![]() ![]() Pressure in the primary circuit of PWRs is maintained by a pressurizer, a separate vessel that is connected to the primary circuit (hot leg) and partially filled with water which is heated to the saturation temperature (boiling point) for the desired pressure by submerged electrical heaters. The exhausted steam is at a pressure well below atmospheric, and is in a partially condensed state (point F), typically of a quality near 90%.Ī pressurizer is a key component of PWRs.Ī pressurizer is a component of a pressurized water reactor. The reheater heats the steam (point D) and then the steam is directed to the low-pressure stage of steam turbine, where expands (point E to F). To prevent this, condensate drains are installed in the steam piping leading to the turbine. High content of water droplets can cause the rapid impingement and erosion of the blades which occurs when condensed water is blasted onto the blades. The steam must be reheated or superheated in order to avoid damages that could be caused to blades of steam turbine by low quality steam. ![]() In these turbines the high-pressure stage receives steam (this steam is nearly saturated steam – x = 0.995 – point C at the figure) from a steam generator and exhaust it to moisture separator-reheater (point D). ![]() Typically most of nuclear power plants operates multi-stage condensing steam turbines. The process of superheating in the T-s diagram is provided in the figure between state E and saturation vapor curve. In the superheater, further heating at fixed pressure results in increases in both temperature and specific volume. This requires the addition of another type of heat exchanger called a superheater, which produces the superheated steam. The process of superheating is the only way to increase the peak temperature of the Rankine cycle (and to increase efficiency) without increasing the boiler pressure. In order to evaluate the cycle thermal efficiency the enthalpy must be obtained from the superheated steam tables. As can be seen also wet steam turbines use superheated steam especially at the inlet of low-pressure stages. The process of superheating of water vapor in the T-s diagram is provided in the figure between state E and saturation vapor curve. Rankine Cycle – Thermodynamics as Energy Conversion Science Actually, the substances we call gases are highly superheated vapors. The pressure and temperature of superheated vapor are independent properties, since the temperature may increase while the pressure remains constant. Superheated vapor or superheated steam is a vapor at a temperature higher than its boiling point at the absolute pressure where the temperature is measured. The dry saturated vapor is characterized by the vapor quality, which is equal to unity. If a steam exists entirely as vapor at saturation temperature, it is called saturated vapor or saturated steam or dry steam. The saturated liquid curve is the curve separating the subcooled liquid state and the two-phase state in the T-s diagram. ![]()
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