WO2010125454A1

WO2010125454A1 - Microwave resonator for measurements on a flowable material

Info

Publication number: WO2010125454A1
Application number: PCT/IB2010/000989
Authority: WO
Inventors: Luca Mucchi
Original assignee: Ats Microtech S.R.L.
Priority date: 2009-04-30
Filing date: 2010-04-30
Publication date: 2010-11-04
Also published as: ITMO20090109A1

Abstract

A device connectable to an environment wherein a flowable material is processed, comprises a measuring chamber (5; 205) adapted to be put in communication with said environment for receiving the flowable material, a microwave sensor (4; 204) for measuring a property of the flowable material received in the measuring chamber (5; 205); handling means (61) for introducing the flowable material in the measuring chamber (5; 205) and from the measuring chamber (5; 205) in said environment after, the microwave sensor (4; 204) has measured said property.

Description

MICROWAVE RESONATOR FOR MEASUREMENTS ON A FLOWABLE MATERIAL

The invention regards a device for measuring a property, for example the humidity, of a flowable material, particularly a powdered, or grained material. The device according to the invention can be used in drying, granulation, agglomeration, instantation, coating, lamination, or spheronization, plants, particularly of the fluid bed type. The flowable material processed by the device according to the invention can be a food, pharmaceutical product or of other type.

In other words, the flowable material can be, for example, a powdered or grained material, crushed materials or beans or, in any event, homogeneous or inhomogeneous materials capable of flowing in the measuring chamber, such as coffee, wood chips, tobacco, etc; it is obvious that also liquids, foams, creams, dispersions, mixtures, or mixes or any other substance capable of passing in the measuring chamber fall in the materials which can be analyzed by the present device.

It is known a fluid bed apparatus comprising a hopper delimited by a sloped wall, a measuring device is connected to the wall, said measuring device comprising a microwave sensor. The measuring device is located so that it is flush with the sloped wall and continuously measures the humidity of a product flowing inside the hopper along the sloped wall.

A disadvantage of the above mentioned measuring device is that such a device delivers humidity measures which can be inaccurate, because the density of the product flowing along the hopper sloped wall can vary every moment. In other words, little compacted product amounts, that is having a relatively low density, followed by a more compacted product amount, that is having a greater density, can flow along the sloped hopper wall. The density variations adversely affect the precision of the humidity measure.

It is also known from document DE4004119, a device for determining the humidity content of a test material, wherein a portion of the material to be analyzed is drawn and directed to a measuring channel length to which is coupled a microwave sensor. A pneumatically driven valve opens/closes an input to the measuring area and a further valve, also pneumatically driven, opens/closes the material drain in the measuring area. Document WO9007110 shows a humidity measuring device located in line with a food material processing apparatus, wherein a measuring chamber opens in the material flow direction for receiving a predetermined quantity of the same and conveying it to a measuring area where a microwave device detects a physical parameter (humidity) of the product. A draining hopper is located in front of the material input with respect to the measuring area for ejecting the material toward the main flow.

An object of the invention consists of improving the devices for measuring a property of a flowable material. Another object consists of providing a device for measuring a property of a flowable material having a good precision. Another object consists of providing a measuring device which allows to accurately control the measuring conditions and to increase the reliability of the sensor reading.

Than, an object consists of allowing a quick setting of the conditions adapted to the measure and therefore of speeding up the capacity of the device reading.

One or more of the above mentioned objects are attained by a device and method of measuring which exploits the technical characteristics according to the independent claims, possibly combined with one or more of the dependent claims.

In a first aspect of the invention, it is provided a device connectable to an environment wherein a flowable material is processed, comprising a measuring chamber adapted to be put in communication with said environment for receiving the flowable material, a microwave sensor for measuring a property of the flowable material contained in the measuring chamber, handling means for at least reintroducing the flowable material in the measuring chamber in said environment.

The device according the first aspect of the invention enables to obtain accurate measures of the property of the flowable material.

