Focus on: Cooling Energy & Environmental Management October/November 2024 www.pwemag.co.uk Plant & Works Engineering | 31 which the replacement chiller and associated pipework all had to be completed. In addition, the chiller plant sits within a room which presents a very confined space to work in. This also means that the connecting pipework needs to change direction several times.” Pullar called in Isocool, who installed and maintained the original system and continues under the name of Atlas Copco to be Polypipe Building Services’ cooling supplier of choice, to support the upgrade. Cooling requirements Temperature control is critical to the quality of Polypipe Building Services products. Polymer production at the Aylesford site uses two-stage mixers (hot and cold). The polymer is blended at an optimum temperature of over 100°C before passing into a cold mixer for rapid cooling to 50°C. Once cooled, the polymer is then pumped to dry blend silos, pelleted and extruded into shape. Each batch takes approximately eight minutes to process. Polymer production of this scale requires cooling water at a constant temperature of 15°C and a flow rate of 80m3 / hour. This equates to 200kW per chiller. To improve efficiency and reduce energy consumption, Polypipe Building Services decided to upgrade the chiller plant to a new ‘free air’ system. This means that when the ambient air temperature falls below a set temperature, the chillers switch off and use the outside cool air to chill the water. Cooling system configuration Isocool designed, specified and installed a new cooling system to meet the specification and address the confines of the existing plant room. James Cowen, Regional Sales Engineer, Process Cooling Solutions at Atlas Copco, said: “Our primary focus is always on delivering the best value for our customers. For this project, we used a combination of Eurochiller products and third-party equipment to address the space restrictions and deliver the cooling levels that the application demanded.” The main cooling plant comprises a Eurochiller DC 400/L AD self-draining free air cooler and a Eurochiller ADC 500/L adiabatic cooler. Sited on the roof, both these chillers are designed to withstand harsh external environments. The free air chiller is programmed to switch to ambient air cooling if the temperature falls below 15°C. The adiabatic cooler uses a special pad rather than spray bars, which eliminates water droplets from the air stream. Combined with one-time water use, this dramatically reduces the risk of legionnaire’s disease and lowers maintenance requirements. Two water-cooled chillers further reduce the process water temperature prior to it being introduced into the cold mixers. In addition to the main chiller equipment, Isocool supplied ancillaries including a new water storage tank and replaced all the recirculation pumps and associated pipework. Unusually, they did not use traditional metal pipes for the task because the physical constraints of the plant room made welding steel pipework problematic. However, Polypipe Building Services supplies a plastic piping system called MecFlow, which offered a potential solution. Cowen commented: “It’s not every day you are able to showcase a customer’s product as part of a system upgrade, but we seized the opportunity. We had to allow for the insertion depth of the MecFlow weld joint, which was a slight change to working with stainless steel, but following training with Polypipe Building Services, our team was able to achieve a seamless join and the system works very well.” Despite all the time, space and technology challenges they encountered, Isocool succeeded in removing the old plant and installing and commissioning the new plant within the two-week shutdown period. This included the construction of a temporary platform around the roof to support the new cooler during installation. Pullar concluded: “Atlas Copco Isocool delivered for us on every level. We hit our maintenance window, we have a fully upgraded process water cooling system, and we have reduced our energy consumption significantly, which is a great return on investment.” For further information please visit www.isocool.uk www.atlascopco.com/en-uk/compressors
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