Bypassing a Lot to Move a Little
Bypassing a Lot to Move a Little
(OP)
I plan to use a centrifugal pump to mix the contents of a storage tank by recycling 590 gpm. I am also considering using this same pump to deliver 40 gpm to a process. To enable this, I would bypass 560 gpm back into the tank. This approach would save a pump purchase, some piping, and an electrical install. Besides consuming more energy than necessary to move 40 gpm, are there obvious disadvantages to what I propose?





RE: Bypassing a Lot to Move a Little
Obviously, if you're only mixing for a short time per day and your process needs a constant flow, you'll be way oversized with the pump. Pumping all day recycling to the tank, just to get a small process stream pressure may overmix your product or heat it up, or heat up the pump. In any case, it will probably waste too much energy.
If you have to mix all the time, and if similar heads are required for both, just offload a bit to your process through a valve that you can regulate pressure and flows to meet your process condions.
If there is a timing mismatch, ie process is continuous, mixing is relatively short time, I really think you might be trying to do too much with one pump and your systems would be better served using two task specific pumps.
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Bypassing a Lot to Move a Little
I'm not sure I understand your point about the head being similar for the two processes. The flows I mentioned are based on hydraulic analysis of the proposed piping system. The tank is atmospheric, and so is the other process. I calculated the flows assuming equal pressure drop along the two pipelines, analogous to parallel resistances across the same voltage drop. I calculated the flow through each pipeline for various head values, then summed the flows and plotted the result against head on the pump curve. The flows I cited occur where my system curve intersects the pump curve. Any issue with my analysis?
RE: Bypassing a Lot to Move a Little
With a low head pump, probably not too much heating will ever happen, so perhaps not to worry about that either, but if you were running hi head, low flow to one side or the other, that could be an issue. If its low head, probably not to worry about it, as long as you keep the flows above 20% BEP, which you should want to be doing anyway (at least 50% I'd hope).
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Bypassing a Lot to Move a Little
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Bypassing a Lot to Move a Little
Steve
RE: Bypassing a Lot to Move a Little
RE: Bypassing a Lot to Move a Little
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Bypassing a Lot to Move a Little
A 2 hp pump for the 40 gpm process will only cost me about $1100.
RE: Bypassing a Lot to Move a Little
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Bypassing a Lot to Move a Little