Handbook of Solvents - George Wypych - ChemTech - Ventech!

1564 K. A. Magrini, et al.
Figure 22.4.3. Solar insolation (left) and fractional TCE conversion (right) versus illumination time. Flow rate and
relative humidity of the incoming air stream was 10 SCFM at 20% RH. Data taken on April 8-9, 1997.
22.4.3 FIELD TEST RESULTS
22.4.3.1 Air stripper application
The field test at McClellan AFB took place during a 3-week period in April, 1997. System
operating conditions included two flow rates (10 and 20 SCFM) and variable light intensity.
The photoreactor system, designed to perform optimally at 10 SCFM with natural sunlight,
was also operated at 20 SCFM to challenge the system. Because of varying solar illumination
levels during the day, the system can operate for longer periods at lower flow rates.
Residence times in the reactor at 10 and 20 SCFM were 0.50 sec and 0.25 sec, respectively.
Figure 22.4.3 shows TCE conversion and UV intensity versus illumination time at 10
SCFM for two days of operation. UV intensities were measured with a UV radiometer
(UHP, San Gabriel, CA, Model UHX). TCE inlet concentrations varied from 10-15 ppmv.
Detection limits for the gas chromatograph were measured at 0.5 ppmv. Figure 22.4.3 indicates
that conversions greater than 95% at 10 SCFM are achieved with UV intensities at or
greater than 1.5 mW/cm 2 . At 10 SCFM, continuous destruction greater than 95% was
achieved for at least 6 hours per day on two clear days in April at this latitude (37°N). The
length of operation for a solar-driven system will vary with time of year, latitude, and altitude
due to the effect each parameter has on available solar-UV intensity.
Figure 22.4.4. Solar insolation (left) and fractional TCE conversion (right) versus illumination time during periods
of partial cloud cover. Flow rate and relative humidity of the incoming stream was 10 SCFM and 20% RH. Data
taken on April 7 and April 16, 1997.