Temperature control of liquid egg pasteurization system using PLC (programmable logic controller) siemens simatic S7-200 and HMI (human machine interface) simatic HMI panel

摘要

Raw chicken egg in good condition of shell can be kept in room temperature for about a week or in refrigerator for 3 weeks. The quality of raw egg will be decrease as the longer storage time due to the increasing amount of pathogenic bacteria present in it. Salmonella is a kind of pathogenic bacteria that is found in egg. Normally, the well-cooked egg which is cooked over a temperature of 72°C can be confirmed that Salmonella has died because of high temperature. However, many processed eggs are actually consumed in a raw state, such as mayonnaise and traditional Indonesian drink (STMJ and jamu). So, raw chicken eggs need to get pasteurized to prevent Salmonella contamination in it. Pasteurization is the disinfection process of bacteria at low temperature and in a certain time frame. Based on the standards issued by the NSW Food Authority, liquid whole egg has to be pasteurized at least 64°C for 2.5 min. This research was focused on temperature control of liquid egg pasteurization system using PLC Siemens S7-200 CPU 226, HMI Simatic Panel TP177 Micro, and a Proportional controller, in order to obtain a precise temperature control design for liquid egg pasteurization system. Liquid egg pasteurization on this research was carried out at a temperature of 64°C for 2.5 min. The process of designing controller used the hand tuning method was obtained parameter value Kp corresponding to the system: Kp=3.4. Using Kp=3.4 egg pasteurization systems could reach set point of 64°C and settling time of 910 seconds. Ladder diagram of the PLC could work well as it could keep the temperature of 64°C according to standard pasteurized eggs. HMI in this study was able to show the trend of temperature and PWM view in real time.