EP3491313B1

EP3491313B1 - Apparatus for drying aggregates such as sand

Info

Publication number: EP3491313B1
Application number: EP17765267.4A
Authority: EP
Inventors: Dino FEBBO
Original assignee: Walter Tosto SpA
Current assignee: Walter Tosto SpA
Priority date: 2016-07-27
Filing date: 2017-07-13
Publication date: 2020-09-02
Anticipated expiration: 2037-07-13
Also published as: WO2018020523A1; EP3491313A1; IT201600078894A1

Description

The present invention relates to an apparatus for drying aggregates, such as sand and the like, with specific application to flows for submerged arc process and/or and electroslag weldings.
More specifically, the invention concerns an apparatus or oven, specially designed and manufactured for drying the flow to be used in welding, on various types of metal materials such as cast iron, copper alloys, nickel, steel and the like, but that can be used whenever it is necessary to use sand and/or flows with a high degree of drying (in the order of a few units of ml/100g).
In the following, the description will be directed to drying the flow for weldings, but it is clear that the same should not be considered limited to this specific use.
As is well known, for carrying out optimal weldings, it is necessary to leave some flow on the junction or surfaces, for example by voltaic arc, in order to isolate the electric arc and/or the welding bath from the surrounding oxygen.
In order to obtain an optimal welding it is also necessary that the same, as soon as it is realized, is isolated from any oxidizing agents, in particular, it is desirable that said junction or plating is insulated from water and moisture.
Ovens are available in the market capable of drying inert materials, in particular sand and/or flow, intended for the purpose above. However, said ovens are not always able to dry the flow in an optimal way.
It is apparent that this procedure is expensive in terms of technical result in case of, for some applications, it is necessary to obtain a welding as perfect as possible
Documents US3938785 A and JP2011140027 A disclose different drying apparatuses. Z
In the light of the above, it is an object of the present invention to propose a drying apparatus capable of optimally drying the flow, eliminating the moisture contained therein.
Another object of the invention is to allow the flow to be dried rapidly and efficiently as well as to propose an apparatus capable of keeping the flow dry and dosing the quantities required so that it can be positioned in an automated plant.
The present invention achieves these objects by means of an apparatus according to claim 1. The dependent claims describe optional embodiments also belonging to the invention.
The present invention will be now described, for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the figures of the enclosed drawings, wherein:

figure 1 shows a first see-through perspective view of an apparatus for drying flows according to the invention;
figure 2 shows a second see-through perspective view of an apparatus according to figure 1;
figure 3 shows a see-through side view of an apparatus according to figure 1;
figure 4 shows a view along A-A section line of the apparatus according to figure 1.

In the various figures, similar parts will be indicated by the same reference numbers.
Referring to figures 1-4, it is seen an apparatus for drying inert materials 1, such as sand and the like, in particular for drying welding flows.
Said apparatus 1 essentially comprises a container 2, in which a loading unit 3, an intake unit 4, a drying unit 5 and a storage an offload unit 6 are contained.
In more detail, said container 2 has an opening 21 at the front with a relative door 22. In addition, said container 2 also has behind a compartment 23, which operation will be better defined below.
Said container 2 also includes a touch on screen type digital control panel 24', for controlling the operation of the apparatus 1, and a pushbutton 24", where there are an unload product button, an emergency mushroom and a RFID technology detection station.
Finally, said container 2 also includes wheels 25 to allow the displacement of said apparatus 1.
Said loading unit 3 comprises a loading hopper 31 driven by pneumatic actuators 32. The loading hopper 31 is accessible by opening the door 22 so that the sand or inert material to be dried can be manually loaded therein.
Said suction unit 4 comprises an aspirator 41, located in the upper portion of said apparatus 1, a suction pipe 42 (shown in figure 4), connected between said loading hopper 31 and said aspirator 41, and an outlet pipe 43.
Said aspirator 41 also includes means for controlling the level 411 of the flow contained therein, which in the embodiment of the present invention comprise a bar 412 and a detection member 413, such that when the flow in said aspirator 41 exceeds a predetermined level, said flow contacts with said detection member 413, causing the rotation of said bar 412 to stop, blocking the aspirator 41. Any other flow level detection systems may be implemented as an alternative to the described one.
Said suction unit 4 also includes a metering valve 44, arranged along said outlet pipe 43, for measuring the flow to be sent to the drying unit 5.
The drying unit 5, includes a drying drum or roller 51 having a cylindrical shape, such as to define an internal volume V, with the symmetry and rotation axis of the cylinder arranged horizontally. Said drying drum 51 is internally provided with a spiral screw 52, as a mixing member. Drying resistances are provided on the outer surface 53.
At the output of said drying drum 41 a unload flange 54 of the dried sand or inert, i.e. completely dehydrated, is provided.
Said drum 51 is rotated by means of motors 7, comprising an electric motor 71 and motions and return transmissions members 72 including sprocket and chain systems.
Said outlet pipe 43 outgoing from said aspirator 41, is input connected to said drying drum 51.
Said storage and offload unit 6 comprises a rotating elevator member 61, which in this embodiment is a paddle wheel, capable of getting from said drum 51 predetermined drying quantities that pass through said unload flange 54. Said rotating elevator member 61, always rotating by means of said motor means 7, transports the flow taken from said drying drum 51 into an unload hopper 62, which then transfers it into a transfer screw 63, which has a spiral shape, arranged within a cylinder 64, contained within a containment box 64'.
Said cylinder 64 has openings 65 on the surface, which in this embodiment are 4, through which appropriate flow quantities may pass, reaching, by fall, a storage hopper 66, arranged at the bottom, provided with resistors 67. Said storage hopper 66 is arranged in correspondence with said compartment 23 for transferring the already dried flow.
Downstream said storage hopper 66 a discharge valve 68 is provided positioned in correspondence with said compartment 23 for discharging, if necessary, a suitable amount of sand or inert material.
The operation of the apparatus for drying inert materials 1 as described above is as follows.
The sand or the inert material to be dried is loaded manually by said loading hopper 31, by operating said pneumatic actuators 32.
The aspirator 41 draws the flow from said loading hopper 31, through said suction pipe 42. The metering valve 44 determines the amount of flow contained within said aspirator 41 to be transferred to said drying drum 51 through said outlet pipe 43. In case of the flow aspirated in the aspirator 41 exceeds the required amount, the means for controlling the level 411 block the suction from said loading hopper 31.
The drying drum 51 rotates by passing the flow through the screw 52. The drying resistors 53 heat the flow contained within the inner volume V of said drying drum 51 to a temperature of about 350 °C, thereby eliminating any moisture component.
Due to the continuous mixing of said screw 52 of said drying drum 51, together with the heating of said drying resistors 53, the flow is continually mixed within said drying drum 51 and heated, thereby obtaining an optimum drying.
Once the sand has run through the whole screw 52, it passes through said unload flange 54 to be transferred through said rotary elevator member 61 to said transfer screw 63 by means of said unload hopper 62.
The sand, now dried, is transported by said transfer screw 63 and passed through said openings 65.
Said sand, by fall, is collected in said storage hopper 66 and kept at a temperature of 120 °C by said resistors 67, thereby preventing it to absorb again any moisture for any reason.
Whenever collecting a preset amount of sand is necessary, the operator can act on the unload product button on the pushbutton 24", so that said discharge valve 68 gets out the required amount of flow.
In addition to the above, the apparatus for drying inert materials 1 comprises load cells arranged so as to maintain the control of the amount of flow contained within said drying drum 51 and within said storage hopper 66.
In addition, the apparatus for drying inert materials 1 can be inserted into a complex plant. Particularly, the output of said discharge valve 68 may be provided with a flow pusher for transferring the dried flow and its use, everything monitored and operated by an RFID data transfer system.
Also, it should be considered that all the units of said apparatus 1 can be readily controlled by said control panel 24'.
An advantage of the drying apparatus according to the present invention is to allow a quick drying of the flow or inert in general, allowing it to be maintained and dehydrated over time.
An additional advantage of the drying apparatus according to the present invention is to allow an optimum dosage of the dried flow.

