Part 1, Pages 1 - 95, 4.52 MB

Executive Summary

ii

Table of Contents

v

1.

Background Statement

1

2.

Sulfidation of Limestone-Derived Calcines

5

2.1

Introduction

5

2.2

Materials and Procedures

8

2.3

Calcination Experiments

13

2.4

Sulfidation Experiments

18

2.5

Experimental Results and Model Predictions

29

2.6

Summary and Conclusions

41

2.7

Notation

43

2.8

Literature References

43

3.

Sulfation of High Purity Limestones Under Simulated PFBC Conditions

46

3.1

Introduction

46

3.2

Materials and Procedures

51

3.3

Reactivity Evolution Results

52

3.4

Pure Structure Results

64

3.5

Discussion

71

3.6

Conclusions

76

3.7

Notation

78

3.8

Literature References

79

4.

A Variable Diffusivity Shrinking-Core Model and Its Application to the Direct Sulfation of Limestones

82

4.1

Introduction

82

4.2

Model Equations and Parametric Sensitivity

84

4.3

Parameter Estimation Procedure

92

 Part 2, Pages 96 - 193, 4.05 MB

4.4

Results and Discussion

96

4.5

Summary and Concluding Remarks

114

4.6

Notation

116

4.7

Literature References

118

5.

Effective Diffusivity Changes During Calcination, Carbonation, Recalcination, and Sulfaction of Limestones

119

5.1

Introduction

119

5.2

Materials and Sample Preparation

122

5.3

Pulse Chromatographic Experiments and Data Analysis

125

5.4

Experimental Results and Discussion

131

5.5

Measures Vs. Theoretically Predicted Diffusivities

148

5.6

Summary and Concluding Remarks

153

5.7

Notation

155

5.8

Literature References

156

6.

Experimental and Theoretical Investigation of Factors Affecting the Direct Limestone-H₂S Reaction

158

6.1

Introduction

158

6.2

Materials and Experimental Procedures

161

6.3

Reactivity Results

163

6.4

Estimation of Kinetic Parameters

170

6.5

Effects and Structure of Product Layer

173

6.6

Product Layer Diffusivities and Discussion

180

6.7

Summary

189

6.8

Notation

191

6.9

Literature References

192

 Part 3, Pages 194 - 298, 4.41 MB

7.

Experimental Validation of A Mathematical Model For Fixed-Bed Desulfurization

194

7.1

Introduction

194

7.2

Materials

196

7.3

Apparatus and Procedure

197

7.4

Single Particle Behavior

200

7.5

Mathematical Model for a Fixed-Bed Reactor

204

7.6

Sulfidation Experiments in a Fixed-Bed Reactor and Model Predictions

211

7.7

Analysis of the Pore Structure of the Sulfided Sorbents

218

7.8

Summary and Conclusions

227

7.9

Notation

229

7.10

Literature References

231

8.

A Partially Overlapping Grain Model for Gas-Solid Reactions

233

8.1

Local Reaction and Structure Evolution Model

235

8.2

Structured Model Results

243

8.3

Results Under Internal Diffusional Limitations

252

8.4

Application to the Reaction of ZnO Sorbents with H2S

258

8.5

Summary and Further Remarks

260

8.6

Notation

263

8.7

Literature References

265

9.

Steady-State vs. Transient Measurement of Effective Diffusivities in Porous Media Using the Diffusion-Cell Method

267

9.1

Introduction

267

9.2

Description of the Diffusion-Cell System

271

9.3

Effective Diffusivities from Transient Experiments using Moments Matching

274

9.4

Comparison of the Homogenous and Inhomogeneous Model Responses in the Time Domain

278

9.5

Pore Interlinking and Mismatch between the Homogeneous and Inhomogeneous Model Responses

290

9.6

Summary and Concluding Remarks

294

9.7

Notation

298

9.8

Literature References

299