Refrigeration systems for water bottling plant
The customer is today one of the world’s largest manufacturers of bottling plants, PET bottle blowing machines and packaging machines. The group is made up of several companies, which manage the production of the various components, thus offering turnkey plants manufactured according to the customer’s requirements.
In a country like Dubai, where there are no waterways and wells are very rare, the production of drinking water has a strategic function. This is the purpose of the Mai Dubai plant, which encompasses all stages of production: from desalination and purification of seawater, to bottling it and preparing it for distribution.
Three lines produce bottles of different sizes for a production capacity of up to 12,000 bottles per hour, using a PET blowing machine. The bottles are then filled, labelled and packed on pallets.
For the correct operation of the bottling lines it is necessary:
– cooling of water from desalination and drinking water treatment from 45°C to 30°C, with a flow rate of 75 m³/h
– cooling of PET bottle moulding dies, oven circuit and electrical control panels.
Due to the complexity of the plant, the customer chose Cosmotec not only to supply the chillers but also to design and integrate the entire cooling system into the bottling lines.
Great attention has been paid to the system’s operating logic, especially in the integration of the energy sources present and in temperature management, to ensure efficient operation even in particularly invasive environmental conditions.
The products supplied by Cosmotec are:
- 3 Chiller WPA multiscroll : Cooling capacity of approximately 500 kW each, with water outlet at 18°C and ambient T of 40°C. Equipped with a double refrigeration circuit, each with tandem compressors, to vary the cooling capacity at partial loads and ensure redundancy in case of failure. The high external temperatures, which can reach up to 50°C, would have required the use of a high temperature chiller with R134a refrigerant; Cosmotec has however devised a solution that can operate the WPA units, equipped with R410A refrigerant, at full load in these conditions, thanks to the addition of a condensing module to the 4 already provided for this refrigeration capacity. The combination of R410A and reduced condensing temperature leads to a net increase in energy efficiency. The chillers work in parallel and in sequencing, managed by the C2020 electronic control, whose control logic favours the simultaneous and partial load operation of the 3 units; this mode is much more efficient than full load operation, also thanks to the reduction of the ON-OFF cycles of the compressors.
- Heat exchange group: 316L stainless steel heat exchanger for food applications where the process water, produced by WPA chillers, cools the drinking water before bottling. An electropneumatic proportional three-way valve, controlled by a temperature controller, controls the temperature.
- Chiller WLWD8: The 50 kW water-cooled chiller is used to cool the PET container moulds, the oven and the electrical control panels of the lines. The WLWD8 chiller was preferred to an air-cooled chiller because the process water in the storage tank has a temperature of 20°C, which is more constant and lower than the average outside air temperature. Condensation therefore takes place at lower temperatures, increasing the overall efficiency of the system.
- MIDR2500 Hydronic unit: Part of the circuit of the WPA units consists of a 2500l tank, insulated and complete with expansion vessels and safety valves. The positioning of the storage tank on the warm side of the circuit allows the efficiency to be optimised, as it reduces the thermal dispersion, an important factor when considering the high external temperatures. This choice allows a lower thermal inertia at system start-up. Three pairs of pumps work redundantly to recirculate the process water. A seventh pump supplies condensing water to the WLWD8.