Handbook of Solvents - George Wypych - ChemTech - Ventech!

22.2 Solvent recovery 1547
Figure 22.2.4. Continuous air cleaning unit by zeolite concentrator.
Figure 22.2.5. Block diagram. Continuous air cleaning process
by zeolite concentrator.
ture is exhausted from the photoresist
at approximately 100 Nm 3 /min, 20°C
and 60% RH. Figure 22.2.3 shows the
process flow diagram. The VOC laden
feed gas (exhausted from the
photoresist) is pre-treated by filters in
two steps, first by a bag filter and then
by activated carbon. The former removes
dusts and the latter removes any
readily polymerizable vapors such as,
acrylic acid, organic silicon compounds
e.g. hexamethylene disilazane
(HMDS), phosphorous-compounds
and halogen-compounds which are all
catalyst poisons. The pretreated gas is fed to the zeolite honeycomb rotor for concentration.
(Figure 22.2.4)
Table 22.2.3 shows measurements at the designated points in the block diagram (see
Figure 22.2.5). VOC removal reached 91 % at outlet of the rotor and 98 % at outlet of the
catalytic oxidation unit.
Table 22.2.3. Measurements according to block diagram (Figure 22.2.5). Continuous
air cleaning process by zeolite concentrator
No. Point of detection Temp., °C Conc., ppm Flow rate, Nm 3 /min
1 Concentrator, inlet 26 430 102
2 Concentrator, outlet 33 40 116
3 Cat. oxidation, inlet 450 3,700
4 Cat. oxidation, outlet 490 83
5 Exhaust 39