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using vacuum for methanol recovery
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I'm thinking about doing methanol recovery right after the batch passes 3/27 test. Bump up the heat gradually after the reaction. But will I get good results without separating the bio from the glycerin? I don't think I will be able to maintain high enough temperatures if i use the pump to circulate the batch,but I think the exposure would help vaporise the methanol. Also I think some brewers are using vacuum pumps to help lift the vapors .Where do I get one of these pumps?
 
Location: western new york | Registered: November 19, 2008Reply With QuoteReport This Post
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From what I have read, demething without neutralizing the caustic will lead to a back reaction. This is the purpose of GL's push/pull setup, we use acid to neutralize the caustic and then keep the temps at 70C or less under vacuum to minimize the risk of a back reaction.
I use a vacuum pump with success however you will need a second condenser to go between your collection vessel and the vac pump to avoid getting methanol fumes into the pump which is very dangerous. GL's method is much more elegant and also safer by using a venturi and separate bath of canola oil for the vacuum pump. See here for GL's design. Here are some not so great shots of my old setup...
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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I'll have to study the GL processor. It's had my curiousity for a couple of months but I don't understand how it works .It looks to complicated to me. One thing I worry about with my present system is a heating element burning out while I'm doing a batch of bio and igniting the methanol. It's probably even worse trying to demeth a batch of glycerin.
 
Location: western new york | Registered: November 19, 2008Reply With QuoteReport This Post
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The push/pull is not as complicated as it looks. Its just a regular Appleseed style that has some extra plumbing to reverse the flow of oil so that it can PUSH up through the glycerin in the bottom thus keeping it out of the circulating pump while demething. The vacuum pump is a separate heated tank with a venturi and pump to create the vacuum. The pump circulates the canola (rape seed) oil through the venturi which draws a vacuum on the reactor PULLING the methanol fumes into the canola oil tank. The canola is heated enough so that the methanol just evaporates out of it into the condenser where it will condense and drip into the collection vessel.
Does that help?
Yes I agree that the heating elements are a hazard without proper safety devices in place, as I have discussed here in depth. The idea is to make sure that the element can only be on when completely covered in fluid, no oxygen = no explosion in the event of an element failure. This is still not ideal however as the elements are not intended for this application. They should be much more robust with a much lower watt density to mitigate the shorting out hazard.
On my new setup I am going to use a biodiesel fired boiler I am making out of an old oil fired water heater to do the heating, much faster, way cheaper to fuel and safer with the right setup...
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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My budget won't allow me to ungrade to a different processor at last this year. That's a better diagram than one I printed a few months ago. I have some under-reacted bio to re-process and then try to run in my furnace. Maybe this weekend if its warm enough. Your going to use a biodiesel fired water heater ,which is a good idea. You will eliminate the electric heating element ,plus use the product to produce the product. My heating element is wired for 110,which I think will limit burnout as long as its covered with WVO. I have a propane cylinder (100 lb.style)that I used for my first reactor. I didn't take me long to realize it was to small and that it was going to take forever to make any biodiesel, but I'm thinking maybe I can used it to de-meth my glycerin. As long as it doesn't clog or burn up. I was reading in a recent post about the reaction being reversed when trying to de-meth a bio glycerin blend.
 
Location: western new york | Registered: November 19, 2008Reply With QuoteReport This Post
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