1、 Standard Practice Refinery Injection and Process Mix Points This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptance does not in any respect preclude anyone, whether he or she has adopted the stand
2、ard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE standard is to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any
3、 method, apparatus, or product covered by letters patent, or as indemnifying or protecting anyone against liability for infringement of letters patent. This standard represents minimum requirements and should in no way be interpreted as a restriction on the use of better procedures or materials. Nei
4、ther is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE assumes no responsibility for the interpretation or use of this standard by other parties and accepts responsibility for on
5、ly those official NACE interpretations issued by NACE in accordance with its governing procedures and policies which preclude the issuance of interpretations by individual volunteers. Users of this NACE standard are responsible for reviewing appropriate health, safety, environmental, and regulatory
6、documents and for determining their applicability in relation to this standard prior to its use. This NACE standard may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to
7、 within this standard. Users of this NACE standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirement
8、s prior to the use of this standard. CAUTIONARY NOTICE: NACE standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE requires that action be taken to reaffirm, revise, or withdraw this standard no later than f
9、ive years from the date of initial publication and subsequently from the date of each reaffirmation or revision. The user is cautioned to obtain the latest edition. Purchasers of NACE standards may receive current information on all standards and other NACE publications by contacting the NACE FirstS
10、ervice Department, 15835 Park Ten Place, Houston, TX 77084-5145 (telephone +1 281-228-6200). Approved 2014-06-26 NACE International 15835 Park Ten Place Houston, Texas 77084-5145 +1 281-228-6200 ISBN 1-57590-284-2 2014, NACE International NACE SP0114-2014 Item No. 21175 SP0114-2014 NACE Internationa
11、l i _ Foreword Corrosion at locations where two streams mix has caused significant failures in the petroleum refining industry over the years. This NACE standard addresses the unique nature of injection points and process mix points, in both design and inspection. This standard discusses typical mat
12、erial selection, corrosion concerns, and successful design and inspection practices used in petroleum refinery injection point and process mix point systems. This standard was originally prepared as a technical committee report in 2001 by NACE Task Group (TG) T-8-21, “Refinery Additives Injection Fa
13、cilities,” administered by Group Committee T-8, “Petroleum Refining and Gas Processing.” In 2014, TG 174 (formerly T-8-21) prepared this standard to replace the previous technical committee report NACE Publication 34101. TG 174 is administered by Specific Technology Group (STG) 34 (formerly Group Co
14、mmittee T-8), “Petroleum Refining and Gas Processing.” This standard is issued by NACE under the auspices of STG 34. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must ar
15、e used to state a requirement, and are considered mandatory. The term should is used to state something good and is recommended, but is not considered mandatory. The term may is used to state something considered optional. _ SP0114-2014 ii NACE International _ NACE International Standard Practice Re
16、finery Injection and Process Mix Points Contents 1. General 1 2. Definitions 1 3. Design Guidelines 2 4. Implications of Injection and Process Mix Points 6 5. Hardware Design . 6 6. Injection and Mix Point Location 10 7. Guidelines for Typical Refinery System . 11 8. Performance Verification and Mon
17、itoring 14 9. Inspection of Equipment 15 References 16 Appendix A: Variables Affecting Mixing/Dispersion (Nonmandatory) . 17 Appendix B: Case Histories (Nonmandatory) . 21 Appendix C: Sample Injection Point Data Sheet (Nonmandatory) . 27 Appendix D: Hardware Design Philosophy (Nonmandatory) 28 Appen
18、dix E: Considerations for Typical Refinery System Injection Designs (Nonmandatory) 32 FIGURES Figure 1: Configurations of Injection Devices . 9 Figure 2: Injection Device and Nozzle Orientations 9 Figure 3: Injection Nozzle Discharge Orientations 9 Figure A1: Flow Regimes in Horizontal Piping . 18 F
