[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 use of UAV operator/servo amplifiers has proven to be an effective solution for ensuring stable operation and high productivity in blast furnace production.
[Keywords] 450m³ blast furnace, top pressure control, hot air temperature control
Project Overview
A 450m³ blast furnace at a steel plant was constructed in October 2005 and started iron production in June 2006. It has an annual iron output of 450,000 tons and a utilization factor of 3.0. After evaluating the overall cost-effectiveness of the system, the basic automation control system for the blast furnace and hot blast stove was designed using Schneider’s QUANTUM series PLCs. For the main instruments, the Xiamen AI-708J operator/servo amplifier with dual functionality was selected.
Control Process Requirements
Top Pressure Control: Maintaining stable top pressure is crucial for the smooth operation of the blast furnace. A stable top pressure ensures uniform gas flow and enhances the efficiency of the blast. During operations, the position of the top pressure regulating valve must be adjusted regularly to keep the pressure steady, avoiding fluctuations that could disrupt the furnace condition. The target top pressure for the 450m³ blast furnace is typically maintained at 90 ± 5 kPa.
Selection: The top pressure regulating valve is one of the most critical components. Due to frequent adjustments and high pipeline pressure, it requires precise control. Usually, three valves are connected in parallel to form a valve group, allowing for flexible and accurate regulation.
Control Mode: Two valves are manually opened to a fixed angle, while the third is automatically controlled. The control signal path is: PLC-AO output module → 4–20 mA signal → AI-708J → regulating valve. The process diagram is shown in Figure 1.
Hot Air Temperature Control: By adjusting the mixing valve, the correct amount of cold air is introduced into the hot air duct, keeping the hot air temperature within 1100 ± 20°C before it enters the blast furnace. There are 28 vents distributing the hot air.
Selection: An electric continuous control valve with 220VAC power supply is used.
Control Method: Automatic control is essential due to frequent adjustments. The signal path is similar to the top pressure control: PLC-AO output module → 4–20 mA signal → AI-708J → regulating valve. A single-loop PID control strategy is commonly applied.
Control Design
The AI-708J operator features several advantages:
(1) It integrates a handheld communicator and servo amplifier, ensuring compatibility with the PLC system.
(2) It supports automatic two-way switching between manual and automatic modes, enhancing stability and simplifying PLC programming.
(3) It offers a clear panel display and rich functions.
(4) It uses a modular design with multiple signal connection options.
(5) It provides reliable and stable operation.
(6) It meets electromagnetic compatibility (EMC) standards.
(7) It includes a parameter lock function, which prevents accidental modifications to critical parameters, improving safety and efficiency.
(8) It is user-friendly and well-documented, making it easy for operators to use.
Electrical wiring diagram of the PLC, electric control valve, and AI-708J operator/servo amplifier is shown in Figure 2.
Application Notes
1. A main image of the blast furnace production is shown in Figure 3.
2. The blast furnace uses four AI-708J units, including three for top pressure control and one for hot air temperature control.
3. Operation instructions for top pressure and hot air temperature control:
(1) When controlling via the upper computer, the operator should be set to "Automatic" mode using the A/M button. Otherwise, switch to "Manual" and adjust the valve using the up/down arrows.
(2) In automatic mode, set the desired top pressure or hot air temperature in the input box. The system will then perform PID control, comparing the feedback signal and dynamically adjusting the 4–20 mA output to the AI-708J, which controls the valve.
(3) In manual mode, switch the "Hand/Auto" button to "Manual" and enter the desired valve position in the corresponding input field. At this point, the PLC's PID program stops, and the 4–20 mA signal is sent directly to the valve.
After the blast furnace was put into production, the automated control system provided excellent protection and met all process requirements. The stable and reliable performance of the AI-708J operator/servo amplifier ensured consistent control of key parameters, enabling the blast furnace to reach its design efficiency within 15 days. The utilization coefficient reached 3.0, successfully meeting the project objectives.
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