1、Instrumentation, Control, and Protective Systems for Gas Fired HeatersAPI RECOMMENDED PRACTICE 556 SECOND EDITION, APRIL 2011Instrumentation, Control, and Protective Systems for Gas Fired HeatersDownstream SegmentAPI RECOMMENDED PRACTICE 556 SECOND EDITION, APRIL 2011Special NotesAPI publications ne
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13、ector.Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog
14、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, Washington, DC 20005, standardsapi.org.iiiContentsPage1 Scope . . . . . . . . . . . . .
15、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16、 . . . . . . 11.2 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.1 Normative References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Other References. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Fired Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.1 General . . . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Process Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.3 Pr
20、ocess Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.4 Protective Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、. . . . . . . . . . . . 21Figures1 Forced Draft Fired HeaterFuel Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Natural Draft Fired HeaterFuel Side. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . . . . . . . . . . . . . . 233 Natural Draft Fired HeaterProcess Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Tables1 Alarm Summary Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、 . . . . . . . . . . . . . . . . . . . 552 Safe State Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563 Cause and Effects Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 614 Startup Sequence, Natural Draft Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625 Startup Sequence, Forced Draft and Balanced Draft Heaters . . . . . . . . . . . .
25、. . . . . . . . . . . . . . . . . . . . . . . 64Annex A (normative) Tube Rupture Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66v1Instrumentation, Control, and Protective Systems for Gas Fired Heaters1 Scope1.1 Purpose1.1.1 This recom
26、mended practice (RP) provides guidelines that specifically apply to instrument, control and protective system installations for gas fired heaters in petroleum production, refineries, petrochemical and chemical plants. 1.1.2 A gas fired general service heater defined in this practice liberates heat b
27、y the combustion of fuel gas and this heat is transferred to liquids and/or gases in tubular coils all contained within an internally insulated enclosure. 1.1.3 Not covered in this RP are the following: oil fired and combination fired heaters; water tube boilers which consist of single or multiple b
28、urners and are designed for utility operation or where the primary purpose is steam generation (covered by NFPA 85); fired steam generators used to recover heat from combustion turbines i.e. heat recovery steam generators (HSRG); oven and furnaces used for the primary purpose of incineration, oxidat
29、ion, reduction or destruction of the process medium (covered by NFPA 86); water bath or oil bath indirect fired heaters (covered by API 12K); CO boilers, pyrolysis furnaces (e.g. ethylene and hydrogen reformers), and other specialty heaters.1.1.4 This RP includes primary measuring and actuating inst
30、ruments, controls, alarms, and protective systems as they apply to fired heaters. For additional subject matter review, refer to the referenced or industry standards.1.2 General1.2.1 Instrumentation and control applications incorporate systems and devices to satisfy equipment specific requirements.
31、Equipment specific requirements include safety, process control, data collection, environmental reporting and other local applications.1.2.2 Documentation including schedules, drawings, sketches, specifications and other data should be provided to install the equipment in the desired manner and for
32、the users to maintain, inspect, test and operate the system in a safe manner. 1.2.3 The various industry codes and standards as well as laws and rules of local regulating bodies shall be followed where applicable. 1.2.4 Although it is no substitute for experience and proficiency in these fields, thi
33、s document is intended to assist users with achieving such experience and proficiency. Because of the lack of uniformity in the design and requirements of the processes, the complete instrumentation and control system must be studied to determine if it will enable the unit to be started-up, operated
34、, and shut down satisfactorily and safely.2 API RECOMMENDED PRACTICE 5562 References2.1 Normative ReferencesThe 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 t
