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I am trying to calculate the dimesnions of a natural gas burner for a hospital. The burner will be heating water. I have calculated the thermal duty that needs to be produced and the water mass flow, but I haven't found equations that will allow me to calcuate any characteristics of the final construction.

My approach so far is treating the burner as if it was a gas CSTR. The problem is that I havent really found any literature doing the same thing, so I doubt that this apporach is right.

Does anyone know of the relative literature for my problem or has to suggest any tactic I should use?

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    $\begingroup$ I think you guesstimate the total BTU you want and ask for bids from vendors. They will likely calculate BTU requirements on their own. I know from refineries there are dramatically different type of burners when you get to industrial applications. $\endgroup$ – blacksmith37 Dec 12 '20 at 22:27
  • $\begingroup$ Thanks for your comment @blacksmith37! However my goal is go calculate the size myself because I need to present the ideal burner. Choosing a burner from the market is a step afterwards. $\endgroup$ – Charalamm Dec 12 '20 at 22:41
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    $\begingroup$ I would have thought the "ideal burner" is the number of BTUs you need, given the likely efficiency of the heat exchanger. Obviously a heat exchanger that is 40% efficient will need twice as much heat input as one that is 80% efficient. I really don't see what a CSTR has to do with the calculation. $\endgroup$ – alephzero Dec 13 '20 at 3:34
  • $\begingroup$ Burner and boiler design ist also determined by teat transfer and managing the flame temeprature. Just talk to vendors already. $\endgroup$ – mart Dec 13 '20 at 20:30
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You cant treat it as CSTR, not even for guestimate. Gas reactions are much more dependent on mixing. Imagine a candle fire, it gives 1 MW/m3, and imagine 747 Boeing engine, that gives about 1000 MW/m3, if we calculate only the fire chamber. Three orders of magnitude of difference, and you can have any value inbetween.

Best what you can do is to take some device with similar properties of flame, like fuel and pressure available, amount of air available, and take that device's volume needed for a flame. And hope that scaled up version will behave similarly. So if you want a gas as a source, find some gas burner, and check how much power it gives per volume of flame. Modern burners likely can be much better than just an open flame, with swirls to assist the mixing. Small gas burners often use catalyst that you likely wont be able to afford for a big burner, keep this in mind too.

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