MODELLING OF DOWNDRAFT GASIFIER USING COMPUTATIONAL

0,53

MB

FLUID DYNAMICS SOFTWARE-FLUENT

71

stron

5256

ID

University of Strathclyde

2003

rok

TABLE OF CONTENTS

ACKNOWLEDGEMENT ..i

ABSTRACT ..ii

CHAPTER 1 - INTRODUCTION ..1

1.1 BIOMASS RESOURCES ..1

1.2 SIGNIFICANCE OF CURRENT WORK ..2

1.3 BIOMASS GASIFIER ..3

1.4 OVERVIEW OF PROJECT TOPIC ..5

1.5 CONCISE PROJECT DEFINITION: MOTIVATION FOR CURRENT WORK ..6

1.6 AIM AND OBJECTIVES OF THE STUDY ..7

CHAPTER 2 – THEORY AND LITERATURE REVIEW ..8

2.1 INTRODUCTION ..8

2.2 THEORY OF BIOMASS GASIFICATION ..8

2.2.1 CONCEPT OF GASIFICATION AND PYROLYSIS ..8

2.2.2 GASIFICATION EQUATION ..10

2.3 MODEL ..11

2.3.1 CHARACTERISTICS OF BIOMASS GASIFIER ..11

2.3.2 GAS PRODUCTION FROM GASIFIER ..12

2.4 COMBUSTION REACTION MECHANISMS ..14

2.5 THEORETICAL CONSIDERATIONS ON CFD ..16

2.5.1 PRE-PROCESSOR ..16

2.5.2 SOLVER ..17

2.5.3 POST-PROCESSOR

2.6 PROBLEM SOLVING ..18

CHAPTER 3 – METHODOLOGY ..19

3.1 INTRODUCTION ..19

3.2 GASIFIER MODELLING USING CFD SOFTWARE ..19

3.2.1 FLUENT 5.5 ..19

3.2.1.1 PRE-PROCESSING ..19

3.2.1.2 SOLVER ..20

3.2.1.3 POST-PROCESSING ..20

3.3 MODEL SETTING ..21

3.3.1 DIMENSION ..21

3.3.1.1 DOWNDRAFT GASIFIER ..23

3.3.1.2 PRESSURISED DOWNDRAFT GASIFIER ..26

3.4 MODELLING PROCEDURE ..27

CHAPTER 4 - RESULT ANALYSIS AND DISCUSSION ..28

4.1 INTRODUCTION ..28

4.2 MODEL DESCRIPTION ..28

4.3 RESULT ANALYSIS FROM DOWNDRAFT GASIFIER ..30

4.3.1 FIRST-ORDER DISCRETIZATION ..30

4.3.2 SECOND-ORDER DISCRETIZATION ..31

4.4 DOWNDRAFT GASIFIER CONTOUR RESULTS ..33

4.4.1 PROFILE FOR FIRST-ORDER DISCRETIZATION ..33

4.4.1.1 TEMPERATURE & PRESSURE CONTOUR ..34

4.4.1.2 TEMPERATURE & PRESSURE DISTRIBUTION ..36

4.5 RESULT ANALYSIS FROM PRESSURISED DOWNDRAFT GASIFIER ..39

4.5.1 FIRST-ORDER DISCRETIZATION ..39

4.5.2 SECOND-ORDER DISCRETIZATION ..39

4.6 PRESSURISED DOWNDRAFT GASIFIER CONTOUR RESULTS ..40

4.6.1 PROFILE FOR FIRST-ORDER DISCRETIZATION ..40

4.6.1.1 TEMPERATURE & PRESSURE CONTOUR ..40

4.6.1.2 TEMPERATURE & PRESSURE DISTRIBUTION ..42

CHAPTER 5 – CONCLUSION & RECOMENDATIONS ..46

REFERENCES ..48

APPENDICES ..50

APPENDIX 1.1: LIST OF GASIFIER ..50

APPENDIX 1.2: SUMMARY - FIRST-ORDER DISCRETIZATION FOR DOWNDRAFT

GASIFIER...52

APPENDIX 1.3: SUMMARY - FIRST-ORDER DISCRETIZATION FOR PRESSURISED

DOWNDRAFT GASIFIER. ..60