Design optimization and analysis of a multi-temperature partition and multi-configuration integrated organic Rankine cycle for low temperature heat recovery

•An improved multi-temperature partition and configurations ORC system is proposed.•An optimization strategy framework designed for MMORC system is presented.•The influence of key variables on MMORC system performance is discussed.•An actual refinery case is applied to the proposed MMORC system.•The efficiency is improved by 4.95 % and economic performance is improved by 1.45 %.