In order to realize energy conservation and emissions reduction

the generating heat consumption rate of the steam turbine under various load conditions need to be reduced.It is generally thought that the nozzle adjustment is helpful to the unit low load operation

thus a large amount of units apply the nozzle adjustment mode.In this paper

by taking two(ultra)super critical 600 MW units as the example and combing with the test data

the energy saving effects of the unit employing different adjustment methods during slide pressure operation were compared

according to the steam loss characteristics.The results show that

for large scale units in slide pressure operation under various load conditions

the HP cylinder efficiency with throttling nozzle regulation was about 4.36% to 5.50% higher than that with nozzle regulation

and the heat loss rate was about 130kJ/(kW·h)to 160kJ/(kW·h)lower.At low load conditions

the HP cylinder efficiency increased more obviously and the heat loss reduced more dramatically.The nozzle adjustment is only suitable to constant pressure operation or small steam turbine operation.