Hey Don
I'd like to talk about condensors again. I am determined to capture my Methanol from my Glycerin but have failed so far. I'm quite sure the problem is in the condensor. I know you and I went over this before but maybe we missed something.
I heat my glycerol to 180F and "vaporize". From there I run it through a 1/4" copper line in a downward direction about 4" into a 4" PVC pipe about 2 ft long that has approx 10 ft of 1/4" copper wound in it.
For cooling I have a circulating pump with a refrigerated storage tank. The water stays about 70 deg F throughout the process.
I slightly pressurize the vapor chamber with nitrogen. Someone suggested pulling a vacuum on the condensor line AFTER the condensor.
Do you have any more thoughts concerning this? I know we have beat this to death but I still have no luck. Appreciate any help.
Thanks Tom

 

Wow! I don't know how I missed this post Tom..........Must be my "oldtimers" kicking in! The problem has to be in your condenser. If your heating to the temps you say you are, you should have Methanol vapor pouring out of your "still"............I noticed that in my alcohol still the vapor is in the main tube, and the cooling water is running in the copper tube inside. Might be something you could try. Pulling a vacuum is also an option, but make sure you use a diaphragm style of pump that will not cause a spark! Call me if you want to, and we can talk it out.

 

Hey Tom
Lets talk about your condensor design. Your description left me with questions about it.

1. Does the copper tubing carrying the MeOH vapor come in direct contact with the chilled coolant?

2. Do you constantly recirculate the coolant?

3. How much pressure are you putting into the vapos chamber?


Here is a URL to a web page that describes several different types of condensers.
My personal choice is the Graham style with coolant in the jacket and vapor/condensate in the internal spiral.
It is important that the coolant be recirculated with inflow at the bottom of the jacket and outflow at the top.

Pressurizing the vapor chamber can raise the boiling temp of methanol. You really should not need to use that N2 because the act of boiling the MeOH should provide all the pressure you need.



Any questions post em and I will try to help. I have spent a few years in a chem lab.

 

First, I will clear up some of my condensor info I posted previously.
My housing is 3"x24" and is PVC with caps on the ends. The spiral Cu tubing is 5/16" and is approx 10ft long (coiled of course). The vapor comes in the top and out the bottom. The cooling water (constant flow) comes in the bottom and out the top. I don't know how much flow. It is recirculated from a refrigerated drum. The coils are in direct contact with the cooling water. I use Don's method of vaporizing the liquid. I choke the drain valve on the vaporizer to keep the liquid at the 3/4 level. As far as pressure, I don't know how much pressure is developed from vaporizing but I inject a VERY SMALL amount of N2 in the chamber for protection against fire/explosion (per Don's suggestion) The N2 regulator is turned down as far as possible and still produce flow. As far as the condensor, it is Don's design which you are probably familiar with.
I will try Don's suggestion to pull a slight vacuum on the vapor line (after the condensor) and see what happens. I hope you and he can collectively figure out what I have done wrong. I have been trying to find a cork with double holes to use in the vacuum bottle.
Thank you both for your help in this matter. PS Please post the URL you mentioned in your post.
Tom

 

[QUOTE=Tom D;7458374]My housing is 3"x24" and is PVC with caps on the ends. The spiral Cu tubing is 5/16" and is approx 10ft long (coiled of course). The vapor comes in the top and out the bottom. The cooling water (constant flow) comes in the bottom and out the top. I don't know how much flow. It is recirculated from a refrigerated drum. The coils are in direct contact with the cooling water. I use Don's method of vaporizing the liquid. I choke the drain valve on the vaporizer to keep the liquid at the 3/4 level. As far as pressure, I don't know how much pressure is developed from vaporizing but I inject a VERY SMALL amount of N2 in the chamber for protection against fire/explosion (per Don's suggestion) The N2 regulator is turned down as far as possible and still produce flow. As far as the condensor, it is Don's design which you are probably familiar with.
I will try Don's suggestion to pull a slight vacuum on the vapor line (after the condensor) and see what happens. I hope you and he can collectively figure out what I have done wrong. I have been trying to find a cork with double holes to use in the vacuum bottle.

