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发表于 2020-2-12 12:00:52
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contents
1 Scope ............................................................................................................................................................... 1
2 Normative References ...................................................................................................................................... 2
3 Terms, Defnitions, and Acronyms .................................................................................................................... 3
3.1 Terms and Defnitions ....................................................................................................................................... 3
3.2 Acronyms.......................................................................................................................................................... 5
4 Background of REAC Corrosion ....................................................................................................................... 5
4.1 History of Reactor Effuent System Corrosion Surveys .................................................................................... 5
4.2 Typical Hydroprocessing Units ......................................................................................................................... 6
4.3 Effuent Separation Designs ............................................................................................................................. 8
4.4 REAC System Corrosion .................................................................................................................................. 8
5 Strategies to Promote System Reliability ....................................................................................................... 11
5.1 General ........................................................................................................................................................... 11
5.2 Material Selection and Design ........................................................................................................................ 12
5.3 Establishing an Integrity Operating Window ................................................................................................... 12
5.4 Inspection Plans ............................................................................................................................................. 13
6 Process Variables Affecting Corrosion ........................................................................................................... 13
6.1 Ammonium Bisulfde Concentration ............................................................................................................... 13
6.2 Process Conditions at the Water Dew Point ................................................................................................... 14
6.3 Fluid Velocities ............................................................................................................................................... 14
6.4 Hydrogen Sulfde (H 2 S) Partial Pressure ........................................................................................................ 17
6.5 Flow Regime .................................................................................................................................................. 18
6.6 Chlorides ........................................................................................................................................................ 19
6.7 Cyanides ........................................................................................................................................................ 20
6.8 Other Process Variables ................................................................................................................................. 21
6.9 Wash Water .................................................................................................................................................... 21
6.10 Corrosion Inhibitors ........................................................................................................................................ 23
6.11 Air Cooler Fan Operations .............................................................................................................................. 24
6.12 Process Monitoring and Integrity Operating Windows (IOWs) ....................................................................... 24
7 Materials of Construction ................................................................................................................................ 26
7.1 General ........................................................................................................................................................... 26
7.2 Material Selection Criteria .............................................................................................................................. 27
8 Equipment-specifc Design Considerations .................................................................................................... 31
8.1 Fin Fan Air Coolers ......................................................................................................................................... 31
8.2 Shell-and-tube Trim Coolers ........................................................................................................................... 33
8.3 Hot High-pressure Separator (HHPS) ............................................................................................................ 34
8.4 Cold High-pressure Separator (CHPS) .......................................................................................................... 34
8.5 Heat Exchanger or Air Cooler Upstream of REAC ......................................................................................... 35
8.6 Piping and Valves ........................................................................................................................................... 36
9 Inspection of the REAC System ..................................................................................................................... 40
9.1 General ........................................................................................................................................................... 40
9.2 Reactor Effuent Air Coolers ........................................................................................................................... 41
9.3 Shell and Tube Heat Exchangers ................................................................................................................... 43
9.4 Piping ............................................................................................................................................................. 43
9.5 Pressure Vessels—Separators and Heat Exchanger Shells .......................................................................... 45
9.10 Use of Infrared Thermography for Monitoring REAC System Operations ...................................................... 45
10 Limitations and Recent Improvements in the Industry Knowledge Base ....................................................... 47
10.1 Experience ..................................................................................................................................................... 47
10.2 Recent Joint Industry Research ..................................................................................................................... 47
Annex A (normative) Process Calculations and Other Estimates ............................................................................ 50
Annex B (informative) Bibliography ......................................................................................................................... 58
Figures
1 Example Hydrotreating Unit Process Flow Diagram ........................................................................................ 7
2 Example Hydrocracking Unit Process Flow Diagram ....................................................................................... 7
3 Example Process Scheme with a CHPS .......................................................................................................... 9
4 Example Process Scheme with a CHPS and CLPS ........................................................................................ 9
5 Example Process Scheme with Two Separators, a HHPS and CHPS ........................................................... 10
6 Example Process Scheme with Four Separators ........................................................................................... 10
7 Curves Showing Effect of NH 4 HS Concentration on Corrosion of Carbon Steel through Small Orifice
(0.15 in.) Coupons ..........................................................................................................................................14
8 Isocorrosion Curves for Carbon Steel at Various NH 4 HS Concentrations and Velocities through Small
Orifice (0.15 in.) Coupons ..............................................................................................................................15
9 Tie-in Plot for Carbon Steel at 1 wt % NH 4 HS Concentrations and Various Velocities through Small Orifice
(0.15 in.) Coupons [130 °F (55 °C), 0 ppm Free Cyanide] .............................................................................16
10 Tie-in Plot for Carbon Steel at 25 wt % NH 4 HS Concentrations and Various Velocities through Small Orifice
(0.15 in.) Coupons [130 °F (55 °C), 0 ppm Free Cyanide]..............................................................................16
11 Curves Showing Effect of H 2 S Partial Pressure on Corrosion of Carbon Steel through Small Orifice
(0.15 in.) Coupons ...........................................................................................................................................17
12 Tie-in Plot for 316L SS at 1 wt % NH 4 HS Concentrations and Various Velocities through Small Orifice
(0.15 in.) Coupons [130 °F (55 °C)] ...............................................................................................................
18
13 Alloy 2205 REAC Failures as a Function of Ammonium Bisulfde Concentration and Total Pressure ........... 29
14 Relative Alloy Performance in Aqueous NH4HS Service ............................................................................... 31
15 Illustration of a Balanced and Unbalanced Inlet Piping Confguration ............................................................ 38
16 Cross-section of Internal Surface of Failed REAC Outlet Nozzle ................................................................... 42
17 Erosion-Corrosion of Carbon Steel Piping Elbow ........................................................................................... 44
18 IR Image of Water Wash Injection Locations .................................................................................................. 46
19 IR Image of Water Wash Injection Location ................................................................................................... 46
20 IR Image of the Top of the Air Cooler Tubes Showing Poor Water Wash Distribution .................................... 47
A.1 Estimating Ammonium Salt Deposition Temperature from Process Stream Composition .............................. 53
Tables
1 Factors Affecting REAC System Corrosion and Fouling .................................................................................. 2
2 Quality Parameters of Injected Wash Water ................................................................................................... 21
3 Suggested Process Variables to Consider for Monitoring or Inclusion in an Integrity Operating Window...... 25
4 Referenced Material Compositions ................................................................................................................ 27
5 Suggested Locations for IR Monitoring .......................................................................................................... 46
A.1 Reactor Effuent Mix ....................................................................................................................................... 50 |
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