VLE Manual

SOLTEQ® VAPOUR LIQUID EQUILIBRIUM UNIT (Model: BP 16)

1.0 INTRODUCTION

This SOLTEQ® Vapour Liquid Equilibrium Unit (Model: BP 16) has been designed for teaching, training and research purposes on vapour liquid equilibrium. The unit is suitable for investigating the relationship between vapour and liquid at equilibrium for different mixtures. It can be operated at atmospheric pressure as well as elevated pressures of up to 4bar(g). It mainly consists of an evaporator, immersion heater, condenser and product coolers. Instruments are provided for the measurement of the evaporator’s pressure and temperature while provisions are also given for both liquid and vapour sampling.

Among the special features of the unit are:

All components are made of stainless steel to withstand corrosion and most chemicals used during experiments.

Insulation of evaporator to prevent heat loss to the surroundings. Digital instrumentations allow more accurate measurements of pressure and temperature. Level sight tube at evaporator for observation of liquid level. Top and bottom sample collectors to ensure depressurization and cooling of samples

before collection. 2.0 GENERAL DESCRIPTION

The SOLTEQ® Vapour Liquid Equilibrium Unit (Model: BP 16) can be used to study any binary system as well as multi component systems. For example, a liquid mixture of methanol-water with a known composition is initially fed into the evaporator. When the heater is switched on, the mixture will heat up and start to boil. The heater has a temperature controller which will switch off the heater if the evaporator’s temperature exceeded the setpoint value. As the liquid boils, vapour will rise from the evaporator into the condenser. The vapour starts to condense, and the liquid will flow back into the evaporator. The process continues until an equilibrium state is reached between the vapour and liquid phases. This is when the temperature remains constant. Samples of vapour and liquid can then be taken to determine their compositions.


2.1 Unit Assembly

Figure 1: Unit Construction for Vapour Liquid Equilibrium Unit (Model:BP16)

1. Condenser 6. Pressure Relief Valve

2. Evaporator 7. Control Panel

3. Bottom Sample Collector 8. Top Sample Collector

4. Cooling Water Supply 9. Rotameter

5. Cooling Water Drain 10. Heater

1

2

3

1 5

4

6

7

8

9

10


Figure 2: Process flow diagram for the Vapor-Liquid Equilibrium Unit


2.2 Experiment Capabilities The unit is capable of performing the following experiments:

Determine the vapour liquid relationship at equilibrium for binary and multi-component systems at atmospheric and elevated pressures.

Study the effect of initial mixture composition upon the boiling temperature and vapour liquid phase compositions.

Determine the minimum boiling point of a binary mixture. 2.3 Technical Specifications

Operating limits: Temperature: 0 to 200°C Pressure: 0 to 10 bar(g) Max. cooling water pressure: 2 bar(g)

2.4 Overall Dimensions Height: 2.00 m Width: 1.27 m Depth: 0.63 m

2.5 Instrumentation and Control

Tag Description Range

TIC-01 Evaporator temperature controller, Liquid temperature sensor

0–200.0°C

TI-02 Vapour temperature sensor 0–200.0°C

PI-01 Evaporator pressure sensor 0–10 bar(g)

PI-02 Condenser pressure gauge 0–10 bar(g)

FI-01 Cooling water flow rotameter 0–10 L/min

– Pressure relief valve at condenser 0–10 bar(g)

3.0 SUMMARY OF THEORY 3.1 Introduction of Vapor-Liquid Equilibrium Let us consider the meaning of an equilibrium state as applied to a multi component,

multiphase system comprised of non-reacting substances. As an example, suppose we introduce liquid water and liquid methanol into a vessel equipped with means of measuring pressure and temperature and of withdrawing samples of liquid and vapour for analysis. We now place the vessel in a bath maintained at a specific temperature. Within the vessel water and methanol will begin to distribute themselves between liquid and vapour phases. This distribution process involves vaporization and diffusion. Eventually, the system will be in an equilibrium state, which can be verified when successive reading of the temperature, pressure, liquid mol fractions and vapor mol fractions are identical. This equilibrium state is reproducible and according to the phase rule,the condition is unique for a two-component, two-phase system when any two of its intensive properties are specified, although the quantities of the phases, and thus the extensive properties, may differ. In applying thermodynamics to phase equilibrium, we are mainly interested in intensive properties and the relationships between them; therefore the phase rule specifies the condition necessary to determine the equilibrium state.


