WO2013168115A1

WO2013168115A1 - Appliance for measuring the humidity of a material

Info

Publication number: WO2013168115A1
Application number: PCT/IB2013/053746
Authority: WO
Inventors: Paolo SERPAGLI
Original assignee: Pertec Sistemi S.R.L.
Priority date: 2012-05-11
Filing date: 2013-05-09
Publication date: 2013-11-14
Also published as: EP2847578A1; ITMO20120127A1

Abstract

The appliance (1) for the measurement of the humidity contents of a material comprises a resonant sensor (3) with electromagnetic waves which can be positioned in the proximity of a material (B) to be measured, wherein the material is moved along a forward direction (C) at a predefined forward speed and the resonant sensor (3) is suitable for measuring the humidity contents of the material (B) during the movement along the forward direction (C), a film (5) in a material permeable to electromagnetic waves, wherein at least one section of said film (5) has a first face arranged in contact with a measurement surface (4) of the resonant sensor (3) and a second face which can be positioned in contact with the material (B), and movement means (6) of the section of the film (5) along the forward direction (C) at a speed substantially equal to the forward speed of the material (B).

Description

APPLIANCE FOR MEASURING THE HUMIDITY OF A MATERIAL

Technical Field

The present invention relates to an appliance for the measurement of the humidity contents of a material.

Background Art

The use in different sectors of more or less sophisticated appliances for the measurement of humidity of loose material is known, e.g. of the type of powders or granules of different type used in the ceramic, food industry or in the wood processing sector, or other types of materials, such as leather, paper or the like.

In particular, these appliances generally involve the positioning of one or more humidity sensors along a movement line of the material to be measured made up, e.g., of a conveyor belt or a similar device.

For example, a first type of such known appliances involves the measurement of humidity without contact and uses special electromagnetic wave sensors, in particular microwaves, suitably positioned along the movement line of the material to be measured.

In particular, these appliances involve the use of a transmitter and a receiver of a microwave signal arranged above and below, respectively, a section of the conveyor belt suitable for moving the material to be measured.

The transmitter sends a microwave signal with a predefined frequency through the material and a part of the microwave signal is absorbed by the material itself before reaching the receiver.

Therefore, analysing the difference between the microwave signals sent and received and according to the technical characteristics of the material and the thickness of the layer of material on the conveyor belt it is possible to determine the humidity of the material itself.

These appliances, however, are not without drawbacks as they are highly complex and require considerable initial investments and maintenance costs. These known appliances are also unable to guarantee constantly correct humidity measurements when used in working environments that are not perfectly clean and in the presence of dust dispersed in the atmosphere which, sticking to the sensitive surface of the sensors, invalidate the measurements taken.

A second type of known appliances involve the use of one or more so-called microwave resonant sensors suitable for determining the specific dielectric constant of the material and, consequently, all its physical characteristics, including, e.g., the humidity contents.

In particular, the resonant sensors used have a surface that emits a microwave signal which is suitable for being positioned directly in contact with the material to be measured.

Appropriate variations of parameters such as the resonance frequency or the factor of merit are used, to measure the value of the dielectric constant of a material sample.

However these known appliances also have a number of drawbacks.

In fact, these appliances require continuous operations to clean the sensitive surface of the resonant sensor since, this surface being in direct contact with the material to be measured, one part of the measured material ends up being deposited on it, thus considerably affecting the quality of the measurements taken.

This problem occurs particularly in the case of measuring the humidity of loose materials such as powders or granules.

Moreover, when measuring coherent materials, such leather or the like, the continuous rubbing of the sensitive surface of the resonant sensor on the surface of the material may partly damage the material itself.

Description of the Invention

The main aim of the present invention is to provide an appliance for the measurement of the humidity of a material which ensures the precise and continuous monitoring of the humidity of a material.

Another object of the present invention is to provide an appliance for the measurement of the humidity contents of a material which allows to minimise the number of manual maintenance jobs by the operating staff.

Another object of the present invention is to provide an appliance for the measurement of the humidity contents of a material which allows to minimise the risk of damage occurring to the measured material.

Another object of the present invention is to provide an appliance for the measurement of the humidity contents of a material which allows to overcome the mentioned drawbacks of the state of the art in the ambit of a simple, rational, easy and effective to use as well as low cost solution.

The above objects are obtained by the proposed appliance for the measurement of the humidity contents of a material, comprising at least a resonant sensor with electromagnetic waves which can be positioned in the proximity of a material to be measured, wherein said material is moved along a forward direction at a predefined forward speed and said resonant sensor is suitable for measuring the humidity contents of said material during the movement along said forward direction, characterized by the fact that it comprises at least a film in a material permeable to electromagnetic waves, wherein at least one section of said film has a first face arranged in contact with a measurement surface of said resonant sensor and at least a second face which can be positioned in contact with said material, and movement means of said section of the film along said forward direction at a speed substantially equal to said forward speed of the material.

