Reduced oil temperature in reactor ?

[farmerpete Junior Member Find all posts View Profile Close farmerpete]

I've been using straight veg and various blends with diesel in my Mercs and Landcruiser, but want to make " barely bio " ie perhaps a 60-70% reaction?
I remember reading Tilly mention reactions and required oil temps are tied in to process times ie cooler oil needs to be reacted longer.
If oil temps were approx 30 deg C how long would I process for with a pump that turns over the volume of oil in -say- 10 minutes?
Or 500 litres turning over with a blade or propellor so the vat contents was rolling over nicely?
Ball park figures
Cheers
PS I live near a 10,000 people town and Its getting hard to keep my oil suppliers. Anyone else finding this? The attitude seems to be anyone can take it.

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Reduced oil temperature in reactor ?

Hi farmerpete,
The rule of thumb is that for every 10C the temperature is reduced, the reaction time doubles.
The rule of thumb is that it takes about 1 hour for the reaction to reach completion at 50C.
So at 30C the mixing will take about 4 hours to reach a point where it will go no further.
This assumes adequate mixing vigor- less vigorous mixing will take longer and more vigorous mixing will take less time.

I remember there was a situation on another forum where someone was selling a reactor that had such limited mixing vigor that most people who bought one were unable to make biodiesel that would pass the 3-27 test in a single stage reaction.

PS- I have excess oil "runnin' outa' me ears". I am giving it away in thousand litre IBC's

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Reduced oil temperature in reactor ?

Sounds like Farmer Pete needs to make a road trip.

[smithy Senior Member Find all posts View Profile Close smithy]

Re: Reduced oil temperature in reactor ?

The 'rule of thumb' mentioned previously is not relevant to the transesterification reaction we use to make biodiesel. I have processed untreated oil outside in mid winter for the heating in a 1000 litre tank. After methoxide introduction the temperature has been no more than +5degs C.

I leave to mix for 1 hour and the resultant conversion is no less than if I used heat.

My oil for processing road fuel shows a conversion of 10 to 25% after glyc pre-treating. I then use 1 or 2 further stages and use no heat at all for the 1st stage. In fact a batch I completed this weekend which showed 8mls dropout using a 10/90 tube 'Warnqvist test' processed in a single reaction using 11.5% methanol and 5.9gms KOH/litre of oil.

In mid winter I warm up the oil to 20degs for road fuel processing. I use a very powerful 2hp pump running through a mixing eductor which produces 31psi pressure. The eductor is drilled out to 8.5mms. When I use a std 1/2" eductor the pump pressure rises to 71psi and the velocity is 28metres/sec but it is too much of a beast to use like this hence drilling out the eductor. The pump through the drilled eductor turns over a 200litre batch once every 30 secs.

Just getting back to farmerpetes post, 60 to 70% of the chemicals that would give you a 100% reaction would be reqd and 1 hour mixing (as long as your mixing vigour is adequate)
Remember that the conversion works exponentially, so in the first few mins most of the conversion takes place.

Also remember that with partly converted bio you would find it almost impossible to water wash, so a de-mething, settling then woodchip purification would be preferable.

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Reduced oil temperature in reactor ?

Hi Smithy,

The 'rule of thumb' mentioned previously is not relevant to the transesterification reaction we use to make biodiesel. I have processed untreated oil outside in mid winter for the heating in a 1000 litre tank. After methoxide introduction the temperature has been no more than +5degs C.

You will find that both rules of thumb are relevant to the transesterfication reaction we use to make biodiesel.
In your situation, because you have such powerful mixing things go faster than the the one hour it has been shown for most biodiesel reactors people make to reach completion
A number of years ago Myke from the SAFF said that their reactor reached 99% conversion in 10 seconds- but that is not what most people should expect to achieve.

I leave to mix for 1 hour and the resultant conversion is no less than if I used heat.

Yes, your mixer is much more vigerous than most so does not require an hour to finish the reaction.
The test would be to see how long it takes warm WVO to reach completion compared to cold WVO using your very powderful mixer

In mid winter I warm up the oil to 20degs for road fuel processing.

Why do you heat your oil to 20deg if it works just as good at 5deg?

[farmerpete Junior Member Find all posts View Profile Close farmerpete]

Re: Reduced oil temperature in reactor ?

Thanks People
More vigorous = less time

[tillyfromparadise Senior Member Find all posts View Profile Close tillyfromparadise]

Re: Reduced oil temperature in reactor ?

Hi farmer pete,

Thanks People
More vigorous = less time

Yes, More vigorous= less time.
Also, more heat= less time as long as everything remains a liquid and does not evaporate away.

Once people started using the 3/27 test to routinely check conversion, a number of people discovered that their reactor took longer than an hour to reach completion. Some people found that they needed to mix for 1.5 or 2 hours to pass the 3/27 test.
Some people found that their reactors were incapable of routinely making biodiesel that would reliably pass the 3/27 test using the single stage method.

The main problem turned out to be insufficient mixing vigor.
Because of their cheap price, many people had standardized on the small 1/2 HP clear water pump for mix in their reactor.
Some people were mixing batches containing as much 150 litre of WVO plus the methanol which is too much oil for such a small pump to mix reliably.

PS in 2004 Myke from SAFF posted-
"Energea claim their reaction takes 3 or 4 seconds (however i have heard this only second-hand). The Vienna University of Technology has developed a process that takes LESS THAN ONE SECOND for transesterification. "

This speed is unlikely to be achieved any time soon in the back yard

[Tony From West Oz Vice Chairperson of WARFA Find all posts View Profile Close Tony From West Oz]

Re: Reduced oil temperature in reactor ?

Please feel free to experiment with extreme agitation, shorter or longer mixing times, temperatures or even the ratios of reagents, if that is what you would like to try.
The bottom line is that YOU are responsible for the quality of YOUR fuel.

I would recommend that you do some test batches using the proportions of reagents, temperature, agitation and time you plan to use for production batches and test the output quality.

If you wish to get an indication of the quality of your fuel then the 3/27 test or the 10/90 test as is often used in UK, will give you an indication of the fuel quality.
This is usually adequate for home biodiesel production. Basically, 1 part product in 9 parts of Methanol. Agitate and check for drop out. Any drop out (unconverted oil) indicates a lower than 100% conversion. The amount of dropout gives an idea of the amount of unconverted oil in the product but it is not an exact measurement, only an indication.
If using the 10mL/100mL ratio and you get 1mL of drop out, this does not necessarily relate to 10% unconverted oil.
This may still be an adequate fuel for some engines. The choice to go for >95% conversion is yours, based on the engine you are using it in.

What we would appreciate though is for you to document the oil quality (titration result), processes, and the variables you have used, along with the impact on your fuel quality, and for these to be reported onto the forum so others can see what works for you.