Optimization And Application Of Laminar Cooling Process Automation System For Hot Strip Mill

Based on a laminar cooling project for a 1500mm hot strip mill, a process automation control system is developed. A series of control models for laminar cooling system are built based on the heat transfer theory. In view of the actual problems, a number of solutions and various cooling strategies and cooling modes are put forward. In order to ensure that the coiling temperature and mechanical properties are homogeneous, Feedback control system arithmetic is optimized and laminar cooling automation control system is developed. Since the online operation, the system has been running stable and reliable with a high precision, and mechanical properties of hot rolled strips are improved significantly.The main research contents and results are as follows:(1) The equipment and mathematical models of the laminar cooling control system are analyzed; Solutions for the problems existing in the process of cooling are put forward. Based on classical heat transfer theory, the air cooling and water coiling models are developed.(2) Laminar cooling process automation control system is developed based on the actual situation by Visual C++ language and consists of many functions which are detailed described in the paper, such as pre-setup calculation, modification setup calculation, feedback control, feed forward control and self-learning, etc.(3) Under the requirements of different temperature control mode, a series of cooling strategies and cooling modes are developed. The new programs such as accelerative rolling, hot head and hot tail, side covering are aiming at the temperature uniformity control of length, thickness and width direction, which ensure the product performance.(4) Introduce the fundamental principle of the controller. First-order inertia Smith control system is developed based on the primary PI arithmetic in order to improve the lag of control system and practice application proves that this new arithmetic is effective and improves the precision of coiling temperature control.(5)Since the online operation, the laminar process automation cooling system has been running stably with a high precision of coiling temperature control. Qualities and performances of products are improved significantly.