Exploration • Drilling • Field Services
The selection of rotating equipment for the liquefaction of natural gas
Dr Raja Khan and Dr Kenneth W Ramsden report on software designed to simulate the failure of gas turbine components.
rotating equipment selection for the liquefaction of natural gas (LNG). Tis topical study, included the use of an existing tool developed at Cranfield to aid gas turbine selection through a Techno-Economic, Environmental and Risk Analysis (TERA). Tis tool has seen previous successful applications in areas including civil aviation, power generation and marine propulsion.
T
here has been a recent collaboration between the Department of Power and Propulsion at the UK’s Cranfield University and a major oil and gas company addressing the challenge of
‘in-house’ simulation code called Turbomatch. Tis is a robust and flexible code used to simulate design and off design performance of gas turbines in a range of operational conditions. Simulations can be run at different loads and varying ambient conditions.
Te purpose of this novel tool is to predict the
failure of gas turbine components resulting from observations of the thermodynamic conditions created within the core of the engine. For this reason, both probabilistic and parametric lifting form part of the analysis; looking at failures of hot gas path components such as combustor liners, first stage turbine blades and predicting the life of thermal barrier coatings used on turbine blades. In addition, it is possible to assess the uncertainty involved in defining the likely range of operating life for each component. Tis information is of great use to operators and can aid in better maintenance planning. In the interest of designing plants with high
In particular, the company required the university to investigate its existing LNG liquefaction plants whilst keeping environmental and economic criteria in mind. With mounting pressures of emissions legislation and consequent taxes, there is an ever increasing need to systematically select the most appropriate rotating equipment. Te company, like most, also has many plants where dated equipment needs replacement. Accordingly, a simple to use tool would be highly desirable to aid the procurement process. Against this background, Cranfield’s TERA provides a generic multidisciplinary platform for such an assessment. Te core of TERA is a thermodynamic
performance module simulated using a Cranfield
availability and reliability, the tool uses Monte Carlo simulations to analyse engines on a component-by- component basis. Te measure of availability and reliability is the overall downtime that the Monte Carlo simulations predict. In this way the technology readiness levels (TRL based on the NASA scale) can be linked to the downtime associated with that particular engine, which acts as a quantitative way of measuring reliability and availability. Predictions of emissions like NOx CO2
CO
unburned hydrocarbons and water vapour are also made. Tese indices are then used to calculate emissions taxes given the current local legislation and provides the basis for comparison of the overall global warming potential and carbon footprint of gas turbine engines. Te tool has recently been utilised to analyse a variety of cases and selected results have been published within the American Society of Mechanical Engineers (ASME). ●
Enter 33 or ✔ at
www.engineerlive.com/iog
Dr Raja Khan is former research student of Cranfield University and Dr Kenneth W Ramsden is Consultant to the Department of Power and Propulsion, Cranfield University, Cranfield, Bedfordshire, UK.
www.cranfield.ac.uk
www.engineerlive.com 33
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