The Application Of WIN-HV Inverter In Iron And Steel Industry

The Application of WIN-HV Inverter in Iron and Steel Industry

Abstract:

This essay explains the application of WINNER-branded medium voltage inverter (hereafter referred as WIN-HV inverter) manufactured by Shenzhen Winner S&T Co Ltd in Guangyao Steel Co Ltd. Field operation shows WIN-HV inverter has been bringing prominent economic benefits to the steel producer after it equips its dust exhaust fan with the machine.

Key word:

WIN-HV inverter, dust exhaust fan, energy-saving reformation

I Prolegomena

China became the largest country in the world by steel output in 2006. However, the problem of high energy consumption still lingers that strictly hampers the development of the country’s steel industry. Statistics indicate the steel industry accounts for nearly 15% of China’s total energy consumption, ranking the top 3 along with the electricity industry and chemical industry. Energy saving tops the Chinese government’s and also the steel industry’s agenda.

II Introduction of Guangyao Steel

Guangyao Steel is engaged in pig iron smelting and foundry, mine powder agglomeration, and iron powder washing. The company has recently developed a steel-making project, with an aim to enhance its competitiveness and reduce energy consumption. After repeated investigation, Guangyao Steel picked WIN-HV inverter as the energy saving equipment to drive its dust exhaust fan in the steel-making project.

As is known to all, each blast furnace has a steel-converting mouth and a steel-tapping mouth. When the blast furnace converts or taps liquid steel, a large amount of fume arises as the hot liquid steel makes intense chemical reaction with the air. That is harmful to the operators and also causes huge pollution to the environment. In order to eliminate pollution and ameliorate working environment, it is necessary to conduct dust-exhaust reconstruction on the steel-converting and steel-tapping sections. In Guangyao, it commonly takes about 100 minutes to produce a barrel of steel – 20 minutes of feeding, 60 minutes of smelting and 20 minutes of tapping. The whole process can be controlled automatically by the oxygen lance, or manually controlled at the location of the oxygen lance.

In view of production requirements, the dust exhaust fan need produce two-type wind volume, so it is supposed to have two-step speed control option -high speed and low speed – low speed for feeding and tapping and high speed for smelting. Meanwhile, the acceleration time must be as short as possible, or it will tamper dust-exhaust efficiency. The acceleration time from low speed to high speed must be not more than 40s.

III Scheme Designing

According to the local conditions and qualifications, the reconstruction scheme is as following:

  • l Simplify the control logic --directly control the speed of the inverter according to the on/off condition of the steel-converting mouth and steel-tapping mouth.
  • l Preset the inverter with two speed steps, and automatically adjust the motor speed according to different wind volume requirements.
  • l Preset time and speed on the user interface of the inverter through the advanced programmable function of built-in PLC. Please refer to the table below

Rated power

800kW

Rated power

800kW

Rated voltage

10000V

Rated voltage

10000V

Rated frequency

50Hz

Rated frequency

50Hz

Rated current

55.4A

Rated current

58A

the reconstructed electrical system as following:

IV Efficiency

  • Prolong the service life of the motor and the fan.
    The dust exhaust fan is centrifugal-type, with long starting time and huge starting current (about 6~8 times of the rated current), which brings huge mechanical wear abrasion to the motor and fan, and accordingly decrease their service life. In contrast, soft starting and soft braking can be realized when the WIN-HV inverter is installed, eliminating surge current and wear abrasion to the motor and fan.
  • Prevent the valve and the fan impeller from damage.
    When the WIN-HV inverter is installed, the fan runs at a speed 150 r/Min lower than the rated speed, steeply decreasing vibration of the fan and wear abrasion chance of the fan impeller. Maintenance and repair cost will be cut a lot.
  • Easy to achieve dust exhaust control system automatization.
    The wind volume of the dust exhaust system always fluctuates according to different production requirement. In the previous valve regulation mode, automatic control system is vulnerable to be out of efficiency because valve wear abrasion gradually results in valve characteristics changes. While the inverter can guarantee the fan to run with a linearity accuracy of 0.1~0.01HZ, creating eximious conditions for dust exhaust control system automatization.
  • Ameliorate production technics.
    WIN-HV inverter help realize smooth and stable wind volume regulation, relieve the labor intensity, and enhance efficiency.

Successful application cases have proved Winner’s R&D and production strength. WINNER is indeed one of China’s top 10 brands of medium-voltage inverter. Compared with other medium-voltage inverters, WINNER-branded medium-voltage inverter has several unique predominances as follows:

1. Less harmonic content of input /output current and input /output voltage, meeting the standard of IEC61800-4:2002; the input power factor is high, and can reach 0.97 in the speed adjustment range; less noise and heat; it won’t trigger motor pulsation and can drive various kinds of motors; no need to install noise filter and power factor compensation; harmonic distortion rate of current on the line side is within 1.90%

2. WIN-HV inverter is of voltage-source type frequency inverter, with a lot of capacitors and nice endurance to grid fluctuation; the inverter can maintain normal operation at the voltage width of -20% ≤ rated voltage ≤ +15%.

3. WIN-HV inverter adopts special air duct design, which makes daily inspection more convenient. Users can conduct daily inspection anytime even when the inverter is in normal running.

4. The frequency conversion efficiency of WIN-HV inverter hits 98.5%, and the system efficiency, which maintains the same within the speed adjustment range, exceeds 96%.

5. All the WINNER-branded high power high-voltage inverters (power≥2500kW) adopt the unique airtight recycled-water cooling technology; nice heat dissipation potential; no need to add the wind exhaust duct, save cost and easy for maintenance and repair.

6. WIN-HV inverter adopts unique structure: the control cabinet lies at the low potential terminal, suppressing electromagnetic interference and enhancing the inverter’s reliability; meanwhile, users can inspect anytime the operating conditions of the inverter system.

7. The drive circuit of WIN-HV inverter, developed all by Shenzhen Winner itself, guarantees stability and reliability of the inverter. Adding to the unique low inductance bus structure, it enables the company to have manufactured an 8000kW high-voltage inverter-the first one of its kind in China.

V Direct Economic Benefits

WIN-HV inverter has won Guangyao Steel’s high praise for its reliability and stability since it started operation in 2006. It is estimated by the engineers of Guangyao that the two sets of WIN-HV inverters can bring more than RMB0.4 million profits per year for the steel maker.

Please refer to the motor & inverter parameter as following:

Motor Parameter

Inverter Parameter

Rated power

800KW

Rated power

800KW

Rated voltage

10000V

Rated voltage

10000V

Rated frequency

50Hz

Rated frequency

50Hz

Rated current

55.4A

Rated current

58A

Rated speed

2981r/Min

Running current
(at high speed)

 

31A

COSΦ

0.88

Running current
(at high speed)t

 

14A

 

 

High speed

2100 /Min

 

 

Low speed

1200r/Min

VI Conclusion

Three years have gone by since Shenzhen Winner S&T Co entered the medium-voltage inverter production field. In the past three years, Shenzhen Winner has created a succession of shiny achievements, positioning itself China’s leading inverter manufacturer. Its products, under the brand of “WINNER”, won the title of “one of China’s top 10 brands of medium-voltage inverter in 2007” and “one of the top 10 satisfactory brands in 2007” by Electric Age. The application case hereinbefore indicates that based on its prominent technology, WIN-HV inverter is no doubt the best energy saving choice for medium-voltage motor speed regulation in the iron and steel industry.