Some perspective decisions for the regeneration system equipment of the thermal and nuclear power plants decreasing the probability of water ingress into the turbine and rotor acceleration by return steam flow

Abstract

The regeneration system heaters are one of the sources of possible ingress of the water into the turbine. The water penetrates into the turbine either at the heaters overflow or with the return flow of steam generated when the water being in the heater boils up in the dynamic operation modes or at deenergization of the power-generating unit. The return flow of steam and water is dangerous to the turbine blades and can result in the rotor acceleration. The known protective devices used to prevent the overflow of the low-pressure and high-pressure heaters (LPH and HPH), of the horizontal and vertical heaters of heating-system water (HWH and VWH), as well as of the deaerators and low-pressure mixing heaters (LPMH) were considered. The main protective methods of the steam and water return flows supplied by the heaters in dynamic operation modes or at deenergization of the power-generating unit are described. Previous operating experience shows that the available protections do not fully prevent water ingress into the turbine and the rotor acceleration and, therefore, the development of measures to decrease the possibility of ingress of the water into the turbine is an actual problem. The measures allowing eliminating or reducing the water mass in the heaters are expounded; some of them were designed by the specialists of OAO Polzunov Scientific and Development Association on Research and Design of Power Equipment (NPO CKTI) and are efficiently introduced at heat power plants and nuclear power plants. The suggested technical solutions allow reducing the possibility of the water ingress into the turbine and rotor acceleration by return steam flow in the dynamic operation modes or in the case of power generating unit deenergization. Some of these solutions have been tested in experimental–industrial exploitation and can be used in industry.