ABSTRACT

In this study, the simulation model for the reactor section was developed using ASPEN PLUS 8.6, and the optimization was carried out using MINITAB version 18, using the response surface methodology (RSM). The purpose of this work is to maximize yield of urea from the reactor section employing optimum parameters. The results from the initial and optimized parameters of the reactor unit were compared. Initial parameters of temperature (168⁰C) and pressure (143 bars) gives 42.5% conversion of ammonium carbamate to urea, while the optimized parameters of temperature (244⁰C) and pressure (163.5 bars) gives 80.19% percent conversion of ammonium carbamate to urea. This gives as increase of 37.69% conversion of ammonium carbamate to urea. From the results, energy cost of recycling unconverted ammonium carbamate to urea can be minimized. The results gotten from the simulation model and the RSM optimization model were validated.

 TABLE OF CONTENT

CERTIFICATION.. i

ABSTRACT. ii

DEDICATION.. iii

ACKNOWLEDGEMENT. iv

LIST OF FIGURES. v

LIST OF TABLES. vi

CHAPTER ONE. 1

1.1 BACKGROUND TO THE STUDY. 1

1.2 STATEMENT OF THE PROBLEM... 3

1.3 AIM AND OBJECTIVES OF THE STUDY. 3

1.4 SIGNIFICANCE OF THE STUDY. 4

1.5 SCOPE OF THE STUDY. 4

CHAPTER TWO.. 5

2.1 CONCEPT OF UREA.. 5

2.2 USES OF UREA.. 7

2.2.1 CHEMICAL INDUSTRY. 7

2.2.2 AUTOMOBILE SYSTEMS. 7

2.2.4 Medical uses. 8

2.2.5 Miscellaneous uses. 9

2.3 UREA SYNTHESIS PROCESS. 10

2.4 FERTILIZERS. 12

2.4.1 UREA AS EFFICIENT FERTILIZERS. 14

2.5 COMPUTER MODELING TECHNIQUES. 17

2.5.2 THERMODYNAMIC MODELING OF UREA.. 21

2.5.3 THEORETICAL ANALYSIS. 22

2.5.3.1 REACTION PATHWAY. 22

2.5.3.2 PROCESS WINDOW... 23

2.6 EMPIRICAL REVIEW... 25

CHAPTER THREE. 41

3.1 DATA COLLECTION.. 41

3.2 PROCESS DESCRIPTION.. 42

3.3 SIMULATION MODEL DEVELOPMENT. 42

3.3.1 ASSUMPTIONS. 42

3.3.2 SIMULATION MODEL. 43

3.3.3 UNITS IN THE SIMULATION MODEL. 43

3.4 PROCESS OPTIMIZATION.. 44

CHAPTER FOUR. 46

4.1 PROCESS MODELLING RESULTS. 46

4.1.1 ASPEN PLUS. 46

4.1.2 HPCC RESPONSE OPTIMIZATION:48

4.1.3 UREA REACTOR RESPONSE OPTIMIZATION.. 57

4.2 DISCUSSION OF RESULTS. 66

4.2.1 ASPEN PLUS SIMULATION.. 66

4.2.2 HPCC RESPONSE OPTIMIZATION.. 66

4.2.3 UREA REACTOR RESPONSE OPTIMIZATION.. 70

CHAPTER FIVE. 76

5.1 CONCLUSION.. 76

5.2 RECOMMENDATION.. 77

REFERENCES. 78

APPENDIX. 82