Under the impetus of the“dual carbon”goals

300 MW-class subcritical wet-cooled units are facing multiple challenges such as a sharp decline in hourly utilization

the need to undertake deep peak shaving tasks

and heating coupling.Against this backdrop

implementing flow path retrofit is regarded as one of the most economically beneficial approaches.It takes the flow section and flexibility transformation of Unit 1 of a certain thermal power plant as an example

systematically expounds the key technical system of “high-efficiency 3D blades+integral inner casing”

and establishes an integrated evaluation method of “testing-correction-benchmarking”.The performance evaluation results show that under the turbine heat acceptance condition

the heat rate of the unit decreases from 8139 kJ/kWh before the transformation to 7706 kJ/kWh

with a reduction rate of 5.3%.The weighted heat consumption rate is 7854 kJ/kWh

which is 10 kJ/kWh lower than the guaranteed value.In terms of cylinder efficiency

the efficiency of high-pressure cylinders increases by 4.3%

that of medium-pressure cylinders by 1.8%

and the improvement rate of low-pressure cylinders reaches 7.7%.In addition

during the heating period

achieving 20% load deep peak shaving operation is expected to save 25 500 t of standard coal and reduce carbon dioxide emissions by 63 500 t annually.The technical path and evaluation system proposed have reference for the transformation and upgrading of similar units.