Stop if this is equal or close to earlier value of T, else use this value as a new guess. Calculate ik, (note: Number of ik is equal to number of component)Ħ. the temperature-compositiondiagram for isobutane and propane at 1000 kPa. The solution is not straightforward as T is unknown.īUBL T calculationSolution is through iteration, D20 Use the DePriester chart to generate the temperature-composition diagram. XiKi 1 (10.13), For Raoult's Law, Pb xiPisat (10.2) Pb xiPisat Pksat xi Pi So lets calculate Tb at z1=0.6 and P=70kPa.This is point b in previous Tx1y1 diagram. Plot Tx1y1 at P=70kPaChoose T between T1sat and T2sat, calculate P1sat and P2sat and use these to calculate x1 by the following eqn. =1 (10.14) If Raoult's Law valid, Pd 1yiPi So lets calculate Pd at z1=0.6 and T=75oC.This is point c in previous Px1y1 diagram. For Raoult's Law, P xiPisat (10.2) P x1P1sat x2P2sat x1P1sat (1 x1)P2satP (P1sat P2sat )x1 P2sat note: a linear line (y=mx+c)Ĭalculate P for a set of x1 and then calculate y1using,ġ83.211750.888074.960.8750.748366.720.6750.569258.470.4750.331350.230.275041.98075y1P(kPa)x1Tī sat liquid solution or bubblepointPb is by BUBL PĬ sat vapor mixtureor dewpointPd is by DEW PĭEW P calculationCalculate Pd and x1, given y1 and T Substitute yi Kixi into (A)zi (1V )xi KixiV xi (1V VKi ) xi (1V (Ki 1))xiĪcetonitrile(1)/Nitromethane(2)Antoine Eqn,Ĭalculate P and y1, given a set of x1 and T=75oCThis is BUBL P calculation. Let T=1 mol, so V and L are mole fractionszi Lxi Vyi zi (1V )xi Vyi (A) To calculate the T when the last dew disappear as a result of increase in T at constant P. To calculate the T when the 1st dew (drop of liquid) appear as a result of decrease in T at constant P Read value of K-valueat given T and Pe.g.
KJIHLK givesFigure 10.2 (b)Txy phase diagram at constant Pį (liquid solution)L (bubble point)W (dew point)G (Gas mixture) Top surface issaturated-liquid(P,T,x1 surface)ĪEDBLA givesFigure 10.2 (a)Pxy phase diagram at constant T Under surface issaturated-vapor (P,T,y1 surface) T curve for species 2Ĭ1 and C2 are critical points for species 1 & 2 Carry out bubble and dew point calculations for a given mixture Carry out flash calculation in order to determine the vapor/liquidįraction as well as the mixture composition of each phase at specified conditions using available K-Values etc. Apply Raoults law and Henrys law to solve simple thermodynamic Apply simplified VLE equations to obtain data for P-XY, T-XY and X.
How to read a depriester chart kpa and c how to#
It is expected that students have the ability to: Describe the behaviour of VLE and how to simplify the VLE problem. Read this K-value off the chart (approximately 21.3).SKF 2213 Chemical Engineering Thermodynamics Note where the line crosses the methane axis.Connect the points with a straight line.On the right-hand vertical axis, locate and mark the point containing the temperature 60☏.On the left-hand vertical axis, locate and mark the point containing the pressure 100 psia.Example įor example, to find the K value of methane at 100 psia and 60 ☏. Many DePriester charts have been printed for simple hydrocarbons. "K" values, representing the tendency of a given chemical species to partition itself preferentially between liquid and vapor phases, are plotted in between. These nomograms have two vertical coordinates, one for pressure, and another for temperature. DePriester in an article in Chemical Engineering Progress in 1953. DePriester Charts provide an efficient method to find the vapor-liquid equilibrium ratios for different substances at different conditions of pressure and temperature.
0 kommentar(er)
