Temperature Intelligent Control System of Large-Scale Standing Quench Furnace

Considering some characteristics of large-scale standing quench furnace, such as great heat inertia, evident time lag, strong coupling influence, hard to establish exact mathematical models of plant and etc, an artificial intelligent fuzzy control algorithm is put forward in this paper. Through adjusting the on-off ratio of electric heating elements, the temperature in furnace is controlled accurately. This paper describes structure and qualities of the large-scale standing quench furnace briefly, introduces constitution of control system, and expounds principle and implementation of intelligent control algorithm. The applied results prove that the intelligent control system can completely satisfy the technological requirements. Namely, it can realize fast increasing temperature with a little overshoot, exact holding temperature, and well-distributed temperature in quench furnace. It has raised the output and quality of aluminum material, and brought the outstanding economic and social benefits. A large-scale standing QF is the important device for producing high intensive aluminum alloy materials. The height is 31.64 m and the outer diameter is 2.8 m, the section view of the furnace is shown as Fig.1. The furnace is composed of heating room and working room. It's filled with silicate cotton between heating room and furnace wall. The working room is made of stainless steel. Furnace temperature is adjusted by changing the power of electric heating elements, which are firmly adhered to the inner wall of heating room. The furnace is fallen into 11 heating areas from top to bottom. Each area's temperature is measured by a thermocouple. Workpieces are hung up in the center of the working room. The roof, middle, bottom temperatures of working room are measured respectively by seven thermocouples. In order to let the temperature even, two powerful ventilators are placed at the bottom of furnace to force air circulating between heating room and working room and to increase heat exchanging speed in furnace. According to production technology, the heating process may be regarded as two stages, i.e., temperature- increasing stage and temperature-holding stage. During the former stage, the admitted maximum overshoot is 10 °C. During the temperature-holding stage, the required control precision of temperature is ±3 °C. Because the main working mode is heat convection, there are many problems, such as great heat inertia, evident time lag and strong temperature coupling among heating areas, furthermore, it's difficult to establish the mathematical model of temperature field in furnace. In order to make temperature even in furnace and realize exact control of temperature, a control algorithm that can synthetically consider above various factors is to be studied. Furnace ectrical ating urface Working room's wall Workpiece's surface