To: Don and Others:
The relationship of ink loading (coverage plus press speed) and
destruction efficiency of catalytic type oxidizers can be very difficult to
determine. The conundrum then for operators of this type of emissions control is
to determine the best way to measure and demonstrate destruction
efficiency. Regulatory agencies want testing to be done on a "worse case-maximum
emissions" basis. So what is truly the worse case scenario?
Keep in mind that printing industry operations may be best characterized
as "non-steady state" (presses going up and down constantly for color
okays, adjustments, etc.), and also as "high-variability" ( sometimes we
"paint" the sheet, and other times there is hardly any ink coverage).
Catalytic type oxidizers would appear to have a somewhat narrow "ideal"
operating range for highest destruction efficiency (assuming good,
uncontaminated catalyst and proper operating temperature).
In real production scenarios, the "worse case" emissions example may very
well be opposite of what one would normally assume. Higher ink loading
does not necessarily equal higher emissions and lower destruction
efficiency. Here's why.
Draw a straight line incline representing increased ink loading from the
lightest on the lower left to the heaviest (100% coverage) on the upper
right. Superimpose on this graph one representing increased catalyst
efficiency, a slowly upward arching curve from the lower left to the upper right
(theoretical 100% destruction efficiency at the upper right). Finally, a
second curve may be superimposed on the first two graphs, this one in the
shape of a bell curve representing particles (ppm) of emissions.
Now let's look at these together. As ink loading increases with coverage
and/or press speed, the catalyst also increases efficiency as it now has
more fuel. At lower levels of fuel (dryer emissions) on the lower left
side, the actual emissions (particles) are also low. As we move to the right,
both efficiency and ink loading continues to increase to some point (the
top of the bell curve) where ctalyst efficiency continues to increase and
emissions begin to show a decrease even with increased loading (the
downward swing of the bell curve).
Now here's the kicker! If the type of printing you do at your facility
represents the range from A) partway up the straight line representing ink
loading and also partway up the bell curve of particles of emission to B)
full ink loading at high caqtalyst efficiency and low emissions on the
right, then it is very possible for your facility's "light loading scenario"
to have higher actual emission than when you facility runs at its "heavy
loading scenario", exactly the opposite of what one expect!
So now it would appear that your "worse case " scenario would exist under
light loading of your catalytic oxidizer
Complicating things even further, the concept of "destruction
efficiency", merely a ratio between input and output from a control device, leads us
further astray from being focused on the residual emissions after controls
are applied. In summary, low ink loading may "demonstrate" terrible
destruction efficiencies all the while accounting for very few actual
emissions. If for compliance purposes, the focus is on "destruction efficiency" and
this "defines" compliance, then it becomes extremely difficult to
This explanation, and curves, were made known to me by a manufacturer who
had conducted some controlled tests a number of years ago. I have a
feeling that most manufacturers of catalytic units (for printing, other
applications that are steady-state and not so variable may be fine) would rather
avoid discussing this characteristic of catalytic oxidizers.
I hope this rather lengthy explanation will shed some light on your
issue. The best I can recommend is to try negotiating your test conditions with
your regulatory agency so that you can use actual work in progress for
testing catalytic efficiency. To do otherwise (use dummy jobs to demonstrate
compliance) seems inconsistent with all our other efforts to reduce
waste. This conundrum may be a good reason to shift to termal oxidizers in the
The John Roberts Company
>From: "Don Eggleston"<firstname.lastname@example.org>
> 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.