19、igure A2: Vertical Up-Flow Regimes . 18 Figure A3: Baker Plot Prediction of Flow Regimes for Horizontal Two-Phase Flow 19 Figure A4: Hewitt and Roberts Two-Phase Up-Flow in Gas-Liquid Flow Streams in Vertical Piping. Regime Map . 20 Figure A5: Change in Flow Regime as a Function of Inclination 20 Fi
20、gure B1: Hydrodesulfurizing Unit Separator Overhead Piping Isometric . 21 Figure B2: Atmospheric Cruide Column Overhead Piping Isometric 22 Figure B3: Light Ends Recovery Piping Isometric 23 Figure B4: Location of Crack in Process Mix Point at Heat Exchanger Bypass . 23 Figure B5a: Isometric of De-E
21、thanizer Line at Pipe Failure Location . 24 Figure B5b: Failure Downstream from Intermittent Injection Point . 25 Figure B5c: Failure at Extrados from Downstream Elbow 25 Figure D1: Chemical Dosing Alternatives . 29 Figure D2: Retractable Quill Assembly . 29 Figure D3: Hollow-Cone and Full-Cone Spra
22、y Distribution 30 Figure D4: Radial Sparger 31 TABLE Table E1: Guidelines for Wash Water Quality 36 _ SP0114-2014 NACE International 1 _ Section 1: General Injection points and process mix points for several typical refinery process streams are addressed in detail. The discussion of process mix poin
23、ts is limited to primary process streams, and considers only changes in temperature, pH, phase changes, and the concentration of corrosive species. Additional information is included in the Appendixes A through E (Nonmandatory). _ Section 2: Definitions Caustic Compounds or Caustic caustic, or caust
24、ic soda, or more formally, sodium hydroxide is a strong ionic chemical base. Other bases, such as potassium hydroxide, also fall into the category of caustic compounds. Carrier or Diluent a nonreactive stream that is combined with an injected chemical (e.g., amine neutralizer) to increase the volume
25、 flow through an injection device, improving control, distribution, mixing, and/or reducing injection device fouling. Drop Size Distribution the size distribution of drops, typically expressed by the size vs. cumulative volume (in percent). Chemical Injectant process additive or other process stream
26、 that is added to a process stream in small quantities, for control of corrosion, fouling, pH, or other chemical property of a process stream. Wash water is also a chemical injectant, but is typically added in larger quantities than other process additives. Injection Point locations where chemicals,
27、 or process additives, are introduced into a process stream. Corrosion inhibitors, neutralizers, process antifoulants, desalter demulsifiers, hydrogen, oxygen scavengers, caustic, and water washes are most often recognized as requiring special attention during injection point design. Mix Points mix
28、points are points of joining of process streams of differing composition and/or temperature where additional design attention, operating limits, and/or process monitoring are utilized to avoid damage mechanisms (e.g., corrosion). See also definition for Process Mix Point. Mixing Quill/Quill hardware
29、, including piping that intrudes into the main process stream, designed to optimize distribution of the injectant into the process stream. The quill itself is a thin hollow probe designed to deliver an injectant into a pressurized receiving stream, promoting improved dispersion/absorption of the inj
30、ectant into the receiving stream. Process Mix Point the locations where two process streams of differing chemical or physical (e.g., temperature, pressure, and phase) properties join at a piping tie-in. Reynolds Numbers (Re)dimensionless parameter used to characterize flow regimes, such as laminar f
31、low, which occurs at low Re numbers where viscous forces are dominant, or turbulent flow, which occurs at high Re numbers where inertial forces are dominant. Software programs are available that facilitate calculating Re. Shock Condensation condensation of liquid phase out of a vapor stream as the r
32、esult of mixing a lower-temperature stream with a higher-temperature vapor stream. When the resultant local temperature drops below the water or acid gas dew point of the combined stream, condensation may occur, which may result in localized or general metal loss. Spargera perforated pipe designed t
33、o promote even distribution of gas in a liquid stream. Spray Nozzle a precision device that facilitates dispersion of liquid into a spray. Nozzles are used for three purposes: increase liquid surface area to enhance evaporation/dispersion/mass transfer; to distribute a liquid over a cross-sectional
