Bubble Column Reactor
It has been constructed in a narrow slit geometry which reproduces existing data from the literature on non foaming systems and cylindrical bubble columns. Ths slit geometry allows us to observe the flow pattern and to determine the presence of foam. The superficial gas velocity Ug and liquid velocity Ul are prescribed data which we control. The total average gas fraction in steady flow is determined by direct measurement of the liquid volume fraction after the gas and liquid flow are simultaneously stopped. Steady states are recognized by visual observation of the foam interface. When particles are present in the reactor, the total average gas fraction becomes where is the solids volume fraction.
We used a 0.06% wt. SDS plus 1.0% wt. 1-Butanol in water solution. This solution was usually prepared the same day or the day before the tests were carried out to assure maximum freshness and a standard foaminess. This property of the solution was measured at the beginning and after each test and did not show any significant change; the mean value of the foaminess is 0.85. This foaming system reproduces the CANMET process as shown in the following figure.
Gas holdup as a function of gas velocity, for a 0.06% wt. SDS + 1.0% wt. 1-Butanol solution at a liquid velocity of 0.154 cm/s (red, solid circles) and the CANMET process, which liquid velocities are in the range 0.1 - 0.2 cm (blue, open circles).
We used hydrophobic and hydrophilic versions of two different kinds of sands. One of them was provided by Science Kit & Boreal Laboratories and the other one by STIM-LAB. In both cases, hydrophobic particles were obtained by treating the surface of ordinary sand, which happens to be hydrophilic. Science Kit & Boreal Laboratories treated theirs with very reactive chlorinated silanes. On the other hand, at STIM-LAB, they coat their sand with a very thin layer of resin, which does not wash away.
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