Operat Operational Methyl Bromide Rec Recapture Systems Gary F. Kn . Knapp GFK Cons nsulting
Summary – Emission R Reduction Mass Emitted Maximum Concentration Without Recapture 19.6 lbs Without Recapture 16,000 ppm With Recapture 4.2 lbs With Recapture 500 ppm =79% Reduction =97% Reduction
Estimated Emissions 15.4 Assumptions: • 40 ft. container with 40,000 lbs commodity • 5,000 cubic feet fumigated space • MeBr concentration of 4 lb/1000 3.2 cubic feet 0.4 1.0 • 20 lbs methyl bromide applied Commodity C Leakage Bypass Adsorber Tota otal Emission 4.2 lbs over 3-4 hours
D/FW International Peri Perishable Treatment Center Recapture system - left view D/FW International Perishable Treatment Center Recapture system - right view
Well-Pict Strawberries es Watsonville, CA Fu Fumigation chambers Fumigation chambers and Great Lakes Recapture System
Well-Pict Strawberries es Watsonville, CA Recapture system showing carbon canister, blower, and exhaust stack Carbon a adsorber canister containin ing 2,500 lb. activated ed carbon
George Bush Internation tional Airport, Houston Treatment and Inspection building Methyl Bromide Recapture e System
System Schematic Air with ith <500 ppm MB Air with MB MB Located at Fumigation Adsorber fumigation facility Chamber C Carbon with 10% MB Make-up carbon as needed MB Desor orber Located at carbon regeneration site MB Br 2 HBr MB Bromine Ther ermal Production Production Destru truction
Recapture System Deve evelopment Conducted under a Cooperative ive Research and Development Agreement with USDA-ARS and nd GFK Consulting, 1995-99 Mobile unit built by Tigg Engnieering and Lab and Pilot Work at ARS Lab in Fresno, tested at fumigation facilities on the East CA with Dr. James Leesch and West Coasts
Fumigation Procedure Container is in place and co covered with tarp Introduce fumigant into tarp arped space, monitor concentration At the end of the fumigation tion period, open the tarp and begin recovery ventilation When concentration reache ches target concentration (250- 500 ppm) as indicated by d y detectors, switch to bypass ventilation When concentration reache ches 5 ppm, cease ventilation and remove tarp and comm modity
Concentration Profiles Fumigation period 100000 MeBr Concentration, ppm Begin Aeration 10000 Enclosure Stack 16,000 ppm 1000 Switc itch to bypass at 500 500 ppm 100 Terminate aeration ~5 ppm from at 5 ppm fumigation bay 10 1 ~1 ppm fro from adsorber e r exhaust 0.1 0 Note log scale 20 40 60 80 100 120 Enclosure 140 160 180 Time, Minutes
Typical Fumigation - Assu Assumptions • 40 ft. container with 40,000 000 lbs commodity • 5,000 cubic feet fumigated ated space • MeBr concentration of 4 lb 4 lb/1000 cubic feet • 20 lbs methyl bromide app applied
Fumigation - Initiation 20 lbs MeBr
Estimated Emissions - - Fumigation Leakage through tarp – 1.0 lbs (5%) estimated Absorbed onto commodity and packaging – 4 lbs estimated
Estimated Emissions - - Aeration (R (Recapture) 14.4 lbs to to adsorber
Estimated Emissions - - Aeration (Bypass) 3.0 lbs to to bypass
Material Balance 4.2 pounds 0.4 pounds 15.4 pounds
Estimated Emissions 15.4 Assumptions: • 40 ft. container with 40,000 lbs commodity • 5,000 cubic feet fumigated space • MeBr concentration of 4 lb/1000 3.2 cubic feet 0.4 1.0 • 20 lbs methyl bromide applied Commodity C Leakage Bypass Adsorber Tota otal Emission 4.2 lbs over 3-4 hours
Summary – Emission R Reduction Mass Emitted Maximum Concentration Without Recapture 19.6 lbs Without Recapture 16,000 ppm With Recapture 4.2 lbs With Recapture 500 ppm =79% Reduction =97% Reduction
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