nope, but thanks for enlightening me, I just thought it was relevant to some of the concerns being raised in this one.
have a good one
larry

When I first read about this processor my immediate concern was that I didn't think a circulation pump would work under vacuum. I read all 19 pages so far and it's actually been brought up twice but I am still concerned or don't understand. I thought operating a circulation pump under vacuum didn't work for two reasons.
1. It caused cavitation which made it spin without pumping anything.
2. The seals in the pump weren't designed to operate under a vacuum and so air would leak in and/or the seals could get damaged.

I believe one of the responses to someone else's concern on this matter was that oil didn't cavitate as easily as water. But suction is added to remove water in the beginning and added again at the end to remove methanol. So wouldn't the water or methanol in solution cavitate in the pump under vacuum especially since it's being heated as well?

The cavitation would be cause by evaporation of methanol but, the evaporation will keep the vacuum from falling too quickly so as the pressure falls the methanol content does too.

Yes the pressure drop at the pump inlet can cavitate, but I don' think it will be bad enough to be an issue.

You can allows throttle the pump output to decrease the pressure drop at the pump inlet.

Hmm sorry to "hijack" the current discussion under this topic but I'm keen to get a response to my question

Ive just priced some phenolphthalein powder and they wanted $220.00 Aust per 100gms .. Does this sound a reasonable price ??

Are there ways around dosing the whole batch

Stuart


Stuart

quote:

Originally posted by Ozzie:
Are there ways around dosing the whole batch

They've discussed this a bit. It would be possible in theory to do an acid titration. The problem is that the acid is added after the glycerin and bio is reacted and separating. That means the glycerin will be toward the bottom and bio on top and there's just no way of getting a sample out that represents the state of the whole thing.

I have a feeling that because the amount of "extra" catalyst per liter is a constant. After you do this a few times the amount of acid per liter needed to drop the Ph and prevent the reverse reaction will be a constant too. From then on you can just add that amount. It's just that this is a new procedure and if you're going to be on the cutting edge of the science sometimes you have to buy truckloads of phenolphthalein.

I'd like to try a plan-B method of acid titration (I'll call it a 2-stage method):
drain a little settled glycerin from the bottom. Acid titrate it. Drain a little biodiesel from the top. Ditto. From experience or other calculation figure out the ratio of glycerin to biodiesel to calculate how much acid to add to the batch.

The fault in this concept is the unknown distribution from top to bottom in the processor. The two sample mentioned may not be reliable indicators.

OTOH, a single sample from the glycerin in the bottom might be "just as good" as the two I proposed above, if the right multiplier is possible to find.

I just hooked up my rapeseed tank with a mazzie venture and am able to draw 25" of vacuum on my tank. I have not tested it with heat yet just cold water so I dont know how much I will lose as the water/methanol gets boiled off but it looks promising. It took 15 min to get to 20" at full batch level.

quote:

Originally posted by Nolte919:
........... if you're going to be on the cutting edge of the science sometimes you have to buy truckloads of phenolphthalein.

Hmmmm more like the bleeding edge

Thanks for the feedback chaps

Stuart

Drewry

Great Vacuum! So what Pump & Mazzei sizes did you finally settle? Did you just downsize the Goulds J04853 pump to 3/4" to make your setup work? Which model Mazzei injector did you use? (there are a few models that are 3/4").

Thanks
Doug

I also have a question that I need a little help on.


Thanks Tony. I am making something up here and would like to know what you think.

Here is the end question:
If I use solder to attach a thermocouple to the bottom of a thermowell, will the solder conduct most of the heat so the thermocouple will give me more or less adequate correct temps?

The problem I have? I am installing 3 PIDS and thermocouples (temp sensors) into my system. I didn't realize the thermocouples were not 'leak proof.' If you look at them closely, basically you have the sensor passing through a nut that has male thread on in it. I assumed this thread was part of the sensor but they are separate and so basically there is a gap between the sensor and this nut so you can't just screw it into a 1/8 fitting and according to tgomes, this thread is a Pain in the Arse - clearly making matters eve a little more complicated. As a solution, I bought some thermowells (sealed brass things that extend into the liquid) but they are bigger then the thermocouple sensor - like 1/4 inch thermowell compared to a 1/8 sensor. So there is no tight connection from the sensor to the well. I was thinking to cut up some solder, put it at the bottom of the well, heat up the well and let the sensor attach at the bottom. Do you think the solder will conduct all the heat? Now that I got brass, solder and the sensor in there, will I get relatively close readings? It should would but I am not certain at all.

