[Stoves] venturi system -ratios of air and gas?
Boll, Martin Dr.
boll.bn at t-online.de
Fri Jan 8 17:52:36 CST 2016
Thanks for your helpful insights!
Let me make some very rough conclusions that I got from your helpful advice:
1. The volume of air must be far bigger than propane, methane or woodgas, to fit exactly.
2. Premixing of gas and air must _not_ be complete before begin of burning.
3. It will be difficult to predict exact ratios; even it will be difficult to predict narrow ranges of ratios.
4. But the train takes me into a complete other direction.
After reading Crispin's Sentences:
" It is likely that a propane flame is not premixed. A natural gas flame
probably is. Being pre-mixed doesn't mean it is 100% supplied, only that it is an aid-enriched gas mix that is depending on available air near the flame
to complete combustion."
The switch in my brain clicked !! :
If the mixture is complete, we will not have a usable flame, but an explosion, could be a slow-migrating one, but far of a flame we can use.
- Look for the root-vole defending videos with propane and oxygen with an USA patented gear.
- With a roof-worker burner (just with air instead of oxygen, mitigated by N2 ), - in the right ratio, you will even have an explosion for root-voles, instead of a usable flame; (-but not as powerful as necessary for that reason )
Those simple facts are basic, but they only reach in my "real"-understanding just now.
We simply would have a reaction as in the burning-chamber of an gas-motor.
- Imagine the pot on the stove, acting as a one piston engine !! :-)
( possibly an odd idea for a patented drink-shaker )
My guessing/conclusion for forming a usable flame:
- A "fat mixture", I guess/state, has to burn into air, "to complete combustion" (as Crispin says)
If the "fat" mixture" would burn into a "lean-mixture", as it does in a modern motors, we would evenly have a "pot-piston" instead of a pot, resting to boil on a stove.
Final conclusion:
My background idea, to invert in a venturi-burner-system the driving and the drawn element, will be difficult, but out of other reasons than I expected.
- I first thought, it could be difficult by venturi-effect to reach the needed ratios. And that would be the struggle-point.
But the point is, that mathematically exact-fitting mixtures make "explotions" instead of "normally-shaped" flames.
My new found angle to look to that, is certainly no re-inventing the wheel, but useful for my basic understanding.
And I smile for myself when, I guess you are smiling as well with me, - realizing, astonished somehow, that somehow a round wheel rolls, but a blocked one does not, even it is round and not edged; facts we all knew before.
Kind Regards
Martin
Am 08.01.2016 um 20:00 schrieb stoves-request at lists.bioenergylists.org:
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> 1. venturi system -ratios of air and gas? (Boll, Martin Dr.)
> 2. Re: Open House at Aprovecho Research Center (Agnes Klingshirn)
> 3. Re: venturi system -ratios of air and gas? (ajheggie at gmail.com)
> 4. Re: venturi system -ratios of air and gas? (Frans Peeters)
> 5. Re: venturi system -ratios of air and gas?
> (Crispin Pemberton-Pigott)
> 6. Re: venturi system -ratios of air and gas? (Philip Lloyd)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 8 Jan 2016 00:31:19 +0100
> From: "Boll, Martin Dr." <boll.bn at t-online.de>
> To: stoves at lists.bioenergylists.org
> Subject: [Stoves] venturi system -ratios of air and gas?
> Message-ID: <62DF55DC-9ADA-487C-94D9-A6A79D5805E8 at t-online.de>
> Content-Type: text/plain; charset=iso-8859-1
>
> A happy New Year to all stovers!
>
> In a venturi system like of a propane gas-burner the driving gas has pressure about 30 to 50 millibar.
> - What ratio have the volumes of gas and air, to make our admired blue flame, as it does in gas-flames?
> -What ratio(range) must have air and woodgas , to get the same blue flame?
>
> - I am aware different temperatures make a big difference in volume
>
> Have all a great 98% "remaining rest" of the New Year!
>
> Martin
>
> P.S.
> Simple questions have the tendency to afford complicated answers, sometimes (even often)
> they exceed the capacity of the asking person.
>
> 2nd P.S.
> Es gibt Dinge, die sind so einfach, dass man sie nicht erkl?ren kann. (MRT)
> (There are (even) things being so simple, that they cannot be explained)
>
> 3rd P.S.
