Abstract : This paper discusses the method of achieving the diversity of the size of polyester slice granules by increasing the conveger and central control. It also discusses the full use of the convection converter in the production process. Key words : polyester; slice; size; convection converter 1 System Overview Longdi Group Co., Ltd.'s intermittent polyester plant can produce nearly 20 different varieties of polyester slices, including bright, semi-dull, cationic, and bottle-grade slices. In today's fiercely competitive market , the only advantage for the company to survive is product differentiation. The purpose of this equipment upgrade is to achieve a differentiated advantage in product appearance and size while minimizing costs. Therefore, maximizing the utilization rate of existing equipment is a crucial factor. It's worth noting that, to reduce costs and fully utilize the potential of existing equipment, the pelletizer cutter is driven by the frequency converter of the upstream polycondensation agitator. This is because the special process requirements of intermittent polyester mean that pelletizing can only be performed during the intermediate stage (stage III), meaning the polycondensation agitator in the entire pelleting process is idle, thus providing an opportunity for full utilization. Overall, this upgrade requires the addition of three 3.7kW frequency converters and three AC asynchronous motors of the same power (for three pelletizers) to drive the feed rollers; the cutter is driven by the existing motors, with the speed controlled by the frequency converter of the polycondensation agitator, which is switched on as needed. During implementation, the upgrade of each pelletizer is carried out independently, but ultimately all will communicate with the DCS to further achieve coordination between the pelletizers. The DCS we use is the OPTO 22 distributed control system, which has significantly more openness compared to traditional DCS systems (such as the Honeywell TDC 3000). Through free FI communication, the SIEMENS s7 (the pelletizer's built-in control system) communication port can be connected to the LCM4 controller COM3 in the OPTO 22 SNAP I/O control system using a 485 connection, thus achieving comprehensive monitoring of the pelletizer's original control conditions. The difference in pellet size is achieved by adjusting the Hz of the two frequency converters, i.e., the speed ratio between the cutter and the feed roller! [b][align=center]For details, please click: Realizing the Differentiation of Polyester Chip Size[/align][/b]