Eclipse ImmersoJet v2.20 Design Guide 330, 10/02
Efficiencies 80% or more
1/2”
Drain
Pipe
Stack–
Twice
Tube
Diameter
Efficiencies less than 80%
Elbows
•
Use standard and sweep elbows only.
•
For maximum tube life place the first elbow eight tube
diameters from the burner.
Stack
•
Make sure that the stack is large enough to handle the
heated exhaust flow plus the dilution air.
•
The stack must be at least one pipe size larger than the tube
exhaust.
n
Note:
If you use a common stack for more than one burner, then
make sure that the stack is large enough to handle the
exhaust flow plus any dilution air from all the burners.
Detailed guidelines for flue sizing calculations are in the
Eclipse Combustion Engineering Guide (EFE 825).
Stack
Draft breaking
hood
Dilution air
Tube exhaust
14
Draft breaking hood
A draft breaking hood is an open connection between the heater
tube exhaust and the exhaust stack. It allows fresh dilution air to
pass into the exhaust and mix with the exhaust gases.
The advantages of a draft hood are:
•
the burner operation is less sensitive to atmospheric conditions
•
the temperature of the exhaust gases is lower when they
pass through the roof.
n
Note:
Leave access between the draft hood and the tube exhaust. Install
a damper plate if acoustic feedback occurs in the tube.
Condensate provisions
If the immersion tube will operate at efficiencies less than 80%,
the exhaust leg can be raised through the liquid surface. For
efficiencies of 80% or higher, locate the exhaust stack outside of
the tank and provide a drain.
n
Note:
Regardless of the exhaust design, pitch the immersion tube down
towards the exhaust so condensate will not collect at the burner.
c
Caution:
At efficiencies of 80% or greater, low exhaust temperatures
will cause condensation to form in the tube at start-up or
during long idling periods. The higher the efficiency the more
condensation will increase
To prevent condensation/corrosion from shortening tube life or
disrupting burner operation, provide a condensate drain at the
exhaust and slope the immersion tube downward, away from
the burner.
Tube placement in tank
The tube placement height in the tank should be high enough to
avoid the possibility of sludge build-up on the bottom of the tank;
however, it should be low enough to avoid tube exposure due to
liquid level variations caused by evaporation or displacement. In
the latter case use a liquid level switch to shut down the burner.
