Numerical simulation of thermal-hydraulic processes in the riser chamber of installation for clinker production

Abstract

Clinker burning process has a decisive influence on energy consumption and the cost of cement production. A new problem is to use the process of decarbonization of alternative fuels from waste. These issues are particularly important in the introduction of a two-stage combustion of fuel in a rotary kiln without the typical reactor-decarbonizator. This work presents results of numerical studies on thermal-hydraulic phenomena in the riser chamber, which will be designed to burn fuel in the system where combustion air is supplied separately from the clinker cooler. The mathematical model is based on a combination of two methods of motion description: Euler description for the gas phase and Lagrange description for particles. Heat transfer between particles of raw material and gas was added to the numerical calculations. The main aim of the research was finding the correct fractional distribution of particles. For assumed particle distribution on the first stage of work, authors noted that all particles were carried away by the upper outlet to the preheater tower, what is not corresponding to the results of experimental studies. The obtained results of calculations can be the basis for further optimization of the design and operating conditions in the riser chamber with the implementation of the system. Keywords: Two-phase flow; Precalcination; Particle distribution; CFD

Parametric Studies of Cement Production Processes

“…Therefore, following these complex issues which contribute to the inefficient energy use and emissions in cement kiln systems, there is a strong need to use computer-aided modelling to simplify the work of analyses. Other studies have tried to vary fuel properties, primary-and secondary air settings, and fuel feed location to study the effect of the operational setting on refuse-derived fuel, where the results show a good applicability of the presented modelling procedure [2][3][4][5].…”

“…There are several process parameters in a cement rotary kiln system, which should be studied in order to observe trends that may indicate problems and provide necessary mean data for process analysis. The most important kiln controlling parameters are clinker production rate, fuel flow rate, specific heat consumption, secondary air temperature, kiln feed-end temperature, preheater exhaust gas temperature, ID fan pressure drop, kiln feed-end percentage oxygen, percentage downcomer oxygen, primary air flow rate, specific kiln volume loading, specific heat loading of burning zone crosssection area, and cooler air flow rate including temperature, pressure, and oxygen profile of the preheater [1][2][3][4]. However, the principal control variables are burning zone solid material temperature typically aimed at T brn = 1500°C; feed-end gas temperature typical at T brn = 1000°C; and feed-end oxygen typical at 2% [1].…”

“…Cement production processes involve complex chemical and physical reactions during the conversion of raw materials to the final product. Moreover, the clinker burning process, which has a decisive influence on energy consumption and the cost of cement production, involves the combustion reaction of fossil fuel and a complex heat exchange between solids from raw materials and hot combustion gases [2,3]. It also involves mixing, as well as separation of solid and fluids at various compositions, temperatures, and pressures.…”

“…3 Journal of Energy observed that most of the studies concerning modelling and simulation of cement manufacturing processes that can be found in the literature are based on computational fluid dynamics (CFD) and use the ANSYS Fluent package. This software allows the modelling of the effect of surface condition and phase changes of the material, as well as the optimization of fluid flow, material feed, and containing structure [2][3][4][5]. Furthermore, by considering the nature of cement production, specific needs and purpose of conceptual process design, and research experience from the other authors [36][37][38][39], they identified the Aspen Plus software as the most suitable tool for flow sheeting modelling and simulation of cement plants.…”

Modification of the inlet to the tertiary air duct in the cement kiln installation

“…In recent years, extensive work has been carried out with the aim of reducing energy consumption during cement production and gas emission reductions resulting from the use of alternative fuels from waste (Borsuk et al, 2016). Co-combustion of alternative fuels with coal in a rotary kiln is increasingly being considered as one of the environmentally friendly ways of disposing of waste.…”