Carbon Monoxide Emissions from Oxygen Delignification and Chlorine Dioxide Bleaching of Wood Pulp, 1997 Pulping Conference Proceedings

Carbon monoxide (CO) is a byproduct of bleaching pulp with chlorine dioxide (ClO2) and delignification with oxygen (O2). Preliminary results from an ongoing NCASI study to investigate CO emissions from ClO2 bleaching and O2 delignification are presented. Continuous emission monitoring systems (CEMs) were used to measure CO emissions from vents on four O2 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 O2 delignification systems and ten bleach plants using ClO2 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 O2 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 O2 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 ClO2, CO emissions also seem to be dependent primarily on percent ClO2 applied on the pulp, although there is significant scatter in the data.