high solids sludge pumping

[flushman25]

I have been looking for a good engineering reference on the proper design/calculation of total dynamic head on piping/pumping system to convey anaerobically digested sewage sludge at between 25 and 30% TS. My references only are valid up to 10 to 12% TS (slurry). Any suggestions?

 

[micalbrch]

I suppose your sludge is not only digested but also dewatered?

I doubt that you will find a formular or a calculation program for that. Sewage sludge with 25-30 % does no longer have a measurable velocity. The pressure when pumping this kind of sludge can be estimated. Pipe diameter, kind of sludge conditioning (polymere or lime) and source of sludge (municipal or industrial) play an important role. With a properly sized pipe diameter you can estimate something around 0.5 bar/m. Take that only as a good guess. Provide some more info and I can perhaps give you a better estimate.

 

[flushman25]

The pipeline length is approximately 200 feet with 20 feet in elevation rise. The pipe diameter is 6 inch. How are you estimating the pressure?

 

[micalbrch]

Just by many years of experience. I did work in this industry.

O.k. Your flow should not exceed 20 GPM. Otherwise the friction loss will be too high with a 6" pipe. With 200 feet the pressure will be around 435 psi, assuming your sludge is mainly of municipal source and poylmere conditioned. 435 psi excludeds a progressive cavity pump, regardless what manufacturers may tell you. The only pump which can handle that is a hydraulically driven duplex piston pump. Weir, ABEL, Saxlund, Putzmeister manufacture such pumps. It is very expensive but the only pumping solutions which exists for this pressure.

I suppose you checked the alternative with mechanical conveyors? But that will only make sense if there won't be many changes in direction. Otherwise this option becomes expensive, too.

 

[flushman25]

Interesting. Across your many years of experience did you encounter any references or procedures to document the headloss and parameters for pump selection and performance?

 

[micalbrch]

Flushman25: I could document that but as I worked for one of the named companies I do not want to. From my point of view that would be against the forum rules. Perhaps I'm too fussy but...

Get in touch with these companies or with one of them. They should be able to provide you the relevant information. Usually they work with a kind of list which contains parameters like solids concentration, density, pipe diameter, sludge velocity, pipe material, sludge conditioning method etc. Such a list gives a very good and rather accurate estimate. I know that some people started to develop a formular from that list but you cannot trust these formulars. Cake pumping with piston pumps means that you must overcome the static friction which every stroke. The dynamic friction is not so much of interest.

 

[stanier]

I think Geho or Able pumps would have experience of pumping such slurries.

Try BHRA for papaers on the subject.

Suggest you have some laboratory tests carried out for the particular sludge as it will behave in a non-Newtonian manner. The yield stress and other properties may vary during the year depending upon the amount of fats and greases.

The WRc in the UK put out a papaer TR185 on te subject.

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[flushman25]

Thanks for the input everyone. I appreciate your help.