WO2001036083A1

WO2001036083A1 - Astatic device for pressurized reactors and cyclones to be used in processes for making plastic materials, in particular for polymerizing olefines

Info

Publication number: WO2001036083A1
Application number: PCT/IT1999/000378
Authority: WO
Inventors: Davide Barbui
Original assignee: Ace Di Barbui D. & Figli S.R.L.
Priority date: 1999-11-19
Filing date: 1999-11-19
Publication date: 2001-05-25
Also published as: EP1235641A1; AU1296400A

Abstract

An astatic device (1) for pressurized reactors and cyclones for making plastic materials in general and, in particular, for polymerizing olefines, comprises an astatic bar (2) which can be applied inside a reactor or cyclone vessel body (4) and including an inner insulating body (30), to which are coupled a plurality of pointed elements (36) capacitively coupled to a conductor (21) covered by a dielectric material (35) and housed in the insulating body, the conductor (21) projecting from the vessel body and being adapted to be coupled to a high voltage power supply.

Description

ASTATIC DEVICE FOR PRESSURIZED REACTORS AND CYCLONES TO BE USED IN PROCESSES FOR MAKING PLASTIC MATERIALS, IN PARTICULAR FOR POLYMERIZING OLEFINES

BACKGROUND OF THE INVENTION

The present invention relates to an astatic device for pressurized reactors and cyclones to be used in processes for making plastic materials, in particular for polymerizing olefines.

As is known, for making polyolefines such as polypropylene and polyethylene, by polymerizing said olefines in the presence of highly active catalyzers, it is necessary to bring the inside pressure of the reactor to a value of about 30-65 bar and the temperature from -40° to 150°C.

Under the above mentioned conditions, the polyolefines will be caused to expand to assume a spherical configuration adapted for extrusion processes .

However, in said conditions, the rubbing of the polyolefine particles will generate electrostatic charges susceptible to adhere to the reactor walls, thereby generating difficulties both in metering the raw materials and in the transforming processes thereof .

Thus, it would be desirable to provide an astatic device adapted to fully remove the electrostatic charges in the powder plastic materials, as well as in recovered ground plastic materials, as they are stored in storing hoppers and silos. Moreover, the above mentioned rubbing of plastic material particles and ground powders in said storing hoppers and silos would cause the electrostatically charged particles to be attracted to one another or to the hopper and silo walls, thereby generating the so-called "bridging" effect hindering a proper metering and exiting of said materials.

The above mentioned drawbacks, moreover, as stated, also hinder the transforming production processes such as extrusion, injection molding and packaging processes.

SUMMARY OF THE INVENTION

Accordingly, the aim of the present invention is to overcome the above mentioned drawbacks, by providing an astatic system for pressurized reactors and cyclones for carrying out processing methods of plastic materials in general and, in particular, for polymerizing olefines, allowing to remove the electrostatic charges on the plastic material particles, thereby preventing said plastic material particles from agglomerating and allowing them to easily exit the process apparatus.

Within the scope of the above mentioned aim, a main object of the present invention is to provide such a device which is specifically designed for application to pressurized system, thereby providing plastic material processing systems very simple from a construction standpoint and very efficient from an operating standpoint.

Another object of the present invention is to provide such an astatic or antistatic system which, owing to its specifically designed features, is very reliable and safe in operation.

Yet another object of the present invention is to provide such an astatic device, specifically designed for removing electrostatic charges on plastic material ground particles and powders, stored in storing hoppers and silos, for preventing said plastic material particles from agglomerating, thereby allowing said plastic material to easily exit the storing hoppers and silos.

Yet another object of the present invention is to provide such an astatic system for pressurized reactors and cyclones for processing plastic materials and, in particular, for polymerizing olefines, which can be easily made starting from easily available elements and materials and which, moreover, is very competitive from a mere economic standpoint.

According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by an astatic system for pressurized reactors and cyclones for processing plastic materials in general and, in particular, for polymerizing olefines, characterized in that said system comprises an astatic bar to be applied inside a reactor and cyclone vessel and having an inner insulating body therewith are associated a plurality of pointed elements capacitively coupled to a conductor covered by a dielectric material and housed in said insulating body.

