Sponsored by: LMD Aluminum Committee
Program Organizer: Lise Castonguay, Alcan International Ltd., Arvida Research and Development Centre, PO Box 1250, 1955 Mellon Blvd, Jonquière, Québec, Canada, G7S 4K8
Tuesday, AM Room: A7
February 6, 1996 Location: Anaheim Convention Center
Session Chairperson: Mr. William R. Roder, Reilly Industries, Inc., 1500 South Tibbs Avenue, PO Box 42912, Indianapolis, IN 46242-0912
LABORATORY PITCH PAH AND POM STUDY: E. R. McHenry, W. E. Saver, Koppers Industries, Inc., 1005 William Pitt Way, Pittsburgh, PA 15238
The polynuclear aromatic hydrocarbon (PAH) measurements for a series of pitches are reported as a function of feedstocks and product softening point. The relationship of PAH to the polycyclic organic matter (POM) which evolves during the pitch carbonization (baking) cycle, is also studied. By combining selected feedstocks and processes, a reduction in toxic PAH and POM content in pitches can be achieved.
EVAPORATION AND VAPOUR CHARACTERISATION OF LOW-PAH BINDERS FOR SODERBERG CELLS: Mari Eie, Harald A. Oye, Institute of Inorganic Chemistry, The Norwegian Institute of Technology, University of Trondheim, N-7034 Trondheim, Norway; Morten Sorlie, Elkem a/s Research, PO Box 40 Vagsbygd, N-4602 Kristiansand, Norway
Polyaromatic hydrocarbon (PAH) vapour emissions from coal-tar pitches used as binders in the anode paste production can be an environmental concern for aluminium smelters. Pitch producers have responded to this by offering PAH-reduced anode binders, but with quite variable PAH distributions. Some producers have reduced both light and heavy PAH compounds while others have reduced the content of heavy PAH but reintroduced some light PAH compounds by using PAH-containing cut-back oils. As each country has different regulations and legislation, similar PAH emission profiles may be classified as satisfactory in one country and unacceptable in another. The paper gives emission characterisations of such PAH-reduced pitches.
SHOT COKE: P. J. Ellis, Great Lakes Carbon Corporation, PO Box <<C>>, Port Arthur, TX 77640; J. D. Bacha, Chevron Research and Technology Company, 100 Chevron Way, Richmond, CA 94802-0627
Shot coke is not desired in aluminum anodes, but 55% of all delayed coke in USA contains shot coke. Shot coke formation is due to refinery crude oil economics and improved operations which increased the asphaltene content in the coker feedstock. Diagrams showing how shot coke forms in the coke drum, along with a review of current technology on shot coke will be covered.
A STUDY ON COKE DUST GENERATION IN A ROTARY CALCINATION KILN: Y. S. Kocaefe, F. Dahmane, R. T. Bui, Process and Systems Engineering Research Group (GRIPS), Department of Applied Sciences, University of Québec at Chicoutimi, 555, boul. de l'Université, Chicoutimi, Québec, Canada, G7H 2B1; André L.Proulx, Alcan International Ltd., 1955 Mellon Blvd, PO Box 1250, Jonquière, Québec, Canada G7S 4K8
One of the steps in the production of carbon electrodes is the green coke calcination. This allows the removal of moisture and volatile matter, and also the restructuring of the coke. Coke dust is a by-product of this process and has an important impact on the process. It causes environmental problems and loss of production. Also, it affects the process through its combustion and its participation in the heat transfer. A study has been carried out to investigate (both experimentally and through mathematical modelling) this dusting phenomenon. This paper will present the results of the experimental study which show the influence of various parameters on the coke dust generation.
10:00 am BREAK
MATHEMATICAL MODELLING OF A ROTARY HEARTH CALCINER: R. Fernandez, STATOIL Technical Service Centre, PO Box 3, N-5154 Mongstad, Norway; H. C. Meisingset, and J. G. Balchen, The Norwegian Institute of Technology - NTH, Department of Engineering Cybernetics, N-7034 Trondheim, Norway
Calcination of petroleum coke is a thermal process where green petroleum coke is heat-treated to a pre-determined temperature. During heat treatment, the associated moisture is removed and volatile combustile material (VCM) released. This is burned in the gas phase giving the energy to sustain the process. In addition, structural changes take place. The combination of the final calcination temperature and the residence time determine the final density of the calcined coke. Depending on its further use, different real density requirements may arise. It is important to control the dynamics of the calcination process so that the specified final quality is achieved. A dynamic mathematical model of a Rotary Hearth Calciner is presented. The model is based on physicochemical laws involving the most important phenomena taking place and the relevant calcination parameters. The temperature profile in the coke bed is predicted which in terms is related to the real density of the coke.
STEPS FOR GREEN COKE CALCINATION - MATHEMATICAL MODEL AND PRACTICAL TESTS AND EXPERIENCES: Dr H. Predel, ESSO AG, Karlsruhe Refinery, ESSO-Str. 1, 76187 Karlsruhe, Germany
The different steps for green coke calcination like: water evaporation,
drying, VCM evaporation, VCM burning, heating-up ramps, soaking period are
calculated with a mathematical model. The results are compared with practical
experiences for regular calcined coke production and with sampling programs
during calcination process. The results are important for adjusting calcination
conditions to achieve best calcined coke quality.
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