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Title:
PLANT FOR A DEHUMIDIFICATION PROCESS OF GRANULES, PARTICULARLY OF PLASTIC MATERIAL, TO BE SUBSEQUENTLY USED IN THE MOLDING PROCESSES
Document Type and Number:
WIPO Patent Application WO/1998/055284
Kind Code:
A1
Abstract:
Plant for a dehumidification process of granules, particularly of plastic material, to be subsequently used in the molding processes, comprising two means for the dehumidification of the air to be inlet inside of a process hopper provided in the plastic material molding plants, said means when saturated, being, also alternatively, able to carry out a regeneration phase for then being ready again for a dehumidification cycle of the air to be inlet inside of the process hopper, and in which for feeding the air recirculation a double channel turbine with channels one independent from the other comprising air cycles distribution means, of which at least one for each regenerator-dehumidifier means is provided.

Application Number:
PCT/IT1998/000145
Publication Date:
December 10, 1998
Filing Date:
June 01, 1998
Export Citation:
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Assignee:
M S M SNC DI MASIERO G SEMENZA (IT)
International Classes:
B29B13/06; F26B21/08; (IPC1-7): B29B13/06; F26B21/08
Foreign References:
US2783547A1957-03-05
US5485686A1996-01-23
EP0626244A11994-11-30
US3143283A1964-08-04
US4523630A1985-06-18
Other References:
CHRISTIAN H├ľNINGER: "TROCKENLUFTTROCKNER DER MODERNEN GENERATION", KUNSTSTOFFBERATER, vol. 39, no. 5, 1 May 1994 (1994-05-01), ISERNHAGEN, DE, pages 22 - 24, XP000460707
"SECHAGE", REVUE GENERALE DES CAOUTCHOUCS ET PLASTIQUES, vol. 67, no. 699, 1 October 1990 (1990-10-01), PARIS, FR, pages 100 - 111, XP000287441
Attorney, Agent or Firm:
D'agostini, Giovanni (Via G. Giusti 17, Udine, IT)
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Description:
DESCRIPTION PLANT FOR A DEHUMIDIFICATION PROCESS OF GRANULES.

PARTICULARLY OF PLASTIC MATERIAL. TO BE SUBSEOUENTLY USED IN THE MOLDING PROCESSES Technical Field The present invention has for object a plant for a dehumidification process of granules, particularly of plastic material, to be subsequently used in the molding processes.

The invention, finds particular even if not exclusive application in the sector of the plastic materials working.

Background Art The plastic material molding lines are known. They, upstream of the molding plant, must provide some quality control systems of the raw material for guaranteeing the production cycle and quality. Said control systems, have the purpose of detecting the presence of residual humidity, present in the used material, allowing a specifical plant, in the specific case a dehumidifier, to intervene constantly or in time on the raw material, in order to feed the molding plant only with dried product, therefore optimised, maintaining a high working quality.

As a consequence also the dehumidifiers are known to many. Among these, there is a typology which intervenes directly in the process hopper, where time by time the plastic material granules are loaded.

Substantially, a ventilation system inside of the hopper is provided, allowing on one side the inlet of an air flow, preferably constant and dry, on the other one the outlet of air enriched with variable humidity percentages. Such forced circulation has the purpose of progressively reducing the humidity percentage detectable inside of

the hopper, without interrupting the working cycle, allowing in the meantime, the regeneration of the means suitable to the dehumidification of the air inlet inside of the hopper.

For proceeding to the ventilation of the process hopper, presently two lines are provided, this, as we have seen, in order to guarantee the treatment continuity, without interrupting the productive cycle.

Said two lines, in a traditional solution are essentially identical, and are made up of, besides the relative connections and electro-valves, a regenerating-dehumidification tower each comprising some molecular sieves, and a relative turbine. The turbine essential function is that of inletting the air taken from the hopper rich of humidity, inside of the respective tower, for then being dehumidified and newly inlet inside of the hopper in a continuous cycle. When a high humidity rate, detected inside of the working tower, of the two molecular sieves provisions, is reached, the plant suspends the relative circulation, activating at the same time the parallel line, in which the regeneration cycle had previously been carried out. Such cycles alternation, now in one and then in the other tower, is necessary for allowing, in the tower concerned by the air flow circulation suspension, the evaporation of the water kept inside of the molecular sieve, being of the type provided with a suitable heat exchanger.

The dehumidification plant described, inevitably presents some problems, at first the manufacturing costs, which are particularly high, thus having negative consequences on the reference market, with sales reduction. The high costs are mostly caused by the need for double components, mainly the need for the double turbine. Such duplicity makes the plant, comprised the logic unit which manages

its operation, particularly complex, making the ensemble particularly bulky, and at the same time rather anti-economical, because it is necessary to feed through the mains both the turbines, each of which has a high consumption/for hour.

