Tubing wastage in fluidized-bed coal combustors: Test Series 2 NCB (IEA Grimethorpe) Ltd

Technical Report · Fri Jan 08 04:00:00 EST 1988

OSTI ID:5077168

Witherell, C E; Meisenheimer, R G

This study of wasted heat-exchanger tubing from the Grimethorpe PFBC Facility was conducted to characterize affected fireside surfaces and identify the mechanism/s responsible. Examinations showed that the wasted surfaces are not typical of those produced by erosion alone, as oxide deposits are present on all surfaces. Continual exfoliation of the normally-protective oxide layer is probably responsible for a major portion of tubing wastage. There are also indications of direct metal loss occurring through a series of events wherein repeated formation and exfoliation of surface oxides produce an irregular metal interface that is mechanically deformed during combustor operation. Cold-worked metal protrusions, or platelets, on the roughened surface readily fracture from the tubing wall and are lost into the bed. In some combustors where metal temperatures generally are above 600 C (1100 F), sulfidation-oxidation corrosion has been identified as the mechanism responsible for metal loss. These occurrences have largely been confined to air heater tubes, uncooled support members, and the like. However, the more perplexing type of metal wastage in FBCs/endash/and that which is the subject of this study/endash/has occurred at much lower metal temperatures of about 400 C (750 F) in in-bed water-cooled tubes. There have been differences of opinion over its cause but the consensus is that erosion is a major factor, if not the sole cause. Examinations have shown that wasted surfaces of heat exchanger tubing from this combustor are the product of combined mechanical, chemical, and thermal effects, all interrelated to produce rapid and localized metal loss. 33 refs., 29 figs., 3 tabs.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5077168
• Report Number(s): UCRL-21039; ON: DE88009810
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
014000* -- Coal
Lignite
& Peat-- Combustion
42 ENGINEERING
421000 -- Engineering-- Combustion Systems
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
COMBUSTION
COMBUSTORS
CORROSION
ENERGY SOURCES
EROSION
FLUIDIZED-BED COMBUSTION
FLUIDIZED-BED COMBUSTORS
FOSSIL FUELS
FUELS
MATERIALS
MATERIALS TESTING
OXIDATION
SULFIDATION
TESTING
THERMOCHEMICAL PROCESSES
TUBES