy efficiencies are calculated to find the quantity of irreversibilities the bioethanol processes. The results from exergy analysis show that the bioethanol process has the highest exergy efficiency because of usage of stillage for other processes in which a considerable part of exergy entering is converted into irreversibility because of heat losses and non reacting unknown material produced as material losses.