In current blast furnace iron production in China, tap hole drilling machines generally use hydraulic control rather than electrical control. This choice is not accidental but based on the stringent requirements of the blast furnace operating environment, the special functional needs of the equipment, and the unparalleled advantages of hydraulic control technology. The following will provide a detailed explanation of the underlying reasons and the prominent advantages of hydraulic control over electrical control.
I. The Harsh Requirements of the Blast Furnace Operating Environment for Control Methods
Blast furnace ironmaking is a highly challenging production process characterized by high temperatures, heavy loads, high dust levels, and complex and variable operating conditions. During operation, the tap hole drilling machine must withstand temperatures of 1,400–1,600°C from molten iron, Withstand hundreds of tons of impact force and continuous vibration during the iron ore opening process, while maintaining stable operation in an environment where dust concentration often exceeds 50 mg/m³. Under such harsh conditions, the control system must possess robust power output, high stability, and reliability to ensure smooth blast furnace tapping operations and prevent production accidents or equipment damage caused by control failures.
II. Comprehensive Comparison and Analysis of Hydraulic and Electric Control Systems
(1) Power Output Capacity: The Strong Advantage of Hydraulics
Hydraulic control converts the mechanical energy of an electric motor into hydraulic energy via a hydraulic pump, which is then converted back into mechanical energy by a hydraulic cylinder or hydraulic motor. This system can generate a powerful thrust of 300–800 tons, with flexible adjustment capabilities and a power response time of ≤0.1 seconds, enabling instantaneous bursts of force.
In contrast, electric control primarily relies on electric motors for power. Despite continuous advancements in motor technology, under the same volume and power conditions, the torque and thrust of electric motors typically range from 50 to 150 tons, with peak output limited and a power response time of ≥0.5 seconds, significantly influenced by motor inertia. A certain electric iron mouth opening device requires 5 minutes to complete the iron mouth opening process, with a success rate of only 70%, failing to meet the demand for instantaneous bursts of powerful force during iron mouth opening.
(2) Stability and Reliability: Hydraulic Stability Assurance
Hydraulic systems offer excellent cushioning and vibration-damping performance. During iron opening, when encountering changes in the internal structure of the iron opening or sudden increases in resistance, the compressibility of hydraulic oil and the regulating function of hydraulic valves can automatically adjust the output force, absorbing over 60% of the impact energy, ensuring smooth equipment operation, and effectively preventing equipment damage or control failure caused by excessive impact. Additionally, hydraulic components are connected via fully enclosed piping, achieving an IP68 protection rating, effectively isolating dust, iron filings, and other contaminants. Even in the harsh environment of a blast furnace, the mean time between failures exceeds 8,000 hours.
Electronic components in electrical control equipment are highly sensitive to environmental conditions. In high-temperature environments above 80°C, the failure rate of PLC modules increases by threefold; in high-dust environments, dust entering the motor reduces its heat dissipation efficiency by 40%, affecting normal operation; high-temperature magnetic fields can also cause encoder signal errors exceeding 10%, leading to unstable signal transmission. These factors significantly reduce the reliability of electrical control equipment, increasing maintenance costs and downtime.
(3) Control Precision and Flexibility: Hydraulic Precision and Flexibility
Hydraulic control can achieve precise flow, pressure, and direction control through various hydraulic valves, enabling high-precision pressure regulation at the 0.5% level and supporting “S-type” speed curve control. During the initial stage of iron mouth opening, the hydraulic system pressure can be adjusted to slowly drill with minimal force, protecting the iron mouth equipment; as the iron water channel is approached, the pressure is increased to rapidly open the iron mouth. For example, after adopting hydraulic control, Lian Steel improved the verticality of the iron mouth channel to 98.7%, significantly enhancing the quality and efficiency of iron mouth opening and extending the service life of the iron mouth.
Although electric control theoretically offers higher precision, in practical applications, electric motors have inertia during startup, shutdown, and speed adjustment, resulting in slow response times and difficulty adapting to the complex and variable conditions during iron mouth opening. Additionally, electric control equipment has a speed adjustment range of only 1:100, unable to provide the wide-range power output adjustment that hydraulic control can offer based on different requirements.
(4) Maintenance and Cost: Hydraulic Economic Advantages
Hydraulic system maintenance is relatively simple, primarily focusing on hydraulic oil replacement and hydraulic component seal inspections. As long as qualified hydraulic oil is replaced regularly and the system is kept clean and sealed, hydraulic components have a longer service life. Additionally, hydraulic components have a high degree of standardization, making spare parts easily obtainable in the market and repairs convenient and swift. Based on a 5-year cycle calculation, the annual maintenance costs are relatively low.
Once electronic components in electrical control equipment fail, repairs are challenging and require specialized technicians and diagnostic equipment for fault diagnosis and repair. Some high-end electronic components are expensive, resulting in high replacement costs. Furthermore, due to frequent failures in the harsh environment of blast furnaces, maintenance frequency increases, leading to significantly higher overall maintenance costs compared to hydraulic control equipment.
(5) Actual application in the global market: widespread recognition of hydraulics
In the domestic market, large and medium-sized blast furnaces such as Baosteel, Shougang, and Wuhan Iron & Steel all widely adopt fully hydraulic tap hole drilling machines.
In the international market, mainstream blast furnace equipment suppliers in Europe, Asia, and North America all use hydraulic control as their core technology. Hydraulic tap hole drilling machines account for 75% of the European market share, and fully hydraulic equipment accounts for as much as 92% of the market share in South Korea.
III. SummaryIn summary, whether in the Chinese market or the international market, the adoption of hydraulic control for blast furnace tap hole drilling machines is the optimal choice after fully considering the special nature of the blast furnace operating environment and equipment functional requirements. Hydraulic control offers significant advantages over electrical control in terms of power output, stability and reliability, control precision and flexibility, as well as maintenance costs. It can better adapt to the complex and harsh production conditions of blast furnace ironmaking, ensuring the efficient and stable operation of the tap hole drilling machine, and significantly enhancing the safety and economic benefits of blast furnace production.
We hope the above content provides you with a clearer understanding of why hydraulic control is adopted for blast furnace tap hole drilling machines. If you have any further questions or require additional information, please feel free to contact us at any time!
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