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Advanced Hot Gas Filter Development
September 29, 1994 to September 30, 2000

Connolly, E. S.
Forsythe, G. D.

Table of Contents

Report

1. EXECUTIVE SUMMARY 1
2. INTRODUCTION 2
3. TECHNICAL RESULTS AND DISCUSSION 5
3.1 Background Technology 5
3.2 Material Qualification (Subtask 3.1) 7
  3.2.1 Improving the Surface Membrane 8
3.2.2 Development of a Dual Membrane Candle Filter 10
3.2.3 Mechanical Testing 12
3.2.4 Strengthened Flanges 15
3.2.5 Filtration and Permeability Testing 18

3.3

Field Testing of "Baseline" PRD-66 Filter Elements 20
  3.3.1 Tidd Test Segment 4 20
3.3.2 Tidd Test Segment 5 21
3.3.3 Analysis of Field Exposed Elements (Subtask 3.4) 21

3.4

Development of High Efficiency Membranes 31
  3.4.1 Membrane Development for the Outside Diameter (OD) Surface (Subtask 3.1) 31
3.4.2 Membrane Development for the Inside Diameter (ID) Surface (Subtask 3.1.1) 35

3.5

Manufacturing Hot Gas Filters (Task 4) 41
  3.5.1 Raw Materials Plan (Subtask 4.1) 41
3.5.2 Process Instrumentation (Subtask 4.2) 41
3.5.3 Process Variables Experiments (Subtask 4.3) 42
3.5.4 Process Capability Demonstration (Subtask 4.4) 49
3.5.5 Equipment Analysis and Improvement (Subtask 4.5) 54
3.5.6 Redesign of Prototype Winding Equipment (Subtask 4.7 56

