Based on analysis of feed water flow measurement deviation in once-through boiler

measurements were taken as follows:adopting independent sampling of feed water flow;using positive pressure side second valve

negative pressure side second valve and balance valve that composed of needle type valve set which can bear pressure more than 40 MPa to replace three valve groups

and to connect to junction of positive pressure side and negative pressure side by screw adding gasket;increasing heat tapes of pipeline.Meanwhile

to measure the feed water flow accurately

it should be ensured that

the sampling devices are arranged reasonably

the sampling pipeline has no leakage

and measurement range of the transmitter is consistent with that of the I/O channel in DCS

furthermore

the DCS data transmission channel is normal.After the treatment

feed water flow deviation values measured at three points were less than 50t/h.