The heat-technological process optimization of a moving dense multilayer weight of phosphorite pellets drying process by the energy-resource efficiency criterion
Statement of the problem: the problem of fuel and energy resources rational use is the most important one for energy-intensive industrial production, including the thermal preparation of pelletized raw materials in a complex multi-stage heat-technological system (HTS) by a horizontal-grate machine for the phosphorite pellets production. The drying modes optimization of a moving dense multilayer weight of phosphorite pellets in a complex HTS will increase the energy and resource efficiency of HTS as a result of heat-mass exchange processes (HMP) augmentation and optimization at an energy and heat minimum cost. The aim of the work is to increase the energy-resource efficiency of HTS, using the mathematical and computer model, the heat-technological process (HTP) optimization of the moving dense multilayer weight of phosphorite pellets drying process, characterized by the use of discrete dynamic programming and the control of the moisture redistribution effect by the height of the pellets multilayer backfilling, which allows to prevent the appearance of waterlogging horizons, negatively affecting the multilayer pellets weight gas permeability, that leads to unnecessary energy consumption increase and reduction of HTS performance in general. The methods used: system concept, discrete dynamic programming, optimal control theory of distributed parameters system, conditional multi-criteria optimization, computational mathematics. The result: the content and mathematical statements of the optimization problem (HTP) for moving dense multilayer weight of phosphorite pellets drying process in the complex multistage (HTS) horizontal-grate machine that is characterized by the heat-technological features of this horizontal-grate machine, the internal moisture transfer process intensity in the pellet and the waterlogging of sepatare pellets layers processes and gas-coolant, which allows to increase energy efficiency through intensification of dynamic multilayer drying HMP were submitted. Novelty: mathematical and computer models for optimizing the a moving dense multi-layer weight of phosphorite pellets drying HTP have been developed, which have made it possible to optimize the energy and resource efficiency of a complex dynamic phosphate pellet production HTS. The obtained results were used to calculate the energy-efficient drying of pellets in the HTS by a horizontal-grate machine. It was also found out that there is no waterlogging zone in the optimal mode of multilayer pellets drying, that HMP are intensified, the energy consumption is reduced and the end-product quality is increased, the share of return is reduced, that provides resource saving.