Mathematical modellin of injection processes

摘要

Submerged injection is widely used in pyrometallurgical processes for introducing reactants to reaction vessels such as smelters, and for ensuring high rates of reaction through rapid mixing. For some years, mathematical models have been applied to the prediction of bath circulation and bubble distribution in cases of low to moderate rates of gas injection with a reasonably high degree of success. These models, the most advanced models being so-called "multi-fluid models", have been steadily increasing in complexity and in the level of detail that they predict, including the spout region, splash and wave motion. This paper summarises the progress in modelling gas injection in general, and details in particular some work that has been done modelling wave motion. Air-water models of a generic upright cylindrical geometry have been used to determine the frequency and amplitude of waves generated in a liquid bath by bottom gas injection. Wave motion (or slopping) is found to couple strongly to motion of the gas-liquid plume for certain ranges of injection conditions. This behaviour has been modelled using a modal analysis model. Such modelling techniques can be used to optimize vessel geometry and injection location to minimize slopping or wave motion.