Discrete particle simulation of particulate systems: A review of major applications and findings

CFD–DEM simulation of the gas–solid flow in a cyclone separator

Fluidized bed waste incinerators: Design, operational and environmental issues

A sensor system for the study of oil–water flow in pipes is proposed. The purpose is to estimate the area fraction occupied by each fluid in a given section of the pipe, taking advantage of the difference in dielectric permittivity between the fluids. The estimation is done by capacitance measurements between electrodes flush-mounted on the external surface of a nonconductive section of the pipe. A key contribution of the present work is to propose a solution to the problem of capacitive sensing in presence of conductive water which introduces parasitic coupling to stray elements outside the measurement section of the pipe. To this purpose it is proposed a novel sensor configuration that employs guard electrodes, coupled to a tailored electronic interface to drive the guard electrodes and amplify the measurement signal at 2 MHz. The sensor system has been designed, manufactured and tested in an experimental plant where flows of oil–tap water have been generated. The results obtained from the developed sensor system for different fluid fractions have been compared with those obtained by the Quick Closing Valve (QCV) technique adopted as a reference. Differences between the two methods below 3% have been found in the estimations of the normalized oil-area fraction.

A capacitive sensor system for the analysis of two-phase flows of oil and conductive water

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=2653&context=etd

Bed height and material density effects on fluidized bed hydrodynamics

A study of the effect of high inlet solids loading on a cyclone separator pressure drop and collection efficiency

A new technique was developed for measuring the profile and mean velocity of elongated bubbles in horizontal air–water slug flows. It is based on the capacitance between two thin electrodes mounted on the external surface of a dielectric pipe, and has advantages in relation to the traditional parallel wire technique, since it is not intrusive, the presence of impurities in the liquid phase has no influence on the probe response, and it is applicable to very low electrical conductivity liquids, such as oils and deionized water. Tests were performed in an experimental facility with a 5 m long, 34 mm internal diameter Plexiglas pipeline. The elongated bubble mean velocity was determined by using a cross correlation technique applied to the signals coming from two identical capacitance probes, mounted 50 mm distant from each other. The results were compared with an empirical correlation from the literature. Discordance was observed only for flows near the flow pattern transition regions in the flow pattern map.

A non-intrusive probe for bubble profile and velocity measurement in horizontal slug flows

Experiments on the local heat transfer characteristics of a circulating fluidized bed

This work presents experimental information relevant to the combustion of biomass in a bubbling fluidized bed. The biomass distribution in a fluidized bed was studied through tests performed in a cold bed, while the volatiles released in the biomass pyrolysis, the burning rate of the resulting charcoal, and the combustion control regime, were studied through tests performed in a high temperature bed. Visual examination of photographs taken from a transparent walls bed, with a rectangular cross-section, showed that the large fuel particles, typical of biomass processing, were distributed in the bubbles, in the splash zone, and in the emulsion phase. The occurrence of biomass in the emulsion phase was favored by burning biomass particles of greater density and smaller size—experimentally determined in each case. Decreasing the fuel particle size improved the biomass distribution inside the bed. The same was accomplished by increasing the superficial gas velocity as high as possible, compatibly with the acceptable elutriation. Burning tests showed that the biomass fuels have the advantage of reaching the diffusional regime at temperatures that can be lower than 1000 K, which ensures that the biomass fuels burn in a stable regime.

Experimental aspects of biomass fuels in a bubbling fluidized bed combustor

Gas flow through the cake formed over the surface of a filter generates an aerodynamic drag that increases mechanical compression on the layers closer to the filter surface, reducing their thickness and permeability. A procedure was developed to calculate the pressure drop during cake build-up, taking into account the adjustment of the cake properties to the compressive stress through a constitutive equation. The rise of pressure drop with time in a cycle was determined assuming that the gas velocity was constant and that the layers were formed in equal time intervals. Darcy's law, the Happel cell model and the Carman–Kozeny equation were tested in calculating the pressure drop through each layer of filter cake. Part of the particles from the incoming gas stream may settle down before reaching the filter, and not participate on cake formation. Prior knowledge of the settling process was shown to be necessary in order to predict the filter cleaning period, more so when the gas face velocity was lower. Three laboratory filtration experiments, under coal gasification conditions, were used to exemplify the procedure.

Leonardo Goldstein

Papers

A study of the effect of high inlet solids loading on a cyclone separator pressure drop and collection efficiency

A non-intrusive probe for bubble profile and velocity measurement in horizontal slug flows

Experiments on the local heat transfer characteristics of a circulating fluidized bed

Experimental aspects of biomass fuels in a bubbling fluidized bed combustor

A procedure for calculating pressure drop during the build-up of dust filter cakes