I have a few questions concerning the AE process.
1) What is the practical upper limit of the FFA concentration of the uvo that will still respond to the AE step followed by the transesterification step?
2) Has anyone used a two stage acid esterification process prior the the TE step?
3) What problems, other than draining the methanol/water from the 1st AE step, could one expect when trying to use a 2 step AE process?
Any info', experiences relating to 2 step AE processing followed by TE would be appreciated.
1) From my experience the upper limit for a single stage is about 40 acid number for us. I imagine that would be different for each set up.
2) We've had to do a double AE once or twice when the water was too high for the initial AE and it was a PAIN in the backside. The second AE needs dry oil again meaning that we had to re-dry the oil which of course removed the extra methanol as well, which meant using a LOT of methanol that batch.
3) Doing a TE after the AE always requires lowering the KOH amount slightly. After the double AE it required lowering it even more. I've used 7g/kg for straight TE, 5.25g/kg for post AE, and 4.5g/kg for post 2nd AE (using KOH). Depending on AE method everyone's numbers will vary I would assume.
I've run oil that was 50 KOH but others have run higher numbers 80-100..
is your setup able to handle the level of acid needed..black iron is ok for a little while. plastic or stainless is needed.
I've never dried the oil again between stages of AE. it would be interesting to try this. I would think a distillation to recover the methanol should be before drying.
speaking of distillation..if you have oil that needs 2 AE stages, you'll what/need a good methanol recovery setup..because you need 30-40% methanol to convert the oil to biodiesel.
'84 bluebird school bus, DD8.2L turbo( 4/2011, the bus tranny has died.. 8.23.11 bus driven to scrap yard )
2006 Jeep Liberty CRD - the wife's
99 dodge 2500 5.9l 24v..-mine
everything run B100 when its warm enough
I'm not well versed in the chemistry but is there a risk of back reaction with distillation?
Would a flash(y) evaporator with a condenser discussed elsewhere be suitable?
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