By using the mixed grey associated hierarchical analysis method

the comprehensive evaluation of four co-generation schemes for the residual heat utilization of high-temperature flue gas from the heating furnace of one steel rolling mill has been carried out.The weight of four indices

i.e.payback period of the investment

utilization ratio of the total energy

decrement of CO2

emission

and convenience in maintenance

has been calculated by using the hierarchical analysis theory

and the evaluation matrix being determined by using the mixed analysis method

the comprehensive judgement being completed through weighted summarization.The sequence of optimized selection for residual heat utilization scheme of high-temperature flue gas from heating furnace of said steel rolling mill is as follows:heat and electricity co-generation

cool

heat

and electricity co-generation;cool and heat cogeneration;electricity generation using waste heat.The said evaluation method can also be used for other evaluation systems with multi-attribute.