Trangia 25/27, Ethanol, and Acetaldehyde

Discussion in 'Stove Forum' started by SoylentPlaid, Oct 6, 2016.

  1. SoylentPlaid

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    Hello everyone,

    I was wondering if anyone else has had a problem with acetaldehyde production in Trangia 25/27 stoves using ethanol. I would like to hear what other people have done to remedy this problem.

    Because of the upper windscreen, the Trangia vents the exhaust gasses very close to the upper lip of the saucepan. When boiling or simmering without a lid over the sauce pan, acetaldehyde (being miscible) will find its way into the water/food. There is the characteristic flavor/odor that would be familiar to beer and wine makers. Granted the concentration of acetaldehyde is well below harmful levels, I find the taste off-putting for certain foods (e.g. steel cut oatmeal). Now when I cook using the sauce pans, I have to keep the lid on except when stirring (which increases the likelihood of boil over without careful simmer-control). Acetaldehyde is not a problem with the fry pan given the higher cooking temperatures and the use of oil instead of water. Now the burner is over 15 years old and has had some “rusty” alcohol go through it on one occasion (there was no other alcohol available). I have washed out the burner, but I have no doubt that there are iron particles entrapped in the wick. Could that be boosting acetaldehyde production? The one test, I suppose, is to buy a new burner and see if the issue persists.

    I would prefer to use ethanol since I use the stove around kids. I am very fond of the Trangia and appreciate its simplicity and tranquility over my multi-fuel stove. Basically I am just trying to maximize my enjoyment with the stove and would appreciate any suggestions.

    Thank you!
     
  2. shagratork

    shagratork United Kingdom Moderator, R.I.P. Subscriber

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    This is a strange but interesting post.
    I suppose you are talking about the acetaldehide that is natural in bread, coffee, plants and ripe fruit.
    I thought that ethanol oxidizes into acetaldehyde, which is then further oxidized into harmless acetic acid.
    I also thought that acetaldehyde naturally breaks down in the body.

    However, my knowledge is very limited and I presume that as you seem to be concerned about it, that there is a much bigger picture.
     
  3. SoylentPlaid

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    Hello Shagratork,
    Everything you mentioned in your post is correct. It may just be the nature of the cooker/fuel. My primary concern is the introduction of off-flavors in my food. When I cook steel-cut oatmeal in my Trangia, I want it to taste like oatmeal, not like it was infused with apples. I will often use up the leftover alcohol in the burner by boiling/heating some water. I then put the hot water into a thermos so that I may enjoy a hot beverage later. I am usually cleaning up the frying pan and the other saucepan and so I have nothing to cover the water with. When I open the thermos later in the morning, the water has that classic acetaldehyde taste and smell. Or I may have a saucepan and the lid in a pot cozy to continue cooking while I use the other saucepan on the Trangia. I am not concerned about any potential toxicity because the concentrations are so low. Cooking good food for friends and family, even out in the wilderness, is one of my passions. I just want the food to taste as good as it can.

    I am probably going to buy the Trangia Tundra 2 lid (have to go through a Canadian source, US retailers don't carry it) so I will have a second lid. This has just been banging around in my head for a very long time and I just came across this site a few days ago. I haven't seen anyone else ever mention this issue (i.e. off-flavor/smell in food). I thought that this was strange and made this post so that others could say: "Oh yeah, totally normal. Just keep the lid on and you'll be fine." Or maybe someone might say, "I had that problem, doing XXXX fixed the problem straight away."
     
  4. snwcmpr

    snwcmpr Subscriber

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    Do you think this issue is limited to Trangia? Or could this issue present itself in other DIY alcohol burners? Caldera Cone comes to mind. That's my go-to outdoor kit.

    @Hazet is another regular trangia user. Maybe he could add to your thoughts.

    Ken in NC
     
  5. Ed Winskill

    Ed Winskill United States Subscriber

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    Haven't noticed the phenomenon myself.
     
  6. SoylentPlaid

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    Thank you snwcmpr and Ed!
    Based on your responses it would appear that I am the only one having this problem. That is helpful. It must therefore be an issue with my equipment or technique. As I am using commonly available brands of denatured alcohol, I can rule that out. As far as technique, I follow Trangia's recommended procedure for lighting and using the stove. That leaves the burner and the use of the rusty alcohol. It has been quite some time since I took chemistry. I recall that metal oxides can act as a catalyst for turning alcohols to aldehydes. Unfortunately, it has been so long that I can no longer figure out if such a reaction can occur with iron oxide and ethanol. I will have do do some digging around. Since you never know the range of expertise you might find on any given internet forum, maybe there is someone who can chime in on this subject. I had originally though that the acetaldehyde taste was a natural consequence of using ethanol in the Trangia cooker (i.e. 25 and 27). I got around it by using a lid when I could, but then I saw pictures of people cooking in the Trangia with the lid off. No one posting the pictures mentioned an off taste or the need to cover the pot (other than to conserve fuel).

