Thermal Process Simulation of Reactive Particles on Moving Grates

schnellere Rostgeschwindigkeit, eine kleinere Kühlluftmenge, einen geringeren Klinkerdurchsatz oder eine größere Partikelgröße vermieden werden. Abstract The moving grates, or travelling grates, are widely used in industries. For the purpose of product quality improvement (in quenching of clinker), energy consumption reduction (in pre-heating of limestone), emission control (in waste incineration) or to tackle some special operation problems (such as over heating of grates or fluidisation of fine particles), it is important to simulate the physical and chemical phenomena in the gas-solid systems on the moving grates. In this dissertation, two numerical bed models with cell method were established to Simulation of reactive particles on moving grates. Program LEPOL simulated the drying, pre-heating and partial calcination of limestone particles on a travelling LEPOL-Grate, which was built in front of a lime rotary kiln. The main purpose of the simulation was to show how to decrease the average or peak temperature of the hot gas when it reaches the LEPOL-Grate, in order to protect the grate from the gas heat. This could be achieved effectively by reducing the hot gas amount with a gas bypass at the roof of hot gas chamber. As a part of above program, one-dimension steady-state shrinking core models were built for the decomposition of limestone and magnesite. For dolomite, furthermore, both separate and simultaneous decomposition models of MgCO 3 and CaCO 3 components in dolomite were established. A method was described to evaluate the reaction rate coefficients, pore diffusivity and thermal conductivity during decomposition of the three earth alkalis of different types and origins, by linearization of conversion curves. Another program, CLINKER, simulated the rapid cooling down of clinker particles on a similar moving grate. The purpose of the simulation was to find some methods to avoid the fluidisation of smaller clinker particles. The fluidisation phenomena of smaller clinker particles could be avoided by a prolonged grate, a rapid grate velocity (means correspondingly a smaller clinker particle bed height), smaller air input amount, smaller clinker through-put or bigger clinker particle size.