35、he referenced document (including any amendments) applies. API Specification 6FA, Specification for Fire Test for ValvesAPI Specification 12K, Indirect Type Oil-Field HeatersAPI Recommended Practice 534, Heat Recovery Steam GeneratorsAPI Recommended Practice 535, Burners for Fired Heaters in General
36、 Refinery ServicesAPI Recommended Practice 551, Process Measurement InstrumentationAPI Recommended Practice 553, Refinery Control ValvesAPI Recommended Practice 554, Process Control Systems, Part 1 through 3API Recommended Practice 555, Process AnalyzersAPI Standard 560/ISO 13705, Fired Heaters for
37、General Refinery ServicesAPI Recommended Practice 573, Inspection of Fired Boilers and HeatersAPI Standard 598, Valve Inspection and TestingAPI Standard 607, Fire Test for Quarter-turn Valves and Valves Equipped with Non-Metallic SeatsANSI/ISA 84.00.01-2004 (IEC 61511-Mod) 1, Functional Safety: Safe
38、ty Instrumented Systems for the Process Industry SectorNFPA 325 2, Guide to Fire Hazard Properties of Flammable Liquids, Gases, and Volatile Solids, 1994 edition.2.2 Other ReferencesCertain systems are not covered in this document because of their specialized nature and limited use in petroleum refi
39、nery, hydrocarbon-processing, petrochemical, and chemical plants. When one of these systems gains general usage and installation reaches a fair degree of standardization, this document will be revised to provide additional information. The following documents are not directly applicable to refinery
40、heaters. These are referenced as they may be cited by regulatory bodies.ANSI/FCI 70-2 3, Control Valve LeakageASME, CSD-1 4, Controls and Safety Devices for Automatically Fired Boilers1American National Standards Institute, 25 West 43rdStreet, 4thFloor, New York, New York 10036, www.ansi.org.2Nation
41、al Fire Protection Association, 1 Batterymarch Park, Quincy, Massachusetts 02169-7471, www.nfpa.org.3Fluid Components International, 1755 La Costa Meadows Drive, San Marcos, California, .INSTRUMENTATION, CONTROL, AND PROTECTIVE SYSTEMS FOR GAS FIRED HEATERS 3EN 746-2 5, Industrial thermo processing
42、equipment, Part 2, Safety requirements for combustion and fuel handling systems. ISA TR.84.00.05 6, The Application of ANSI/ISA 84.00.01-2004 (IEC 61511) for Safety Instrumented Functions (SIFs) in Burner Management SystemsNFPA 85, Boiler and Combustion Systems Hazards CodeNFPA 86, Standards for Ove
43、ns and Heaters3 Fired Heaters3.1 GeneralAPI 560 contains instrumentation requirements for fired heaters and their auxiliaries. 3.2 Process MeasurementInstallation of instrumentation should consider accessibility for efficient maintenance and for good operation. Flow elements, control valves, transmi
44、tters, thermowells, level gauges, and local controllers, as well as analyzer sample points, generally should be readily accessible from grade or from permanent platforms or fixed ladders. In this document, special consideration is given to the location, accessibility, and readability of the elements
45、. Refer to API 551 for installation details.3.2.1 TemperatureContinuous temperature measurement in fired heater applications generally uses thermocouples.3.2.1.1 Bridgewall TemperatureThe bridgewall temperature is the temperature of flue gas leaving the radiant section. Each heater and each cell of
46、a heater should have a bridgewall temperature thermocouple located at least two feet into the firebox and just upstream of the convection section. This temperature is used for trending the approximate flue gas temperature. Highly accurate temperature measurement here is not necessary for normal refi
47、nery service heaters. Long/large fireboxes may require several bridgewall temperature measurements along the length of the box. These measurements may be useful in assessing the uniformity of heat distribution along the length of the firebox. Thermocouples in the radiant section should be installed
48、with wells or other protective devices. The point of measurement should not have flame impingement. The thermocouples should extend past the shadow of the tube and be placed to avoid dead spots. A sample port next to the thermowell location is recommended to allow temperature verification. Thermowel
49、l materials must be suitable for the firebox temperatures and atmosphere. American Iron and Steel Institute (AISI) Types 446 and 347 stainless steel are generally acceptable materials. For some severe services, 310 stainless steel, nickel chromium iron alloy, ceramic, or ceramic-coated thermowells have been used. 4ASME International, 3 Park Avenue, New York, New York 10016-5990, www.asme.org.5European Committee for Standardization, Avenue Marnix 17, B-1000, Brussels, Belgium, www.cen.eu.6International Society of Automation, 67 Alexander Drive, Res
