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Almasi A.,WorleyParsons Services Pty Ltd
Chemical Engineering | Year: 2012

A guidance to improve lubricant selection, whether mineral oils and synthetic oils, process operation and asset reliability is discussed. Mineral oils are more frequently used in chemical process industries (CPI) applications. Synthetic oils offer superior performance in terms of higher oxidation stability, improved corrosion resistance, and the ability to withstand both higher and lower temperatures. When selecting a lubricant for reciprocating or screw compressors, low solubility in compressed gas should be a key selection criteria. For reciprocating or screw compressors, the lubrication oils that meet all of these criteria are mainly synthetic lubricants formulated with PAG base stock. PAG lubricants show less than 20% of the water solubility of typical mineral oils. Synthetic lubricants with ISO VG 100 to 220 ratings are extensively used for reciprocating compressor cylinder packing for process services. Turbine lubricants must have excellent thermal and oxidation resistance at bearing oil temperatures.

Almasi A.,WorleyParsons Services Pty Ltd
World Pumps | Year: 2012

The sudden failure of a pump component can have serious and costly consequences. Amin Almasi considers the failure modes in a pump's rotating assembly, including resonance issues, fatigue failures, vibration, the chain of events and secondary damage to critical auxiliaries. The discussion is illustrated with case studies. © 2012 Elsevier Ltd.

Yip K.,Curtin University Australia | Ng E.,Curtin University Australia | Ng E.,WorleyParsons Services Pty Ltd | Li C.-Z.,Curtin University Australia | And 2 more authors.
Proceedings of the Combustion Institute | Year: 2011

This paper provides mechanistic insights into the low-temperature oxidation of a range of carbon materials (graphite, a sub-bituminous coal char, and a brown coal char). Kinetic analysis was carried out on oxidation of the chars, prepared from fast-heating pyrolysis, under chemical-reaction-controlled regime. FT-Raman spectroscopic analysis was adopted to provide direct structural information on the carbon structure of reacting carbon materials throughout oxidation. The results demonstrate the significance of selective oxidation under the conditions, and parallel to this, the kinetic compensation effect of carbon oxidation reaction throughout conversion for all samples. Supported by the results from FT-Raman spectroscopy, the kinetic compensation effect seems to be a result of the selective oxidation of these carbon materials with heterogeneous carbon structures. Oxidation of all samples, with or without catalysts, appears to be similar in terms of the 'nature' of carbon structural condensation during low-temperature oxidation, suggesting a similar increase in apparent active sites population with respect to increase of apparent energy barrier. Under the current experimental conditions, a general kinetic compensation effect correlation has been deduced for various materials, requiring only the initial char kinetic parameters. The inherent inorganic species in chars also seem to alter the 'degree/extent' of carbon structural condensation as results of selective oxidation. In this case, the use of the compensation effect correlation will require more information on the catalysis during oxidation, apart from the initial char kinetic parameters. © 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Almasi A.,WorleyParsons Services Pty Ltd
Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy | Year: 2013

The purpose of this article is to provide new practical guidelines on rotordynamics and stability analysis of power generation trains. Latest methods, modern recommendations, recent lesson learned and new practical notes on power generation machinery rotordynamics are presented. Critical areas relative to safety and reliability of power generation machine design and component selection including the bearing dynamic effects, the rotordynamics study/modelling methods, the third party analysis, the gear unit dynamic and potential instability sources are discussed. The main concern is the correct design and dynamic study of a power generation train before the equipment fabrication and the component sub-supply started and for some issues even before the train order. Case studies are also presented. © IMechE 2013.

Almasi A.,WorleyParsons Services Pty Ltd
Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering | Year: 2012

A new study for laminated composite rotating disk fabricated from symmetric sequential quasi-isotropic layers to predict three-dimensional (3D) stress and deformation is addressed. It is used to evaluate the mechanical stress and integrity of fibre reinforced multi-layer laminates used for ultra high-speed impellers of modern process centrifugal compressors. Composite laminates are relatively weak in out-of-plane loading, inter-laminar stress, stress concentration near the edge, and stress singularities. 3D stresses and deformations shall be investigated for laminated composite rotating disk applications. © Authors 2011.

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