Coffee grounds ... possible cause.

[Julian]

I've suffered badly from the dreaded brown sludge in the past and have never been able to work out where it comes from.

Tonight I watched a video about a couple who were having trouble with their diesel engines on a catamaran whilst sailing round the world.  They showed a brown jelly like substance in the fuel tanks which they said was poop from "bugs" in the fuel.  While what I've suffered isn't a jelly, the colour was identical (if it is bug poop perhaps my bug were a little more constipated!)

They only ever used dino diesel, but obviously took on fuel from some dubious sources on their travels and often had water in the fuel.  The claimed that the bugs existed in the water/fuel interface, something I've heard before.

For my part this seems a highly plausible explanation of the problems I've experienced and it would explain how the IP got full of the stuff.  I'm guessing the bugs may be small enough to pass through the filter and spent their life shitting in my injector pump, the little buggers.  I've never noticed water in my fuel, but with bio being so different to diesel I wonder if there are bugs that can exist in pure bio.

Interested in the thoughts of others.


 

[Julian]

Thinking further on this ... my coffee grounds problem has been far worse in the last couple of years or so which coincides the period I've been processing at ambient temperature.

I'd surmise that hot processing and drying at very high temperatures as I used to would kill the bugs.  All seems to fit the scenario of bugs being the cause.

Dave ... I blame you for introducing me to ambient processing!

[knighty]

I read diesel bug is a lot more common now because of the bio % in pump diesel which the bugs can feed on

I had diesel bud in a steam cleaner diesel tank years ago... bought some treatment on ebay, tossed the whole lot in (about 10x more than needed) and changed the filter a few times... that fixed it

it's not the bug you need to worry about, it's the bug poo (that's what I read at the time anyway)


60'C for a few min kills almost everyhting

[dgs]

Thinking further on this ... my coffee grounds problem has been far worse in the last couple of years or so which coincides the period I've been processing at ambient temperature.

I'd surmise that hot processing and drying at very high temperatures as I used to would kill the bugs.  All seems to fit the scenario of bugs being the cause.

Dave ... I blame you for introducing me to ambient processing!

i've never experianced your problem Julian and must have been processing at ambient for quite a few years now.  However I do dry with the turbo dryer after settling post water washing until the bio is clear. This way i can dry at only 35degs.

Although I don't check every batch for water after 5 hours drying at 35degs the level has always been <200ppm. (the one time I checked pump diesel it was 158ppm with KF)

I hope it isn't the ambient processing but who knows.

[WesleyB]

One reaction that finished biodiesel has is called auto=oxidation .  A cause of the coffee grounds appearing material in biodiesel is a polymerization reaction of fatty acid esters than have carbon-carbon double bonds .   It was discussed on biodiesel forum Australia , years ago .   I found a description of that reaction on the internet .  Try key words Biodiesel Auto-oxidation in a search engine . 

[Julian]

I hope it isn't the ambient processing but who knows.

I was only joshing, Dave.  If it is bugs, I had the problem long before I started ambient processing.  I suspect if you have a bug issue it transfers through all the processes ... settling tanks, holding tank, fuel tank and fuel system.  To eradicate you'd have to start at the beginning of the process and treat/clean each item in turn.

[Julian]

One reaction that finished biodiesel has is called auto=oxidation .  A cause of the coffee grounds appearing material in biodiesel is a polymerization reaction of fatty acid esters than have carbon-carbon double bonds .   It was discussed on biodiesel forum Australia , years ago .   I found a description of that reaction on the internet .  Try key words Biodiesel Auto-oxidation in a search engine .

I had a very quick skirt through some of the results and didn't see any mention of the brown gue some folks get.

If it were oxidation pretty much everyone would suffer from it surely.  The bug idea seems to fit all the symptoms we see including the fact that some suffer while others never see it.

[Tony]

I've only had trace amounts of glycerol-like substance inside fuel components - but I put that down to a small amount remaining in the bio itself.

As for oxidisation, my bio is usually stored in open top 120l containers for extended times.  I guess if anything drops out of that from oxidisation it doesn't end up in my fuel because they are all top-skimmed, but I've not seen any issues with this.

I know someone locally that ran on veg that had something grow in his tank, but that was like a jelly slime and it got absolutely everywhere - had to drop the tank and wash it all out.

[countrypaul]

One reaction that finished biodiesel has is called auto=oxidation .  A cause of the coffee grounds appearing material in biodiesel is a polymerization reaction of fatty acid esters than have carbon-carbon double bonds .   It was discussed on biodiesel forum Australia , years ago .   I found a description of that reaction on the internet .  Try key words Biodiesel Auto-oxidation in a search engine .

Auto-oxidation and polymerisation are two dfferent things. If you leave a little veg oil open to the air for some time it will form  a sticky mess like treacle due to polymerisation. Auto-oxidation can trigger polymerisation as the oxidation process can create free radicals that can initialise polymerisation. An example is the two pack car filler, or wood filler where you mix a pea sized amount of "hardener" with a golf ball size amount of filler.  The hardener normally contains a peroxide such as benzoyl peroxide to initiate the polymerisaion process. Without the hardener the whole process can still take place but very slowly. I don't know it a UV lamp could acelerate the hardening process.

[WesleyB]

From memory , without reading it again the auto-oxidation reaction causes a biodiesel molecule with a carbon carbon  double bond to connect/bond to a second biodiesel molecule that also has a carbon carbon double bond in the fatty acid . That makes a dimer , with double the molecular mass  .  Not all the fatty acids in biodiesel have carbon carbon double bonds bonds , but a percentage of them do .  The solubility of resulting dimers is different than simple biodiesel esters .  Contact with metal , oxygen  and maybe water influences the initiation of auto-oxidation reaction in biodiesel .  Light might be a factor if it's not in darkness .