Galley alcohol, gas, diesel and induction cookers/ovens

  • 05 Apr 2017 07:15
    Reply # 4712951 on 1195343

    Here's an interesting DESCA 2 burner sprituskocher in good condition. It might not be a good boat's cooker as-is, but would be an intro into the world of cooking on an alcohol stove.

  • 05 Apr 2017 06:57
    Reply # 4712920 on 1195343

    Other names to look out for are TURM , NORMA and DESCA 

    These examples are old, and may or may not be worth taking the burner and tank and incorporating them into a seagoing body.

  • 05 Apr 2017 05:12
    Reply # 4712817 on 1195343
    Deleted user

    I learned a new word tonight, "spirituskocher".  Apparently the Germans have been making Maxie-type stoves for some time.  Searching spirituskocher on ebay.de yielded results for quite a few stoves that work like a Maxie, even a nice stainless unit by a company called Enders.  Most of these you would just take the burner and maybe the tank, and then build yourself a new enclosure.

    I also found a new stove available on Amazon as well as some camping stores, it is called a Spirituskocher Salsa.  The burner is similar to the Maxie, but it has a nice brass appearance to it.  Maybe it would be longer lived than the Maxie burner?

    Here is a link to a review of the Salsa stove that gives some nice detailed pics of the burner.  Here is a video of the same stove for those who are wondering how these stoves work or those who would like to see the details of the inside of the burner (look around 6:45 in the video).

    I'm not sure how long-lived the framework of the Salsa would be, but powder coated steel should last long enough to figure out if you want to build a nice stainless body for the burners.   For 65 Euro for the one burner model (105 Euro for the two burner) maybe someone is interested in the experiment. 

    Last modified: 05 Apr 2017 05:22 | Deleted user
  • 04 Apr 2017 21:38
    Reply # 4712140 on 1195343
  • 04 Apr 2017 21:27
    Reply # 4712057 on 4712011
    Vlad Sokolsky wrote:

    David,

    Could you please post a detailed sketch of Maxie burner with the all possible dimensions.    

    Sorry, I won't be able to do this for more than a week.
  • 04 Apr 2017 20:56
    Reply # 4712011 on 1195343
    Deleted user

    David,

    Could you please post a detailed sketch of Maxie burner with the all possible dimensions.    

    Last modified: 04 Apr 2017 20:57 | Deleted user
  • 04 Apr 2017 17:24
    Reply # 4711755 on 1195343
    Deleted user

    Regarding the Maxie stove's availability, here's the response I got from Whitworths when I checked yesterday if they'd ship to the US:

    *************** 

    Love to help but we can't even get stock of these stoves ourselves!

    It's a small shop business that makes them and supply of complete stoves and spare parts is woeful - he apparently has a large contract for the Australian Army and that consumes his time and energy, humble retailers like ourselves rate a very distant last.

    Our current order for new stoves has been in for 9 months and still no sign of delivery .... but we live in hope.
     

    **************

     

  • 04 Apr 2017 16:12
    Reply # 4711499 on 1195343

    Darren,

    The Maxie would literally sometimes blow itself out when using methanol - the mixture was just on the edge of being too lean to burn.

    It's true that there will be a delayed action due to placing the valve further upstream, but the situation is actually a bit better than the Coleman gas burning camping stoves, where the valve is at the bottle and the delivery tube is quite long. Here, when you shut the valve, the flame instantly reduces to near-nothing, but then takes a minute to go out completely. This may be a good thing, as I often shut off the valve by mistake when I am aiming for a simmering heat. I would propose to keep the length of tube downstream of the valve short, and would propose to reduce its volume by placing one tube inside of another so that the bore diameter is minimal. Also, I would expect the tube often to get hot enough to vaporise the fuel back as far as the valve.

