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Journal articles
Commissioning Brownstock Washing Controls for an Evaporator Limited Mill
An automated shower water control system has been implemented to reduce the volume and vari-ability of weak black liquor being sent from the pulp mill to the evaporators. The washing controls attempt to bal-ance the need for consistent and low soda carryover to the bleach plant with consistently high weak black liquor solids being sent to the evaporators. The washer controls were implemented on two bleachable grade hardwood lines (one with oxygen delignification, one without oxygen delignification) and one pine line. Â Implementation of the con-trol program resulted in an increase in black liquor solids of 0.6 percentage points for the hardwood lines. Significant foam reduction was realized on the pine line since the pine black liquor solids were able to be consistently maintained just below the soap separation point. Low black liquor solids excursions to the evaporators were eliminated. Bleach plant carryover was stabilized and no negative impact on chemical consumption was noticed when control-ling weak black liquor solids to recovery.
Journal articles
Corrosion Monitoring and Root Cause Identification in High Solids Concentrators
Black liquor high solids (about 80%) concentrators have often been found to suffer from aggressive corrosion. In particular, the first and second effect bodies are susceptible to corrosion attacks resulting in tube leaks and wall thinning, which limit the availability and lifetime of evaporator lines. Corrosion dynamics and construction materials have been studied extensively within the pulp and paper industry to understand the corrosion process. However, it has been challenging to identify root causes for corrosion, which has limited proactive measures to minimize corrosion damage. Corrosion of the first phase concentrator was studied by defining the potential regions for passive area, stress corrosion cracking, pitting corrosion, and general corrosion. This was achieved by using a technique called polarization scan that reveals ranges for the passive area in which the equipment is naturally protected against corrosion. The open circuit potential, also known as corrosion potential, and linear polarization resistance of the metal were monitored online, which allowed for definition of corrosion risks for stainless steel 304L and duplex stainless steels 2205 and SAF 2906. An online temperature measurement added insight to the analysis. A process diagnostics tool was used to identify root causes of the corrosion attacks. Many of the root causes were related to process conditions triggering corrosion. Once the metal surface was activated, it was difficult to repassivate the metal naturally unless a sufficient potential range was reached.
Journal articles
Bleaching optimization at WestRock mill in Covington, Virgi
Bleaching optimization at WestRock mill in Covington, Virginia, TAPPI JOURNAL September 2016
Journal articles
Using white liquor as the alkali source in oxygen delignific
Using white liquor as the alkali source in oxygen delignification, TAPPI JOURNAL September 2016
Journal articles
Magazine articles
Does the kappa number method accurately reflect lignin content in nonwood pulps?, TAPPI Journal November 2018
Does the kappa number method accurately reflect lignin content in nonwood pulps?, TAPPI Journal November 2018
Journal articles
Magazine articles
Understanding the pulping and bleaching performances of eucalyptus woods affected by physiological disturbance, TAPPI Journal November 2018
Understanding the pulping and bleaching performances of eucalyptus woods affected by physiological disturbance, TAPPI Journal November 2018
Journal articles
Magazine articles
Editorial: Looking back and looking forward: Paper physics and the paper industry, TAPPI Journal October 2018
Editorial: Looking back and looking forward: Paper physics and the paper industry, TAPPI Journal October 2018
Journal articles
Magazine articles
A review of green liquor scale formation, TAPPI Journal October 2018
A review of green liquor scale formation, TAPPI Journal October 2018
Journal articles
Magazine articles
A Theory for the Tensile Strength of Paper, TAPPI Journal October 2018
A Theory for the Tensile Strength of Paper, TAPPI Journal October 2018
Journal articles
Magazine articles
Editorial: PaperCon: A ten-year journey of papermaking excellence, TAPPI JOURNAL September 2018
Editorial: PaperCon: A ten-year journey of papermaking excellence, TAPPI JOURNAL September 2018