    Anyway, thank you again. I will get another burner and see if the problem persists.
     
  7. Normo

    Normo Subscriber

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    Never noticed it either. I'm not a chemist - would changing to a different form of alcohol help at all?

    The Tundra set is well made, but why not use the kit fry pan as a lid?

    An alternative may be the Trangia gas burner - I have one. They work well.

    Norm

    Edit. This post crossed with yours. You have already commented on some of the points I raise.
     
  8. Jeopardy

    Jeopardy Subscriber

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    Can you get the safety data sheet for your brand of denatured alcohol from their website? It may be that something other than methanol has been used as the denaturing agent.
    Regards
    John
     
  9. SoylentPlaid

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    Hello Normo and Jeopardy,
    Thanks for taking the time to reply. I have looked into the MSDS for the most recent brands I have been using. My current brand is comprised of ~90% ethanol with the remainder being methanol and acetic acid. My brand prior to this was an almost equal mix of ethanol and methanol with but 1% of methyl isobutyl ketone. The thing is that this has happened with both brands.

    I will be picking up another burner this weekend and check to see if it is an issue with the burner. I was hesitant to do so earlier if the issue would simply repeat. Given that other people do not seem to have this problem, I am hopeful that this issue may be resolved.

    Again I would like to thank you for your help.
     
  10. Doc Mark

    Doc Mark Subscriber

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    Howdy, SoylentPlaid,

    Years ago, we planned a backpacking adventure to Alaska. The first leg of it was supposed to be in Denali National Park, but due to an early season, heavy storm, our permits were revoked, and we ended up camping up close to the front of the Park. The person in AK who had promised to get fuel for our Optimus 81 Trapper, dropped the ball, and we had to make do with whatever we could find, which happened to be the reg bottle of HEET. Using it, the stove burned filthy, and very sooty, and all of our meals, which we had dehydrated ourselves, had a very rank taste. We could hardly wait to get back to Anchorage, so we could buy plenty of good, clean Methylated Spirits for the hardest part of our trip, which took place in the Wrangel-St. Elias Wilderness. THAT trip was far superior to the Denali portion, as we spent the entire time backpacking, via map and compass, from where our Bush Pilot dropped us off, to the pick up spot, where he arrived two weeks later!! WOW!! What a trip it was! Using Methylated Spirits, instead of the red HEET, the 81 Trapper burner as it should, with a clean smell, and NO infiltrating taste in our food. Is this the phenomenon of which you are speaking? We still use that stove, and it still works just it should, with Methylated Spirits. We'll never use the reg bottle of HEET again, unless it's a true emergency. Take care, and God Bless!

    Every Good Wish,
    Doc
     
  11. ArchMc

    ArchMc Subscriber

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    Hmmm...
    Several years ago I used a Trangia on a week-long trip, and I seem to remember a sweetish, apple-like taste that appeared in one of the dinners. Somehow, I never associated it with the combustion of ethanol -- just assumed it was something about the food (I used a lot of fresh vegetables on that trip). I don't recall if I cooked with an uncovered pot, but it seems as if you're not alone.

    ....Arch
     
  12. Spiritburner

    Spiritburner Admin SotM Winner Subscriber

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    I think I've been lucky as never had this issue. Probably because the right sort of alcohol is readily available in the UK plus I don't have a well refined pallet. I've had meths spill in my kettle & left a residual taste - that is horrible! I can vouch for the Tundra lid. Useful bit of kit when the frying pan is otherwise deployed eg for use on a pan off the stove if you're cooking involves a bit of pan switching like when doing a full 'English' breakfast.
     
  13. Normo

    Normo Subscriber

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    I'll be interested to hear how this resolves, as I've developed a lot of respect for Trangia gear.

    Regarding the burner that has had traces of rust in it, there are a few interesting posts on YouTube about washing out old burners with water, cleaning around the flame holes with a toothbrush and pricking to size if needed. Dry well because there is a circular wick inside. I will be interested to hear if this makes any difference. The quoted problem is low flame rather than taint - but I would be interested to hear the result.

    I'll see if I can replicate the problem.

