About TAPPI Journal
An internationally recognized technical publication for over 60 years, TAPPI Journal (TJ) publishes the latest and most relevant research on the forest products and related industries in digital format. A stringent peer-review process and distinguished editorial board of academic and industry experts set TAPPI Journal apart as a reliable source for impactful basic and applied research and technical reviews. TAPPI Journal is going Open Access. Read more.
Guest Editorial: Fifty years with TAPPI: A personal and professional perspective, TAPPI Journal June 2020
June 01, 2020
ABSTRACT: While reflecting on this being my 50th year in TAPPI, it dwaned on me that my father Murray must also have been a TAPPI member for a similar length of time and that he probably joined TAPPI for the same reasons--we both had just started our first jobs in the pulp and paper industry and wanted to learn ecerything we could about the underlying technology.
Cationic emulsions of maleic anhydride derivatives of oleic and abietic acid for hydrophobic sizing of paper, TAPPI Journal 2020
June 01, 2020
ABSTRACT: Ordinary rosin sizing agents are mixtures of resin acids that include abietic acid and related compounds obtained from softwoods such as pine. Fatty acids, which are another byproduct of the kraft pulping of soft-wood species, also may have hydrophobic effects, but their use as sizing agents has seldom been considered. In the current study, abietic acid and oleic acid, in the absence of other components, were first modified by reaction with maleic acid anhydride. Then, the maleated derivatives (maleated oleic acid [MOA] and maleated abietic acid [MAA]), which were emulsified with cationic starch at the 1:1 and 3:2 ratio, respectively, were added to fiber furnish containing aluminum sulfate (papermaker’s alum). The prepared sheets were dried with a rotating drum on one side at 100°C at low pressure to cure the sizing agents. The chemical, optical strength, and absorption properties were measured. The presence of the sizing material was confirmed using time of flight secondary ion mass spectrometry (ToF-SIMS), and the retention of the sizing agent on fibers was supported by evidence of hydrocarbons on the paper surface. In addition to achieving sufficient water resistance features with MAA, a lesser hydrophobic character was obtained when using MOA. Compared to commercial applications, relatively large amounts of sizing agent were used to obtain a sufficient sizing degree. The MOA required 5% addition to achieve a similar sizing degree as MAA at the 2% level. The sizing treatments also resulted in substantial increases in tensile index value. Since cationic starch was used in the formulation of the sizing agents, the increase in tensile index may have been due to the influence of cationic starch. Contributions to paper strength from a combination of ionic complexation and mutual association of hydrophobic groups is also proposed. Depending on the amount of sizing agent, the yellowness increased, especially when sizing with MOA.
Development of a fast brightness testing method for mechanical pulp based on microwave oven drying, TAPPI Journal June 2020
June 01, 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.
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
June 01, 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.
Case study: Paper mill power plant optimization—balancing steam venting with mill demand, TAPPI Journal June 2020
June 01, 2020
ABSTRACT: Most Power departments are tasked with generating steam to support mill wide operations, generate electricity, and reduce operating costs. To accomplish these tasks, power boilers generate high pressure steam that is reduced to intermediate and low pressures for process utilization in the mill by means of steam turbine generator extraction or pressure reducing valves. The most economical method to reduce steam pressure is the use of steam turbine generators, as electricity is generated from the steam when it is reduced in pressure. Electricity that is produced by these generators provides a substantial financial benefit and helps offset overall operational costs. To achieve tangible financial gains, the mill must evaluate the overall cost of steam production and the price of electricity.The current work provides a case study of power plant optimization that evaluated electricity production and steam production costs balanced with mill steam demand. Process and cost optimization led to a significant reduc-tion in low pressure steam venting, resulting in reduced fuel consumption and reduced operating cost.