Aspen Plus-based simulation of a cement calciner and optimization analysis of air pollutants emission

The cement industry is a typical high energy consumption and heavy pollution industry, in which amounts of CO(2), NO, NO(2), and SO(2) discharge from the pre-calciner kiln system and cause severe greenhouse and acid rain effects. Meanwhile, reasonable division of the combustion environment in the calciner is the main method to control the formation of pollutant gases. In this article, a calciner process model in Aspen Plus is proposed based on the combustion mechanism analysis of the Dual Combustion and Denitration calciner (DD-calciner) and verified by industrial data. Then, for a concrete DD-calciner, the article studies the effects of the flow rate of coal and tertiary air on flue gas compositions and effects of the staging combustion technology on the NO (x) , SO(2), and CO concentrations in the flue gas. Through comparing the model results with the relevant environmental standards, the optimization analysis for staging combustion parameters of the calciner is done, and the result shows that when the proportion of tertiary air entering the pyrolysis and combustion zone is controlled within the range of 57-65.52% (0.89 < alpha < 1.004), all the gas pollutants emit within accepted standards simultaneously. The calciner process model outlined in this article describes the key processes of the physical and chemical reactions in the calciner. It can be used to study the key operation and design parameters which influence the flue gas constituents, so as to provide data support for determining the pollutant emission reduction plan of the cement industries with a view to reduce air pollutant emission.