In fact, in a first condition, the measures are performed when the flowable material fills the measuring chamber, in other words in static conditions. The density of the flowable material contained in the measuring chamber does not substantially change during the measure. Moreover, the flowable material is compacted while it fills the measuring chamber, so that it will be also possible to foresee that density variations are not excessively high between two consecutive batches of the flowable material. In this way, the inaccuracies are avoided occurring in the known device, in which the flowable material density substantially varies as the flowable material slides along the sloped wall of the hopper on which the microwave sensor is located.

Moreover, in a second condition, the measures are performed when the flowable material has filled the measuring chamber, but the conveying means and the discharging means are both active, in other words in dynamic conditions. This promotes an improvement of the homogeneity of the sample to be measured.

Possibly, the homogenizing can be promoted by a step of vibrations applied to the chamber (and therefore to the material contained in it) , for example before the measure.

In a version, the device comprises conveying means for conveying the flowable material from said environment to the measuring chamber. The conveying means can comprise an input auger conveyor.

The conveying means enable to fill the measuring chamber in a controlled way, which moreover increases the device precision.

In a version, the device comprises enabling means for enabling the measure of the property by the microwave sensor when the flowable material has reached a predetermined amount in the measuring chamber. The enabling means can comprise a level sensor, for example of an inductive, capacitive, ultrasonic or optic type or also a gravimetric sensor.

Thanks to the enabling means, the microwave sensor performs the measure only when the measuring chamber has been filled by the desired amount. This fact enables to avoid that the measure is done when the measuring chamber is still partially empty, which could distort the obtained result and enables to work in controlled conditions .

The conveying means can be controlled by a control unit which receives a signal by the enabling means, the control unit being programmed for stopping the conveying means when the flowable material has reached the predetermined amount in the measuring chamber. In this way, the conveying means are prevented from continuously delivering flowable material in the already filled measuring chamber, which could form excessively high pressures in the measuring chamber and consequently cause fails in the conveying means.

In a version, the discharging means handle the flowable material from the measuring chamber to said environment. In a version, the conveying means and discharging means are coincident.

The handling means enable to empty the measuring chamber in a controlled way and convey the flowable material to said environment along any desired path. The discharging means can comprise an auger output conveyor.

The output auger conveyor and the input auger conveyor can extend along substantially parallel axes, particularly horizontal. In a version, the discharging means can comprise pneumatic handling means. Alternatively, the discharging means can comprise a sliding element inside the measuring chamber, adapted to thrust the flowable material outside the measuring chamber.

In a version, the measuring chamber can be a through chamber having only a first opening through which the flowable material enters and a second opening through which the flowable material exits.

Alternatively, the measuring chamber can be a blind chamber having one opening adapted to be put in communication with said environment, so that the flowable material enters in, and exits from, the measuring chamber through the same opening. In this case, it is obtained a device which is particularly compact and small-sized. In a version, the microwave sensor defines at least partially the measuring chamber and it can contact the flowable material during the measure.

The microwave sensor can be cylindrical. In this case, the measuring chamber is defined inside the microwave sensor. The microwave sensor can also be planar, or also multi- faced planar in order to define an envelope surface. The device can comprise cleaning means for removing possible residues of the flowable material from the measuring chamber when the measuring chamber is emptied. The cleaning means can comprise delivering means for delivering a cleaning fluid, particularly a gas, such as compressed air, a liquid and/or a mixture of liquid and gas, inside the measuring chamber.

Alternatively, the cleaning means can comprise a scraping element slidingly contacting an inner surface of the measuring chamber.

The cleaning means enable to prevent the formation of build-ups and encrustations of flowable material in the measuring chamber, which could adversely affect the precision of the measure and contaminate the material having the properties to be measured.

In a second aspect of the invention, it is provided a sensor comprising a cylindrical microwave resonator, an input port for enabling an electromagnetic field to enter the microwave resonator, an output port for enabling the electromagnetic field to output the microwave resonator, a turn device being associated to the input port and an antenna device being associated to the output port. The turn device enables to make a current coupling between the input electromagnetic field and the microwave resonator, while the antenna device enables to make a voltage coupling between the output electromagnetic field and the microwave resonator. This fact enables to obtain a sensor having a high sensitivity.

The sensor can comprise annular dielectric means defining at least partially a measuring chamber.

The annular dielectric means can be housed at least partially in an enclosure.

