Capacity
iC4/nC4 100 psia (6.9 bar) -- The operational diagram is presented in Figure 4 for the 100 psia (6.9 bar)
operation. In addition to the total reflux test series, two flood runs at constant liquid rate with L/V>1
were obtained. Also shown in this figure are the measured flooding capacities of the F.R.I. type 2 valve
tray and F.R.I. system limit model prediction.
Figure 4 shows that the flooding capacity factor Cs of the
MVGT tray at total reflux, in terms of superficial area, with the iC4/nC4 system at 100 psia (6.9 bar) is
about 24 percent higher than that of the type 2 valve tray. At a constant liquid weir load of 14 gpm/in
(125 m
3
/h-m), the MVGT tray has 50 percent higher flood capacity than the type 2 valve tray on Cs basis.
Figure 5 is the similar operational diagram but based on tray bubbling area. Compared to the F.R.I. type
2 valve tray, the flood capacity factor of the MVGT tray at total reflux, based on the bubbling area, is
about 32 percent higher than that of the type 2 tray.
iC4/nC4 165 psia (11.4 bar) -- Similar test results were found for the iC4/nC4 165 psia (11.4 bar)
operation as shown in
Figures 6 and 7. Figure 6 shows the results presented in terms of superficial
capacity factor, Cs.
Figure 7 is based on bubbling area. At total reflux, the MVGT tray shows a 28
percent higher capacity, on superficial area basis, than the type 2 valve tray. And the capacity is 32
percent higher than the type 2 tray based on the bubbling area as indicated in
Figure 7. At a constant
liquid weir load of 14 gpm/in (125 m
3
/h-m), the MVGT tray has 70 percent higher capacity than the type
2 valve tray based on the superficial area. Also included in these two figures are the results of the sieve
tray tested in 1987 with the same system and column pressure. It can be seen from the figures that the
MVGT tray also has a higher capacity than the 1987 sieve tray.
Efficiency
iC4/nC4 100 psia (6.9 bar) -- Figures 8 and 9 show the efficiencies of the MVGT tray for the iC4/nC4
system at 100 psia (6.9 bar), where efficiency was calculated based on the slope from liquid samples from
trays 1 to 7.
Figure 8 is the efficiency curve in terms of superficial capacity factor, Cs. And Figure 9 is
based on the capacity factor based on the bubbling area, Cb. Also shown in those two figures are the
efficiency results of the F.R.I. type 2 valve tray. As indicated in the figures, the MVGT tray separation
efficiency is about 3 to 4 percent higher than that of the type 2 valve tray at low to medium vapor rates,
but substantially higher at high vapor rates because the MVGT tray has a higher capacity.
Figure 10
shows the sectional effect on efficiency. The top section efficiencies were calculated using the slope of
the composition profile for trays 5-7, while the bottom section efficiency was obtained from the slope of
the trays 1-4 profile. As shown in the figure, there is no significant difference in the sectional efficiency
except at extremes of loads which was confirmed by the composition profiles presented in
Figure 11.
iC4/nC4 165 psia (11.4 bar) Efficiency results for the iC4/nC4 system at 165 psia (11.4 bar) are shown
in
Figures 12 and 13. Also shown in these figures are the test results of the F.R.I. type 2 valve tray and
the sieve tray tested in 1987.
Figure 12 gives the results presented in terms of superficial capacity factor,
and
Figure 13 shows results based on the bubbling area. Similar to the 100 psia (6.9 bar) results, the
MVGT tray shows about a 3 to 4 percent higher separation efficiency than the type 2 valve tray at low to
medium vapor rates. The 1987 sieve tray efficiency is about 5 to 6 percent higher than the MVGT tray
efficiency at low to medium vapor rates. However, the MVGT tray efficiency is substantially higher than
both the type 2 valve tray and the 1987 sieve tray at high vapor rates due to its higher capacity.
Figure 14
shows the top section and the bottom section tray efficiencies of the MVGT tray. The top section
efficiencies were calculated using the slope of the composition profile for trays 5-7, while the bottom
section efficiency was obtained from the slope of the trays 1-4 profile. Similar to 100 psia (6.9 bar )
