Improved Design Of The Combustion System Of Regenerative Heating Furnace Based On CFD Simulations

The regenerative heating furnace, using the high temperature air combustion (HTAC) technology, is a new kind of energy-saving furnace. It has many advantages, such as low emission of NOx and CO2, high thermal efficiency and so on. Therefore, the regenerative heating furnace has been widely used all over the world. While many problems, such as poor heating qulity, incomplete combustion of CO and so on, have come up when this kind of furnace in China is put into operation because of control systems, equipments themselves or other reasons at present. To enhance the performance of the regenerative furnace has become a serious problem which has to be solved as soon as possible in China's steel industry.The combustion system includes the regenerative burner system, the combustion control system and so on. It is the key factor which can affect the regenerative heating furnace's running. In order to enhance the performace of the regenerative heating furnace, improved design of the combustion system should be done at first. In this work, taking a regenerative heating furnace of BaoSteel for example, three improved designs of the combustion system of the furnance has been done via computational fluid dynamics (CFD) in order to improve the furnace's performance. These improved designs are general and can provide some help and reference to others to improve the performances of other regenerative heating furnaces in China.The main content of this work can be divided into four parts:(1) Design of the slab ingot mathematical model. A study of the slab mathematical model in L2 combustion control system of the regenerative heating furnace was carried out based on the three dimensional(3D) CFD simulation, and then a new slab ingot mathematical model was proposed based on the simulation data in order to predict the temperature of the slab ingot more accurately.(2) Optimal design of the vent angle of regenerative burner. A study of the"double high"phenomenon of the regenerative heating furnace was carried out based on the 3D CFD simulation of the combustion of the furnace, and then a new method to optimize the angle between the regenerative burner's secondary air vent and fuel vent was proposed based on the simulation data in order to improve the mixing performance of the regenerative burner and reduce the pollution emission of the regenerative reheating furnace (especially CO).(3) Design of the combustion mode. A study of the bad temperature distribution of the regenerative heating furnace, which means the temperature in the middle of the furnace is higher than those on both sides, was carried out based on the 3D CFD simulation of the combustion of the furnace, and then a new combustion mode of the regenerative heating furnace, which is called"diagonal mode", was proposed based on the simulation data in order to improve the temperature distribution.(4) Implementation of the new combustion mode. The PLC control program was modified according to the logic of the new combustion mode which was proposed in (3), and then an offline simulation was done though S7-PLCSIM and WinCC for debugging and verification to get the correct"diagonal mode"program.