Electric submersible reduces maintenance, lowers costs, and eliminates pollution concerns
ENERGY savings of around US$1,000 per month are one of several benefits for the new owners of a southern Wisconsin aggregate plant who made the decision to replace existing diesel-powered dewatering equipment with a high-volume electric submersible GSZ pump from Tsurumi.
Being at risk of quickly filling up with water and because electric submersibles are commonly – and mistakenly – assumed to be useful only in small pits, the quarry had long been seen as a typical application for diesel pumps.
But with the diesel-powered pumps releasing harmful emissions and costing about US$1,600 in fuel per unit per month to operate, the quarry’s new owners decided improvements had to be made and called on ‘pump guy’ Brian Radovich, vice-president of Tsurumi distributor Wisconsin Shoring & Supply and an expert in groundwater pumps, for advice.
‘GSZ pumps are the most formidable high-volume dewatering pumps offered today,’ explained Mr Radovich, ‘so, with the help of Tsurumi Midwest regional manager Joe Ranieri, I recommended the GSZ5-37-4H unit for the quarry.’
Despite standing just over 61in tall, and being approximately 35in in diameter, the newly installed electric submersible pump is one of the smallest and lowest-horsepower units in the GSZ range but has proven more than capable of emptying the Wisconsin quarry void. With its 50hp output (the range tops out at 200hp) and 6in-diameter discharge, it efficiently pumps the water 100ft up to a retention pond for use as process water in the wash plants.
‘Now that they have switched to our electric pump, the running costs are only US$600 a month, a saving of around US$12,000 a year,’ said Mr Ranieri. ‘But, in addition to those cost savings, there is a huge increase in the level of equipment availability, given the amount of downtime that typically comes with diesel pumps due to their more intensive servicing requirement.'
The GSZ pump can typically double or even triple parts wear life in aggressive dewatering applications due to an impeller speed that is 50% lower than alternatives. It also boasts excellent durability due to its high chrome impeller, cast iron suction cover, and stainless-steel fasteners.
Moreover, in contrast with the high level of maintenance required by the oil-filled seals of diesel pumps, Tsurumi’s four-pole, 1,800 rev/min models feature exclusive seal pressure-relief ports that protect their mechanical seals by providing a flow path above the pump casing to allow a release of water from the pump and away from the shaft.
The mechanical seals remain isolated in the oil chamber above this flow path, protected from any excessive pumping pressure or water hammer that may cause premature wear or failure of the mechanical seals in high-pressure applications.
‘Any pump with vacuum prime can suffer volume loss on the suction,’ continued Mr Ranieri. ‘The diesel pumps used previously would burn through oil quite quickly, so the guys had to keep filling them up. Then, over the course of six to 12 months, they’d have to pull the whole pump apart and replace the oil seal, and there was always the possibility of contaminating the groundwater in the event of a diesel or oil leak, so the customer was obviously very happy to avoid that.’
As well as eliminating oil changes, further savings have been made by eliminating the need to refuel the pump every two or three days.
At the Wisconsin site, a small, lightweight, KTV series pump also plays a vital and innovative role in ensuring the GSZ operates flawlessly throughout the bitterly cold Midwest winter, when freezing water could result in damage to the pump or its hose, or lead to other issues. The KTV creates a constant turbulence that prevents the water around the GSZ from freezing.
‘Brian came up with the idea of running a 1hp KTV2-8 pump in the pit without a hose on the discharge, so it works as a fountain that keeps the water in motion,’ said Mr Ranieri. ‘Even during Wisconsin’s coldest winter nights, it ensures a decent-sized area of water remains in liquid state to prevent any problems arising.’
Despite being designed for light-to-medium-duty applications, the wear-resistant KTV pump has easily handled the demands placed on it, ensuring the GSZ pump continues to function as expected.
‘The installation has been in place for more than a year now and it’s worked out great, even over what was an extremely cold winter in 2021,’ concluded Mr Radovich. ‘It might be the quarry’s first GSZ pump, but I doubt it will be the last one we install in applications like this.’