ENERGY EFFICIENCY GAINS IN MOTOR TECHNOLOGY ASSIST ERWAT
WEG premium efficiency electric motors from Zest WEG are assisting South African water utility ERWAT to respond positively to rising electricity costs at its water treatment plants.
WEG IE3 motors mounted vertically on mixers for downward agitators which are used for ensuring solids entering the anoxic basin/zone do not settle at the bottom. Image credit: Zest WEG
WEG IE3 motors mounted vertically on flash mixers. Image credit: Zest WEG
The roll out of W22 low voltage (LV) motors at ERWAT’s plants will also contribute to improving the general performance of the plants, according to Dillon Govender, sector specialist in public sector business development at company.
“Our WEG W22 motors are constantly improving in terms of their energy efficiency,” says Govender. “Not only have we made our WEG IE3 top premium efficiency motors in this range available to the local market, but now also offer our WEG IE4 super premium efficiency motors at no extra cost.”
Key to ERWAT’s decision to install these motors were the supplier’s local assembly plant and high levels of local inventory which ensure quick and reliable supply. Another factor was the standard five-year warranty provided with the motors. The company also equips the motors to withstand the demanding conditions of operating within the water sector, he says.
“It is important that our W22 motors are readily available ‘off the shelf’ to ERWAT, so there is no delay in delivering the equipment as and when they need it,” he explains. “Our warranty provides peace of mind, giving ERWAT the certainty that these motors will provide maximum uptime for greater plant productivity.”
Govender highlights the value of staying abreast with energy efficiency gains in motor technology as a high proportion of the total cost of ownership is the running cost – which is mainly the cost of electricity.
He notes that the energy savings when using the WEG IE4 super premium efficiency motors reduce their payback times to as little as a year. From this perspective alone, it does not make commercial sense to keep repairing older, less efficient motors.
“In addition to reducing energy consumption, these WEG LV motors also reduce the carbon emissions related to electricity generation in South Africa,” he says. Migrating from the W22 IE3 model to the W22 IE4 is also seamless, as the critical dimensions do not change. The WEG W22 IE4 super premium efficiency motors are designed according to the DIN EN 50347 standard which means they can replace an IE1, IE2 or IE3 motor with similar frame sizes, and as a result no modifications are required when mounting the motors to the base plate.
To operate effectively in a water treatment plant, the motors must also withstand the wet, damp or corrosive environment. This could require solutions ranging from the use of specialised epoxy paint and internal tropicalisation measures, to the supply of canopies for vertical applications.
“Water treatment plants in South Africa also have to contend with the disruption of regular loadshedding, which can reduce their ability to treat the required volumes each day,” says Govender. “This means that these operations can no longer afford unplanned downtime.”
He concludes that the installation of WEG’s W22 LV motors will ensure not only higher energy efficiency but also greater reliability for smoother and trouble-free pumping.
DEWATERING PLAN SAVES THE DAY AT IRON ORE MINE
When flooding at an iron ore mine in South Africa’s Northern Cape province meant it could no longer access the floor of one of its pits, it called in IPR for a sustainable solution.
Rental Development manager at the supplier, previously known as Integrated Pump Rental, Ruaan Venter says the solution began with a dewatering plan. This was vital, as the mine had experienced challenges with groundwater ingress for many years – and these were not being resolved.
“A common open pit dewatering method is to use pumps to extract water from the lowest levels of the mine,” explains Venter. “However, it is often not enough to perform only this step. Rather, the whole groundwater table around the mine has to be lowered, so that the pit is not continually filled with incoming water.”
IPR supplied a large diesel driven pump set to an iron ore mine in the Northern Cape.. Images by IPR
IPR is the Atlas Copco master distributor for its range of dewatering pumps. Images by IPR
He says IPR’s eight years of experience in designing and manufacturing dewatering systems has given it a depth of insight into efficient and reliable groundwater control. The company’s approach is to apply best practice in dewatering applications, and not just send a pump set to site without a good understanding of the operating conditions and the specific challenges being faced.
“In this case, we identified that the primary issue was the application of incorrect dewatering pumps, which were not performing the duty required,” he says. “We implemented a programme to assess and then repair the existing pumps on site – bringing them up to OEM specification so that they would perform reliably and deliver the expected results.”
In line with the dewatering plan, the mine’s own fleet of pumps was supplemented by a custom offering from IPR. This involved some units being purchased outright from the supplier, and other pumps taken on a long-term rental agreement. Venter notes that dewatering has seasonal variations and this could mean that some pumps stand idle for several months during dry periods.
“Our rental programme is offered in recognition of this to relieve customers of the cost of owning equipment that is not optimally utilised,” he says. “Instead, we supply pumps sets that are fully kitted out according to the customer’s requirements – and they are ready for operation.”
He points out that the plan for this mining customer also included an appreciation of water quality and characteristics.
“Groundwater and process water contain abrasive and corrosive elements in varying quantities,” says Venter. “These have an adverse effect on pump performance and life – and need to be built into the pump specifications.”
A key aspect of the plan was therefore to ensure that all pumps performed optimally, to eliminate the risk of repeated flooding. IPR is therefore maintaining all pumps on site, including its own fleet and those belonging to the mine.
“Well-matched solutions help to maximise the longevity and efficiency of the system and also optimise cost-performance ratios,” he says. “We ensure we deliver these results by supplying a complete dewatering package made up of the pump, engine or motor and couplings – as well as auxiliary equipment such as vacuum pumps, control panels and monitors. This service delivers high head pumping where the water levels must remain low for continuous production reliability.”