Electrostatic dust removal is a process that involves four main stages: gas ionization, dust charging, collection of charged particles, and cleaning. The core principle involves applying a high-voltage direct current to create an uneven electric field between the anode plate and cathode wire. As smoke passes through this field, it becomes ionized by the strong electric force, producing positive ions and free electrons. Dust particles in the smoke interact with these electrons, becoming charged and then attracted to the grounded anode plate. Once collected, the dust is removed via a cleaning system. For optimal performance, the electrostatic precipitator requires a suitable power supply. Common types include industrial frequency SCR power supplies and high-frequency switching power supplies.
This article analyzes and compares the technical specifications and economic benefits of traditional industrial frequency power supplies versus high-frequency switching power supplies used in electrostatic precipitators. It recommends adopting high-frequency switching power supplies to meet increasingly strict environmental regulations and to provide significant economic benefits for power generation companies.
**2. Industrial Frequency SCR Power Supply for Electrostatic Precipitators**
Electrostatic precipitators using industrial frequency SCR power supplies may experience reduced efficiency when dealing with high-resistance dust or anti-corona phenomena. This often leads to failure in meeting original design criteria and environmental emission standards.
Industrial frequency power supplies have several disadvantages:
1. Low working frequency results in low conversion efficiency (typically below 70%), leading to high energy consumption.
2. Input is a two-phase 380V AC power supply, which causes a low power factor (often less than 0.7), leading to imbalanced distribution systems.
3. Large output ripple results in lower average voltage compared to peak voltage, reducing corona voltage and making operation difficult under high-dust conditions.
4. Low operating frequency makes transformers and filters bulky and heavy.
5. The power control cabinet and transformer are separated, increasing space usage, cable waste, and infrastructure costs.
**3. High-Frequency Power Supply for Electrostatic Dust Removal**
High-frequency power supplies convert three-phase AC into DC, then invert it into high-frequency AC before boosting and rectifying it to deliver high-frequency ripple current to the precipitator. Operating at around 40kHz, they offer improved flexibility and control.
The high-frequency power supply uses narrow pulses with adjustable amplitude, width, and frequency, allowing for various voltage waveforms tailored to the precipitator’s operating conditions. This improves dust removal efficiency and saves energy.
It consists of three parts: inverter, transformer, and controller. The full-bridge inverter converts DC to high-frequency AC, while the high-frequency transformer and rectifier boost and stabilize the voltage for the precipitator.
High-frequency power supplies are more compact, efficient, and environmentally friendly, with balanced input and minimal grid pollution. They also offer better electromagnetic compatibility and are highly integrated, making installation easier and cost-effective.
**4. Technical Specifications and Application Performance Comparison**
High-frequency power supplies outperform traditional industrial frequency power supplies in multiple areas:
1. Conversion efficiency can exceed 90%, compared to 70% for industrial frequency.
2. Power factor is above 0.9, whereas industrial frequency is typically below 0.7.
3. Balanced three-phase input reduces grid pollution and eliminates phase loss.
4. High-frequency power increases corona voltage and current, improving dust charging ability.
5. Spark detection is faster (less than 25μs vs. 10,000μs), reducing energy loss and accelerating recovery.
6. Smaller size and higher integration reduce space, cabling, and installation costs.
**5. Engineering Operation Parameter Comparison**
In recent years, high-frequency power supplies have been widely adopted in power plant upgrades. For example, a 2×300MW unit's No. 2 boiler was upgraded from a three-field to a four-field system, achieving a dust removal efficiency of 99.86%. Testing showed that high-frequency power increased electric field strength, reduced rear field load, and improved overall efficiency.
Energy savings calculations showed that high-frequency power saved about 20.4% in energy, and after optimization, the savings reached up to 32.5%.
**6. Investment Estimation and Economic Analysis**
Although high-frequency power supplies are initially more expensive, they reduce other equipment costs and save on cabling and installation. For instance, one project saw a 1.32 million yuan increase in comprehensive engineering costs. However, annual energy savings amounted to 2.34 million yuan, allowing the investment to be recouped within six months.
**7. Conclusion**
After years of development and field application, high-frequency power technology has proven to be efficient and reliable. While initial investment is higher, its energy-saving performance is remarkable, offering excellent cost-effectiveness and aligning with national energy conservation and emission reduction goals. Therefore, high-frequency power technology is strongly recommended.
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