Example 10:

A size of a cylindrical furnace for layer combustion is D=1m and H=1 m . A composition of combustion products is: 14% CO2 , 4% H2 O and 82% N2 and O2. A theoretical temperautre is: TFo = 1900 K. Evaluate a temperature of compustion products at the furnace exit. The fuel flow is B = 0,035 kg/s and the quantity VRW = 4,5 Nm3 /kg and specific heat of combustion products for 1500 K is cp = 1,5 kJ/Nm3, a factor for the given fuel  M=0,534:

Solution:

A following direct procedure is common in boiler engineering to estimate a furnace exit temperature:


p=0,14+0,04 = 0,18 b

eg=1-e-kg ps=0,1614
 For a given furnace it is:
y =1 and x = 0,6
A radiation coefficient of the furnace is:
A temperature ratio using Boltzmann number is:
 


TF2= 1305 K
Since this temperature differs from the guessed one, it is necessary succesively to repeat the calculation until the difference falls within small limits. It is very convenient to use a computer program for that purpose.
 
  Program Furn.for, Furn.exe
Data        Input, Output