What is Max. Air flow in combutstion air nozzle?

[hjmin]

Hello all,

we have a burner which use a napha for fuel and it have combustion air nozzle in burner.

Combustion air flow 380 m3/min @ ATM
Combustion air fan discharge pressure : 500 mmAQ
Combustion air nozzel area : 120mm X 25mm


I would like to know what max. volume can go through that nozzle?
because we have enough fan capacity, but we can not increase to that air flow. so now we think it bottleneck is combustion air nozzel.
please can you calculate Max. vol. flow in this nozzle.

thank you

 

[athomas236]

I think may be you should talk to the burner supplier, they usually, but not always, know their burners best.

athomas236

 

[hjmin]

Thank you. unforntunaly our burner is very older one. therfore we can not contacted burner vendor.
how can I solve this matter?

 

[hjmin]

For this matter, we operated combustion air fan at 150 degree C, but that flow can not increased.
So we think that bottle neck is combustion air nozzle....

 

[25362]

Although not exactly the subject in hand,
a 6% by vol moisture in air, may cancel
a 5-10% xs air factor resulting in incomplete
burning.

 

[AbbyNormal]

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[AbbyNormal]

nozzles should be similar, sorry it is not in SI units

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[Oxidation]

Could be that your fan does not have enough capacity! Even though you think it has, you need 9.55 volumes of air at STP for every volume of gas (CH4) basis plus 3% extra to ensure complete combustion. This rule also applies to liquid fuels. Naptha should burn well as long as it atomised before combustion.

The burner you are using, you say it has a dimension of 120x25mm, this is the throat area of the burner at the furnace wall. The only restriction for any burner is how much air you can get through it for any given amount of fuel. Obviously if you put more fuel & air in you increase the overall heat release & the flame length.

So, if you have enough air capacity in your fan as you say it should have no problem pushing the air into the furnace.
Your fan may be sized to work against a maximum DP & I would think you are off its curve.

I suggest you crank up your fan & measure the DP between the point at which air leaves the fan & enters the burner & the pressure in side the furnace/combustion chamber. Then check it against the original fan curve.

 

[avimech]

Need some help. I'm looking to convert a large oven from a direct fired to a modulating gas burner. I'm looking for anyone who can direct me to a modulating gas burner package i.e (blower and gas valve) unit and what controller that will fit the package controlling from 0-350 deg f. It needs to be up to 120k btu/h. I'm no expert in this field. I'm more of and electronics tech. Any assistance or direction is greatly appreciated.

 

[rthiyagu00]

Dear Mr. hjmin,

The Maximum air flow that can flow through the nozzle depends on the Head/pressure available at the nozzle (i.e) 500mmAQ - Pressur Loss in the connecting ducts/pipes between Fan and the nozzle.

Air Flow = Constant*Area(120mm*25mm)*Sq.root of H Head/pressure available at the nozzle

R.Thiyagarajan.

 

[Combustor1]

Avimech - I suggest you try Maxon for an Oven-Pak Burner and you should start your own thread.


Hjmin -

A fan has a certain static pressure that it is designed for if you are firing in to a smaller area - your pressure drop could be high for the air you are trying to push through - check for any manufactures name model No on the fan and try contacting them. The other thing you could do is do a Pitot tube tranverse in the duct (if you have one) - Dwyer sells Pitot tubes.

If you are burning Naphtha then your heating value and air requirements might be less than Natural gas since Naphtha is 15,000 Btu/lb Nat gas is 21,800 Btu/lb. Then you have to look at the characteristics of your buner / furnace or what ever you have.

Don't blow yourself up - suggest you call in a professional.

Combustor

 

[chicopee]

hjmin-Make sure that your combustion chamber is big enough to sustain the increase in heat output of the burner.Also check the namplate on the burner for the range in firing rate which may give you a clue as to what is realistic.