Modernization of heat exchangers in steam turbine units taking features of their operation at specific thermal power plants into account

Abstract

The authors' experience in the modernization of commercial heat exchangers in steam turbine units is discussed with the individual features of the operation of these exchangers at specific thermal power plants taken into account. The variety of conditions under which heat exchanges operate in specific engineering subsystems requires an individualized approach to the model solutions that have been developed for modernizing these systems. New piping systems for commercial heat exchanges have undergone industrial testing and are in successful operation at a wide range of thermal power plants.Extending the service life and increasing the operational efficiency and reliability of heat exchangers in steam turbine units at thermal power plants are of great current interest [1,2]. Modernizing heat exchangers operating at thermal power plants involves less expense than replacing the entire heat exchanger and is mainly aimed at eliminating structural defects that have been identified. This is done both when worn out components are replaced and in the course of planned major overhauls, so that the efficiency and operational reliability of the heat exchangers and the steam turbine unit, as a whole, can be increased substantially.The major engineering solutions for improvement of commercial heat exchanger units in the steam turbine units of thermal power plants must, first of all, be directed at raising the efficiency and reliability of their piping systems, since they are the most subject to wear during operation [1 -5]. The choice of approaches and modern engineering solutions for the improvement of heat exchangers must meet a number of specifications, including:-accounting for the specific operating conditions; -raising the efficiency of the heat exchanger while retaining reliability or increasing reliability while maintaining efficiency; -improving or sustaining repairability and maintainability; and, -meeting the standards and rule of the supervisory agency Rostekhnadzor.The improvement of heat exchangers is a rather complicated system problem. A large number of factors at different levels which influence the efficiency and reliability of a heat exchanger have to be taken into account, along with its relationship to the engineering subsystems of the steam turbine unit of a thermal power plant [1 -5]. The choice of a modernization scheme involves solving a specific optimization problem where the target function or criterion determining the choice may be any of various characteristics, such as raising the thermal efficiency or the thermal capacity of the heat exchanger, or increasing its operational reliability or repairability [1].It has been shown [1 -3] that determining the approach for improving a heat exchanger can be divided structurally into three stages: a stage for analyzing the initial data, a stage of computations and accounting for a number of operational and design-engineering factors, and a stage of technical and economic analysis and validation. One of the most important stages in the analysis is the use of ...

Modernization of Steam Turbine Heat Exchangers Under Operation at Russia Power Plants

“…It depends on the following factors: the influence of heat cycles in different directions, the inherent and forced vibrations of the tubes in the bundle and in the apparatus as a whole, the corrosive effect of the cooling water, the natural aging of the material of tubes and tube sheets, etc. [1,2].…”

“…The choice of approaches and modern engineering solutions for heat exchangers improvement must meet a number of specifications including the following [1]:…”

“…Over many years the authors have proposed, tested and brought to realization a series of new, by now commercial, technical solutions for modernizing a large number of different heat exchangers for steam turbine units; these have provided satisfactory solutions of the problems arising during heat exchanger operation, such as [1][2][3]:…”

Numerical modelling of series-parallel cooling systems in power plant

“…It is also worth mentioning that the deterioration of the overall power unit efficiency results in the greater consumption of fossil fuels and consequently higher CO2 emission (as well as that of other pollutants) [2]. Keeping in mind that the improvement of heat exchange processes could have a direct influence on the overall efficiency of a power unit, Ryabchikov et al in [3] suggested a number of specific actions, among which the retrofit of cooling water installations is one of the most important.…”

Single-phase media hydrodynamics and heat transfer in heat exchangers with twisted profile tubes

“…In TPT tube systems both oscillation amplitude and stress values (in tube and tube sheet junctions) are lower than in the plain tube apparatuses. So in terms of the TPTs vibration characteristics higher reliability can be achieved by a proper tube partition design in TPT apparatuses according to Ryabchikov et al [1].…”