A selective combination of the principles of a thermal mass flow meter and constant temperature anemometry was used to develop a solid mass flow meter that improves significantly on the flow meter developed by De Vos et al (2010). The flow meter has a measurement plate that is kept at a constant temperature. Due to conductive heat transfer between the entrained solids and the measurement plate, additional power is needed to maintain the plate at this setpoint temperature value. This additional power was correlated against the average solids flow rate. The calibration curve shows a linear relationship between the power measurement and the entrainment flux for entrainment fluxes between 3.4 x 10-4 kg/(m2.s) and 7.5 x 10-3 kg/(m2.s). Deviation from a linear response at lower entrainment fluxes may be caused by a longer residence time of fine particles on the measurement plate due to lower shear forces. At higher entrainment fluxes the power measurements were unreliable due to poor temperature control. The turndown ratio of the linear section of the calibration curve is approximately 3 times that of the linear part of the calibration curve of the flow meter developed by De Vos et al (2010). Even further improvement is possible with better temperature control. In a case study to test the applicability of the flow meter to measure changes in entrainment rate associated with hydrodynamic properties other than a change in gas superficial velocity, small amounts of ethanol were dosed to the inlet air. The continuously measured entrainment rate increased at lower ethanol dosing rates but decreased as the dosing rate of ethanol was increased. The increase in entrainment rate may be explained by a reduction in static electricity in the bed, while the decrease at higher dosing rates may be as a result of increased powder cohesivity. / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted

Oxy-combustion is a process which removes nitrogen from air prior to combustion in order to produce a high concentration of CO2 in the exhaust. This enables CO2 liquefaction, transport, and storage to greatly reduce CO2 emissions to the atmosphere. Atmospheric oxy-coal combustion has been successfully demonstrated at industrial scales and could be retrofit in existing coal boilers, but thermodynamic efficiencies are low and therefore uneconomical. Pressurized oxy-coal combustion has the potential for higher efficiency and lower cost but requires new technologies related to the coal feed system, the burner, and ash management. This project describes work needed to complete the dry feed pressurized oxy-coal combustor (POC) at BYU. The POC required the software control system (OPTO22) to be completed, a reactor shakedown, and testing of a previously designed burner by recording reactor thermocouple, exhaust concentration, and radiometer measurements. The following has been successfully demonstrated: 1) reactor heat-up with natural gas 2) coal combustion within temperature limits of the reactor 3) slagging that allows ash management.

No description available.

A cold flow model circulating fluidized bed reactor was designed and built to determine any correlation that may exist between the percentage of fine bed material in the overall reactor inventory, and both the solids circulation rate as well as the riser axial particle distribution. It was determined that for Geldart group B particles (sand), there may be a direct relationship between an increase in the percentage of fine particles and an increase in the solids circulation rate for a given riser superficial velocity. There may also be a direct relationship between the percentage of fine particles and an increase in the overall solids concentration in the upper zones of the riser for a given riser superficial velocity. It is theorized that these effects are due to a reduction in the overall mean particle size of any particle clusters formed due to the increase of the percentage of fines.

Yes / The fluidized bed coating system is a conventional process of particles coating in various industries. In this work, an experimental investigation was conducted using Response Surface Methodology (RSM) to optimize the coating mass of particles in a top-spray fluidized bed coating. The design of experiments (DOEs) is a useful tool for controlling and optimization of products in industry. Thus, DOE was conducted using MINITAB software, version 16. This process used a sodium silicate solution for coating the sodium percarbonate particles. The effect of the fluidization air flow rate, atomization air flow rate and liquid flow rate on the coating mass in the top-spray fluidized bed coating was investigated. The experimental results indicated that the coating mass of particles is directly proportional to the liquid flow rate of the coating solution and inversely proportional to the air flow rate. It was demonstrated that the flow rate of the coating solution had the greatest influence on the coating efficiency. / Metallic Material Processing Research Group, ACECR, Branch of Tehran University, Tehran, Iran.

M. S.

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