Kurtul KÜÇÜKADA, Ebru MANÇUHAN, Emre ALPMAN

Mathematical modeling and simulation of the preheating zone of a tunnel kiln

Bu çalışmada tünel fırın ön ısıtma bölgesi simülasyonu için gaz akışı, tuğla-hava arasında gerçekleşen ısı transferi, tuğladaki bağlı suyun buharlaşmasını tanımlayan tek boyutlu model denklemleri çıkarıldı. Model denklemleri çözülerek proses değişkenlerinin (fırın iç gazının debi, sıcaklık ve nemi, tuğla yüzey sıcaklığı ve tuğlada ki bağlı su kesri) ön ısıtma bölgesi boyunca değişimi bulundu. Yüksek kaliteli tuğla üretiminde gerekli olan gaz sıcaklık profilini elde edebilmek için besleme nokta ve debileri farklı iki çevre havası profili önerildi. Sanayi tipi bir tünel fırından ölçülen sonuçlar ile simülasyon sonuçları karşılaştırıldığında önerilen çevre havası profillerinin uygulamada kullanılabileceği görüldü. Ön ısıtma bölgesi girişinde yaklaşık 20$0^ 0 C$ olması gereken gaz sıcaklığının çevre havası beslenmediği durumda$350^ 0 C$’ye çıktığı görüldü. Boyutsuz ön ısıtma bölgesi uzunluğunun yaklaşık %70’inde tuğla bağlı suyunun buharlaştığı belirlendi.

Tünel fırın ön ısıtma bölgesinin matematiksel modeli ve simülasyonu

Simulation of drying bricks in the preheating zone of a tunnel kiln was done by developing a one dimensional model describing the gas flow, heat transfer between gas and bricks and evaporation of bound water. Simulation results were compared to the previously measured plant data. Ambient air was fed into the preheating zone using two different profiles and vent locations to achieve desired gas temperature for high quality bricks. Temperature profiles obtained using both approaches agreed well with measurements. When no ambient air is fed, gas temperature was shown to reach 35$0^ 0 C$ at the preheating zone entrance which is not desired for the best quality product. Bound water in the bricks, which should be evaporated completely, approaches zero while reaching the 70% of the dimensionless length of the preheating zone.

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Abou-Ziyan, H. Z. Convective heat transfer from different brick arrangements in tunnel kilns. Appl. Therm. Eng. 24, 171-191, 2004
Dugwell, D. R and Oakley, D. E. Simulation of tunnel kilns for firing refractory products. British Ceram. Trans. J. 86, 150-153, 1987.
Dugwell, D. R and Oakley, D. E. Correlation of convective heat transfer data for tunnel kilns. J. of the Inst. of Energy 61, 165-171, 1988.
Dugwell, D. R and Oakley, D. E. A model of heat transfer in tunnel kilns used for firing refractories. Int. J. Heat Mass Transfer 31, 2381-2390, 1988.
Geankoplis, C.J. Transport Processes and Separation Process Principles (4th Ed.), Prentice Hall; Upper Saddle River, New Jersey, 2003.
Halasz, G.; Toth, J and Hangos, K. M. Energy optimal operation conditions of a tunnel kiln. Comput. Chem. Eng. 12, 183-187, 1988
Holman, J.P. Heat Transfer (9th Ed.), Mc Graw-Hill; New York, 2001.
Kaya, S.; Küçükada, K. and Mançuhan, E. Model-based optimization of heat recovery in the cooling zone of a tunnel kiln. Appl. Therm. Eng. 28, 633-641, 2008.
Kaya S.; Mançuhan, E. and Küçükada, K. Modelling and optimization of the firing zone of a tunnel kiln to predict the optimal feed locations and mass fluxes of the fuel and secondary air. Appl. Energy 86, 325-332, 2009.
Mançuhan, E. Analysis and optimization of drying of green bricks in a tunnel dryer. Drying Techn. 27, 707-713, 2009.
Mançuhan, E. and Küçükada, K. Optimization of fuel and air use in a tunnel kiln to produce coal admixed bricks. Appl. Therm. Eng. 26, 1556-1563, 2006.
Michael, P. and Manesis, S. Modelling and control of industrial tunnel-type furnaces for brick and tile production. Proceeding of the 5th Int. Conference on Technology and Automation, Thessaloniki, Greece. 216-221, 2005.
Moropoulou, A; Karoglou, M; Giakoumaki, A; Krokida, M.K; Maroulis, Z.B and Saravacos, G.D. Drying kinetics of some building materials. Brazilian J. of Chemical Eng. 22, 203-208, 2005.
Prasertsan, S., Theppaya, T., Prateepchaikul, G. and Kirirat, P. Development of an energy-efficient brick kiln. Int. J. of Energy Research, 21, 1363-1383, 1997.
Raimondo, M., Dondi, M., Gardini, D., Guarini, G. and Mazzanti, F. Predicting the initial rate of water absorption in clay bricks. Contruction and Building Materials 23, 2623-2630, 2009.
Rao S., S. Applied Numerical Methods for Engineers and Scientists (4th Ed.), Prentice Hall; Upper Saddle River, New Jersey 2002.
Yu B. Dynamic modeling of a tunnel kiln. Heat Transfer Engineering 15, 39-53, 1994.