Taking a 9Funit as the example

the changes rules of steam parameters in high and low pressure system and the heat recovery steam generator(HRSG)efficiency with the flow rate of extracted steam were investigated

when the steam was extracted from different positions(the high pressure(HP)cylinder and the intermediate pressure(IP)cylinder)

under the same steam extraction condition.The results show that

when the steam was extracted from the HP cylinder

the steam flow and pressure in HP system increased with the extraction steam flow

while that in the LP system changed in opposite.When steam was extracted from IP cylinder

the HP steam flow and pressure hardly changed with the variations of extracted steam flow

while that in LP system increased with the extracted steam flow.Whether the extraction position was the same or not

the heat efficiency of the HRSG increased with the extracted steam flow

and the heat efficiency growth rate rose faster when the steam was extracted from the HP cylinder.