High pressure steam–water two-phase flow measurements by flow division and separation method

This paper proposes a method for high pressure steam–water two-phase flow measurements by flow division and separation. The flowrate of a steam–water mixture is metered by diverting a small fraction (about 2%) of total mass flow to a division loop, where the diverted mixture is separated into steam and water flows by means of a small separator and they are metered with single-phase flow meters respectively. The metered values are then converted to total flowrates according to the extraction ratios. The first equation of the extraction ratios was derived from the relation of resistance between the main loop and the division loop, and the second equation of the extraction ratios was developed from the distribution characteristics of the division loop. The extraction ratios were then determined by solving these two equations. Experiments were carried out in an once-through boiler for steam flooding. The inside diameter of pipe was 50 mm, and the experimental flowrate ranged from 2000 kg/h to 8000 kg/h, the steam mass quality varied from 60% to 81%, and pressure ranged from 7.6 MPa to 16 MPa. Experiments show that the flow division and separation method is a reliable technique. The flowrate measurement error is less than ±2.5%, and the steam quality measurement error is less than ±3.5%.