Methanol Recovery headache - Diesel Forum

yaric008 · 09-16-2007, 03:48 AM

How much methanol should I expect to recover when making 50 gallons of bio and using 20% methanol. I think it should maybe be around 2 or 3 gallons but that seems excessive... We finally got our reactor online today and did the reaction phase at 120F then turned it up to 150F and opened up our condensor. At first we got a few drops, maybe a few milliliters, but then it stopped. My friend was like.. maybe that's all we're going to get... But i didn't buy it. Anyways, we opened valves to the atmosphere on the top and nothing would come out. So after a few mins for whatever reason we turned our vacuum pump on the water heater and methanol just started pouring out of it. Basically what it seems like is that the methanol is all in vapor in the water heater but it doesn't want to come out. There is no driving pressure. So wth... how to get it out? Maybe it was condensing in my condensor before it was being able to get out, therefore just dripping back into the tank?

Murphy2000 · 09-16-2007, 01:13 PM

Your temperature of 150 isnt high enough and the methanol wasnt boiling.

When you turned on the vacuum pump, you lowered the boiling point of the liquid and it started to boil.

girlmark · 09-17-2007, 04:47 PM

Hi,

YOu're missing a few basic things about the process. In order to get it to boil, you have to continue adding energy to the pot- so a thermostat (which only adds energy when it turns the heating element on) won't do it.

A controller for the heating element is the piece most people miss when they first build these things. You want to temperature AT THE CONDENSOR to be 150 or so (maybe up to 170 at the end of the process, the boiling point would indicate that a lot of water was also vaporizing from near the element). It doesnt realy matter what the pot temp is. Temperature controllers can be variacs or other 'dimmer' (don't use a light dimmer, not big enough at 300Watts). I have used a Harbor Freight router speed controller to vary the heating element wattage, but boy is it a cheap piece of crap- a bit worrysome with this dangerous procedure.