High-temperature fireside corrosion monitoring in the superheater section of a pulverized-coal-fired boiler
- Capcis-March Ltd., Manchester (United Kingdom)
The work described in this report was the first British in-plant application of continuous online electrochemical corrosion monitoring technology in pulverized coal-fired superheater environments. The work was conducted at Drax Power Station, National Power plc, UK. The investigation was to evaluate the relative corrosion performance of stainless steel Alloys 316 and 310. Two electrochemical sensor assemblies fabricated from the test alloys were attached to the end of a coupon exposure probe which was inserted into the superheater section of a 660MW boiler. The probe assemblies were exposed at a nominal temperature of 665[degrees]C (1229[degrees]F) during the trial. two series of short term temperature scanning tests were carried out. Alloy 310 performed comparatively better than Alloy 316. Minimal corrosion loss was sustained by Alloy 310 whilst a characteristic wastage flat was observed on Alloy 316. It was shown that variations in boiler operation could affect the minute-to-minute corrosion behavior of the test materials. The results of the brief temperature scan program indicated a trend of increasing corrosion with exposure temperature. No evidence was observed of the bell-shaped'' curve behavior reported in laboratory studies of molten salt corrosion. Metallographic examination of the sensors indicated that only small and discrete areas of internal sulfur enrichment beneath the surface scale. This is untypical of the morphology of sulfur enriched scale found in molten salt corrosion systems. The corrosion processes were predominately in the form of oxidation/sulfidation. The formation of a wastage flat was postulated to have been caused by an electrochemical mechanism similar to that of flow assisted corrosion in aqueous electrolytes. These results confirmed that continuous on-line electrochemical instrumentation could be used to investigate, monitor and characterize high temperature oxidation in power generation boiler superheaters.
- Research Organization:
- Electric Power Research Inst., Palo Alto, CA (United States); Capcis-March Ltd., Manchester (United Kingdom)
- Sponsoring Organization:
- EPRI; Electric Power Research Inst., Palo Alto, CA (United States)
- OSTI ID:
- 6845888
- Report Number(s):
- EPRI-TR-101799
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
36 MATERIALS SCIENCE
47 OTHER INSTRUMENTATION
ELECTROCHEMICAL CORROSION
MONITORING
STAINLESS STEELS
SUPERHEATERS
ALKALI METAL COMPOUNDS
BOILERS
CHLORINE
COAL
FOSSIL-FUEL POWER PLANTS
OXIDATION
STAINLESS STEEL-310
STAINLESS STEEL-316
SULFATES
SULFIDATION
ALLOYS
AUSTENITIC STEELS
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM-NICKEL STEELS
CHROMIUM-NICKEL-MOLYBDENUM STEELS
CORROSION
CORROSION RESISTANT ALLOYS
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
HALOGENS
HEAT RESIS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NONMETALS
OXYGEN COMPOUNDS
POWER PLANTS
STEEL-CR17NI12MO3
STEEL-CR25NI20
STEELS
SULFUR COMPOUNDS
THERMAL POWER PLANTS
200104* - Fossil-Fueled Power Plants- Components
014000 - Coal
Lignite
& Peat- Combustion
360105 - Metals & Alloys- Corrosion & Erosion
440800 - Miscellaneous Instrumentation- (1990-)