As we have already seen, the successful application of the methods of thermodynamics

requires an empirical understanding of the system under study. To assist in cultivating this understanding, we first consider various ways in which vapor-liquid equilibrium data may be presented and thereby seek to develop a physical appreciation of the variables of phase equilibrium and how they are interrelated. Often, however, the concept of phase equilibrium and the variables expressing it do not acquire physical meaning until one considers the experiment determination.

3.2 Pxy and Txy Diagram

In studying vapor-liquid equilibrium in a binary system, there are four intensive variables which will concern us; temperature, pressure, a single liquid mole fraction, and a single vapor mole fraction. Only a single mol fraction is required to describe the composition of a phase in a binary system because of the condition that mol fractions in a phase must sum to unity. Application of the phase rule to a binary system shows that the maximum numbers of intensive variables, which can be specified, are two - this occurs when only a simple phase is present. Therefore, to graphically represent the phase behavior of a binary system, a three-dimensional plot is necessary such as shown in Figure 3. It shows that each phase is represented by a surface on PTxy coordinates. The upper surface represents liquid phase, and the lower surface represents the vapor phase. Where there is equilibrium between the two phases, we know that the temperatures and pressure must be equal. Therefore, the compositions of the equilibrium phases are determined by the intersection of a constant-temperature plane with a constant-pressure plane.

Figure 3: Ptxy diagram

In Figure 3 a constant-temperature plane is shown by the lens-shaped envelope AB which lies in the vertical plane DAVaLaBE. This envelope is shown to intersect a constant-pressure envelope KVaLaH that lies in the horizontal plane. The intersection of the envelopes occurs in two places: on the liquid surface at the point La and on the vapor surface at point Va. These points represent values of x1 and y1 that are in equilibrium at the temperature and pressure we have selected. Equilibrium liquid and vapor compositions are shown as Lb and Vb where the isothermal plane 0CIVVbLbNP corresponding to Tb intersects the isobaric pane MLVbLbC1 corresponding to Pb.


Because three variables are required to describe the state of a single phase, the representation of phase behavior on a two-dimensional plot can be accomplished by holding one variable constant; three such plots are possible. These types of plots corresponding to the three-dimensional diagram in Figure 3 are shown on Figure 4, 5 and 6 unless we are concerned with the equilibrium near the critical region, we will have little use for the PT plot and we will find that the envelopes on Txy and Txy diagrams will span the entire range of fractions. Usually we are interested in systems at low to moderate pressure where the constant-temperature envelope will resemble Ta in Figure 5 and the constant-pressure envelope will resemble Pa in Figure 4.

Figure 4: Pxy diagram

Figure 5: Txy diagram


Consider equilibrium at a constant temperature of Ta as requested on Figure 4. At equilibrium the pressure must be equal for each phase and a horizontal line ties together the saturated liquid and vapor curves. Such lines determine the equilibrium and vapor compositions at a given pressure and are called tie lines. The phase rule requires specification of two variables to determine the two-component, two-phase system. As we have already specified Ta, only one other variable may be chosen. If we choose either x1 or y1, we have fixed a point on either saturated curve and tie line determines P and mole fraction of the other phase. In Figure 5, a constant-pressure diagram; tie lines are characterized by temperature. 3.3 Ideal System In a homogeneous solution the number of molecules of any one component per unit area of surface will be less than if that component exposed the same area of surface in the pure liquid state. For this reason the rate of vaporization of a substance per unit area will decrease with dilution. According to Raoult’s law the resulting partial pressure of component A in the vapour phase is

AAA Pxp (1)

where xA = the mole fraction of component A in the boiling liquid, and PA = saturation pressure of pure component A at the temperature of the liquid mixture. Dalton’s law states that the total pressure of an ideal gas mixture equals the sum of the partial pressures

i

ipP (2)

The partial pressure pi is by definition equal to the product of the gas-phase mole fraction and the total pressure

Pyp ii (3)

Equations (1) and (3) give the mole fraction of component A in the gas phase as

P

Pxy AA

A (4)

Extend to a binary system, Raoult’s law and Dalton’s law (equations (1) and (2)) give

BBAABAAABA PPPxPxPxppP )()1(

or

BA

BA

PP

PPx

(5)

Equation (5) is used to find xA for ideal binary mixtures at selected temperatures between the boiling temperatures of the two pure components at pressure P, and equation (4) gives the corresponding value of yA. The distribution coefficient, also called the vaporization equilibrium constant or just the K-value for the component i, is defined by the equation

iiA xKy (6)