> Smile is a happy solution.
>
>
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Fri, 8 Jan 2016 08:18:55 +0100
> From: "Agnes Klingshirn" <aklingshi at t-online.de>
> To: "'Discussion of biomass cooking stoves'"
> <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] Open House at Aprovecho Research Center
> Message-ID: <002f01d149e4$d629a680$827cf380$@de>
> Content-Type: text/plain; charset="utf-8"
>
> Sounds great, wish I were there! But hope, that we get a lot of the information afterwards in your reports! Enjoy the opportunity! Greetings, Agnes
>
>
>
> Von: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] Im Auftrag von Mike Hatfield
> Gesendet: Donnerstag, 7. Januar 2016 18:21
> An: Discussion of biomass cooking stoves
> Betreff: [Stoves] Open House at Aprovecho Research Center
>
>
>
> I think Paul has already said this but wanted to reinvite everyone to ARC's open house after Ethos.
>
>
>
> There will be two hour long lectures on 'Tier 4' stoves every day (Tuesday, Wednesday, Thursday). The cost is $200 if you can afford it, contact us if you can't. The two hoods will be running all day for testing. The cafeteria will be open for folks to cook (free donuts and coffee every morning) and we will provide a Welcome Dinner/Party Tuesday evening with entertainment. We will test new stoves and the intention is for everyone to leave with a thorough understanding of the whole range of new generation stoves.
>
>
>
> Wahoo!!!
>
>
>
>
> --
>
> Mike Hatfield
> Director of International Projects
>
> (541) 767-0287 (Office)
> (541) 357-9857 (cell)
> Aprovecho Research Center
> www.aprovecho.org <http://www.aprovecho.org/> (stoves)
> www.aprovecho.net (education center)
>
> Statistically, the probability of any one of us being here is so small that you'd think the mere fact of existing would keep us all in a contented dazzlement of surprise -Lewis Thomas
>
>
>
> The known is finite, the unknown infinite, intellectually we stand on an islet in the mist of an illimitable ocean of inexplicability. Our business in every generation is to reclaim a little more land - T. H. Huxley
>
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> ------------------------------
>
> Message: 3
> Date: Fri, 08 Jan 2016 10:39:06 +0000
> From: ajheggie at gmail.com
> To: Discussion of biomass cooking stoves
> <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] venturi system -ratios of air and gas?
> Message-ID: <ma3v8blhfhucr4t8jj889g8dvj11ulo31n at 4ax.com>
> Content-Type: text/plain; charset=us-ascii
>
> [Default] On Fri, 8 Jan 2016 00:31:19 +0100,"Boll, Martin Dr."
> <boll.bn at t-online.de> wrote:
>
>> A happy New Year to all stovers!
>>
>> In a venturi system like of a propane gas-burner the driving gas has pressure about 30 to 50 millibar.
>> - What ratio have the volumes of gas and air, to make our admired blue flame, as it does in gas-flames?
>
> As you thought it is a bit more complicated, the stoichiometric
> (chemically exact amounts to react for complete combustion) mass ratio
> of methane (same principle for propane but numbers are simpler) and
> oxygen is about 4:1 but as you have to allow for the other
> constituents of air, principally nitorgen, this means you actually
> have to supply about 17 kg of air for every 1 kg of gas.
>
> Volume ratio is different but can be calculated by knowing that each
> mole of gas occupies the same volume. From the mass calculation with
> molar values rounded to intergers.
>
>
> CH4+2O2+7N2=CO2+2H20+7N2
>
> So 1 volume of gas reacts with 9 volumes of air to give 10 volumes of
> combustion products at standard temperaure and pressure, of course as
> you are aware after the flame the temperature has increased to 2000C
> so the volumes are much larger.
>
> In practice a little more air is supplied to keep the flame clean.
>
>> -What ratio(range) must have air and woodgas , to get the same blue flame?
>
> The blueness is a feature of the gas and air being premixed.
>
> The stochiopmetric mass ratio for wood is about 5 parts air to 1 part
> dry wood, because wood is already partially oxidised. This relates to
> about 4.4 M3 of air to 1 kg of wood. In practice much more air is
> used, this higher need for excess air is one reason a wood flame is
> never going to get as hot as a gas flame.
