Abstract
The throttling orifice is a common steam pressure reducing equipment and steam flow limiting devices in nuclear power plant, which is used in bypass discharge tank and steam generator. To determine the value of the critical mass flow rate of steam through orifices, several groups of throttling orifices was measured. A 6mm-diameter test orifices was installed in pipes with pipe diameters of 12, 25 and 80 mm. An 8mm-depth test orifices, a 10mm-depth test orifices and a 12mm- depth test orifices, whose diameter all are 6mm, were installed in a same pipe. The 4-hole test orifices with varying orifice diameters of 4, 6 and 8 mm were installed in an 80-mm pipe. A one-hole test orifice, a two-hole test orifice and a 4-hole test orifice, which have the same area of hole, were installed in a same pipe. The critical mass flow of steam with a low degree of superheated through the straight-bore orifices was measured. Within a certain range, the bigger rate of orifice opening, the greater critical mass flow factor; the bigger rate of length to diameter, the greater critical mass flow factor of orifice; the smaller area of hole, the greater critical mass flow factor of orifice. The experimental research can provide reference for the design and optimization of the bypass discharge tank and steam generator.