Brief Description of the Drawings

Other characteristics and advantages of the present invention will become more evident from the description of a preferred, but not sole, embodiment of an appliance for the measurement of the humidity contents of a material, illustrated purely as an example but not limited to the annexed drawings in which:

Figure 1 is a side schematic view of the appliance according to the invention. Embodiments of the Invention

With particular reference to such figures, globally indicated by 1 is an appliance for the measurement of the humidity contents of a material, usable particularly for the precise measurement of the humidity of loose and coherent materials. The appliance 1 can be used, e.g., to measure the humidity of powders or granules of different type used e.g. in the ceramic and food industry or in the wood processing sector, or with other types of material such as leather, paper or the like.

The use of the appliance 1 for the measurement of the humidity contents of materials of different type cannot however be ruled out.

The appliance 1 comprises a bearing structure 2 installable on a conventional forward feed line A of a material B to be measured in an industrial system.

As illustrated purely as an example in the diagram of figure 1, the forward feed line A of the material B can be made of a conventional conveyor belt.

During normal operation, the material B on the conveyor belt A is moved along a forward direction C at a predefined forward speed.

The appliance 1 comprises a resonant sensor 3 with electromagnetic waves supported by the bearing structure 2, positionable in the proximity of the material B and suitable for measuring the humidity contents of the material B as the material moves forward.

Preferably, the resonant sensor 3 has a substantially flat measurement surface 4 suitable for emitting and receiving electromagnetic waves.

Preferably, the resonant sensor 3 is made up of a microwave resonant sensor of the type conventionally used for the contact measurement of the specific dielectric constant of the material and, consequently, of all the physical characteristics of the material, including, e.g., the humidity contents.

Advantageously, the appliance 1 comprises a film 5 made from a material that is permeable to electromagnetic waves, in particular microwaves, with at least one section with a first internal face positioned in direct contact with the measurement surface 4 of the resonant sensor 3 and a second external face positioned in direct contact with the material B moved by the conveyor belt A. Preferably, the film 5 comprises polytetrafluoroethylene (PTFE) which is permeable to microwaves.

Advantageously, the appliance 1 comprises movement means, indicated overall in the figure by reference 6, suitable for moving the aforementioned section of the film 5 along the forward direction C of the material B at a substantially equal speed to that of the forward speed of the material itself.

The presence of the film 5 allows to prevent the measurement surface 4 of the resonant sensor 3 from coming in direct contact with the material B to be measured.

This prevents the deposit of the material B on the measurement surface 4, thus considerably limiting the number of maintenance jobs required to clean the resonant sensor 3.

Moreover, the movement of the film 5 along the forward direction C, done at the same forward speed as the material B, also prevents friction between the film and the material, thus considerably limiting the possibility of damaging the material or the film itself.

In particular, the movement means 6 comprise motor means, not illustrated in the figure, operationally connected to the film 5 and adjustment means, also not shown in the figure, operationally connected to the motor means and suitable for adjusting the movement speed of the film 5 depending on the forward speed of the material B.

Usefully, the aforementioned adjustment means can be of the automatic and/or manual type.

Referring to the particular embodiment of the appliance 1 illustrated schematically in figure 1, the movement means 6 comprise a system of rollers 7, 8 and 9 on which the film 5 is closed in a loop.

In particular, the movement means 6 comprise a first roller 7 and a second roller 8 arranged spaced from each other on opposite sides with respect to the resonant sensor 3 and a third roller 9 spaced from the first and second rollers 7 and 8, above the resonant sensor 3.

The film 5 is closed in a loop around the first, second and third rollers 7, 8 and 9 and has a substantially horizontal section laid between the first roller 7 and the second roller 8 which has the first face arranged in contact with the measurement surface 4 of the resonant sensor and the second face positionable in contact with the material B.

Preferably, the motor means are operatively associated with the third roller 9. The realization of movement means 6 by means of different technical solutions cannot however be ruled out.

Usefully, the appliance 1 comprises cleaning means 10 suitable for keeping the film 5 clean during use. In particular, referring to a preferred but not exclusive embodiment of the appliance 1, the cleaning means 10 are composed of a cleaning element, of the type of a brush and/or a sponge, arranged in contact with a portion of the face of the film 5 intended to be placed in contact with the material B.

Preferably, the cleaning element 10 is arranged along the section of film 5 running between the second roller 8 and the third roller 9, in the proximity of the second roller 8.

Usefully, the bearing structure 2 comprises a container 11 for housing and protecting the resonant sensor 3 and part of the film 5.

In practice, the measurement surface 4 of the resonant sensor 3 and the horizontal section of film 5 suitable for being placed in contact with the material B are arranged in correspondence to a lower opening of the container 11 facing towards the conveyor belt A.

Usefully, the appliance 1 can comprise air suctioning means, not illustrated in the figure, associated with the container 11 and suitable for suctioning and purifying the air from any dust present inside the container itself.

