Firetube Questions

[tcs.ufba]

I’m projecting a heat treater as shown below.
In my study I’m using a 30°API oil with an inlet flow rate of 3800bbl/d* 1170bbl/d water flow rate and 0.8MMscfd gas flow rate* the operating temperature is 120°F and field temperature 68°F. The fuel used in the firetube is natural gas and the Inferior calorific value is 47MJ/kg. The capacity for the firetube in our project needs to be 1*75MMBTU/hr and we would like a firetube with 24’’ diameter.

Data:
Vessel Size 8’x25’: Diameter 8 ft x Length 25 ft
Inferior calorific value: 1*75MMBTU/hr
Firetube diamater: 24 inches
Oil: 30°API
Field ( ambient) temperature(inlet): 68°F
Vessel Operating temperature: 120°F
Oil flow rate: 3*800bbl/d (barrels per day)
Water flow rate: 1170bbl/d
Gas flow rate: 0.8MMscfd
Inferioc caloric value: 47MJ/kg


i)Which would be the firetube length ? How do I calculate this?
ii)About the convection section of the firetube* do you include a firetube turbulator? If yes* how do you evaluate the influence of this in the firetube length?
iii)Which would be the firetube flux (Q/A)?
iv)If I use a forced draft blower the firetube flux(Q/A) would increase ? If yes* what is the ideal air flow rate forced by the blower?
v)What would be the operation pressure inside the firetube?

[chunlin]

You may use the book as guideline to do the calc- Oilfield Surface Facilities Handbook.