ES2345674T3 - DEVICE AND INSTALLATION TO ELIMINATE POWDER FROM GRANULAR MATERIALS. - Google Patents

Abstract

The present invention relates to a dust removing device for granular material comprising: a casing (2) delimiting a supply chamber (3) arranged to feed granular material to be freed from dust, and being formed with an input opening (3a); a dust removing chamber (4) designed to remove dust from the granular material and in fluid communication with the supply chamber (3); a disposing chamber (5) for granular material freed from dust formed with an output opening (5a), thereby allowing an uninterrupted flow of granular material to be freed from dust to occur between the supply chamber (3) and the disposing chamber (5); a pressurized washing air supply opening (5b); and a washing air discharging duct (14); a source (12) of pressurized air; a delivery duct (13) between the pressurized air source (12) and the pressurized air supply opening (5b); a return piping (17) between the washing air discharging duct (14) and the washing air source (12); one or more filters (16) in the return piping; and fluidifying fluid (6) for the granular material to be freed from dust located in the dust removing chamber (5), and conveying and dosing arrangment (11, 11a) designed to convey and meter the granular material to be freed from dust and located between the supply chamber (3) and the dust removing chamber (5).

Description

Device and installation to remove dust from granular materials

The present invention relates to a device and installation to remove agents pollutants, typically dust, of granular materials, particularly plastic granular materials.

In the field of the transformation process of plastic materials, the raw material usually has the form of granules, this being the most suitable way for transport and storage in containers of different dimensions, e.g. ex. silos and hoppers, as well as for any transformation process in each process stage such as dehumidification and mixed preceding the molding in an injection press.

Typically, the plastic granular material is stored in bags of 25 liters in the case of quantities relatively small, or in 100 liter bags or in silos when It works with large quantities. The plastic granular material is removed from storage, usually through conventional pneumatic transport systems, to be supplied to processing or processing machines, such as injection presses and / or extruders.

During transport from the place of storage to a processing machine, the material granular is subject to the risk of being contaminated by various external agents

First, the material granules plastic can be mixed with dust and / or other pollutants,  that are present almost permanently in the atmosphere of work, with the consequent risk to the granular material, and therefore the molded objects obtained from them they can be contaminated too, often resulting in combination in property deterioration Physicochemical of molded material.

Additionally, during material handling, plastic granular material may be subject to stress substantial thermal or mechanical, p. ex. due to friction while being pneumatically transported, which can result in the detachment of particles in the form of powder granules which are added to the amount of dust already present in the mass of the granular material. Dust particles formed in this way they are, so to speak, a "deteriorated" form of the material of polymer, that is to say its properties physicochemical, p. ex. its temperature of softening, its viscosity and the like, are often very different from those of the plastic material from which they originated. Neither that has to say that the presence of said dust particles in the final molded product is undesirable, since it affects the technical characteristics of it.

The problems due to the presence of Pollutant dust particles in plastic materials granules then become particularly serious when they have to get molded objects or products with high purity characteristics, that is products in which it cannot found any defect or manufacturing failure, such as by example medical devices, or products with features optics, p. ex. Lenses or lamps.

Various systems to eliminate dust contaminant of granular materials, called "dust separators" have been proposed in the past and are currently available in the market, which are installed usually upstream of a transformation machine.

Such dust separators are a component of a dust separator installation and consist of one or more slanted grilles on which gravity falls a granular material to be treated, that is to say from which the dust particles Due to the impact against the grid, or grilles, dust particles are separated from the granular material, and then they keep floating and move away from the granular material through a flow of what is called cleaning air, injected through the grilles. Then the air flow rate of cleaning, loaded with dust particles, for possibly recycle it back to the dust separator facility while that dust particles thus separated from the cleaning air are accumulate in a suitable container.

A dust separator according to the preamble of claim 1 is also known by the WO 2004/048006, said powder separator comprising a fluidization medium for the granular material.

To make dust separation easier from a granular material, sometimes an unloading apparatus is provided of electric charges upstream of the separating installation of dust, whose function is to destroy or weaken any force of electrical bond between the dust particles and the granules of plastic material.

Dust separating facilities traditional, although satisfactory from certain points of view, They are affected by a number of serious disadvantages.

First, they are essentially devices static, and therefore require an additional control system for the flow of granular material, to avoid obstructions caused by the excessive accumulation of the granules to be supplied to the fixed grilles, which would result in a reduction in the efficiency of decontamination or dust separation.

