HVLC Process Combustion Options for Kraft Pulp Mills, 1998 Cluster Rule Symposium Proceedings

High Volume Low Concentration (HVLC) streams of Non-Condensible Gases (NCG) can effectively be controlled by thermal destruction in several process units within kraft pulp mills. Combustion process options currently practiced include: power boilers (fossil fuel and waste wood), lime kilns, and recovery boilers. HVLC NCG streams in the future could also first be feed to a black liquor gasifier followed by product gas combustion in a power boiler. The MACT I regulations accept these control options and hence do not require compliance testing or modeling.

Selection of a process unit as the HVLC-NCG control technology depends on many mill specific issues. In most cases the process units were not originally designed for HVLC-NCG introduction, so, it is important to first assure the unit’s production capability is not unacceptably compromised. Characteristics of HVLC-NCG streams that present design and operational challenges include: significant volumes with respect to combustion air requirements, potentially corrosive gaseous sulfur compounds, and high moisture levels. These issues and others will be discussed to identify a strategy pulp mills can use for selecting realistic HVLC-NCG control technology options.