    Norm
     
  14. Big Si

    Big Si Subscriber

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    I've been using Methonol for the past five years and never had any problems. Not noticed the smell or taste any where.

    Si
     
  15. snwcmpr

    snwcmpr Subscriber

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    "tundra lid"
    Does it pack into the kit with everything else?
     
  16. itchy

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    Interesting observation. I have not used the Trangia enough to notice this taste. But I have used it and the Optimus alcohol cook set enough to notice that these burners do generate a fair amount of irritating (to me) volatile products. I also attributed that to aldehydes, etc., from incomplete combustion (partial oxidation).

    As to the source of the problem. I don't think it is due to rust or other contaminants in your burner, but these burners are pretty cheap so it might be worth trying a new one. Atmospheric pressure burners, especially in an enclosed heat shield, just run rich and there will be incomplete combustion.

    Is methanol better? While acetaldehyde is a product of incomplete ethanol combustion, formaldehyde, a chemically-related but more harmful compound, will be produced from the incomplete combustion of methanol. Another reason not to cook in a small tent if it can be avoided.
     
  17. SoylentPlaid

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    Hello everyone,

    Problem solved. It was operator error on my part. The short and sweet of it is that I needed to clean the baked on soot from the bottom of my saucepans. Over the years, layers and layers of baked on soot had formed a black, enamel like coating that was resistant to cleaning. If you could have seen the bottom of my saucepans, you would have thought it was enamelware. Little did I know that its presence was contributing to the acetaldehyde flavors smell/taste in my food. So the quick takeaway is thus: clean the bottom of your pots!

    I had purchased another Trangia burner recently and was dismayed to find that it did initially solve my acetaldehyde problem. Looking at the posts here, I then tried diluting the ethanol with water at 5/10/15% to slow down the vaporization of the ethanol to allow for more complete combustion. Increasing concentrations of water did help, but the acetaldehyde was still present. Basically, I couldn’t get the concentration of water high enough to suppress acetaldehyde production and still maintain a lit burner.

    Posts on this thread had mentioned the connection between sooty pans and off tastes in relation to fuel choice. Well, I was using what I considered the “correct” fuel (for me anyway). That left the sooty pans that I had long since given up trying to clean. Since there was no actual soot rubbing off, I did not consider it a problem. Removing the soot involved soaking the bottom of the pans in a weak solution of water and cream of tartar. After the soot was removed, I boiled water using 0/5/10/12% solutions of water+ethanol. Lo and behold, the acetaldehyde smell and taste was no longer present.

    I would like to hear your theories as to what the sooty layer was doing to increase the acetaldehyde production. I have my own wild-a** guesses. First, the baked on sooty layer was a thermal insulator. By slowing down the flow of heat into the saucepan and thus the water, the sooty layer would get hotter that the aluminum behind it. Now, being basically black and hot, the sooty layer would be a more efficient thermal emitter than the aluminum. By radiating much of its heat downward, this sooty layer would enhance the vaporization of the ethanol in the burner, leading to a fuel rich environment under the saucepan. With the limited amount of oxygen in that confined space, acetaldehyde formation rates would increase. Though not very likely, it is also possible that the carbon in the sooty layer was also reacting with what little oxygen was available, further increasing the likelihood of incomplete combustion of the ethanol.

    Thank you everyone for your suggestions. I am happy beyond words to have finally resolved this issue.
     
  18. Ed Winskill

    Ed Winskill United States Subscriber

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    A most interesting thing!
     
  19. gieorgijewski

    gieorgijewski Subscriber

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    This is not my cup of .... but
    2C2H5OH + O2 → 2CH3CHO + 2H2O
    this is cathalitic reaction
    where
    palladium or salt of Cu - is needed

    try to use stainless steel burner
    to get standard

    C₂H₅OH + 3O₂ -> 2CO₂ + 3H₂O

    C₂H₅OH + 2O₂ -> 2CO + 3H₂O


    C₂H₅OH + O₂ -> 2C + 3H₂O
     
  20. Murph

    Murph United States Subscriber

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    Methanol and air over hot copper oxides will generate formaldehyde like you wouldn't believe! Used to product my own hexamine that way when it got tough to get!

    Using a aquarium pump to bubble air through methanol and the vapor mixture through a Pyrex tube filled with hot copper wool, generating formaldehyde, and the gas was passed through a aqueous ammonia solution, and there I was, hexamine!

    By switching between two flasks of methanol and two flasks of ammonia solution, the process was continuous, like a very scaled-down chemical manufacturing plant!

    Murph