An update after trying 3 batches using 7% pre-wash.
Pretty much got this nailed down now & am pleased with the results.
Yesterday's batch was 140 litres of disgusting, stinky crap that I have been saving over the winter, waiting for hot weather. Some liquid, some solid, some very solid, LOTS of bits of batter & other crap, and wet.
Heated & circulated, dropped out 5 litres of water which apparently wasn't all of it judging by the 1st stage conversion ratio, glyc washed with 18 litres.
16% methanol, 5.8gpl KOH, poor conversion with 45% drop out. Using same ratio of meth & KOH got a cloudy 100% conversion on stage 2.
Left the new glyc in & venturi'd in 10 litres of hot water for a 7%-ish pre wash, circulated for 15 mins & when dropping it out after waiting an hour I took a little more out than was strictly required to make sure I got all the soap. Doesn't really matter as I run all the water wash drop out through a settling Burco to recover any fuel for the next batch.
This seems to have worked well as 3 x 15 litre hot water washes @ 70-80 degrees later I had a crystal clear 50/50. The high temp also saves time & speeds up the drying stage when I get to it.
In the past I've been frustrated by having to do too many water washes, sometimes w. washing would take as long as every other part of the entire process combined. Now with this method I can make a complete batch in one day, albeit a long day if I use sh1te oil.
BTW, never had an emulsion (3 batches) & now do not introduce any acid or anything else to prevent one. It seems to work fine without acid.