Particularly, the enclosure can comprise a first wall and a second wall, the annular dielectric means are located between these walls.

The first and the second walls are connected to each other by a connecting portion.

In an embodiment, the antenna device comprises a launcher element having an end embedded in the annular dielectric means. The launcher element can pass through the first enclosure wall.

In another embodiment, the turn device comprises a further launcher element having a first end portion passing through the first enclosure wall and a second end portion received in the second enclosure wall. The further launcher element passes through the annular dielectric means.

The further launcher element can be substantially parallel to the connecting portion.

The launcher element and the further launcher element are substantially parallel to each other.

A contact element, for example a threaded element, can be housed in the second enclosure wall for contacting the further launcher element. The contact element can be located in contact with a transversal end surface of the further launcher element.

The contact element can extend along the same axis along which the further launcher element extends.

The contact element avoids to apply flexural stresses to the further launcher element, which can undesiderably deform the further launcher element. Moreover, the contact element enables to make an effective and strong contact with the further launcher element.

An aspect of the invention refers to a method of measuring a parameter of a material by a device connectable to an environment in which a flowable material is processed, comprising a measuring chamber adapted to be put in communication with said environment for receiving the flowable material, a microwave sensor for measuring a property of the flowable material contained in the measuring chamber, discharging means (51) for reintroducing the flowable material in the measuring chamber in said environment, the method comprising the steps of: delivering an amount of the material to be analyzed to the measuring chamber; measuring a parameter of said material by the microwave sensor; ejecting said material from the measuring chamber. According to a further aspect, the method comprises a sub-step of conveying said material from a source to the measuring chamber by conveying means, said conveyance being made by a positive transfer of the material from the source to the measuring chamber.

According to a further aspect, the method steps of supplying, measuring, ejecting can be temporally consecutive.

According to a further aspect, the method steps of supplying, measuring, ejecting can be partially overlapping, in particular the measuring step being performed during at least the last part of the supplying step and the first part of the ejecting step. According to a further aspect, the method can provide a further step of measuring by the microwave sensor when the chamber has been emptied of the material, particularly for determining a contamination degree of the measuring chamber and/or of the sensor. According to a further aspect, the method can provide the step of supplying an amount of the material to be analyzed to the measuring chamber and of ejecting said material from the measuring chamber through the same opening connecting the measuring chamber to the environment, particularly said opening being the only opening connecting the measuring chamber to the environment . The invention will be better understood and embodied with reference to the attached drawings, which show some illustrative and non limitative embodiments, wherein: Figure 1 is a perspective view of a device for measuring a property of a flowable material;

Figure 2 is a perspective view of the device of Figure 1, taken from a different angler- Figure 3 is a section view of the device of Figure 1; Figure 3a is an alternative embodiment of the device of Figure 1; Figure 4 is a perspective view of a device for measuring a property of a flowable material, according to an alternative embodiment;

Figure 5 is a sectional view of a device for measuring a property of a flowable material, according to another alternative embodiment, Figure 6 is a perspective view of a microwave sensor which can be employed in the devices of Figures 1 - 5. Figure 1 shows a device 1 for measuring a property of a flowable material, particularly a powdered or grained material, crushed materials or beans material or in any case homogeneous or inhomogeneous materials capable of flowing in the measuring chamber, such as coffee, wood chips, tobacco, et<; it is to be understood that also liquids, foams, dispersions, mixtures or mixes, or in any case any substances capable of passing in the measuring chamber fall in the materials which can be analyzed by the present device. The device 1 is connectable by coupling means 59, such as a connecting element, to an environment in which a powdered material is processed, particularly to a closed environment. The environment to which the device 1 is connected can be an environment located inside a fluid bed apparatus, or an environment located inside at atomizer, or also an environment closed by a transporting duct for transporting the powdered material. In the example shown in Figure 1, the connecting element comprises a flange 2 adapted to be connected to a wall which defines the environment in which the powdered material is processed, by a plurality of connecting holes 3. In the example of Figure 5, the coupling means 59 comprise a flange 202. The device 1 comprises a microwave sensor 4, which enables to measure a property of the powdered material, for example the humidity, the permittivity, the density. The microwave sensor 4 can also supply information about the granulometry of the powdered material.

