Numerical Modeling of a Rotary Kiln Incinerator (original) (raw)
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Dynamic modeling of waste incineration plants with rotary kilns
Chemical Engineering Science, 1998
Incineration is not a new technology and has been used to destroy organic hazardous waste for many years. Nevertheless, variability in waste composition and the severity of the incineration operating conditions may result in many practical operating problems, high maintenance requirements and equipment unreliability. Moreover, a large number of constraints must be satisfied. These constraints are imposed by permit, by design and by operating practice. The goal of this work is to present a dynamic model which is able to follow large variations in process conditions and to be of practical value from a control point of view. This paper deals in particular with the development of a dynamic model which describes the behavior of a rotary kiln (primary combustion chamber with heterogeneous combustion) as well as the corresponding afterburner system (secondary combustion chamber with homogeneous combustion) followed by a heat recovery system which completes the hot section of a typical incineration plant. Special attention was devoted to a start-up procedure which was used as a specific application, to check the robustness and reliability of the model itself effectively. In addition, a number of comparisons with experimental data available from commercial units are reported to complete the model validation under ordinary feeding conditions.
Combustion Modelling of a Rotary Kiln for Hazardous Waste Incineration
Incineration is an excellent disposal technology for all waste materials with heat release potentials, and provides high degree of toxic destruction and control for a broad range of hazardous materials. In the Netherlands, the hazardous wastes in various forms are processed at AVR-Chemie located at the Rotterdam harbour, through rotary kiln incinerators. The newly enforced regulations from the European Union with stricter emission levels require a better understanding of the incineration process and improved process control. However, the transport phenomena and combustion processes within the kiln system are very complex and not well understood. In order to get better understanding of the incineration process within the rotary kiln system, research was carried out to study the fluid flow and combustion behaviour of the incineration system. Computational Fluid-dynamics (CFD) was used to simulate the waste combustion process, and temperature measurements of the operating rotary kiln incinerator were conducted to validate the CFD model and to provide the information to kiln operators at AVR. This paper will present the latest results from the current research project for the simulation of gas flow and mixing, and combustion heat transfer for a wide range of hazardous waste streams.
Modelling of a clinker rotary kiln using operating functions concept
The Canadian Journal of Chemical Engineering, 2011
Modelling and parameter identification of complex dynamic systems/processes is one of the main challenging problems in control engineering. An example of such a process is clinker rotary kiln (CRK) in cement industry. In the prevailing models independently of which structure is used to describe the kiln's dynamics and the identification algorithm, parameters are assumed to be centralised and constant while the CRK is well known as a distributed parameter system with a strongly varying dynamic through time. In this work, the kiln's dynamic is described in the form of a state-space representation with three state variables using a system of partial differential equations (PDE). The structure is chosen so that it can easily be embedded in classical state-space control algorithms. The parameters of the PDE system are called operating functions since their numerical values vary with respect to different operating conditions of the kiln, to their position in the kiln, and through time. A phenomenological approach is also proposed in this paper to identify the operating functions for a given steady-state operation of the kiln. The model is then used to perform a semi-dynamic simulation of the process through manipulating main process variables.
Modeling of Surface Geometric Structure State After Integratedformed Milling and Finish Burnishing
Management Systems in Production Engineering, 2017
The article deals with computer-based modeling of burnishing a surface previously milled with a spherical cutter. This method of milling leaves traces, mainly asperities caused by the cutting crossfeed and cutter diameter. The burnishing process - surface plastic treatment - is accompanied by phenomena that take place right in the burnishing ball-milled surface contact zone. The authors present the method for preparing a finite element model and the methodology of tests for the assessment of height parameters of a surface geometrical structure (SGS). In the physical model the workpieces had a cuboidal shape and these dimensions: (width × height × length) 2×1×4.5 mm. As in the process of burnishing a cuboidal workpiece is affected by plastic deformations, the nonlinearities of the milled item were taken into account. The physical model of the process assumed that the burnishing ball would be rolled perpendicularly to milling cutter linear traces. The model tests included the applicat...
