Acetone Recovery Process

Two methods are prevalent for the recovery of acetone in an acetate dry-spinning plant. One of them is the absorption process and the other, the adsorption one. The latter, having higher recovery efficiency and less steam consumption when employed in rectifying acetone, has come to be more widely used than the former, especially with the improvement in the properties of activated charcoal. But the absorption process has such merits as safety from explosion and possibility of perfectly continuous operation. The lower recovery efficiency, which is one of its drawbacks, can be improved by the circulation of the air laden with vapour. The circulation of the air, together with the use of the multi-stage turboblower and turbine pump helps to increase the thermal efficiency of this process. From this view point, the economical evalution has been made of the absorption process into which several improvements are put by the authors.By the application of a multistage turbine pump, higher coefficient of heat transfer is obtainable between the feed and the wast of the rectifying column.Furthermore, judging from the characteristics of the equilibrium curve of rectification, there is little difference between the two methods with regard to their construction costs of equipment and their consumption amount of calorific power, when the density of the feed is kept over 2.5% in weight, although, in this case, cool water at the temperature of 5°C or so is required for absorption use.The construction cost of the equipment can be much more reduced and the power required in the operation, much more saved, when the said cool water is supplied directly refrigerated with liquid ammonia.As to the circulating air, the power of the blower will be used effectively both for promoting the efficiency of the heat exchanger and for heating the air by increasing the compression ratio.Table 1 shows the comparison between the old and the new absorption processes with respect to the utility and the construction cost, and Table 3, the results of the actual operation carried out in the authors' plant.