Isocool’s Cooling System Saves Energy For Plastics Moulding Specialist

An injection-moulded plastic container specialist has achieved substantial gains in productivity and energy savings at its production site with a modular system comprising a centralised adiabatic cooler supplying multiple mould-cooling water chillers, with integrated free cooling, installed by Isocool, part of Atlas Copco Compressors.

 

The plastic container specialist is a leading manufacturer of plastic housewares, including household storage, bakeware, DIY toolboxes, organisers, garden pots, pet care, and food. The company prides itself that all of its product output is 100% recyclable.

To increase production capacity, improve energy efficiency and enhance productivity levels, they planned to augment their moulding operations, housed in two buildings at the time, with phased relocation into an adjacent redundant warehouse. It was a move designed to consolidate all existing moulding processes, increase capacity and flexibility, while also gaining greater energy efficiency from optimised process operations that improved cycling time.

Closed circuit system

Process cold water contained in a closed-circuit cooling system is regarded as the best performing alternative to the conventional cooling tower. Rather than depending on their current centralised process water installation, with several large, energy-hungry chillers cooling 50 plastic injection moulding units, the firm sought to install a closed-circuit system that would eventually allow for an increased output from a maximum of 70 moulding machines.

The proposed scheme was based on the concept of a central adiabatic cooler with capacity to supply process cooling water to a number of single chillers each sited by its individual moulding machine. This would allow full operational control of flow, temperature, and pressure of the process water, and would be capable of isolation when not in use or when mould change procedures are carried out.

Process cooling systems specialists, Isocool, conducted a feasibility trial with an Icetemp 1T40 water-cooled chiller sited next to an individual injection moulding unit. As a result of the positive results from the trial, Isocool designed and installed a complete closed-circuit cooling system for the initial installation of 11 moulding units based within the new production site.

The modular installation comprises an externally sited central adiabatic cooler, point-of-use chiller units, control panel, inverter-controlled process pumps, and a blow back system. In addition, an 8,000-litre insulated buffer tank, together with new water mains coupled to a strategically positioned valve, has been designed to be ready to connect process cooling water to additional moulding units’ chillers in the event of future production expansion.

Adiabatic cooler system

The central adiabatic ADcooler ADC 850/L supplies cooled water pumped to the condensers of the Icetemp point-of-use chillers and as a cooling source to the hydraulic power packs driving each of the plastic moulding machines. It is an air blast cooler whereby the process water is cooled by the ambient air flowing through two exchanger coils via axial fans to form a free-air cooling system. The principal benefits of this type of unit are that there is no process water consumption, no spray water in the air stream, or problems with water stagnation. High performance can be maintained even with air temperatures above 40°C.

Point of use chillers

The system’s chiller units are designed for the precise control of both the cooling and the heating temperature (+/-0,1°C) of the injection moulds. Sited at point of use, they are able to provide high water flow rates with increased pressure to help reduce temperature changes on the mould, and to optimise performance when producing packaging items or other types of thin-walled plastic end products. There is a heat exchanger inside each chiller that pre-cools the cold water coming back from the mould, so it continues to provide both mould and hydraulic oil cooling when free cooling is available.

Free cooling

Operation of their cooler/chillers system is based on ambient conditions, so in summer it just works to provide condenser or hydraulic oil cooling. In other seasons when ambient temperatures are low enough, the control system enables return water coming back to the Icetemp to force the adiabatic unit to work harder and supply equipment cooling water directly, bypassing the refrigeration system on the chiller. This free-cooling facility reduces plant running costs considerably thanks to a corresponding reduction in energy consumption, which results in turn in an environmental benefit.

Blowback system

In addition to the closed-circuit cooling scheme, Isocool designed and installed a custom-built mains cold water filling and mould evacuation system that works independently from the main cooling network. With its own stainless-steel pipework, storage tank, and automatic filling facility, it fulfils an essential role in bypassing the main coolant supply when it is necessary to stop a machine or carry out a mould change. It is important to evacuate all the cooling water from inside the mould to prevent corrosion.

This type of closed-circuit cooling is more energy efficient because the customer is not running a big chiller unit. The adiabatic cooler system incorporates free cooling, so if a particular moulding machine is not running, nor is the chiller, so the moulding process is optimised. That results in productivity gains and substantial energy savings as well.

Isocool’s team were commended for their co-operation, timing and organisational capability during the installation period.

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