Additionally, as mentioned previously, the granular material to be decontaminated is dropped on a plurality of grids, typically two or three grids, and therefore the air flow designed to float and move away Pollutant dust particles flows directly through a plurality of static strangulation elements, with the consequent relevant pressure losses. Therefore you are Dust separating installations require an air flow of high input with consequent high energy consumption.

There is, therefore, the need for a proper dust separator installation to eliminate or reduce drastically the aforementioned disadvantages mentioned With the current state of the art.

The main objective of the present invention is to provide a type dust separator installation dynamic that is suitable for fluidizing the granular material to separate, thus helping to promote collisions between the granules, and therefore to separate any agent from the granules Pollutant in the form of dust.

Another objective of the present invention is provide a dust separator installation that includes a Dosing system for dosing a granular material at decontaminate dust, to obtain a constant output flow and controlled dust-free material.

A further objective of the present invention is to provide a dust separator installation that includes a plurality of dust separating devices, as well as a procedure to supply controlled air of cleaning to these devices.

A no less important objective of the present invention is to provide a dust separator installation that It can be manufactured at a competitive cost, and also simple to install even in transport and processing facilities Pre-existing for plastic materials.

In accordance with a first aspect of the present invention, a dust separator device is provided for granular material, which comprises:

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a cover that delimits a supply chamber arranged to supply a granular material from which the dust, and that is formed with an inlet opening; a camera dust separator designed to separate dust from material granular and in fluidic communication with said supply chamber; a distribution chamber for dust-free granular material formed with an outlet opening, therefore allowing between said supply chamber and said distribution chamber produce an uninterrupted flow of granular material of which there is that eliminate dust; an air supply opening of pressure cleaning; and an air discharge duct of cleaning;

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a pressurized air source;

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a supply duct between said source of pressurized air and said air supply opening;

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a return line between said air discharge duct of cleaning and said source of cleaning air; Y

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a filter medium in said return pipe.

additionally comprising the device powder separator a fluidizing medium for the material granular from which the dust must be removed, located in the chamber dust separator, and means of transport and dosage designed to transport and measure the granular material of which there is that remove dust, and that are located between the chamber of supply and dust separator chamber.

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In accordance with another aspect of this invention, a dust separator installation is provided, the which includes:

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a plurality of the mentioned dust separating devices previously;

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to the less a source of pressurized cleaning air;

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a common pressurized cleaning air supply pipe that extends from said at least one source to each device dust separator;

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a common cleaning air return pipe extending from each dust separating device up to said at least one source;

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to the minus a filter medium in said common return pipe,

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said separating devices being of powder of said plurality of dust separating devices connected in parallel between said common supply pipe and said common return pipe; Y

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a programmable electronic control unit, common, designed to control said at least one source of pressurized air and each of said dust separating devices.

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Certain features and additional advantages of the present invention will become apparent from the following detailed description of the achievements currently preferred thereof, offered by non-limiting examples and indicative, with reference to the attached drawings, in the which:

Figure 1 is a perspective view, partially in cross section, of a separating device of powder according to the present invention;

Figure 2 is a front view, partially in cross section, of the dust separating device of the Claim 1, which includes an air supply system, filtering, and distribution for cleaning air;

Figure 3 shows a schematic view of a realization of a dust separator installation that includes four dust separating devices of Figures 1 and 2.

In the attached drawings the same portions and components, or the like, have been labeled with the same numbers reference.

Referring first to Figures 1 and 2, a dust separator device, indicated generically with the numerical reference 1, includes an external housing or cover 2, in which are delimited three cameras, that is a camera 3 of supply or supply of granular material, a chamber intermediate 4 to separate or clean the dust from a material granular supplied from chamber 3, and a chamber 5 of distribution to download the granular material free of powder.

More precisely, the supply chamber 3 it has a top entry opening 3a, typically in fluidic communication, p. ex. by fall, with a hopper (no represented in the drawings) that stores granular material and is communicates through a lower and lateral portion thereof with intermediate chamber 4 decontamination. Chamber 5 of distribution is located downstream of the separator chamber 4 of dust, and is in direct communication with it and has a bottom opening 5a for the granular material free of powder, which is usually in fluidic communication with a transformation machine (not shown in the drawings), p. ex. an injection press of any suitable type. A half of fluidization, e.g. ex. a sieve 6 having a lateral surface foraminated, preferably cylindrical and manufactured with stainless steel plate, is located in intermediate chamber 4 dust separator. Screen 6 is designed to receive a granular material to be decontaminated from the supply chamber 3 and to download it, dust free, in the output chamber 5.

