Graduation date: 1995

Thesis (Ph. D.)--Oregon State University, 1970. / Typescript (photocopy). Includes bibliographical references (leaves 140-145). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1980. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xii, 78 p. : ill. Includes abstract. Includes bibliographical references (p. 76-78).

Black liquor gasification is one of the promising alternatives to eliminate the drawbacks of the conventional recovery unit of the kraft process. A numerical model has been developed to simulate an industrial pilot scale entrained-flow gasifier currently operating at Tampere, Finland. The objective of the model is to investigate the effect of the key operating parameters on the efficiency of sulfate reduction during black liquor gasification. The results of the sensitivity analysis indicates that reduction is dependent of the ratio of the amount of carbon in black liquor to the amount of air being fed into the system, the reactor temperature and the initial particle size. Decreasing the air ratio can improve the efficiency of reduction. The rates of both reduction and carbon gasification increase with increasing in temperature. Higher reduction can be obtained by increasing the initial particle size. However, the values of those parameters need to be optimized based on the desired degree of sulfate reduction and the completion of carbon conversion. Economic considerations such as the length of the gasifier needed to achieve both high reduction efficiency and carbon conversion also need to be considered when selecting operating conditions. / Graduation date: 1994

Up to 2 mg/l of vitamin B₁₂ were produced batch-wise using Propionibacterium freudenreichii on an ammonia based spent sulfite liquor medium in 250 ml Erlenmeyer flasks and a 7-litre benchtop fermentor. The up to 6 gm/l of bacteria utilized the hexoses from the SSL, thus reducing the BOD by 50-80% and producing, as by-products, 3 gm/1 of acetic acid and 7 gm/1 of propionic acid. Pre-treatment of the liquor required stripping of SO₂ to below 200 ppm and adjustment of the pH to between 6.5 and 7.5; precipitation of 1igno-su1fonate was not necessary. It was necessary to add excessive amounts (up to 75 gm/1 dry) of yeast extract or other supplementary nutrient to achieve these vitamin B₁₂ yields. Solutions to this nutrient problem are suggested. The Monod fermentation model whose parameters were estimated using non-linear least squares techniques with dry bacterial cell concentration as the dependent variable, approximate the batch data well. Other less complicated models were not as satisfactory. Estimating the model parameters using linear techniques was most unsatisfactory indeed. Optimum hold-up times for a single stage fermentor for Propionibacteria production, predicted from the Monod model whose parameters were estimated from batch data, were up to 125 hours. These hold-up time extrapolations are subject to large errors. Recommendations for further work on the vitamin B₁₂ process, the extension of the batch modeling work to continuous fermentation and further work on other more suitable microbiological products made from SSL are entertained. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

A magnesium-plus-lime coagulation process, incorporating magnesium recovery by sludge carbonation, recently developed for water treatment has been tested for its application to the decolourization of kraft mill effluents. Total bleached kraft mill effluent (BKME), after biological treatment and effluent from the first caustic extraction stage of a conventional bleachery (E₁ or T-20 effluent) were examined in the laboratory. It was shown that a combination of low magnesium and low lime dosages can achieve better decolourization of kraft mill effluents than 3-5 times as much lime alone, (i.e.: 30-60 mg/1 Mg⁺⁺ plus 375-475 mg/1 lime (as Ca0) at pH ≃11.1 for BKME; and 150-300 mg/1 Mg⁺⁺ plus 1875-3750 mg/1 lime (as Ca0) at pH ≃12.1 for T-20 effluent.) Colour removals of 90-95% were achieved using either fresh or recycled magnesium. Results of the study showed that greater than 90% magnesium recovery can be attained by operating the sludge carbonator to a final pH ≃7.5, with complete mixing and a good C02 diffuser system provided. (Key words: magnesium, lime, kraft mill effluent, decolourization, colour removal, Magnesiurn Carbonate Process.) / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The equilibrium phase diagram for the system sodium sulfate-methanol/water-sulfuric acid at 35° was determined. The nucleation, and growth characteristics of sodium sulfate have been studied in a laboratory scale crystallizer (Mixed Suspension Mixed Product Removal 'MSMPR') under carefully controlled conditions of supersaturation, temperature, agitation rate and residence time. From a statistical analysis of the data it was found that supersaturation, temperature, the interactions of supersaturation with temperature and agitation rate with temperature had positive effects on growth and nucleation rates, while agitation rate, residence time, the interactions of agitation rate with supersaturation, residence time with supersaturation had negative effects on growth and nucleation rates. The 'order' of the nucleation process, b, defined by B = K[sub= N]S[sup= B] was about 5. The growth rate, defined by G = K[sub= G]S[sup= c] Was first order (C = 1). For both processes the activation energy varied from 12 to 15 kcal/mol. The growth process was considered to be surface integration controlled for the various conditions tested. The nucleation rate was considered essentially to be homogeneous nucleation. A non-linear mathematical relationship was developed for both growth rate and nucleation rate in terms of the three factors, temperature, supersaturation and residence time. In both the growth and nucleation rate models the measured data fit poorly. This indicates that the model (a reaction rate type) poorly represents the data for crystallization found in this study. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Black liquor recovery boilers experience significant fire-side fouling problems due to the deposition of entrained particulate matter. Increased understanding of the mechanisms by which particles deposit on these surfaces will lead to more effective management of the resultant problems. There is some evidence which suggests that the sub-micron fraction of this particulate matter deposits by thermophoresis. In an effort to determine conclusively if this is the case, a facility (the Multifuel Combustor at Sandia National Laboratories) was used which could generate and deposit fly ash under conditions that mimic those found in full scale recovery boilers, and dynamically monitor deposit growth rates. Experiments where both the deposit thickness and surface temperature were monitored in situ resulted in linear deposit growth rates despite highly non-linear surface temperature increases. This rules out thermophoresis as the dominant deposition mechanism since it is dependent on the changing thermal driving force. The morphology of the windward side deposit indicates an inertially-dependent mechanism is at work in spite of the size of the particles, which are considerably smaller than what would be commonly considered inertially impacting particles. Leeward side deposits also grow linearly, indicating that thermophoresis, although possibly contributing to deposition, is not the rate-controlling mechanism. Deposition efficiencies fell in the range of 5-15%. The morphology of the sub-micron deposits is highly structured and dendritic in appearance, with over 90% voidage. The particles form long strings or filaments which grow in parallel, indicating that the particles have a high sticking efficiency and do not roll or settle subsequent to impacting. There is minimal contact between adjacent filaments. Recently published research confirms the presence of particles in the 1-50 micron range in recovery boilers. Deposition experiments were performed on this size range as well. Termed Intermediate-size, these particles deposit many times more efficiently, and produce linear deposit growth rates just as the sub-micron particles. They also deposited in clusters of filaments which grew rapidly upward and slowly outward until the adjacent clusters merged. However in this size range the clusters tended to branch out more rapidly than the sub-micron deposits. Deposition efficiencies fell in the range of 40-65%. / Graduation date: 1999

Graduation date: 2004