CARBON MONOXIDE EMISSIONS FROM OXYGEN DELIGNIFICATION AND CHLORINE DIOXIDE BLEACHING OF WOOD PULP

摘要

Carbon monoxide (CO) is a byproduct of bleaching pulp with chlorine dioxide (ClO_2) and delignification with oxygen (O_2). Preliminary results from an ongoing NCASI study to investigate CO emissions from ClO_2 bleaching and O_2 delignification are presented. Continuous emission monitoring systems (CEMs) were used to measure CO emissions from vents on four O_2 delignification systems and six bleach plants, all located in the northwestern United States. Recent CO emission data generated by mills conducting tests in the southeastern U.S. on four O_2 delignification systems and ten bleach plants using ClO_2 were also obtained and analyzed. The CEM data show long-term average CO emissions to range from 0.05 to 0.4 lb/ODTBS for the four O_2 reactors, and from 0.5 to 1.2 lb/ODTBS for the six bleach plants. Including the short-term stack test data for the southeastern O_2 reactors, CO emissions appear to increase with total oxygen charge on the brown pulp, although not all data conformed to such a relationship. For bleaching with ClO_2, CO emissions also seem to be dependent primarily on percent ClO_2 applied on the pulp, although there is significant scatter in the data.