The tradifional measurement methods of main steam flow rate and the problems existing in said methods have been pointed out

an on-line monitoring system of main steam flow rate from steam turbine based on the main condensate flow rate being put forward.The selection of base flow rate

and the disposal of small steam-water flow

i.e.the leakage of sealing water from feed-water pump

and the leakage of steam from by-pass valve of high-pressure heater

as well as the realization of said on-line monitoring have been analysed.The said system has been used in main steam flow rate calculation of one 200 MW steam turbine unit

and a comparison of the calculated value with that of convintional methods being carried out

the result shows that the said system has the capability of realtime acquiring and processing of data with highter accuracy

can satisfy the requirements on the main steam flow rate in engineering applications

such as real-time calculation for diagnosis of unit's economic efficiency

and on-line load distribution optimization etc..