SUMMARY

In this experiment, toluene was produced from n-heptane by dehydrogenation. The objective of this experiment is to install and converged a conversion reactor. Another aim for this experiment is to simulate a process involving reaction and separation. The inlet stream was n-heptane which undergoes varies of process to produce toluene. It has to go through a reboiler, a conversion reactor, a condenser and a separator. A reboiler was set to increase a feed stream temperature to 800 ˚F. Temperature outlet at condenser was varies in order to achieved 96% of conversion at the end of the process.

INTRODUCTION

PROCESS:

Toluene is produced from n-heptane by dehydrogenation over a Cr2O3 catalyst adsorbed on Al2O3.

C7H16 → C7H8 + 4H2

n-heptane is heated from 65˚F to 800˚F in a superheater at molar flow rate 100 lbmole/h and then fed to a catalytic reactor, which operates isothermally and converts 15 mol% of the heptane to toluene. The effluent is fed to a flash vessel to remove hydrogen from the reactor effluent at least up to 96%. Assume that all of the units operate at atmospheric pressure.

OBJECTIVE

1. To install and converge a conversion reactor.2. To simulate a process involving reaction and separation

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THEORY

Toluene is a common solvent, able to dissolve paints, paint thinners, silicone sealants, many chemical reactants, rubber, printing ink, adhesives (glues), lacquers, leather tanners, and disinfectants. It can also be used as a fullerene indicator, and is a raw material for toluene diisocyanate (used in the manufacture of polyurethane foam) and TNT. In addition, it is used as a solvent to create a solution of carbon nanotubes. It is also used as a cement for fine polystyrene kits (by dissolving and then fusing surfaces) as it can be applied very precisely by brush and contains none of the bulk of an adhesive.

Industrial uses of toluene include dealkylation to benzene, and the disproportionation to a mixture of benzene and xylene in the BTX process. When oxidized it yields benzaldehyde and benzoic acid, two important intermediates in chemistry. It is also used as a carbon source for making Multi-Wall Carbon Nanotubes. Toluene can be used to break open red blood cells in order to extract hemoglobin in biochemistry experiments.

When a system in a given initial state goes through a number of different changes in state (going through various processes) and finally returns to its initial values, the system has undergone acyclic process or cycle. Therefore, at the conclusion of a cycle, all the properties have the same value they had at the beginning. Steam (water) that circulates through a closed cooling loop under goes a cycle.

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PROCEDURE

1. Click on the start menu. Select programs.

2. Open a new case. Click the new icon on 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 1

Temperature 65˚F

Molar flow 100 lbmole/h

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

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

Name Oxidation Reactor

Temperature 800˚F

Molar flow 100 lbmole/h

8. A condenser was added after the Ox_vap stream.9. A separator was added.10. An adjuster was added which connect stream 5 and 6.11. The temperature outlet from the condenser was varies until the conversion of stream 6 is

96%.

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RESULT

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1. State phase of n-heptane at 65˚F.Liquid phase

2. State phase of n-heptane at 800˚F.Vapor phase

3. State the mole fraction for each component after conversion of 15% n-heptane

Ox_Vap Ox_Liq

n-heptane 0.5313 0.5303

Toluene 0.0937 0.0936

hydrogen 0.3750 0.3761

4. State the phase and temperature of the separator feed streamVapor – liquid mixture phaseTemperature : 61.5˚F

5. State the superheater duty and cooler duty for this processHeater duty : 5.867 × 10 6 Btu/hr Cooler duty : 5.939 × 10 6 Btu/hr

DISCUSSION

The values of mole fraction for each component can be determined from HYSYS. The

mole fraction for each component was same through all the process except for the separation

process. After the separation process, there was no component of n-heptane. From this

experiment, we can also determine the conversion values. By varies the temperature inlet of the

separator, the conversion value also will varies. Therefore, to achieved 96% conversion after

separation process, the temperature outlet from condenser will be varies. The temperature outlet

from the condenser is 61.5˚F in order to achieve 96% conversion. Thus, we can conclude that as

the temperature decreased, the conversion value will increase. An adjuster was added so that the

HYSYS will adjust a target variable until it reached a specified value.

CONCLUSION

From this experiment, it can be concluded that the conversion value was depending on the temperature. When the temperature inlet decreased, the conversion value will increase.

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RECOMMENDATION

1. Make sure to set the correct reaction in HYSYS. 2. Make sure to connect the correct stream to the equipment.3. Used the right fluid packing in order to get the desired product.4. Make sure to used consistence unit in the calculation.5. Make sure to insert the right value in each unit operation and on the feed stream.

REFERENCE

1. http://en.wikipedia.org/wiki/Toluene#Production 2. http://www.engineersedge.com/thermodynamics/cyclic_process.htm

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