Structured packing maximum operational capacity

This gas rate represents only 53% of the maximum operational capacity at a flow parameter of 0.0400. Therefore, the replacement of the 1-in. Pall Ring packing with Intalox structured packing 2T easily should permit an increase of 50% in the air rate through this scrubber. 

Equation 7-15 also is used to calculate the maximum operational capacity of this structured packing. The values of are taken from Fig-... 

Based on the previous calculations, the use of Intalox structured packing 3T will permit an increase of 45% in the feed rate for the present trayed column. With this packing, the column would operate at 75% of maximum operational capacity at the bottom of the rectifying section. The bottom of the stripping section would run at not more than 87% of maximum operational capacity in order to provide a 15% safety factor. 

Extensive tests on Intalox structured packing 2T have been carried out by the University of Texas at Austin with a system of cyclohexane/n-hep-tane at four different pressures using the same equipment as the previous tests on four other structured packings [18]. This data showed that the maximum capacity (Cg value) of the packing increased as the operating pressure was lowered. 

The maximum operational Cg value at the top of this column (from Figure 7-7) is 0.462 ft/s at a flow parameter of 0.010, after adjustment for physical properties. Thus, the present flow rates in the trayed column can be increased by as much as 65%. The column top, with Intalox Structured packing 2T at 165% rates, will operate at only 87% of the maximum capacity of this structured packing. 

For atmospheric pressure or vacuum distillations, the vapor flow rate is limited by the loss of normal separation efficiency due to entrainment of liquid upward in the vapor phase. The amount of entrainment increases rapidly above a threshold value for the particular system. As the vapor flow rate is increased further, the mass of entrained liquid becomes sufficient to reduce the concentration profile established in the column. The maximum operational Cs has been defined as the greatest vapor flow rate attained before loss of normal separation efficiency. Figures 7-6 and 7-7 give a prediction of the maximum capacity for IMTP random packings and Intalox structured packings, respectively, as limited by liquid entrainment. 

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