Document ID: EPA-HQ-OPPT-2004-0001-0136
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2015-02-19T05:00Z

Report Title: 	Amended Final Study Report

ECA Incineration Testing Program: Laboratory Scale Incineration Testing
of Fluorotelomer-Based Polymers

December 22, 2008

Review by: 	Maj’d El-Zoobi

	OPPT/EETD/CEB

Phase I PFOA Transport Testing:

Reactor Temperature Profile:

(A.  Experimental Apparatus / 2.  Reactor Temperature Profile and
Related  Calculations / P.19)

The reactor consisted of a 1.4 cm diameter quartz tube placed in a
heater used for supplying heat to maintain the reactor at the desired
temperature.  The reactor outside wall temperature was measured during
the experimental runs, but the reactor inside temperature (temperature
of reactor contents) was only measured during the heater calibration
run. 

The effective reactor length (distance in reactor during the
experimental run wherein temperature was presumed to be at the set-point
of 250 C) was determined during the heater calibration run by measuring
the inside temperature of the reactor while the reactor walls are being
heated and N2 is flowing in the reactor at 1,200 sccm (standard cubic
centimeters per minute). 

In contrast, experimental runs consisted of combined air flow at 1378
sccm and water vapor flow at 158.2 sccm.  Given the difference between
the heat capacities at constant pressure (Cp) of nitrogen, oxygen, and
especially water vapor (~ 7, 7.25, 8.5 cal/gmol C at ~ 500 C,
respectively), and the different heat transfer effects resulting from
the two different flow rates and compositions, the actual temperature
profile may be different from the assumed one resulting in a different
residence time at the temperature set-point than presumed.  Based on
this, it is recommended that the report authors conduct an analysis of
error to determine whether there is any significant difference between
the temperature profile of the reactor during the calibration of the
reactor heater, and the actual temperature profile occurring during the
experimental runs. 

Phase II Incineration Testing:

Reactor Temperature Profile: 

(F. Combustion Testing / 1.  Experimental Apparatus / a.  Reactor
Temperature Profile and Related  Calculations / P.31):

Similarly to phase I testing, the temperature profile of the reactor
during the experimental runs was presumed to be identical to the
temperature profile that was measured during the heater calibration run.
 This method for establishing the temperature profile during the
experimental runs was specified in the phase II testing QAPP
(OPPT-2004-001-0116.1) because “it is not practical to directly
monitor the inside gas temperature at the midpoint of the reactor tube
during each experimental run.”  Also, the effective length of the
reactor (distance in reactor during the experimental run wherein
temperature was presumed to be at 1000 C) was determined based on this
measured temperature profile.  During heater calibration, the inside
temperature of the reactor was measured along the reactor length while
the reactor walls were heated using the heater, and synthetic air was 
flowing in the reactor at 600 sccm. 

The following questions are related to the heater calibration:

The reactor was held at 1000°C for most of its length, but the heater
temperature set-points were in the range of 979°C to 993°C.  However,
heat transfer from heater to quartz tube requires that the temperature
of the earlier be higher than that of the later which is contrary to
what is reported; is this explained by an erroneous heater temperature
controller, such that the actual heater set-point is actually greater
than 1000°C?  Also, why does the reactor’s temperature drop beginning
at length 32 in.?  Is that because the heater ends at this length and
does not cover the entire reactor?  Even if that were the case, it is
surprising that temperature would drop 600°C in the span of only 4 in.
due to ambient cooling only (ie, without the use of a cooling device.) 
It is recommended that these questions be addressed by the report
authors.

In contrast to the heater calibration run, reactor feed during the
experimental run consisted of methanol fuel and the vaporized test
material in addition to synthetic air.  Methanol and the test material
undergo an exothermic combustion reaction and an endothermic thermal
degradation reaction respectively whose heat effects, depending on their
magnitude, may influence the temperature profile in the reactor that is
formed due to the heating by the heater.  Appendix 7 of the report
((OPPT-2004-001-0126.7) contains detailed stoichiometric calculations,
but does not contain any reference to heat effects.  It is recommended
that the report authors conduct an analysis of error to determine
whether the reaction heat effects will cause any significant difference
between the temperature profile of the reactor during the calibration of
the reactor heater, and the actual temperature profile occurring during
the experimental runs to ensure that the correct effective length was
determined and consequently that the desired residence time of 2 sec.
was actually established.

Consideration of Formation of Other PFC:

A determination of whether other perfluorinated chemicals (PFC) were
formed as a result of the thermal destruction of the composite test
material is of interest.  

μg and 4μg residue was formed in runs FTBP1-1 and FTBP2-3
respectively.  Taking into account balance accuracy of ±2.5 μg, the
amount of residue is 0.5μg and 1.5μg for runs FTBP1-1 and FTBP2-3
respectively.  However, in the report (F. Combustion Testing / 2.
Description of Test Conditions / a. Test Substance Weight Measurements /
P. 33) it is stated that the residue reported in Table 8 for these two
runs is within the weighing accuracy of the microbalance.  This
statement should be explained by the report authors and the formation of
the implications of the formation of the residue should be discussed.

	

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re formed is whether a fluorine mass balance closes.  This has yet to be
determined by the reviewer.  Note that a carbon mass balance is not of
use in this regard because methanol is by far the source of carbon in
the feed.

       

    

   

  DATE \@ "M/d/yyyy"  9/1/2009 

Review of Fluorotelomer Incineration ECA Final Report

  PAGE  1 /  NUMPAGES  3