Daniel Gontermann

KSB Drives and Mechatronic Solutions
www.ksb.com

KSB has always focused primarily on optimisation of pumps. The sheer number of different pump casings, materials and impeller adjustment options available confirms this. However, conditions can change during the pumps life, it often no longer runs at the optimum operating point. For years, KSB experts have been investigating ways to optimise pumps more easily without using complex analytics or having to replace the pump.

Digitalisation offers tremendous potential for this, however, it takes time to develop. “It requires transferring decades of experience and expertise into an algorithm and a software solution,” explains Dr Thomas Paulus, Head of Programme Office Digitalisation & Startup Projects at KSB. “This cannot be done in a single step: it involves many different components and aspects. By bringing these component parts together, you end up with an intelligent and practical concept that provides real added value for the pump operator.”

Step 1 – The Digital Monitoring Unit

The KSB “PumpMeter” monitoring unit shows in plain language what goes on inside a pump. With pressure sensors and an analysing display unit fitted to the pump, suction and discharge pressures are measured around the clock. The PumpMeter uses this data to calculate the differential pressure and determines the current operating point, updated in real time.

A typical four-quadrant pump characteristic curve shows the pump operating range at a point in time. This display allows the operator to evaluate the operating point upon start-up and adjust the pump accordingly. Operators see at a glance whether the availability of their pumps is at risk and whether they are operating economically or if there is potential for significant energy savings.

Step 2 – Algorithms to Interpret Vibration Characteristics

In the future, instead of using wetted sensors, it will be possible to record vibrations and transfer this data to the cloud using mobile communication. This has two advantages:

Conventional measurements are not always straightforward, particularly when pumped medium is a chemical product.

With cloud access, technicians can obtain information about the pump status anywhere in the world without being on site.

This application is currently being piloted successfully with 100 selected partners. Measurements taken in parallel using PumpMeter are being used to verify the values from vibration sensors, while the KSB team is continuing to optimise the underlying algorithms. According to Dr Paulus: “From these results, it is already easy to see whether it makes sense to switch to closed-loop control, change operation modes, or replace the pump.” The data is transferred to the cloud via a portal. KSB processes the data, the user receives an automatically generated PDF with clear recommendations and improvement suggestions for the pump.

Step 3 – Operating Point Optimisation with MyFlow

How can these improvement suggestions be actioned? What if it were possible to adjust the pump using software instead of adjusting the impeller manually?

“This is possible with our MyFlow Technology,” says Daniel Gontermann, Head of Product Management – Drives and Mechatronic Solutions at KSB. With a combination of the KSB SuPremE IE5 motor and MyFlow Drive, the conventional approach for fixed speed pumps of trimming the impeller to match the operating point gives way to adjustment by changing the speed.

MyFlow Technology offers many advantages in day-to-day work. Because the operating voltage of the IE5 synchronous reluctance motor is modulated by the minimum frequency inverter mounted on the motor, it can be used in almost any power grid around the world, global engineering contractors no longer need to consider the local mains voltage when selecting pumps. Direction of rotation is now defined at the factory, saving time and costs of conventional direction-of-rotation checks.

Step 4 – Software-Controlled Pump Adjustment

“Although these advantages make the pump operator’s job much easier, they are not enough to make a pump fit for Industry 4.0,” acknowledges Daniel Gontermann. “Nevertheless, they form the basis for the next crucial step: pump optimisation using virtual impeller trimming.”

During it’s life cycle, the pump speed can be adjusted to individual requirements – pump optimisation with virtual impeller trimming, fast and convenient by smartphone or tablet. “A software application is used to bring the pump closer to its optimum operating point,” says the pump specialist. No interruption of operating process, quick, economical energy efficiency optimization if the Q/H point deviates from design values, reaction to system-induced operating point changes. “Because speed change brings power change, substantial savings can be made”

“During development, attention was paid to security. The KSB FlowManager app establishes point-to-point connection, ensuring the correct pump is addressed, only by the authorized person” says Daniel Gontermann.

“The great thing is, you can now defer the individualisation of the pump to a much later point in the supply chain.” Another aspect likely to play a role in future pump selection is, with individual fixed speed adjustment, fewer pump sizes now cover the entire selection chart – efficiency and NPSH values remaining practically constant. Variant complexity for hydraulics is reduced by more than 50%, saving time and money on design and administration. “Simply reducing complexity with fewer variants will promote virtual impeller trimming,” continues Daniel Gontermann.

