CEE Oct-Dec 2002

scan for high accuracy assurance. The scanner's hi gh optical resolut ion al lows the immedi ate detection of hot spots as smal l as I 0 em \. I 0 em. 1:. addition. hi gh-rrec i sion Ray tek portable IR thermometers are av ai IabIe far prevent i vc I predictive ma imenance as well as condition monitoring. Eve n temperatures of very small. or hard– to-reach targets in electrical system, includi ng swit ch boxes and transf ormer connections. can be easily monitored. New, powerful documentation capabilities bui lt into these instruments enhances repair and maintenance accountability and makes them vital fo r any elec trical or equipment service app lication. as well as for produc t qua lity assu rance and compliance certification. Cuurtesy : World Cement Sep. 2002. Pp 108- I 12, Enqui1y no. 30, Fox: +./4(0) 1252-718992 /:.'-mail : muil(a worldcement.com lJ R L: 11 11'11'. \l'orldcemenf. com MATHEMATICAL MODELS FOR THE CEMENT CLINKER BURNING PROCESS T he basic pri ncip les of th e ca lculations and the models of the preheater. ca lc incr, gas off-take , kiln and cooler have been described in the previous parts of the publ ica tion. In this lined part of the series of publications these models are combined to form a complete model which shou ld make it 'poss ible to improve the mode of operation of kil n plants. The effects of additional cyclone stages, the collecting el'licicncy of the cyclone stages. the dust burden of the kiln gas. the ope ration or a bypass. temperature. the distribution of the cooling air in the clinker, the depth of the clinker bed in the cooler and the lime content of the kiln mea l on the fuel energy requi rement and temperature profileof the kiln plant have been calcul ated as examples of the application of the model. Simp l ifi ed express ions for burning cement clinker in rotary ki ln plants in the cement industry have been combined in this work to form a mathematical model. It takes account of material as well as process engineering and pl ant processes and forms the basis for future work in which the mode of operati on of the pl ants is to be improved with respect to energy– sav ing and envi ronment al protect ion. The mode l provi des results which arc in agreement w ith the presen t und er standing of th e process. However, they can only be verifi ed in individual cases as it is not yet poss ible to make suf(iciently accurate measurements in all areas of the k iln plant. This applies, for exampl e, to measurements within the kiln and cooler. Measurements between the cyc lone stages, at the calciner and bypass, and at the kiln inlet and kiln hood are in fact possible but require cons id erab le effo rt. Further development of the poss ible measuring techniques for these areas is therefore desirable. Improvements to the model are needed, especial ly with respect to the material processes. From the energy point of view th ese processes can be comparable with plant and process engineeri ng factors and must therefore not be neglected in the energy and mass balances. They arc also important with respect to cl inker quality and lowering the sintering zone environmental protection . In 30 part icular, the reactions and recirculating systems of sulphur, chlorine and alkali s shou ld be incl uded in the model. Clinkt:r phase fo rmation m ust also be desc ribed more accurately to prov ide better covc rnge or the processes in the different zones of the kiln. From the process engineering point of view the very significant influence in the mode l of th e particle size distri but ion of th e cli nker on the heat transfer in the grate cooler should be checked with the aid of ope rational meas urement s. La borato ry measurements o f the radiation prope rties or the kiln feed could contribute to improved ca lculations of the heat tran sfer in the k i ln. Differentiation of the kiln feed on the basis or particle size fractions would permit a more sophist icated examinati on of th e collection characteristics of ~e preheater. Even in it s present state the model can be used to carry out theoretical investigation ofchanges i n a pl ant in advance . W ith a procedure ana logous to that used in th is work the changes can be assessed by comparison of the calculations fo r a referen ce cond iti on wi th the calc ul ated results for the modi fied plant. At present this primaril y concerns energy and materi al questions for optimizi ng the mode of operation. This will be extended in the future to cover emissions as part of a research project. Courtesy : ZKG !nternational Cement - Lime - Gypsum No.7/ 2002(Vo/.55), Pp25-37, Fax: ./9(0) 52./1 80 9-11 l.f E-mail: ansia. c::akanla)hertelsmann. de •