Mathematical modeling of gas dynamics and off-gas post-combustion above the melt in a melter-gasifier furnace

Abstract

Organization of technological process and design of a furnace significantly affect the parameters of post-combustion, determining the need to develop a mathematical model of post-combustion zone. Modeling of gas dynamics, chemical reactions, convective diffusion and heat transfer in the gas phase above the melt was carried out in an experimental melter-gasifier furnace at three different values of mass flow rates and two positions of post-combustion tuyeres. Temperature distributions and off-gas components concentrations were obtained. It was found that at the lower position of the tuyere, post-combustion is carried out in the area of reflected jet, stagnant zones are formed around the tuyere and between the reflected jet and the melt surface, which decrease the post-combustion level. At the upper position of the tuyere, post-combustion occurs inside the primary jet, intensive mixing of all components of the furnace atmosphere occurs, post-combustion undergoes more completely, which leads to an increase in the off-gases temperature with an increase in uniformity of temperature fields and concentrations compared with the lower position of the tuyere. At the lower position of the tuyere, the flame zone turns out to be open, its shape significantly depends on the mass flow, and the flame zone volume increases with an increase in the mass flow. At the upper position of the tuyere, the flame zone is closed, with an increase in the mass flow, its shape does not change, but the flame zone volume decreases. For reduction processes in slag melt, the upper position of the tuyere is preferable, while for production of the producer gas at the furnace outlet, position of the tuyere closer to the melt surface is preferable.