The Vekont VFD was utilized for controlling the vacuum pumps in a plastic packaging plant, resulting in a significant reduction in energy consumption through the implementation of variable-frequency technology to upgrade the vacuum pumps. A prominent manufacturer in China's food packaging industry, this large-scale plastic film production enterprise specializes in producing and heat-forming plastic films into various shapes for product packaging within the food and retail sectors. With a strong emphasis on energy conservation and environmental protection, the company has been actively striving to reduce energy consumption during its production processes.

1. There has been a significant reduction in energy consumption. One crucial aspect of energy saving in a plastic packaging plant is the vacuum pump system used for transporting plastic granules. The company made the decision to replace the previous 38 individual vacuum pumps with a vacuum pump system equipped with three pumps. Two of these pumps are driven by 22kW three-phase motors, while the other pump is driven by a Vekont inverter-driven motor. As a result, the original power supply to the vacuum pumps was reduced from 285kW to 66kW, and the average energy consumption decreased from 95kW to 35kW.

The factory operates continuously for 24 hours a day, throughout 361 days each year. The maximum workload of the vacuum pumps reaches approximately 15,000 kg/h of plastic granules and sometimes needs to be increased up to 2,000kg/h of plastic granules. Based on historical data, it can be estimated that around 8 to10 kg of plastic granules can be transported per cubic meter of gas. Therefore, it became evident that two vacuum-driven pumps were insufficient to meet processing capacities ranging from 16,000kg/h up to 20,000kg/h.

Each vacuum-driven pump has an ability to transport 1002m3/h of gas at apressure of 400MBR; however,the pressure generated by the inverter-driven pump is slightly lower at around 350MBR.The motor operates at 50Hz and 2,940r/min while the pump speed is lower at approximately 2,780r/min.

Thanks to dramatic reductions in enery consumption and motor speed control,the factory has managed to save 21%. The energy consumption per unit product has been reduced to 80% of what it was in 2018, and the effects of energy saving are quite evident. It is expected that the total investment for upgrading equipment will be recovered with in three years.
 

2. The use of interactive applications effectively reduces maintenance costs.

The vacuum pump station operates interactively, with the pumps being activated based on the required gas volume. The first pump to be activated is a variable-frequency-controlled pump, and if its operating frequency exceeds 56 Hz or remains above 56 Hz for more than 15 seconds, the second pump is directly started at rated voltage. Simultaneously, the operating speed of the variable-frequency-controlled pump is adjusted to match the gas demand. The third pump remains in standby mode. The variable-frequency pump operates within a range of 0 to 58 Hz, ensuring linear flow regulation in the pumping system.

By utilizing variable-frequency drives to change the speed and starting sequence of pumps, it ensures consistent load distribution and minimizes unnecessary mechanical stress on all three pumps, resulting in reduced equipment maintenance costs. Furthermore, long-term implementation of interactive methods also leads to energy savings. Although our company's variable-frequency drives are highly durable, spare parts are still provided by local agents as a precautionary measure. Additionally, employing variable-frequency technology helps reduce ambient temperature and noise levels.

3.Pump and fan applications macro is standard configuration
Similar to other variable-frequency drives available in the market, this drive comes equipped with a built-in software package that includes five application macros such as those specifically designed for pumps and fans usage scenarios. This particular macro can be utilized for driving one main variable-frequency pump along with up to four auxiliary pumps simultaneously.
The motor connects directly to this drive unit while allowing flexibility in altering starting sequences for auxiliary pumps through automatic switching functions provided by software controls combined with an external relay system.

4. Conclusion

The Vekont variable frequency drive has gained extensive utilization in the printing and packaging industry, thereby providing favorable conditions and technical means for its convenient application.