Analysis of transport phenomena in a rotary-kiln hazardous waste incinerator (original) (raw)
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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.
Combustion Modeling of a Rotary-Kiln Hazardous Waste Incinerator
Hazardous waste has very complicated chemical compositions in a variety of physical forms and is difficult to characterize. Due to the complex transport phenomena within the incinerator the incineration process expects large uncertainties in the process chemistry and thermal/ emission control. For better understanding of the incineration process, process simulation was conducted using Computational Fluid-dynamics (CFD) to characterize temperature and species distribution in the incinerator. Hazardous waste in various forms is firstly converted to a hydrocarbonbased virtual fuel mixture. The combustion of the simplified waste was then simulated with a global 3-gas and an extended 7-gas combustion model. The distribution of temperature and chemical species is broadly investigated. The predicted temperature distribution has been validated with available measurement data from the operating rotary kiln waste incinerator AVR-Chemie in the Netherlands. New statistical post-processing of the standard CFD-output has been developed to give an overview of the average temperature profile and overall reactor behavior as valuable contribution to process control. Finally, an attempt has been made to simulate the multi-phase flow of the shredded solid waste within the incinerator in order to optimize the burner design.
Thermal treatment of hazardous wastes: a comparison of fluidized bed and rotary kiln incineration
Energy & Fuels, 1993
Large volumes of sludge are produced by a wide variety of industrial processes and by municipal waste water treatment. Interest in incinerating these sludges, either alone or co-fired with other fuels, is increasing. The issues surrounding sludge incineration in rotary kilns and fluidized beds were identified through a series of pilot-scale tests using two slightly different paper mill sludges.
Flow Behaviour of Shredded Solid Waste in a Rotary Kiln Hazardous Waste Incinerator
2004
Rotary kilns are widely used for incineration of hazardous waste with complex chemical compositions and physical forms. The solid waste used to be burnt through containers in the rotary kiln, which leads to serious process instability. Recently AVR-Chemie, a hazardous waste incineration company in the Netherlands has implemented a solid waste homogenisation plant where the containerised solid waste is shredded into small particles. The shredded solid waste is incinerated subsequently in the kiln so as to get better combustion efficiency and smoother process operation. It is obvious that the particle trajectory and the mixing of the solid particles with combustion air depend very much on the design and operation parameters. But the solid particle behaviour under current furnace and operating conditions is so far not clear. Thus, process simulation and optimisation are conducted to study the flow and mixing behaviour of the shredded solid waste so as to assist an optimal design of the feeding system. The current paper addresses the recent results in modelling the solid particle flow and mixing behaviour, by using computational fluid dynamics (CFD) technique. The knowledge gained will be used for the design optimisation in an industrial scale rotary kiln incinerator at AVR-Chemie.
Waste and Biomass Valorization
The present paper focuses on developing a novel virtual representation framework for optimizing standalone hazardous waste rotary kiln incineration plants. A digital support tool can be provided to optimize the plant's waste management, operation, and maintenance by combining thermochemical-based simulation models with a fuel classification system. First of all, the virtual representation can be used to determine the waste composition of not entirely analyzed waste streams. Furthermore, the determined waste compositions of historically fed waste streams can be used to enable further advanced applications. The determined waste compositions are linked with the appropriate waste code and supplier, which first enables the monitoring of the delivered waste streams. In the case of recurring fractions, the virtual representation can be used to optimize the barrel sequence to reach homogenous waste inputs. Additionally, the plant operation can be optimized regarding stable operation con...
Incineration of Hazardous Waste: A Sustainable Process?
Waste and Biomass Valorization, 2014
The first objective of any waste policy should be to minimize the negative effects of the generation and management of waste on human health and the environment. Re-use and recycling of waste, although of high priority in the waste hierarchy, is not necessarily always the best treatment method. In the case of hazardous waste containing toxic components, thermal treatment with energy recovery constitutes a cost effective treatment option, complying with the pillars of ''Sustainability'' and the requirements of ''Resource Efficient and Cleaner Production''. Iron recovery from the incineration ashes, water recycling, substitution of fossil fuel by high calorific waste in the incineration process, and energy recovery, avoid the use of non-renewable resources. Emissions to air and discharges to water of a typical rotary kiln for the incineration of hazardous waste, are far below the European emission limit values. Furthermore, recent studies on health effects of modern, state-of-the art waste incinerators show that any potential damage to the health of those living close-by or working in a hazardous waste incineration plant, is likely to be very small, if detectable.
Appendix A: Waste Incineration in Europe
Incineration is used as a treatment for a very wide range of wastes. Incineration itself is commonly only one part of a complex waste treatment system that altogether, provides for the overall management of the broad range of wastes that arise in society.