34、area; and/or to wet pipe walls downstream from the injection point. Thermal Fatiguea cracking mechanism caused by repeated thermal cycling. Water Wash Injection injection of water into process streams on a continuous or intermittent basis to: introduce water upstream from the salt deposition tempera
35、ture, remove salt deposits that foul and/or can cause corrosion, or dilute a condensing stream to make it less corrosive. SP0114-2014 2 NACE International _ Section 3: Design Guidelines 3.1 Process ConsiderationsInjection and process mix points are process tie-ins. They differ from other process tie
36、-ins because they have the potential to compromise mechanical integrity. They typically meet one or more of the following criteria: (a) Mix two distinctly separate streams; (b) Promote chemical or physical reactions when mixing the constituents of two or more process streams; (c) Scrub or extract co
37、nstituents of one stream by contact with another stream; (d) Heat or cool one process stream by direct contact with another stream (including flashing or quenching); (e) Adding chemical additives to a process stream to adjust pH or improve on process operations; or (f) Wetting internal surfaces of p
38、rocess equipment to inhibit corrosion. 3.1.1 During initial process design, injection points and process mix point systems (including fabrication details) shall be reviewed in detail. A thorough safety review (e.g., hazard and operability HAZOP) should be conducted. A data sheet should be generated
39、for all injection points. A sample is provided in Appendix C. The owner shall ensure that injection system equipment is adequate and meets plant standards. It is also the owners responsibility to ensure that mechanical integrity of the equipment be maintained. 3.1.2 Engineering design guidelines sha
40、ll be based on successful industry and user experiences. Computational fluid dynamic (CFD) simulations of injection or process mix points may be used to improve understanding of the designs impact on system integrity. 3.1.3 Process simulation of refinery operating environments may be necessary to de
41、termine the impact of the mixing of the streams on variables important to the corrosiveness of the stream (e.g., mass flow, temperature, pressure drop, nozzle positioning and orientation, fluid type, and fluid density). 3.2 Continuous vs. Intermittent Water Wash Injection 3.2.1 When corrosion contro
42、l is the primary consideration, continuous water injection shall be used. Continuous water wash in overhead lines has the advantage of requiring less operator interaction, continuously washing away corrosive agents, and avoiding wet/dry cycling in high corrosion potential zones. The disadvantage is
43、that although water was injected to reduce the concentration of corrosive species, the system is now continuously wet, allowing corrosion, albeit at lower rates, to be continuous. 3.2.2 If fouling control is the only objective, wash water availability is limited, and where there is little risk of co
44、rrosion, intermittent injection rather than continuous injection may be sufficient. When process system pressure drop limitations exist, intermittent wash water injection may be used. The use of intermittent injections, though, must consider the potential impact of increased corrosion during the cyc
45、le of injection and for the potential build-up of corrosive salts and subsequent under-deposit corrosion. 3.2.3 When water is injected into a vapor stream, designs should ensure that sufficient liquid water remains after flashing to dilute corrosive species to a manageable level at the process maxim
46、um operating temperature. Typical targets are 25% of the injected water remaining liquid after the injection point. 3.3 Carrier or Diluent Fluids 3.3.1 If limiting the injectant chemical concentration is critical, or if increasing total volumetric flow of the injectant stream is required to obtain g
47、ood dispersion, then a carrier (diluent) fluid shall be used. 3.3.2 Carrier fluids should be nonreactive and maintain sufficient phase stability within the injection device. Light gas oil, heavy naphtha, water, and steam have been used successfully for various applications. Reflux slip-streams often
48、 are used as carrier fluids for injection into overhead systems. SP0114-2014 NACE International 3 3.3.3 Controlled carrier fluid flow rates should be maintained to promote dispersion, to improve injection concentration control in the receiving stream, and to prevent problems such as excessive quenching, which can be caused by excessive carrier fluid flow. One method of doing this is to use a carrier pump that restricts the flow rate to within the control band of t
