Thermal and Stress State of the Steam Turbine Control Valve Casing, with the Turbine Operation in the Stationary Modes
Journal Title: Проблеми машинобудування - Year 2019, Vol 22, Issue 2
Abstract
The purpose of this paper is to determine the most stressful zones and assess the possibility of plastic deformations of the control valve casing in its crack forma-tion zones, with the K-325 steam turbine operation in the stationary modes. The problem is solved in two stages. First, the steam flow characteristics in the steam distribution system and the casing temperature are determined. Then, the elastic stress-strain state of the casing of one of the two valve units (through which the steam consumption is always greater than through the other) is esti-mated using the values of the casing temperature field. The characteristics of steam flow in the steam distribution system and the thermal state of the control valve casing are determined numerically by the finite element method. The steam flow rates, temperature and pressure on the casing wall are determined based on the solution to the Navier-Stokes equation in a three-dimensional for-mulation. It is established that the steam temperature before the turbine control valves is practically the same as the one before the stop valve. In the casing itself, after the control valves, with the valves partially open, a significant drop in steam temperature may occur due to throttling. A significant decrease in the steam temperature in the control valve (by 100 °C) is observed at low power with a nominal vapor pressure after the boiler. The calculation of the elastic stress-strain state of the control unit casing was carried out using the finite element method based on the three-dimensional mathematical model for casing deformation. As a result, the stress state of the valve casing was obtained for the different operating modes of the turbine. It is shown that differences in stresses for different modes are associated with changes in the thermal state of the valve casing and the distribution of pressure on its walls. Zones of possible plastic deformations of the valve casing are established. In those zones, the elastic stresses exceed the yield strength of the material. The obtained results clearly show that the most dangerous mode in terms of the control valve casing static strength is not the turbine nominal mode of operation at a power of 320 MW, but a part-load operation mode, at 180 MW.
Authors and Affiliations
Andrii S. Koliadiuk, Mykola H. Shulzhenko
Keywords
Related Articles
- EP ID EP622784
- DOI 10.15407/pmach2019.02.037
- Views 73
- Downloads 0
Use of Computer Technology in Modernization of Head Covers for ПЛ 20-В-500 Kaplan Turbines
<p class="a">One of the problems faced by a designer in the modernization of operating generating units is the analysis of the feasibility of ensuring the strength and reliability of turbine parts and components in their...
Higher order numerical method for aeroelastic problems
The accuracy of determining the conditions for the possible onset of uncontrolled oscillations of turbine blades depends on the accuracy and detail of the aerodynamic problem solution. An increased accuracy of the simula...
Methodology to Solve Multi-Dimentional Sphere Packing Problems
This paper discusses the problem of optimally packing spheres of various dimensions into containers of arbitrary geometrical shapes. According to the international classification, this problem belongs to Sphere Packing P...
Solution of the Structural Optimization Problem of a Multiagent Approach Based Cutter Design
This article proposes a decision support system project to find the optimal milling cutter design. At the preliminary design stage, morphological analysis is used. It allows us to find and systematize all possible millin...
Optimal Design of Bending Elements in Conditions of Corrosion and Material Damage
During operation, many of the critical elements of building and engineering structures are in difficult operating conditions (high temperature, aggressive environment, etc.). In this case, they may be subject to a double...