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Engineering Has a New Material for Hot Gas Cleanup:
Final Technical Report for July 1, 1999 to June 30, 2003

Wheelock, T. D.
Doraiswamy, L. K.
Constant, K. P.
Satrio, Justinus A.

Iowa State University

In this pdf format, this document has 114 pages and is 3.13MB.

Table of Contents

DISCLAIMER ii
ABSTRACT iii
LIST OF GRAPHICAL MATERIAL vii
INTRODUCTION 1
EXECUTIVE SUMMARY 3
LITERATURE REVIEW 5
  HOT GAS DESULFURIZATION 5
GAS-SOLID REACTION MODELS 7
  Choice of Model for the Present Reaction 10
 
EXPERIMENTAL 11
  MATERIALS 11
SORBENT PREPARATION 14
SORBENT CHARACTERIZATION 16
  Sorbent Capacity 16
Compressive Strength 18
Attrition and Abrasion Resistance 18
Surface Area Analysis 19
Density and Porosity Measurements 19
Chemical Composition and Structure 20
 
RESULTS AND DISCUSSION 20
  INITIAL DEVELOPMENT AND CHARACTERIZATION 20
  Shell Formulation 21
Core-in-Shell Pellets 24
Properties of Core-in-Shell Pellets 26
Core-in-Shell Pellet Structure 28
Conversion of CaSO4 to CaO in Plaster-based Cores 29
Sorbent Characteristics 32
SORBENT DEVELOPMENT 39
  Effect of H2S Decomposition on Testing 40
Effects of Different CaO Sources 44
Changes in Physical Properties During Multicycle Testing 48
Extended Multicycle Sulfidation and Regeneration Tests 54
High Temperature Stability of Sorbent Materials 57
SHELL DEVELOPMENT 67
DEVELOPMENT OF A MODEL FOR THE ABSORPTION PROCESS 84
  Experimental Results 84
 
