Research Papers

A Thermal Model for Concentric-Tube Overfire Air Ports

[+] Author and Article Information
Larry W. Swanson, David K. Moyeda

 GE Environmental Services, 1831 E. Carnegie Avenue, Santa Ana, CA 92705

J. Thermal Sci. Eng. Appl 1(1), 011004 (Jul 21, 2009) (5 pages) doi:10.1115/1.3159524 History: Received December 18, 2008; Revised March 09, 2009; Published July 21, 2009

A quasisteady multimode heat-transfer model for boiler concentric-tube overfire air ports has been developed that predicts the effect of geometry, furnace heat source and heat sink temperatures, axial injector wall conduction, and coolant flow rate on the tube wall temperature distributions. The model imposes a radiation boundary condition at the outlet tip of the ports, which acts as a heat source. The model was validated using field data and showed that both the airflow distribution in the ports and tube diameter can be used to control the maximum tube wall temperature. This helps avoid tube overheating and thermal degradation. For nominal operating conditions, highly nonlinear axial temperature distributions were observed in both tubes near the hot outlet end of the port.

Copyright © 2009 by American Society of Mechanical Engineers
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Figure 1

Concentric-tube OFA port geometry

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Figure 2

Concentric-tube differential model geometry

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Figure 3

Model comparison with 200 MW boiler field data

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Figure 4

Model comparison with 600 MW boiler field data

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Figure 5

Tube 1 wall temperatures (d2=0.6 m, L/d2=2.0, and total flow rate=0.50 kg/s)

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Figure 6

Tube 2 wall temperatures (d2=0.6 m, L/d2=2.0, and total flow rate=0.50 kg/s)



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