Bull. Spec. CORESTA Congress, Brighton, 1998, p. 193, STPOST3
Phosphine abatement at Philip Morris
Philip Morris USA, Research Center, Richmond, VA, USA
Philip Morris has developed and implemented abatement technology to control residual phosphine gas after the fumigation of tobacco warehouses. In parallel with this, we investigated the use of electrochemical cell sensor monitors, to replace the more cumbersome and less precise Draeger tube technology. Electrochemical monitors allowed us to conduct laboratory scale experiments to evaluate the various technologies under development, and assisted in the scale-up to full-size abatement units in the field. Philip Morris began investigation of phosphine abatement in 1986, using silver-impregnated carbons. Liquid scrubber experiments began in 1993 and were optimized in 1994, being tested at full scale head-to-head with two carbons from Calgon Carbon Corporation, a 2% silver/carbon, and their then-novel CENTAUR™. CENTAUR™ was qualified for phosphine adsorption. Cost, ease of operation, and waste handling considerations led us to chose CENTAUR™ for implementation at our warehouse complexes. Research efforts conducted from 1995 to 1998 have led to improved performance of CENTAUR™ and related carbons. Details of this, and of the liquid scrubber will be presented in the accompanying presentation. Low-noise abatement units have been constructed of four or six foot diameter size, with nominal rated gas flows of 1000 and 2000 cfm, through 36 inches of granular carbon. Carbon usage is circa 1350 and 2700 pounds per unit. Dampers allow reduced flow rates, if induction periods occur. These units completely adsorb phosphine, and allow a warehouse to be cleared down to less than 10 ppm of phosphine. Phosphine is oxidized to species retained by the carbon. Carbon re-use and longevity are being studied. The used carbon is finally returned to the supplier for reactivation and recycling into the carbon pool. Abatement has been implemented at all but one Philip Morris warehouse site in the USA. Electronic hand-held monitors are currently being provided by Analytical Technology, Inc. (Ati).