Photo credit: Frigel

Case History

Frigel: Retrofit of PET Preform Plant at Interpet Vietnam

| Preform moulding | Frigel | Scandicci (FI) | Italy

Ngoc Nghia Industry has commissioned Frigel Group to completely retrofit the cooling system of its “Interpet” PET preform plant located in Vietnam.


Ngoc Nghia Industry (NN), is a Vietnamese leader in the rigid packaging sector and PET converter, specializing in bottle blow-molding, injection molding, and cap compression molding.
Ngoc Nghia Industry has commissioned Frigel Group, as part of a series of projects, to completely retrofit the cooling system of its “Interpet” plant located in Tay Ninh province (HCMC), where PET preforms are produced.
The old system was composed of 4 evaporative cooling towers and 8 water-cooled chillers.

Main objectives

  1. Replacing of water-cooled chillers: replacement of the 8 existing water-cooled chillers, which supply chilled water to the molds, hot runners and mold dehumidifiers.
  2. Cooling towers replacement: replacement of 4 cooling towers (350 CTR each) that supply water to the water-cooled chillers, resin dryers and oil coolers of the 8 IMMs.
  3. Energy audit of the cooling system: Frigel, as part of the agreement with the customer, will carry out an energy audit of the entire cooling system, before and after the retrofit, in order to assess the actual energy saving. The data collected with the help of the Frigel MiND supervision system will be available to the customer and allow the efficiency of the new system to be assessed.

Project & Solution

The layout of the site presented the ideal conditions for a typical Frigel “Ecodry system”, consisting of high-efficiency RVM Microgel side-machine individual chillers for high performance mold cooling and Ecodry adiabatic cooler for overall heat dissipation.

1.    Replacing of water-cooled chillers

Due to the high performances required, both in terms of flow rate and temperature control, of PET preforms applications, Microgels from the RVM range were chosen for this project.
In fact, RVMs are specifically designed to reduce cooling times in the packaging applications, in particular for the production of PET preforms, caps and blown products.

They can be digitally synchronized with the molding machine and allow to search and store the best flow and temperature configurations that optimize product quality, with the minimum possible cooling time. All RVMs are equipped with high-efficiency pumps and compressor, both under inverter control, which allow an optimization of pressure-flow-temperature of each individual process. All in all, these features can allow for a cycle time reduction up to 30%.

2.    Cooling towers replacement

An Ecodry adiabatic cooling system, consisting of a total of 60 EC fans, replaced the cooling towers. Ecodry units, due to their very low noise level, negligible water consumption and the absence of bio-hazards (eg. Legionella) have been suitably installed at ground level. This allowed the installation to be carry out without interfering with the operation of the existing system.The last connections to the process were made right at the end, allowing the shortest possible downtime of the whole system and the minimal production losses.
Frigel has estimated that thanks to Ecodry it’ll be possible to achieve water savings of up to 40 mil liters per year (40,000 m3/year).

Due to its intrinsic backup capacity, the Ecodry does not require stand-by units as in the case of the cooling towers. In addition, the pumping station, as standard, is equipped with a “spare” pump which is automatically activated in the event of a failure of one of the others. The “spare” pump is automatically cycled to balance the running time of all pumps.

3.    Energy audit of the cooling system

MiND is an innovative digital solution developed by Frigel to meet the ever growing needs of modern companies to reach “Industry 4.0” and “IIOT” (Industrial Internet Of Things) standards.
It allows to observe and manage the working parameters of the machines through a multifunctional user interface, both locally and remotely, with an easy-to-use web interface. MiND is able to provide customers with a perfect supervision and maintenance tool for all Frigel equipment, both central and side-machine.

In this case, the MiND was connected via LAN cable to all the equipment and used to collect data on the energy consumption of the entire cooling system. Furthermore, simple proximity sensors installed on the molds provided the number of cycles per hour and therefore the data on resin consumption.

The data thus collected were processed and condensed into a single “KPI” parameter (Wh/kg, energy used per kg of resin). This was compared to the same values measured before the retrofit of the cooling system: the results showed an average reduction in energy consumption of -37% with a max of -47% and a min of -22%.