Drying can't get rid of slight cloudiness.

[neisel]

Just finished a batch & am a bit stumped.

Nothing unusual in the normal procedure, 145 litres, 2 stage, KOH & methanol, water washed 5 times & then dried. Feed stock quality was lower than usual as I wanted to use up 4 cubies of thick, nearly solid oil that I didn't want sitting around all winter.

I started drying at a higher temp (80) than normal & then left the heat on for about the first 45 mins, leaving the processor on to run for about another 5 hours just circulating the BD. It was still about 55 degrees when I turned the processor off, thinking the job was done.

Tested it a couple of times towards the end of the drying run & it was crystal clear when hot & remained so when cold from the freezer but overnight in the fridge it went slightly cloudy. Did another test the next morning after the BD had sat overnight & was at 30 degrees, leaving out the freezer & straight into the fridge where, again, after several hours it went slightly cloudy. Oddly, on both tests it remains slightly cloudy when brought out of the fridge & is allowed to sit for hours to bring it back to room temp. The BD batch, still sitting in the processor, remains crystal clear.

I can't believe there is any water still in it & can't understand why it would remain slightly cloudy when at room temp.

Any thoughts?

Can I use it as is or do I need to re-dry it (even though I believe it to be dry) or is there something else going on here?

[dgs]

Send me a sample niesel and I'll test it for water. If it is ok at least it would eliminate one thing.

[neisel]

Thanks, just PM'ed you asking what quantity you'd need.

Despite my feeling it is dry I can't really see it being anything other than water in the BD so I think I'll re-heat & re-dry for a couple more hours in the meantime, see if that brings about any change.

[dgs]

Replied niesel, cheers.

[neisel]

Well, reheating to 70 & drying for another 3½ hours cleared that up.

I've never had a batch that has required such a long time to dry properly, all told about 7-8 hours. Very odd.

dgs, ta for the offer of the test but don't think it's necessary now.

[dgs]

no probs, pleased it's now ok.

[Bio-boy]

This is a strange one and one that I can relate too. I too have had a similar scenario whereby the odd batch takes significantly longer to dry than others. All of which are 100% 10/90 test passes. However, I have noticed on occasions that whilst washing, the odd batch does require considerably more cleaning cycles to obtain the crystal clear water upon draining. It is these batches that appear to give the problems. It takes me on average to 3hrs to dry a batch but occasionally it can take 5hrs to achieve the necessary clear biodiesel. I leave the heat on during the whole of the drying phase and only heat to 60deg.

The reasons behind what we are seeing is a complete mystery to me also.

[dgs]

I tested a sample for someone on VOD last week that looked exactly the same. It was 900ppm.

[Bio-boy]

I tested a sample for someone on VOD last week that looked exactly the same. It was 900ppm.

If I recall rightly soap was also up on that sample too. I have learnt over the years that making biodiesel is a very straight forward process. There are very few things that can cause irregularities or problems. If your fuel is cloudy and yet you have had good results following your 90/10 and 50:50 shake test then the cloudiness will only be excessive water.

I had issues following the recent build of my new processor but due to the quantities I make each batch the drying was initially inadequate. I have since improved my process/processor enabling me to produce 10ppm soap and 225ppm water content per batch. These results signify extremely good bio and turn around is 18hrs from start to finish.