[Abstract] This paper discusses the application of Yudian products in the automation system of a 450m³ blast furnace, covering aspects such as project overview, control process requirements, system design, practical implementation, and operational performance. The results demonstrate that the UAV operator/servo amplifier significantly enhances the stability and efficiency of blast furnace operations, ensuring smooth production and high output.
[Keywords] 450m³ Blast Furnace, Top Pressure Control, Hot Air Temperature Control
Project Overview
A 450m³ blast furnace at a steel mill started construction in October 2005 and began producing iron officially by the end of June 2006. It has an annual iron output of 450,000 tons with a utilization factor of 3.0. After a thorough technical evaluation, the basic automation system for the blast furnace and hot stove was equipped with Schneider’s QUANTUM series PLCs. For the main instrumentation, the Xiamen AI-708J operator/servo amplifier was selected due to its dual-function capability, offering both manual and automatic control features.
Control Process Requirements
Top Pressure Control: Maintaining stable top pressure is crucial for efficient blast furnace operation. Fluctuations can disrupt gas flow and affect the overall process. To ensure stability, the top pressure is kept around 90 ± 5 kPa. The regulating valve is typically controlled using three parallel valves, with two manually adjusted and one automatically controlled. The signal path includes PLC-AO output, 4–20 mA signal, AI-708J, and finally the control valve.
Hot Air Temperature Control: The hot air temperature must be maintained within 1100 ± 20°C. This is achieved by adjusting the mixing valve to regulate the amount of cold air introduced into the hot air duct. A 220VAC electric control valve is used, and the control system employs a single-loop PID algorithm. The signal path follows the same pattern: PLC-AO output – 4–20 mA signal – AI-708J – control valve.
Control Design
The AI-708J operator/servo amplifier offers several advantages, including integrated handheld communicator and servo amplifier functions, seamless manual-to-automatic switching, rich functionality, modular design, and strong anti-interference capabilities. It also allows for parameter locking, which prevents accidental changes to critical settings. This feature is especially appreciated by on-site operators who frequently need to adjust parameters without disrupting the system.
Electrical Wiring Diagram
The wiring diagram between the PLC, electric control valve, and AI-708J operator/servo amplifier is illustrated in Figure 2. This setup ensures reliable communication and precise control over the blast furnace's key parameters.
Application Notes
1. The main production image of the blast furnace is shown in Figure 3.
2. Four sets of AI-708J units are used in this system, with three dedicated to top pressure control and one for hot air temperature control.
3. Operation Instructions:
- When controlling via the upper computer, the operator must be set to "Auto" mode using the A/M button. Otherwise, it should be in "Manual" mode, where the valve opening is adjusted using the up/down arrows.
- In automatic mode, the "Hand/Auto Switch" should be set to "Auto," and the desired top pressure or hot air temperature should be entered. The system then performs PID control based on feedback signals.
- In manual mode, the "Hand/Auto Switch" is set to "Manual," and the valve position is manually inputted. At this point, the PID program stops, and the 4–20 mA signal is directly sent to the control valve.
After being put into production, the automated control system provided excellent protection and met all the process requirements. The reliable performance of the AI-708J ensured stable control of top pressure and hot air temperature, allowing the blast furnace to reach its designed production capacity within 15 days. The utilization coefficient reached 3.0, successfully achieving the intended design goals.
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