Thesis (doctoral)--Göteborg University, 2006. / Includes bibliographical references.

A pilot scale fluidized bed biomass gasifier developed at Texas A&M University in College Station, Texas was instrumented with thermocouples, pressure transducers and motor controllers for monitoring gasification temperature and pressure, air flow and biomass feeding rates. A process control program was also developed and employed for easier measurement and control. The gasifier was then evaluated in the gasification of sorghum, cotton gin trash (CGT) and manure and predicting the slagging and fouling tendencies of CGT and manure. The expected start-up time, operating temperature and desired fluidization were achieved without any trouble in the instrumented gasifier. The air flow rate was maintained at 1.99 kg/min and the fuel flow rate at 0.95 kg/min. The process control program considerably facilitated its operation which can now be remotely done. The gasification of sorghum, CGT and manure showed that they contained high amounts of volatile component matter and comparable yields of hydrogen, carbon monoxide and methane. Manure showed higher ash content while sorghum yielded lower amount of hydrogen. Their heating values and gas yields did not vary but were considered low ranging from only 4.09 to 4.19 MJ/m3 and from 1.8 to 2.5 m3/kg, respectively. The production of hydrogen and gas calorific values were significantly affected by biomass type but not by the operating temperature. The high values of the alkali index and base-to acid ratio indicated fouling and slagging tendencies of manure and CGT during gasification. The compressive strength profile of pelleted CGT and manure ash showed that the melting (or eutectic point) of these feedstock were around 800 degrees C for CGT and 600 degrees C for manure. Scanning electron microscopy (SEM) images showed relatively uniform bonding behavior and structure of the manure ash while CGT showed agglomeration in its structure as the temperature increased. The instrumentation of the fluidized bed gasifier and employing a process control program made its operation more convenient and safe. Further evaluation showed its application in quantifying the gasification products and predicting the slagging and fouling tendencies of selected biomass. With further development, a full automation of the operation of the gasifier may soon be realized.

Produced water and spent drilling fluids from petroleum operations represent a significant expense to companies developing new energy reserves. These spent fluids, seldom recycled, offer a viable source of water resources for oil-field reuse. A major obstacle to reuse is the presence of suspended solid material in the fluids. Such contaminants, if not removed, will not only prevent any reuse but will also impede disposal. The objective of this project was to evaluate membrane filtration as a way to remove suspended and entrained particles to produce re-useable effluents using membranes. Ceramic and Polyvinylidene Flouride (PVDF) hollow fibre membranes were used in laboratory scale experiments in the investigation of the colloidal filtration of field produced spent drilling fluids and produced water. Feed parameter and operational parameter evaluation of ceramic and PVDF hollow fibre membrane filtration of spent drilling fluids and produced water showed that feed concentration, solids in the spent drilling fluid and oil in the produced water, is the most important parameter during membrane filtration. Operational parameter variation showed that high cross flow velocity was beneficial in flux maintenance during spent drilling fluid filtration due to its high solids concentration because of the scouring effect on the cake layer on the membrane surface. Pressure regimens were important in flux decline as relatively high pressures accelerate the consolidation of the concentration polarization layer causing flux decline. High temperatures were generally beneficial for increased flux in the filtration of produced water and spent drilling fluids. Resistance calculations were used to deduce the contribution of individual resistances during the ceramic filtration of produced water and spent drilling fluids and were identified as a real-time tool for monitoring membrane integrity and fouling. Backwashing as a fouling mitigation technique was effective in flux maintenance in ceramic membranes especially in the filtration of produced water; cleaning solutions were effective in flux recovery in ceramic membrane filtration and to a slightly lesser degree in hollow fibre membrane filtration. A methodology in determining the suitability of water based oil field wastes using membranes was developed to help future investigations of this type.

Univ., Diss.--Göteborg, 2006. / Enth. außerdem 5 Zeitschriftenaufsätze.

No description available.

An ash monitoring system prototype that consists of a “clean” heat flux sensor and a “dirty” heat flux sensor was developed in this study. The “clean” heat flux sensor was studied numerically and experimentally while the “dirty” heat flux sensor was tested in the experiment. Two different measurement methods were applied on the “clean” sensor, one from the original study and one proposed in the present work. The new method required additional data processing procedures to be able to work in an on-line basis. Among the three data processing procedures developed in this study the central temperature difference procedure was found to be the most reliable one. Numerical results provided valuable information about the heat transfer pattern at the sensing element and also the performance of the sensor at high radiation heat flux levels. A rough calibration of both “clean” and “dirty” heat flux sensors was conducted experimentally. Nevertheless, the experimental results still served as a primary assessment for both sensors. Observed disagreements between the original study and the present one were probably caused by the modification of the sensor structure made in the present study. Sensitivity variation at high heat flux levels did not appear in the numerical results of either measurement method. Low overall sensor temperature change was believed to be the main reason as it meant less change in thermal properties of the sensing disc. Although the results of the study suggested that the proposed oscillation method was less attractive than the original one, it increased the possibility of resolving the surface characteristic variation problem that was considered crucial for the performances of the “clean” heat flux sensor regardless of the measurement method used. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-09-03 16:38:26.48

No description available.

No description available.

Thesis (Ph. D.)--Oregon State University, 1990. / Typescript (photocopy). Includes bibliography (leaves 230-239). Also available via the World Wide Web.

Thesis (M.S.)--Naval Postgraduate School, 1966. / Thesis advisor(s): Haderlie, Eugene C. Cover title. "October 1966." Includes bibliographical references (p. 48-50).