Abstract: This paper introduces the method for detecting material thickness in blast furnaces and the adjustment principle of frequency converters, as well as the structure and configuration of the control system based on the Proifbus-DP network. The PID control configuration method for the communication programming process between the Siemens S7-300 PLC and the frequency converter is briefly described.
Keywords : Profibus; Programmable Logic Controller; AC Frequency Converter; PID Control
Inverters are fundamental devices commonly used in AC speed control. Generally, a PIE (Portable Controller) is used as the controller, and the inverter as the controlled device. The operation involves using the PIE's digital I/O signals to control the inverter's start and stop via its terminals, and using analog I/O signals to control the inverter's operation and speed regulation. As inverter performance and functionality improve, control becomes increasingly complex, inevitably leading to increased wiring and unavoidable interference issues. With the expansion of modern factories and the application of fieldbuses, network-based remote control has become possible. PROFIBUS is currently a mainstream industrial communication network in Europe, offering advantages such as high communication speed, open protocols, and simple wiring. Data obtained through communication is unbiased and can be used as a basis for implementing closed-loop speed control using the PID algorithm of the PIE, effectively recording data for analysis.
1. Material thickness detection and analysis
In blast furnace ironmaking system engineering, the thickness of the material surface is a very critical parameter, and the detection of the material surface is of utmost importance. Assuming the material is located in a relatively small blast furnace, due to the high temperature of the material surface and the unevenness of the material surface, the detectable space is small. Therefore, a high-temperature resistant heavy hammer is used to directly contact the material surface. The hammer is pulled by a steel wire rope, and the other end of the steel wire rope is fixed to a roller through a pulley. The roller is driven by a motor through a gearbox. Then, the thickness of the material surface is determined by calculating the code number on the encoder mounted on the coaxial with the roller. The problem to be solved in the material surface detection is to make the hammer descend slowly during the descent process, stop automatically after hitting the material surface, and then descend with the material surface. It is divided into two processes: (1) the hammer descent process, and (2) the hammer descent process with the material surface. When manufacturing the hammer, it is specially made into a shape with a low center of gravity, so that in the second process, the hammer can descend with the material surface by gravity without the need for control. Therefore, the problem is concentrated on the only process of the hammer descent.
For details, please click:
Application of Profibus-based frequency converters in blast furnace material thickness detection
