We discussed the energy efficiency and other opportunities with fired heaters in past posts. I caught wind of a presentation that Emerson’s safety specialist, Chuck Miller will be giving at the upcoming March 21-25 AIChE Spring National Meeting and Global Congress on Process Safety in San Antonio, Texas. You may recall Chuck from numerous process safety-related posts.
He’ll be presenting, ICSS Systems Offer Advances in Fired Heater Operations, Safety, and Regulatory Compliance on Tuesday, March 23 at 9am. In his abstract, Chuck raises the questions:
Can the instrumentation, control, and protective systems for fired heaters as defined by the prescriptive API Recommended Practice 556 be reconciled with ANSI/ISA 84 (IEC 61511) by implementing an Integrated Control and Safety System? What cost savings can be identified and measured from both the CAPEX and OPEX viewpoint when applying advanced technology to adhere to these divergent standards?
If traditional approaches to compliance with process safety standards are driving costs up and yielding diminishing returns, which control architecture can provide cost savings while enabling the unit to be started-up, operated, and shut down safely?
Knowing that this conference is still a ways away, I asked Chuck if he had a “beta” version of his paper that he could share with me. Being the true professional and nice guy that he is, he forwarded me a copy of his work-in-process.
Process manufacturers have a common need to improve both safe operations and uptime through the avoidance of spurious trips in fired heaters and other fired units. Chuck notes that the professional associations have collaborated and developed a number of good engineering practices related to industrial flame management systems, such as NFPA 85, NFPA 86, API RP 556, ASME CSD-1, FM 7605, and API RP 14C. Each was developed from different perspectives from prescriptive design, to expected performance, to a practical experience viewpoint.
A prescriptive approach describes what process manufacturers should and should not do. A performance-based approach like the IEC 61511 global safety standard provides descriptions of methods without prescribing specific methods or suggestions to enact.
Chuck highlights the similarities and differences with respect to API Recommended Practice 556 (API RP 556), ANSI/ISA 84, and ISA-TR84.00.05 (ISA TR-5, Guidance on the Identification of Safety Instrumented Functions in Burner Management Systems). API RP 556 can be seen as prescriptive because it offers practical suggestions where S84/IEC 61511 does not offer specific recommendations.
He believes that API 556 will provide an excellent design specification for the process heater, primary measuring and actuating instruments, controls, alarms, and the associated protective systems. It is also sufficient to provide a starting point for an industrial flame management risk evaluation process and the basis for a Safety Requirements Specification (SRS).
API RP 556 also contains many references to requirements of ANSI/ISA 84 such as HAZOP requirements, nuisance trip avoidance, diagnostics & on-line testing, separation of control and safety functions, etc.
ISA TR-5 is currently in the process of development to provide guidance on how to Identify and classify safety instrumented functions (SIFs) within typical Burner Management System (BMS) for all operating modes of fired equipment including pre-firing, light-off, shutdown, and normal operation. Like API RP 556, the technical report states that due to the unique design criteria of every furnace, each heater/boiler will require that a HAZOP and layer of protection analysis (LOPA) be performed.
Chuck offers other similarities and differences as process safety professionals pick their way through the standards to manage the safety lifecycle of their operations. If you are involved in process safety and plan to attend the AIChE Spring meeting, you may want to include Chuck’s presentation on your agenda.