Systems are the hot new added ingredient for today's curries
With a typical curry sauce plant now producing up to 1500t of product a week to gourmet standards, control engineering has become a key ingredient.
A joint effort between the technology provider Mitsubishi Electric and Lancastrian process engineering company BCH Group, has come up with a system designed to meet the current and future needs of one such food manufacturing group.
The company's cook-chill plant includes two base curry tanks, four cooking vessels of varying sizes, auxiliary or pre-mix tanks for making up starch and milk powder, and an array of cooling tanks. Such a set-up can be configured into a number of different subsystems for flexibility of production, with each being controlled by a dedicated Mitsubishi Q series programmable logic controller (PLC). Among other tasks, these PLCs monitor temperature, set the mixing time and control the Mitsubishi inverters on the agitator drives to change the speed as mixing progresses.
Serial links are used to connect the PLCs to a number of Mitsubishi human machine interfaces (HMIs). Each of these is programmed to display a set of different pages. One page is an overview graphic of the whole plant; others depict parts of the plant in greater detail to allow local monitoring and control by operators.
There are also two cleaning-in-place (CIP) systems. The first is for low-risk areas, the second for high risk sections. Communication with the CIP systems is via CC-Link, the Mitsubishi-developed open fieldbus protocol.
Between them, the PLCs support 14 separate ASI networks that control nearly 500 process control valves dotted around the plant. All of the valves were supplied by APV complete with built-in ASI interfaces so that installation and commissioning could be undertaken rapidly.
All the PLCs are networked using a Mitsubishi MELSECNet to a master Q25 PLC, which manages the overall operation of the plant, co-ordinating product transfers between vessels, activating cleaning processes, recipe checking, feeding the finished product on to the plating/packaging lines etc.
The master PLC also communicates, using Ethernet, with a Mitsubishi MX2000 supervisory control and data acquisition (SCADA) system, linked into the company's enterprise resource management system.
Contact: Mitsubishi Electric, Tel: 01707 276100