>
> Who volunteers to check my workings?
>
> Andrew
>
>
>
> ------------------------------
>
> Message: 4
> Date: Fri, 8 Jan 2016 14:13:50 +0100
> From: "Frans Peeters" <peetersfrans at telenet.be>
> To: "'Discussion of biomass cooking stoves'"
> <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] venturi system -ratios of air and gas?
> Message-ID: <004d01d14a16$6af28670$40d79350$@telenet.be>
> Content-Type: text/plain; charset="us-ascii"
>
> Andrew ,
>
> You have better air 22% ? then we have ....20% means 10 vol air for 1
> mol propan .
>
> -----Oorspronkelijk bericht-----
> Van: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] Namens
> ajheggie at gmail.com
> Verzonden: vrijdag 8 januari 2016 11:39
> Aan: Discussion of biomass cooking stoves
> Onderwerp: Re: [Stoves] venturi system -ratios of air and gas?
>
> [Default] On Fri, 8 Jan 2016 00:31:19 +0100,"Boll, Martin Dr."
> <boll.bn at t-online.de> wrote:
>
>> A happy New Year to all stovers!
>>
>> In a venturi system like of a propane gas-burner the driving gas has
> pressure about 30 to 50 millibar.
>> - What ratio have the volumes of gas and air, to make our admired blue
> flame, as it does in gas-flames?
>
> As you thought it is a bit more complicated, the stoichiometric (chemically
> exact amounts to react for complete combustion) mass ratio of methane (same
> principle for propane but numbers are simpler) and oxygen is about 4:1 but
> as you have to allow for the other constituents of air, principally
> nitorgen, this means you actually have to supply about 17 kg of air for
> every 1 kg of gas.
>
> Volume ratio is different but can be calculated by knowing that each mole
> of gas occupies the same volume. From the mass calculation with molar values
> rounded to intergers.
>
>
> CH4+2O2+7N2=CO2+2H20+7N2
>
> So 1 volume of gas reacts with 9 volumes of air to give 10 volumes of
> combustion products at standard temperaure and pressure, of course as you
> are aware after the flame the temperature has increased to 2000C so the
> volumes are much larger.
>
> In practice a little more air is supplied to keep the flame clean.
>
>> -What ratio(range) must have air and woodgas , to get the same blue flame?
>
> The blueness is a feature of the gas and air being premixed.
>
> The stochiopmetric mass ratio for wood is about 5 parts air to 1 part dry
> wood, because wood is already partially oxidised. This relates to about 4.4
> M3 of air to 1 kg of wood. In practice much more air is used, this higher
> need for excess air is one reason a wood flame is never going to get as hot
> as a gas flame.
>
> Who volunteers to check my workings?
>
> Andrew
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
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>
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> http://stoves.bioenergylists.org/
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Fri, 8 Jan 2016 10:25:39 -0500
> From: Crispin Pemberton-Pigott <crispinpigott at outlook.com>
> To: "'Discussion of biomass cooking stoves'"
> <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] venturi system -ratios of air and gas?
> Message-ID: <COL401-EAS20034B36D5E3323E3FC3169B1F60 at phx.gbl>
> Content-Type: text/plain; charset="us-ascii"
>
> Dear Investigators
>
> What is the analysis of the propane that you consider 'typical'?
>
> If you can suggest a C, H, O % by mass, I can tell you the volume based on
> whatever excess air requirement you think is necessary.
>
> It is likely that a propane flame is not premixed. A natural gas flame
> probably is. Being pre-mixed doesn't mean it is 100% supplied, only that it
> is an aid-enriched gas mix that is depending on available air near the flame
> to complete combustion.
>
> I have some LPG formulations kicking around from India, South African and
> Nigeria. More important for the calculation below, what do you think the
> mass factions are?
>
> Regards
> Crispin
>
> -----Original Message-----
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
> Frans Peeters
> Sent: Friday, January 08, 2016 08:14
> To: 'Discussion of biomass cooking stoves' <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] venturi system -ratios of air and gas?
>
> Andrew ,
>
> You have better air 22% ? then we have ....20% means 10 vol air for 1
> mol propan .
