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TUNNEL KILN CAPACITY INCREASE WITH CFDESIGN
Our previous article in which we highlighted the advantages of the Motion module of CFdesign was about using the Upfront CFD tool for the simulation of a tunnel kiln. Now it is time to add some more details to this filed because the analysis of the tunnel kiln located near Budapest has reached it goals regarding capacity increase.
The tunnel kiln consists of 13 sections its overall length is 21.6 meters. The heat needed for the treatment is generated by 6 Kromschröder natural gas burners. The burners are operated in Flox mode where only pure natural gas is inserted and the gas burns inside the kiln this way reducing NOx values.
The changing of the height of the supporting structure was examined. We were interested in the effect caused by the 55 mm shorter supporting legs. The key point of this analysis was to determine the velocity of flow between two products (in small, 10mm gaps) since this property ensures the requested good heat treating results.
Flow velocities were satisfactory so while reducing the height of legs one more layer of products were fed into the kiln. Experts of the company modified the operating conditions of the kiln slightly because of the small increase in overall weight. After examining different payload schemes the maximum of capacity increase is now 20%.
The heat transfer analysis on the payload leaving the kiln was also carried out. The transient simulation highlighted the temperature differences between the outer and inner sides of the product. Recommendations for installing a shield around the payload to protect it from shocks of cold air would result in reduction of additional costs.
Just to release some information on what CFdesign is capable of, the whole geometry of the kiln – including the exhaust and cooling ductwork including the blowers – was modeled with 3.5 million fluid elements (960 000 nodes) which is the largest simulation we made during the past few years.
This analysis provided us with data on the general operating scheme of the kiln and also expressed the importance of exact settings of the exhaust fan.
If you would like to see and understand how the kiln behaves when gas volume flow changes or other arrangements of the payload can be a solution for capacity problems, send us an E-mail.
2006.08.06 - CFD Engineering Hungary Kft. |
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