Hi chaps

I recently added a second heater and pump to my processor with the aim of speeding up my processing. I use what is effectively the GL 1-day method and the GL Eco-system.

I made a 150 litre batch (160 l WVO, 40 l methanol) and decided to measure the power input and time to distil methanol from the BD.

I use 6KW heating run from a Lister CS 12/2 stationary engine driving a 1950s Brush alternator providing 6KW. The engine runs on BD.

According to my cheap Maplin wattmeter, I used 5.72 KWh to produce 6 l of methanol at 93 - 95% purity in about one hour. I stopped distilling with a pot temp of 95C when the flow rate had fallen from the initial 100ml a minute to around 25ml a minute. The one thing I didn't measure was the fuel consumption of the engine, but Mk. 1 eyeball says not more than 4 l.

Value of recovered methanol approx £3 ($6 US)
Cost of recovery approx £0.40 ($0.80 US)

I will take more measurements, as I have a big batch of glyc to de-meth soon.

All the best

Pete

Another set of data from a 160 l batch:

The newly formed biodiesel, after glycerol separation, was heated from 60 to a temperature of 96 C to drive off excess methanol and 4.7 l of methanol at approx 95% purity were recovered. The energy required to do this was 6.2 kWH. I calculated the theoretical energy requirements to be:

Energy to raise 144 kg biodiesel from 60 to 96 C = 2.59 kWH
Energy to distil 4.7 l methanol = 1.139 kWH (latent heat of vapourisation of methanol approx 1100 kJ/kg)
Total 3.729 kWH, an efficiency of 60.1%.

I assumed that the specific heat and specific density of biodiesel was the same as that of vegetable oil, which is probably wrong :-)

I will measure the fuel consumed later today.

All the best

Pete

Fuel consumtion was 7.5 l for the whole process. The distillation part accounting for 45%, so fuel used by distillation was 3.4 l, at a nominal cost of £0.12 a litre making £0.41 or $0.82 US.

All the best

Pete

Thanks for sharing the data, Pete. Are you using a 6kw heating element. It appears methanol recovery is cost-effective as long as we're ignoring our time.

Do you think mixing would aid methanol recovery?
Jurgen

Heating is 2 x 3 kW, circulation used throughout, and I'm sure it does help methanol recovery, besides avoiding "burning" the elements and the biodiesel.

As far as the time goes, pump diesel just hit £1.169 a litre here. I just made 150 litres for £0.12 a litre, a saving of £1.049 a litre or £157.35 (about $315 US) on the batch. It took me about seven hours, start to finish, a "return" of £22.47 an hour. Consider this "return" as being after taxes of 31% too, and the figure gets closer to £30 an hour. It's not as much as I _can_ make in the day job, but I don't mind working for $60 US an hour :-)

All the best

Pete

Pete,

Question if you don't mind...

You're measuring the heating element only? What about pumps, specifically circulation pump power and I'm guessing that you use some type of pump in your condenser system as well?

Last week I did my first meth distillation and realized that in order to be as efficient as possible, I need to apply as much heat to the biproduct as my condenser could handle. What I also realized is that once I got to arund 4kw (on a single element), I started getting a popping sound and needed to back off.

My circulation pump requires 400w as well as my condenser circulation pump (but this will change downward to 40w once I install the new pump).

Thanks for the latent heat data. I didn't know what the number was. Now I can run the same numbers to see how I faire.

Steve

Awesome, sorry for the very long delay in replying!

Yes, I was measuring the heating element only, the pumps will add a further 300W (2 x 150W). I do not have a pump on the condenser side, I just use a large tank and rely on thermo-syphon effect. If the tank gets too hot, I let some cold in at the bottom.

All the best

Pete

It would work out even cheaper if you recovered methanol from the whole batch of bio and glyc together instead of doing it with bio or glyc seperately.

IIRC if you distill the glyc while it is till combined with the BD it sends the reaction in reverse.
This is the reason to fully separate the two and demeth them independantly.

Hi Luc,

well there are quite a few of us in the UK, and 1 or 2 on infopop here who are successfully demething the whole batch without acid.
I did one batch that seemed to work ok so I then did another two batches back to back to make sure it worked ok before going public, before that I spent quite some time reading on the tinternet about methanol recovery, and whilst everyone seems keen to say it will reverse the reaction if done on the whole batch, I could find no factual info/studies/reports from anyone who had actually tried it and proved it would reverse, it was just repeated verbatum.

I had demethed the whole batch accidentaly myself a few years back as a newbie and it seemed like good fuel to me but more experienced folks on here convinced me then it would be bad bio as it would have reversed! (this was well before 3/27 and other tests now available) by just repeating the old tale of reversal with no factual info, so I just mixed that batch a bit at a time into other batches, a few years down the line and with more experience I got thinking about it again and decide to try some experiments.

Try it on a small batch yourself and see.

And you are correct, it was repeated verbatim without any personal first hand knowledge.Seems that that aspect needs revisiting.

I have been reading the "demeth entire batch" thread(s) with great interest - I will be trying it soonest. I read GL's experiences with phenolthalein and HCl with great interest, but it seemed a bit too involved for me. If I can avoid the neutralisation phase and demeth the whole shebang in one hit, I will be a very happy bunny.

Will keep you all posted.

Regards

Pete