Design and finite element analysis of a wet cycle cement rotary kiln
Finite Elements in Analysis and Design, 2002
The ÿnite element method (FEM) is applied to the nonlinear analysis of a cement rotary kiln for the Ra s Hamidou factory (Algeria). The nonlinearity is due to contact conditions between the kiln body, tyres and foundations. The FEM is ÿrst used in a reduced model of the kiln in order to obtain the meshing criterion for the global model. Then, an overall FEM analysis is performed for the di erent operating and live loads at di erent positions of the rotary kiln. Stress and displacement components are evaluated based on the ASME rules (Asme Boiler and Pressure Vessel Code. VIII. Division 2-Alternative Rules. The American Society of Mechanical Engineers, 1995). Finally, in this work, the main design criterion is the out-of-roundness values at the kiln shell so that the thickness of the kiln shell is smaller in the central bend span than the values at the tyres.
Implementation of a Mathematical Modelling of a Rotary Cement Kilns
IPTEK The Journal for Technology and Science, 2019
Rotary cement kiln is the main equipment in the cement industry that has complex dynamic behavior, where any changes will affect the quality of the product and the consumed energy. A one-dimensional model of rotary kiln is needed to understand kiln's behavior and improve kiln operating and design to achieve the optimum condition of product quality and energy required. In this study, the onedimensional mathematical model of a dry rotary cement kiln with pulverized coal combustion is developed. This model consists of a set of nonlinear ordinary differential equations and nonlinear algebraic equations that describe material and energy balance equations. The model has been solved numerically by using Matlab R2015a, and it has been validated by comparing the result with published experimental data. Based on the result, the steady-state simulation shows that the behavior of the model developed is appropriate with the results presented in the literature. It can be concluded that the model is accurate (error < 6%) to describe the profile of temperature and bed composition along with the kiln. It can be used to obtain a better understanding of kiln's behavior and improve the kiln operating and design to achieve the optimum condition.
Modelling of a rotary kiln for the pyrolysis of aluminium waste
Chemical Engineering Science, 2005
This paper deals with the mathematical modelling of a rotary kiln which is used for the recycling of aluminium waste. This model is mainly based on the coupling between:"a bed model" describing the processes occurring within the bed of aluminium waste flowing inside the kiln, "a kiln model" describing heat transfer within the kiln itself, and, "a gas model" describing processes occurring within the gaseous phase held inside the furnace. The "bed model" is mainly based on a plug flow of particles of aluminium inside the kiln. Mass balances as well as energy balances allow for the prediction of the fraction of the organic material within the particles of aluminium as well their temperature. Relevant equations for the "kiln model" include heat conduction and heat exchange with solid and gaseous material. The equations for the "gas model" are mainly based on fluid mechanics equations coupled with turbulence, radiation, and combustion. The software Fluent TM will be used in order to solve this last model. In this paper, some insights will be given on the description of the "bed model" and "the kiln model" and on the procedure used for the coupling of these models. Exchange variables as well as solving procedure will also be included. Numerical results will be compared to experimental ones, obtained from the pilot scale rotary kiln at Alcan research centre
2017
In asphalt mixing plants, the rotary kiln is a massive machine whose function is to dry and heat a mixture of sand and gravel. The rotation of the kiln is transferred through supporting rings which are fitted to the drum shell by means of spokes. Loads acting on these spokes are both thermal and mechanical. Indeed, the rotary kiln is highly heated by a burner and loaded as well by its self-weight and the raw material passing through it. The spokes are welded onto both the supporting ring and the drum shell. Fatigue can lead after some time of operation to spoke or weld crack. In this article, a load investigation is carried out using analytical and numerical approaches. Stress results are obtained by finite element simulation and numerical model is compared with strain gauge measurements performed on an operating rotary kiln. Then, fatigue analysis is conducted to find the expected lifetime of both the spoke and the welds. Finally, an optimized redesign of the spoke is presented to ...
A Curve-Based Approach for Clean-up Machining
Computer-Aided Design and Applications, 2004
This paper presents a new efficient and robust tool-path generation methods for clean-up machining by employing a curve-based approach. The clean-up machining to be discussed in this paper are pencil-cut and fillet-cut for a polyhedral model of the STL form with a ball-end mill. The pencil-cut and fillet-cut paths are obtained from the curve-based scanning tool paths on the xz, yz, and xy planes. The scanning tool path has exact sharp-concave points and bi-contact vectors, both of which are very useful to detect 'pencil-points', trace the pencil-cut path, and generate the filletcut path. In the paper, some illustrative examples are provided, and the characteristics of the proposed method are discussed.