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Advanced Second Generation Ceramic Candle Filters,
Final Report - April 23, 2004

M. A. Alvin

Siemens Westinghouse Power Corporation

In this pdf format, this document has 102 pages and is 5.5MB.

Table of Contents

ABSTRACT  
 
EXECUTIVE SUMMARY  
 
1 INTRODUCTION 1
2 POROUS CERAMIC FILTER MATRICES 4
  2.1 Monolithic Oxide-Based Ceramic Matrices 4
2.2 Monolithic Nonoxide-Based Ceramic Matrices 15
2.3 Second-Generation Oxide-Based Ceramic Matrices 26
2.4 Second-Generation Nonoxide-Based Ceramic Matrices 31
3 FIELD TESTING 38
  3.1 Overview 38
3.2 Foster Wheeler PCFBC Test Campaigns 39
4 FILTER FAILURE MECHANISMS 44
5 ACCELERATED LIFE TESTING PROGRAMS 54
  5.1 Assessment of Advanced Second Generation Candle Filters - Phase I 54
5.2 Extended Accelerated Life Testing - Phase II 58
  5.2.1 Accelerated Pulse Cycle Exposure 59
5.2.2 Thermal Transient Testing 60
5.2.3 Material Characterization 61

5.3

 Accelerated Life Testing and High Temperature Corrosion Studies - Phase III 67
6 SUMMARY AND CONCLUSIONS 78
7 REFERENCES 86
8 ACKNOWLEDGEMENTS 88
 
APPENDIX A - FILTER MATERIAL STRENGTH
 
TABLES
1 Hot Gas Filter Materials 2
2 Porous Filter Technology Development 3
3 Field and Extended Life Testing 39
4 Summary of PCFBC Testing in 1995-1996 40
5 Summary of PCFBC Testing in 1997 42
6 Advanced Second Generation Candle Filter Material Stability and Performance Evaluation 54
7 Summary of the Extended Filter Life Test Program - Phase I 56
8 Extended Filter Life Testing - Phase II 60
9 Residual Filter Element Room and High Temperature Strength 62
10 Residual Filter Element Room and High Temperature Load Bearing Capabilities 63
11 Residual Filter Element Room and High Temperature Material Diametral Strength and Load Bearing Capabilities 64
12 Candle Filter Array - Steady State, Accelerated Pulse Cycling and Thermal Transient Testing - Phase III 68
13 Candle Filter Array - High Temperature Corrosion Testing - Phase III 71
14 Porous Ceramic Filter Failure Mechanisms 81
A-1 Residual Room and High Temperature Strength after PFBC/PCFBC and Accelerated Life Testing  
 