>
> -----Oorspronkelijk bericht-----
> Van: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] Namens
> ajheggie at gmail.com
> Verzonden: vrijdag 8 januari 2016 11:39
> Aan: Discussion of biomass cooking stoves
> Onderwerp: Re: [Stoves] venturi system -ratios of air and gas?
>
> [Default] On Fri, 8 Jan 2016 00:31:19 +0100,"Boll, Martin Dr."
> <boll.bn at t-online.de> wrote:
>
>> A happy New Year to all stovers!
>>
>> In a venturi system like of a propane gas-burner the driving gas has
> pressure about 30 to 50 millibar.
>> - What ratio have the volumes of gas and air, to make our admired blue
> flame, as it does in gas-flames?
>
> As you thought it is a bit more complicated, the stoichiometric (chemically
> exact amounts to react for complete combustion) mass ratio of methane (same
> principle for propane but numbers are simpler) and oxygen is about 4:1 but
> as you have to allow for the other constituents of air, principally
> nitorgen, this means you actually have to supply about 17 kg of air for
> every 1 kg of gas.
>
>
>
>
> ------------------------------
>
> Message: 6
> Date: Fri, 8 Jan 2016 17:44:08 +0200
> From: "Philip Lloyd" <plloyd at mweb.co.za>
> To: "'Discussion of biomass cooking stoves'"
> <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] venturi system -ratios of air and gas?
> Message-ID: <008601d14a2b$700a08d0$501e1a70$@co.za>
> Content-Type: text/plain; charset="us-ascii"
>
> Pure propane is 81.8% C, 11.2% H by mass - no O. Most commercial propane has
> a bit of ethane and a bit of butane in it, but not enough to alter this
> ratio drastically.
>
> Philip
>
> -----Original Message-----
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
> Crispin Pemberton-Pigott
> Sent: 08 January 2016 05:26
> To: 'Discussion of biomass cooking stoves'
> Subject: Re: [Stoves] venturi system -ratios of air and gas?
>
> Dear Investigators
>
> What is the analysis of the propane that you consider 'typical'?
>
> If you can suggest a C, H, O % by mass, I can tell you the volume based on
> whatever excess air requirement you think is necessary.
>
> It is likely that a propane flame is not premixed. A natural gas flame
> probably is. Being pre-mixed doesn't mean it is 100% supplied, only that it
> is an aid-enriched gas mix that is depending on available air near the flame
> to complete combustion.
>
> I have some LPG formulations kicking around from India, South African and
> Nigeria. More important for the calculation below, what do you think the
> mass factions are?
>
> Regards
> Crispin
>
> -----Original Message-----
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
> Frans Peeters
> Sent: Friday, January 08, 2016 08:14
> To: 'Discussion of biomass cooking stoves' <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] venturi system -ratios of air and gas?
>
> Andrew ,
>
> You have better air 22% ? then we have ....20% means 10 vol air for 1
> mol propan .
>
> -----Oorspronkelijk bericht-----
> Van: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] Namens
> ajheggie at gmail.com
> Verzonden: vrijdag 8 januari 2016 11:39
> Aan: Discussion of biomass cooking stoves
> Onderwerp: Re: [Stoves] venturi system -ratios of air and gas?
>
> [Default] On Fri, 8 Jan 2016 00:31:19 +0100,"Boll, Martin Dr."
> <boll.bn at t-online.de> wrote:
>
>> A happy New Year to all stovers!
>>
>> In a venturi system like of a propane gas-burner the driving gas has
> pressure about 30 to 50 millibar.
>> - What ratio have the volumes of gas and air, to make our admired blue
> flame, as it does in gas-flames?
>
> As you thought it is a bit more complicated, the stoichiometric (chemically
> exact amounts to react for complete combustion) mass ratio of methane (same
> principle for propane but numbers are simpler) and oxygen is about 4:1 but
> as you have to allow for the other constituents of air, principally
> nitorgen, this means you actually have to supply about 17 kg of air for
> every 1 kg of gas.
>
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
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>
> to UNSUBSCRIBE or Change your List Settings use the web page
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>
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> http://stoves.bioenergylists.org/
>
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>
>
>
> ------------------------------
>
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>
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