Find out how new unique gas turbine filtration technology is assisting producers to improve profitability

As the offshore oil and gas industry deals with a sudden and deep drop in oil prices triggered by the COVID-19 pandemic and subsequent Russia-Saudi Arabia price war, producers must find new ways to recoup their margins.

Thanks to a decade of oil price fluctuations and the ever-growing pressure to decarbonise, the offshore industry has become hard-wired to effective change management. Yet, despite this, the recent plunge in energy demand and oil prices has left even the most seasoned executives wondering how best to protect their businesses.

What we do know is that producers must find new ways to recoup their margins. If operational savings are instigated, those responsible must then decide how best to allocate the scarce budget that remains in a way that protects the long-term success of their assets and business, while also guaranteeing sustainability and energy security.

In very basic terms, the production of offshore oil and gas cannot be delivered without gas turbines, which run both the mechanical drive and power generation applications on offshore platforms. Indeed, most would agree that gas turbines are a critical business function, and this is reflected in the industry’s long-term focus on turbine reliability and availability. The rationale being, that an asset performing well in these key areas brings greater prospects of overall efficiency, sustainability and profitability. 

Traditional approaches

Gas turbine maintenance has long focused on the importance of maintaining the engine components rather than the ancillary equipment. A critical example that often escapes attention is the fundamental importance of air filtration systems, which have the ability to protect gas turbines from the harsh offshore environment, while promoting better compressor cleanliness and long-term part integrity.

Currently, around 85% of offshore gas turbines are protected by small high velocity filtration systems that utilise low efficiency filter bags, which only provide protection against coarse particles, and fail to capture sub-micron particles offshore. It is worth noting that the air quality at platform level is significantly different to sea level, at the height of an offshore platform the majority of particles in the air are sub-micron in size. The vast majority of particles of this size will pass straight through the low efficiency filter bags. This can lead to unplanned gas turbine shutdowns and costly downtime, reduced component and engine life, premature engine failure, and low turbine compression efficiency as well as high CO2 emissions. 

All of these impacts are significantly magnified and unwanted given today’s current market dynamics and the low price of oil. What’s more, high velocity systems are designed to allow water, moisture or fog to coalesce as it passes through the filter bags. This process creates larger droplets which are designed to be captured by a downstream vane after the filter bags. However, vanes are not 100% efficient and some of the water and salt in solution will pass through the vanes. In addition, water will often collect on the floor downstream of the bags and upstream of the final vanes.  The salt laden water will evaporate over time, which will allow salt crystals to enter the airstream and hence a proportion of these dry salt crystals will pass through the vanes into the gas turbine.

Seizing a unique opportunity for change

Low efficiency filter bags only capture around 5% of sub-micron particles (particle size to calculate this data was 0.3 micron). By contrast, high Efficiency Particulate Air Filter (EPA) E12 technology captures 99.95% of particles at this size. This significantly protects expensive gas turbine components and removes the need for frequent water washing to clean the engine.

As offshore operators have become aware of the benefits of EPA E12 air intake filtration, there has been a push to upgrade existing high velocity units installed offshore. However, traditional EPA E12 filtration technologies - with much larger equipment envelopes - have necessitated that the air intake housing is replaced in its entirety.  This increases foundation loads and incurs significant costs and downtime. However, there is another route, using a new revolutionary EPA E12 system which provides all the associated benefits of EPA E12 air filtration, but can be quickly and seamlessly installed within the existing high velocity air intake filtration system.

AAF’s N-hance filtration technology is an EPA E12 technology for offshore high velocity applications, asset owners and managers can build further resilience into their gas turbines and rigs, increasing energy security through a reduction in unplanned downtime and shortening shutdown periods, all while significantly reducing the risk of catastrophic failure. Notwithstanding short-term cashflow issues, such proven technology is part of the solution to a secure long-term future for the offshore oil and gas industry.

BP Clair

BP’s Clair platform in the North Sea, demonstrates the optimum role air filtration systems can play in unlocking considerable financial, operational and environmental benefits.

In 2017, BP was aware that AAF International was in the final stages of developing a new EPA E12 high velocity filtration solution. Critically this new design could be installed within an existing high velocity housing with no penalty in differential pressure (dP), therefore negating the need for a larger replacement filter housing. BP was expediting the GT OEM (Original Equipment Manufacturer) for fast-track delivery of a replacement engine after poor filtration provided by the high velocity bag system resulted in a catastrophic failure of one of the platforms gas turbines after 12,000 operating hours, which equated to only a 1/3 of the engine design life.

AAF’s N-hance EPA E12 filters and conversion parts were delivered to BP within 5 weeks and commissioned along with the new engine on BP Clair in February 2017. There was a significant increase in engine availability resulting from a reduction in unplanned downtime and a significant reduction in water washing. There was also a decrease in CO2 emissions improving sustainability, as well as retained power output (compressor efficiency) and heat rate. 

Commenting on the project, BP’s asset team said: “The upgrade project has enabled improved reliability, cost savings and will feed into the reformation of outdated air filtration standards as well as playing a part in helping to achieve offshore asset efficiency of 90%.”

Read the latest issue of the OGV Energy magazine HERE.