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EcoChill Uses RDM Control and Monitoring System to Deliver Major Benefits in Kerifresh Chiller Upgrade.

 

THE PROJECT

Kerifresh is New Zealand’s largest grower of citrus fruits. Based in Kerikeri, it produces over half of the NZ citrus crop, along with blueberries and Kiwifruit, and exports it to Japan, SE Asia and Australia.

The company prides itself in the quality of its products and its approach to environmental protection, investing in the latest technology for growing, harvesting and optimizing fruit quality and shelf life.

It’s post-harvest and distribution facility holds mainly Kiwifruit and citrus fruit, at any one time storing 100-plus tons of Kiwifruit alone in specially controlled rooms. Due to the growth of the facility over time, the control and lay-out of environmental control plant was not ideal. The system was inefficient and had difficulty maintaining optimum conditions across the fruit storage rooms.

The purpose of the project, designed and installed by EcoChill, was to implement a new state-of-the-art control and monitoring system, to deliver the lowest possible energy use while maintaining optimum conditions for fruit quality and shelf life.

 

THE CHALLENGE

The system was under the control of an outdated control system that had been in use for many years. Chillers 3 and 7 were equipped with two cooling systems for each room, sharing the load. Units 3A and 7A are in a plant room situated next to the cool store, while units 3B and 7B are located in a separate plant room 50m away.

This resulted in a number of problems:

  1. Temperatures in the store rooms were poorly controlled, leading to large variations in core product temperature;
  2. The existing control system delivered poor control of cooling the plant, with multiple generic units linked with plc relay output board controlling solenoids, compressors and condenser fans;
  3. Electric defrost was fixed duration, controlled by a mechanical time clock with no other form of termination;
  4. System pump down was controlled by mechanical pressure switch.

It was clear that the problem was not the cooling plant itself, but the inadequate control system, which was failing to optimise performance energy efficiency.

 

THE SOLUTION

Following discussions with the client, a decision was taken to install a bespoke system with specific control logic, designed and written by EcoChill for the Kerifresh cool store application.

Matthew Darby, managing director of EcoChill, advised: “We chose RDM due to the flexible nature of the product – it enables us to tailor the software to suit the specific control requirements. It is also easily expandable, and enables us to easily add to the system in future without major disruption.”

With two plant rooms in different locations, the RDM PR0650 Intuitive TDB controller was installed in the main plant room, with a PR0661 Intuitive Expansion I/O board installed into the second plant room. The two controllers communicate with each other via a CANBUS network.

A full-colour touch-screen was installed in the main plant room to allow the client to change temperature set-points, initiate emergency defrosts and view alarms with a simple touch of the screen.

Specific improvements to plant operation and control included:

 

THE BENEFITS

The new system has achieved its objectives and is delivering significant benefits in terms of plant performance, reduced energy use and improved product quality and consistency.

By installing the RDM control system, EcoChill has achieved the following specific improvements:

Matthew Darby said: “Overall, the customer was very impressed with the user friendly nature of the system – in particular the simplicity of the touch-screen in managing operational changes with ease, and without the need for in-depth technical knowledge.”

He added: “From the designer and installer’s point of view, the system gives us the freedom to write our own programs to suit the specific requirements of each application. It enables us to say, “We can do that” to our customers, which is of course very powerful and attractive.”

Following the success of the project, he reports that the client is keen to roll out similar upgrades with EcoChill in other parts of the facility.

 

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