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Journal articles
Magazine articles
Open Access
Exergy and sensibility analysis of each individual effect in a kraft multiple effect evaporator, TAPPI Journal October 2019

ABSTRACT: The multiple effect evaporator (MEE) is an energy intensive step in the kraft pulping process. The exergetic analysis can be useful for locating irreversibilities in the process and pointing out which equipment is less efficient, and it could also be the object of optimization studies. In the present work, each evaporator of a real kraft system has been individually described using mass balance and thermodynamics principles (the first and the second laws). Real data from a kraft MEE were collected from a Brazilian plant and were used for the estimation of heat transfer coefficients in a nonlinear optimization problem, as well as for the validation of the model. An exergetic analysis was made for each effect individually, which resulted in effects 1A and 1B being the least efficient, and therefore having the greatest potential for improvement. A sensibility analysis was also performed, showing that steam temperature and liquor input flow rate are sensible parameters.

Journal articles
Magazine articles
Open Access
Kraft pulp bleaching with a P-stage catalyzed by both bicarbonate and TAED, TAPPI Journal July 2019

ABSTRACT: Peroxide bleaching of softwood and hardwood (eucalypt) kraft pulps was performed in solutions of sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3), and sodium hydroxide (NaOH). The conventional P stage (hydrogen peroxide + sodium hydroxide; H2O2 + NaOH) was the most effective brightening system without an additional activator. However, peroxide activation by bicarbonate anion (HCO3•) was obvious in all cases where NaHCO3 or Na2CO3 was used. When N,N,N’,N’-tetraacetylethylenediamine (TAED) was added to the bleaching sys-tem, Na2CO3 as the alkali source afforded equal or slightly higher bleached brightness compared to NaOH usage for both the softwood and hardwood pulps. This outcome is attributed to simultaneous peroxide activation by HCO3• and TAED. When applied to the eucalypt pulp, the H2O2/Na2CO3/TAED bleaching system also decreased the bright-ness loss due to thermal reversion.

Journal articles
Magazine articles
Open Access
Impact of dissolved matter in the oxygen delignifcation stag

Impact of dissolved matter in the oxygen delignifcation stage, TAPPI JOURNAL May 2017

Journal articles
Open Access
New technology for papermaking: Commercializing biopulping, TAPPI JOURNAL, November 1998, Vol. 81(11)

New technology for papermaking: commercializing biopulping, TAPPI JOURNAL, November 1998, Vol. 81(11)

Journal articles
Open Access
Paper science and engineering programs - a comparison of the curricula, TAPPI JOURNAL, October 1998, Vol.81(10)

Paper science and engineering programs - a comparison of the curricula, TAPPI JOURNAL, October 1998, Vol.81(10)

Journal articles
Open Access
High-yield pulping of jack pine, TAPPI JOURNAL, October 1998, Vol.81(10)

High-yield pulping of jack pine, TAPPI JOURNAL, October 1998, Vol.81(10)

Journal articles
Open Access
Optimization of combustion air delivery, TAPPI JOURNAL, September 1998, Vol. 81(9)

Optimization of combustion air delivery, TAPPI JOURNAL, September 1998, Vol. 81(9)

Journal articles
Open Access
Effect of char bed temperature and temperature distribution on fume generation in a kraft recovery boiler, TAPPI JOURNAL, September 1998, Vol. 81(9)

Effect of char bed temperature and temperature distribution on fume generation in a kraft recovery boiler, TAPPI JOURNAL, September 1998, Vol. 81(9)

Journal articles
Open Access
Detailed black liquor drop combustion model for predicting fume in kraft recovery boilers, TAPPI JOURNAL, September 1998, Vol. 81(9)

Detailed black liquor drop combustion model for predicting fume in kraft recovery boilers, TAPPI JOURNAL, September 1998, Vol. 81(9)

Journal articles
Open Access
Characterization of effluents from tcf bleaching of softwood kraft pulp, TAPPI JOURNAL, September 1998, Vol. 81(9)

Characterization of effluents from tcf bleaching of softwood kraft pulp, TAPPI JOURNAL, September 1998, Vol. 81(9)

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