Making the right choice of process filtration supplier has never been more important given the operational and financial pressures facing today’s oil and gas industry. Producers and their service providers need to find optimal solutions that guarantee a cost-effective use of operating expenditure over a robust, longlasting service life. A knowledgeable supplier that specialises in both the design and manufacture of filters and housings is best placed to deliver on customer specifications. UK specialist Amazon Filters has been working with a growing list of oil and gas customers this year, supporting them through all stages of production. For its most recent industry order, the company has supplied and fitted hundreds of HFCs (high flow cartridges) on a deepsea FPSO.

 

Operational Challenges

Process engineers at the platform had concerns over the performance of membrane pre-filtration on their onboard SRP (sulphate reduction plant). Filter cartridge change-outs were being done every two to three days, and each housing was taking 24 hours to execute a change of cartridges.

Aside from the vast consumables cost, the operational challenges posed by such frequent and lengthy cartridge replacements were significant. Further investigation revealed a number of serious issues.

The filter housings were undersized for the task in hand, due almost certainly to an earlier decision to focus on capital rather than lifetime costs. The upshot was a very high flux rate for seawater service which is guaranteed to lead to shorter filter life.

The filter internal assemblies did not adequately support the cartridges as they should have done. This was limiting the maximum differential pressure at which the cartridges could be operated even at time of relatively low pressure drops. It was well below their intended dirty values, resulting in the full dirt holding capacity of the cartridges not being utilised. Due to inadequate internals design, some cartridges would inevitably rupture which necessitated disassembly and manual cleaning out of the broken debris on each change-out.

 

Robust Replacements

The Amazon Filters solution was to supply replacement internal assemblies with metal screen supports that could be bolted in, operate to a higher differential pressure over a longer lifetime and offer greater dirt-holding capacity than the originals.

As well as supporting the cartridges properly, the number fitted was increased through better arrangement in the available space, resulting in a 20% increase in filtration area.

This has the benefit of reducing the pressure drop and flux rate through each filter which in turn increases service life. Delivered ahead of schedule, the replacement internals were fitted by the customer with no modifications to the filter vessels required.

The improvements were dramatic. Cartridge change-out frequency was reduced from two-to-three days to two weeks, with change-out time itself cut from 24 hours to five hours.

Alongside the use of Amazon Filters filter cartridges at a cheaper unit price than the original fitted ones, the solution delivered a 90% reduction in spend on cartridges, paying back the capital investment in under a month. At the same time, maintenance hours were reduced as far as possible given the constraints of the poorly designed original housings.

 

Focus on the Long Term

Commenting on the successful outcome, Amazon Filters’ Project Specialist Padrig O’Hara said: “The headline message for oil and gas producers concerned with cost control right now is to look at the total lifetime costs of their filtration solutions and not to fixate on initial capital costs. In this application simply retrofitting an equivalent filter product would not have solved the problem. You need to work with a supplier that has a proven track record in understanding the application and designing bespoke solutions. We concentrate on adding value, not just retrofitting. In this particular instance, our approach has given our FPSO customer a huge saving in the number of cartridges used annually. That’s on top of all the other complementary benefits of reduced maintenance time and consistent protection of the SRP membrane.”

 

Tackling Contamination

As well as offering bespoke solutions, Amazon Filters has been busy with product development, launching its latest innovation in meltblown depth filter cartridges in summer 2021. Contour Gas is designed to stop black powder contamination accumulating in upstream pipework and harming downstream equipment and instrumentation. Black powder is mainly composed of fine but hard particles of iron oxide (Fe2O3) and iron sulfide (FeS) in sizes from 100µm down to sub-micron level. Typically caused by corrosion and erosion, these particles are swept along pipework at high speed in the gas flow. Once they reach downstream infrastructure, they can easily cause costly downtime and endanger production safety.

Ideal for high-flow, large-diameter applications, Contour Gas cartridges are made in a tightly controlled manufacturing process supported by environmental quality systems. It involves highstrength fibres being blown continuously onto a central mandrel, building into a one-piece, corefree construction resistant to unloading and media shedding. Ahead of launch, efficiency was tested in line with the requirements of major oil and gas companies using specific challenge levels appropriate to real-life installations.

Karl Pizzey, Amazon Filters’ Operations Director, said: “Contour Gas provides reliable and consistent filtration of the dirt particles in gases, with the flexibility to capture sizes from 0.3µm to 100µm and above. It is available in fine and coarse-graded density structures to match process requirements, the degree of distribution of the black powder, and the subsurface elements and compounds that are causing the contamination. We have engineered Contour Gas as a high-volume filtration solution for offshore natural gas pipelines, other gas-carrying transmission lines, supply tanks and gas processing plants - all essential areas where long service life and ease and speed of change-out is crucial. Contour Gas offers wide chemical compatibility with a choice of 100% polypropylene and nylon versions, double open-ended formats and two standard element sizes, 508mm (20”) and 1013mm (40”). Its flexibility means it can be used for new installations or as a direct retrofit for either core or coreless filters on existing housing designs affected by black powder.”

 

Coalescer Technology

The launch of Contour Gas followed the release earlier in the year of SupaSep LGP, the latest evolution of Amazon Filters’ liquid-gas coalescers, used extensively in upstream, midstream and downstream operations. The new filters can be supplied complete in a bespoke housing or as direct retrofits for products such as Pall Seprasol or Parker Peco DynaCeptor.

HIGH PERFORMANCE: The SupaSep LGP coalescer harnesses highly effective filtration media made of glass microfibre with a drainage layer of polypropylene or polyester.
The inner core is stainless steel and the heat-bonded end caps are polypropylene or nylon.

 

SupaSep LGP incorporates a patented process for both interpleat and meltblown drainage configurations and to combat re-entrainment of fluids in the housing outlet through a robust barrier. This is designed to support the efficiency and drainage performance of highflow filtration and separation processes while protecting essential assets such as gas turbines, natural gas compressors, lube oil recovery equipment and catalyst beds. SupaSep LGP also supports the recovery of fluids involved in the sweetening and dehydration of natural gas.

Among the product’s key strengths is the ability to vary filtration efficiency throughout the filter depth and confer additional properties such as oleophilicity and hydrophobicity.