Multifunction PID controllers for sterilization of canned food

Sterilization of canned food: Determining F0 value and maintaining heat cycle to achieve desired results for different type of food.  The process needs to meet food compliance standard and the control system needs to be able to calculate F0 value and record the data in tamperproof encrypted format for audit purpose.

Gefran Solution: 3850T controller, GTF Power controller, TK Pressure sensor, 650L safety controller and GF Express common configuration tool provides complete solution for this critical application

Sterilization is a controlled heating process used to completely eliminate all living micro-organisms including thermoresistant in milk and other food but not necessarily killing harmless microbes.

The sterilization process in the canned product can be subdivided into three phases.

• Phase 1 – heating: the product temperature should go from ambient to the sterilization temperature.
• Phase 2 – holding: the product is maintained at sterilization temperature to achieve destruction of microorganisms.
• Phase 3 – cooling: the product temperature is decreased to the ambient temperature.

To reach temperatures above 100°C (212 °F) (“sterilization”), the thermal treatment has to be performed under pressure in autoclaves or retorts.  For small production as canned marmalades or sauces, vertical autoclaves are typically used with the lid on top.

Some material is heat sensitive and cannot be sterilized at 121°C (250°F). F0 value is used to determine the exposure time of material for sterilization at a particular temperature. F0 value is in the time in minute for specified temperature that gives the same thermal lethality as at 121°C (250°F) in one minute.

Considering the canned products could have diverse sterilization profiles, the Control system should provide:

• PID control with variable Set point generators
• Product Sterilizations Recipes
• Product Batch record
• Process Interlocks and sequencing functions
• Math functions and F0 value calculation

The food processing is subject to the food authority control, the batch record data should be stored in encrypted form.

In this application, the heating is done by electrical heaters.

Multifunction PID controller 3850T

• Up to 16 PID control lops- self and auto tuning
• Up to 32 dig I/O or interlocks and logic
• Configurable custom graphic display for Pre-formatted instrumentation, recording, alarm pages
• Extensive built in library of function blocks
• F0 value calculation
• Batch recording, encrypted file for data protection, export data in CSV, PDF formats
• GETlogic: Math and logic control
• Communication: Ethernet Modbus TCP/IP and VNC for remote access

Power controller 1PH series GTF

• Up to 120A 400VAC
• Configurable control mode
• Communication: Modbus RTU

Pressure sensor TK

• Rugged, strong electronics, IP 65/67 protection
• Supports long distance signal transmission

650L alarm unit

• Latched setpoint alarm relay to interrupt the output in case the safety limit exceeds the set boundary

GFeXpress – common configuration tool for all Gefran products

3850T multifunctional controller, GTF Power controller, TK pressure sensor and 650L trip alarm unit for safety meets the complete control requirement of this application (Figure 2).

Autoclave Temperature Heating- Holding- Cooling and Pressure PID control

• Complete and Precise PID control with alarms Temperature :  0-150 °C (32-302 °C), Pressure: 0 – 4 BAR
• 2 independent set point profiles programmer.
• Automatic calculation of F0 value to determine the sterilization timing required according to the temperature value
• 32 Dig I/O and GETlogic to execute plant interlocks (load–unload, doors open-close etc), alarm management and various safety interlocks

Batch recording and reports – Real time clock (RTC):

• The data are displayed in graphic trend mode along with time, alarms and events (Figure 3).
• All the process data are archived safely in internal memory of 3850T – can be saved either in standard (CSV) or encrypted files and exported via USB or Ethernet

TK pressure sensor gives analogue output which is required for precise PID pressure control through 3850T.

GTF power controller drives electrical heaters in conjunction with 3850T for uniform heating.

The Ethernet base VNC connection (Figure 4) enables remote access to the 3850T for maintenance purpose, remote monitoring and recording of the data.