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Magazine articles
Effects of agitator blade scaling on mixing in dissolving tanks, TAPPI Journal April 2022
ABSTRACT: Hard calcium carbonate scale often forms on the agitators in smelt dissolving tanks. The effects of this scale on mixing are not well understood. While mixing in tanks has often been modeled in the literature, there have been no studies involving agitator scaling. To better understand the impact of agitator scaling on hydrodynamics and tank concentrations, a steady state, three-dimensional (3D) model has been developed for a smelt dissolving tank at a kraft pulp mill. In this work, four cases are compared: an agitator with no scaling, mild scaling, moderate scaling, and extreme scaling. The extreme scaling case is representative of scale buildup on a dissolving tank agitator that was significant enough that the agitator had to be stopped and cleaned. The reduction in the agitator fluid jet velocity is relatively small for the mild and moderate scaling cases, but it becomes more significant for the extreme scaling case, for which the results indicate that the mixing of the smelt with the weak wash is likely poor and that there would thus be a risk of smelt pooling.
Journal articles
Magazine articles
Experiments and visualization of sprays from beer can and turbo liquor nozzles, TAPPI Journal February 2022
ABSTRACT: Industrial scale swirl-type black liquor nozzles were studied using water as the test fluid. Simple water spraying experiments were found to be very beneficial for studying and comparing nozzles for black liquor spraying. These kinds of experiments are important for finding better nozzle designs. Three nozzle designs were investigated to understand the functional differences between these nozzles. The pressure loss of nozzle 1 (“tangential swirl”) and nozzle 3 (“turbo”) were 97% and 38% higher compared to nozzle 2 (“tan-gential swirl”). Spray opening angles were 75°, 60°, and 35° for nozzles 1, 2, and 3, respectively. Video imaging showed that the nozzles produced sprays that were inclined a few degrees from the nozzle centerline. Spray patter-nation showed all the sprays to be asymmetric, while nozzle 2 was the most symmetric. Laser-Doppler measure-ments showed large differences in spray velocities between nozzles. The spray velocity for nozzle 1 increased from 9 m/s to 15 m/s when the flow rate was increased from 1.5 L/s to 2.5 L/s. The resulting velocity increase for nozzle 2 was from 7 m/s to 11 m/s, and for nozzle 3, it was from 8 m/s to 13 m/s. Tangential flow (swirl) directed the spray 6°•12° away from the vertical plane. Liquid sheet breakup mechanisms and lengths were estimated by analyzing high speed video images. The liquid sheet breakup mechanism for nozzle 1 was estimated to be wave formation, and the sheet length was estimated to be about 10 cm. Sheet breakup mechanisms for nozzle 2 were wave formation and sheet perforation, and the sheet length was about 20 cm. Nozzle 3 was not supposed to form a liquid sheet. Nozzle geometry was found to greatly affect spray characteristics.
Magazine articles
Recycling 'low value' post-consumer fibers to improve quality and reduce costs, TAPPI JOURNAL, September 1997, Vol. 80(9)
Recycling 'low value' post-consumer fibers to improve quality and reduce costs, TAPPI JOURNAL, September 1997, Vol. 80(9)
Magazine articles
1998 international chemical recovery conference, TAPPI JOURNAL, December 1998, Vol. 81(12)
1998 international chemical recovery conference, TAPPI JOURNAL, December 1998, Vol. 81(12)
Magazine articles
CEO forecast: the recovery has arrived, TAPPI JOURNAL, January 1995, Vol. 78(1)
CEO forecast: the recovery has arrived, TAPPI JOURNAL, January 1995, Vol. 78(1)
Magazine articles
Supplier forecast: suppliers feel ripples from the recovery, TAPPI JOURNAL, January 1995, Vol. 78(1)
Supplier forecast: suppliers feel ripples from the recovery, TAPPI JOURNAL, January 1995, Vol. 78(1)
Magazine articles
Corrosion of titanium in alkaline hydrogen peroxide bleaching solution, TAPPI JOURNAL, June 1995, Vol. 78(6)
Corrosion of titanium in alkaline hydrogen peroxide bleaching solution, TAPPI JOURNAL, June 1995, Vol. 78(6)
Magazine articles
Corrosion of nickel-base alloys in chlorine dioxide environments, TAPPI JOURNAL, June 1995, Vol. 78(6)
Corrosion of nickel-base alloys in chlorine dioxide environments, TAPPI JOURNAL, June 1995, Vol. 78(6)
Magazine articles
How will integrated gasification impact kraft pulping and chemical recovery, TAPPI JOURNAL, September 1999, Vol. 82(9)
How will integrated gasification impact kraft pulping and chemical recovery, TAPPI JOURNAL, September 1999, Vol. 82(9)
Journal articles
Magazine articles
Combatting lime kiln ringing problems at the Arauco Constitución mill, TAPPI Journal July 2020
ABSTRACT: The lime kiln at the Arauco Constitución mill experienced severe ringing problems requiring it to be shut down for ring removal every 3 to 6 months. The mill controlled the problems by blasting ring deposits off during operation with its existing industrial shotgun and a newly installed Cardox liquid carbon dioxide (CO2) cartridge system. Various ring blasting procedures were tested to determine the optimum ring location and thickness to blast; the optimum depth to insert the CO2 cartridge into the kiln; and the most effective blasting frequency and sequence to employ. The best strategy was found to be the weekly blasting operation that alternated between the liquid CO2 cartridge and the industrial shotgun, with the CO2 cartridge inserted into the ring mass, 20 cm (8 in.) away from the refractory brick surface, and the shotgun aimed at rings at about 28 m (92 ft) from the kiln discharge end. With each blasting event removing considerably more rings than before, it takes a longer time for rings to rebuild, allowing the kiln to run continuously between annual maintenance shutdowns with only a few short (< 4 h) downtimes for ring removal. This substantially reduces the costs associated with ring removal and lime replacement during unscheduled shutdowns.