FIGURES
1 Porous candle and cross flow filter elements 1
2 Variation in the candle filter flange geometry 5
3 Variations in the candle filter flange and filter wall thickness 6
4 Variation in the candle filter closed end geometry 7
5 Hot gas filter development - Geometric design concepts 8
6 High temperature particulate filtration 8
7 As-manufactured Coors P-100A-1 alumina/mullite filter matrix 9
8 Extensive mullitization within the Coors P-100A-1 filter matrix with extended operation in PFBC/PCFBC applications 9
9 Crystallization of the Coors P-100A-1 alumina/mullite filter matrix resulted during PFBC/PCFBC operation leading to extensive mullite formation along the surface of pore cavities within the filter element 10
10 Anorthite formation along the surface of the pore cavities, and mullitization within the ligaments of the PFBC/PCFBC-exposed Coors P-100A-1 alumina/mullite filter matrix 11
11 Silica phase enrichment at the tips of the blunted mullite rods along the pulse cycled surface of the PFBC/PCFBC-exposed Coors P-100A-1 alumina/mullite filter matrix 11
12 As-manufactured Blasch mullite bonded alumina filter matrix 12
13 Mullitization resulting within the Blasch filter media with extended PFBC/PCBFC operation 13
14 As-manufactured Ensto mullite bonded alumina filter matrix 13
15 Mullite formation along the outer surface of the alumina grains contained within the as-manufactured Ensto filter matrix 14
16 Mullite ligament formation bonding adjacent alumina grains together within the as-manufactured Ensto filter matrix 14
17 Vacuum infiltrated chopped fibers contained within the IF&P Fibrosic™ filter matrix 15
18 Morphology of the as-manufactured Schumacher Dia Schumalith clay bonded silicon carbide filter matrix 16
19 Residual strength of the PFBC/PCFBC-aged and extended life-tested porous ceramic filter elements 17
20 Coalescence and crystallization of the binder coating that encapsulated the silicon carbide grains within the Schumacher filter matrix after 3038 hours of PFBC operation 18
21 Micrograph montage illustrating coalescence and crystallization of the binder coating along the surface of the silicon carbide grains, as well as within the ligament bond posts of the PFBC- exposed Pall clay bonded silicon carbide filter matrix 18
22 Micrograph montage illustrating the thickness of the silica-enriched layer that formed along the outer surface of the silicon carbide grains within the Pall filter matrix after PFBC operation 19
23 Formation of mullite and silica within the aluminosilicate binder phase that encapsulated the silicon carbide grains within the PFBC/PCFBC-exposed Schumacher filter matrix 19
24 Morphology of the fresh fractured Pall filter matrix after PFBC/PCFBC operation 20
25 Formation of a silica-enriched phase along the surface of the silicon carbide grains, as well as at the base of the filter ligaments within the PFBC/PCFBC - exposed Pall and Schumacher filter matrices 21
26 Crystallization resulting at the base of the fresh fractured ligament in the PFBC-exposed Schumacher filter matrix 22
27 Outgassing of species along the surface of the PFBC/PCFBC - exposed Pall filter matrix leading to the formation of voids along the silica-enriched crystallized surface 22
28 As-manufactured IF&P recrystallized silicon carbide filter matrix 23
29 Formation of silica along the outer surface of the IF&P recrystallized silicon carbide filter matrix 23
30 Dendritic mullite formation along the surface of the simulated PFBC- exposed IF&P recrystallized silicon carbide grains 24
31 As-manufactured Ultramet CVI-SiC reticulated foam 25
32 DuPont PRD-66 filament would filter matrix 26
33 Filaments contained with the as-manufactured DuPont PRD-66 filter matrix 26
34 Cross-sectioned filament within the DuPont PRD-66 filter matrix 27
35 Crystalline features along the outer surface of the fiber replicas of the DuPont filter matrix 28
36 Nextel™ filament bundles contained within the McDermott CFCC candle filter 29
37 Filament fiber bundles embedded within the chopped fiber matrix along the o.d. surface of the as-manufactured McDermott CFCC filter element 29
38 As-manufactured Techniweave CFCC filter element 30
39 3M CVI-SiC filter matrix 31
40 CVI-SiC layer deposited along the outer surface of the 3M Nextel™ 312 structural support triaxial braid 32
41 Sections of the 3M CVI-SiC composite candle filter after PFBC or PCFBC operation 32
42 Crack formation along the silica-enriched infiltrated layers that surrounded the Nextel™ 312 fibers in the triaxial support braid of the 3M composite filter matrix after 2815 hours of exposure above the Siemens Westinghouse APF system tubesheet at AEP 33
43 Morphology of the cross-sectioned 3M CVI-SiC composite filter material after 400 hours of exposure at 870°C (1600°F) to 20 ppm NaCl/5-7% steam/air 34
44 DuPont SiC-SiC CFCC filter architecture 35
45 Morphology of the DuPont SiC-SiC CFCC hybrid filter matrix after accelerated pulse cycle testing in SWPC's PFBC simulator test facility 36
46 SWPC APF system at the AEP PFBC Tidd demonstration plant in Brialliant, OH 38
47 Thermal fatigue of the Coors P-100A-1 alumina/mullite filter matrix 44
48 Coors p-100A-1 alumina/mullite closed end cap 44
49 Crack formations at the base of the Pall Vitropore filter flange as a result of high temperature creep during operation at AEP 45
50 Failure of the porous ceramic filter elements as the result of ash bridging within the filter array 46
51 Failure of the vacuum infiltrated chopped fibrous candle filters 46
52 Failure of the thinner walled 3M CFCC filter element flange 47
53 Failure of the DuPont PRD-66 filter element 48
54 Failure of the Techniweave CFCC filter element after operation in the PCFBC test facility in Karhula, Finland 48
55 Failure of the 3M oxide-based CFCC filter elements 49
56 Removal of fibers along the outer surface of the McFermott CFCC filter element 49
57 Critical inserts within the McDermott CFCC filter element 50
58 Crystallization of the Nextel™ fibers within the oxide-base CFCC filter matrices 51
59 Failure of the 3M nonoxide-based CFCC filter element 52
60 Failure of the DuPont SiC-SiC CFCC filter matrix 53
61 Residual room and process temperature compressive strength of the various ceramic candle filter materials as a function of field and extended simulated PFBC accelerated life testing 65
62 Residual room and process temperature tensile strength of the various ceramic candle filter materials as a function of field and extended simulated PFBC accelerated life testing 66
63 Ceramic and metal candle filter array 67
64 Temperature profile during thermal transient testing 69
65 Filter elements at the conclusion of steady state, accelerated pulse cycling and thermal transient testing 70
66 Failure of the Blasch mullite bonded alumina candle filter after 282 hours of operation in the 840°C (1550°F), simulated PFBC process gas environment containing gas phase sulfure and alkali (Test Segment No. 1) 71
67 Candle filters at the conclusion of Test Segment No. 2 - 486 hours of exposure at 840°C (1550°F) in the simulated PFBC process gas environment containing gas phase sulfure and alkali 72
68 Room temperature gas flow resistance through the porous filter elements 73
69 Schumacher clay bonded silicon carbide FT20 filter matrix after 204 hours of operation in the gas phase alkali and sulfur-laden, 840°C (1550°F), simulated PFBC process gas environment 74
70 Morphology of the Filtros recrystallized silicon carbide filter matrix after 486 hours of operation in the gas phase alkali and sulfur-laden, 840°C (1550°F), simulated PFBC process gas environment 74
71 Morphology of the Blasch filter matrix after 282 hours of exposure to the 840°C (1550°F), gas phase alkali and sulfur-laden, simulated PFBC process gas environment 75
72 Microstructure of the DuPont PRD-66 filter matrix after 486 hours of exposure to the gas phase alkali and sulfur-laden, 840°C (1550°F), simulated PFBC process gas environment 76
73 Microstructure of the McDermott CFCC filter matrix after 486 hours of exposure to the gas phase alkali and sulfur-laden, 840°C (1550°F), simulated PFBC process gas environment 76
74 Microstructure of the Techniweave CFCC filter matrix after 486 hours of exposure to the gas phase alkali and sulfur-laden, 840°C (1550°F), simulated PFBC process gas environment 77
75 Microstructure of the Pall FeAl filter matrix after 204 hours of operation in the gas phase alkali and sulfur-laden PFBC process gas environment 77
76 Porous hot gas filter material technology development 78
77 Porous monolithic nonoxide-based ceramics used for hot gas filter technology development 79
78 Porous monolithic oxide-based ceramics used for hot gas filter technology development 80
79 Porous second-generation oxide-based ceramics used for hot gas filter technology development 82
80 Porous second generation nonoxide-based ceramics used for hot gas filter techonology development 83
81 Recommended maximum operating temperatures for hot gas filter material stability 84