Enhancing Oil and Gas Production Through Improvements in Gas Turbine Cleanliness
machine overhauls. Inspections of engines employing HEPA quality air showed a massive improvement in hot end condition with results for one Rolls Royce RB211 machine in the UK North Sea recording 84,000 hours of hot gas path life.
Environmental Benefits
The World Bank estimates that over 150 billion cubic metres of natural gas is flared or vented annually, an amount worth approximately 30.6 billion dollars, equivalent to 25% of the gas consumption of the US or 30% of the European Union’s gas consumption per year.1
A turbine
operating parts with improved condition is also less likely to incur a trip and force an unplanned shutdown. This benefits the engine itself as emergency shutdowns are factored into the engines useful life, but also annual gas flaring is reduced benefiting to the operator environmentally by reducing emissions and since flared gas could have otherwise been directed to the consumer.
Economic Payback
Experience has shown that while HEPA filters are more expensive and the inlet system often has to be designed to achieve the best solution, the benefits are huge in comparison (see Table 1). Extended hot-end component life, improved availability and increased revenues can potentially reduce filter pay-back time to days. It is proven that air quality can be provided that is in excess of traditional levels used on rotating machinery. This has huge financial and technical benefits that greatly
It must be considered that long hot-end component life has not always been in the interest of all parties in the supply chain of capital equipment. The industry has not always recognised the benefits of high-quality air filtration. It is also important to note that even higher air quality than H12 can be provided, which is far in excess of anything required by rotating machinery. European test standards, EN779 and EN1822 together list 17 grades of filter efficiency from G1 through to U17. The operational cost example quoted earlier improved the system efficiency by a factor of x1,000, stepping up from F7/F8 to H12.
Conclusion
While modern HEPA filters have to be specifically designed for use in GTs, industry is not stretching the capabilities of air-filtration technology. It can benefit from the technology without risk. The ambition of an operator may be to remove the need to offline and online wash rotating and static components to maximise production or to enhance machine output. Either way, HEPA-class filtration or, more accurately, clean air delivered consistently and reliably offers the turbine user realisable and proven benefits that can be reduced to a set of assured economics. n
1. The World Bank, World Bank, GGFR partners unlock value of wasted gas, The World Bank, 2009. Available at:
http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTSDNET/0,,contentMDK: 22416844~menuPK:64885113~pagePK:64885161~piPK:64884432~theSitePK:5929282,
00.html (accessed 17 March 2010).
exceed the additional capital cost and the cost of the consumable filters. In summary, clean air can advantageously change the economics of turbo-machinery operation through better machine availability, lower operating costs, longer hot-end component life, more predictable performance and improved preventative maintenance.
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