Drying systems: "pay as you save" offer from Moretto

MORETTO (Massanzago, Italy) is offering to install the EUREKA drying system without  purchasing contract and will merely charge a monthly fee based on the amount of energy savings, calculating the differential between the ‘old’ and the newly installed equipment. After two years, the system will have been paid for and owned outright by the customer. This will be achieved just through energy savings. If not satisfied, the system(s) can be returned to MORETTO at no extra cost to the customer.

The innovative EUREKA project is geared to provide moulders – treating primarily PET – with an alternative and totally new business model to tackle the second highest cost, after raw material cost, i.e. energy, some 30 percent of which is attributable to drying. Offering moulders a no-risk acquisition plan, MORETTO encourages moulders to try out, and eventually own, the new equipment. Instead of either the outright purchase, lease of equipment or alternative finance options, the customer is invited to negotiate the power consumption and other operational costs of his existing equipment with the new EUREKA system.

The basis for the new MORETTO EUREKA project – designed to reduce energy consumption consistently and improve performance and quality – is the new multiple unit X MAX system (X MAX dryers combined with the FLOWMATIK controller and the state-of-the-art OTX hoppers), with its single desiccant bed, i.e. twice the size of conventional beds. Reduced energy consumption is achieved by the use of zeolite, a volcanic mineral, as a molecular filter. The air flow channel of the X MAX dryer is situated in the centre with the heater in the middle of the channel. With the heat exchanger also at the centre, complete recovery of regenerated energy is assured, as every Watt of energy is used in the polymer treatment.

The fully automatic high-volume modular MORETTO drying systems enable a throughput of up to 8,000 kg/h capacity, in combination with a modular generator of 20,000 m³/h – giving total flexibility of between three and 10 modular design dryer units and from 1 up to 32 drying hoppers, all without requiring either compressed air or cooling water. The result is faster, consistent and gentle drying of highly hygroscopic polymers – such as PET – with the benefit of a significant reduction in energy consumption. The factor separating this multi-tower system from conventional systems is the maintenance of a consistent, i.e. uniform, dew point throughout the process, thereby reaching high efficiency levels and total operating flexibility, for example in the mix of preform sizes and weights. Efficiency is never compromised – even at lower throughputs. 

The ‘green-factor’ labeled system with its extremely low energy consumption accommodates increasing throughputs of, for instance, PET preforms. This is particularly important as numbers of mould cavities are ever increasing. All the vital factors which influence the management and control of the drying process of numerous plastic granular materials – and PET in particular – are taken into consideration: type of material, granule size, bulk density, temperature, dew point, residence time, specific airflow, initial air moisture content, final residual moisture content in the granule, and viscosity. In a multi-dryer system, each unit, with its stand-alone air circuit and controlled by a dew point meter, can be set at the same temperature and air-flow rate, whilst simultaneously staggering the different dew points. The FLOWMATIK controller manages all relevant sequences – no simultaneous regenerating is necessary – so that the mix of process air from the dryers maintains a constant value of around -65° C.

The graph shows that a lower dew point value improves the final result in terms of ppm, in the same time and with the same temperature.


The integrated FLOWMATIK controller is designed and programmed to detect each hopper’s capacity and the material’s bulk density, the desired resident time, temperature, and the air flow rate. “Once you have control over the process, the exact drying time needed can be established. All you have to enter is the material type and the desired throughput rate; the system will take care of the rest”, according to Renato Moretto. By tailoring airflow to the throughput rate, higher savings are obvious. His innovative ideas go even further: The FLOWMATIK Split system divides the PET to be dried first into a larger hopper at a relatively low temperature, then into a second, smaller hopper at the customary 180° C. The efficient approach of EUREKA is designed to reduce airflow needs by more than 50 percent. Research into greater efficiency and improved user benefits utilized computerized fluid-dynamic and thermo-dynamic simulation trials to analyze current leading hopper designs. Non-uniform flow through the hopper, combined with temperature gradients of up to 80° C (from centre to outside), have been identified. In addition, material can contain twice as much moisture as the average of the hopper in its entirety. The conclusion: given a nominal four-hour residence time in the hopper, some material exits in as little as 2.5 hours’ time.

Another processing benefit is that one dryer can be taken off-line, whilst a newly regenerated dryer (standard with the system) is installed as a replacement. In order to achieve not only a considerable reduction in energy use, more uniform heating and efficient regeneration at lower airflow rates are possible.

The FLOWMAX system can be utilized in a number of different configurations according to individual requirements: i.e. FLOWMAX UNI (a battery of X MAX units), Twin and Multi with X MAX dryers creates complete Uni and multi-hopper systems which are able to meet a wide range of needs in the feeding and drying with very low energy consumption. FLOWMAX UNI comprises a battery of X MAX units with a single hopper, enabling dehumidification of large quantities of raw materials – up to 8,000 kg/h. In fact, X MAX is a multi-tower system at constant performance. While one dryer is in regeneration, the other units continue operation until they, too, are submitted to regeneration – one after the other. Not only does this ensure a steady process, but also it guarantees the rotation of the X MAX units for regeneration which can be also in 72 hours or up to 100 between a cycle and the following one in the same drying tower.

The redesigned state-of-the-art MORETTO OTX hopper with its new geometry solves the problem of the non-uniform fall flows of the granules, allowing to manage the process efficaciously. Also the air diffusion has been optimized eliminating the temperature differences. “Unlike the uncontrolled mixing occurring in conventional hoppers, our hopper achieves a much more uniform moisture ppm in less time”, explains Renato Moretto. To give an example, increased ppm control and uniformity results in a reduction in drying time from the typical six hours to an average of four hours and even less. In addition, drying temperatures can be reduced from 180° C to 175° C, also cutting air flow by up to 40 percent, whilst achieving 20 ppm final moisture (See graph).


image To summarize, by using the new MORETTO hopper, an identical throughput can accomplish a 30 percent decrease in drying time, 40 percent reduction in air flow requirement, and a 25 percent drop in hopper volume. Each hopper has its own heater, an airflow valve to allow for automatic variables, and a flow meter, accommodating from 1000 to 10,000 litres, thus providing a flexible high volume, highly efficient system.