Application of FD5000 in Driving Synchronous Fans for Steel Smelting
Sintering is a primary method for iron ore agglomeration. The straight-line suction sintering machine is widely used to produce sintered ore. The main sintering exhaust fan acts as a core component, directly impacting the machine's output, product quality, and energy consumption. This solution introduces a novel Sintering Heat Recovery Three-unit (SHRT) system. It arranges the sintering waste heat turbine, the main exhaust fan, and a synchronous motor coaxially in series. The system utilizes the FD5000 series high-voltage frequency converter to drive the synchronous motor.
Implementation Plan
The induced draft fan mixes flue gas from No.1 and No.2 chimneys and directs it into a high-efficiency waste heat boiler. The boiler system generates superheated steam and low-pressure saturated steam, which then power the steam turbine for electricity generation. However, the exhaust gas temperature from the induced draft fan remains above 150°C, presenting an opportunity for further heat recovery. The sintering waste heat power generation system includes a circulation fan. This fan diverts a portion of the exhaust gas; one part discharges into the atmosphere via a three-way damper valve, while the other part pressurizes and returns to the annular cooler's air plenum. This process both cools the sintered ore and increases the exhaust gas temperature from the annular cooler.
Sintering waste heat power generation converts waste heat from sintered exhaust gas into electrical energy. This technology produces no additional waste gas, slag, or dust emissions. It significantly improves the energy efficiency of the sintering process. On average, recovering waste heat from each ton of sintered ore can generate 20 kWh of electricity. This reduces the comprehensive energy consumption per ton of steel by approximately 8 kg of standard coal, helping steel companies achieve energy saving and emission reduction goals.
The motor operates at 10 kV with a power of 4500 kW. The system uses the FD5000-10-4500F-1A frequency converter in a one-on-one automatic bypass configuration. A coordination control cabinet manages the operation of the frequency conversion cabinet. If the frequency converter fails, the system quickly transfers the load to the bypass cabinet. This switch enables direct line-frequency operation, ensuring continuous sintering production without interruption.
Application Advantages
1.Significant Energy Savings: This benefit is the most direct. Energy consumption for fan and pump equipment correlates to the cube of the rotational speed. Adjusting the air volume via variable frequency speed control, rather than simple "throttling," achieves substantial electricity savings.
2.Excellent Speed Regulation and Control: High-voltage variable frequency drive technology delivers high output power and creates minimal harmonic pollution to the power grid.
3.Smooth Startup and Equipment Protection: Frequency conversion enables a gentle starting current. This approach effectively avoids the impact of direct line-frequency starting on both the motor and the power grid, thereby extending equipment service life.
4.Improved Process Control: It allows more precise and flexible adjustment of process parameters like air volume and negative pressure. This enhanced control helps stabilize the sintering process and improves product quality.