In particular, the container 11 preferably comprises a top mouth 12 which can be connected to the suction means.

Usefully, the appliance 1 can comprise height variation means, schematised in the figure and indicated by reference 13, used to vary the height of the whole container 11, and therefore of the resonant sensor 3 and the film 5, according to the thickness of the material B or the layer of material B arranged on the conveyor belt A.

In particular, these height variation means 13 can be made up of appropriate support carriages of the container 11 sliding along the respective uprights of the bearing structure 2.

If the material B to be measured is a loose material, the appliance 1 can also have an appropriately shaped plate 14, positionable upstream from the resonant sensor 3, above the conveyor belt A and substantially inclined with respect to the forward direction C of the material B.

Usefully, the plate 14 is suitable for flattening the material B before the measurement by means of the resonant sensor 3. Suitable height and/or inclination adjustment means, schematised in the figure and indicated by reference 15, are suitable for varying the height and/or the inclination of the plate 14 according to the thickness of the layer of material B to be moved towards the resonant sensor 3.

In particular, these height and/or inclination variation means 15 can be made up of a suitable carriage sliding along a respective upright of the bearing structure 2.

It has in practice been ascertained how the described invention achieves the proposed objects.

In particular, the presence of the film permeable to microwaves avoids the direct contact between the measuring surface of the resonant sensor and the material, thus guaranteeing a reliable measurement of the humidity over time and at the same time drastically reducing the number of maintenance jobs required on the sensor.

Moreover, the movement of the film along the forward direction of the material, at the same speed as the material, prevents any rubbing of the material itself which could damage it.

Claims

1) Appliance (1) for the measurement of the humidity contents of a material, comprising at least a resonant sensor (3) with electromagnetic waves which can be positioned in the proximity of a material (B) to be measured, wherein said material is moved along a forward direction (C) at a predefined forward speed and said resonant sensor (3) is suitable for measuring the humidity contents of said material (B) during the movement along said forward direction (C), characterized by the fact that it comprises at least a film (5) in a material permeable to electromagnetic waves, wherein at least one section of said film (5) has a first face arranged in contact with a measurement surface (4) of said resonant sensor (3) and at least a second face which can be positioned in contact with said material (B), and movement means (6) of said section of the film (5) along said forward direction (C) at a speed substantially equal to said forward speed of the material (B).

2) Appliance (1) according to the claim 1, characterized by the fact that said movement means (6) of the film (5) comprise motor means and adjustment means operatively connected to said motor means and suitable for adjusting the movement speed of said film (5) depending on said forward speed of the material (B).

3) Appliance (1) according to the claim 2, characterized by the fact that said adjustment means are of the automatic and/or manual type.

4) Appliance (1) according to one or more of the preceding claims, characterized by the fact that said movement means (6) comprise at least a roller system (7, 8, 9) and by the fact that said film (5) is closed in a loop on said roller system (7, 8, 9).

5) Appliance (1) according to one or more of the preceding claims, characterized by the fact that said roller system (7, 8, 9) comprises at least a first roller (7) and a second roller (8) arranged spaced from each other on substantially opposite sides with respect to said resonant sensor (3) and by the fact that said section of the film (5) is laid between said first roller (7) and said second roller (8) with said first face arranged in contact with said measurement surface (4) of the resonant sensor (3) and said second face positionable in contact with said material (B).

6) Appliance (1) according to the claim 5, characterized by the fact that said roller system (7, 8, 9) comprises at least a third roller (9) substantially spaced from said first roller (7) and said second roller (8) and by the fact that said film (5) is closed in a loop around said first, second and third rollers (7, 8, 9).

7) Appliance (1) according to one or more of the claims from 2 to 6, characterized by the fact that said motor means are operatively connected to at least one between said first roller (7), said second roller (8) or said third roller (9).

8) Appliance (1) according to one or more of the preceding claims, characterized by the fact that it comprises cleaning means (10) for cleaning said film (5).

9) Appliance (1) according to one or more of the preceding claims, characterized by the fact that said cleaning means (10) comprise at least a cleaning element (10) arranged in contact with at least a portion of said second

10) Appliance (1) according to one or more of the preceding claims, characterized by the fact that it comprises height variation means (13) of said resonant sensor (3) and of said film (5).

11) Appliance (1) according to one or more of the preceding claims, characterized by the fact that it comprises at least a container (11) for housing and protecting at least a portion of said film (5) and of said resonant sensor (3).

12) Appliance (1) according to one or more of the preceding claims, characterized by the fact that it comprises air suctioning means associated with said container (1 1) and suitable for suctioning and purifying the air inside said container (1 1).

13) Appliance (1) according to one or more of the preceding claims, characterized by the fact that said resonant sensor (3) is of the type of a microwave sensor.

14) Appliance (1) according to one or more of the preceding claims, characterized by the fact that said film (5) comprises polytetrafluoroethylene (PTFE).