Quantity Air Assistance for smokeless flare ***calculation

[Saver2008]

Hi everybody!

I have the following situation:
I have calculated a flare stack for 20 MMPCSD and I need to add it an AIR ASSISTANCE for being smokeless, and the want it for 40% of maximum capacity (20 MMPCSD) So I have made the following:
Other data: 7 psig at flare stack base
35 celcius of temperature of gas
Mainly composition is 60% CH4

1 ft3 gas (methane) ------ 9.53 ft3 air
If 20 MMPCSD = 20,000,000 ft3/day ===> 13,888.80 ft3/min
So for obtaining the total of air
13,888.80 ft3/min x 9.53 ft3 air = 132,360.26 ft3/min
Now I took 40% from last value
132,360.26 ft3/min x 0.4 = 52,944.10 ft3/min
Now, I know that air has 20% of O2 so
52,944.10 ft3/min x 0.2 = 10,588.82 ft3/min

So the requiring amount of air for 20 MMPCSD at 40% is
10,588.82 ft3/min, but when I choose the ventilator is so big due to ft3/min obtained....am I wrong??

Please help me with this

Thanks!!!
Roland

 

[TD2K]

Air assist flares do use a lot of air. I have some data on an air assist flare I installed, it's a lot heavier gas but it would give you an idea. Have to dig it out of work tomorrow.