Bubble-point calculation for

BUBBLE - Bubble Point Calculation for a Batch Distillation Column... 

Table 4.10 Bubble-point calculation for a methanol-water mixture using the Wilson equation. 

Table 4.9 Bubble-point calculation for an ideal methanol-water mixture.

In Sec. 10.5 we treated dew- and bubble-point calculations for multicomponent systems that obey Raoult s law [Eq. (10.16)], an equation valid for low-pressure VLE when an ideal-liquid solution is in equilibrium with an ideal gas. Calculations for the general case are carried out in exactly the same way as for Raoult s law,... 

We can predict azeotropic behavior as follows from infinite-dilution /T-values. Using a flowsheeting system, we perform a bubble-point calculation for each species in the mixture. Assuming a mixture contains the species A, B, C, and D, we wish to compute the infinite-dilution L-values for three of the species in the remaining one. For example, we perform a flash calculation where A is dominant and B, C, and D are in trace amounts, using something like a feed composition of 0.99999, 0.000003333, 0.000003333, 0.000003334. It does not... 

A more accurate estimate of N i can be obtained using a mean relative volatility based on values at the top, middle, and bottom of the column. The top temperature is about 75"C, the boiling point of n-hexane at 1.2 atm, and the relative volatility is 2.53 from the vapor pressures in Fig. 19.1. The bottom temperature is about 115 C, by a bubble-point calculation for the bottoms product, giving a relative volatility of 2.15. From Eq. (19.14),... 

Fig. 6 depicts the type of relationship that might be found between downstream gas flow rate and upstream gas pressure in a typical in-process automated bubble point test. The transition pressure is not clearly defined. Actual bubble points (transition pressures) obtained with this type of equipment differ from theoretical bubble points calculated for the same membrane from direct measurement of pore size, and from laboratory-type bubble point testing. 

In this equation, enthalpy Hv is computed for the vapor composition (y,)o obtained from the bottoms bubble-point calculation for Tg. The equation is then applied iteratively with B, Hb, and Hv known, by assuming a value for Vo and computing L and (x,), from... 

A new set of temperatures 7 is computed stage by stage by computing bubble-point temperatures from the normalized Xy values. Friday and Smith showed that bubble-point calculations for stage temperatures are particularly effective for mixtures having a narrow range of Jf-values because temperatures are not then sensitive to composition. For example, in the limiting case where all components have identical K-va ues, the temperature corresponds to the con-... 

Assume that no benzene is present in the bottoms because it has a much higher vapor pressure than toluene, and a sharp separation between toluene and biphenyl is specified. By material balance, the bottoms contains 0.423 Ibmol/hr of toluene and 4.998 Ibmol/hr of biphenyl. A bubble-point calculation for... 

It is sometimes easy to select the reasonable solution. For example, in the bubble point calculation for the nonideal binary mixture isobutanol-water by Henley and Rosen (1969), which is test 67 used by Shacham et al. (2002), there are several... 

Consider the distillation column shown in Figure S-7. where all the non-keys are HNKs. Note that the column is now numbered from the bottom up, since that is the direction in which we will step off stages. With no LNK, a good first guess of concentrations can be made at the bottom of the column, and we can start the stage-by-stage calculations by calculating the reboiler tenperature and the values of yj R from a bubble-point calculation. For the bubblepoint calculation, we want to find the tenperature that satisfies the stoichiometric equation. 

We can estimate the temperature from bubble-point calculations fSection 5.41. Often it is sufficient to do a bubble-point calculation for the feed and then use this tenperature on every stage. A better first guess can be obtained by estimating the distillate and bottoms conpositions (usually NKs do not distribute) and doing bubble-point calculations for both. Then assume that tenperature varies linearly from stage to stage. 

Using the new distillate composition, a recalculation of the dew point assuming 67°C gives a calculated value of = 0.2637. This is very close to that of 0.2627 obtained when the trace amount of D in the distillate was assumed as zero. Hence, the dew point is 67°C. Repeating the bubble-point calculation for the bottoms assuming 132°C, a calculated value of Kc = 1.138, which is close to the value at 132°C. Hence, the bubble point remains at 132°C. If either the bubble- or dew-point temperatures had changed, the new values would then be used in a recalculation o(N . 

The single-stage membrane unit becomes equivalent to a so-called flash vaporization. The flash vaporization calculation itself is straightforward, with the vapor and liquid phases assumed at equilibrium, and is presented in a number of references." " The limits correspond to the dew-point and bubble-point calculations for vapor-liquid equilibrium, which are special or limiting cases for the flash vaporization calculation. It is the object, therefore, to adapt the membrane calculation to the techniques for the flash vaporization calculation and thereby take advantage of the relative simplicity of the latter. 

In effect, the preceding is the bubble-point calculation for the feed. Moreover, the values for (y +,), are obtained simultaneously during the process of calculation. 

Bubble-Point Calculation for Benzene-Toluene Mixture... 

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