To this end, sieve 6, in use, is mounted to rotate with respect to a substantially horizontal axis and can be rotated by a drive shaft 7 controlled by a means motor of any suitable type, e.g. ex. a gearmotor 8 electrically connected to an electronic control unit programmable CU. The gearmotor 8 is preferably located outside deck 2, p. ex. adjacent to supply chamber 3  whose side surface 3b has in this case a hole 9 through which the drive shaft 7 extends, the seal being sealed hole 9 around drive shaft 7 by means of retainer suitable, p. ex. a felt ring 10, to prevent leaks from granular material from the device 1 dust separator.

Preferably, the drive shaft 7 extends to through the three chambers 3, 4 and 5 and one end of it is operatively connected to, and is supported by, the gearmotor 8 outside the supply chamber 3, and its other end is rotatably mounted on deck 2, in chamber 5 of discharge.

In a section of the drive shaft 7 which extends between the supply chamber 3 and the dust separator chamber 4, the drive shaft supports, or is integral with, a dosing medium and transport, p. ex. a means of transport such as a screw motorized 11 surrounded by a corresponding working duct 11a which also extends from the supply chamber 3 to the chamber 4 dust separator. Such screw 11, with its corresponding work duct 11a, constitutes a system volumetric dispenser and conveyor arranged for measure and transport the granular material between the two chambers 3 and 4. Its dimensions are such that, for each rotation of the drive shaft 7, and therefore of screw 11, a predetermined amount of granular material is transported from the supply chamber 3 to chamber 4, or more precisely to screen 6 located in the same.

From a constructive point of view, sieve 6 it has a partition 6a near the supply chamber 3, through from which a terminal section of the working duct 11a of screw 11, and can be secured advantageously to the drive shaft 7 by two portions in the form of cross, 6b and 6c, arranged to support axis 7 and follow it in its rotation, so that the sieve rotates rigidly with the drive shaft 7. More particularly, there is a material collection area granular supplied and dosed by screw 11, delimited between the partition 6a and the support portion 6b. The granules are move from the collection or collection area to the area of dust separation between the two support portions 6b and 6c, in where due to the rotation of sieve 6, the granular material is fluidizes, resulting in an increase in collisions between the granules and in the separation of any dust agent pollutant. Finally, the dust-free granular material is moves to the support part 6c of the distribution chamber 5 or discharge, from which it is supplied to a machine downstream transformation.

Therefore, while maintaining a speed constant rotation of the gearmotor 8, a flow rate will be maintained granular material constant through device 1 separator of dust

In the discharge chamber 5, the cover 2 has an inlet opening 5b through which air is supplied for cleaning by means of an air transport duct 13 of cleaning, from a source of pressurized cleaning air, p. ex. a compressor 12 electrically connected to the control unit programmable CU.

The air entering the separator device 1 of dust through the opening 5b flows through the granular material to the time this is fluidized in sieve 6, and captures any particle of contaminating dust in it and then flow to through the foraminated partition of the sieve 6 to a pipe 14 of discharge, which is in fluidic communication with a pipe 15 suction

Advantageously, the entrance opening 5b of air is located downstream of intermediate chamber 4 separator of dust, and the discharge pipe 14 is located substantially upstream, so that the cleaning air is supplied to against current with respect to the granular material to be decontaminated. Cleaning air loaded with dust particles is filtered by a filter 16 of any suitable type, which is located in a cleaning air return duct 17, and then is recycled in the dust separator device.

The device 1 dust separator, in the inlet opening 3a of the material supply chamber 3 granular, comprises a charge neutralization unit 18 electrostatic designed to neutralize any binding load electrostatic between granules and dust particles transported by them. Such neutralization unit 18 comprises a high voltage generator 19, typically a generator AC voltage of 4-7 kV, which is connected electrically to the CU control unit and feeds one or more points 20 ionization located inside a sleeve 21. Air is injected compressed through a conduit 22, and while flowing near the ionization point or points 20 is ionized, and then found with the granular material that is entering the device 1 Dust separator through inlet opening 3a. Ions positive ionized air neutralizes positive charges, while negative ions neutralize positive charges, of the granular input material.

Due to the neutralization of charges electrostatic, the bonding forces between the granules of material  plastic and dust particles are destroyed, which helps to the subsequent dust separation operation.

In another embodiment, not represented in the drawings, of the device 1 dust separator, unit 18 of neutralization of electrostatic charges may be located in the opening 5b for cleaning chamber air inlet 5. In such case, the cleaning air entering the sieve 6 will be ionized directly without the need to supply additional compressed air to the device 1 dust separator, and the neutralization of the electrostatic charges on the granules, with the consequent separation of the dust particles from the granules, will take place inside the sieve 6.

