Oxygen Sensor Validation and Analysis of Process Air Oxygen Content at United Taconite

Abstract

CFX-TASCflow CFD Fortran formerly used to simulate magnetite oxidation and heat transfer between a pellet bed and cross flow gas stream has been revised and converted to ANSYS CFX 11 Command Expression Language for use in CFX11 CFD Cooler models. The conversion has been validated and found to yield consistent results when compared to the previous FORTRAN version. However, revision of the heat of reaction expression for magnetite oxidation now generates more heat release in the bed than the previous version, yielding higher predicted gas and solids temperatures under similar operating conditions. Future studies should focus on methods of estimating pellet entry temperature, incoming magnetite content, and cooling fan flow from plant measurements, to determine if current methods of estimation over-predict magnetite mass flow and solids entry temperatures, and under-predict cooling fan flow rates, as a means to resolve the trend toward higher temperatures in the model simulations. Most of the existing TASCflow cooler grids were found incompatible for CFX 11 simulations, necessitating development of new grids using Solid Works modeling software.