Thus rotating equipment in direct contact with the process media presents a challenge. However, he points out, one can reduce degradation by selecting the correct protective coating.
“In the harshest of operating conditions, solid and/or liquid particles can pass through the equipment causing erosion. This can result in moderate to severe material loss and change aerodynamic efficiencies significantly. If left unattended, it can even affect the strength of the critical components and lead to premature blade/vane wear and failure in service.”
Specialised coatings give effective protection against fouling and erosion, with their composition tailored to specific applications and including an aluminum base coat for corrosion protection plus inorganic sealer and a specialist non-stick final layer.
In the case of chemical manufacturing processes such as fertiliser production, rotating equipment maintenance is vital, with the emphasis on prevention rather than remedy, he cautions.
“Using a preventative maintenance approach to uphold the reliability and efficiency of equipment is an important strategy. In addition to this, retrofit projects enable new materials and component designs to be integrated with legacy equipment, extending their service life and reducing operating costs.”
Within plants and factories dependent upon large numbers of pumps, remanufacturing of impellers, balancing and bearing overhauls can be contained within scheduled maintenance intervals, with surface treatments applied to extend operational life, explains Sulzer Middlesbrough service centre manager Paul Richardson.
“At the centre of a pump’s design is the impeller, which provides an increase in the fluid head. As a result, impellers are subjected to the most damage, which can have a huge impact on efficiency, productivity and running costs. “Therefore, it is important to be able to source new impellers when they are required and, if necessary, take advantage of the latest improve- ments in design and materials technology to increase reliability.”
Creating replacement parts has become a much quicker process. The use of reverse engineering to design and manufacture enhanced components has rendered replacement a much speedier process. Improved flow geometry and manufacturing techniques including 5-axis milling or rapid prototyping techniques to print casting molds have led to significant performance and reliability gains.
Nevertheless, there are situations where retrofit and preventative maintenance are insufficient, advises Geoff VanLeeuwen, product management director for Blackmer.
Chemical pump technology is in demand beyond its key market thanks to the ability of products to tackle corrosion and other challenges. Often, though, the focus in pump purchasing generally is too greatly centred on price tag.
Says VanLeeuwen: “Facility managers who rely on industrial pumps for the various liquid-transfer duties in their manu- facturing processes can be excused if they occasionally think that once the pump has been purchased the majority of the heavy lifting has been completed.
“Identifying the right pump for the right process requires a lot of time and due diligence, from performance reviews to cost estimates, to even soliciting opinions from other manufacturers.” Studies suggest, he says, that pump purchase price comprises a mere 10% to 15% of total life-cycle cost. In fact it is one of five elements that ought to inform purchase decisions, he advises. These encompass capital, installation, operation, maintenance and decommissioning costs.
In chemical manufacturing industry, centrifugal pumps are often the default liquid transfer technology, states VanLeeuwen. This can have drawbacks when choosing purchases.
“The problem with this mindset is that it means that many chemical-processing systems have been designed around the needs of the pump, rather than the needs of the system. For example, design engineers will design their systems so that raw materials can be blended or heated in a way that their viscosity is brought to a level that enables them to be handled by a centrifugal pump,” he explains.
“In this case, they are reconditioning the material to fit the need of the pump, regardless of any potential life-cycle cost impact.”
The operator, in addition to getting the viscosity to a centrifugal- friendly level, must also ensure that the pump continues to operate at its Best Efficiency Point (BEP). Operating outside the BEP can result in shaft deflection that will place higher loads on the pump’s bearings and mechanical seal, which can damage the pump’s casing, impeller and back plate. This leads to higher maintenance and part-replacement, coupled with the costs required to keep the pump operating at its BEP that combine to increase total life-cycle costs.
Key considerations for installation are: additional costs for boring – a factor that adds to the price tag for cheaper to purchase vertical pumps; alignment issues; and any commissioning price.
The issue of operational costs highlights different approaches to sizing for PD and centrifugal pump motors, he adds. The former is sized according to bypass value set point, limiting energy consumed; the latter tends towards oversizing.
Many chemical-processing systems have been designed around the needs of the pump, rather than the needs of the system
Geoff VanLeeuwen, product management directo, Blackmer
There is also the matter of ancillary liquids employed, warns VanLeeuwen. Sealed pumps requiring a quench can substantially increase annual water costs if used at scale, for example.
Maintenance is to a significant extent dependent upon the number of ‘wear’ parts a particular pump possesses. However modern technologies have increased the effectiveness of remote and accurate predictive maintenance.
Finally, often excluded from life cost assessments, pump decommissioning or disposal, while rarely prohibitive are likely to be higher in sectors such as chemicals “if the pump has been used in the handling of hazardous, toxic, radioactive or any other materials that require environmental sensitivity”.
While these factors may vary in influence, the development of advanced remote pump-monitoring technologies promises to be a boon in optimising pump life-cycle costs, suggests VanLeeuwen, permitting the identification of operational inefficiencies sooner and more reliably, creating real-time operational transparency and significant cost savings for the operator.
Likewise, he says, remote Cloud-based pump-monitoring systems create opportunities to gather pump-performance data and store it for future use.
“The challenge is finding the best ways to use this data to observe and predict pump performance, with the goal of optimising it as it pertains to total life-cycle cost.”