Pumping
Machinery, LLC
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Fabricated Impellers Save Time and Money
When time or cost are not a big consideration, traditionally pump impellers are produced by casting method. However, as designs get old, pump manufacturers merge or go out of service, it is becoming increasingly difficult for an end user to get a replacement impeller quickly and economically. Pumping Machinery company provides the end users with an alternative – to save time and money. There are three reasons why our fabricated impellers are popular:
a. Emergency replacement of the hard-to-find designs b. Efficiency improvement c. Design change to “shift” Best Efficiency Flow (BEP mod)
We can do it for any type of pump, for example:
End-suction Double-Suction Split Case Vertical Turbine Multi-Stage
a. Emergency replacement of the hard-to-find designs – example:
Municipal wastewater lift station experienced catastrophic failure of the pump impeller. This vintage 1940 pump design would have needed 6 weeks and added cost to produce new mold pattern to replace the worn-out old pattern, and another 8 weeks to produce an expensive casting from the new mold pattern. With only one pump remaining in service, operating personnel could not wait that long to risk potential station flooding. Pumping Machinery was asked to assist. The pump was pulled and repaired, with the impeller fabricated over the weekend, at approximately half of the cost of the new impeller, and no need for a mold pattern:
From old impeller - to fabricated new – in one week and half cost
b. Efficiency improvement
With age, pump efficiency deteriorates. To estimate what a pump efficiency should be, Hydraulic Institute has published guides. Our web site has a handy and simple program to help you estimate the expected efficiency of your pump. We can also help you field measure the actual efficiency of your pump to compare: www.mj-integratedsolutions.com/pump_tools/pump_efficiency.htm
Our replacement impeller will restore your pump efficiency and save money. Even for a small pump with performance shown above, energy savings add up, but consider for example a bigger (say 1,000 hp unit), which runs continuously, 24 hours a day, 360 days a year. At an estimated energy cost of $0.10 per kw-hr, these 1000 hp (746 kW), will consume 746 x 24 x 360 x 0.10 = $644,544 per year. Even if only 10% of the pump deteriorated efficiency is restored, the energy cost would be nearly $65,000 per year!
c. Design change to “shift” Best Efficiency Flow (BEP mod)
Even more powerful is a so-called BEP restoration method. Many of the pumps today operate at flows substantially different from the BEP flow they were designed for many years ago. Why do pumps operate off-peak? Several reasons. We find that often the flow usage decreased through the years due to plant downsizing – less energy demand, workforce reduction, surrounding areas industry moved out, etc. Or, sometimes the pumps were oversized originally “just in case”, but, with running experience, a proper flow is lower than at best efficiency flow point. The extra capacity is thus not needed – so the pump is throttled, - and that is at big efficiency loss.
Pumping Machinery can redesign the impeller to exactly fit the new flow, making it a new BEP. You will keep the same casing: a new impeller design can be fitted - into same casing, with no piping changes. Our knowledge of pump hydraulics is coupled by our ability to produce, and test, if needed, your pumps to verify and compare the efficiency improvements and energy savings:
Hydraulic background: our impeller design process begins with the hydraulic analysis of the pump internal hydraulics, constructing so-called velocity triangles and the inlet and exit of the impeller:
Then, a blade loading is evaluated, by constructing velocity and pressure rise diagram thru the passage of the impeller, on mean (camber line), hub and shroud streamlines of the impeller geometry. Loading diagrams are judged by our hydraulic designers (see ref. Pump Handbook, and similar sources), to access possibility of internal flow separation, on-set of suction recirculation, cavitation issues, excessive friction, etc. – all of which can lead to hydraulic losses, and lost performance, i.e. low pump efficiency and excessive operating energy cost:
If required, a full 3-D CFD analysis of the blade cascade can be performed, to fine-tune the design, to perfectly match it to a new set of hydraulic conditions:
We can help you identify and evaluate your potential “money-burning” pump(s) and do an upgrade – right to the bull’s eye of the Best Efficiency Point!
Contact: Rick Mathis, Pumping Machinery, LLC, 770-310-0866
www.PumpingMachinery.com DrPump@PumpingMachinery.com
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