Turbine oils: Unlocking efficient, reliable power

Understanding how lubricants contribute to total cost of ownership is the primary step to realising potential savings, argues Dr Peter Smith

Power Engineering International April 2017

In power, every day is critical. When people flick a switch, they expect the power to be there instantly.

This places power companies under immense pressure to ensure reliable, efficient operations, in a challenging climate of stricter environmental targets, severe penalties for supply interruptions, tighter budgets and tougher operating conditions.

Today’s power generation turbines are working under more demanding conditions than ever – from continuous 24/7 running, to frequent stop-start cyclic operation to accommodate fluctuating power generation.

As a result, modern turbine oils must be able to cope with increased stress and considerable design and operational challenges, including reduced downtime, extended oil drain intervals, higher temperatures and loads.

Greater turbine output power, combined with a lubricant reservoir that is the same size or smaller, is also imposing more rapid cycle times on lubricants, resulting in the need for excellent surface properties.

Lubricant samples for testing
Lubricant samples for testing
Credit: Shell

Lubricant product selection or management can impact many elements of a company’s maintenance budget. Seizing the cost-saving opportunity depends on addressing two equally important elements.

Firstly, it’s important to select the right lubricant. Turbine oils need to help deliver value through extended oil and asset life, enhanced equipment protection and excellent system efficiency.

Looking at the ratio of turbine megawatt output to oil volume gives an indication of oil stress, and increases are being seen of up to 400 per cent with the latest turbines. This is having a big impact on the types of lubricants required by power generation customers.

By selecting a high performing oil, power sector companies can realise total cost of ownership (TCO) savings that reach far beyond any savings related to the price of the lubricant itself.

Selecting a less effective lubricant rarely results in immediate equipment failure, but can lead to increased maintenance expenses over time and, in the event of disruptions from unplanned downtime, heavy financial penalties. These mounting costs can be far greater than the savings from selecting a lower price lubricant.

In contrast, a high-performance, high-quality lubricant that keeps equipment clean of deposits, and effectively protects against wear and corrosion and other lubricant-related problems can help extend equipment life, reduce frequency of breakdown and increase equipment availability. This could significantly decrease spend on spare parts and maintenance over the life of the asset.

A laboratory technician tests lubricants to maintain quality control
A laboratory technician tests lubricants to maintain quality control
Credit: Shell

However, the potential impact of lubricants is often significantly underestimated. There is potential for lubrication to deliver significant business value by contributing to improved productivity and reduced costs. In a recent power industry survey commissioned by Shell Lubricants, 58 per cent of companies recognized that lubricant selection can help reduce costs by 5 per cent or more, but fewer than 1 in 10 (8 per cent) realized that the impact of lubrication could be up to six times greater.

At the same time, 60 per cent of companies wouldn’t expect higher quality lubricants to result in a reduction in unplanned downtime. Understanding how lubricants contribute to TCO is the primary step to realising potential savings.

In addition to selecting the right product, effective lubrication management is vital to unlock potential TCO savings. Even the best product cannot perform effectively if it does not reach the right surfaces in the equipment at the right time, in the right amount, without being contaminated or degraded. Effective lubrication management can help deliver value from improved productivity and reductions in lubricant consumption, maintenance and operating costs.

One of the main lubrication management challenges commonly faced by power companies is contamination control. This is critical to maximising the performance of the lubricant in equipment. How the lubricant is stored, handled and transported through the site greatly impacts the likelihood of contamination. Storing drums in a sheltered place and wiping the top clean before it is opened will help limit the risk of contamination by water and particles. Applying filtration can also help ensure product cleanliness before oil enters equipment.

Also important is regular lubricant monitoring and analysis, to ensure the lubricant is functioning well and remains fit for purpose, essentially giving it a regular health check. This can provide early warning of equipment malfunction or wear or lubricant degradation, enabling the lubricant to be changed before issues escalate and thereby helping reduce the frequency, time and cost of maintenance. This also helps improve productivity due to greater equipment availability.

Oil condition monitoring services are available to support customers, by providing early warning of equipment wear or lubricant degradation or other problems. This enables the lubricant to be changed before issues escalate, thereby helping reduce the frequency, time and cost of maintenance. This also helps improve productivity due to greater equipment availability.

Underpinning good lubrication management practices are industry knowledge and expertise. Yet, 59 per cent of power companies surveyed admit they don’t conduct staff training on lubricants as regularly as they should, and only 43 per cent have all the recommended procedures in place to manage and monitor lubricants effectively.

One of the core lubrication management services offered by the team of experts at Shell Lubricants is helping build technical competency across a customer’s organisation.

Case study

One of the largest steel producers in China, Jiangsu Shagang Group (Shagang), experienced problems in its power plant steam turbines just a few months after commissioning the new equipment.

The company discovered that excessive steam ingress to the lubricant system had caused the turbine oil to emulsify and significant amounts of sludge to settle at the bottom of the sump. The excessive contamination had also contributed to accelerated wear of two journal bearings.

Following a review of the turbine lubricant system, oil analysis data and discussions with site management, Shell Lubricants technical experts proposed ways to improve turbine reliability. This included switching to Shell Turbo T 46 turbine oil, adopting the Shell LubeAnalyst oil condition monitoring service, fitting improved seals to prevent steam ingress, and implementing regular draining of water from the bottom of the lubricant tank.

Shell Turbo T 46 turbine oil was recommended for its robust demulsibility control, which means excess water can be easily drained from the steam turbine lubrication system, helping to minimise corrosion and premature wear, and lower the risk of unplanned maintenance. As a result, the company reported annual savings of $57,088.

Modern turbine power plant operators will continue to demand three things from a lubricant: improved system efficiency; reliable equipment protection and longer oil and equipment life.

With pressure on the power industry higher than ever, for many companies the demands of today often supersede the challenges of tomorrow.

For Shell Lubricants, helping customers reduce TCO in the present day is the first step. Equally important is looking ahead to identify the next generation of lubrication products and services that will continue to give companies a competitive edge.

Dr Peter Smith is Shell’s Global Technology Manager for Turbine Oils

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