3.6

Field Testing of "Improved" PRD-66 Filter Elements 58
  3.6.1 High Temperature High Pressure (HTHP) Testing at W-STC 58
3.6.2 PCFBC Exposure at Karhula 63
3.7 Manufacturing 50 Filters (Task 5) 77
3.8 Field Testing of Task 5 Filters (Subtask 3.4.1) 78
  3.8.1 PSDF Exposure History 78
3.8.2 Failure Characterization and Investigation 80
3.8.3 Non-Destructive Evaluation of PRD-66 Filters 114
4. CONCLUSIONS 116
5. RECOMMENDATIONS 120
6. ACKNOWLEDGEMENTS 121
7. REFERENCES 122
LIST OF FIGURES
1 Schematic of the basic process for winding PRD-66 cylindrical structures 6
2 Schematic of the PRD-66 membrane winding process 6
3 Phase diagram including PRD-66 composition 7
4 Impact of three PRD-66 variables on backpressure (DP), where "N" is the number of samples 9
5 Impact of inside diameter membrane on backpressure (DP), where "N" is the number of samples 11
6 Typical Load Displacement Curve for PRD-66 filter segment 12
7 O-rings AFTER (left) and BEFORE (right) diametrical compression testing 13
8 Weibull Analysis of PRD-66 candle filter segment 14
9 Strain rate dependence of o-ring crushing test. 15
10 O-ring diametrical compressive strength versus ring weight 16
11 O-Ring diametrical compressive strength vs. amount & viscosity of infiltrate 17
12 Load Displacement Curve for infiltrated PRD-66 filter segment 17
13 W-STC Room Temperature Gas Flow Resistance measurements of 1.5-meter PRD-66 filter elements with various membranes 19
14 "Divots" in PRD-66 filter tested in Tidd Test Segment 5. 21-29
15 White deposit (middle left) in vicinity of "divot" (upper right). 24
16 Unit-cell size of magnesium sulfate versus state of hydration. 24
17 Particle Infiltration Test (PIT) Device 26
18 PIT-exposed sample viewed in transmitted light. 26
19 Untested sample viewed in transmitted light. 26
20 Exaggerated illustration of a PRD-66 delamination 27
21 Original wound membrane 31
22 Membrane with added filler 31
23 Modified membrane with PIT rating of "10" 32
24 Hole in membrane, undetectable under direct light 32
25 Hole in membrane, detectable under transmitted light 32
26 Hole in membrane after 25 PIT cycles, viewed in transmitted light 33
27 PRD-66M membrane, measured pore distribution 34
28 PRD-66M flow resistance for 1.5-meter candles. 34
29 PRD-66C membrane, measured pore distribution 34
30 PRD-66C flow resistance for 1.5-meter candles. 34
31 Particle Infiltration Test device for ID membranes 36
32 ID P.I.T. evaluation of original "hoop-only dual membrane" filter (1995) 36
33 Standard filter support scheme during membrane-filler application 37
34 Cantilevered filter support for membrane-filler application 37
35 ID P.I.T. evaluation of "slip-cast ID membrane" filter (no membrane on OD) 39
36 Device for removing excess membrane from the inside surface of a filter 40
37 Impact of membrane weight and type on backpressure 47
38 PRD-66 Candle Filter dimensions 49
39 Tip of original steel mandrel 54
40 Original hoop membrane 57
41 Hoop winding with modified winder 57
42 PRD-66C - Room temperature gas flow resistance 59
43 PRD-66M - Room temperature gas flow resistance 59
44 Gas flow resistance of as-manufactured and HTHP - exposed PRD-66M elements 60
45 Gas flow resistance of as-manufactured and HTHP - exposed PRD-66C elements 60
46 Karhula-exposed PRD-66C filters 64
47 Outside diameter of Karhula - exposed element before ash removal 65
48 Inside diameter of Karhula - exposed element before ash removal 65
49 Differential pressure of Karhula filters measured by Foster Wheeler 66
50 Wall interior of Karhula-exposed candle #577 67
51 Close-up of #577 - OD surface and 1-2mm below 67
52 300X - UNEXPOSED candle surface 68
53 300X - EXPOSED candle surface 68
54 1,000X - EXPOSED candle surface 69
55 UNEXPOSED CANDLE, cross-section of membrane filler (300X) 69
56 EXPOSED CANDLE, cross-section of membrane filler (300X0 70
57 25X, fast-fracture - UNEXPOSED CANDLE, interior of support wall 70
58 25X, fresh-fracture - EXPOSED CANDLE, interior of support wall 71
59 50X, fast-fracture - UNEXPOSED CANDLE, interior of support wall 71
60 50X, fast-fracture - EXPOSED CANDLE, interior of wall support 72
61 UNEXPOSED CANDLE, individual "yarn bundle" (300X) 73
62 EXPOSED CANDLE, individual "yarn bundle" (300X) 73
63 UNEXPOSED CANDLE, individual "yarn bundle" (1,000X) 74
64 EXPOSED CANDLE, individual "yarn bundle" (1,000X) 74
65 Aftermath of Oct'98 thermal event in the lower plenum at the PSDF 79
66 C740 (T12), 18-19" from open end 82
67 C749 (T33), 12" from open end 82