The relative volatility of component A relative to component B is defined as

BB

AA

B

AAB

xy

xy

K

K (7)


or in combination with equation (5) for ideal mixtures,

BAAB PP (8)

Raoult’s and Dalton’s law give reasonable estimates for cognate molecules such as benzene and toluene when distilled at normal or lower pressure. Pairs represent are examples of ideal systems. 3.4 Non-Ideal Homogeneous Mixtures In a close to ideal mixture, such as benzene and toluene, the intermolecular forces between two benzene molecules are approximately the same as between a benzene and a toluene molecule. Deviations from Rauoult’s law are due to changes in the intermolecular forces, of which the hydrogen bond plays an important role. The hydrogen bonds O→HO, N→HO, O→HN are strong. In water the hydrogen bond is especially strong. A high fraction of a component with fewer tendencies to form hydrogen bonds with water, will reduce the hydrogen bonds in the water and increase its volatility. The increase in vapour pressure corresponds to a positive deviation from Raoult’s law as shown in Figure 6 for the ethanol-water mixture at a

temperature of 60 C. The total pressure of this mixture goes through a maximum. A composition giving maximum pressure when boiling at constant temperature, gives a minimum boiling temperature when boiling at constant pressure. At this point the composition of the vapour equals the composition of the liquid, and it is called an azeotropic mixture. Figure 7 shows the mole fraction y of ethanol in the liquid as a function of the mole fraction x of ethanol when an ethanol-water mixture boils at atmospheric pressure. The mole fraction x = y = 0.894 or 96 percent by volume is the azeotropic mixture of ethanol and water. The boiling-point of the

azeotropic mixture is 78.15 C, which is below the boiling-points of the pure components. The mixture is called a minimum azeotrope. At reduced pressures the azeotrope shifts towards higher alcohol concentrations. It disappears at pressures below 0.08 bar absolute.

Figure 6: Vapor Pressure of ethanol ( PA) and water (PB) and total P = ( PA)+ (PB) of ethanol-water mixture. X= mole fraction of ethanol in liquid. Dashed lines correspond to Raoult’s law


A mixture of acetone and chloroform shows a different type of deviation from Raoult’s law. The pure components do not have hydrogen bonds. But chloroform has an active hydrogen atom that acts as donor of an electron, thus forming a hydrogen bond between an acetone and a chloroform molecule. This gives a negative deviation from Raoult’s law (Figure 8). Figure 9 shows the mole fraction y of acetone in the vapour as a function of the mole fraction x of acetone in the liquid when the mixture boils at atmospheric pressure. This mixture has a maximum azeotrope, i.e. the boiling temperature of the azeotrope is above the boiling-points of the pure components.

Figure 7: Mole Fraction y of ethanol in vapour as a fuction of mole fraction x of ethanol in liquid of ethanol-water mixture boiling at atmospheric pressure. Deviations from ideal behaviour in the liquid phase are taken into account by the liquid phase activity coefficient γ, and equation (4) becomes

P

Pxy A

AAA (9)

Equations (6) and (9) give

P

PK A

AA (10)

The activity coefficient is a function of temperature and composition of the liquid phase. An appropriate models (Van Laar’s, Margules’, Wilson’s, UNIQUAC etc.) have been suggested for calculation of the activity coefficient. Van Laar’s third-order equations for binary mixtures of non-electrolytes are

2221121

2

2121

)(ln

xAAx

xA

(11)


Figure 8: Vapour pressure of acetone ( PA) and chloroform ( PB) and total pressure P = ( PA)+ (PB) of acetone-chloroform mixture. X= mole fraction of acetone in liquid. Dashed lines correspond to Raoult’s law

Figure 9: Mole Fraction y of acetone in vapour as a fuction of mole fraction x of acetone in liquid of acetone-chloroform mixture boiling at atmospheric pressure.


3.5 PT Diagram

Figure 10: PT diagram

Figure 6 shows the curves formed by the intersection of the two constant-composition planes, TSRVaCIII and VVVULaCII, with the liquid and vapor surfaces on Figure 3. Note that it is possible for mixtures to have a critical temperature, CII and CIII, those above those of either pure component. The intersection of the projections of the vapor portion of one curve with the liquid portion of another locates an equilibrium point, La, Va.

