Fired Heater Efficiency Calculation

Hi,

I used the data historian to trend some data regarding one of the fired heaters we have on site to calculate the heater efficiency. Basically trying to calculate how much of the heat supplied into the heater is utilized to heat up the hot oil. This is an old furnace. The fired heater burns natural gas (92 mol% C1) to heat up Hot Oil that is circulated to the different users (distillation tower reboilers, heat exchangers...etc). 

Data trended from the historian is (daily average for 2019)

1. Hot Oil Flow

2. Hot Oil Tin, Tout

3. Fuel Gas Flow

Data calculated from the trend data

1. Delta T

2. Cp Oil at Taverage

3. Qin by Fuel Gas (39 GJ / 1000 m3)

4. Qout calculated using m x Cp x delta T for oil

The min, average and max efficiencies are 63%, 81% and 92% respectively. Please note that the 92% only happened once. I am a bit suspicious cause I am not sure if the average efficiency is high or normal hence why I am reaching out. Is there literature that talks about average efficiency of direct fired heaters?

I have also calculated the efficiency using the fuel gas analysis and stack temperature (It's a procedural article in Hydrocarbon Processing) and the calculated efficiency is 83.6% not far at all from what the actual 2019 data. 

Appreciate your feedback. I have attached the article for your reference

Thanks

Sherif

Hi,

Other documents attached to support your work.

Enjoy the reading .

Breizh

Thank you very much breizh. Sorry for this very late reply.

Hope you are well and safe in these unusual times