Preliminary Research on Flaking Mills

In the Project, the frequency converter and synchronous machine of the billet mill of XX Company are subject to energy conservation transformation. There are 26 billet mills on site. The soybean billet is pressed by the billet mill as the main link of the soybean pre-extrusion process. The stability of pressing is the key assessment index. The stability of the operation of the billet mill is of great importance, especially in the peak period of production, the unexpected shutdown will cause large economic losses. At present, the billet mill adopts three-phase asynchronous motor, which operates without frequency conversion. The number of belts is 14, the diameter of the driving pulley is 240mm, the diameter of the driven pulley is 860mm, that is, the theoretical transmission ratio of the belt drive is 3.6, and the belt will be worn and loose after long-time operation. A single billet mill 1 The belt shall be replaced 4 times a year and 1 time a quarter on average.

Retrofit Plan

Based on preliminary research and analysis, the comprehensive solution for this project includes:1)VFD Upgrade for the Flaking/Rolling Mill‌;2)‌Drive System Upgrade for the Flaking/Rolling Mill‌;3)‌Retrofitting with Permanent Magnet Synchronous Motors (PMSM) for the Flaking/Rolling Mill‌.

Content of transformation

Electric Drive Solution

The flaking mill currently employs a ‌75kW three-phase induction motor‌ with suboptimal efficiency. For motors rated ‌75kW and above‌, permanent magnet synchronous motors (PMSM) demonstrate ‌2%-4% higher rated efficiency‌ compared to induction motors.

Under varying roller torque conditions (60%-120% load range):

Induction motors exhibit ‌3%-5% efficiency fluctuation,

PMSM maintains ‌1%-2% efficiency fluctuation‌8,

The project will utilize an ‌ES500A series inverter‌ for PMSM control, enabling:

Start-stop speed regulation,

Future research on optimal roller speeds for different feed grades to synchronize feed rate and roller speed via frequency conversion910.

‌Potential energy savings: 5%-10%‌.

To meet power and overload requirements, the retrofit includes:Replacing the ‌75kW induction motor‌ with a ‌110kW PMSM‌,Meanwhile, it is matched with the same frequency converter of ES500A series 132KW.

Drive mode

The existing Flaking Mill adopts belt transmission, with low transmission efficiency, and the belt will be worn and loosened after long-time operation, so the belt needs to be replaced frequently. The transmission efficiency of planetary reducer is 5% - 10% higher than that of belt transmission, with stable transmission, long service life and easy maintenance. To sum up, the transmission system of the Project is modified as follows. Under the premise of meeting the rotating speed demand of the terminal roll of FR124 billet mill, the original belt drive is replaced with planetary reducer and coupling drive, so as to improve the system stability and reduce the maintenance difficulty.

Field reconstruction picture

Before reconstruction	After reconstruction