Study On Application Of HTAC In Metallurgy And Its Optimization With Numerical Simulation

High Temperature Air Combustion (HTAC) is one of the most important innovations in the field of combustion and thermal process. Its study is of momentous theoretical and practical significance for further development and application of HTAC technology.In this thesis, the feature of combustion process of HTAC and the whole thermal process including fluid flow, combustion, and heat transfer in ladle baker and heating furnace were studied experimentally and numerically. Combined with computational heat transfer, mass transfer, computational combustion, commercial software CFX4.3 integrated with some user fortran program has been used to investigate the fluid flow, gas combustion, NOx formation, and heat transfer in ladle baker and billet heating furnace. The principal contents of this work are summarized as following:(1) The basic principle, main characteristics, present status and perspective of HTAC technology is illustrated. The method to obtain high temperature and diluted air is discussed, and the characteristics of HTAC and its high efficiency of heating are studied.(2) The operation conditions of ladle and the development of ladle baking technology are systematic summarized. An on site study method of ladle baking was developed and accomplished in several commercial HTAC ladle heating system respectively to investigate the application of HTAC technology on ladle baker.(3) The uniformity of heating in two types of HTAC ladle bakers and combustion feature of high temperature and diluted air in ladles are analyzed based on three-dimensional HTAC mathematical model with multi-inlets and multi-outlets. The influences of preheating temperature and gas-flow rate on combustion are studied. The results of simulation and measurement are compared and the reason of error is analyzed.(4) The influences of the distance between air jet and gas jet and the relative position between inlet and outlet on gas temperature profile, oxygen concentration profile and NOx emission in combustion chamber of ladle areapproached based on the numerical optimizing research on 160t regenerative baker in Tangshan Iron and Steel Company (TISCO).(5) The transient process of HTAC switching combustion is studied numerically, which shows the combustion feature at the moment instantly after switching.(6) The influences of components and heat values of various fuels on temperature distribution and NOx emission are presented to investigate the fuel adaptability of HTAC system. The peak value of flame temperature, the length and shape of flame are different when various fuels are used. The flame temperature will rise and the flame volume will expand with the heat value of gas increasing, and the NOx emission amount will grow with increasing percentage of CH4 and H2 in gas.(7) The HTAC process and billet heating process in heating furnace and present status are described. Based on commercial software CFX4.3 and some self-programming codes, a three-dimensional CFD simulation system for simulating HTAC process in continuous heating furnace is developed. The entrancement, combustion and billet heating process in furnace are analyzed numerically, and the computational results were compared with production records and onsite measurement, which verified the practicability of this CFD system. The effect of combustion compound modes on the heating extent and distribution of fluid flow, temperature and concentration are simulated on various work conditions, which can provide references for the design and development of HTAC heating furnaces.