Reflux ratio internal

Calculate reflux ratios. The minimum internal reflux ratio is a line from the intercept of the q line with the equiUbtium curve to the yP point on... 

The slope L/V of the operating line is termea the internal-reflux ratio. This ratio in the operating-line equation for the top section of the column [see Eq. (13-21)] is related to the external-reflux ratio R = L + i/D by... 

Tray requirements depend on internal-reflux ratios and ASTM 5-95 gaps or overlaps, and may be estimated by the correlation of Paclde (op. cit.) for crude units and the correlation of Houghland, Lemieux, and Schreiner (op. cit.) for main fractionators. 

The internal reflux ratio is L/V, and is the slope of the operating line. The external reflux is [133] ... 

UK. = Light key component in volatile mixture L/V = Internal reflux ratio L/D = Actual external reflux ratio (L/D) ,in = Minimum external reflux ratio M = Molecular weight of compound Mg = Total mols steam required m = Number of sidestreams above feed, n N = Number of theoretical trays in distillation tower (not including reboiler) at operating finite reflux. For partial condenser system N includes condenser or number theoretical trays or transfer units for a packed tower (VOC calculations) Nb = Number of trays from tray, m, to bottom tray, but not including still or reboiler Nrain = Minimum number of theoretical trays in distillation tower (not including reboiler) at total or infinite reflux. For partial condenser system,... 

Liquid mass velocity, Ib/hr-ft" based on superficial cross section of column Internal reflux ratio, dimensionless Weir length, in. 

The proof strength at which the volatility curve of a particular component intersects that of ethyl alcohol indicates that proof at which the minor constituent will be concentrated in a fractionating column at the limiting condition of total reflux. For practical conditions, the maximum concentration of a particular congener or minor component occurs at a proof in the column at which its volatility is approximately equal to the internal reflux ratio (L/V where L is the molal liquid or overflow rate and V the molal vapor rate). This can be established by the technique... 

Note Reflux ratio R is defined as external Reflux ratio while the model uses internal reflux ratio... 

It is assumed that the nominal QR and the internal reflux ratio r = UV are available for manipulation, and that all column temperatures and the liquid holdups in the reboiler and accumulator, are available as measurements. 

However, most of the batch distillation models (e.g. Mujtaba and co-workers Sorensen and Skogestad, 1996) relate the amount of distillate collected (Hamodei) with the vapour boil-up rate in the column (Vtomm), the internal reflux ratio (Rmodei) and the total operating time (tdig) by,... 

Interestingly, the relationship between the external (R) and internal reflux ratio (r) in a distillation column with continuous flow of reflux and distillate is very similar to Equation (12.7) which is ... 

The solution is started by using Eq. (13-25) to convert the external reflux ratio of 4.5 to an internal reflux ratio of L/V = 0.818. The distillate composition Xp = 0.95 is then located on the diagonal, and the upper operating line is drawn as shown in Fig. 13-26. 

The existence of a methane peak is not considered a phenomenon that will always occur with intermediately permeable gases in multicomponent mixtures. Rather, the peak is thought to be the result of a combination of factors. These factors include composition of the feed mixture, pure-gas permeabilities, and the internal reflux ratio. For instance. Figure 3 indicates that the intermediate-gas composition profile will steadily decrease in a stripper 1.0 m long, but otherwise identical to the column used in this study, fed with a 63.6% N2 - 32.3% CH - 4.1% CO2 mixture under similar total reflux conditions. The presence of an intermediate peak, however, is reminiscent of multicomponent distillation profiles and raises the possibility of withdrawing a side stream enriched with an intermediate gas. 

Typically, the quantity of distillate product that is being condensed and returned to the top of the column needs to be specified. It can be defined as either an internal or external quantity depending upon which variables are used. The internal reflux ratio is defined in terms of flowrates within the rectifying section of the colunm ... 

Steam stripping is to be used to remove a solvent from contaminated soil. An enriching colunm will be used to recover the solvent from the stream. A vapor feed of 40 mol/hr with a composition of 20 mol% solvent and 80 mol% water enters an enriching column. The distillate stream is to have a flow rate of 5 mol/hr and a concentration of 90 mol% solvent. The internal reflux ratio is 0.875 and constant molar overflow (CMO) may be assumed. Graph the operating line to predict the number of equilibrium stages in this enriching column. 

Assuming CMO means that L and V are constant, and the operating line will be straight. The internal reflux ratio is L/V, so the easiest way to plot the mass balance for the column (operating line) is to use the Equation (4.10) ... 

The slope of the operating line is the internal reflux ratio, 0.875. Now that we know the slope, we need only one point to plot the line. It is possible to plot the y-intercept of this line, but an easier point to find is the one where the operating line crosses the diagonal, at xd = 0.9 (liquid and vapor compositions are equal since a total condenser is used, i.e., all vapor is condensed to liquid). 

Find A using mass balances and the internal reflux ratio. 

The internal reflux ratios L/ V for each stage of the column can be expressed in terms of the line segments and coordinates of Fig. 10.6. The ratio of liquid to vapor between stages n - 1 and n-2, for instance, is... 

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