INVT GD5000-S MVD Applied to Pressure Feed and Mill Production of the Sugar Plant in Thailand

Abstract: Pressure feed and Mill for the sugar production is one of the most important equipment in the sugar industry. This article introduces a successful application case of GD5000 - S medium voltage drive (MVD) in Pressure feed and Mill for the sugar production plant in Chon Buri, Thailand

Keywords: Pressure feed, Mill, Sugar, GD5000-S, MVD

1. Forewords

Pressure feed and Mill are an essential component of the sugar industry. The sugarcane production process generally includes juice extraction, purification, evaporation, crystallization, honey separation and drying. Juice extraction is an important link in the whole process, and the press is an important equipment for extracting sugarcane juice by pressing method. According to the data analysis, if the extraction rate is increased by 1%, the total recovery rate of sugar is increased by 0.88%-0.92%. However, in the press process, there are many factors affecting the extraction rate of the press, roughly the following points:

1. Sugar loss in bagasse. Because sugarcane juice and bagasse are separated during the crushing process, and bagasse is rich in fiber components, when the bagasse leaves the press outlet, it will expand, and at this time, the bagasse will absorb part of the juice that has been squeezed at the outlet with its own expansion. At the same time, affected by the efficiency of the press, it is impossible to squeeze all the sugar in the sugarcane.

2. Crushing degree of sugarcane. Especially for the pre-pressing process, the crushing degree and shape of sugarcane are the premise to ensure the extraction of the whole pressing system. With good crushing degree of sugarcane, the juice of sugarcane is easy to press out, and the seepage effect is improved.

3. Water content of bagasse. The reduction of bagasse moisture is the guarantee of improved extraction.

4. The uniformity of tearing machine. The uniform thickness of the cane layer transported by the ripping machine is very important to improve the extraction rate. If the cane layer is too thick, the press is not thorough, resulting in waste of bagasse; If the sugarcane layer is too thin, the sugarcane layer is pressed, and the water content of the bagasse is too high, which affects the extraction rate.

5. Mechanical wear of the press roll. At the end of the pressing season, because of the more and more serious wear of the press roll, the gap of the press roll expands, and the extraction rate decreases.

2. Project introduction

The project is located in a sugar plant in Chon Buri, Thailand. INVT provided special Split MDV’s which have modified transformer with input voltage 3.3kV and output voltage 6.6kV.
* Device information:

* One-line diagram of system main circuit:

Fig.2 One line diagram 

* Scheme description:

The 3.3kV high voltage is input to the inverter, and the output of the inverter is 6.6kV connected to the motor.
The DCS outputs analog signals to the frequency converter according to the demand of the production sugar volume to adjust the operating frequency.
MVD system advantage:

1. Can achieve soft start, start time and start mode can be adjusted according to the site conditions. 

2. High power factor, up to 0.95 or more, no need to add a power factor compensation device, to avoid the penalty caused by reactive power.

3. The motor does not produce harmonic pollution, effectively reducing the heat of the motor.

4. The torque pulse is very low, will not lead to the resonance of mechanical equipment such as motors, but also reduce the wear of the transmission mechanism

5. The output waveform is perfect, and the distortion is less than 4%.

3. Field site photos

Fig.4 Field site photos

4.   Conclusion

For the sugar mill, the conversion of AC frequency can not only improve the process flow, but also increase the production efficiency. It can also improve the extraction rate of sucrose and increase the yield. At the same time, it has considerable energy-saving effect and reduces energy waste. The site operation effect is good, has been affirmed and recognized by customers.
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