Thanks
Doug

Doug and all,

the venturi I am using is the 3/4" one from b100. I tried the goulds pump with it and it overloaded the venturi and created very little vacuum. I swapped the goulds with the NT clear water pump and created 25" of vac at the venturi a little less vac in the tank, I have not added the heat to the tank yet so I do not know how much it will affect the vac. I am sure that a larger pump and a 1" venturi will do better when the methanol starts boiling under vac.

quote:

they add about 100ml of Sulfuric Acid directly to Methanol and let it react for hours and then add the base (K/NaOH). So there is little real world evidence of creating Dimethyl Sulfate.

Actually Demethyl Sulphate or Me2SO4 is created in the real world. It is why the Acid stage of the two stage Acid Base reaction works. Me2SO4 methylates the FFA's and turns them into methyly ester; biodiesel. When they say react for hours they mean with the high FFA oil. As I said it's not so dangerous if you do it right and acid base people have been doing it right for a while now..

Late edit to correct my error. It is not why the acid stage works. That is a different reaction.

This message has been edited. Last edited by: Ant,

Doug: yes, the solder will conduct the heat to the t/c nicely, but don't expect the solder to stick to the t/c. It'll simply be in close physical contact, imbedded in the solder. If there's a concern that it might work loose, pot it in epoxy after the solder cools.
Cheers,
JohnO

quote:

but they are bigger then the thermocouple sensor - like 1/4 inch thermowell compared to a 1/8 sensor.

This is normal, you can fill it with oil or thermal grease.

Jon

quote:

Originally posted by Ozzie:
Ive just priced some phenolphthalein powder and they wanted $220.00 Aust per 100gms .. Does this sound a reasonable price ??

As it is normally used, and as graham has stated he uses it, it is 100ml of phenolphthalein per 100 liters. This is usually a 1% or 5% solution and is much cheaper.

quote:

Originally posted by Alken:
................and as graham has stated he uses it, it is 100ml of phenolphthalein per 100 liters. This is usually a 1% or 5% solution and is much cheaper.

Hi Alken

Thanks for the post.. I was chasing powder as described by Graham (see below) .. If the receipe has changed can you point to the post

Stuart

quote:

Originally posted by GrahamLaming:
.................... add a 1/2 teaspoon of phenolphthalein powder per 100 litres batch and allow to mix thoroughly.

I stand corrected...I thought I had seen where he stated the 100ml at one point. Too many days and night reading and setting up my GL. Have to pay more attention and take notes.

I don't know how bad shipping is for you from the states, but I get some chemicals from ScienceLab.com and they list Phenolphthalein, Powder, Reagent, ACS SPL5404-500G as costing $168.36 for 500 grams...125 grams for $66.04 .

As I am making a dual 120 gallon processor with the rapeseed tank and condensor between and will alternate start times so I can basically run continuous. I am also using a tee with a sight glass on each side with a light behind it on each processor so I will be able to see the color change. The only shared plumbing will be the line to the condensor, with valves to isolate each tank. Anyone tried something like this before?
My oil supply is from the supplier for laura scudders, frito lay, burger king... and is their off spec oil.(out of date) Actually have to head down and pick up 500 gallons tomorrow. Anyone need some 4 gallon jugs? LOL, that is what they give it to me in...120 of them tomorrow. I also have my original 22 rests. I have been collecting from that titrates at about 4.

As my building of the processor progresses I will try to post some pics. Camera dropped from top of tank one day.

quote:

Originally posted by Alken:
I don't know how bad shipping is for you from the states, but I get some chemicals from ScienceLab.com and they list Phenolphthalein, Powder, Reagent, ACS SPL5404-500G as costing $168.36 for 500 grams...125 grams for $66.04 .

Hi Ken

Thanks for clearing up the receipe ... stressful time down under ... did my first run in my push pull and it kinda worked I have a few technical "issues" to resolve

Did'nt do the last step ... Phenolphthalein / acid .. dont' have the phenolphthalein yet

It appears to be an issue with shipping it "offically" from the USA .. I bought some on Fleabay and it's winging it's way as I type

Hopefully will be in a position to give the GL a full run in a week or two



Cheers


Stuart

Please post pics of your Push/Pull Processor!

Also, how you are injecting HCL and where in your plumbing are you injecting it!

Thanks,
Jim

quote:

Originally posted by Ant:
Actually Demethyl Sulphate or Me2SO4 is created in the real world. It is why the Acid stage of the two stage Acid Base reaction works. Me2SO4 methylates the FFA's and turns them into methyly ester; biodiesel. When they say react for hours they mean with the high FFA oil.

I'm not sure this is true. I've looked over a few esterification mechanisms and have not seen the formation of Dimethyl Sulfate in any of them. They do mention hydrogensulphate ions, however.

http://www.chemguide.co.uk/physical/catalysis/esterify.html
http://www.chemhelper.com/fischester.html
http://www-personal.une.edu.au/~sglover/CHEM120Topic%20G/sld003.htm

Conjecturing , in application, the esterification is thermodynamically-favorable to dimethyl sulfate formation.