Review of Fluorotelomer Incineration ECA Final Report

1 / 3 Report Title: Amended Final Study Report

ECA Incineration Testing Program: Laboratory Scale Incineration Testing

of Fluorotelomer

- Based Polymers

November 17, 2010

Review by: Maj’d El

- Zoobi

OPPT/EETD/CEB

Phase I PFOA Transport Testing :

1. Reactor Temp erature 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 tempe rature. 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 r eactor during the experimental run wherein

temper ature was presumed to be at the set

- point of 2 5 0 C) was determined during the

heater calibration run by measuring the inside temperature of the reactor while the reactor walls are being heated and N 2 is flow ing in the reactor at 1,200 sccm (standar d 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 pressur e (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 composition s
, the actual temperature profile may be differe nt from the assumed one resulting in a different residence time at the

temperature set

- point than presumed. How have the authors assured that there is no significant dif ference between the temperature profile of the reactor during the

calibration of the reactor heater, and the actual temperature profile occurri ng during the experimental runs?

Phase I I Incineration Testing :

1. Reactor Temperature Profile : ( F. Combustion Testing / 1. Experimental Apparatus / a. Reactor Temperature

Profile and Related Ca lculations / P. 31 ) :Review of Fluorotelomer Incineration ECA Final Report

2 / 3 Sim ilarly to p hase I testing , the tempera ture profile of the reactor during t he 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 rea ctor (distance in reactor during the experimental run wherein temper ature was presumed to be at 100 0 C) was determined

based on this measured temperature profile. D uring heater calibration, the inside

temperatu re of the reactor was measured along the reactor length while the reactor walls were heated using the heater, and synthetic air was flow ing in the reactor at

600 sccm

.

Th e 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 hea ter ends at this length and does not cover the entire reactor? Even if that were the case, it is surprising t hat temperature would drop 600°C in the span of only 4 in. due to ambient cool ing only (ie, without the use of a cooling

device .)

In contrast t o the heater ca libration 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 reactio n and an

endothermic the rmal 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 detail ed stoichiometric calculations, but does not contain any reference to

heat effects. How have the report authors d etermine d whether the reaction heat effects will cause any significant difference between the temperature profile of the reactor during the ca libration of the reactor heater, and the actual temperature profile occurring durin g 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?

2. Cons ideration 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.Review of Fluorotelomer Incineration ECA Final Report

3 / 3 Any residue remaining on the pyroprobe after an exper imental ru n is of interest in this regard

. According to Table 8, “Pyroprobe Cartridge and Sample Weight Measurement for FTBP Composites”, a residue was formed on the pyroprobe in two

of t he nine experimental runs. A 3μg and 4 μg residue was formed in runs FTBP1

- 1

and FTBP2

- 3 respectively. T aking 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. Please explain this taking into account the above.

Another consideration in regard to the possibility that other PFC were formed is

whether a fluorine mass balance closes. Do you have any data on a fluorine balance? 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.