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Pilot plant digester mixing

Q: I would like to continually mix 4% DS anearobic sludge in a 1cu.m pilot plant digester(h/d aspect ratio 1.3/1), using an external pump system with 2 nozzle injections. Sludge throughput is 3l/hour. @ 37degC. Max. solids size = 10mm. What would be minimum injection velocity and flow rate required? Any other requirements i.e nozzle angles, nozzle, injection height, baffles, etc.?

A:

The answers to all of these  questions appears to be the reason for the Pilot Plant Digester.  If  someone could easily answer these questions, the pilot plant would not be  needed.  The pilot plant digester should be designed and constructed in a  manner such that the nozzle diameter and pump rate can be changed  easily to test what the minimum injection velocity and flow rate  is.  The nozzles must be easily relocated to test the effects of nozzle  angle, injection height, location, etc.  Baffles may be necessary to avoid  bypassing of the main digester flow.

The real question is how do  you scale-up results from the pilot plant size to the full-scale digester.   The answer to the scale-up question, must also come from the pilot  plant.  Tests need to establish whether maintaining jet velocity is  sufficient to maintain performance or whether flow rate has a more significant  effect.  Particle size and size distribution may have an effect on the  answer to the scale-up question since concentration if a factor on both flow and  particle suspension.

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