Shredders/Sugarcane feeders and millings are important equipment in sugar juice extraction. The method to measure sugar extraction efficiency is sugar extraction rate. Sugar extraction rate is the percentage of extracted sugar to the total sugar in sugarcane. The sugar extraction rate of a normal sugar refinery is between 92~97%.
Some sugar factories use steel turbine to drive shredders, sugarcane feeders and millings, as above mentioned this technology is old and outmoded. There are many disadvantages. With the development of VFD and asynchronous motor technology, more and more sugar factories start using VFDs driving these loads.
Fig.1 Shredders sugarcane feeders and millings in the sugar factory
When using mv drives for shredder/sugarcane feeder and millings, the speed of motor will decrease when the sugarcane layer is not thick enough. The press process will wait until the thickness is qualified, sugarcane layer will be fully pressed and increase above 0.2% of the average extraction rate. Meanwhile, the power saving target is achieved because of the decreasing current created by the decreasing speed.
The advantage of INVT VFDs driving:
1. The growth of sugar juice extraction rate
VFDs can help ensure the thickness of the sugarcane layer. This can increase the sugar juice extraction rate. According to the measurement and calculation, the average extraction rate can be promoted at least 0.2%.
2. Significant energy savings
Due to actual sugarcane produce requirement, these loads don't need running at full speed and full power, so there is significant energy saving. From running data on the site, VFD Drive is running at 35Hz, the energy saving ratio is about 15% by preliminary calculation.
3. The constant current automatic control
Ensuring the thickness of the sugarcane layer is very important. And it would be better if makes the motor of the current fluctuating range smaller. If motor current changes with a thick layer of sugarcane, VFD will increase motor speed to make the sugarcane layer crushed as soon as possible; If motor current decreases and with a thin layer of sugarcane, VFD will reduce motor speed to squeeze sugarcane layer thoroughly. So setting motor current always in small range will help to ensure a uniform thickness of sugarcane, which helps to improve spare rate.
4. Low torque pulse
Very low torque pulse will not cause the resonance between the motor and other mechanical devices and helps to reduce the transmission mechanism wearing.
5. Soft start
Be able to start softly, start time and method can be adjusted according to the situation on site.
Fig.2 Shredders feeders and millings with INVT VFDs