Contents Issue 02 (2017)

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Use of ODA at Russian Power Plants
Tamara Petrova


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PPChem_2017_19_02_68-74.pdf

The first use of octadecylamine (ODA) in Russia was at the beginning of the 1960s; extensive investigation of ODA properties started in the 1970s. The following topics were studied: thermolysis of ODA in water environments, sorption of ODA on metal surfaces, the effect of ODA on the corrosion rate, the washing power of ODA, the volatility of ODA, and the effects of ODA on the composition of deposits. This contribution summarizes the results of the research conducted in Russia over the last decades.

PowerPlant Chemistry 2017, 19(2), 68–74
Repeat Cycle Chemistry Situations: Precursors to Future Damage in Industrial Utility Plants
Kevin J. Shields


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PPChem_2017_19_02_77-85.pdf

Chemistry-related damage events in fossil utility steam generators and steam turbines can be linked to operation with certain repeat cycle chemistry situations. When multiple repeat cycle chemistry situations are present, the risk of future damage is significant. Repeat cycle chemistry situations should be regarded as root causes of damage mechanisms. Application of the repeat cycle chemistry situations philosophy to an industrial cogeneration facility is presented as a case study.

PowerPlant Chemistry 2017, 19(2), 77–85
Understanding Variations in Flow-Accelerated Corrosion Wear Rates in HRSG Evaporator Tubes
James Malloy, Jan Rusås, and Mark Taylor


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PPChem_2017_19_02_92-102.pdf

Very large differences in the rates of tube wall thinning due to flow-accelerated corrosion (FAC), or in some cases fluid erosion, are observed in the low-pressure (LP) evaporator tubes of certain HRSG designs. The tubes located near the duct wall and occasionally near the gaps between module bundles have more rapid thinning. Tubes in a given row nominally should have very similar process conditions, both on the gas-side and on the waterside. Different wall thinning rates mean that process conditions differ across the tube row.

Computational fluid dynamics (CFD) simulations have been used to investigate the gas-side process conditions in tube assemblies and to determine the impact of tube location in the row on heat transfer. The impact of differing tube heat fluxes on waterside process conditions was analyzed by thermohydraulic simulations using a computer model of the tube assemblies. A correlation between increased thinning rates as a function of tube position and LP evaporator process conditions was identified.

PowerPlant Chemistry 2017, 19(2), 92–102
Internal NDT Inspection of HRSG Finned Tubes
Damien Pain, Agnieszka Kuczynska, and Fraser Hardie


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PPChem_2017_19_02_104-113.pdf

Boiler tubes, which are a predominant feature of heat recovery steam generator (HRSG) pressure parts, can be susceptible to various degradation mechanisms. The range of defects, including flow-accelerated corrosion (FAC), pitting corrosion and fatigue cracking, can cause unpredicted in-service failures. HRSGs have by design a reduced footprint and this compact design imposes severe access restrictions for inspection. There are no established, offtheshelf, internal inspection solutions for finned tubes. Doosan Babcock conducted a 3-year (2014–2016) project aimed at developing a tube inspection product for use in plant life assessment to help establish the life expectancy and maintenance requirements of customers' assets. The challenge was to develop a qualitative and quantitative nondestructive testing (NDT) technique which can be remotely deployed on HRSG headers through standard inspection stubs during an outage.

In this paper, an eddy current near field array (NFA) is used to generate an image, called a C-scan, absolute traces and Lissajous patterns to characterise the internal integrity of HRSG finned tubes. The method is demonstrated on finned tube samples with experimental work conducted in a laboratory controlled environment. It is shown that indications can be successfully detected and sized using a clearly defined post-processing strategy.

PowerPlant Chemistry 2017, 19(2), 104–113
  
  
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Last updated: 07.04.2017