SpectralEmissivity & Emittance

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Furnace radiation modelling

Furnace radiation modeling

Location: Industrial Research Limited (IRL): Measurement Standards Laboratory of New Zealand
Their Client: New Zealand Refining Company
The Topic: Infrared radiation thermometry for furnace tube temperature measurement
Client benefit: High quality measurement leads to better plant control, reduced risk and increased profitability

Most of this article is from the writeup on the IRL website.

Industrial Research undertook furnace radiation modeling for the New Zealand Refining Company which operates several large furnaces in many stages of the production of gasoline (Also known around the world variously as “petrol” and “benzene”).

Thermal infrared radiation thermometry, or IR Thermometry, is the only feasible method for obtaining temperature measurements of many furnaces and the process tubes within.

The technology is not new, it was known that the measurements suffer from errors stemming from several environmental factors such as reflection of background thermal radiation and absorption and emission of the emitted & reflected radiation (from the surfaces being measured, by furnace gases.

Variations in the spectral emissivity and reflectivity of the materials comprising the surfaces being measured also influence the resulting temperature measurements.

The New Zealand Refining Company used the knowledge and background offered by Industrial Research’s Measurement Standards Laboratory in furnace radiation modelling to obtain more accurate measurements.

The service gave increased confidence that safe and efficient operating parameters were being maintained. As a result, the plant can operate more efficiently through the operators being able to better predict plant life and tube life.

New System for Spectral Emissivity Measurements & Spectral Emissivity of Metals at the University of Duisburg

On the 13-15 June, 2001, in Budapest, Hungary, the 12th International Conference on Thermal Measurements and Thermogrammery (THERMO) was held.

Among the papers were two by Prof. Dr.-Ing. W. Bauer, Dipl.-Phys., A. Moldenhauer, Dipl.-Phys. & M. Rink of the Gerhard Mercator Universität Duisburg, Germany

The first presentation was entitled:

“New System for Spectral Emissivity Measurements at the University of Duisburg”

(Click on the link to access the Abstract in PDF Format)

The second was:

“Spectral emissivities of metals dependent on heat-treating processes”.

(Click on the link to access the Abstract in PDF Format)

Other papers by the members of the Duisburg Universitat have their abstracts listed on this Conference information page, also.

Contacts for more information are:

Prof. Dr. Ing. W. Bauer, Gerhard-Mercator-Universität, Duisburg, Germany

Fachbereich 8, Fachgebiet Energieeinsatz(Germany)
47048 Duisburg
Tel.: +49 203/379-3629
Fax.: +49 203/379-3464

Prof. Dr. Ing. W. Bauer

Email: bauer [at] ihg.uni-duisburg.de

and

Thomas Funke Dipl.-Ing.


Email: Thomas.Funke [at] uni-duisburg.de

Homepage: www.ihg.uni-duisburg.de/energieeinsatz/

Normal Spectral Emittance of Some Metals, Carbon and SiC

The “Emissivity” page on the FAR Associates website includes a discussion of their unique instrument along with graphs and some tables of spectral emissivity values are evidently all reproduced from the Thermophysical Properties of Matter, Vol. 7: Thermal Radiative Properties, Y.S. Touloukian and D.P. DeWitt, IFI/Plenum, New York, 1970.

These include curves for: Carbon (Graphite), Tungsten, Aluminum, Copper, Iridium, Iron, Molybdenum, Silicon Carbide, Stainless Steel and Titanium.

Raytek’s Spectral Emissivity Table for Non-metals

The Raytek North America website includes a table for the emissivity of a large range of non-metallic materials that includes common building materials, ceramics, glasses and natural materials including ice & water in as many as four wavelength regions.

Wavebands covered include 1.0 micrometer (micron), 5.0 microns, 7.9 microns and the 8-14 micron band. No specific data and the limits of the various wavebands and there are many instances where the wavelength region is labelled as “nr” meaning “Not Recommended”.

Land Instruments Infrared Theory Notes

Infrared Theory Notes-(Last updated 04/11/04, PDF Download of 547kb – 43 pages) contains not only some simple explanations of the key features of Radiation Thermometry, how it works and how IR Thermometers work in various measurement situations, but also provides some unique graphical representations of the transmission of glasses (see pages 30-33).

It also discusses thin plastics. In the latter case, see pages 34-36 for unique emissivity data and curves versus material type and thickness at 3.43 micrometers (microns) and explanations of an alternate choice waveband region at 7.9 microns.