As temperature increases there is a narrowing of the range of composition over which a liquid

phase can exist. For example, from Figure 1 it is seen that for the isothermal plane CIVVbLbNP corresponding to Tb component 2 is above critical temperature and therefore cannot exist as a pure liquid – in fact, there is a maximum mol fraction component 2 above which no liquid phase can form at this temperature. The composition range also narrows as the pressure is increased. Figure 3 shows that the lens-shaped envelope formed by the intersection of the constant-pressure plane, MLVbLb

0CI at Pb with the liquid and vapor surfaces does not with the liquid and vapor surfaces does not extend to x1 = y1 = 1. This limited composition range can also be discerned from figure 5 where it is observed that pressure Pb lies above the vapor pressure curve for component 1. As the temperature or pressure continues to increase, the composition range steadily diminishes. Often, a point is reached where neither component can exist as pure conjugate liquid and vapor phases.

The preponderance of experimentally determined vapor-liquid equilibrium data is reported at

either constant temperature or pressure as either of these constraints can be easily imposed on an experimental determination. Unless we are dealing with systems following ideal solution behavior where the phase behavior may be calculated from pure component properties, experimental data are needed to construct the phase diagrams.


4.0 GENERAL OPERATING PROCEDURES

4.1 General Operation It is important that the user read and fully understand all the instructions and precautions stated in the manufacturer's manuals supplied with the equipment prior to operation. The following procedures will serve as a quick reference for operating the equipment.

4.2. Evaporator temperature control

The evaporator temperature limit can be controlled by adjusting the setpoint of TIC-01 on the control panel. The top value indicates the current bottom liquid temperature, while the smaller bottom value indicates the setpoint temperature. Simply use the arrow keys to adjust the temperature setpoint to the desired value, usually slightly above the expected boiling point of the liquid mixture as follows :

Press lighty UP or DOWN arrow key to increase or decrease the value by one. Press and hold UP or DOWN arrow key to increase or decrease the displayed value at

a rapid rate. New data will self-enter in five seconds, or can be entered by pressing the adanced key.

4.3 Heater protection

The heater must be fully immersed in liquid when turned on to prevent heater burn-out. Always fill the evaporator with at least 3-L of liquid before running any experiments. The liquid level at the sight tube should be above the safety line before the heater can be switched on.

4.4 Cooling water control

Use valve V10 which installed below the flowmeter FI-01 to adjust the cooling water flow rate into the condenser. When running the unit, the exit cooling water temperature from the condenser shall not exceed 40 °C. During shut-down, open valve V11 to quickly cool down the liquid in the evaporator. Valve V12 is used to cool the liquid sample in the bottom sample collector.

4.5 Pressure relief valve

The operating pressure limit is preset at the maximum of 10 bar(g). To reduce this limit, pressurize the unit to the desired pressure using compressed air. Unscrew the cap on the pressure relief valve and turn the nut counter-clockwise to reduce the pressure limit until the valve starts to open. Screw the cap back onto the valve.

4.6 Venting and drainage

As a safety precaution, always cool down and depressurize the unit first before opening any valves for draining. Follow the general shut-down procedures as described in Section 6.3.


5.0 EXPERIMENT PROCEDURES

5.1 General Start-up Procedures 1. Obtain the equilibrium data for the binary system to be studied from literature.

2. Prepare a calibration curve of refractive index vs. composition plot for the particular binary system. Refer to Appendix A.

3. Check that the evaporator and condenser is empty of liquid.

4. Ensure all valves are initially closed and the heater power switch is turned off.

5. Switch on the main power at the control panel. Check all sensors and indicators are functioning properly.

5.2 General Experiment Procedures 1. Prepare about 3 to 6-L of liquid mixture at the desired composition and pour it into

the evaporator through valve V1. Close valve V1.

2. Open valves V13 and V14 at the level sight tube. Make sure that the liquid level is above the safety line on the level sight tube. Close back valves V13 and V14.

3. For operation at atmospheric pressure, open valve V8.

4. For operation at elevated pressures, turn on the compressed air supply and set the desired pressure at the regulator. Open valve V9 to start pressurizing the unit, then close valve V9 when the pressure is reached.

5. Open and adjust valve V10 to allow about 5 to 10 L/min of cooling water to flow through the condenser.

6. Set the temperature controller TIC-01 to slightly above the expected boiling point of the liquid mixture.

7. Switch on the heater.

8. Observe the temperature rise in TIC-01. When the temperature at TI-02 starts to increase sharply, the liquid in the evaporator has begun to boil. Observe the pressure at PI-01. Wait for all temperatures and pressure to stabilize at a steady state value.

