ETA-process®: High thermal efficiency through utilisation of the return air – savings of up to 40%

Motan ETA-process® technology   Cost-efficency is highly valued everywhere. In plastics processing, the drying of hygroscopic plastics is a cost factor which is not to be underestimated. At first glance, some conventional, low-priced drying systems reach an efficiency of less than 50%. Motan dryers with patented ETA-process® however, are real cash boxes: The specialist's technology for material handling reduces the drying costs by up to 40%.The drying of plastic granules before processing is the most important prerequisite for high quality products, efficient production and trouble-free manufacturing. In growing competition and with increasing cost pressure, the used raw materials, the machinery and the energy must be optimally utilised. Motan took account of this with the so-called ETA-process® – named after the designation for efficiency. Resulting from the process, the unused heat from the drying bin is directly returned to the bin via a heat exchanger. Depending on the material grade and consumption, this reduces the drying costs by up to 40%.For the drying process, four parameters (their correct settings as well as relations to each other) are essential for the drying process: drying temperature, air volume or air flow, dewpoint and drying time. Here, the intelligence of the ETA-process® comes into play: This means that the process works with the ideal parameters of each plastic material. Through the respective adaptation of air volume, drying temperature, dewpoint and drying time considerable energy savings are achieved.The technical starting point for the ETA-process® was the assumption that the drying parameters indicate ideal values and are also in an ideal relation to each other.ETA-process®bin   The principle of the process is the optimum utilisation of the waste heat from the drying bin and is characterised by two essential features. The heating for the drying air is arranged directly in front of the air inlet into the material to be dried. Thus, dry but cold air is led to the drying bin and only there brought to drying temperature. Temperature losses by radiation from the pipework are avoided and expensive insulation is no longer required. The resultant unused heat in the drying bins is utilised in a heat exchanger for pre-heating the process air (dry air) before the return air is dehumidified again in the dry air generator. The energy in the return air is made use of and at the same time the return air is cooled down to the low temperature required to achieve sufficient adsorbtion by the molecular sieve and to ensure a low dewpoint for the dry air. Expensive water after-coolers in the return air process are not required.Motan engineers carried out series of measurements with different drying temperatures, material throughputs, bin sizes and heat exchangers. The tests showed that using ETA-process® in conventional systems, the commonly accepted energy loss in the drying circuit amounting to approx. 47%, could be reduced to 22% - i.e. more than halved. Exceptional energy savings are possible, in particular with materials dried at high temperatures - such as PET.Temperature profile in dryingsystems without ETA-process®   Temperature profile in dryingsystems with ETA-process®With regard to cost efficiency, Motan ETA-process® should generally be used with drying temperatures as low as 75 °C, since already with these materials, savings of more than 10% can be realised. With drying temperatures over 100 °C the cost benefit is more than 20% compared to conventional drying systems. Besides the energy potentials in the drying bin, as part of the ETA-process® concept, energy is also reclaimed through a heat exchanger in the regeneration process. Recooling the freshly regenerated cartridge in the closed loop mode avoids preloading the desiccant with moisture from the ambient air during the cooling phase. Therefore, the drying system can be used whatever the weather and the season. In total, these measures secure energy savings of approx. 40% for the regeneration process.   Energy consumption of drying systems in watt hours per kilogram of dried material. Comparison between inherent required drying energy and additional consumption with rising temperature for material drying in conventional systems and with Motan ETA-process®.In addition, longer residence times of the material in the bin – for example due to smaller throughputs or down time – do not result in material degradation, since the drying temperature is lowered automatically to a throughput-adjusted temperature (Motan DryingOrganizer). At the same time, temperature lowering means lower heat output with lower exhaust air heat. This leads automatically to considerable energy savings. So, Motan drying systems with ETA-process® are real cash boxes.Customer's benefit is Motan's focus!Costs: Huge reduction in energy costs through heat recovery No cooling water required for after-cooling Small footprint through compact design Simple ductwork, without complex insulation Up to 40% additional cost reduction in material drying compared to conventional energy saving drying systemsQuality and safety: Optimum drying quality; constant temperature, defined air volume Self-regulating drying temperature (heat output) at changing operational states Arbitrary temperatures for all bins No wear parts, therefore high reliability Easy operation, maintenance-free

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