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Need better pump for phos acid clarifier underflow

Need better pump for phos acid clarifier underflow

Need better pump for phos acid clarifier underflow

(OP)
I have a problem pump that is a constant headache.  It's an expeller-design centrifugal pump on the underflow from a phosphoric acid clarifier.  The current pump seal will not survive in this service, mainly due to low flow and high inlet pressure:

1.5 sp. gr. phos acid
20 - 30% solids
52 feet of inlet head pressure
60 psi discharge pressure needed
13 gpm typical, 140 degrees F

The most current solution was to cut the impeller down drastically, run the pump speed up high to help the expeller seal better, and keep the discharge control valve almost closed (~10%open).  Naturally this wears out the control valve quickly too.  The seal package lasts about 6 weeks.

Looking for suggestions for a better pump application.  Current ideas are a disc pump and a progressive cavity pump.  Anything better out there?

RE: Need better pump for phos acid clarifier underflow

We use peristaltic type pumps on metallurgical thickener underflows in certain circumstances. They work OK but you may (or may not) have some difficulty finding a suitable liner.
Have always had trouble with expeller seals unless the application is benign. There is probably a suitable flushed mechanical seal but you may have to put up with a little dilution. Stay away from cartrige type seals as they fill up with crud and are difficult to clean out.
Chas S Lewis in St Louis make vertical shaft submerged impeller phosphoric acid pumps (no seal needed) but I am not too sure of their solids capability. They would be worth a call. I have only used their sulphuric acid pumps which are brilliant even if they look a little old fashioned.
Beware of mag drive pumps as the solids could cause problems.

Cheers

Steve McKenzie

RE: Need better pump for phos acid clarifier underflow

(OP)
I'm familiar with the Lewis pumps - we use their horizontal propeller pumps in our forced circulation evaporators.  The peristaltic pump idea is intriguing.  There are some elastomers out there that might work - chlorobutyl comes to mind.

RE: Need better pump for phos acid clarifier underflow

A hose pump may be a good choice, however, the temperature may be a problem with an elastomeric hose.  A good choice might be Periflo at www.periflo.com as with their AMP series.  We're a distributor in the mid-west USA for them.  Give Chris Miller at Periflo a call at 800.860.2983 and he should be able to help you out.

RE: Need better pump for phos acid clarifier underflow

(OP)
Is this weird or what?  I got a quote from Chris Miller last week.  We're hashing out the correct polymer to use at the moment - thinking viton might work, but checking on availability.  

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