Packings IMTP - pressure drop

Figure 9-21G. Generalized pressure drop correlation for non-foaming systems for IMTP metal random packing. Parameter of curves is pressure drop in inches of water/foot packed height. Numbers in parentheses are mm of water/meter of packed height. Used by permission of Norton Chemical Process Products Corp., Bull-IHP-1, 12/91 (1987).

Figures 9-21F and 21G (for Norton s IMTP packing only) can be up to 20% higher than industrial experience for the same Cj values at a flow parameter (FP) of 0.01 [82]. At an absolute colunrn pressure of 10 mm Hg or less, the pressure drop actual can be up to 30% lower than that read from the Figure 9-21F at the FP of 0.01 and the same Cg value [82]. The conclusion is that the generalized correlation, Figures 9-2IF and -21G always give a conservative design AP at operating pressures less than 70 mm Hg abs. Several other factors must be considered, such as variability of gas and liquid rates and densities or specific volumes.

For high pressure distillation of light hydrocarbons, industrial performance indicates that the pressure drop actually obtained is about two times that predicted by the use of the GPDC charts. Figure 9-21F and 9-21G (for Norton s IMTP packing only). When the vapor density is at least 6% of the liquid density, the actual pressure drop is expressed [82] ... 

Pressure drop equation For IMTP packing, non-foaming system, use Figure 9-21G or I. 

Read, F, for the approximate calculated Cs, ft/sec from Table 9-37 at calculated liquid rate, Ib/hr-ft. Then read Y from IMTP Packing Pressure Drop chart. Figure 9-2IG and then read curves showing pressure drop, (may require interpolation). 

In distillation, maximum operational capacity (sometimes called efficient capacity because of the nature of the definition) is determined by the amount of liquid entrainment required to reduce separation efficiency (see Chapter 7). Data of Strigle and Rukovena for IMTP, metal Pall Ring, and ceramic Intalox saddle packings indicate that the pressure drop at maximum operational capacity is [11] ... 

The volumetric heat transfer coefficients for 70 IMTP packing are about 70% greater than those for grid structures that previously have been used to provide low pressure drop in some of these columns. The 40 size of IMTP packing can provide over twice the volumetric heat transfer coefficient of grids under the same vapor and liquid flow rates. Normally, packings smaller than H4-in. size are not used in heavy hydrocarbon service. 

Thus, the 50 IMTP packing can revamp the trayed column to obtain a 55% increase in capacity at the same separation efficiency. The total pressure drop through the packed column is only 42 mm Hg, even at a 55% higher feed rate. This is only about one-half the pressure drop through the 26 valve trays at the present lower flow rates. Further, the reduced pressure at the bottom of the column enhances the stripping action and lowers the bottom column temperature. 

The comparisons of the mvest pl jraddngs show also that the pressure drop of IMTP 40 is higher with 3S% and mote than those of RSR No 0.7 and RSR No 1. The specific surface ar of IMTP 40 is between these of die two RSR puskings used for comparison. Similar r iults are obtained by the comparison between the packings IMTP SO and RSR l.S. 

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