Helpful tips to extend the life of your pump
Everyone wants their equipment to last a long time and not break down or wear out. Eventually it will happen, but you can take steps to extend the life of your pump and ensure its operating under optimum conditions.
The importance of pump efficiency
When a pump operates at a flow away from its best efficiency point, its efficiency is lowered. Consider: A centrifugal pump, operating at 80 percent efficiency at BEP, will operate at perhaps 30 percent efficiency at half flow.
The larger you pump, the more money you are losing. And this problem can translate into lots of lost dollars. For instance, think about a 1,000 hp motor, running continuously over the course of a year. With an estimated energy cost of 7 cents, these 1000 hp (746 kW), will consume 746 x 24 x 360 x 0.07 = $451,181 per year.
This happens at 30 percent pump efficiency. If the pump efficiency is improved or restored to the original peak of 80 percent, then the energy cost would be only 451,181 x (30/80) = $169,193.
You save $281,988 per year. Put your own numbers into the equation. But the point remains: Efficiency is not a small issue and equates to big dollars.
Why pumps operate off peak
Pumps operate off peak for many reasons including:
Flow usage decrease due to plant downsizing – there’s less energy demand, the surrounding industry moved out or the workforce shrank.
Oversized to start. In some cases, the pumps are just oversized to begin with and the extra capacity is not needed. The pump is throttled – and that’s a big efficiency loss.
The simple solution is to stop wasting money and get a smaller pump that fits your operation. But that’s also an expensive solution given the purchase of the new pump and the associated changed needed in the piping.
Changing your impeller
Another way to solve your problem is to keep the same casing, same piping, and just change over the impeller. A new impeller design can be fitted into the same casing. There are no piping changes involved. The BEP point is basically shifted to the left – right where the operating point is -- and the efficiency is restored.
The cost of changing the impeller is significantly less than buying a new pump. And you will usually find your investment pays off in three to four months.
Sims retrofits impellers
Sims has been successful at retrofitting impellers. Our impellers are machines from solid blocks of structural engineered composites that are strong as steel and good to 300 degree Farhenheit. From a cavitation standpoint they are better then bronze or stainless steel.
Handling to 15 percent of solids particulate is not an issue, and our impellers are resistance to most chemicals. Sea water, brine and brackish water do not attack the simsite composites.
They composite is 80 percent lighter then metal and can improve pump rotordynamics, and reduce shaft deflections, solving seal leak problems, improving bearings life, and saving couplings from failing.
How to get started
We can help you identify and evaluate inefficient pumps, and recommend a solution. To start, we need a pump performance curve and it’s desired operation point.
From there, we’ll estimate the radial thrust load, onset of the suction recirculation, and determine the best impeller design to get you to maximum efficiency. If, after having our evaluation, you still decide not to implement the upgrade, we won’t charge for the technical evaluation.
Check out Dr. Lev Nelik's Pump School for valuable information and training.