Said conductor tightly projects from said vessel body, and can be coupled to a high voltage power supply.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more apparent hereinafter from the following detailed disclosure of a preferred, though not exclusive, embodiment of an astatic device for pressurized reactors and cyclones, and being illustrated by way of an indicative, but not limitative, example with reference to the accompanying drawings , where :

Figure 1 is a schematic cross-sectional view illustrating the astatic system according to the invention; Figure 2 is an exploded view illustrating the astatic system according to the invention, and clearly showing a bell vessel thereof;

Figure 3 illustrates an astatic bar or rod; Figures 4, 5, 6, 7 and 8 show different possible embodiments of the cross-section of said astatic bar or rod, depending on the type and number of the used pointed elements;

Figure 9 illustrates an astatic bar coated by a resin material; Figure 10 is a cross-sectional view, substantially taken along the section line X-X of Figure 9 ;

Figure 11 is a schematic cross-sectional view illustrating the throughgoing double connector; Figure 12 is a side elevation view, on an enlarged scale, illustrating the astatic bar or rod;

Figure 13 is a schematic view illustrating a possible cross-section of a variation of the astatic bar;

Figures 14 to 18 illustrates other possible cross-sections of the astatic bar; Figure 19 is an axial cross-sectional view, illustrating a flange for supporting an astatic bar;

Figure 20 is a front elevation view illustrating the supporting flange shown in Figure 19;

Figure 21 is a schematic view illustrating the supporting flange of Figure 20, the astatic bar being shown in cross section according to one of its possible configurations;

Figure 22 shows the astatic bar held inside a hopper; Figure 23 illustrates that same astatic bar, held inside another storing hopper; and

Figure 24 illustrates that same astatic bar arranged inside a storing silo.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the number references of the above mentioned figures, the astatic device for pressurized reactors and cyclones for processing plastic materials in general and, in particular, for polymerizing olefines, according to the present invention, which has been generally indicated by the reference number 1, comprises an astatic bar 2, which will be disclosed in a more detailed manner hereinafter.

Said astatic bar or rod is coupled to a bell-shape body 3, which can be coupled to the vessel body 4 of a reactor or cyclone for allowing an electric conductor or cable to tightly exit said body.

More specifically, the bell body 3 is provided with a flange 10, associated with the barrel of the bell body and which, by a counter- flange 11 is coupled to a further flange 12 applied to the vessel

4.

The bell body 3 defines a flange 15 for coupling to a recycling circuit for recycling possible inflammable gases, as well as an attachment 16 for control and safety devices .

The system further comprises a throughgoing double connector 20, clearly shown in Figure 11, allowing a high voltage cable 21 coupled to the throughgoing bar 2 to exit the reactor vessel 4.

Said bar 2, as clearly shown in Figure 3, is provided with an attachment body 30 (an insulating material flanged connector) , to which is coupled a cap

31 for locking the high voltage electric conductor protecting sheath 32.

The bar 2 is provided with a perforated bar element 33, in which is provided a fiberglass pipe 34 providing an insulating body including in its inside the mentioned conductor 21. The latter is coated by a dielectric layer

35, to provide a capacitive type of coupling.

On the inner insulating body 34 are provided a plurality of pointed elements 36, which can be arranged according to any suitable desired arrangement , and which can be provided in a number of

1 to 4, with any desired angular arrangement.

It is moreover possible to provide a resin coated bar, generally indicated by the reference number 2' and shown in Figure 9, having an outer body 40 including an opening 41 affecting a portion of the longitudinal extension in a region where said pointed elements, also indicated by 36, are provided.

At its inner end portion, said bar is coupled to the bell body and the high voltage conductor projects therefrom through the double connector 20 which, as shown in Figure 11, is provided, at the two end portions thereof, with a male connector 50, holding the conductor 21 and being coupled to an inner pipe 51 enclosing therein a copper filament or wire 52.

The latter connects the pins 53 arranged at the end of the pipe 51 and being operatively coupled to the male connectors 50.

A ring nut 55 adapted to provide a wall fixing region at the top part of the bell body is moreover provided. With the disclosed arrangement, the antistatic bar arranged inside the vessel body will provide a potential difference between the pointed elements thereof, with respect to the ground, which will be very high thereby ionizing the hydrocarbon gas generally present in said vessel body.

In particular, the hydrocarbon gas atoms will be decomposed into three electrons, i.e. negative ions, and positive free nuclei, i.e. positive ions.

Since opposite charges tend to attract, the positively charged plastic material particles, by passing through said ionized hydrocarbon gas, will attract negative free ions, to be neutralized thereby, whereas the negatively charged particles will attract the positive free ions, to be also neutralized.

Thus, the electrostatically charged particles will be prevented from agglomerating to one another, thereby allowing the system to operate in an optimum manner.

