02364nas a2200169 4500008004100000022001400041245008500055210006900140260007100209300001400280490000700294520172000301100002702021700001602048700001902064856011102083 2006 eng d a0888-588500aModeling of rotary cement kilns: applications to reduction in energy consumption0 aModeling of rotary cement kilns applications to reduction in ene a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR a2315-23300 v453 a

Rotary cement kilns are used for converting calcineous raw meal into cement clinkers. In this paper, we discuss and evaluate possible ways of reducing energy consumption in rotary cement kilns. A comprehensive one-dimensional model was developed to simulate complex processes occurring in rotary cement Kilns. A modeling strategy comprising three submodels. viz. a model for simulating the variation of bed height in the kiln, a model for simulating reactions and heat transfer in the bed region, and a model for simulating coal combustion and heat transfer in the freeboard region, was developed. Melting and formation of coating within the kiln were accounted for. Combustion of coal in the freeboard region was modeled by accounting for devolatilization, finite-rate gas-phase combustion, and char reaction. The simulated results were validated with the available data from three industrial kilns. The model was then used to understand the influence of various design and operating parameters on kiln performance. Several ways of reducing energy consumption in kilns were then computationally investigated. The model was also used to propose and to evaluate a practical solution of using a secondary shell to reduce energy consumption in rotary cement kilns. Simulation results indicate that varying kiln operating variables, viz. solid flow rate or RPM, can result only in small changes in kiln energetics. Use of a secondary shell over the kiln and energy recovery by passing air through the annular gap between the two appears to be a promising way to achieve significant energy savings. The developed model and the presented results will be useful for enhancing the performance of rotary cement kilns.

1 aMujumdar, Kaustubh, S.1 aArora, Amit1 aRanade, V., V. uhttp://library.ncl.res.in/content/modeling-rotary-cement-kilns-applications-reduction-energy-consumption-002577nas a2200217 4500008004100000022001400041245011100055210006900166260010600235300001400341490000700355520170900362653001102071653002302082653003102105100002702136700001902163700002502182700002202207856013002229 2007 eng d a0009-250900aRotary Cement Kiln Simulator (RoCKS): integrated modeling of pre-heater, calciner, kiln and clinker cooler0 aRotary Cement Kiln Simulator RoCKS integrated modeling of prehea aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAY a2590-26070 v623 a

This paper presents an integrated reaction engineering based mathematical model for clinker formation in cement industry. Separate models for pre-heater, calciner, rotary kiln and cooler were initially developed and coupled together to build an integrated simulator. Appropriate models for simulating gas-solid contact and heat transfer in pre-heaters were developed. Calciner was modeled by considering simultaneous combustion of coal particles and calcination of raw meal. Complex heat transfer and reactions (solid-solid, gas-solid and homogeneous reactions in gas phase) in rotary kiln were modeled using three sub-models coupled to each other. Solid-solid reactions in the bed region of the kiln were modeled using pseudo-homogeneous approximation. Melting of solids in the bed and formation of coating within the kiln were accounted. Clinker cooler was simulated by developing a two-dimensional model to capture cross-flow heat transfer between air and hot clinkers. The individual models were coupled with each other via mass and energy communication through common boundaries. The coupled model equations were solved iteratively. The model predictions agree well with the observations and experience from cement industry. The model was used to gain better understanding of influence of operating conditions on energy consumption in cement plant. Several ways for reducing energy consumption were computationally investigated. The integrated model, the developed software RoCKS (for Rotary Cement Kiln Simulator) and results presented here will be useful for enhancing our understanding and for enhancing the performance of clinker manufacturing. (C) 2007 Elsevier Ltd. All rights reserved.

10acement10aenergy consumption10areaction engineering model1 aMujumdar, Kaustubh, S.1 aGanesh, K., V.1 aKulkarni, Sarita, B.1 aRanade, Vivek, V. uhttp://library.ncl.res.in/content/rotary-cement-kiln-simulator-rocks-integrated-modeling-pre-heater-calciner-kiln-and-clinker02341nas a2200205 4500008004100000022001400041245004000055210004000095260006800135300001200203490000600215520173000221653001101951653000801962653002001970653002301990100002702013700002202040856007302062 2008 eng d a1932-214300aCFD modeling of rotary cement kilns0 aCFD modeling of rotary cement kilns a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcAPR a106-1180 v33 a

Rotary cement kilns are widely used to convert calcineous raw meal into cement clinker, and are key components in the cement industry. In this article, we report a comprehensive computational fluid dynamics (CFD)-based model to capture key transport processes in rotary cement kilns. Separate but coupled computational models were developed for the bed and the freeboard regions of the rotary kiln. The complex swirling airflow produced by kiln burners, coal combustion, gas-phase combustion of volatile matter and radiative heat transfer in the freeboard region were modeled. The clinkerization reactions in the bed region were modeled assuming solids as pseudo fluids. Coating formation in cement kilns (for both bed and freeboard regions) was considered. Appropriate source and sink terms were developed to model transfer of CO(2) from the bed to the freeboard region due to calcination reaction in the bed region. The developed bed and freeboard models were coupled by mass and energy communication through common interface. These coupled computational models were able to quite satisfactorily predict the available data from industrial kilns and previously published results. The computational models were also able to capture the intricacies of the burning zones of rotary cement kilns for changing burner-operational parameters like axial to swirl ratio and oxygen enrichment. The developed approach, computational models and simulation results will not only help in developing better understanding of cement kilns but also provide quantitative information about influence of burner design and other design parameters on kiln performance. (C) 2008 Curtin University of Technology and John Wiley & Sons, Ltd.

10aburner10aCFD10acoal combustion10arotary cement kiln1 aMujumdar, Kaustubh, S.1 aRanade, Vivek, V. uhttp://library.ncl.res.in/content/cfd-modeling-rotary-cement-kilns-0