|
THE PRINCIPLE OF AIR CURTAIN BURNING
Air Curtain Burners, also called
FireBoxes, were
designed principally as a pollution control device. The primary
objective of an air curtain machine is to reduce the particulate matter
(PM) or smoke, which results from burning clean wood waste. It is
sometimes hard to visualize without seeing a machine in operation, but
the machines do not burn anything, rather they control the results of
something burning.
You could look at it as a pollution control device
for open burning. Clean wood waste is loaded into the FireBox, and
an accelerant such as Diesel fuel is poured onto the wood and the pile is ignited.
This is very similar to starting a campfire. The air curtain is not engaged
until the fire has grown in strength or the air curtain may blow the
fire out. Once the fire has reached suitable strength, usually in 15 to 20
minutes, the air curtain is engaged. The air curtain then runs at steady
state throughout the burning operation and the waste wood is loaded at
a rate consistent with the rate of burn. Our smallest machine will burn
at a rate of 2 to 4 ton per hour, our largest machine can burn in
excess of 12 tons per hour.
Principle
The
purpose of the air curtain is to stall or slow down the smoke particles on
their way out of the FireBox. In doing this the particles are subjected
to the highest temperatures in the FireBox. Stalling the smoke particles
in this region just under the air curtain causes them to re-burn,
further reducing their size to an acceptable limit. The result is a very
clean burn with opacities well under 10% per EPA Method 9 Testing (as
compared to open burning which typically can run at 80% to 100% opacity).
Operation
 The picture to the right
shows an Air Burners FireBox S-327 completely
full and burning while in the background a pile of wood is open burned.
The wood pile that is open burning continued to burn for two weeks. That
entire pile could have been eliminated with the FireBox in less than 20
hours.
For proper operation, the air
curtain machine has to be designed to provide a curtain of air over the
fire that has a mass flow and velocity that are in balance with the
potential mass flow and velocity of the burning wood waste. If the
air curtain velocity is too high, the FireBox or Trench can become over
pressurized and over agitated. The higher pressure will lift the curtain
and cause it to become ineffective. The over-agitation will cause embers
and ash to be blown out of the box or pit past the ineffective air curtain
at a significantly higher rate than normal. If the mass flow of the
curtain is too low then the unburned particles (smoke) will penetrate
the curtain on the high velocity of the hot gasses being generated from
the burning wood.
 |
Air Curtain Burners do not
burn anything.
They control the results of
something burning. |
|
"The Wood Waste is the Fuel"
|
|
1
|
Air
curtain machine manifold and nozzles directing high velocity air
flow over and into refractory lined fire box or earthen trench.
|
|
2
|
Refractory
lined wall as on the S-Series machines, or earthen wall as used
with the T-Series trench burners.
|
|
3
|
Wood waste material
to be burned.
|
|
4
|
Initial
airflow forms a high velocity “air curtain” over fire.
|
|
5
|
Continued
air flow over-oxygenates the fire keeping temperatures high. Higher
temperatures provide near 100% combustion efficiency and that
results in a cleaner and more complete burn.
|
RECYCLING
 The
ash from typical wood waste is a very useful soil additive and as such
offers a commodity that can be marketed to plant nurseries, farms, etc.
as a potting soil additive. Recycling our resources is not only
socially and politically imperative, but it often reaps the additional
benefit of tax incentives or tax credits. Solid waste landfills are
diminishing rapidly, and permits are difficult to secure for new sites.
The Air Burners System provides an affordable and environmentally sound
alternative to grinding and the indiscriminate depositing of woody debris into landfills.
|
Related Reports |
|
Disposal of Woody
Debris by Fire with perfect combustion
efficiency releases no Black Carbon and
virtually only Biogenic CO2, making this process
carbon neutral.
CLICK HERE |
|
Air Curtain Burner vs. Wood Grinder -
Disposal of Wood Waste
A Comparison of Critical Emissions and Basic
Economic Parameters from Two Disposal Methods
CLICK HERE |
|
Disposal of Trees Affected by the Pine Beetle -
The Dilemma and why Air Curtain Burners
Should Be Used.
CLICK HERE |
|
Print This Page in PDF
Format
Previous Page
Top of Page
| 