In a further embodiment, shown in Figure 12 and in the following figures, the astatic device according to the present invention substantially comprises an astatic bar or rod, generally indicated by the reference number 61, which is provided with an insulating material central body 62 in which are arranged a plurality of pointed elements capacitively coupled to an inner conductor cable 80. The latter is coated by an insulating sheath

81, arranged inside said central body 62.

Said central body 62, in turn, is encompassed, by a nickel plated brass pipe 64, and being perforated at 180° or at 360°. The mentioned astatic bar 61 is provided, at least at one of the axial end portions thereof, with a flange 65 provided for supporting the astatic bar 61 in a storing hopper 66a and 66b, as shown in Figures 22 and 23, or in a storing silo 67, as shown in Figure 24.

The pointed element 63 in the central insulating body of the astatic bar 61 can be arranged in a row extending longitudinally along an insulated conductor 80 of said astatic bar 61, or they can be arranged with a two-row arrangement, the rows of which are angularly offset from one another about the axis of the astatic bar, with an angle of substantially 90°, as is shown in Figures 13, 14 and 21.

As shown in Figure 16, the pointed elements 63 arranged in the insulating central body 62 of the astatic bar or rod 61 can also be arranged in two longitudinal rows which are angularly offset from one another about the axis of said astatic bar 61 with an angle of substantially 180°.

As shown in Figure 17, the pointed elements 63 in said central body 62 of said astatic bar 61 can also be arranged in three longitudinal rows, which are angularly offset from one another about the axis of the astatic bar 61, according two angles of 90° and an angle of 180° .

As shown in Figure 18, the pointed elements 63 in said central insulating body 62 of said astatic bar 61 can also be arranged in four longitudinal rows, angularly offset from one another, about the longitudinal axis of said astatic bar, according to four angles of 90°. Said flange 65 comprises moreover a plurality of holes 68 which can be used for clamping, by clamping bolts or other suitable coupling means, the astatic bar 61 to the casing of the storing hopper 66a, 66b or silo 67. The conductor 80 is coated by a special dielectric material 81, arranged in said insulating central body 62 of said astatic bar, and is coupled to a high voltage power supply 70 having preferably a primary voltage of 230 V and a primary current of 50/100 mA with a frequency of 50/60 Hertz and a secondary voltage on said conductor 21 preferably from 6,750 V to 7,000 V, with a short current intensity through the two arms coupled to said conductor 21 substantially from 1-1.5 to 2.5 mA.

The connection of the bar to the high voltage power supply 70 is performed by a special neon cable 71, for example a silicone or other equivalent material cable.

Said cable 71 is coated by a special silicone insulating sheath or by an insulating sheath made of any other suitable material . The astatic device according to the invention operates as follows: the astatic bar 61 arranged in a storing hopper 66a and 66b or in a storing silo 67 will have a very high voltage or potential difference between the pointed elements thereof, with respect to the ground, thereby ionizing the air in the storing hopper 66a and 66b or silo 67.

Thus, the air or gas atoms will be decomposed into free electrons (negative ions) and positive free nuclei (positive ions) . Since opposite charges tend to attract, the positively charged plastic material particles, powders and the like, by passing through the ionized air or gas, will attract the negative free ions to be neutralized thereby, whereas the negatively charged plastic material particles and the like, will attract the positive free ions thereby being also neutralized.

Thus, the charged particles will be prevented from agglomerating (bridging effect) , thereby said plastic material particles can be easily removed from the storing hoppers 66a, 66b and silos 67, to provide a continuous even type of operation.

From the above disclosure it should be apparent that the invention fully achieves the intended aim and objects.

In particular, it is to be pointed out that the disclosed astatic system is very suitable for application to pressurized reactors, owing to the provision of the bell body and double connector providing very good sealing properties.

The invention, as disclosed, is susceptible to several modifications and variations all of which will come within the scope of the invention.

Moreover, all the constructional details can be replaced by other technically equivalent elements.

In practicing the invention, the used materials, as well as the contingent size and shapes, can be any, depending on the requirements.

Claims

1. An astatic device for pressurized reactors and cyclones for processing plastic materials in general and, in particular, for polymerizing olefines, characterized in that said device comprises an astatic bar adapted to be applied in a reactor or cyclone vessel body and having an inner insulating body, therewith are associated a plurality of pointed elements capacitively coupled to a conductor covered by a dielectric material and arranged in said insulating body, said conductor projecting from said vessel body and being adapted to be coupled to a high voltage power supply.

2. An astatic device, according to the preceding claim, characterized in that said antistatic bar is coupled to a bell-shape body provided with a flange which, through a counter flange, is coupled to a further flange applied to the outer walls of said vessel body.

