State of the Art and Trends in the Design and Operation of High- and Low-Pressure Heaters for Steam Turbines at Thermal and Nuclear Power Plants in Russia and Abroad: Part 2. Heater Design and Operation Peculiarities

Abstract—

The modern state of the processes connected with design, calculation, and operation of heaters used in steam turbine regeneration systems is reviewed and analyzed on the basis of data available from domestically published and foreign sources. The existing methods for thermal–hydraulic, strength, and vibration design calculations of apparatuses are described; criteria adopted in designing individual areas of heater heat-transfer surfaces are mentioned, and recommendations on taking into account the heat-transfer surface fouling in analyzing its influence on the apparatus’s thermal-efficiency indicators are given. The possibility of using modern computation tools for designing regeneration system apparatuses is considered. A list of materials from which the apparatus heat-transfer surface tubes are made is given; methods for fixing them in shell-and-tube heaters are mentioned, and the level of stresses recommended for individual tube sections is pointed out. The values of key operating parameters—coolant temperatures, pressures and velocities—are given, which are selected based on the results of designing the apparatuses and with reference to foreign standards and other regulatory documents. Recommendations used by foreign manufacturers of heaters as guidelines for selecting vibration-safe length of free spans and tube fastening methods in the bend zone are given. Failures that most frequently occur during operation of high- and low-pressure heaters are pointed out. Some questions concerned with the technology for repairing the regeneration system heaters used as part of a turbine plant are considered. It is shown that there are differences in arranging the repair system and, especially, in the maintenance of heat-transfer apparatuses as concerns the tools necessary for monitoring the equipment condition. The introduction of new technologies for designing and operating heaters in domestic practice will help keep their efficiency and reliability indicators at a high level.