| A coke oven represents a kind of controlled object with a full spectrum of closely coupled factors, such as distributed parameters, no-linearity, time-dependent change and multi-variable features. Among them, the discharge header pressure and fan suction are key parameters, and also constitute strongly coupled variables with very close inter-relation, which are fulfilled by the way of regulating coal-feeding and the rate of primary air supply in practice. When several coke ovens are connected in parallel, there are many external disturbance factors, as well as complex coupling relations, so the discharge header pressure system of coke oven is a complex multivariable control system and there is no mathematical model up to now. The above circumstances will create some difficulties for the design of a discharge header pressure of coke oven control system, whose difficulties make it hard to realize an accurate control.In this paper, after comparing the difference of some kinds of decoupling control method, aiming at the feature of the coke oven pressure system and based on the coupling phenomena caused by the fluctuate between border upon channels, using the theory of feedforward and thinking about the influence between the fan suction and the discharge header pressure, a kind method of fuzzy feedforward is presented and used to control the discharge header pressure. In this method, the system features, such as no-linearity, no-easy constructing model and serious coupling are fully considered. The control effect manifests the validity of the decoupling methods presented in this paper. It can solve many questions in the operation of coke oven.An engineer case is introduced, which is about "The Reconstruction of High Voltage Fan's Speed-adjusting by Frequency Conversion and the Design of PLC(programmable logic controller) Control System in Shui Cheng Iron and Steel Company". In this project, an advanced controlling technology ,based on the method in this paper, is used to realize the closed loop control of discharge header pressure of two coke ovens. Based on the experience of regulating frequency according to different valve's angle, a reasonable controlling tactic is proposed . When the situation changes to a small degree, electromotor makes fan running at a constant rate; when the situation changes to the limiting range, the discharge header pressure is automatically adjusted by the rate of fan.The style of PLC is SIEMENS's S7-300, which is composed of the controlling system of coke oven and fan.The result of practical control shows that the pressure control system has better static and dynamic characteristics. This system can decrease the coupling influence of controlled objects, and has good anti-interference performance, so it can completely satisfy the need of coking craftwork. Additional, the algorithm is so simple that it can be realized by PLC and uses in practical production of coke oven process successfully.
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