1、Design, Materials, Fabrication, Operation, and Inspection Guidelines for Corrosion Control in Hydroprocessing Reactor Effluent Air Cooler (REAC) SystemsAPI RECOMMENDED PRACTICE 932-BSECOND EDITION, MARCH 2012ERRATA, JANUARY 2014Design, Materials, Fabrication, Operation, and Inspection Guidelines for
2、 Corrosion Control in Hydroprocessing Reactor Effluent Air Cooler (REAC) SystemsDownstream SegmentAPI RECOMMENDED PRACTICE 932-BSECOND EDITION, MARCH 2012ERRATA, JANUARY 2014Special NotesAPI publications necessarily address problems of a general nature. With respect to particular circumstances, loca
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17、be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually by API, 1220 L Street, NW, Washington, DC 20005.Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, W
18、ashington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Normative References. . . . . . . . . . . . . . . . . . . . . . . . . .
19、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.1 Codes and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Other References. . . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Terms, Definitions, and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.1 Terms and Definitions. . .
21、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.2 Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . 54 Background of REAC Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.1 History of Reactor Effluent System Corrosion Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54.2
23、 Typical Hydroprocessing Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.3 Effluent Separation Designs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . 84.4 REAC System Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Strategies to Promote System Reliability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25、 . . . . . . . . . 115.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.2 Material Selection and Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26、 . . . . . . . . . . . . . . . . . . . . . . . . . 125.3 Establishing an Operating Envelope (Integrity Operating Window) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125.4 Inspection Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27、 . . . . . . . . . . . . . . . . . . . . . . . 136 Process Variables Affecting Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.1 Ammonium Bisulfide Concentration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、 . . . . . . . . . . . . . . . . . . . . . . 136.2 Process Conditions at the Water Dew Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136.3 Fluid Velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146.4 Hydrogen Sulfide (H2S) Partial Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156.5 Flow Regime. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166.6 Chlorides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166.7 Other Process Variables . . . . . . . . .
31、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176.8 Wash Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176.9 Corrosion Inh
32、ibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206.10 Air Cooler Fan Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33、 . . 206.11 Process Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 Materials of Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34、 . . . . . . . . . . . . . . 217.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217.2 Material Selection Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 Equipment Specific Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258.1 Fin Fan Air Coolers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258.2 Shell-and-Tube Trim Coolers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278.3 Cold High-Pressure Separator (CHPS) . . . . . . . . . . . . .
37、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278.4 Heat Exchanger or Air Cooler Upstream of REAC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288.5 Piping methods to assess and monitor the corrosivity of systems; detai
38、ls on materials selection, design and fabrication of equipment for new and revamped processes; considerations in equipment repairs; and details of an inspection plan. Table 1 lists key issues to REAC system performance and section reference for more detail. Materials and corrosion specialists should
39、 be consulted for additional unit-specific interpretation and application of this document. This is especially important since new proprietary research is underway which challenges several previously held beliefs about NH4HS corrosion in the reactor effluent system. Each facility needs to establish
40、its own safe operating envelope to assure satisfactory service. This RP helps to identify key variables necessary for monitoring and establishing the operating envelope.Other equipment downstream of the REAC can also deteriorate from these ammonium salts. These include the recycle gas, sour gas and
41、the H2S stripper and product fractionator overhead systems. Although these are beyond the scope of this document, plant personnel should be alert to these other locations where ammonium salt fouling and corrosion can occur. Since the first edition of API 932-B was published in July 2004, findings fr
42、om a recent joint industry sponsored research program contributed important new data on NH4HS corrosion relevant to these systems. While not all the data are in the public domain, recent publications have highlighted key data which are incorporated into this current edition of API 932-B. 2 API RECOM
43、MENDED PRACTICE 932-B2 Normative References2.1 Codes and StandardsThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amen
44、dments) applies.API 510, Pressure Vessel Inspection Code: Maintenance, Inspection, Rating, Repair, and AlterationAPI 570, Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-service Piping SystemsAPI Standard 661, Air-cooled Heat Exchangers for General Refinery ServiceTable 1K
45、eys to REAC SystemsKey Issues SectionNH4HS Concentration Below 2 %, solutions are not highly corrosive to carbon steel. Above 2 %, solutions are increasingly corrosive. Materials of construction, piping configuration, and fluid velocity become important to corrosion.6.1Chlorides in Process Stream De
46、position and severe corrosion could result from NH4Cl. Inject water to remove salts and scrub process gas.6.6H2S Partial Pressure Higher H2S partial pressure increases corrosion rate for a given NH4HS concentration.6.4Wash Water Quantity of water injected to reduce NH4HS concentration and to allow s
47、ufficient free water at injection point. 6.8.2Quality of wash water critical to prevent increased corrosion and deposition of inorganic materials. 6.8.1Adequate distribution through single or multiple injection points with quills to assure REAC surfaces are washed.8.5.3.2Bulk Fluid Velocity Increasi
48、ng fluid velocity increases the corrosivity of the process. Velocities should be appropriate for the NH4HS concentration and material of construction.6.3Materials of ConstructionCarbon steel performs acceptably under low NH4HS concentration and velocities. Alloy 825 and duplex stainless steel are ap
49、propriate for more severe conditions. 7REAC Header Box and TubesHeader box design should promote good flow distribution through tube rows. 8.1.2.1U-tubes should be avoided. 8.1.2.2REAC Inlet and Outlet Piping DesignPiping design should minimize turbulence for NH4HS solutions. 8.5.2Piping configuration should promote balanced flow through all REAC inlets to prevent salt deposition and to distribute wash water. 8.5.3.1Process Variables and MonitoringEstablish an operating envelope and monitor key process variables to assure they remain within acceptable ranges.5.36.10Inspection Plan
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