The microwave sensor 4 is located so that it interacts with the flowable material received in a measuring chamber 5, shown in Figure 3. In the non-limitative shown example, the microwave sensor 4 is cylindrical and a portion of the measuring chamber 5 extends inside it. In an alternative embodiment, the microwave sensor can be of the planar type and faces a wall of the measuring chamber 5.

In a further possible embodiment, the sensor 4 will be provided with one planar face or with a plurality of planar faces adapted to cooperatively define a cylindrical envelope or in any case other more or less closed geometrical shapes around the measuring chamber (annular, elliptical, U-shaped, double C, etc.). It is to be noted that in the embodiment shown in Figures 5 and 6, the sensor 4, 204 cooperates to define part of the inner surface of the measuring chamber 5, 205 which is in direct contact with a material having the physical or chemical property to be known. However, in not shown examples, the sensor can be externally located with respect to the measuring chamber wall without falling out the scope of the present invention.

In any case, as described above, the microwave sensor 4 can define at least partially the measuring chamber 5 and it can come directly in contact with the flowable material during the measure.

The device 1 comprises an input duct 6 through which the powdered material coming from the environment connected to the device 1 can be conveyed to the measuring chamber 5. Conveying means 57 are housed (at least partially) inside the input duct 6. Such conveying means 57 are arranged for positively drawing and transferring the material from a source (for example the main flow of the same inside the processing apparatus) to the measuring chamber 5. Particularly, the conveying means 57 enable to control the input material flow because they can determine the predetermined inflow value and possibly changeable as a function of the needs. In other words, it is possible to arrange the conveying means 57 between a plurality of different input/entry material flows, which can be independent and not related to the speed and/or pressure of the material coming from the source and entering the duct 6 before intercepting the conveying means 57. The conveying means 57 can be formed, for example, by an inlet auger 7, which can extend along a substantially horizontal axis.

According to the embodiment of Figure 3, the conveying means 57, such as the input auger 7, can have an end terminating near the measuring chamber 5, in a position above the microwave sensor 4 (or in any case upstream of the sensor 4 with respect to the material flow direction 52 in the device) . A further end of the conveying means 57, for example, of the input auger 7, projects from a part opposed to said material source; this further end is on a part of the flange 2 opposed to the microwave sensor 4, in order to extend, during the use, inside the environment wherein the powdered material is processed, for drawing the powdered material from said environment. The input auger 7, but more generally the conveying means 57, is/are rotatively driven by a motor 8, for example of the pneumatic or electric type, which can transmit the motion to the same means/input auger 7 by a transmission device not shown, comprising for example a belt or a gear group, located inside a housing 9. On the contrary, in the embodiment of Figure 3a, the conveying means 57 are located in the measuring chamber 5 bottom.

The device 1 comprises discharging means 51 for removing the powdered material from the measuring chamber 5 after the microwave sensor 4 has measured the desired property (or also during the measuring step as it will be better clarified in the following) . The discharging means 51 enable to introduce again the powdered material in the environment connected to the device 1. The discharging means 51 can comprise an output 50 or an output duct 10 connecting the measuring chamber 5 to the environment where the powdered material is processed. Inside the output duct 10, there are or not discharging means 51 adapted to promote the outflow of the powdered material which, as a simple example, can comprise an output auger 11. The discharging means 51 will be also configured for positively drawing and transferring the material from the measuring chamber 5 to the environment. Particularly, the discharging means 51 enable to control the output material flow in that they can estimate a predetermined outflow value and possibly changeable as a function of the needs.

In other words, it is possible to arrange the discharging means 51 between a plurality of different input/output material flows which can be independent and unrelated from the speed and/or pressure of the material coming from the measuring chamber 5 and independent from the speed and pressure conditions downstream of the same in the environment where there is the main material flow.

