This thesis is focused on the application of advanced methods for evaluating damage to boiler tubes, specifically temperature related damage. The aim of this work is to develop an improved damage evaluation procedure utilizing capabilities of modern approaches. This work describes various types of industrial boiler damage. The main focus is on the most exposed and often the most damaged parts of boilers, which are tube bundles (for example, superheaters). Equipment damage is undesirable and often leads to leakages or even to the boiler shutting down. Therefore, it is necessary to find the problem as soon as possible and make the required changes to prevent further damage. The damage types are divided into five categories based on the damage mechanism. Temperature has one of the biggest influences on damage and it may cause short-term or long-term overheating in the tube bundles. This type of damage occurs when the designated temperature is exceeded and results in reduced creep life. It is necessary to know the real surface temperature history of the tube bundle to estimate temperature related damage, however this is often not available. Therefore, it is necessary to calculate those temperatures based on the available data (i.e. inlet and outlet temperatures and pressures). This is real challenge due to the combination of complex flows of the working substances (mainly flue gasses) and heat transfer. Considering available data, new approach is proposed in order to obtain information required for residual creep life estimation. In the first step, thermal – hydraulic calculation is performed followed by a thermal load estimation of a superheater tube bundle in a natural gas fired boiler, using CFD simulations. In the next step, the surface temperature is evaluated and used to determine the temperature related damage, specifically the creep life estimation. The life expectancy is in some ways influenced by imperfections, and therefore at the end of this thesis the influence of the oxide layer on the inner side of tube and fouling on outer side of tube is described.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:411058 |
| Date | January 2019 |
| Creators | Naď, Martin |
| Contributors | Odstrčil, Miloslav, Jůza, Zdeněk, Jegla, Zdeněk |
| Publisher | Vysoké učení technické v Brně. Fakulta strojního inženýrství |
| Source Sets | Czech ETDs |
| Language | Slovak |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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