Development of two-phase flow dynamic instabilities evaluation technique for sliding pressure once-through boilers

Abstract

In order to improve the load following performance of ultra-super critical sliding pressure once-through boilers, evaporator tubes are required to operate under conditions different from those in the past. However, the conditions for occurrence of density wave oscillation in the multiple parallel tube structure used in the boiler was not clear. Therefore, verification tests were conducted in a condition equivalent to that of an actual boiler, and an evaluation method of flow stability was developed. The test was conducted using water as the working fluid in 4 parallel tubes with an inner diameter of 10 mm and a heating length of 7.4 m. The calculation results by developed evaluation method were in good agreement with the test results.