The discharging means 51 can comprise, for example, an output auger 11, and can extend along an axis parallel to the input auger 7 axis of, particularly horizontal. In the embodiment of Figure 3, the discharging means 51 will be located downstream of the sensor 4 along the material flow direction 52 in the device and particularly the output auger 11 can be operatively located beneath the input auger 7, at a level lower than that of the microwave sensor 4 always along said material flow direction 52. The discharging means 51, that is the output auger 11, are/is driven by a further motor 12, for example of the pneumatic or electrical type, by a transmission device, comprising, for example, a belt or a gear set, contained in a further housing 13. From the geometrical point of view, the device of Figure 3 is configured in order to have, along the flow direction 52 of the material to be measured, the input duct 6 having an envelope mainly along a first axis 53, the measuring chamber 5 having an envelope mainly along a second axis 54 (optionally) transversal to the first 53 and the output duct 10 having an envelope mainly along a third axis 55 (optionally) transversal to the second one 54.

In the embodiment shown in Figure 3a, the handling means 61 (comprising the conveying means 57 and the discharging means 51) are completely defined by a single auger 7, 11.

Speaking broadly, the input channel 6 and the output channel 10 are coincident and therefore the opening 50 forms the only access to the chamber. The conveying means 57 (that is the auger 7 in the example embodiment shown) positively and in a controlled way draw the material from the environment and transfer it along the flow direction 51 into the device. Once the chamber 5 is full, the sensor performs the measure. This measure can be done statically (the material is still) or also dynamically (the material moves slightly, up or down in the chamber 5 depending on whether the handling means 61 are active as conveying means with the material entering or as discharging means 51 with the material exiting) . As said before, the handling means can be configured in an operative discharging condition and act as discharging means taking then the material to the outer environment always along a material flow direction 52 which will therefore assume an opposed direction inside the duct 10, 6.

In other words, the conveying means and the discharging means are again coincident because they are for example defined by the same auger 7, 11. Obviously, all the other elements of the device remain unchanged and are identified by the same reference numbers of Figures 1-3.

The device 1 (according to all the embodiments) moreover comprises a sensor adapted to supply a measure agreement signal, such as a level sensor 14, shown in Figure 1, which can be of the inductive, capacitative, optical type or of other kind and enables to detect when the powdered material has reached a predetermined level inside the measuring chamber 5. In any case, it can be used a different sensor adapted to the purpose, for example a weight sensor; alternatively, by suitably controlling the input and output flows, that is the flow rates, by the conveying 57 and discharging means 51 it is possible to determine at least one measure condition wherein it is possible to perform reliable measures by the sensor 4 and a transient condition (for example when the measuring chamber 5 is full or empty) wherein despite it is possible to take a measure, the same is not considered reliable

it is possible to perform a possible measure, cannot be considered reliable.

Particularly, the agreement sensor, such as the level sensor 14, can be located in a region of the measuring chamber 5 adjacent to an input area 56 of the powdered material.

The agreement/level sensor 14 outputs a signal which is transmitted to a control unit present in the device 1 or cooperating with the device 1. The control unit is programmed and configured in order to perform the measure in at least two main operative conditions and to possibly perform the measure in a further control operative condition.

In a first operative condition, the control unit is configured for stopping the conveying means 57 (for example the input auger 7) when the powdered material has reached the predetermined level or amount in the measuring chamber 5 and enabling, simultaneously or later, the measure by the microwave sensor 4. Obviously the control unit could be configured for performing the measure only when a determined time has elapsed from the start of the conveying means 57, that is the measure is triggered by a timer.

In a second alternative operative arrangement, the measure can be performed when the conveying means 57 are operating (possibly, but not necessarily, at a reduced speed with respect to the inlet material speed) and also when the active discharging means 51 are operating

(obviously this arrangement can be done with reference to the embodiment of Figure 3) .

Obviously, it is possible to perform dynamic measures also with the device of Figure 3a as said before.

In this way, in the measuring chamber 5 it is possible to generate a material flow, particularly with a stationary motion, which enables to homogenize the distribution of the material and possibly to improve the measure performance.

In fact, the powdered or grained materials (or, anyway, many of the previously described materials) tend to form areas having different densities and consequently inhomogeneous distributions which can adversely affect the accurate measures of physical properties such as the humidity. A (slight) advancing motion along the direction 52 improves the homogenizing of the material to be analyzed increasing the performance of the device.

