This dissertation was carried out at Siemens Industrial Turbomachinery. Placed in the inlet of a steam turbine is a filter, a steam strainer that isolates particles and bigger objects from the steam. These particles and objects can cause solid particle erosion in the turbine assuming they pass by. The steam strainer is subjected to significant pressure drops when clogged, i.e., static loads that demand a good creep resistance in the material. The temperature of the steam inside the turbines is raised to produce more energy; today’s turbines are dimensioned for nearly 600°C. The material in parameters, like the strainer, also needs to be tweaked for the higher temperatures. Temperature is assumed to be the reason for damage in the strainer because the current material might get weak at higher temperatures.The intent of the report is to discover new material for the strainers also to discover a new concept for a way to produce them. There are 9 sizes of steam strainers however only 5 seem to be subjected to the highest temperatures and pressure drops, that make only these 5 exciting to analyze in this thesis. The concepts were chosen based on the method of Ulf Liedholm (1999), Systematic Concept Development. The thesis did not finish up with just a single concept because not every possible method were tested but the recommendations are based on a strainer built from membranes as before.
Contents
1 INTRODUCTION
1.1 THE COMPANY
1.1.1 History of Turbine Production
1.1.2 SIT AB in Numbers
1.2 STEAM TURBINE
1.2.1 Steam Strainer
1.3 AIM AND PURPOSE
1.4 LIMITATIONS
1.5 PRESENT AND FORMER SOLUTIONS
1.5.1 Present Method
1.5.2 Former Solutions Discussed
2 THEORY
2.1 THE MATERIAL
2.2 TO BUILD THE STRAINER
2.3 THE ENVIRONMENT OF THE STRAINER
2.4 SYSTEMATIC CONCEPT DEVELOPMENT
2.5 PRINCIPLES OF THREE POSSIBLE PROCESSES
2.5.1 Electronic Beam Welding
2.5.2 Laser Welding
2.5.3 Brazing
3 METHOD
3.1 CHOICE OF CONCEPT
3.1.1 Phase 1 – Establishing the Design Criterion List
3.1.2 Phase 2 – Establishing the Function Analysis
3.1.3 Phase 3 – Establishing the Concept
3.2 IMPROVING THE STRENGTH
3.2.1 Influences on the Strength from Changes in Design
3.3 EFFECTS OF CLOGGED STRAINER
3.3.1 Influence of Clogging
3.3.2 Recommendation on Percentage Clogging
4 RESULTS
4.1 CHOICE OF MATERIAL
4.2 CHOICE OF CONCEPT
4.2.1 Shrink-fit Rings
4.3 CHANGES IN DESIGN
4.4 DIMENSIONING WITH RESPECT TO LOAD, VIBRATIONS EXCLUDED
4.4.1 Ductile Fracture
4.4.2 LCF – Crack Initiation
4.4.3 Creep
5 DISCUSSION
5.1 MANUFACTURING PROCESS
5.2 THE FE-MODELS
5.3 CHANGES IN DESIGN
5.4 DIMENSIONING AND HCF
5.5 SUPPORTING RINGS
5.5.1 EB-Welding
5.5.2 Brazing
6 CONCLUSIONS
7 RECOMMENDATIONS ON FURTHER WORK……..
Source: Linköping University
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