Industrial Boiler Troubleshooting Discussion

Paper from the AFRC 2017 conference titled Industrial Boiler Troubleshooting Discussion

Industrial Boiler Troubleshooting Discussion AFRC -Houston, Tx, December 13, 2017 Paul Eichamer, Joseph Tleimat, Matt Whelan Industrial Boiler Troubleshooting ¡ ¡ ¡ ¡ Boilers are a critical component of U.S. commercial and industrial facilities and operations. There are approximately 43,000 industrial boilers in the United States. In October 2015, API published an Industrial Boiler Standard Practice (350 pages). This Standard Practice specifies requirements and gives recommendations for troubleshooting considerations, design, operation, maintenance for industrial fired boilers used in refineries and chemical plants. This Standard Practice covers air/fuel combustion control, burner management systems (BMSs), functional control diagrams, emissions, waterside control, feedwater preparation, startup procedures, etc. Industrial Boiler Troubleshooting ¡ ¡ This document reflects the accumulated knowledge and experience of manufacturers and users of industrial fired boilers. Over a six year period, 60 individuals participated often and another 70 individuals participated sometimes. This Standard Practice complements rather than duplicates requirements in other Industry Standards l l l National Fire Protection Association Codes focus on a boiler's burner management safety system. ASME Codes focus on a boiler's mechanical construction and performance testing. Boiler considerations for combustion control, waterside control, feedwater preparation, steam quality, emissions, and more are not covered by other standards-writing bodies. Industrial Boiler Troubleshooting ¡ Reliable boiler operation is the objective. ¡ Combustion, air/fuel combustion control, burner management systems, functional control diagrams, emissions, waterside control, feedwater preparation, startup procedures, etc. can affect that reliable operation, either separately or in combination. ¡ Troubleshooting must determine what are the primary, secondary, and possibly tertiary causes that may reduce reliable and acceptable boiler operation/performance. Industrial Boiler Troubleshooting evaluations should address ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ Burners Gas fuel composition Oil fuel properties Igniters Combustion controls Burner Management System Boiler Master/Steam Pressure Controls. Controls Critical boiler interlocks ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ Shutdown devices and alarms Bypasses Furnace (firebox) tubes Draft controls Water quality Superheater tubes Steam Generator tubes Economizer tubes Steam and Mud Drums Industrial Boiler Troubleshooting ¡ ¡ ¡ ¡ Let's discuss Paul Eichamer, Fired Equipment Specialist L.L.C. (ExxonMobil retiree) Joseph Tleimat, Valero Matt Whelan, Coen Industrial Boiler Troubleshooting System overview Industrial Boiler Troubleshooting Boiler burner Industrial Boiler Troubleshooting Burner flame - correctly centered CASE STUDY ON BOILER ACCIDENT CHIA BAK KHIANG ASST. EXECUTIVE ENGINEER OSD, MOM Industrial Boiler Troubleshooting Package boiler - D-type OVERVIEW OF UTILITY BOILER PHOTOGRAPHS OF BOILER AFTER EXPLOSION Industrial Boiler Troubleshooting Tube blisters - direct flame contact Industrial Boiler Troubleshooting Superheater tubes - deformed Industrial Boiler Troubleshooting Steam drum internals Industrial Boiler Troubleshooting Waterside issues - tube interiors Industrial Boiler Troubleshooting Industrial Boiler Troubleshooting Case Study Teaching an old Dog New Tricks ¡ AKA - Retrofitting an old boiler with Next Generation UltraLow NOx Burners is frequently easier said than done. ¡ Boiler Background - Originally on a WWII destroyer. Valero repurposed it for service in an oil refinery. l l l Balanced draft design, firebox normally operated with a slight vacuum 2 - 75 MMBtu/hr burners. Ambient combustion air ¡ Local regulatory agency required Valero to reduce NOx emissions to 0.03 lb/MMBtu ¡ Valero selected Next Generation burners with some steam injection assist. Industrial Boiler Troubleshooting ¡ ¡ ¡ ¡ Zeeco Free Jet UltraLow NOx burners were installed Boiler was put in service and could not meet capacity expectations without exceeding CO emission limits. Additional symptom - with the limited viewing available the flames looked soft and lazy. Hmmm……What to Do????? Industrial Boiler Troubleshooting ¡ Blame the Burner Manufacturer!!! (Great Idea) ¡ Zeeco was contacted, seeking help ¡ Zeeco blamed the boiler claiming it leaked like a sieve. ¡ Theory was that significant air was coming in via casing leaks instead of the burners. This lead to poor mixing and long flames. ¡ These issues were addressed. It took about 1 year ¡ This allowed a partial increase in capacity, but not much. Industrial Boiler Troubleshooting Industrial Boiler Troubleshooting Industrial Boiler Troubleshooting ¡ Hmm….What now? ¡ Team of Zeeco and Valero engineers began brainstorming ways to address symptoms - lazy flame and high CO. ¡ Observed fuel pressure to burners was lower than expected. l l l l Burners were designed for steam injection into the fuel to assist NOx reduction (0.3 lb steam per lb fuel). However, steam was not being used as NOx was below target without it. This reduced fuel tip pressure and therefore mixing. We tested adding back steam and discovered we could get a little higher capacity before CO emissions were a problem. Long term - changed to steam injection into air stream instead. This way fuel mixing energy not compromised. Fuel tips were replaced with ones designed for higher fuel pressure. Industrial Boiler Troubleshooting ¡ Reviewed burner design information: l l l l Noted the inquiry datasheets listed boiler firebox length as TBA. Noted proposal datasheets listed expected flame length was 26 feet. Remembered walking around boiler and it did seem that long. Reviewed boiler drawing and appreciated why this could be an issue. Next slide shows only drawing available. Industrial Boiler Troubleshooting l l l l We did a field walk, pulled out a tape measure and did lots of head scratching. We came to the conclusion the firebox was only 14' long. With this new information, it became clear what the problem was. An air swirler was added to the burner design. The swirler was installed at the next opportunity (it took a couple iterations). The boiler now fires desired capacity, making NOx and CO emissions. The swirler increased design air pressure drop from 3.25" wc to 3.5" wc. Industrial Boiler Troubleshooting