In this case, the agreement sensor, such as the level sensor 14 or a timer, can determine the instant in which the sensor 4 for the measure will be started. Moreover, it is to be noted that it can be provided a step of vibrating the measuring chamber containing the material to be analyzed, for example before performing the measure, always for improving the homogenizing of the material and increasing the measure precision. On the contrary, in the control operative arrangement, the measuring chamber is emptied and the sensor 4 performs a measure. In this way, it is possible to determine a contamination degree of the sensor. As a function of the result of the measure, it will be possible to perform a further cleaning step or triggering also an alarm signal (for example a flashing LED or the like) which calls the attention and/or asks the presence of an operator.

To this end, in order to determine the empty measuring chamber condition, a further level sensor downstream of the sensor 4 along the material flow direction 52 can be used or a gravimetric sensor, that is a timer, can be used.

Moreover, the device 1 can comprise auxiliary sensors, for example a temperature sensor 15 shown in Figure 1 which enables to measure the powdered material temperature. The temperature sensor 15 can be located in a region below the measuring chamber 5, adjacent to the output duct 10, but generally it can be located in any areas of the device wherein it is adapted to give a reliable measure.

For keeping clean the measuring chamber 5, particularly when the powdered material becomes to stick to the walls of such chamber, there are provided cleaning means comprising, for example, a dispenser 16 for dispensing a liquid and/or a pressurized gas jet, particularly water and/or compressed air, inside the measuring chamber 5. To this end, it is to be noted that the control unit can receive the material temperature from the temperature sensor and consequently adjust the temperature of the cleaning air/liquid, for example in order to avoid problems during the measuring step, such as condensate in the chamber or the like. The dispenser 16 can be attached to a cover 17 located above the measuring chamber 5, in order to dispense a pressurized gas and/or a liquid jet directed from the top to the bottom. As it is shown in Figure 3, in one of the walls of the measuring chamber 5, and particularly in the cover 17, at least one, and particularly a plurality of passages 18 is made for splitting the pressurized gas or liquid jet or a mixture thereof dispensed by the dispenser 16 in a plurality of flows which enable to maintain clean all the inside surface of measuring chamber 5. The cover 17 can be made of a transparent material, for enabling an operator to check possible anomalies in the measuring chamber 5. For the same reason, a bottom wall 19 of the measuring chamber 5 can be made of a transparent material. In an alternative version, the cleaning means can comprise cleaning mechanical means, for example a brush or a scraping element, or a combination of mechanical and cleaning pneumatic/liquid means. The microwave sensor 4 comprises a microwave resonator and can be of the type described in the international patent application PCT/IB2007/001194, whose contents are incorporated in the present specification. Alternatively, it is possible to use a microwave sensor 4 of the type shown in Figure 6. Figure 6 shows a microwave sensor 4 of the cylindrical type, comprising an enclosure 32, possibly made in two parts, which can have a "C-shaped" cross section. Particularly, the enclosure 32 comprises a first 42 and second walls 43, substantially parallel to each other and horizontally arranged during the use. The first 42 and second walls 43 are connected to each other by a connecting portion 44, which extends vertically during the use. The enclosure 32 can be made of an electrically conductive material, for example a metal.

Dielectric means are housed in the enclosure 32. In the shown example, the dielectric means comprise an inner ring 33, which can be made of alumina (Al₂O₃) , having an inner surface 34. The dielectric means can moreover comprise an outer ring 35, made for example of polytetrafluoroethylene (PTFE), surrounding the inner ring 33.

The enclosure 32 is located between a first 36 and second tubular elements 37 which, during the use, are respectively located above and below the enclosure 32. The inner surface 34 is flush with respective inner surfaces of the first 36 and second tubular elements 37, in order to define the measuring chamber 5. The first 36 and second tubular elements 37 each comprise a fixing flange 38 adapted to abut against the enclosure 32 for respectively fixing the first 36 and second tubular elements 37 to the enclosure 32. Sealing elements 39, particularly 0-rings, located between the fixing flanges 38 and enclosure 32 are adapted to prevent any contaminating agents present in the outer environment from entering the measuring chamber 5, and contaminating the powdered material.

