Experience in the Start-up and Operation of a NCG Collection and Burning System at a RDH Pulping Facility, 1994 Environmental Conference Proceedings

S. Freeburn, M. Barfield

In 1989 Willamette Industries, Inc. commissioned its Marlboro Mill in Bennettsville, South Carolina. The mill design incorporated Rapid Displacement Heating (RDH) digesters to accomplish energy efficient, low kappa pulping of both softwood and hardwood. The mill also incorporated a foul condensate stripper and a comprehensive non-condensable gas (NCG) collection and incineration system to minimize odors and the release of hazardous air pollutants. The adaptation of a standard NCG collection and burning system to the RDH process presented new requirements for the collection system design and incinerator operation. Marlboro experienced operational difficulties in pulping liquor foam in the stripper, fiber entering the NCG collection system and turpentine condenser, surging in the collection system and turpentine condenser, surging in the collection systems and incinerator and over-temperature trip outs of the incinerator safety systems. After several corrective measures to achieve better control of the stripper, digester, and collection systems, modifications were made to reduce fuel load to the incinerator. This included diversion of the low concentration gas streams to another combustion unit. Operational problems are being further addressed by plans to redirect high strength gas streams to boilers and/or kilns where odorous and toxic components can be effectively burned while recovering energy for process operations.