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Over 35 Years of Providing Metallurgical Analysis

Coal Particle Erosion

External Appearance: 
Flat tubes adjacent to either cyclone or tangent fired boiler burners. 


Probable cause:
Coal particle erosion is caused when the wear protective devices inside the cyclone burner are no longer able to perform their function, or there is fuel bypassing the nozzle and abrading the adjacent offset tubes.
The root cause of coal particle erosion can be verified through observation of the condition of the wear resistant liners and refractory coatings that have been installed to protect the boiler tubing.  Observation of the flow patterns that are established in the burner from the introduction of secondary and tertiary air may reveal potential hotspots for coal particle erosion.   

Visual examinations and ultrasonic (UT) tube wall thickness measurements are used to detect and monitor coal particle erosion.  Small diameter UT transducers are used to obtain tube wall thickness measurements since access to the tube surface is limited by the cylindrical studs welded onto the tube.  UT measurements help determine the appropriate extent of immediate repairs after a failure and to plan for tubing replacement during a boiler overhaul outage.

Corrective action:
Corrective actions involve surveillance and replacement of the wear resistant liners and refractory coatings so that their protective function is not lost during boiler operation.  Adjustments of secondary and tertiary air may also be necessary. 

Comment:

Coal particle erosion occurs in cyclone type coal burners where the introduction of combustion air at high velocity, and tangent to the tube surface, imparts a whirling motion to the incoming coal. Coal particle erosion also occurs adjacent to tangent burner corners. 
Coal particle erosion produces thinning of the tube wall. A thin-edged fracture results when the wall thickness is reduced to a point beyond its ability to contain the internal water pressure.
Common Locations: Water walls

Locations


Email contact@davidnfrench.com or call 502-955-9847 to speak directly with a member of the DNFM team. 


2681 Coral Ridge Road
Brooks, KY 40109

Call Us: (502) 955-9847

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