3. An astatic device, according to the preceding claims, characterized in that said bell- shape body is provided with a recycle flange for recycling possible inflammable gases to be removed.

4. An astatic device, according to one or more of the preceding claims, characterized in that said bell-shape body comprises an attachment for control and safety devices .

5. An astatic device, according to one or more of the preceding claims, characterized in that on said bell-shape body is coupled a throughgoing double connector, for allowing a high voltage conductor to pass therethrough.

6. An astatic device, according to one or more of the preceding claims, characterized in that said astatic bar is provided, at one end portion thereof, with a cap for locking a protective sheath of said conductor.

7. An astatic device, according to one or more of the preceding claims, characterized in that said astatic bar is provided with a perforated body, wherein the inner insulating body is made of a fiberglass inner pipe in which a conductor coated by an insulating dielectric layer is arranged.

8. An astatic device, according to one or more of the preceding claims, characterized in that said inner insulating body supports a row of pointed elements .

9. An astatic device, according to one or more of the preceding claims, characterized in that said inner insulating body supports two rows of pointed elements which are variously angularly distributed.

10. An astatic device, according to one or more of the preceding claims, characterized in that said inner insulating body supports three rows of pointed elements which are variously angularly distributed.

11. An astatic device, according to one or more of the preceding claims, characterized in that said inner insulating body supports four rows of pointed elements.

12. An astatic device, according to one or more of the preceding claims, characterized in that said device comprises moreover a resin coated astatic bar which is provided, about said insulating body, with a resin cast coating affecting a portion of a circumferential extension of said inner insulating body, said pointed elements being provided in said portion.

13. An astatic device, according to one or more of the preceding claims, characterized in that said throughgoing double connector is provided with a pair of male connectors coupled, by pins, to an inner pipe; in said inner pipe being arranged a copper filament for coupling the conductors coupled to said male connectors; said throughgoing double connector being associated with a ring-nut for locking said connector to a wall of said bell-shape body.

14. An astatic device, according to one or more of the preceding claims, adapted to be used for removing electrostatic charges on plastic material particles and the like, arranged in storing hoppers and silos, characterized in that said device comprises an astatic bar having an inner insulating body in which are arranged a plurality of pointed elements, capacitively coupled to a conductor coated by a special dielectric material and that said bar is supplied with a high voltage by a high voltage power supply, said astatic bar being provided, at least at one of the axial end portions thereof, with a flange for supporting said bar in said storing hoppers or silos .

15. An astatic device, according to one or more of the preceding claims, characterized in that said pointed elements arranged in said insulating material central body are capacitively coupled to the insulated conductor arranged in said insulating body and are arranged along a row longitudinally extending along said astatic bar.

16. An astatic device, according to one or more of the preceding claims, characterized in that said pointed elements arranged in said insulating material central body are arranged along two longitudinal rows angularly offset from one another, about an axis of said astatic bar, according to an angle of 90° .

17. An astatic device, according to one or more of the preceding claims, characterized in that said pointed elements arranged in said insulating material central body are arranged along two longitudinal rows angularly offset from one another about an axis of said astatic bar, according to an angle of 180°.

18. An astatic device, according to one or more of the preceding claims, characterized in that said pointed elements, arranged in said insulating material central body, are arranged along three longitudnal rows and are angularly offset from one another about an axis of said astatic bar, according two angles of 90° and an angle of 180°.

19. An astatic device, according to one or more of the preceding claims, characterized in that said pointed elements arranged in said insulating material central body are arranged along four longitudinal rows and are angularly offset from one another about an axis of said astatic bar according to four angles of 90°.

20. An astatic device, according to one or more of the preceding claims, characterized in that said astatic bar is coupled to said high voltage power supply by a neon cable .

21. An astatic device, according to one or more of the preceding claims, characterized in that said astatic bar is coupled to said high voltage power supply by a silicone cable or by any other special types of cables.

22. An astatic device, according to one or more of the preceding claims, characterized in that said cable is coated by a silicone or the like material insulating sheath.

