Temperature field distribution of kiln tail of cement preclinkering technology

Abstract

If the temperature of raw meal to feed into rotary kiln is increased from 900°C to 1000~1200°C, the solid phase reaction and liquid sinter reaction will be significant enhanced, which will help increase clinker production significantly. Through calcinations condition comparison, this paper studied characteristics of temperature field distribution of kiln tail of cement preclinkering technology. Some results are found by system study. The ratio of tail coal of cement preclinering technology is about 70%, raw meal temperature can reach 1070°C, and flue gas temperature of C1 is still about 290°C. Introduction Since Aspdin obtained for cement invention patent in 1824, human beings began to use cement as the main building material of the era at large scale. Lasting nearly two hundred years, cement process equipment also changed. Cement kiln developed from vertical kiln, rotary kiln, preheater kiln to predecomposition kiln, far into the ecological environment type to meet the requirements of environmental protection. Predecomposition kiln technology has been the mainstream of cement clinker calcinations one over the past decades. However, as a bottleneck, the residual decomposition of calcium carbonate and the slowly temperature rising process in rotary kiln limit capacity growing and energy consumption reducing. The rates of heat transfer and need for the clinker burning is hugely imbalanced, which is the main contradiction. According to the previous research, if the temperature of raw meal to feed into rotary kiln is increased from 900°C to 1000~1200°C, the solid phase reaction and liquid sinter reaction will be significant enhanced [1-3]. In other words, the above process of enhancing the calcinations for raw meal in preclinkering furnace takes advantages of more efficient heat transfer under the suspension state, and the results are certificated to help increase the clinker production significantly. Through calcinations condition comparison, this paper showed a new type technology which called cement preclinkering technology [4]. And it is studied that characteristics of temperature field distribution of cyclone preheater and preclinkering furnace systems of cement preclinkering technology. Concept of cement preclinkering technology The process route of preliminary idea for cement preclinkering technology is shown in Figure 1.Firstly raw meal enters the preheater systems, and through multistage (four or five stages) gas-solid heat transfer inside cyclone preheaters, raw meal is preheated to 700~800°C. Raw meal enters the preclinkering furnace for chemical reaction and heat transfer, and after the last gas-solid separation inside high temperature cyclone preheater, raw meal temperature obtains 1000~1200°C. Then raw meal immediately enters shorter rotary kiln(L/D=8~10), in which clinker solid phase and liquid sinter 5th International Conference on Information Engineering for Mechanics and Materials (ICIMM 2015) © 2015. The authors Published by Atlantis Press 1359 process react during about 1000/1200~1450~1350°C. Lastly, clinker goes into cooler, then is gone out of that. Fig.1 Concept of cement preclinkering technology process Computational models A schematic of preheater unit considered for developing computational model is shown in Figure 2. Fig. 2 Schematic of cement preheater