The granular material, now free of particles of polluting dust, flows to the distribution chamber 5 and then it falls, due to gravity, on an extreme portion 5c of the distribution chamber from which it is supplied to a machine downstream processing.

Advantageously, in the extreme portion 5c it provides a level control means, e.g. ex. a sensor capacitive 23 that is electrically connected to the unit programmable electronic control CU. When the material level dust-free granular in the end portion 5c of the chamber 5 of distribution falls below a predetermined level, the sensor capacitive 23 sends a signal to the control unit CU which, at in turn, energizes the device 1 dust separator, more particularly the gearmotor 8, the compressor 12 and the unit 18 of neutralization of electrostatic charges, to restore the level of dust-free material in the extreme portion 5c.

As shown in Figure 2, the device 1 dust separator according to the present invention comprises a return valve 24 which is located between the discharge conduit 14 and the suction conduit 15 of cleaning air Such return valve 24 comprises a body 25 of the valve, within which a sealing element can move 26, the sealing element being controlled by a driving means of any suitable type, preferably a pneumatic drive means, p. ex. a piston and cylinder unit 27 controlled by the unit CU control and designed to open / close a passage between the duct 14 discharge and the air suction duct 15.

In general, in a processing facility of granular plastic materials a plurality are provided of dust separating devices. A separating installation of powder, according to the embodiment shown in Figure 3, It comprises four dust separating devices 101, 102, 103, 104, which are connected in parallel by means of bypass inputs 101a, 102a, 103a, 104a and outputs at bypass 101b, 102b, 103b, 104b for pressurized air, which are located between a common supply conduit 130, designed to supply cleaning air supplied by a compressor 120, and a common return duct 170 for the cleaning air, the which is intercepted by a filter 160. The separator installation of powder comprises a single compressor 120 and a single filter 160 to reduce both the overall dimensions and the costs of handling and maintenance Preferably, the operation of the four 101, 102, 103 and 104 dust separating devices and compressor 120 is controlled by the electronic control unit Common programmable CCU.

Normally, in a separating installation of powder provided with a plurality of separating devices of powder, of the type shown in Figure 3, rarely operate simultaneously all devices, and therefore the compressor 120 and filter 160 are sized to generate and filter an amount of pressurized cleaning air that is enough to supply only a given amount of dust separating devices. Therefore, the air must circulate only when the device (s) dust separator / s require it / n.

More particularly, the embodiment shown in Figure 3 is illustrated with its separating devices of powder 101 and 102 in operational or active condition, while dust separating devices 103 and 104 are in a configuration stopped or inactive. The CCU control unit detects the active / inactive condition of the four separating devices of powder 101, 102, 103, 104 checking the filling condition of the distribution chamber 51, 52, 53, 54 of each device, being each filling condition detected by a respective sensor level 231, 232, 233, 234, and then controls the air supply of pressurized cleaning of active devices 101 and 102, respectively, and the corresponding opening of the valves return 243, 244. The CCU also controls the closing of the valves of return of inactive dust separating devices 103 and 104, respectively.

In case it is necessary to rid the dust of granular material by device 103, such device it can be switched between its non-operative condition and its condition operational The CCU control unit detects the change in status of the device 103 dust separator and wait until one of the active devices, e.g. ex. device 102 has been switched between its operational state and its non-operational state. In this point, the CCU control unit causes the return valve 242 of the device 102 (which is not operational now) closes, and makes than the return valve 243 of the device 103 (which now is in operational state) open simultaneously.

In the particular case that in an installation dust separator, provided with a plurality of devices dust separators, only one or a small number of said devices are in their active condition, any amount of air generated and managed by compressor 120 is supplied to said dust separator device. This condition is not desirable. since such excessive air flow would interfere with the flow of granular material through the dust separator device as well as with the fluidization inside sieve 6. To overcome such inconvenient, a bypass valve 150 is provided in the supply conduit 130, the valve 150 being connected electrically to the CCU control unit and being designed to divert excess air flow supplied by the compressor 120.

The present invention, as described previously, it is susceptible to numerous modifications and variations within its protected scope, as defined in The claims.

