Automatic modular systems offer up to 10,000 - 12,000 kg/h capacity for stable and gentle drying, all without requiring either compressed air or cooling water. Good quality process in drying plastic granulate materials involves management and control of the 10 factors influencing the drying process: type of material, granule size, bulk density, temperature, dew point, residence time, specific air-flow, initial air moisture content, final residual air moisture content, viscosity.
Drying effectiveness is also determined by the speed of migration of water mole-cules from centre of granules to the outer surface. The lower the dew point, the better the final result. This will be better also as it concerns the final moisture that will be obtained in less time. Ability of air to absorb and remove the mois-ture depends on how low the air dew point is and the moisture having a low dew point, the temperature at which it condenses on relatively cool surfaces.
Moreover, for the treatment of highly hygroscopic polymers, the following factors cover a main role:
1. constant performance
2. automatic variable airflow
3. high performance with constant dew point at –65° C
All of these factors have been taken into account by Italian plastics ancillary equipment producer MORETTO in the design of a new drying system for plastics, particularly for the PET treatment.
By means of zeolite, a mineral of volcanic origin, as molecular sieves, a lower energy consumption compared to the conventional dryers is reached. This kind of drying is also the basis of the new MORETTO project dedicated to the PET treat-ment. It is the FLOWMAX system which combines efficaciously the technology of the new X MAX dryers and the Flowmatik device.
In this way, it is possible to meet large drying volumes, up to 5,000 kg/h, through combination of between 3 and 10 modular design X MAX dryer units. The particular feature of the new X MAX drying systems is the constant perform-ance. In fact, X MAX is a multi-tower system at constant performance. While a dryer is in regeneration, the other units continue in operation until they too are submitted one after the other to regeneration. Not only does this ensures a steady process, but also it guarantees the rotation of the X MAX units for the re-generation which can be also in 72 hours or up to 100 between a cycle and the following one in the same drying tower.
Another interesting feature is the automatic regulation of the air according to the necessity. The control of the drying group can reduce the airflow of all the ma-chines in parallel but it will be possible to switch off the unit which is not neces-sary, modulating from 50% to 100% those ones necessary for the production. This allows to get low energy consumptions but also an added benefit in terms of control of both the thermal stress of the material which is dried and the fluctua-tion in its viscosity which is reduced to a minimum.
The plus of X MAX dryers are further improved with the coupling with the Flow-matik system that allows to configure the innovative FLOWMAX system. The effi-ciency of FLOWMAX is proved by some features which make it suitable to satisfy the most demanding requirements:
Extreme modularity: the dryer can be composed by from 3 up to 10 dry-ers with a maximum number of 32 connected hoppers.
Constant performance: thanks to the use of single units, regenerated al-ternately, the result is a constant average value that guarantees a suit-able low cost treatment with a dew point of about –65° C.
Variable airflow: Flowmatik calculates the airflow needed for each hop-per. FLOWMAX Control collects the requests, calculates the airflow and manages the X MAX units. It sets the units not required for production on stand-by and manages the remaining units in order to cover the specific airflow required by Flowmatik.
Touch screen control: the management of the system by mean of a col-oured touch screen panel is simple, functional and intuitive.
The FLOWMAX system can have different configurations according to the individ-ual requirements: the combinations Flowmatik Uni, Twin and Multi with the 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 con-sumption. Besides, they don’t require compressed air and cooling water.
FLOWMAX UNI is composed by a battery of X MAX units with a single hopper suitable for the throughput to be done. It is used for the dehumidification of big quantities of plastics, up to 10,000-12,000 kg/h.
In the treatment of numerous materials, X MAX combines perfectly with Flow-matik, realizing the Flowmatik Multi configuration and realizing an efficient and functional system able to satisfy big production needs.
For the realization of centralized systems, the configuration FLOWMAX PET Sys-tem permits to have a complete system guaranteeing process constancy, simple management and a drastic reduction of the PET treatment cost.
In case of particularly narrow spaces, instead of the battery of X MAX dryers, MORETTO can develop PET systems where a dryer is installed on board each sin-gle hopper on the IMM. Apart from the space, the systems are supplied together with the MOWIS centralized supervision system.
The operation of these high airflow drying systems is very simple; the operator sets only two parameters on a user-friendly touch screen interface: the type of material and the throughput. Then the system activates automatically with the selection of the exact quantity of process air. This allows to get an optimized dry-ing and feeding to one or more IMM which produce PET preforms for the follow-ing blow moulding which transforms the preforms into bottles.
This new system is marked with the “Green Factor” label, considering the par-ticularly low energy consumption. This comes from the results of the tests made comparing the system based on FLOWMAX and a conventional system for the PET drying.
The conventional systems at present on the market have a maximum dimension of about 4,000 m³/h and generate a throughput of up to 1,300 kg/h. This corre-sponds to the production of an IMM with 144 cavities, so a drying system with a maximum capacity dedicated to a single IMM. FLOWMAX can reach up to 8,000 kg/h of PET with a modular generator of 20,000 m³/h. A modular system of big dimensions is much more advantageous compared to individual systems which have more working components and imply a higher risk of failures of the compo-nents.
Besides, FLOWMAX has particular circuits that allow to recover the total energy used in the system and to process every Watt in the polymer treatment. Thanks to this exclusive characteristic, the investment return is guaranteed in only 2 years considering only the reduction of the energy cost. Considering this excep-tional advantage and assuming that this investment is projected at least in the next 10 years, from the third year it is on profit. The containment of the energy costs in 8 years allows a savings such as to present a new IMM. MORETTO has simulated a battery of 5 machines with 72 cavities with a production of about 3,600 kg/h and has calculated the cost with reference to the drying. The tests have been realized in European condition – temperature 20° C, relative moisture of 80% and based on 6 hours of treatment at 180° C with a specific airflow of 2.5 m³/kg on 8,500 hours/year of production.
The following graph shows how the cost of the equipment is not important, while a strategic role is covered by the energy cost which represents the 90% of the total costs in 10 years of use.
When the fast amortization has been obtained through the lower energy con-sumption, the difference of 23% in the subdivision of the costs can be considered profit and can be used to obtained competitive advantage in the market ranking.