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The effect of diminished pressure on the efficiency of packed fractionating columns has been investigated in a 0.75-inch glass column packed with Raschig rings, Fenske stainless steel helices, Cannon pertruded packing, and McMahon wire gauze saddles. Column efficiency was found to vary little with pressure, being slightly higher at 50 and 100 mm. of mercury absolute pressure than at 10, 20, or 730 mm. of mercury.In addition to efficiency tests on the four packings, vapor-liquid equilibrium data and correlations of holdup and pressure drop are reported.

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Sulfur removal during combustion of coal or low-temperature coal char using excess air in a fluidized bed of dolomite has been demonstrated in a continuous benchscale unit. The SO 2 produced during the combustion is fixed as CaSO4 by reaction with CaO in the dolomite as follows: CaO + SO 2 + Yz O 2 = CaSO 4. The ranges of conditions explored were calcium oxide-to-feed sulfur mol ratios in the range of 1 to 8, fluidizing velocities of 1.5 and 3.0 ft/sec, superficial gas residence times of 1 and 2 sec, and temperatures from 1700° to 1900°F, with 120% stoichiometric air at the operating pressure of 8 psig. The process was operable at all conditions studied using a highly caking Pittsburgh seam coal as well as two low-temperature chars. Desulfurization efficiency with a Ca-to-S mol ratio of 1 was 78%; at Ca-to-S ratios of 2 or higher desulfurization efficiency exceeded 90%. Continuous regeneration of the sulfated dolomite using partial combustion of carbon monoxide gas at 1950°F was also demonstrated. As high as 97% of the sulfur in the dolomite was liberated as SO 2 by this treatment giving a gas that contained SO 2 concentrations as high as 23 times that in the combustion gases. Dolomite life was investigated, with the dolomite subjected alternately to SO 2absorption during combustion and subsequent regeneration. It was demonstrated that by regeneration and re-use of the dolomite, the ultimate SO 2 capacity can be extended in excess of four times that for a once-through process. Regeneration also permits recovery of elemental sulfur by processing the SC>2-rich regenerator off-gas.