After many years of being involved in stack testing from a compliance,
diagnostic and engineering point of view, I have found that universally,
low inlet loads will tend to produce low destruction removal or capture
efficiencies, by any test method. This concept is universally
applicable to thermal oxidizers, adsorbers, absorbers, electrostatic
precipitators etc as well as a wide variety of contaminantes especially
To increase the potential for passing a compliance stack test, the
general rule of thumb is to run with a heavy steady VOC load, highest
rated thermal oxidizer temperature (one the thermal oxidizer recommends
or bases his guarantee on), lowest volume of air and to use the right
test method. In addition, the catalyst (if not new) should be checked
by the manufacturer for activity and regenerated, replaced or cleaned if
necessary. Catalytic element seals should also be checked for
integrity. At the least, the catalyic elements should be cleaned prior
to a compliance stack test.
Equally important is the correct test method. Environmental enforcement
agencies have a tendency to use EPA Method 25, which is the carbon base
analysis method and reports VOC concentrations as "carbon". Althought
there have been many (claimed) improvements in the test method, the
method still tends to report higher outlet concentrations than other
test methods, when the outlet concentration is low. This can lead to
failure to prove compliance.
If the agency is knowlegeable and receptive to negotiations, then the
basis or justification for a variance from the use of EPA Method 25
would be to prove a low outlet pollutant (VOC) concentration. This will
require the calculation of the outlet concentration. For example, the
State of NJ will allow the use of an alternate test method if the
concentration of VOC's in the thermal oxidizer outlet is below 50 ppmv
The alternate test method is usally EPA Method 25A or a similar method,
that reports VOC concentrations as "methane" or similar organic (i.e.
pentane, butane etc). Avoid test mehods that speciate the contaminants.
I agree with and understand Mr. Jeff Adrian on the first two curves, but
not on the bell curve that represents "particles", since a catalytic
thermal oxidizer will foul if there are particles in the air stream.
There may be condensed oil (aerosols) in the gas stream if the
concentration is high and the temperature drops on its way to the
thermal oxidizer, but the preheat or the combustion chamber temperatures
should vaporize any oil aerosols such that only organics in the vaporous
state will enter the catalyst, at normal catalytic preheat temperatures
of 800 degrees F or so.
Best of luck...Actually best of preparations.
William Bertele, P.E., DEE
New Hope, PA
Wayne Pferdehirt wrote:
> From: "Don Eggleston"<firstname.lastname@example.org>
> To: <email@example.com>
> Does anyone know if a set of efficiency curves and or tables
> exist for helping to determine what press running parameters
> should be in order to attain a certain desired destruction
> efficiency of a catalytic incinerator hooked up to a heatset web
> press with multiple dryer ovens? Specifically, something like a
> matrix relating air flow, amount of ink on the web, catalyst type
> and temperature, and resulting hydrocarbon conversion efficiency.
> The manufacturer of our system (MEGTEC) does not have this kind
> of data, and had no idea as to where it could be obtained, or if
> it existed.
> What I am trying to do is establish a guideline that allows us to
> determine what "real jobs" on the press will give us a good
> chance of passing our required emissions testing to show
> destruction efficiency. In the past we have been putting on "test
> only" jobs that are very costly. I would like to be able to
> select actual customer jobs for these tests but I am not sure
> which jobs will cause us to pass or fail the emissions testing.