Claims (20)

1. A dust separator device for granular material, comprising:

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a cover (2) delimiting a supply chamber (3) arranged to supply a granular material to which we must get rid of powder, and which is formed with an inlet opening (3a); a dust separator chamber (4) designed to separate dust from granular material and in fluid communication with said chamber (3) of supply; a distribution chamber (5) for granular material dust free formed with an outlet opening (5a), allowing therefore an uninterrupted flow of granular material, to which it is necessary to get rid of dust, between said supply chamber (3) and said distribution chamber (5); a supply opening (5b) pressurized cleaning air; and a discharge duct (14) of cleaning air;

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a source (12) of pressurized air;

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a supply duct (13) between said air source (12) pressurized and said air supply opening (5b);

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a return pipe (17) between said discharge duct (14) of cleaning air and said source (12) of cleaning air; Y

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a filter medium (16) in said return pipe, and a means (6) of fluidization for said granular material, which must be rid of dust, in said chamber (5) dust separator,

characterized in that it comprises means for transporting and dosing (11, 11a) designed to transport and measure said granular material to which dust must be removed and which are located between the supply chamber (3) and said dust separator chamber (5) .

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2. A device as claimed in claim 1, characterized in that said fluidizing means comprises a sieve element (6) mounted for rotation in the dust separating chamber (4), and a driving means for said sieve element ( 6). A device as claimed in Claim 2, characterized in that said sieve element (6) comprises a partition (6a) disposed upstream of said uninterrupted flow near said supply chamber (3), and at least a portion ( 6b, 6c) support to drag it in its rotation. 4. A device as claimed in claims 2 or 3, characterized in that said drive means comprises a gearmotor unit (8). 5. A device as claimed in any preceding claim, characterized in that said means of transport and dosage comprises at least one conveyor means. A device as claimed in Claim 5, characterized in that said at least one conveyor means comprises a motorized screw (11) and a respective working duct (11a). A device as claimed in Claim 6, insofar as it depends on Claim 3, characterized in that said working duct (11a) of said at least one conveyor means extends through said partition (6a) to said chamber ( 7) dust separator and is hermetically sealed with respect to said partition. A device as claimed in Claim 6 or 7, characterized in that said at least one screw conveyor means (11, 11a) rotates rigidly with said sieve unit (6). A device as claimed in any preceding claim, characterized in that said air supply opening (5b) is located downstream of said dust separating chamber (4) and said discharge duct (14) is located substantially upstream of said dust separator chamber (4), whereby the cleaning air is supplied countercurrent with respect to the material to be released from dust in said dust separator chamber (4). 10. A device as claimed in any preceding claim, characterized in that it comprises a programmable electronic control unit (CU). A device as claimed in any preceding claim, characterized in that it comprises an electrostatic charge neutralization unit (18) controlled by said programmable electronic control unit (CU).

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A device as claimed in Claim 11, characterized in that said electrostatic charge neutralization unit (18) comprises a high voltage generator (19) that includes at least one ionizing point (20). 13. A device as claimed in claim 11 or 12, characterized in that said neutralization unit (18) is located in said inlet opening (3a) of said supply chamber (3). 14. A device as claimed in claim 11 or 12, characterized in that said neutralization unit (18) is located in said cleaning air supply opening (5a). 15. A device as claimed in any preceding claim, characterized in that it comprises a level sensor means (23) located in said distribution chamber (5) and which is designed to send a control signal to said programmable electronic control unit (CU). 16. A device as claimed in Claim 15, characterized in that said level sensor means (23) comprises a capacitive sensor (23). 17. A device as claimed in any preceding claim, characterized in that it comprises a valve means (24) that is designed to control the flow of air through said discharge conduit (14) and that is controllable by said control unit programmable electronics (CU). 18. A device as claimed in claim 17, characterized in that said valve means (24) comprises a valve body (25), a sealing element (26), and a fluid actuated means (27) designed to control said sealing element (26). 19. A dust separator installation, characterized in that it comprises:

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a plurality of dust separating devices (101, 102, 103, 104) according to any of said plurality of devices dust separators (101, 102, 103, 104) of Claim 1 a 17, the same being connected in parallel between yes,

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to the less a source (120) of pressurized cleaning air;

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a common pipe (130) of pressurized cleaning air supply which extends from said at least one source (120) to each dust separator device (101, 102, 103, 104);

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a common pipe (170) of return cleaning air that extends from each dust separator device (101, 102, 103, 104) to said at least one source (120);

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to the minus a filter medium (160) in said return pipe (170) common,

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said devices being connected dust separators of said plurality of separating devices  of powder (101, 102, 103, 104) in parallel between said pipe (130) of common supply and said common return pipe (170); Y

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a common programmable control unit (CCU) designed to control said at least one source (120) of pressurized air and each of said dust separating devices (101, 102, 103, 104).

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20. An installation as claimed in Claim 19, characterized in that it comprises a bypass valve (150) controllable by said common programmable electronic control unit (CCU) and which is designed to divert any excess air flow supplied by said to the less a source (120) of pressurized cleaning air.