Drip Drying Water Washed bio

[dgs]

More of an observation really. Because of the recent bbb and not knowing my fuel requirements on my return I decided to process a 200 litre batch during the week of the bbb. I water washed the bio and left it stood in the wash tank.

Approx 8 days later and to my surprise the bio was totally clear before drying. (I'm sure many of you have noticed this before but as I usually dry the day after washing, the bio still contains suspended water)

I tested the water content at 860ppm and then dried as normal. Water in bio becomes suspended at about 1000ppm depending on temperature so the result was probably predicted.

Before I used the IMB turbo dryer I dried by heating and bubbling ambient air with a small compressor. When I got my S/B I was always disappointed that the water level was always between 8 and 900ppm. This is similar to a lot of the samples I have tested using the spray bar/ring method.

I probably used my old drying method for a couple of years with no issues (water content 8 to 900ppm)

Does this mean that we are all wasting our time and energy drying our bio when we could just as well be leaving it to stand at least a week in the tank.

This result was after standing 8 days, I wonder what it would be after standing 2 weeks or even longer?

[Julian]

Did the water drop out or evaporate?

I've noticed part dry samples in jam jars don't drop water, but they appear to evaporate from the peripheries leaving a cone of cloudy bio in the centre of the jar.

[dgs]

It dropped out Julian.

I had two 50/50 tests on the kitchen windowsill a few years ago ( had photo's on here via tinypic but they seem to have gone) one was w/washed and one just demethed and settled. the water dropped out of both the bio layers, so both were clear during the day. At night they both misted again but the w/washed one was good for 3degs lower than the settled one.

I assumed it was the mono's in the settled sample causing it.

The point I as trying to make is if the water can only drop out if it is suspended ( so the sample is misty) it will get to a point where no more could drop out. Maybe having the temperature reduced would help, a little like freeze drying.

[neisel]

I've been leaving my bio standing for a few days after finishing the water washing for a while now. While it never goes clear it does drop water out for days, on a diminishing return basis.

I've never left it 8 days before. I just this a.m. turned the heater on to dry a batch I made that's been sitting around longer than usual inspired by this thread, since the 12th or 13th. I've pumped it  for a few seconds every couple of days to make sure any water in the pump or plumbing gets back into the main chamber & has a chance to drop. No more water is dropping out now & it's still cloudy.

I've notice it takes a lot less energy to dry bio which has been sitting around for a couple of days than freshly made, freshly washed water rich bio, which won't come as a surprise to anyone. Instead of heating to 80ish & leaving the element on for 2+ hours & pumping for 4ish hours I get it close to 60, turn the heat off & pump for a couple of hours, which may be overkill but it does make crystal clear clean dry bio.

Speaking of energy, I think that as I've become better at this I've radically reduced the amount of energy my process uses. Once upon a time I had 160 litres hot from beginning to end, sometimes reheating over a two day period. Now I heat the feedstock up to about 40 right at the beginning (only so my thick, sometimes barely pourable NaOH based glyc will not overwhelm my pump when introduced &, after glyc washing, drop out & separate properly & quickly) process at ambient & only turn the element on for 1 hour max at the very end to dry. Less than 2 hours instead of 4-5-6 sometimes 7 back in the bad old days.

[RichardP]

I always try to have a 'batch in hand', so when my dispensing drum is about empty I have a batch washed but not dried waiting to be finished & filtered, this can be standing for a few weeks after washing is done but before drying it.
As said, water will drop out , I use a 220ltr plastic cone for washing and it's easy to see how much has dropped, sometimes 1/2L or more after the initial settling and draining post washing.
I've never seen it completely clear, though when the heater is turned on for drying there's no popping/crackling with water, and it is a lot quicker to dry.
I have left an old glass vinegar bottle with wet bio in it standing open for a few weeks and that does go very clear with water/grot dropout, but how dry it is I don't know for sure.

[dgs]

Interesting posts, thanks.

Just a little associated story here. Two local bio friends have recently removed their DPF's and had the ECU remapped. They are both expensive motors, one was £18k

One friend has gone over to water washing and dries just using heat and ambient air. I tested the his bio for water and it was very high (it must have been on the point of becoming suspended at 950ppm)

Using this biodiesel the sedimenter warning light has come on and apparently when this happens the engine seems to drop power (as if in limp mode)

So maybe (depending on vehicle type) it is best to dry our bio so it is within the EU specs at 500ppm.

[neisel]

A question for the panel.

That batch I made in #3 is now dry. It will have to sit in the processor for another week before I can decant into containers.

Will it attract moisture from the atmosphere & need re-drying, do we think? It's in a dry shed in a non airtight (has a lid) processor. I could make it more airtight by covering with the stuff I use to insulate the tank if need be.

After 20 hrs. in the fridge. The label you see is on a mustard jar behind the jar containing the freshly dried bio

[dgs]

It does absorb moisture but it depends on temperature, how dry the bio is and the R/H, if it is only there for 1 week I wouldn't worry too much.