Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 295-300). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xix, 168 p.; also includes graphics (some col.) Includes bibliographical references (p. 159-168). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xxvii, 334 p.; also includes graphics (some col). Includes bibliographical references (p. 322-334). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--Washington State University. / Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains ix, 133 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 103-114).

Thesis (M.S.)--Ohio State University, 1985. / Includes bibliographical references (leaves 93-95). Available online via OhioLINK's ETD Center

A bench-scale, two-dimensional multi-compartmentalized fluidized reactor was designed and studies of hydrodynamic behavior of fluidization of struvite pellets were performed. Also size growth distribution tests were analyzed qualitatively. The study validated a previously-proposed theory, concerning the relationship between dynamic pressure drop and upflow velocity as well the experimental protocol to determine the minimum fluidization velocity. Findings indicated that the mixture of two-sized particles would behave rather independently of each other, before the bed expansion. It was suggested that bed height measurement could be another promising method to pinpoint minimum fluidization velocity as there is a sharp bed surface "waking episode" during the process of a packed bed being gradually fluidized. Bed expansion equations for the prediction of void fraction as a function of superficial upflow velocity or vice versa, have been established for 4 groups of monosize particles, as well as two mixtures of two-sized particles. The equation constants did not agree well with previously established ones. The two layers of segregated mixture bed had congruent linear relationships between the logarithmic void fraction and logarithmic upflow velocity. It was found that a mixture does not always go through segregation, but only when the size difference is large enough. Size growth distribution tests were performed under different hydrodynamic configurations as well as seeding conditions. Conclusions can be made that a bed with uniformly- distributed particle void fractions and higher mixing energy input (upflow velocity), normally has better performance of struvite growth in size. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

No description available.

Due to the nature of gas-solid fluidized beds, providing continuous contacts between fluidizing particles and between particles and the reactor wall, the occurrence of electrostatic charges is unavoidable. In the polyethylene industry, electrostatics is a major problem. Large amounts of electrostatic charges are generated causing polyethylene and catalyst particles to adhere to the reactor wall, forming sheets. Particle sheets can break off and block the distributor plate, causing long shutdown periods for clean-up which result in economic loss due to decreased production and higher maintenance costs. The overall purpose of the project of which this thesis is part of is to help industry in minimizing this problem by examining the mechanisms underlying this phenomenon. Towards this goal, an experimental technique for the measurement of the degree of wall fouling and its charge distribution was previously developed and implemented in an atmospheric system with a column of 0.102 m in diameter. This technique was extended in this thesis to a pilot-scale unit (0.154 m in diameter) designed to be capable of operating at pressures and temperatures up to 2 600 kPa and 100°C respectively and gas velocities up to 1 m/s, which are operating conditions of industrial polyethylene reactors. Preliminary experiments showed that increasing the operating pressure from 101 kPa to 401 kPa almost doubled the amount of polyethylene wall fouling due to the higher bubble rise velocity at this pressure, enhancing charge generation within the fluidized bed. Changing the particle size distribution by removing particles smaller than 250 μm had no significant effect on the extent of the wall fouling. Increasing the column diameter from 0.102 m to 0.154 m decreased wall fouling due to the lower column wall area per mass of particles. Overall, particle-particle contacts generated positively and negatively charged particles, but did not produce a net charge in the bed due to the negligible elutriation. However, particle-wall contacts produced a net charge. The formation of the wall layer was due to the image force created by the net charge and the layering effect created by the attraction between oppositely charged particles.

Three different Western Canadian coals were gasified with air and steam in a fluidized bed of 0.73 mm Ottawa sand and coal, at atmospheric pressure, and temperatures of 1023 - 1175 K to produce a low Btu gas. The coals tested were of two types: one non-caking and two caking coals. The results were compared with those previously obtained for the same three coals when gasified in essentially the same equipment, but operated as a spouted bed. The effects of temperature, coal feed rate, air to coal ratio, steam to coal ratio, coal quality, coal particle size, and bed depth on the gas composition, gas calorific value and the operating stability of the gasifier, were established by running gasification tests over a wide range of operating conditions. Typical calorific value of the gas obtained for all three coals was in the range of 2.0 - 2.6 MJ/m³, which is lower than reported for the spouted bed and commercially available fluidized bed gasifiers. Analysis of the results suggested that in the present low temperature gasifier, the combustion and pyrolysis reactions predominate over the gasification reactions. The ability to treat caking coals in fluidized bed and spouted bed reactors is discussed. It is concluded that the dispersion of coal in a bed of inert silica and ash, rather than hydrodynamic characteristics is the key-factor in their success in handling caking coals. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Unknown