Development of the Vertical Swirling Melting Furnace with Multistage Air Nozzles for a Municipal Solid Waste Gasification and Melting System

Abstract

The melting furnace of a municipal solid waste gasification and melting system must have a high slag recovery rate and low dioxin emission. In this study, we developed a vertical swirling melting furnace with multistage air nozzles which can be used in the gasification and melting system. Three stage nozzles for feeding air and fuel are installed on a cylindrical furnace. Each nozzle is arranged in a tangential direction to generate swirling flow. The fuel is supplied by the primary nozzle which is located at the lowest level among the nozzles. Combustion air is supplied by the secondary and tertiary stage nozzles. The flow pattern of this furnace is similar to that of a cyclone separator. Most of the fuel goes down to the bottom of the furnace and burns in the swirl flow. The furnace design was done using a one-dimensional heat balance simulation tool. In this simulation, distribution of air mass flow in the furnace was determined by an air flow model experiment. The simulation results were compared with measured data from a 20t/day demonstration plant, and accuracy of the developed design tool was verified. The temperature prediction error was less than 40 degC. In the demonstration plant, the slag recovery rate of the melting furnace was higher than 90%, and the dioxin concentration in the flue gas at the chimney was lower than the government regulation value.