The Research On Method Of Measuring Steam Wetness In Nuclear-power Plant Turbine Based On Double-region-heating

With the development of Power industry, some equipment which use wet steam as medium in the low-pressure stages condensing turbine nuclear-power plant turbine, geothermal power plant turbine. Wetness of steam exist in turbine not only decrease the efficiency of turbine but also erode the leaves, make economy down and menace the safety of unit. So the state of steam flow which in the turbine of steam-region, distributing of radial wetness and diameter of drip will be ascertained from the exact measurement of steam wetness. Further more the efficiency of turbine will be ascertained and the operation will be instructed. The steam wetness also provide a plan for design of turbine and drain.The thermodynamic is based on energy conservation theory to measure steam wetness. The researches are earlier and the technology is developed. The thermodynamic has the advantage of simple principle, high precision and convenient use. Its'disadvantages are being conquered. Though, it can not measure diameter of drip, it still a appropriate method.Double-region-heating has the advantage of simple principle, high precision and it is a appropriate on-line method for measuring the wetness of exhaust in turbine in the thesis based on summarizing lots of measures and analyzing two-phase flow,engineering thermodynamic principles. The thesis aims at on-line monitoring the wetness of exhaust in turbine. The principle of double-region-heating and the source of error are analyzed, mathematical model is established, formulae are developed. Double-region-heating adopts heating at exterior of the tube and includes evaporative section and superheated section. The saturate steam is heated to superheated steam with higher superheated degree. By measuring the temperature and press in the entrance of evaporation section and exit of superheated section, we can get the humidity according to formula. At the same time, superheated section is used to measure the steam flux instead of equipment, the system is simplified. The structure of probe and measuring system are designed and analyzed in the thesis. It provide principles for making actual probe. The thesis applied arithmetic recursive estimation and batch estimation data fusion algorithm to double-region-heat measuring system. From programs, the arithmetic recursive estimation and batch estimation data fusion algorithm are confirmed is correct.