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Process and Results for Edge AI Safety Programs Incorporating Sub-Second Machine Control, TAPPICon26

Investigating the causes of severe economizer tube thinning in a spent sulfite liquor (SSL) boiler, TAPPI Journal August 2026

ABSTRACT: In this study, the causes of tube thinning in the economizer of an ammonia-based spent sulfite liquor (SSL) boiler in a Canadian pulp mill are investigated. The tube thinning was most severe in the upper tube rows of the lowest economizer sections where the tube surface temperature ranges between about 180°C and 210°C. The location, the temperature range, and the results of a tube failure analysis indicate that some form of corrosion- erosion is the main cause for the tube thinning. The process is likely initiated by the formation of potassium bisulfate in tube deposits. We hypothesize that some areas in the economizer, including gaps in tube shields, have allowed for temporary buildup of deposits that were not fully removed by sootblowing. Potassium bisulfate is highly hygroscopic, so it readily absorbs moisture, forming an acidic solution leading to corrosion. The corrosion products are removed by the erosive effects of high velocity gas movement, causing the tube thinning. The high-speed fluid flow may be a result of sootblower action and/or enhanced flue gas velocity due to channeling. The tube thinning eventually leads to perforation and leakage.

Effect of Defoamer on the Gas Content and Performance of O2 washers • Mill Case Study, 19PEERS

Effect of Defoamer on the Gas Content and Performance of O2 washers • Mill Case Study, 19PEERS

Optimizing Mill Effectiveness Through Statistical Process Control (SPC), 19PEERS

Optimizing Mill Effectiveness Through Statistical Process Control (SPC), 19PEERS

Study on Recovered Paper Quality in Germany and Method for Determining the Composition of Recovered Paper Samples, 19PEERS

Study on Recovered Paper Quality in Germany and Method for Determining the Composition of Recovered Paper Samples, 19PEERS

A Method for Analyzing Basis Weight Profile in Recycled Paper Mills, 19PEERS

A Method for Analyzing Basis Weight Profile in Recycled Paper Mills, 19PEERS

Refining: Recycled Fiber for Tissue Production, 19PEERS

Refining: Recycled Fiber for Tissue Production, 19PEERS

SIMULTANEOUS PRECIPITATION IN AN ECF KRAFT PULP MILL: LONG-TERM EXPERIENCES, 19PEERS

SIMULTANEOUS PRECIPITATION IN AN ECF KRAFT PULP MILL: LONG-TERM EXPERIENCES, 19PEERS

MILL EXPERIENCE OF CALCIUM CARBONATE SCALE FORMATION IN GREEN LIQUOR HANDLING SYSTEMS, 19PEERS

MILL EXPERIENCE OF CALCIUM CARBONATE SCALE FORMATION IN GREEN LIQUOR HANDLING SYSTEMS, 19PEERS

Fate of Phosphorus in the Lime Cycle of the Kraft Pulping Process, 19PEERS

Fate of Phosphorus in the Lime Cycle of the Kraft Pulping Process, 19PEERS