The relationship between pump system efficiency and effective use of energy is well documented but present circumstances have accentuated its importance, together with some dangers.
Energy crises tend to come with a long tail of secondary problems in their wake. The present one is no different except that, given the complexity and scale of today’s global supply chains, it may be more pronounced than some of its predecessors.
To take one very recent example of the consequence effect, rising energy costs have hit the glassware industry hard because the process of making products remains highly energy intensive. As a result, prices have risen around 80 per cent for the manufacturers of bottled beers, with smaller batch-producing craft brewers worst hit.
It’s an often-repeated mantra (not least in these pages) that pumps systems play a disproportionate role in a company or plant’s energy expenditure. They tend to account for the largest proportion of energy usage – around 40 per cent – but they also offer the greatest leverage when it comes to reducing energy costs.
Again, it’s been an oft-repeated fact that, while pump energy efficiency varies greatly from one operation to another overall, industry has tremendous potential for significant savings thanks to the deficiencies of so much equipment and the way in which it is operated.
Of course, there is a proportion of pumps that are simply at the end of their life cycle but often the problems are subtler; assets that do not harness the latest technological innovations, or those which operate outside their best efficiency point (BEP) and either underperform or provide too much power and expend energy needlessly.
US manufacturer ITT is among many manufacturers seeking to extend the use of smart systems in place of more fallible human, manual solutions. Given that an estimated half of all pumps operate outside their desired range, the benefits are obvious.
Said a spokesperson: “For pump users, controlling the amount of energy being consumed by the pump is an ongoing concern. To combat the issue, variable flow/frequency drives (VFDs) are gaining traction, allowing engineers to customise the amount of work done by a motor and pump to the actual load.”
The firm’s award-winning PumpSmart drive offers real-time control to reduce energy consumption, with the added bonus of reducing wear, tear and repairs and thereby extending equipment life. There’s also of course the all-important consideration of environmental benefit.
“VFDs are an easy way to customise the amount of work done by a motor and pump to the actual load. The pump control logic of the PumpSmart drive delivers real-time control and protection of your pumps to reduce energy consumption. Smart pump protection algorithms reduce wear and tear on process systems to extend equipment lifetimes and reduce un-planned repairs by protecting against process upsets,” says the company.
While the efficiency benefits will vary by a wide margin of 30-80 per cent, admits ITT, depending upon the performance of the original assets used, the company estimates its drives saved approximately 34,000 metric tons of CO2 emissions last year, equivalent to 4,000-plus homes’ energy usage or recycling 11,647 tons of waste.
However, automation and smart technology in particular can be something of a double-edged sword, thanks to the wider context in which pumps and the energy sector must operate.
The most recent contributor to the global energy crisis – Russia’s aggression against Ukraine – is a reminder that utilities and their related systems are now seen as targets for hostile state actors and criminal hackers. And the extension of such activities to critical infrastructure is a direct if unintended and undesired result of industrial automation and digitalisation.
Risk management consultancy DNV’s recent The Cyber Priority report, which included a comprehensive survey of nearly 1,000 energy leaders worldwide, laid bare the possibility of operational technology being used as a Trojan horse for cyberattacks.
Explained DNV managing director, cyber security, Trond Solberg [pictured]: “Energy companies have been tackling IT security for several decades. However, securing operational technology – the computing and communica- tions systems that manage, monitor and control industrial operations – is a more recent and increasingly urgent challenge for the sector.
“As OT becomes more networked and connected to IT systems, attackers can access and control systems operating critical infrastructure such as power grids, wind farms, pipelines and refineries... the energy industry is waking up to the OT security threat, but swifter action must be taken to combat it.”
That however remains a caveat to be addressed when extending pump system performance and efficiency, not an argument against adoption of more sophisticated operating methods.
As Sulzer business development manager control and monitoring Jo?rgen Ja?ger explains, control technology enables smarter and more pro-active management through interconnectivity. And the good news for those contemplating upgrades but concerned about costs is that smart controllers do not entail “a mass of costly new hardware”.
Using the example of smart controls introduced for one UK pumping station, he explains: “Whatever technology is used, built-in features of the Sulzer controllers can monitor sensor performance and alert operators if a sensor becomes faulty or poorly calibrated.
“The system can also warn of other problems in the station. That allows operators to deploy field maintenance resources quickly and cost-effectively.”
The result, he said, was a 45 per cent reduction in operating costs and a drop of three quarters in potential environmental impact cost.
The system can also warn of other problems in the station. That allows operators to deploy field maintenance resources quickly and cost-effectively
Jo?rgen Ja?ger, business development manager control & monitoring, Sulzer
While smart tech is crucial to protecting commercial margins, so too is materials science, says Sulzer, when seeking to minimise energy consumption. Its work over more than a decade with Europe’s largest reverse-osmosis site, the Torrevieja desalination plant in Spain, has depended upon the corrosion resistant quality of its high-pressure pumps that must combat the challenges of handling vast quantities of sea water and produce more than 14 million cubic meters of fresh water per day.
Connectivity of the non-digital variety is also a feature when more mundane process problems arise. Pumps specialist Landia worked with Viridian Systems to install a new mixer for a landfill’s leachate treatment centre plagued by floating biomass.
Not only did this cut sludge settling time by 75 per cent, it created a sav-ing of nearly £0.3 million from leachate that no longer needed transportation off site as well as an estimated £85,000 saving on chemicals.
Less foam not only brought further savings but also improved the efficiency of the plant’s dissolved oxygen probe, provided better control of blower speed and vitally reduced energy consumption. And that also off-set the mixer’s power consumption.
Viridian MD Roger Dixon comments: “We believed that with the correct type of mixer; suitably positioned, powered and timed, the right amount of agitation would disperse the floating layer to allow solids to settle much more quickly. What has been achieved provides considerable on-going benefits for our customer.”
Given that the situation regarding energy supply and cost is one of the worst in recent decades, solutions at the macro level will be a long time in coming. In what could prove to be a lengthy interlude, the efforts made by individual businesses to trim their costs will be crucial, if incremental.
That ultimately means innovating to create greater efficiencies. And, in the main, that means monitoring those pumping systems as these represent consistently the greatest cause of one’s energy usage.
BEP’s the way forward
A well run pump system needs optimised performance, says Griswold product manager James Farley. For that you need to achieve its best efficiency point.
Best efficiency point (BEP) is the target operating range for a pump – its sweet spot on the performance curve, a combination where flow and head rates are at ideal produc- tivity. Operators can calculate and anticipate where a pump will function most efficiently using a formula or the performance curve.
To illustrate the BEP for target pump operation, calculate pump efficiency based on head, flow, specific gravity and horsepower. It’s helpful to confirm this optimal efficiency point visually on an evaluation (or perfor- mance) curve graph.
Testing pump performance in a lab setting best represents this difference in efficiencies.
When you increase flow rate, gallons per minute rise, but head decreases, with a higher horsepower consuming more energy but not yielding better performance.
In this case, efficiency will drop below BEP, falling to the right of the performance curve.
Decreasing the pump’s flow rate below the BEP reduces gallons per minute and causes head pressure to go up and power consumption to go down, again operating below efficiency.
Pump efficiency dramatically changes when you alter different factors of operation such as flow rate. Naturally, this affects system performance and productivity.
By calculating and operating at the best efficiency point for your specific pump and application, you can optimise system performance.
