After washing my biodiesel a few times I dry in my steel tank while circulating. My drying tank has a band heater and an inline 240W heater, I like to heat the biodiesel up to 180F and circulate for about an hour, this does the trick. My question is how hot can I heat the biodiesel, it starts smoking a little around 180F ?
You can save some energy if you heat to 125f, drop in a bubbler, and blow air on the surface.
what you are seeing is water vapor not oil smoke . DO NOT take the temp above 200 F or your asking for trouble untill you have removed most of the water. you risk a very nasty " burp" from boiling water in your oil .....scott
As the biodiesel heats it is circulating, so I am guessing the water is evaperating as the pump runs. I am still wondering how hot can you heat biodiesel?
The reason you are not getting an answer is, IMO, that there is no real clear cut answer that is supported with data.
However, there are issues with too much heat, in theory at least. As the bd is heated, you accelerate chemical breakdown and polymerization. The extent to which these happen and the extent to which they are issue is largely unknown.
Do you test for TAN? Have you considered testing some fuel which is heated to 190f and comparing it to the same fuel which is only heated to 125f, for example? I have heard of people who got elevated TAN from excessive heat in drying.
By the way, you may be seeing smoke. It probably depends on the BTU's per inch and the localized temp. near your heating element. If heat intensity is high, even though the entire batch is only at 180f, the local temp near the heat source could be high enough to cause smoke. I have seen it. Between 175f and 200f.
03 Dodge 2500 B100 homebrew
79 Rabbit B100 homebrew
I had this happen on my kitchen stovetop once with about 3 or 4 cups of crude/natural shea butter.
I had water washed it to deodorise it & was drying it on the stove in a small pot.
I had already drained most of the water out by pouring the oil off the water into a different container, then dumping the water into the sink, then pouring the melted shea butter back into the pot to boil it dry.
Anyway, the steam was boiling off peacefully, then suddenly farted off with about as buch power as a .22 bullet (not much power, but enough to do dammage).
It sprayed hot oil all over the kitchen like a grenade & burned me nicely. Good thing I am a weldor, or I might have cried out in pain (LOL).
Bottom line: boiling oil dry can be very dangerous. If this had been a drum of oil, I would have had 2nd degree burns from head to toe.
A guy here named BigblockChev is a practical minimalist brewer, and has a very simple, effective, system & he's able to make good esters in only one cone bottom poly reactor.
He uses a HF pump to push his WVO & finished esters through a steel pipe past a heating element & sprays the liquid back into the top of the reactor through a tube with the end crimped 1/2 way shut to fan the oil out for maximum evaporative surface area. Very safe & effective (simple & cheap too).
I heat my washed BD to 170 deg & it dries in about 2 hours. Once to 170 then heater off & pump runs for another hour or so. Cheers Dan