Thermodynamics Simulation Of Preheating-precalcining Whole Kiln System With High Solid-gas Ratio

Based on the theory of preheating-precalcining with high solid-gas ratio(HSGR) and the principle of "three transport and one reaction", the thermodynamics calculation mathematical model of the whole preheating-precalcining kiln system with HSGR has been established in this paper. The thermodynamics calculation of the system has been finished for the first time. Meanwhile, the calculation model has been validated by the data from the industry production and the engineering examination report. The calculation results agree well with these data.Influences of the cyclone separation efficiency, air leak, heat scatter and the feeding coal ratio of precalciner are also investigated in this paper. The results are shown as followings: 1) The thermal efficiency of preheating-precalcining system increases with the rising of separation efficiency of each stage cyclone, and the separation efficiency of first stage cyclone affects the thermal efficiency most greatly;B-series of the two cyclones in the same stage, especially for B1 in the first stage, affects the thermal efficiency more remarkably. 2) The thermal efficiency reduces linearly with the increasing of outer air leak coefficient. 3) The thermal efficiency decreases from 84.4% to 79.3% with the increasing of heat scatter coefficient from 0 to 10%, and heat scatter of the unit with high temperature affects the thermal efficiency obviously. 5) the feeding coal ratio has a optimization value. More or less, it's unfavorable for the heat distribution of the precalciner.On the basis of previous theory of effective energy fraction, the reactor in the previous theory model is further divided. A new mathematic expression of the thermal efficiency of the whole kiln system, including the four subsystems of preheater, precalciner, rotary kiln and cooler, is presented. The expression shows that the thermal efficiency of the whole kiln system is a linear superposition of thermal efficiencies of all four subsystems. The impacts of the effective energy fraction and the thermal efficiency of each subsystem are also analyzed. It shows that the precalciner plays the mostimportant role in the whole kiln system, and its thermal efficiency, together with the effective energy fraction affects the whole kiln system thermal efficiency most remarkable. Raising its thermal efficiency or decreasing the effective energy fraction could improve the whole thermal efficiency. This enriches and develops the previous theory of effective energy fraction.