9. Record the evaporator pressure and the liquid and vapour temperatures.

10. Collect a vapour and liquid sample from the unit as described in Section 5.4.


5.3 General Shut-down Procedures

1. Switch off the heater.

2. Open valve V10 to increase the cooling water flow rate through the condenser.

3. Open valve V11 to allow cooling water to flow through the cooling coil in the evaporator.

4. If the unit is pressurized, slowly open valve V8 to depressurize the unit.

5. Wait for the temperature at the unit to drop to below 50°C.

6. Open valves V2 and V3 to drain all liquid from the evaporator.

7. Open valves V5 and V7 to drain all liquid accumulated at the condenser.

8. Close all valves and switch off the main power at the control panel.

5.4 Sampling Procedures Both vapour and liquid samples can be taken from the unit for analysis. Note: Sample volume to be taken should be as minimum (e.g less than 25ml) as possible to avoid any effect on the volume remained in the evaporator. 1. Vapour sampling from the condenser

i) Ensure that vent valve V6 is opened and drain valve V7 is closed. ii) Slowly open valve V5 to allow some condensed vapour from the condenser to

flow into the top sample collector. Close valve V5. iii) Open valve V7 to collect the sample in a sampling vial. iv) Immediately close the cap on the vial and immerse it in cold water.

2. Liquid sampling from the evaporator

i) Ensure that vent valve V4 is opened and drain valve V3 is closed. ii) Open valve V12 to allow cooling water to flow through the bottom sample

collector. iii) Then, slowly open valve V2 to allow some liquid from the evaporator to flow

into the sample collector. Close valve V2. iv) Open valve V3 to collect the sample in a sampling vial. v) Immediately close the cap on the vial and immerse it in cold water.


5.5 EXPERIMENT 1: Equilibrium Curve at Atmospheric Pressure

Objective:

To construct an equilibrium curve for the methanol-water system at atmospheric pressure.

Procedures:

1. Perform the general start-up procedures as described in Section 5.1.

2. Prepare about 12-L of pure methanol and 5-L of deionized water.

3. Open valve V8.

4. Pour 0.1-L methanol and 3-L water into the evaporator through valve V1. Close valve V1.

5. Open valves V13 and V14 at the level sight tube. Make sure that the liquid level is above the safety line on the level sight tube. Close back valves V13 and V14.

6. Open and adjust valve V10 to allow about 5 L/min of cooling water to flow through the condenser.

7. Set the temperature controller TIC-01 to about 100°C. Switch on the heater.

8. Observe the temperature rise in TIC-01. When the temperature at TI-02 starts to increase sharply, the liquid in the evaporator has begun to boil. Observe the pressure at PI-01. Wait for all temperatures and pressure to stabilize at a steady state value.

9. Record the evaporator pressure and the liquid and vapour temperatures.

10. Collect a liquid and vapour sample from the unit as described in Section 5.4. Analyze the samples to determine their compositions.

11. Switch off the heater and open valve V11 to allow cooling water to flow through the cooling coil in the evaporator.

12. Wait for the temperature at TI-02 to drop significantly to signify that boiling has stopped. Close valve V11.

13. Collect all the liquid from the condenser by opening valve V5 and V7 and pour it back into the evaporator through valve V1. Close valves V5 and V7.

14. Collect all the liquid from bottom sample collector by opening valve V3 while closing valve V2 and pour it back into the evaporator through valve V1. Close valves V3 and V1.

15. Pour an additional 0.2-L methanol into the evaporator through valve V1. Close valve V1. There is now about 0.3-L methanol and 3-L water in the evaporator. Repeat steps 5 to 14 above.


16. Pour an additional 0.2-L methanol into the evaporator through valve V1. Close valve V1. There is now about 0.5-L methanol and 3-L water in the evaporator. Repeat steps 5 to 14 above.

17. Pour an additional 0.5-L methanol into the evaporator through valve V1. Close valve V1. There is now about 1-L methanol and 3-L water in the evaporator. Repeat steps 5 to 14 above.

18. Pour an additional 1-L methanol into the evaporator through valve V1. Close valve V1. There is now about 2-L methanol and 3-L water in the evaporator. Repeat steps 5 to 14 above.

19. Pour an additional 1-L methanol into the evaporator through valve V1. Close valve V1. There is now about 3-L methanol and 3-L water in the evaporator. Repeat steps 5 to 14 above.

20. Open valves V2 and V3 to drain all liquid from the evaporator.

21. Pour 2-L methanol and 1-L water into the evaporator through valve V1. Close valve V1. Repeat steps 5 to 14 above.

22. Pour an additional 1-L of methanol into the evaporator through valve V1. Close valve V1. There is now about 3-L methanol and 1-L water in the evaporator. Repeat steps 5 to 14 above.