Outlook

Original equipment manufacturers (OEMs) will benefit from the new opportunities presented by digitalisation, being able to drastically reduce their stock, for example. While this shows the direction in which pump technology will move, “Digitalisation is not an end in itself,” emphasises Dr Paulus. “Users will only accept new technologies if they bring added value to their day-to-day work and are workable.” This is one of the greatest challenges. It is useful that KSB set out on the road to digital future early. “In the way we have been getting the most from pumps in performance and efficiency for decades, we are now also making progress developing algorithms and software. Without our many years of pump expertise, it would be impossible to make a pump fit for the Industry 4.0 era.”

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Keith Hutchings

Senior Market Development Engineer
Hydro International
hydro-int.com

It should not come as a surprise to wastewater treatment plant operators that grit is a problem. What might come as a surprise, however, is how much grit can cost a plant.

If nuisance inorganic solids are not removed early on then they will pass through the plant, causing abrasion damage in equipment such as pumps, bearings and conveyance systems and accumulating in essential treatment systems such as settling tanks, channels and digesters.

This damage and clogging reduces the plant’s operating efficiency, increases energy use, shortens equipment lifetimes and increases both the cost and the frequency of essential cleaning and maintenance.

Challenging the convention of grit removal

A fundamental problem is that many conventional grit removal technologies have been designed to capture solids that simply don’t reflect the nature of grit that plants encounter in the real world.

The latest issue of the UK WIMES specification for grit removal persists with the expectation that 95% of all grit is larger than 212 μm with a specific gravity of greater than 2.65—equivalent to silica sand. Although the guidance notes do now show a nod to the existence of finer material, this will only ever be discovered through obtaining a representative particle size distribution (PSD).

It has been recognised for some time wastewater grit contains solid particles of various composition—from silica sand to particles of concrete, limestone and even bone—that can be as small as 50 μm in size, with irregular shapes that can be made more buoyant by attached materials such as fats, oils and greases (FOG). In fact, treatment plants in the United States have reported that over 50% of their influent grit settles as if it is a particle smaller than 212 μm (Osei & Andoh, 2008).

Smaller solids and larger particles with attached FOG such as these tend to pass through conventional grit removal technologies and accumulate in downstream areas of the wastewater treatment plant.

Fortunately for operators, however, these outdated design specifications are being challenged—Wilson (2007), McNamara et al (2009) and Judd et al (2017) have argued that real-world wastewater grit particles settle at much slower velocities than those relating to the smooth, dry silica sand on which the design specifications were based—so we are hopeful that a more pragmatic approach based on tackling real-world wastewater grit be adopted.

Plan for better grit removal

Therefore, if we are to abandon the artificial assumption that wastewater grit is all spherical silica sand and instead think of grit as a complex solid with variable shape and composition, then we must also abandon the assumption that removing 212 μm diameter grit will suffice for any treatment plant.

In the same way that grit is a variable factor, so is the plant and its requirements. A plant’s grit removal performance should be reviewed in the context of the plant as a whole, including investments that target seemingly unrelated treatment systems. Investment in a digester, for example, should take into account grit removal, as the digester’s performance—and therefore cost of operation and maintenance—will increase if inorganic solids are allowed to accumulate and clog it.

With this in mind, it is clear that grit removal should be considered early on in the planning and design phases of any wastewater treatment plant build or upgrade project, and that the performance of the grit removal system should be tailored not only to the composition of the local influent grit, but also to the downstream processes that it is designed to protect. A recent study and subsequent guidelines issued by the Water Environment Federation (WEF) acknowledges the increased emphasis on finer grit removal with the advances in tertiary and solids treatment

Get advanced

Fortunately, technologies are available that take into account the nature and characteristics of the kinds of grit that wastewater treatment plants encounter in the real world.

Targeting >95% removal of inorganic solids with a minimum diameter of between 75 μm and 150 μm, technologies such as HeadCell® and Grit King® provide a high level of protection for plants that want to make savings on their operating and maintenance budgets.

Hydro International wastewater experts have also developed a free eGuide for operators, outlining the approach and steps required to implement the kind of effective grit removal necessary to cut the cost of grit.

Taking an Advanced Grit Management® approach to grit removal equips treatment plant operators with a set of effective tools and techniques that will help them to start identifying savings on existing plants, and building savings into upgrades future plants.

Conclusion

Wastewater grit is a costly menace to treatment plants, and its impacts have been built into many plants thanks to outdated, artificial assumptions and design specification that don’t sufficiently reflect the reality of wastewater grit. Forward-looking experts and treatment plant operators are challenging those assumptions, however, and are finally moving the industry away from this costly model and towards a grit removal approach that is designed to solve real-world problems.

New technologies are available to target the damaging finer grit that conventional removal systems typically miss, and new approaches to grit removal—such as the Advanced Grit Management® philosophy—provide operators with new ways to tackle inorganic solids and reduce the hidden costs of grit.

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