Abstract
Operation of a pilot scale activated carbon CFC 11 recovery unit has been studied. For CFC 11 the trapping efficiency of the scrubber is close to 100% immediately after regeneration, falling to 95% when 12% by weight CFC has been added to the scrubber. About 10–15% of the CFC used by the plant is captured. Recovery is less efficient due to losses in the condenser, and only 50–60% of the trapped material is obtained for re-use. Examination of this material has shown significant differences from the unused sample, but admixture of recovered with unused CFC has proved successful in plant operations.
For TDI, the unit is 100% efficient input concentrations as high as 3 ppm being reduced to the non-detectable level at the outlet (limit of detection 0.005 ppm). The current calculated TDI loading is 2% by weight of the carbon.
For the tertiary amine catalysts used on the plant input concentrations were 0.5–7.1 ppm for DMEA and less than 0.1 ppm to 2.5 ppm DABCO. Outlet concentrations were 0.1 to 0.4 ppm for DMEA and were not detectable for DABCO (limit of detection 0.05 to 0.1 ppm).
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