CONCLUSIONS 98
REFERENCES 100
 
APPENDIX 104
  PUBLICATIONS 104
PRESENTATIONS 105
 
LIST OF GRAPHICAL MATERIAL
Figure 1 Effect of composition on the force required to break the calcined tablets made with a mixture of T-64 alumina and A-16 SG alumina powders 23
Figure 2 Effect of limestone concentration on the force required to break the calcined tables made with 3:2 ratio of T-64 alumina to A-16 SG alumina 23
Figure 3 Micrographs of a freshly made limestone-based pellet, i) section of an entire pellet at x17, ii) the shell at x110, iii) the core at x110, and iv) the shell at x1000 29
Figure 4 Micrographs of a fired limestone-based pellet, i) section of an entire pellet at x17, ii) the shell at x 110, iii) the core at x110 30
Figure 5 Decomposition of CaSO4 in various pellets by a cyclic oxidation and reduction process conducted at 1343 K (1070EC). 31
Figure 6 Replicate runs with pellet cores made of either DAP plaster of Paris or limestone. Absorption was conducted with 1.1%H2S at 1153 K (880°C) 31
Figure 7 Effect of shell thickness on the abosrbtion capacity of limestone-based, core-in-shell pellets. Absorption was conducted with 1.1% H2S at 1153 K (880°C) 34
Figure 8 Effect of shell thickness on absorption capacity of plaster-based, core-in-shell pellets. Absorption was conducted with 1.1% H2S at 1153 (880°C) 34
Figure 9 Effect of H2S concentration on absorption rate of limestone-based, core-in-shell pellets. Runs were conducted at 1153 (880°C) 36
Figure 10 Effect of H2S on concentration on absorption rate of plaster-based, core-in-shell pellets. Runs were conducted at 1153 K (880°C) 36
Figure 11 Effect of H2S concentration on initial global conversion rate for different types of core-in-shell pellets at 1153 K (880°C) 37
Figure 12 Effect of temperature on absorption rate of limestone-based, core-in-shell pellets. Runs were conducted with 1.1% H2S in nitrogen 38
Figure 13 Effect of temperature on absorption rate of plaster-based, core-in-shell pellets. Runs were conducted with 1.1% H2S in nitrogen. 38
Figure 14 Results of a typical multicycle sulfidation and regeneration test of a core-in-shell pellet using 1.6 vol.% H2S and 98.4 vol % N2 for sulfidation 41
Figure 15 Results of a multicycle sulfidation and regeneration test of a limestone pellet core using 1.0 vol % H2S, 24.0 vol % H2, and 75.0 vol % N2 for sulfidation 41
Figure 16 Specific absorption capacity of pure CaCO3 and limestone pellet cores sulfided with 1.0 vol % H2, and 75 vol % N2 at 1153 K (880°C) 46
Figure 17 Specific absorption capacity of pellet cores derived from different materials and sulfided with 1.0 vol % H2S, 24 vol % H2 and 75 vol % N2 at 1153 K (880°C) 46
Figure 18 Specific surface area of two different types of pellet cores at different stages of preparation and usage. 49
Figure 19 Apparent porosity of two different types of pellet cores at different stages of preparation and usage. 53
Figure 20 Apparent density of two different pellet types of cores at different stages of preparation and usage 53
Figure 21 Specific absorption capacity of different pellet cores repeatedly sulfided and regenerated using 1.0 vol % H2S, 24 vol % H2, and 75 vol % N2 for sulfidation at 1153 K (880°C) and using 13 vol % O2/9 vol % H2 for regeneration at 1323 K (1050°C) 55
Figure 22 Relative absorption capacity of different pellet cores repeatedly sulfided and regenerated using 1.0 vol % H2S, 24 vol % H2 and 75 vol % N2 for sulfidation at 1153 K (880°C) and using 13 vol % O2/9 vol % H2 for regeneration at 1323 K (1050°C) 55
Figure 23 Specific absorption capacity of two different pellet cores repeatedly sulfided at 1153 K (880°C) and regenerated at 1323 K (1050°C) 56
Figure 24 Results of a multicycle CO2 absorption test with an Iowa limestone pellet. 60
Figure 25 Results of a multicycle CO2 absorption test with a dolime pellet 60
Figure 26 Results of a multicycle absorption test with a pellet made from coprecipitated CaCO3 (90%) and SrCO3 (10%) 62
Figure 27 The specific absorption capacity of different materials for CO2 at 1023 K (750°C) 62
Figure 28 The relative CO2 absorption capacity of pellets prepared from different materials at 1023 K (750°C) 63
Figure 29 The limestone derived sorbent after eight cycles of absorption at 750°C 64
Figure 30 The sorbent derived from the B-mix of limestone (98%) and SrCO3 (2%) after eight absorption cycles at 750°C 65
Figure 31 The sorbent derived from the coprecipitated mixture of CaCO3 (90%) and SrCO3 (10%) after eight absorption cycles at 750°C 66
Figure 32 The sorbent derived from dolime after eight absorption cycles at 750°C 67
Figure 33 Response of pelletized shell material to sulfidation and regeneration 68
Figure 34 Results of a multicycle sulfidation and regeneration test with six core-in-shell pellets from batch 8. 75
Figure 35 Effects of shell composition and thickness on compressive strength of core-in-shell pellets. 77
Figure 36 Results of a typical sulfidation and regeneration test of a pellet core using 1.0 vol % H2S and 24 vol % H2 for sulfidation 86
Figure 37 Micrograph of an incompletely sulfided, 3.2 mm diameter pellet core: (i) SEM view, (ii) sulfur map, and (iii) calcium map 86
Figure 38 Micrograph of a highly sulfided, 4.4 mm diameter core-in-shell pellet: (i) SEM view, (ii) sulfur map, (iii) calcium map, and (iv) aluminum map. 88
Figure 39 Results of fitting the shrinking core model to the unadjusted conversion data for a pellet core sulfided with 1.0 vol % H2S and 24 vol % H2 at 1153 K (880°C) 88
Figure 40 Comparison of adjusted experimental conversion and the fitted model conversion for pellet no. 2 sulfided with 1.0 vol % H2S and 24 vol % H2 at 1153 K (880°C) 93
Figure 41 Comparison of adjusted experimental conversion and predicted conversion for pellet no. 2 sulfided with 1.0 vol % H2S and 24 vol % H2 at 1153 K (880°C) 93
Figure 42 Comparison of adjusted experimental conversion and predicted conversion for a pellet sulfided with 0.5 vol % H2S and 24 vol % H2 at 1153 K (880°C) 95
Figure 43 Comparison of predicted and experimental values of adjusted conversion for core-in-shell pellet no. 3 sulfided with 1.0 vol % H2S and 24 vol % H2 at 1153 K (880°C) 95