There is great controversy in calculation of energy saving benefit in design and test of turbine-boiler deeply coupled system

which is mainly due to the inaccuracy of boiler efficiency calculation or definite value.Several roots of the problem are analyzed

and discussed from the aspects of theory and application. Problems of engineering application projects and the Calculating Method of Energy Saving for Flue Gas Waste Heat Cascade Utilization System in Thermal Power Plants(DL/T 2169 — 2020) are analyzed. It points out that

their's misunderstandings when the boiler efficiency calculation method of the current standard is applied to the turbineboiler deeply coupled system. The integrated calculation rule of “mass-balance/heat-balance/heat-transfer”

criterion index of “equivalent comparable exhaust gas temperature”

and the concept of taking “boiler efficiency and turbine heat consumption coupling” as the basis of overall energy saving benefit evaluation

provides a new idea for studying and solving the problem of the inaccuracy of calculation/definite value of boiler efficiency. The research results of this paper provide a reference for guiding the practical work

and also has a prompt significance for correctly formulating relevant regulations

specifications and applications.