  • 04 Apr 2017 15:31
    Reply # 4711419 on 1195343
    Deleted user

    Interesting as usual David.  I have two thoughts:

    Your problems with Methanol as fuel might also have been related to the heat content of the fuel source.  Methanol only has about 75% of the energy density (calorific value) of ethanol.  I think this is enough to turn a workable stove into one that is not.

    If I've interpreted you diagrams and my Maxie correctly.  You are going to be regulating liquid fuel, while the Maxie places the valve after the vaporization tube.  I wonder if this might create issues for regulating the flame, particularly at low settings?

  • 04 Apr 2017 13:29
    Reply # 4711208 on 1195343

    As I see it, Annie, the problem of designing a good galley stove breaks down into four parts:

    Choice of fuel. Methane (natural gas) is out because it cannot compressed into a liquid and transported in convenient tanks. All the other hydrocarbons in the "alkane" series (propane, butane onwards evaporate into gases that are heavier than air, something that is tolerable in a house, or when camping, but not aboard. The lighter ones, Coleman fuel/white gas/panel wipe/naphtha, evaporate very fast, and so I reluctantly discard them for use aboard. Similarly petrol/gasoline is not safe enough for use in a cabin. It's only when we reach kerosene in the series that the rate of evaporation becomes acceptably low for safety, and then of course that means that we have to do more work to get it into gaseous form for use. The alcohols, methanol and ethanol, still produce heavier than air vapours, but they evaporate relatively slowly, the % concentration of vapour in air that has to be reached before they will burn is higher than the alkanes and when they do ignite, they burn but don't explode. It seems to me that it's a no-brainer to cook using alcohol. 
    explosive-concentration-limits
    The burner. Making a burner to use alcohol is a matter of getting the fuel/air ratio right. Methanol and ethanol both need less air than the alkanes, but methanol needs air less than ethanol. So a burner has to specifically designed for each -
    Fuel Ratio by mass [6] Ratio by volume [7] Percent fuel by mass
    Gasoline 14.7 : 1 6.8%
    Natural gas 17.2 : 1 9.7  : 1 5.8%
    Propane (LP) 15.67 : 1 23.9 : 1 6.45%
    Ethanol 9 : 1 11.1%
    Methanol 6.47 : 1 15.6%
    n-Butanol 11.2 : 1 8.2%
    Hydrogen 34.3 : 1 2.39 : 1 2.9%
    Diesel 14.5 : 1 6.8%
    Methane 17.19 : 1 9.52 : 1 5.5%

    This will explain why I found the Maxie burner to be unsuitable for use with the methanol that is available in Canada - it was getting too much air. It may also have a bearing on the way that the Maxie burner disintegrates - too much air produces an "oxidising" flame, which is trying to convert the metal of the burner into oxides. Less air, and a "reducing" flame, might give a longer burner life.

    The fuel delivery. Gravity is reliable, but variable. A gravity-fed alcohol burner must not have too much or too little head of pressure, and oscillations, or pulsing of the fuel supply, can be a problem. A pressurised tank also is not ideal. This is where a lift pump comes in, as it can be made to deliver a constant flow or constant pressure, or both. I don't think the use of a pump should be discounted. A peristaltic pump, drawing from a low level tank, may not need a valve downstream of it. 

    Safety. Vapours in the bilge due to spilt fuel are the main hazard to be guarded against. Apart from spillages during refuelling, there are issues with leaks from fuel lines and valves. A gravity tank is not failsafe, and neither is a pressurised tank. Unless a low level tank itself leaks, it is more failsafe than a gravity or pressurised tank: if the fuel line or valvework fails, there is less possibility of major leakage (assuming that if the pump is in operation, then you are actually cooking and would be aware of any malfunction causing fuel to be pumped out through a leak). Again, a lift pump should not be discounted.

    For the engineers amongst us, here are two sketches of different approaches that I want to try. The first uses the same geometry as the Maxie burner,the second is a pot burner/perforated chimney burner.



     
    Last modified: 04 Apr 2017 13:40 | Anonymous member
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