68 Spalled area of Filter #C740, 18" from open end, no other similar damage 82
69 Spalled area of Filter #C749, 12" from open end, similar damage 90 away 82
70 Damage resulting from impact testing of Filter C633, Alumina Lot #1, 1360 exposure hours 84
71 Damage resulting from impact testing of Filter C740, Alumina Lot#2, 636 exposure hours 84
72 Surface Damage Rating = 1 87
73 Surface Damage Rating = 4 87
74 C756 (T-31) broke during reinstallation 89
75 C750 (B-49) with fine crack at base of tapered region of flange 89
76 Description of flange contours as determined by Optical Comparator 90
77 PRD-66 Flange Measurement Technique 92
78 Standard-shape PRD-66 flange 93
79 Modified PRD-66 flange using manual techniques 93
80 C750, similar to C731 and C752 94
81 C749 (T33), flange end 94
82 Broken end of Filter C752, with deep chip 1 " below the break 95
83 C745 (B-54) 96
84 C633, broke removing filter-nut 96
85 Box Plot of o-ring compressive strength for as-manufactured filters 97
86 Average o-ring compressive strength for as-manufactured filters, 98
87 Box Plot of o-ring compressive data grouped by alumina lot number. 99
88 X-ray Diffraction Comparison of Filter #638 (Alumina Lot #1) and Filter #713 (Alumina Lot #2) shows no differences in crystalline phases 100
89 Cutting plan for tensile coupons from PRD-66C "as-manufactured filters". 102
90 Filter cross-section depicting geometry of tensile coupons 102
91 Axial Tension stress/strain curves for unexposed filters made with Alumina Lot#1 103
92 Axial Tension stress/strain curves for unexposed filters made with Alumina Lot#2 103
93 Microstructure of PRD-66C Filter #C567, 500X 104
94 Microstructure of PRD-66C Filter #713, 500X 105
95 Microstructure of PRD-66C Filter #C752, 500X 106
96 Fresh-fracture SEM of PRD-66C Filter #C567 (high strength) at 500X 107
97 Fresh-fracture SEM of PRD-66C Filter #C713 (low strength) at 500X 107
98 Fresh-fracture SEM of #C567 in high-alumina region at 1,000X 108
99 Fresh-fracture SEM of #C567 in low-alumina region at 1,000X 108
100 Alumina content versus average o-ring diametrical compressive strength for as-manufactured PRD-66 filters made with Alumina Lot #2 109
101 PRD-66 4-point flex coupons - cross-section 111
102 PRD-66 4-point flex coupons - side-cut view 111
103 4-Point Flex Test set-up of PRD-66 coupons from regions within 4" of the flange 111
104 Maximum 4-Point Load for the Flex Testing of PRD-66 filters in three different regions: infiltrated zone, transition zone, and uninfiltrated zone 112
105 Load-Displacement Curves for 4-point flex tests in the "transition (edge) zones" 113
106 Preliminary NDE results on PRD-66 hot gas filters, comparing ANL's Stress Wave Value to the o-ring diametrical compressive strength of the same filter. 114
107 Stress Wave Factor (SWF) trend along the length of PRD-66 filter C856 115
TABLES
1 Impact of "intermediate" matrix ratio on backpressure (DP) at 5 scfm 10
2 Impact of dual membranes on backpressure (DP) at 5 scfm 11
3 Average o-ring diametrical compressive strength ("n" is the number of samples) 14
4 Comparison of test conditions in Tidd Test Segments 4 and 5 22
5 Process variables investigated for winding filter support 43
6 Observed impact of process changes on support winding 43
7 Impact of grit-size and binder content on backpressure 46
8 Impact of binder content on backpressure of PRD-66C 47
9 Process Capability Demonstration 50
10 Process Capability Summary 51
11 W-STC Room temperature and process strength of PRD-66 elements 61
12 W-STC Ultimate load applied during strength characterization 62
13 W-STC Material properties of PRD-66 elements 62
14 DLC Diametrical compression testing of HTHP-exposed & unexposed candles 62
15 Karhula PCFBC test conditions 63
16 O-ring diametrical compressive testing of Karhula-exposed & unexposed candles 75
17 Power Systems Development Facility (PSDF0 Nominal Operating Conditions 78
18 Damage Resulting from Impact Testing of Exposed Filters 85
19 Design of Impact Damage Experiment 85
20 Effect of Alumina Content and Lot on Surface Damage Rating 87
21 Effect of Alumina Content and Lot on Depth of Damage 88
22 Nominal Crystalline Phase Composition of PRD-66 100
23 O-ring Strength fo As-Manufactured PRD-66 Filter 101
APPENDICES  
1 Ceramic Hot-Gas Filter (1.19MB)  
2 DLC Raw Materials Specification Form (21.2KB)  
3 Summary Report - Part 1, Pages i - 16, 5.63MB
Summary Report - Part 2, Pages 17 - 28, 6.27MB
Summary Report - Part 3, Pages 29 - 34, 5.44MB