23. An astatic device, according to one or more of the preceding claims, characterized in that a chromium or nickel plated brass pipe is arranged about said insulating material central body, said brass pipe being perforated at 180°, 270° or 360 _\'o

AMENDED CLAIMS

[received by the International Bureau on 20 October 2000 (20.10.00); original claims 1-23 replaced by new claims 1-21 (4 pages)]

1. An astatic device for pressurized reactors and cyclones for processing plastic materials in general and, in particular, for polymerizing olefines, comprising an astatic bar adapted to be applied in a reactor or cyclone vessel body, characterized in that said astatic bar has an inner insulating body, therewith are associated a plurality of pointed elements capacitively coupled to a conductor covered by a dielectric material and arranged in said insulating body, said conductor projecting from said vessel body and being adapted to be coupled to a high voltage power supply, that said antistatic bar is coupled to a bell-shape body provided with a flange which, through a counter flange, is coupled to a further flange applied to the outer walls of said vessel body, and that said bell- shape body is provided with a recycle flange for recycling possible inflammable gases to be removed.

2. An astatic device, according to Claim 1, characterized in that said bell-shape body comprises an attachment for control and safety devices.

3. An astatic device, according to Claims 1 and 2, characterized in that on said bell-shape body is coupled a throughgoing double connector, for allowing a high voltage conductor to pass therethrough.

4. An astatic device, according to Claim 1, characterized in that said astatic bar is provided, at one end portion thereof, with a cap for locking a protective sheath of said conductor.

5. An astatic device, according to Claim 1, characterized in that said astatic bar is provided with a perforated body, wherein the inner insulating body is made of a fiberglass inner pipe in which a conductor coated by an insulating dielectric layer is arranged.

6. An astatic device, according to Claim 1, characterized in that said inner insulating body supports a row of pointed elements .

7. An astatic device, according to Claim 1, characterized in that said inner insulating body supports two rows of pointed elements which are variously angularly distributed.

8. An astatic device, according to Claim 1, characterized in that said inner insulating body supports three rows of pointed elements which are variously angularly distributed.

9. An astatic device, according to Claim 1, characterized in that said inner insulating body supports four rows of pointed elements .

10. An astatic device, according to Claim 1, characterized in that said astatic bar is a resin coated astatic bar which is provided, about said insulating body, with a resin cast coating affecting a portion of a circumferential extension of said inner insulating body, said pointed elements being provided in said portion.

11. An astatic device, according to Claims 1 to 10, characterized in that said throughgoing double connector is provided with a pair of male connectors coupled, by pins, to an inner pipe; in said inner pipe being arranged a copper filament for coupling the conductors coupled to said male connectors; said throughgoing double connector being associated with a ring-nut for locking said connector to a wall of said bell-shape body.

12. An astatic device, according to Claims 1 to 11, adapted to be used for removing electrostatic charges on plastic material particles and the like, arranged in storing hoppers and silos, characterized in that said device comprises an astatic bar having an inner insulating body in which are arranged a plurality of pointed elements, capacitively coupled to a conductor coated by a special dielectric material and that said bar is supplied with a high voltage by a high voltage power supply, said astatic bar being provided, at least at one of the axial end portions thereof, with a flange for supporting said bar in said storing hoppers or silos.

13. An astatic device, according to Claims 1 to 12, characterized in that said pointed elements arranged in said insulating material central body are capacitively coupled to the insulated conductor arranged in said insulating body and are arranged along a row longitudinally extending along said astatic bar.

14. An astatic device, according to Claims 1 to 13, characterized in that said pointed elements arranged in said insulating material central body are arranged along two longitudinal rows angularly offset from one another, about an axis of said astatic bar, according to an angle of 90°.

15. An astatic device, according to Claims 1 to 14, characterized in that said pointed elements arranged in said insulating material central body are arranged along two longitudinal rows angularly offset from one another about an axis of said astatic bar, according to an angle of 180°.

16. An astatic device, according to Claims 1 to 15, characterized in that said pointed elements, arranged in said insulating material central body, are arranged along three longitudinal rows and are angularly offset from one another about an axis of said astatic bar, according two angles of 90° and an angle of 180° .

17. An astatic device, according to Claims 1 to 16, characterized in that said pointed elements arranged in said insulating material central body are arranged along four longitudinal rows and are angularly offset from one another about an axis of said astatic bar according to four angles of 90°.

18. An astatic device, according to Claims 1 to 17, characterized in that said astatic bar is coupled to said high voltage power supply by a neon cable.

19. An astatic device, according to Claims 1 to 18, characterized in that said astatic bar is coupled to said high voltage power supply by a silicone cable or by any other special types of cables .

20. An astatic device, according to Claim 19, characterized in that said cable is coated by a silicone or the like material insulating sheath.

21. An astatic device, according to claims 1 to 20, characterized in that a chromium or nickel plated brass pipe is arranged about said insulating material central body, said brass pipe being perforated at 180°, 270° or 360°.