How to estimate Natural Gas Fuel flow rate

[Vivaldi M. Smith]

I am trying to calculate the required Natural Fuel Gas Flow rate that I will need to increase my Hot Oil Temperature from 80 to 450 F.

 

[LittleInch]

Then you need to know how much oil or a flow rate and if it's a volume, how long a period do you want?

Then calculate the energy needed and use day 85% efficiency and then divide by the CV of your gas.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Vivaldi M. Smith]

flow rate 2000 gallons per minute . What would the formula be?

 

[LittleInch]

First work out your mass flow rate.

The find the heat capacity of your particular oil over the range of temperature.

This gives you your heat required over what ever time step you choose - second, minute, hour, day

Then apply some sort of efficiency for your fired heater - maybe 80-85%? which gives you total heat from your gas,

Then divide this number by the calorific Value (CV) of your "gas".

Or ask a VENDOR to do it all for you.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

Good Luck LittleInch ...

You are in a "gimme tha formula" situation here ...

MJCronin
Sr. Process Engineer

 

[pierreick]

Hi,
Just a heat balance to perform but you need info about hot oil , Flow rate ( mass ) , heat capacity : Q = Mass Hot oil *Cp Hot oil *delta T = Mass natural gas * Heat value .Heat value should be sourced from your vendor and should appear on your monthly bill .

Pierre

 

[georgeverghese]

Thermal eff of the heater would be about 0.8 with economiser in the stack, or about 0.6 without economiser.
Also, use the lower heating value of the natural gas (LHV) and not the HHV (higher heating value).

 

[pierreick]

Hi,
To add to my previous reply consider the doc attached related to efficiency of furnace .
Good reminder from George
Good luck
Pierre

 

[Vivaldi M. Smith]

Thank you guys, much appreciated.

 

[LittleInch]

So what's your answer?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

Are you sure T1 is 80degF? Most recirculating hot oil loops would have T1 much higher.

 

[Vivaldi M. Smith]

I used the Hot Oil Q(Heat) I was able to find it, and that Qi equated to the Mass flow rate I was looking for and divde over the NHV of my natural gas. And solved!!

 

[LittleInch]

Don't forget you need to allow for the efficiency of the heater. Depending on your design this could be anywhere from ~60% to 90% efficiency. Makes a big difference.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.