Slurry density variations

Slurry Density Variations. The model was also used to simulate the slurry oxidations with different initial conditions. Initial pH s of 4.5 and 5.5 were both tested. Results (total concentration and solution phase concentration curves) for the initial pH 4.5 are presented in Figure 9. By using the predicted mass transfer coefficient and rate constants, the computer curves can match these experimental results very well. 

Closely connected with control of the flow properties of Slurries is control of their density. For a given compn considerable variation in Slurry d can be achieved by introduction of small amounts of porous solids by air entrapment (aeration) and by inclusion of small amounts of gas producing ingredients. It is the latter approach (ie, gas-formers) that is... 

The first three columns of Table 10.1 show a sieve-screen analysis of a 100-cc (0.0001-m3 or 0.0035-ft3) slurry sample. The crystals are cubic and have a solids density ps of 1.77 g/cc (110.5 lb/ft3). Calculate the crystal size distribution n of the solids, the average crystal size, and the coefficient of variation of the crystal size distribution. 

An important aspect of the design of three phase bubble columns is the variation of catalyst distribution along the reactor height, and its effect on reactor performance. Many factors influence the degree of catalyst distribution, including gas velocity, liquid velocity, solid particle size, phase densities, slurry viscosity, and, to a lesser extent, column diameter, solid shape and chemical affinity between the solid and liquid phases. 

CSIRO Minerals has developed a particle size analyzer (UltraPS) based on ultrasonic attenuation and velocity spectrometry for particle size determination [269]. A gamma-ray transmission gauge corrects for variations in the density of the slurry. UltraPS is applicable to the measurement of particles in the size range 0.1 to 1000 pm in highly concentrated slurries without dilution. The method involves making measurements of the transit time (and hence velocity) and amplitude (attenuation) of pulsed multiple frequency ultrasonic waves that have passed through a concentrated slurry. From the measured ultrasonic velocity and attenuation particle size can be inferred either by using mathematical inversion techniques to provide a full size distribution or by correlation of the data with particle size cut points determined by laboratory analyses to provide a calibration equation. 

Continuous crystallizers must operate steadily at equilibrium to achieve the design requirements. This means the feed rate, production rate, slurry density, operating temperature, liquid level, and so on, should held constant as a function of time. To accomplish this result requires the crystallizer to be isolated from upstream or downstream variations and the instruments need to be continuously calibrated. To help accomphsh this objective, a 12- to 24-hour agitated feed tank needs to be installed before the crystallizer. 

The other extreme of slurry behavior in a horizontal pipe, heterogeneous flow, is characterized by a pronounced variation in the local solids concentration with position in the pipe. The particle settling velocity in this case is high. This implies that the density of the solid particles is higher than the working fluid, for example, sand-water slurry... 

Rohani et al. (1990) postulated that it may be desirable to maintain the fines slurry density at some constant value over a batch run. They experimentally realized an improvement of the final CSD (larger mean size and smaller coefficient of variation) by using a conventional PI controller that manipulated the fines destruction rate to maintain a set point for the fines slurry density. Rohani and Bourne (1990) used simulations to demonstrate a selftuning regulator to be more effective in set-point tracking and disturbance rejection than the PI controller. 

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