FAKULTI KEJURUTERAAN KIMIA

PROCESS SIMULATION LABORATORY

( CPE 613 )

No. Title Allocated Marks (%) Marks1 Procedure 102 Process Flow Diagram (PFD) 203 Workbook 304 Questions & Discussions 40

Total marks 100

Remarks :

Checked by: Rechecked by:

Date: Date:

NAME : TUNKU FARAH SHAHEERA BT TUNKU SULIEMAN

STUDENT ID : 2013860184

EXPERIMENT : 3 (AN ACYCLIC PROCESS)

DATE PERFORMED : 23RD OCTOBER 2015

SEMESTER : 5

PROGRAMME : EH 2205B

SUBMIT TO : MADAM NORASMAH MOHAMMED MANSHOR

1.0 Procedure

1. Click on the start menu. Select Aspen HYSYS V8.6 software.

2. Open a new case. Click the new in the toolbar.

3. Enter the following values in the specified fluid package view:

Property package Peng – Robinson

Components 1. n-heptane

2. Toluene

3. Hydrogen

4. Add a reaction and choose a conversion type of reaction.5. Add a stream with following values.

Name Stream 1

Temperature 65˚F

Molar flow 100 lbmole/h

Figure 1 : Conditions at Stream 1

6. At the Stream 1, the composition values for the three components was added as given in the stoichiometry equation.

C7H16 → C7H8 + 4H2

Components Mole fractionsn-heptane 1.000Hydrogen 0.000toluene 0.000

Figure 2 : Mole fractions in Stream 1

7. A heater was added so that the temperature of feed stream increased to 800˚F.

Figure 3 : Conditions at a Heater

8. At the outlet of the heater, we labeled as Stream 2 which the conditions of the stream is the temperature of the stream is 800⁰F and the pressure of 101.3 kPa.

Figure 4 : Conditions at Stream 2

9. A conversion reactor was added after the heater with following values.

Name Oxidation Reactor

Temperature 800˚F

Molar flow 100 lbmole/h

Figure 5 : Conditions in a Conversion Reactor.

Figure 6 : Compositions of the components in a conversion reactor

10. A condenser was added with the following conditions temperature of 65⁰F and pressure of 101.3 kPa.

Figure 7 : Conditions in a Condenser

11. The composition of the components in the entering and leaving stream of the condenser was calculated by Aspen HYSYS software.

Figure 8 : Composition of the components in a condenser

12. After the effluent from condenser produced, it was purged into a separator stream to remove hydrogen gas at least up to 96%. The conditions of the separator was the same as in the condenser.

Figure 9 : Conditions at the Separator

13. But the compositions for the overhead and bottom products of the separator was calculated separately by the Aspen HYSYS software

Figure 10 : Compositions of the components in the Separator (Overhead and Bottom)

2.0 Process Flow Diagram (PFD)

Figure 11 : Process Flow Diagram for the Production of Toluene by dehydrogenation of n-heptane.

3.0 Discussion

The objectives of this laboratory project are to install and converge a conversion reactor and to simulate a process involving reaction and separation. In industry, the production of toluene came from many processes and reactions such as Friedel-Crafts reaction, decarboxylation, wurtz-Fittig reaction and reaction using Grignard reagent. But for this project, the process was carried out by hydrogenation of n-heptane over Cr2O3 catalyst adsorbed on Al2O3 to produce toluene.

C7H16 C7H8 + 4H2

In this lab, some hints was introduced while conducting this project which is assuming that no pressure drop in all equipments. Peng Robinson fluid packaged is used to satisfy the thermodynamic parameters and conditions in this unit operation.

According to process flow diagram (PFD), the inlet feed stream which consist of h-heptane was introduced into a heater, E-100 at 65⁰F. The heater functions to increase the temperature of the feed stream up to 800⁰F. After the feed stream temperature has increased, it was fed to the conversion reactor, CRV-100. In this reactor, the Cr2O3 catalyst is taking part in the reaction which as we know the key aspects of the catalyst is it will change itself during the process by interacting with the reactant molecules and increase the rate of reaction of the process. The reactor operates isothermally and converts 15 mol % of n-heptane to toluene. From the PFD, the composition of n-heptane at the outlet of the catalytic reactor is 0.5313 mol. A cooler is needed to cool back the temperature from the effluent stream of the catalytic reactor back to 65⁰F and transfer the effluent into flash separator. The cooler acts to suddenly decline the temperature and increased the liquid phase, so that as it feed into the separator, a part of the liquid will “flashes” into vapor. The flash separator is used to remove the hydrogen at least up to 96%.

At the flash separator, there are two outlet streams produced which call overhead product and bottom product. For the overhead product, the hydrogen-rich vapor was purged out of this stream while the bottom one consists of toluene/n-heptane liquid product. To answer some questions given in this project, the phase of n-heptane at the inlet of the heater is in liquid phase because the vapor fraction of n-heptane at Stream 1 is 0. Meanwhile, at the outlet of the heater is in gas phase due to its vaporization after the temperature is increased by the heater from 65⁰F to 800⁰F. Note that boiling point of n-heptane is 209.6⁰F which is much lower than 800⁰F and the vapor fraction of n-heptane at Stream 2 is 1.

As for the conversion part in the catalytic reactor, the mole fraction for each component after conversion of 15% of n-heptane is given by:

Component Vapor Phase (S3) Liquid Phase (S4)n-heptane 0.5313 0.5294

Toluene 0.0938 0.0935Hydrogen 0.3750 0.3771

The phase and the temperature of the separator feed stream are vapor-liquid mixture and 65⁰F, respectively. At the separator, the mole fraction for each component at the inlet (Stream 6) and outlet (Stream 7) separator is given as:

Component Vapor Phase (S6) Liquid Phase (S7)n-heptane 0.0384 0.8488

Toluene 0.0058 0.1504Hydrogen 0.9558 0.0009

As the flash separator complete the process, the hydrogen gas removed by the separator has achieved approximately to 96% which is 0.955825 mol of hydrogen. Therefore, in order to increase the purity of toluene and removed effluent gas up to 96% and above, we shall install the adjuster in HYSYS simulation to adjust the material stream before and after going the separator. A distillation column also can be install right after the flash separator unit to recover the liquid product.

As a conclusion, the objectives of this project has achieved. All of the unit operations in the process flow diagram has converged in HYSYS simulation and the conversion of the product stream is dependent on the temperature. As the temperature decreased, the conversion of the effluent will increase.