What % reduction in gas flow results from changing to LPG?

[pkc111]

TL;DR Summary

My Rubens Tube is running on natural gas and I am having some problems that maybe related to high gas speed in the tube. I am hoping that changing to LPG may reduce this gas speed problem a lot.

There are 70 jets of 1/16" diameter along the tube and I neeed to create flames 1" high.
I know the calorific value of natural gas is much less than LPG (39 MJ/m3 Vs 93 MJ/m3) . I am not sure what assumptions to make from there in order to compare the predicted natural gas to the LPG volume rate consumption? Ie will a 1 inch flame of both gases consume the same m3/h or does it work that both 1 inch flames of each gas type produce the same MJ/h? I have read that the flame temperature of both gases is around 3550F if that helps?
Thanks

 

[Navin A S]

The flame temperature of both gases will be the same, but the volume rate consumption will be different. Natural gas has a lower calorific value than LPG, so it will generally require more m3/h to produce the same amount of heat. You can calculate the volume rate consumption of each gas by dividing the calorific value (in MJ/m3) by the flame temperature (in Kelvin). For example, for natural gas, you would divide 39 MJ/m3 by 5810 Kelvin, which would give you 0.0067 m3/h. For LPG you would divide 93 MJ/m3 by 5810 Kelvin, which would give you 0.0159 m3/h. So in this case, the LPG flame would require more than double the volume rate consumption of natural gas to produce the same amount of heat.