INVT GD5000 series MVD used for Kiln ID fan in Vietnam

Abstract: In cement industry, the kiln ID fan demand has shifted from simple exhaust capacity to precise pressure control, high energy efficiency, and long-term reliable operation. This article showed the INVT GD5000 series MVD provides fast response, significant energy savings, reduced mechanical stress for this application.

Keywords: Cement, Kiln ID Fan, GD5000 MVD

I. Project background

The kiln ID fan is the core driving equipment of the cement kiln exhaust system. It maintains stable negative pressure throughout the kiln, calciner, and preheater, ensuring stable process operation, efficient combustion, and reliable downstream dust collection.

The project is located in a cement plant in Vietnam. It is an old equipment renovation project. The old system has many challenges:

• High-energy-consuming control methods: Regulating airflow through fan inlet dampers or hydraulic couplings leads to significant energy waste due to throttling resistance or slip losses, resulting in low efficiency.

• Challenges of harsh operating conditions: The equipment needs to withstand wear and corrosion caused by high temperatures and high dust concentrations (dust content can reach 100 g/m³), placing extremely high demands on the fan materials, sealing, and cooling systems.

• Starting impact and maintenance issues: Direct starting at power frequency or traditional starting methods cause significant impact on the power grid and mechanical components, leading to high equipment failure rates and high maintenance costs.

II. Customer requirements

The kiln ID fan is the "lungs and heart" of the entire cement kiln system, and the current demands for it are concentrated in the following aspects:

• Stable negative pressure control (the most critical requirement): The control objective has upgraded from "simply being able to extract air" to "precise and controllable."

• Significant pressure to reduce energy consumption (the most realistic current need): The kiln ID fan is one of the largest single power-consuming pieces of equipment in a cement plant. In the context of dual control of energy consumption and carbon reduction, a 5% reduction represents enormous value.

• Adaptability to extremely wide operating condition variations: The actual operating conditions of the kiln ID fan vary greatly, requiring the fan to have a wide adjustment range and fast response capabilities.

• High reliability & low unplanned downtime: High temperature, high dust, and continuous operation. Unplanned kiln shutdowns result in huge losses, requiring minimal maintenance periods and necessitating fault prediction and protection capabilities.

III. INVT Solution

In the factory, the kiln ID fan motor is suppled by one Chinese company in 2015, 4200kW, 6kV, 50Hz, 477A, 2758rpm.

Motor and fan photo

Accroding to the motor rating and customer demand, the configuration is as below table:

And the system schematic diagram is as below:

Solution features

• Profibus-DP communication, fast communicate with DCS, realize speed control, save energy.

• Realize soft start, less shock, extend the mechanical system lifetime.

• IoT module, remote monitoring.

• Cabinet separately installed in different rooms, save cooling power.

• Multiple pulse rectifier, low harmonics, high efficiency.

• Support Vietnamese language.

Site photos:

The MVD cabinets are separately installed in two rooms to save the cooling power.

The transformer cabinet (normal room with fan)

The power unit and control cabinet (room with AC)

Control panel photo (IOT module at the top)

IV. Customer benifits

• Significant energy savings: Fan power consumption is proportional to the cube of the rotational speed. The MVD reduces the speed to meet the required airflow, avoiding energy losses caused by valve throttling. The payback period is typically 1-3 years.

• Greatly improved process control: The VFD can be seamlessly integrated with the DCS system to achieve closed-loop automatic control of air pressure and airflow, resulting in smoother kiln system operation, improved product quality, and increased system automation.

• Comprehensive protection of equipment and power grid: The soft start function eliminates large current surges, protecting the motor, fan, and power grid. Simultaneously, reduced speed operation significantly reduces wear on mechanical components such as bearings and blades, extending the overall equipment lifespan.

• Improved operating environment: VFD operation allows the fan inlet damper to be opened to its maximum, reducing airflow turbulence and throttling noise, and helping to solve duct vibration problems.

• IoT modules enable intelligent control and remote diagnostics: The MVD provides current, torque, and load trends via IoT, facilitating predictive maintenance and early fault warning.

V. Conclusion

This application case successfully addressed the core problems of high energy consumption, imprecise control, and frequent equipment maintenance faced by the kiln induced draft fan in actual operation. The retrofit yielded comprehensive and significant benefits, validating the critical value of INVT medium-voltage variable frequency technology in energy saving, efficiency improvement, and intelligent upgrading in the modern cement industry.