Abstract
Each year a significant growth in the amount of wastes generated is observed. Due to this fact technologies enabling utilization of wastes are needed. One of the ways to utilizes wastes is thermal conversion. Most widely used technology for thermal conversion is gasification that enables to produce syngas that can be either combusted or directed to further synthesis to produce methanol or liquid fuels. There are several commercially available technologies that enable to gasify wastes. The first part of this study is subjected to general description of waste gasification process. Furthermore the analysis and comparison of commercially available gasification technologies is presented, including their process arrangement, limits and capabilities. Second part of the study is dedicated to the development of thermodynamic model for waste gasification. The model includes three zones of gasification reactors: drying, gasification and eventually ash melting. Modified Gibbs minimization method is used to simulate gasification process. The model is capable of predicting final gas composition as a function of temperature or equivalence ratio. Calculations are performed for a specified average wastes composition and different equivalence ratios of air to discuss its influence on the performance of gasification (temperature of the process and gas composition). Finally the model enables to calculate total energy balance of the process as well as gasification and final gas temperature.
Highlights
Thermochemical conversion of wastes, represented by gasification process, has a relatively short history, but since the beginning of 1990’s it became a commercially available technology
Main advantages of thermal conversion of wastes are: strong reduction of the waste in mass and in volume, destruction of organic contaminants, such as halogenated hydrocarbons, utilization of recyclables from the thermal residues, such as ferrous and non-ferrous metals from bottom ash and slag, reduction of greenhouse gas emissions from anaerobic decomposition of the organic wastes, land savings due the decreased volume resulting in smaller landfills [1-3]
Addition of steam as leads to the increased hydrogen concertation, which is desirable in case of using syngas for chemical synthesis
Summary
Thermochemical conversion of wastes, represented by gasification process, has a relatively short history, but since the beginning of 1990’s it became a commercially available technology. In case of combustion processes the feedstock is not that important as in case of pyrolysis, but amount of flue gas, which has to be cleaned, is very large (approximately 14 m3/kg waste) what increases both the equipment size and operational costs For this reasons gasification presents itself as a most advisable technology for waste conversion. This high temperature provides the possibility to utilize hazardous, toxic and medical wastes, which is not possible in case of lower temperature reactors To obtain such high temperature the feedstock need to be improved, which can be done by addition of met coke, that increases the calorific value of feedstock and serves as a kind of grate that enables molten ash to flow downward. The solution to that problem is to install upstream the additional equipment for a gas processing, for instance plasma reactor that will be able to increase the temperature up to at least 1500 K and reduce the amount of dioxins and other impurities in produced gas
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