23. Pour an additional 2-L of methanol into the evaporator through valve V1. Close valve V1. There is now about 5-L methanol and 1-L water in the evaporator. Repeat steps 5 to 14 above.

24. Perform the general shut-down procedures as described in Section 5.3.

Analysis & Discussions:

1. Record all experiment data in the sample table in Appendix B.

2. Plot the vapour and liquid compositions against the vapour temperature.

3. Construct the equilibrium curve by plotting the vapour composition against the liquid composition.

4. Compare between the composition plot and equilibrium curve obtained from the experiment to the literature data.

6.0 EQUIPMENT MAINTENANCE

1. After each experiment, drain off any liquids from the evaporator and condenser.

2. Make sure that the evaporator, condenser and tubings are cleaned properly. Flush the system with de-ionized water.

3. Wipe off any spillage from the unit immediately.


7.0 SAFETY PRECAUTIONS

1. The unit must be operated under the supervision of an authorized staff who has been properly trained to handle the unit.

2. All operating instructions supplied with the unit must be carefully read and understood before attempting to operate the unit.

3. Always make sure that there is enough liquid all the time to fully submerge the heater and temperature sensor.

4. Be extremely careful when handling liquid at high temperature.

5. Always switch off the heater and allow the liquid to cool down before draining.

6. Do not touch the hot components of the unit.

7. Feed stock which severely affect stainless steel 304 and polypropylene (PP) are not to be used.

8. The system should not be subjected to shock, sudden impact, vibration, or additional load.

9. Restore the system to operating conditions after any repair job.

10. Always check and rectify any leak.

11. Do not exceed the maximum cooling water pressure of 2 bar(g) for the condenser.

12. Be extremely careful when handling hazardous, flammable or polluting materials.

13. Do not stretch the Viton O-rings during servicing.

14. Make sure the system is sufficiently ventilated at all times during operation, maintenance and storage.

15. Only properly trained staff shall be allowed to carry out any servicing or repair job. Manufacturer's manual must always be observed.

8.0 REFERENCES

Yunus A. Cengal & Michael A. Boles, “Thermodynamics – An Engineering Approach”, 3rd Edition, 4th Edition, McGraw Hill, 2002.


APPENDIX A Experimental Data Sheets

PREPARATION OF REFRACTIVE INDEX VS COMPOSITION PLOT 1. Prepare a set of mixtures containing the components of a binary system (A & B) within a specified

range of composition. Calculate the mol fraction and wt% of the more volatile component (A). Refer to the sample table below.

2. For each mixture, obtain their refractive index, RI readings using a refractometer.

3. Prepare a plot of RI vs. composition for the whole range of mixtures. This will serve as the calibration curve for further experiments.

Table 1 : Calibration table for methanol-water

Volume of A (mL)

Volume of B (mL)

Mol fraction wt% Refractive index

(RI)

0 10

1 9

2 8

3 7

4 6

5 5

6 4

7 3

8 2

9 1

10 0

Table 2 : Methanol and water properties.

(A)

Methanol

(99.7%)

(B)

Water

ml

g, 0.79 1

mol

gM , 32.04 18


APPENDIX B SAMPLE TABLE FOR EXPERIMENTS USING THE METHANOL-WATER SYSTEM

Pressure Vol

methanol Vol

water

Temperature (Deg C)

RI Composition experiment

Composition literature

% Error

Liquid Vapour Liquid Vapour Liquid Vapour Liquid Vapour Liquid Vapour

1 atm

0.1 3

0.3 3

0.5 3

1 3

2 3

3 3

2 1

3 1

5 1

APPENDIX C Literature T- xy & x-y Equilibrium Diagrams

Figure 1: T-xy Diagram for Methanol-Water system at 1 atm

T-xy Diagram for Methanol-Water System at 1 atm

60

65

70

75

80

85

90

95

100

105

0.0000 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 1.0000

Liquid / vapor mol fraction

Te

mp

era

ture

('C

)

Figure 2: X-Y Diagram for Methanol-Water system at 1 atm

X-Y Equilibrium Diagram for Methanol-Water System at 1 atm

0.0000

0.1000

0.2000

0.3000

0.4000

0.5000

0.6000

0.7000

0.8000

0.9000

1.0000

0.0000 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 1.0000

Liquid mol fraction

Va

po

r m

ol fr

ac

tio

n

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