Silicon-iron is a compound that is widely used as a deoxidizer and alloying agent in industrial processes such as steelmaking and casting, playing an essential role in industrial production. The smelting of silicon-iron is carried out in an electric furnace using coke, steel scrap, and quartz (or silica) as raw materials. The production of silicon-iron consumes large amounts of energy and generates significant dust emissions. To prevent environmental pollution caused by dust and improve energy efficiency, high-quality high-voltage variable-frequency drives are indispensable driving equipment for electric-furnace dust collectors.
STEP continues to support ferroalloy manufacturers in their upgrade and transformation efforts.
A ferroalloy plant in Lanzhou, Gansu Province, is a key player in local silicon-iron smelting and has established a long-term cooperative relationship with STEP. To address the contradiction of insufficient production capacity, the company has upgraded and renovated its silicon-iron electric furnace system. With the goal of achieving comprehensive improvements in one step, enhancing dust removal efficiency has also been given top priority.
After careful evaluation, the company decided to replace the fan, motor, and drive frequency converter in its dust collector. Based on the excellent performance of previous products, the customer chose STEP frequency converters without any hesitation to replace their existing brand’s converters. The company believes that, after more than a decade of comprehensive comparisons—including production use and after-sales service—STEP frequency converters offer greater operational stability, lower failure rates, and superior service.
Now, let’s take a look at how the STEP frequency converter performed specifically in this upgrade!
Schematic Diagram of the Process Flow for a Large-Scale Reverse-Blow Baghouse Dust Collector
Reverse-Blow Baghouse Dust Collector Process Flow
The silicon-iron electric furnace production process consists of several stages: charging materials, applying power to melt the charge, blowing oxygen, reduction, and slag removal to remove iron. The entire smelting cycle of the electric furnace lasts approximately 90 minutes, with the power-on melting and oxygen-blowing stages accounting for about 60% of the total process time. During these stages, high-temperature dust-laden flue gases are cooled by water-cooled dust collectors and then passed through reverse-air bag filters for purification before being discharged into the atmosphere. Throughout the entire dust removal process, the reverse-air blower and the dust removal fan are high-energy-consuming devices. By using frequency converters to adjust their operating frequencies according to the requirements of the production process, energy efficiency can be significantly improved.
Inverter System Configuration
In this project’s upgraded dust removal system, the reverse-blow fan is equipped with a new Shihua AS450 series vector-type low-voltage frequency converter, with a rated power of 280 kW. The dust removal fan, meanwhile, uses an AS800 series 1250 kW high-voltage frequency converter. Previously, four Shihua AS800 series high-voltage frequency converters had already been successfully deployed in earlier upgrades carried out by this manufacturer.
Dust Removal High-Voltage Inverter in Operation
STEP AS800 High-Voltage Variable Frequency Drive—Driving Advantages
· Power factor of 0.95 or higher, with no harmonic interference to the power grid.
· The entire machine boasts high efficiency, with a full-load operating efficiency exceeding 96%, thereby enhancing energy utilization.
· The frequency converter-driven system allows for free speed adjustment according to process requirements, effectively eliminating energy waste.
· Equipped with a soft-start function for fans and pumps, enabling smooth restarts of fan and pump loads without interrupting their operation.
· Variable-frequency, disturbance-free synchronous switching function enables line-frequency startup for high-power fan and pump loads.
· Power-off endurance and power-off restart functionality ensure normal operation of the device even in the event of a momentary power outage in the grid.
· Supports unit bypass functionality; when a single unit fails, it automatically switches to bypass operation, ensuring continuous equipment operation.
· Custom VF curve function to meet the starting requirements of various fan loads.
· Multiple control methods available for flexible selection: panel, terminals, and various communication controls.
· Equipped with multiple power-frequency bypass systems, enabling frequency conversion switching according to customer process requirements.
· Comprehensive self-diagnosis and display function, supporting virtual oscilloscope and event log display.
· Variable-frequency speed control with a built-in PID closed-loop pressure control and process closed-loop control, ensuring stable voltage regulation and eliminating the need for valve adjustments.
· Variable-frequency speed control enables soft starting of the system, reduces startup impact, and extends the service life of equipment.
· Supports permanent magnet synchronous/externally excited synchronous motor drives without requiring hardware configuration changes.
· High-voltage cluster control system, supporting remote centralized monitoring and control.