For overcoming some of the drawbacks related to the application of the first solution, a second version, of the simplified type, was recently proposed. In the same, the use of two dehumidifying and regenerating towers is always provided, but unlike the previous one, the plant is endowed with a single turbine. More in detail, the purpose of the single turbine is that of allowing the circulation of the air flow to be inlet into the process hopper, suitably divided between the working tower, which dehumidifies, and the regeneration tower. In this hypothesis, thus, only the 70% of the total amount is sent through the dehumidifying tower, while the residual percentage equal to about 30% is filtered through the regenerating tower in the usual way, for then being inlet again into the environment. Finally, detecting the saturation of the previously working tower, the phase is reversed, and so for the whole duration of the dehumidification cycle.

Also in this solution, though, some problems arise. Mainly, the inability to maintain a constant ventilation treatment of the granules in the hopper, because the throttling which occurs in the tower, depending on the amount of material present in the hopper, tends to reduce the 70% percentage of air to be inlet, for deviating the difference in the regenerating tower. A second aspect, concerns the need to have at disposal a great power, which involves some high consumption. Finally, it should be enhanced the fact that anyway a certain plant complexity remains, and this determines some excessive

dimensions.

A purpose of this invention is also that of obviating the above mentioned drawbacks.

This and other purposes are reached with the present invention according to the characteristics as in the enclosed drawings, solving the mentioned problems by means of a plant for a dehumidification process of granules, particularly of plastic material, to be subsequently used in the molding processes, comprising two means for the dehumidification of the air to be inlet inside of a process hopper provided in the plastic materials molding plants, said means when saturated, being, alternatively, able to carry out a regeneration phase for then being set again for a dehumidification cycle of the air to be inlet inside of a process hopper, and in which for feeding the air recirculation a double channel turbine with channels one independent from the other comprising air cycles distribution means, of which at least one for each regenerator-dehumidifier means is provided.

In such way, through the considerable creative contribution whose effect represents an immediate technical progress, many advantages are obtained. First of all, it is an extremely functional and versatile plant, because it offers high performances, both when it is set for operating with only one tower, and when it operates with both. Some advantages, also by the time viewpoint, are noticeable, because the plant is able to reduce the regeneration times to an extent equal to about three quarters respect to the times usually needed in the previous solutions. Further, it is possible to notice a structural simplification which eases its application to the plastic materials working lines, with a considerable reduction of the dimensions. Also

by the economical viewpoint there are some benefits, because said plant, although increasing its performances, allows a fair reduction of the consumption.

These and other advantages will appear from the following detailed description of a preferred embodiment solution with the aid of the enclosed schematic drawings, whose execution details are not to be considered as limitative, but only as examples.

Figure 1., shows a scheme of the plant.

Figure 2., shows a scheme of the plant as in Figure 1, in working conditions, providing a tower in process, and a second one in the regeneration phase.

Figure 3., shows a scheme of the plant always of Figure 1., in working conditions, providing a cycle alternative to the one shown in Figure 2.

Finally, Figure 4., shows a scheme of the plant as in Figure 1., in working conditions, providing both the towers in process.

Referring also to the figures, it may be noticed that a plant (A) particularly for the dehumidification of plastic material granules, inserted into a hopper (1), is provided upstream of a complex plant for the plastic material working, particularly for the molding.

More in detail, said dehumidifier plant (A) comprises two working parallel lines, which may operate one independently from the other, or alternatively simultaneously. This is possible by providing essentially two towers (2,3) each of which, internally, comprises at least a molecular sieve and at least an heat exchanger. The main purpose of said two towers (2,3) is that of filtering the air, in a cycle of forced inlet, before this latter is let into the process hopper (1) and with the only purpose of ventilating the product in it contained.

Afterwards, the amount of air enriched with humidity, may be discharged by the process hopper (1) for being filtered again and so on. For allowing such circulation, upstream of said process, a blowing turbine is provided (4), of the type having an independent lateral double channel. The purpose of said turbine (4), is that of constantly inletting some air through one or both towers (2,3), so that the air flow, deprived of a good part of humidity, may, through some relative downstream ducts (2', 3'), be inlet into the process hopper.

Finally, upstream of the plant, and in particular of the blowing turbine (4) some systems (5,5') for the air distribution cycles are provided, at least one being corresponding for each tower (2,3), which, through a duct (6) receive the air enriched with the humidity discharged by the process hopper (1).

Furthermore, in a possible variation, it is possible to provide a sound exiting from at least one regenerating tower, which has the purpose of detecting the humidity present in the air taken from the plastic materials loading hopper, said sound, being aimed at being connected with the apparatus control logic unit allowing to carry out particular treatment cycles.