Ok a couple of things to check:
1. Is the boiling chamber well sealed. If there is a leak the vapor will follow the path of least resistance.

2. Does the condensor slant down at a 45 degree (at least) angle if not you can get a fluid lock

BTW Have you been able to recover any residual Methanol from your BD with your set up and it is only the recovery from Glycerol causing problems or you get no condensate no matter what the feed stock.

I must have had a senior moment during my last post. SORRY !!!

Here is the URL (for real this time)
http://en.wikipedia.org/wiki/Condenser_(laboratory)

 

Ok a couple of things to check:
1. Is the boiling chamber well sealed. If there is a leak the vapor will follow the path of least resistance.

2. Does the condensor slant down at a 45 degree (at least) angle if not you can get a fluid lock

BTW Have you been able to recover any residual Methanol from your BD with your set up and it is only the recovery from Glycerol causing problems or you get no condensate no matter what the feed stock.



I must have had a senior moment during my last post. SORRY !!!

Here is the URL (for real this time)
Condenser (laboratory) - Wikipedia, the free encyclopedia[/quote]

Yes. Chamber is sealed good. To be sure, I will pressurize and double check for leaks.
The condensor is mounted vertically. I will change that.
At best, I have only recovered approx 3-4 oz from a 40 gal batch. I don't collect anything from the glycerol. One thing I was concerned about, after I drain the glycerol off the bottom of the separator tank into 5 gal pails that I seal, I heat the BD in the 55 gal separator drum BUT I open the vent at the top for 2 reasons 1. I'm afraid of building too much pressure while heating to 180F. 2. I drop a temp probe down the 3/4 pipe through the vent valve to monitor the temp. Do you think I am losing too much vapor? I don't know a better way to do it. Later I heat the glycerol in another drum and run that through the vaporizer and condensor. Maybe I am losing the methanol when I pour from the 5 gal pails to the drum.
By the way, are you familiar with Don's vaporizer? I will not discuss it on the Forum unless he approves it.

 

I dont know that moving having the condenser totally vertical is a problem. The problem is having it to much horizontal.

Very possibly MeOH is pretty volatile stuff. It would depend on how long you leave it open. Methanol boils at about 150 degrees, by the time you reach 180 degrees in a vented vessel you'll have lost most of it.

No I am not and I wouldn't ask you to disclose or discuss anything on a public forum that might have some proprietary concerns.

I have talked to Don, here, off and on for several years. I have a great deal of respect for his ingenuity, his ability to design and fabricate, and his scrounging talents; however, I most respect his knowledge of BioDiesel.

If he tells you somthing you can take it to the bank or, considering the present economic situation, stick it under your mattress.

 

[quote=Phydeaux88;7465910]


Very possibly MeOH is pretty volatile stuff. It would depend on how long you leave it open. Methanol boils at about 150 degrees, by the time you reach 180 degrees in a vented vessel you'll have lost most of it.

What is your method of vaporizing your BD and glycerol? How hot do you heat it? Do you heat it in a SEALED container? I will check the URL you sent and get some ideas from it. Anything you can contribute will be greatly appreciated.
Thanks Tom

 

You can cause vaporization of the MeOH component of the mixture by raising the temp over 150 degrees, the higher you raise the temp the quicker the vaporization will occur.

By leaving that valve open during heating you are providing an escape route for the vapors you are trying to capture. Close the vent. You want all vapor outflow to pass thru your condensor. In theory the open outflow thru the condensor should prevent excessive pressure buildup; however, many moonshiners have been killed by exploding stills. You can close the vent off by installing a pressure relief valve and alleviate that potential.
If the drum you are using as a boiling chamber is a standard 55 gal or similar, you can get a good idea of the temp of the contents by externally measuring the temp of the drum at a point remote from the heat source.
The concept of a "Nitrogen blanket" for saftey is good but it doesn't require over pressure, before you start just fill the headspace with N2 that will drive off any O2 and keep a fire from happening.