Author Topic: Natural gas/air mixture for burner  (Read 345 times)

Offline trapae

  • Brewer
  • ****
  • Posts: 257
    • View Profile
Natural gas/air mixture for burner
« on: October 10, 2018, 03:18:34 AM »
I have a couple natural gas burners and just upgraded to a brewstand. Never really paid much attention to my flame untill I started reading more about carbon monoxide and flame height and color. Turns out to get a good boil I am needing to turn it up high enough to get a decent amount of yellow on my flame. Been doing some reading and it sounds like the more air the better to mix with natural gas for good blue flame.
...... So the question is, can I just take off the front air intake adjuster completely to get more air being sucked into the flame for a better blue fire flame?
Thanks
I am a great believer in luck, and I find the harder I work, the more I have of it.

Offline RC

  • Assistant Brewer
  • ***
  • Posts: 136
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #1 on: October 10, 2018, 04:29:33 PM »
Yes. But you only need enough air to supply the stoichiometrically required amount of oxygen. At this point you'll get the strongest, bluest flame possible for your burner. Beyond this, you're just diluting the gas with air and reducing the BTU output.

Offline KellerBrauer

  • Assistant Brewer
  • ***
  • Posts: 166
  • Bottoms Up!
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #2 on: October 11, 2018, 01:09:10 PM »
Any yellow in a natural gas flame is a very bad thing and you need to avoid it at all costs.  Yellow in the flame indicates carbon and is the result of low oxygen.  Carbon in a flame is a clear indication the flame is creating carbon monoxide.

Further, I would NOT recommend removing the air intake vains of your burner.  It is there for a reason.  The manufacturer would not have included it if it were not necessary and could be discarded.  I have offered several posts on this subject and in these posts I have stated that achieving the perfect flame is all about the perfect balance of gas pressure, gas flow and oxygen mixture.

I’m not familiar with a Brewstand, but after reading your post, it seems to me like you are trying to force your burner to do more than it was designed to do and THAT is the perfect recipe for disaster.
All good things come to those who show patients and perseverance while maintaining a positive and progressive attitude. :-)

Offline MNWayne

  • Cellarman
  • **
  • Posts: 86
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #3 on: October 11, 2018, 02:14:58 PM »
Yellow flames =  spider webs.  Whenever I get yellow flames on my propane burner, or BBQ grill, it means it's time to clean out the spider webs. The gas/air mixture usually travels down a tube leading to the burners. This tube seems to be a favorite spot for spider webs. Just a few is all it takes. Chase them out with a brush, pipecleaner, or rag. It never seems like it should be enough to make a difference, but it does. Blue flames should return, nice hot burn, quick boils, no black pots.

Offline trapae

  • Brewer
  • ****
  • Posts: 257
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #4 on: October 11, 2018, 02:19:26 PM »
 It is a Blichman burner.   I read the most burners are made for propane. I do have a natural gas valve on it. I have read several places that most of these burners, When converted to natural gas, need more oxygen to get a larger blue flame. That’s why I was asking if taking off the front air intake would provide a better oxygen to gas ratio for natural gas.
I am a great believer in luck, and I find the harder I work, the more I have of it.

Offline Slowbrew

  • Brewmaster General
  • *******
  • Posts: 2432
  • The Slowly Losing IT Brewery in Urbandale, IA
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #5 on: October 11, 2018, 09:28:26 PM »
It is a Blichman burner.   I read the most burners are made for propane. I do have a natural gas valve on it. I have read several places that most of these burners, When converted to natural gas, need more oxygen to get a larger blue flame. That’s why I was asking if taking off the front air intake would provide a better oxygen to gas ratio for natural gas.

Probably a dumb question but when you converted it to Natural Gas did you change the orifice too?  If not your flow will be all messed up.

Paul
Where the heck are we going?  And what's with this hand basket?

Offline trapae

  • Brewer
  • ****
  • Posts: 257
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #6 on: October 11, 2018, 10:28:37 PM »
 Yes I did change the valve orifice over to the Blichman recommended natural gas valve. Although when I gave the burner to the company that made the Brewstand, they put in their own natural gas valve. I should probably take it off and compare it to the one I had been using since I feel like it was working better prior.
I am a great believer in luck, and I find the harder I work, the more I have of it.

Offline KellerBrauer

  • Assistant Brewer
  • ***
  • Posts: 166
  • Bottoms Up!
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #7 on: October 11, 2018, 10:28:57 PM »
It is a Blichman burner.   I read the most burners are made for propane. I do have a natural gas valve on it. I have read several places that most of these burners, When converted to natural gas, need more oxygen to get a larger blue flame. That’s why I was asking if taking off the front air intake would provide a better oxygen to gas ratio for natural gas.

Probably a dumb question but when you converted it to Natural Gas did you change the orifice too?  If not your flow will be all messed up.

Paul

+1 Slowbrew.

Propane is higher in pressure than natural gas.  Therefore, when converting a propane burner to natural gas, the burner oriface needs to be increased to a larger diameter to allow more fuel to flow.  So, if you are using a valve intended for natural gas and it’s feeding your burner through an orafice that’s too small, you will not be able to gain enough oxygen through the air intake damper to satisfy the fuel supply.

The intake damper(s) allows air to flow through a dynamic called a Venturi; the greater the flow of fuel, equals the greater the flow of air.  The flow of fuel and the quantity of air introduced through the Venturi was designed for the higher pressure propane and will not work with natural gas without modifications because the volocity of fuel through the orafice simply isn’t there.  I recommend contacting a professional HVAC mechanic for assistance or see if the manufacturer has a conversion kit for the burner.

Yes, spider webs will also cause a reduced fuel/air mixture.  However, I don’t believe that’s the case here.
All good things come to those who show patients and perseverance while maintaining a positive and progressive attitude. :-)

Offline trapae

  • Brewer
  • ****
  • Posts: 257
    • View Profile
Re: Natural gas/air mixture for burner
« Reply #8 on: October 17, 2018, 02:33:01 AM »
 Just an update. I realized that the heat shield on the entire front half of the burner wasn’t allowing good airflow around the kettle. I Elevated the pot with half-inch stainless steel pieces and BAM, a perfect half inch blue flame without any yellow.....So not only do you need The right gas/air mix coming into the burner, but also at the flame level.
I am a great believer in luck, and I find the harder I work, the more I have of it.