Venturies and viscosity

[Julian]

Been thinking about this recently.  I've got a vacuum gauge on my venturi and its performance varies quite markedly with viscosity.

Nothing new I know but I was wondering, if I ever get round to building my square processor which has been at the planning stage for about 5 years now, would there be any merit in building two venturies into the system ... one to dry oil and one for drying bio?

Anyone have any thoughts on the subject?

[Tony]

Hmm, interesting idea.

I'm also planning a square processor.  Again, had the bits for a while, just need to spend some time with the welder.

[Julian]

Yes, I think square is the way to go from a space saving point of view, but dead spots in the corners is a little concern.

I'm hoping a combination of Frankinpump and Heather running simultaneously will create enough turbulence to scour out the corners.

Back to the venturies, we really need advise from someone who's tested different sizes and designs.  I wonder if a nomograph type of thing could be drawn up ... viscosity vs. flow?

[Julian]

Another thing that may be worth a thought ... how about a couple of condensers.

The fist one recovering heat to a pre treatment tank and the second a normal water cooled version,  Probably wouldn’t be too efficient given the ability of oil to transfer heat, but it should offer a lttle energy saving.

[Tony]

When I was doing my most electrically intensive process (heating oil to 105C to boil water out) it cost approx 10kWh to produce 125l of fuel.  I doubt that more than 10% of that could be recovered by preheating oil, and 1kWh is about 12p - so it would be easy to spend way more on kit that would be saved in electricity.

[Julian]

OK, bad idea!

[Head Womble]

How about using the oil you want to preheat as the coolant in the condenser ?

[Julian]

How about using the oil you want to preheat as the coolant in the condenser ?

That's what I meant.

[Head Womble]

I thought you talking about using it in the first stage of the condenser, the SHHE bit.

You could use it in both stages, that may compensate for the reduction in heat transfer with oil.

Or just have a huge great big condenser with loads of surface area.

[Julian]

Although my SHHE works well and returns a reasonable amount of heat to the process, it also looses a great deal of heat to atmosphere, nice for keeping the shed toasty in winter, but wasted heat.  It was this loss that lead me to think about putting the heat somewhere useful,

[Tony]

That's the attitude of a proper biodieseller.  Forget the comfort brought by slightly warming my shed, how can I use the heat to save 10p a batch?!

[Head Womble]

Surely its not the money saving, but the warm feeling of not adding to global warming.

[Julian]

What ... no input from the venturi guru?

[Jamesrl]

What ... no input from the venturi guru?

Ye', strange innit!