Against the backdrop of the "dual-carbon" goals and the new power systems

coal-fired power generation is accelerating its transition toward deep and flexible peak-shaving. However

when coal-fired units operate at low-load conditions

prominent challenges including substantial degradation in safety and reliability as well as sharp growth in coal consumption remain to be addressed. To this end

this study systematically elaborates the theoretical methodology of thermodynamic system reconstruction

analyzes its influences on boiler combustion stability

hydrodynamic characteristics

heating-surface metal safety

and emission control under low-load conditions

and discusses its improvement effects on heat consumption at low loads. By establishing a correlation mechanism of "key performance-characteristic parameters-key-component structures"

the proposed theoretical methodology employs modular thermodynamic system topology control and flow-field reconstruction to raise characteristic parameters such as feed-water temperature

main-steam pressure

and steam flow-field under low-load operating conditions to levels close to their rated values. Research on a 1000 MW ultra-supercritical unit shows that

at 30%~50% rated load range

this technology can increase feed-water temperature

the flue gas temperature for selective catalytic reduction (SCR) denitrification and hot air temperature by approximately 65 ℃

44 ℃ and 30 ℃

respectively

significantly improving key performance indicators including low-load combustion stability

hydrodynamic and heating-surface safety

and SCR reliability. Meanwhile

it reduces the net coal consumption for power supply by 8~27 g/(kW·h)

offsetting about 55% of the coal-consumption increment of conventional units at low-load operation. Conducting research on turbine ultra-low load operation technology based on this theory represents an important development direction for flexible coal-fired power thermodynamic systems.