Thesis (Ph. D.)--Institute of Paper Science and Technology, 1990. / Bibliography: leaves 125-128.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1982. / Bibliography: leaves 77-81.

Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2005. / Empie, Jeff, Committee Chair ; Banerjee, Sujit, Committee Member ; Deng, Yulin, Committee Member. Includes bibliographical references.

Thesis (M.S.)--Institute of Paper Chemistry, Lawrence College, 1939. / Includes bibliographical references (p. 75-77).

The purpose of this investigation was to continue the color reduction study of alum treatment of caustic wash from chlorine bleached kraft pulp, to determine if a double tray Dorr thickener could be used to settle the coagulated waste, and to determine if a centrifugal separator could be used to dewater the sludge from the Dorr underflow. Approximately 5000 gallons of caustic wash from chlorine bleached kraft pulp was used for each phase of this investigation. The raw waste feed flow rate was varied from 1750 pounds per hour to 2499 Pounds per hour. The alum slurry flow rate was varied from 39 Pounds per hour to 60 pounds per hour. The hydrochloric acid flow rate remained constant at approximately five pounds per hour. The raw waste was acidified with 38 percent hydrochloric acid to a pH of 6.0, and treated with alum sulfate slurry to coagulate the solids in the waste. The coagulated solids were concentrated in a double tray Dorr thickener. The percent of insoluble solids in the Dorr underflow varied from 0.65 to 1.35. The concentrated solids were fed to a Merco centrifugal separator where the insoluble solids were concentrated in approximately equal proportions in the Merco overflow and underflow. / Master of Science

A computational model is developed to investigate fundamental flow physics and transport phenomena of evaporating wavy-laminar falling liquid films of water and black liquor. The computational model is formulated from first principles based on the conservation laws for mass, momentum, energy and species in addition to a phase transport equation for capturing interface deformation and evolution. Free surface waves are generated by monochromatic perturbation of velocity. Continuum models for interfacial evaporation define source terms for liquid vaporization and species enrichment in the conservation laws. A phenomenological crystallization model is derived to account for species depletion due to salt precipitation during black liquor falling film evaporation. Using highly resolved numerical grids on parallel computers, the computational model is implemented to analyze the dynamics of capillary separation eddies in low Reynolds number falling films, investigate the dominant mechanisms of heat transfer enhancement in falling films at moderately high Reynolds numbers and study the fundamental wave structures and wave induced transport in black liquor falling films on flat and cylindrical walls. From simulation results, a theory based on the dynamics of wavefront streamwise pressure gradient is proposed to explain interfacial waves interaction that give rise to multiple backflow regions in films dominated by solitary-capillary waves. The study shows that the mechanism of heat transfer enhancement in moderately high Reynolds number films follows from relatively lower conduction thermal resistance and higher crosswise convective transport at newly formed intermediate wavefronts. Interfacial phenomena such as wave-breaking and vapor entrainment observed in black liquor falling films is explained in terms of a mechanistic theory based on evolution of secondary instabilities and large amplitude wave force imbalances.

Environmental concerns and cost reduction have been the focus of pretreatment and extended delignification in Kraft pulping for some time now. Previous work has looked at the diffusion of tritiated water into softwood chips. This thesis looks at the diffusion of Na2S into southern pine softwood chips. Two size fractions were used. The measured diffusion data were compared to the equilibrium of mixing between the HS ion and water alone. Since pine is porous, effective diffusivities were calculated for each size fraction using a 1-dimensional model. Tortuosities were then calculated for the HS / pine wood system. These diffusivities are compared to values previously obtained for tritiated water.

Gasification of black liquor is an alternative to the combustion of black liquor, which is currently the dominant form of chemical recovery in the paper industry. Gasification of black liquor offers the possibility of higher thermal efficiencies than combustion, reducing manufacturing costs and creating new revenue streams through a forest biorefinery. Pressurizing the gasification reactor further enhances the efficiency advantage of gasification over combustion. This study uses a pressurized entrained flow reactor (PEFR) to study black liquor gasification behavior under pressures, temperatures, and heating rates similar to those of next-generation high-temperature black liquor gasifiers. The effects of pressure on black liquor char morphology, gasification rates, pyrolysis carbon yields, and sulfur phase distribution were studied. These characteristics were investigated in three main groups of experiments at 900oC: pyrolysis (100% N2), gasification with constant partial pressure (0.25 bar H2O and 0.50 bar CO2), and gasification with constant mole fraction (10% CO2, 2% H2O, 1.7% CO, 0.3% H2), under five, ten, and fifteen bar total pressure. It was found that pressure had an impact on the char physical characteristics immediately after the char entered the reactor. Increasing pressure had the effect of decreasing the porosity of the chars. Pressure also affected particle destruction and reagglomeration mechanisms. Surface areas of gasification chars decreased with increasing pressures, but only at low carbon conversions. The rate of carbon conversion in gasification was shown to be a function of the gas composition near the particle, with higher levels of inhibiting gases slowing carbon conversion. The same phenomenon of product gas inhibition observed in gasification was used to explain carbon conversions in pyrolysis reactions. Sulfur distribution between condensed and gas phases was unaffected by increasing total pressure in the residence times investigated. Significant amounts of sulfur are lost during initial devolatilization. With water present this gas phase sulfur forms H2S and did not return to the condensed phase.

In a three year study, the applicability of the cortisol response to capture as a biomarker of the health of fish from areas chronically exposed to pollution was assessed. Northern pike (Esox lucius) and yellow perch (Perca flavescens) captured from an area contaminated by bleached kraft pulp mill effluent (BKME) were initially found to be incapable of elevating their blood cortisol concentration to reference levels. Following a reduction of the amount of absorbable organochlorines (AOX) in the BKME, fish downstream of the mill regained their normal cortisol response to capture. The time frame for this recovery was from between 6 to 18 months. Fewer young fish downstream of the effluent provided evidence for the impact of long-term exposure to BKME at the population level. / The impairment of the cortisol response to capture, and its subsequent recovery after effluent reduction provide the foundation for developing cortisol as a biomarker of contaminant exposure. Further work should determine the relationship between cortisol and the effect at higher levels of biological organization (e.g., population and community).

No description available.