Optimizization Of Combustion Control System For Continuous Annealing Furnace Of Ansteel’s AA2 Unit

Today there is an excess capacity in the iron and steel market. As the sale price is keeping low and the competition is turning white-hot day by day, the requirement for product’s quality has even reached an unprecedented high level. Silicon steel product is the art and craft of iron and steel product; it has extremely strict requirements for the technology of heating processing, so any deviation in temperature control will directly affect the iron loss or magnetic induction of the product. To improve product quality and meet the demand under various working conditions, we have to keep improving and optimizing the annealing process of silicon steel product.Starting with the original structure and combustion control system of the continuous annealing furnace(CAF) in the Cold Rolling Silicon Steel Plant, Anshan Steel Co., Ltd.(hereinafter referred to as “the silicon steel plant”), combining the control requirements and features of the CAF, this article analyzes the current troubles of combustion control system in the CAF of AA2 unit in the silicon steel plant and targetedly optimizes the scale-free heating section and radiant tube heating section.The furnace temperature of each section is controlled by utilizing Yokogawa DCS(Distributed Control System) in accordance with the features of temperature control system of CAF, integrating with the theories of cross limiting amplitude and closed loop feedback. By analyzing the ratio of air to gas and other influencing factors, we build the relation between every control parameter in each furnace section, and establish the transfer function of the annealing furnace combustion system.Applying the method of timing pulse combustion control to the optimization for No.2 radiant tube heating section of AA2 CAF, we reduce the surface oxidation of the strip steel, increase the heating efficiency, and promote the energy conservation and environmental protection.Based on the existing steel grades and temperature control curves, we verify the optimized combustion control system, making the strip steel heated to the temperature required by annealing process. It is proved that the optimized combustion control system not only enhances the control precision but also is convenient for operation and maintenance, and plays an important role in the improvement of product quality and the safe and stable operation of production.