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The temporal and cross-sectional distributions of particles in a 127 mm diameter fluidized bed have been obtained using a new generation, high-speed Electrical Capacitance Tomography. Two planes of eight electrodes were used and mounted at 160 and 660 mm from the gas distributor which was a 3 mm thick porous plastic plate made (maximum pore size of 50-70 m). 3 mm diameter, nearly-spherical polyethylene granules made up the bed. Experiments at sampling frequencies of 200-2000 cross-sections per second and gas superficial velocities from just below the minimum fluidization to 83% above minimum fluidization velocities were used. The time series of the cross-sectional average void fractions have been examined both directly and in amplitude and frequency space. The last two used Probability Density Functions and Power Spectral Densities. The information generated show that the fluidized bed is operating in the slugging mode, not surprising given the size of the particles. It has been found that an increase of the excess gas velocity above the minimum fluidization velocity resulted in the increase of the mean void fraction, length and velocity of the slug bubbles as well as the bed height, and in a slight decrease of the slug frequency. The results are presented in a level of detail suitable for comparison with later numerical simulation.

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This paper presents an experimental investigation of the pressure drop (DP) through valves in vertical upward flows. Experiments were carried out using a 1¼″ (DN 32) ball and gate valve. Five opening areas have been investigated from fully open to the nearly fully closed valve, using air with a superficial velocity of 0–3.5 m/s and water 0.05–0.91 m/s. These ranges cover single-phase and the bubbly, slug and churn two-phase flow regimes. It was found that for the single-phase flow experiments, the valve coefficient increases with the valve opening and is the same, in both valves, for the openings smaller than 40%. The single-phase pressure drop increases with the liquid flowrate and decreases with the opening area. The two-phase flow pressure drop was found considerably increased by reducing the opening area for both valves. It reaches its maximum values at 20% opening for the ball valve and 19% opening for the gate valve. It was also inferred that at fully opening condition, the two-phase flow multiplier, for both valves, has been found close to unity for most of the tested flow conditions. For 40 and 20% valve openings the two-phase multiplier decreases in the power-law with liquid holdup for the studied flow conditions. Models proposed originally for evaluating the pressure drop through an orifice in single-phase and two-phase flows were also applied and assessed in the present experimental data.