As an important condition in specific consumption analysis for coal-fired units

the set value basis of fuel specific exergy is not strictly described.Thus

the equivalence relationship between the coal consumption and product specific consumption in thermal units was proved through mechanism analysis

three calculation methods based on different fuel specific exergy modes were deduced

namely taking the actual value

low calorific value and electric equivalent value as the fuel specific exergy.Moreover

through case study on a supercritical 600 MW coal-fired unit

the similarities and differences of the consumption analysis using different calculation basis were quantitatively compared.The results show that

the product specific consumption is the same as the actual value when the fuel specific exergy takes the low calorific value as the calculation basis

and its error is classified into irreversible loss of the combustion process.When the ratio of the fuel specific exergy to the low calorific value increases

the components additional specific consumption distribution and the theoretical minimum consumption will change.However

by using the electric equivalent value as the fuel specific exergy

only the additional specific consumption of combustion process and the total product specific consumption increases.Therefore

taking low calorific value as the fuel specific exergy is the most convenient way and the results are closely related with the conventional energy consumption analysis

which is beneficial to promotion and practice of the theory.