Computing Assingment Problem 3,4 and 5

8/13/2019 Computing Assingment Problem 3,4 and 5

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Title: Computing Assignment using ProII

Name: Ahmad Tarmizi Abd Wahab

Registration Number: 110231839

Date: 27th

April 2013

Problem 3

Flow diagram for this problem is shown below:

The phase envelope plot for both Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) methods are

shown below:

a) Soave-Redlich-Kwong (SRK)

PH1

S1

1.0

1.0

100.030

F

PSIA

LB-MOL/HR

Temperature, F

-270.0 -210.0 -150.0 -90. 0 -30. 0 30.0

Pressure,psia

0

300.0

600.0

900.0

1200.0

1500.0

PHASE ENVELOPE PH1

S1

CriticalP oint

S1- L/F=0.050000

S1- L/F=0.010000


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b) Peng-Robinson (PR)

The cricondentherm, cricondenbar and critical points for the three streams for both methods are asfollows:

a) Soave-Redlich-KwongStream Conditions Temperature (F) Pressure (PSIA)

1

Cricondentherm 30.11 614.00

Cricondenbar -24.18 1319.66

Critical point -88.44 893.86

1

(5% liquid fractions)

Cricondentherm -68.99 913.59



1





Temperature, F

-2 70. 0 -2 1 0. 0 -1 5 0. 0 -90 .0 -30 .0 3 0. 0

Pressure,psia

0

300.0

600.0

900.0

1200.0

1500.0

PHASE ENVELOPE PH1

S1

CriticalPoint

S1-L/F=0.050000

S1-L/F=0.010000


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b) Peng-RobinsonStream Conditions Temperature (F) Pressure (PSIA)

1

Cricondentherm 26.12 581.40



1





1





Based on Met Office: UK climate: Winter 2011/12, the UK mean temperature for the winter was

3.3C1 which is equivalent to 38F. Cricondentherm is the maximum temperature by which the

condensation takes place. Therefore, by referring to the cricondentherm temperatures for all stream

conditions for both methods, the mean temperature of 38F does not fall below any of those values.

Hence, condensation will not happen.

The worst case scenario that could happened is where the temperature during the winter falls below

the cricondentherm and the liquids condensed, which one way to prevent such phenomenon from

happening is to apply insulator along the pipe. By using this method, it will prevent the contact from

the surrounding temperature with the pipe.

Cricondenbar does not take into account since, the liquid stream is already in gas state, which is

natural gas, therefore, a phase change of gas to gas is will not happen.

In comparison, the Peng-Robinson method gives a lower value for cricondentherm, cricondenbar

and also critical point for both temperature and pressure.

1http://www.metoffice.gov.uk/climate/uk/summaries/2013/winter.Last accessed 27

thApril 2013
http://www.metoffice.gov.uk/climate/uk/summaries/2013/winterhttp://www.metoffice.gov.uk/climate/uk/summaries/2013/winterhttp://www.metoffice.gov.uk/climate/uk/summaries/2013/winterhttp://www.metoffice.gov.uk/climate/uk/summaries/2013/winter


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Problem 4

The flow diagram for this problem is shown below:

Condenser and reboiler duties required to maintain the specified methanol purity and recovery are -

0.0189 MKcal/hr and 0.0190 MKcal/hr respectively.

The column diameter required to meet specifications is

The specifications are met since the calculated values are the same as in the specified values.

2

3

4

5

6

7

8

9

10

11

12

13

14

1

15T1

S1

78.1

760.0

1435.000

C

MM HG

KG-MOL/HR

S3

78.1

760.0

1433.959

C

MM HG

KG-MOL/HR

S2

65.1

760.0

1.041

C

MM HG

KG-MOL/HR


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The design diameters of the trays are shown as follows:

Tray Design Diameter (mm)

2

3

4

5

6

7

8

9

10

11

12

13

14

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Computing Assingment Problem 3,4 and 5