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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.
Journal articles
Magazine articles
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.
Journal articles
Magazine articles
Effects of a PFI refiner’s operational parameters on the swellability of recycled fiber, TAPPI Journal May 2020
ABSTRACT: This paper presents data on the effects of operational parameters (number of revolutions, linear pressure, and gap) of the PFI refiner on the swellability of recycled fiber, which was characterized by water retention value (WRV). The results showed that the increase of recycled fiber’s WRV was proportional to the number of revolutions and the linear pressure, but inversely proportional to the gap. The mathematical relation between these parameters and the fiber WRV could be described by an empirical model for gaps greater than 0.1 mm. Scanning electron microscopic images of fiber morphology showed that the basic framework of fibers could be maintained with the gap greater than 0.1 mm, but was destroyed with smaller gaps. This model provides a technical reference for quantitative control of refining treatment and an effective method for improving recycled fiber quality.
Journal articles
Deinking of high-quality offset papers: influence of consistency, agitation, speed, and air flow rate in the flotation stage, TAPPI JOURNAL, March 1999, Vol. 82(3)
Deinking of high-quality offset papers: influence of consistency, agitation, speed, and air flow rate in the flotation stage, TAPPI JOURNAL, March 1999, Vol. 82(3)
Journal articles
Liquor-to-liquor differences in combustion and gasification processes: nitrogen oxide formation tendency, TAPPI JOURNAL, March 1999, Vol. 82(3)
Liquor-to-liquor differences in combustion and gasification processes: nitrogen oxide formation tendency, TAPPI JOURNAL, March 1999, Vol. 82(3)
Journal articles
A guide to developing a best management practices (bmp) plan for spent liquor - part 1, TAPPI JOURNAL, October 1999, Vol. 82(10)
A guide to developing a best management practices (bmp) plan for spent liquor - part 1, TAPPI JOURNAL, October 1999, Vol. 82(10)
Journal articles
Troubleshooting gear drives, TAPPI JOURNAL, October 1999, Vol. 82(10)
Troubleshooting gear drives, TAPPI JOURNAL, October 1999, Vol. 82(10)
Journal articles
NMR studies, part 5: nature of residual lignin in kraft pulps, TAPPI JOURNAL, September 1999, Vol. 82(9)
NMR studies, part 5: nature of residual lignin in kraft pulps, TAPPI JOURNAL, September 1999, Vol. 82(9)
Journal articles
Impulse drying: status of the pilot-scale research program, TAPPI JOURNAL, September 1999, Vol. 82(9)
Impulse drying: status of the pilot-scale research program, TAPPI JOURNAL, September 1999, Vol. 82(9)
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)