Claims

Apparatus for drying aggregates (1), such as sand, comprising
a loading unit (3), for loading aggregates to be dried,
a drying unit (5), for drying said aggregates loaded in said loading unit (3), and
a storage and offload unit (6), arranged to draw said dried aggregates from said drying unit (5) and offload the same,
wherein said drying unit (5) comprises
a drying drum (51), having an internal volume (V), in which said aggregates to be dried are collected,
mixing members (52) of said aggregates contained in said drying drum (51), and
heating means (53), for heating said internal volume (V) of said drying drum (51),
wherein said storage and offload unit (6) comprises
a storage hopper (66), in which the aggregate dried by said drying drum (51) are contained, and
an elevator member (61), such as a paddle wheel, adapted to draw from said drying drum (51) a predefined amount of said aggregates,
characterized in that the storage and offload unit (6) further comprises
heating resistors (67) for heating said aggregates contained in said storage hopper (66), a transfer screw (63), arranged above said drying drum (51), arranged to receive said aggregates from said elevator member (61), and
a cylinder (64), within which said transfer screw (63) is arranged, having one or more openings (65) on the side surface, arranged in correspondence with said storage hopper (66), such that said dried aggregates can fall by gravity into said storage hopper (66) through said one or more openings (65).
Apparatus (1) according to claim 1, characterized in that said mixing members (52) comprise a screw (52), arranged inside said drying drum (51), to transport and to mix said aggregates contained in said drying drum (51).
Apparatus (1) according to claim 2, characterized in that said screw (52) has a spiral shape.
Apparatus (1) according to any one of the preceding claims, characterized in that said drying drum (51) is rotating.
Apparatus (1) according to any one of the preceding claims, characterized in that said drying drum (51) has a cylindrical shape, which symmetry and rotation axis is arranged in a horizontal position.
Apparatus (1) according to any one of the preceding claims, characterized in that said heating means (53) comprise a plurality of drying elements (53) arranged in close proximity to the external surface of said drying drum (51).
Apparatus (1) according to claim 1 , characterized in that said storage and offload unit (6) comprises a discharge valve (68), for expelling a predetermined quantity of said aggregates from said hopper storage (66).
Apparatus (1) according to any one of the preceding claims, characterized in that said loading unit (3) comprises a loading hopper (31) for loading the aggregates to be dried.
Apparatus (1) according to any one of the preceding claims, characterized in that it comprises a suction unit (4), for transferring said aggregates from said loading unit (3) to said drying unit (5).
Apparatus (1) according to claim 9, characterized in that said suction unit (4) comprises
an aspirator (41),
a suction pipe (42) connected between said loading unit (3) and said aspirator (41), and
an outlet pipe (43), connected between said aspirator (41) and said drying drum (51).
Apparatus (1) according to claim 10, characterized
in that said aspirator (41) comprises means (411) for the control of the level of the aggregates contained in said aspirator (41) and
in that said suction means (4) comprise a metering valve (44), arranged along said outlet pipe (43), for determining the amount of aggregates to be transferred to said drying unit (5).
Apparatus (1) according to any one of the preceding claims, characterized in that it comprises a container (2) having a front opening (21) with a respective door (22) for the access to said loading unit (3), and a compartment (23), arranged in correspondence with said storage and offload unit (6).