1. Thermodynamic Design of a Fire-Tube
Steam Boiler
Prepared for:
Professor Kamran Shavezipur
Prepared by:
(Team 16)
John Walter
Austen Kennedy
Muhammad Shuhaimi
December 11th
, 2014

2. 2
Table of Contents
Introduction ..................................................................................................................................................3
Design Analysis and Calculations……………………………………………………………………………………………………………..4
Design Outcome……………………………………………………………………………………………………………………………………...6
References …………………………………………………………………………………………………………………………………………… .8

3. 3
Introduction:
The body of the boiler is usually the pressure vessel and contains the fluid. The fluid is normally
the water which will circulate for heating purposes and sometimes is converted to steam for
process use. The horizontal fire tube boiler has three passes. The first pass consists of furnace
while both of the second and third passes consist of tubes. While the fire tube boiler operates,
only the second and third passes are considered for the heat transfer process.
The advantages of the fire tube boiler are the cost is inexpensive, easy to clean, compact in size,
easy to replace tubes, and well suited for space heating and industrial process applications. The
disadvantages of the fire tube boiler are not suitable for high pressure applications and it has
limitation for high capacity steam generation.
This is the list of the main components in the fire tube boiler:
o Boiler shell is the outer component in a cylindrical shape that covers the pressure vessel.
o Burner is located in the vertical walls of the furnace and it brings fuel and air into the
furnace at the desired velocities, turbulence and concentration.
o Furnace is the enclosed space where the combustion takes place.
o Drain is the valve connection that removes all the water from the pressure parts.
o Feed Pump supplies water to the boiler
o Safety valve is a spring loaded valve that automatically opens when pressure attains the
valve setting. It is used to prevent excessive pressure from building up in the boiler.
o Steam separator removes the entrained water from steam
o Firebox absorbs radiant heat from the fire.
o Accumulator stores the heat of steam to be used during late period and at lower pressure.
o Insulation is made from a material of low thermal conductivity and is sued to reduce
heat losses.
o Safety shut-off valve is electrically operated to automatically shut off fuel when de-
energized.
o Circulator is used to pass steam or water between upper boiler drum which is usually
located where the heat absorption is low.
o Strainer is a filter that is used to retain solid particles allowing a liquid to get pass.
o Breeching transports the product for the production between parts of the generating unit.

4. 4
Design Analysis and Calculations:
Temperature Distribution
Tw=180 degC (Given value for water)
Heat Transfer within the Steam Boiler
To find both Q values, the equation for Qin is used. After the Qin is solved, different amounts that each
Q2 and Q3 contribute to the Qin are tested in the excel file. The Q2 and Q3 values that are used are the
ones that allow the areas A2 and A3 to be relatively close to each other.
̇
hg at 10 bar is used because the given pressure was 10 bar for within the tube. hf at 21 degC is used
because this is around what the temperature of water would be outside of the tube before it enters.
̇ ( )
After testing different percentages in the excel document, the best ones to use were 72% for Q2 and
28% for Q3:

5. 5
Area for A2 and A3 are solved for using Q2 and Q3 values and Q/A values:
Volume Ratio
Volume values were determined using the design that was completed on the solidworks program as well
as the values that are displayed in the design outcome.
The volume of vapor was determined by seeing that roughly 10 percent of the total front area
was empty at the top. This is where the vapor would be present above the water.
Tube area and number of tubes
The surface area of the tubes were calculated using the assumed tube diameter.
The number of tubes for each pass were found by dividing A2 and A3 by the tube A_tube.

6. 6
Design Outcome:
There were many assumed and given values used for the design of the steam boiler system.
Given Values:
- The tube external diameter is 50mm, and its thickness is 3 mm.
-The thickness of furnace plate is 16mm
-The thickness of main shell is 12 mm.
-Tube diameter is 50mm
Values determined by team:
- Boiler length: 5m
- Boiler Diameter: 2m
- Furnace Diameter: 0.8m

7. 7
Excel Data (Also sent in a separate Excel File)
Assumed/Given
mass flow rate (kg/s) 1.39
pressure (Pa) 1000000
boiler length (m) 5
boiler diameter (m) 2
tubes diameter (m) 0.8
h-w 700
h-air 75
k-tube 51
t-tube (m) 0.003
T1 (celsius) 1100
T3 (celsius) 230
T-w (celcius) 180
Calculated/Determined
T2 665 h2 2778.1
T2-air 882.5 h1 88.14
T3-air 447.5
Q-in 3739.044
Q2/A2 47.39983
Q3/A3 18.04905
Q2 2692.112
Q3 1046.932
A2 56.79581
A3 58.00486
Area of tube 0.789
Number of tubes: Pass 2 72
Number of tubes: Pass 3 74
Total Number of Tubes 146

8. 8
References
Godil. Junaid. Boiler. Web. 10 Dec 2014. <http://www.nedians.8m.com/boiler.htm>
Firetube or Watertube? What is the difference? P.C.Mc.Kenzie Company. Web. 10 Dec 2014.
http://www.mckenziecorp.com/boiler_tip_8.htm
http://www.energy.kth.se/compedu/webcompedu/ManualCopy/Steam_Boiler_Technology/Heat_
exchangers/thermal_design_of_heat_exchangers.pdf