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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.
Journal articles
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Viscoelastic web curl due to storage in wound rolls, TAPPI Journal July 2020
ABSTRACT: Winding is often the final operation in a roll-to-roll manufacturing process. Web materials, i.e., materials that are thin compared to their length, are wound into rolls because this form is the only practical means to store them. The resulting bending strains and associated stresses are large for thick webs and laminates. As many webs are viscoelastic on some time scale, bending stresses lead to creep and inhomogeneous changes in length. When the web material is unwound and cut into discrete samples, a residual curvature remains. This curvature, called curl, is the inability for the web to lie flat at no tension. Curl is an undesirable web defect that causes loss of productivity in a subsequent web process. This paper describes the development and implementation of modeling and experimental tools to explore and mitigate curl in homogenous webs. Two theoretical and numerical methods that allow the prediction of curl in a web are developed: a winding software based on bending recovery theory, and the implementation of dynamic simula-tions of winding. One experimental method is developed that directly measures the curl online by taking advantage of the anticlastic bending resulting from the curl. These methods are demonstrated for a low-density polyethylene web.
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SetPoint: Reach Out and Touch Someone, Paper360º July/August 2020
SetPoint: Reach Out and Touch Someone, Paper360º July/August 2020
Journal articles
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Industrial LED Lighting Improves Pulp & Paper Mill Safety, Paper360º July/August 2020
Industrial LED Lighting Improves Pulp & Paper Mill Safety, Paper360º July/August 2020
Journal articles
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Invisible Waste in Maintenance Organizations, Paper360º July/August 2020
Invisible Waste in Maintenance Organizations, Paper360º July/August 2020
Journal articles
Magazine articles
Development of a fast brightness testing method for mechanical pulp based on microwave oven drying, TAPPI Journal June 2020
ABSTRACT: Brightness is an important quality parameter for pulp products, and it is important to have reliable measurement of pulp brightness in a timely manner for process control and/or quality control purposes. In these circumstances, a quick testing method for pulp brightness is highly desirable.A rapid handsheet brightness testing method for lignin-rich mechanical pulp has been developed, which is based on the use of tap water to make handsheets and microwave ovens to rapidly dry the handsheet. Microwave oven fast drying decreased the handsheet brightness of mechanical pulp by 5•6 points due to the lignin-originated discol-oration reactions. The spray of ascorbic acid and ethylenediaminetetraacetic acid (EDTA) solutions to the handsheet can effectively inhibit these lignin discoloration reactions.With 0.2% ascorbic acid and 0.2% EDTA spraying on the wet pulp handsheet, the brightness of the handsheet from a peroxide-bleached stone groundwood pulp after the microwave oven fast drying method was similar to that obtained from the same pulp but following TAPPI Standard Test Method T 272 sp-12 “Forming handsheets for reflectance testing of pulp (sheet machine procedure)”. The effect of handsheet dryness on the handsheet brightness was also studied, and the results showed that the brightness reading was almost constant in the dryness range of 70% to 90%. The method developed is a reliable, fast brightness testing method for lignin-rich pulp that is of practical interest in industrial operations.
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Integrated study of flue gas flow and superheating process in a recovery boiler using computational fluid dynamics and 1D-process modeling, TAPPI Journal June 2020
ABSTRACT: Superheaters are the last heat exchangers on the steam side in recovery boilers. They are typically made of expensive materials due to the high steam temperature and risks associated with ash-induced corrosion. Therefore, detailed knowledge about the steam properties and material temperature distribution is essential for improving the energy efficiency, cost efficiency, and safety of recovery boilers. In this work, for the first time, a comprehensive one-dimensional (1D) process model (1D-PM) for a superheated steam cycle is developed and linked with a full-scale three-dimensional (3D) computational fluid dynamics (CFD) model of the superheater region flue gas flow. The results indicate that: (1) the geometries of headers and superheater platens affect platen-wise steam mass flow rate distribution (3%•7%); and (2) the CFD solution of the 3D flue gas flow field and platen heat flux distribution coupled with the 1D-PM affect the platen-wise steam superheating temperature (45%•122%) and material temperature distribution (1%•6%). Moreover, it is also found that the commonly-used uniform heat flux distribution approach for the superheating process is not accurate, as it does not consider the effect of flue gas flow field in the superheater region. These new observations clearly demonstrate the value of the present integrated CFD/1D-PM modeling approach.
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The European Industry: Plenty of Challenges and Opportunities, Paper360º March/April 2020
The European Industry: Plenty of Challenges and Opportunities, Paper360º March/April 2020
Journal articles
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Paptic: Paper Products to Help Save the World, Paper360º March/April 2020
Paptic: Paper Products to Help Save the World, Paper360º March/April 2020
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Editorial: TAPPI Journal 2019 Best Research Paper runner-up focuses on persistent issue of cracking at the fold in coated papers, TAPPI Journal May 2020
ABSTRACT: TAPPI and the TAPPI Journal (TJ) Editorial Board would like congratulate the authors of the runner-up paper to the 2019 TAPPI Journal Best Research Paper Award: Seyyed Mohammad Hashemi Dajan, Douglas W. Bousfield, and Mehdi Tajvidi. Their paper: "Cracking at the fold in double layer coated paper the influence of latex and starch composition," appeared on p. 93 of the February 2019 issue. This coating research was recognized by the TJ Editorial Board for its innovation, creativity, scientific merit, and clear expression of ideas.