The microwave sensor 4 comprises an input port 40 through which an electromagnetic field enters the microwave sensor 4, for example by means of a coaxial cable not shown. The coaxial cable can be connected to a launcher 41, by which the electromagnetic field enters the microwave sensor 4. The launcher 41 is of a known type, for example of the SMA or N type. The launcher 41 passes through the first wall 42 of the enclosure 32, the outer ring 35 and the second wall 43 of the enclosure 32. A threaded element 45, for example a grub screw, engages the second wall 43 so it comes in contact with the launcher 41. The threaded element 45 is made of an electrically conductive material, particularly metal, and it is located in contact with an end transversal surface of the launcher 41. The launcher 41 contributes to define, inside the microwave sensor 4, a turn or loop by which the electromagnetic field is introduced in the microwave sensor 4. The turn is defined, besides by the launcher 41, also by the connecting portion 44 and by the portions of the first wall 42 and second walls 43 located between the launcher 41 and the connecting portion 44. Thanks to the above described turn, the input electromagnetic field is current coupled with the microwave sensor 4. The threaded element 45 enables to establish an electrical contact between the launcher 41 and the second wall 43 of the enclosure 32.

The threaded element 45, which, as above described, engages an end transversal surface of the launcher 41, interacts with the launcher 41 without applying flexural stresses which can undesiderably deform the launcher 41. Moreover, the threaded element 45 comes in contact with the launcher 41 at a flat and relatively extended surface, this arrangement assures an accurate, robust and mechanically simple contact to be mechanically made. This fact ensures an optical impedance value of the input port 40. The microwave sensor 4 moreover comprises an output port 46 for enabling the electromagnetic field to output the microwave sensor 4 after having interacted with the powdered material. The output port 46 comprises a further launcher 47 by which the electromagnetic field exits the microwave sensor 4 to be supplied to an output coaxial cable, not shown. The further launcher 47, which can be of the SAM or N type, passes through the first wall 42 of enclosure 32, and after arrives in contact with the dielectric means, particularly with the outer ring 35. Unlike the launcher 41, the further launcher 47 however is not in contact with the second wall 43 of enclosure 32, but terminates in the outer ring 35. The further launcher 47 acts therefore as an antenna (probe) and it makes a voltage coupling between the microwave sensor 4 and the output coaxial cable. The output port 46, operating with a voltage, enables to increase the sensitivity of the microwave sensor 4.

The ends of the launcher 41 and of the further launcher 47 exiting the enclosure 32 to the respective coaxial cables are protected by respective protecting elements 48, each is provided with a passing hole 49 through which can pass the coaxial cable.

During the operation, when it is desired to measure the humidity, density, permittivity or another parameter of a powdered material, the control unit operates the conveying means 57; particularly the control unit operates the motor 8, which rotatively drives the input auger 7 in order to convey the powdered material in the measuring chamber 5. In the arrangement of Figure 3, during this step, the discharging means 51 (output auger 11) are kept stopped or however are driven but in a way to enable, in any case, the filling of the measuring chamber 5. The powdered material conveyed from the input auger 7 goes down by gravity inside the measuring chamber 5, which is progressively filled, to the level of the level sensor 14. When the level sensor 14 detects the measuring chamber 5 has been filled with the desired amount of powdered material, the conveying means 57 (the input auger 7) are stopped, in order to avoid that further powdered material is conveyed in the measuring chamber 5. The discharging means 51 (the output auger 11) are also kept stopped.

At least during the measuring step, the conveying means 57 and the discharging means 51 can be kept active (Figure 3) , for example, but not necessarily, keeping constant the material input and output flows (flow rates) so that inside the measuring chamber 5, the material advances at a controlled speed. With the device of Figure 3a, the handling means 61 can be equally kept active with an input or output material from the chamber 5 according to the needs. It is clear that also the steps of filling (or emptying) the measuring chamber 5 can be performed by the conveying 57 and discharging means 51 both operating (example of Figure 3) at speeds such to form different input/output material flows and fill/empty (also partially) the measuring chamber according to the needs. Therefore, the control unit enables the measure of the desired property by the microwave sensor 4. Particularly, the measure can be obtained by the ratio between the power exiting the microwave sensor 4 through the output port 46 and the power transmitted to the microwave sensor 4 through the input port 40. In this step, the temperature sensor 15, if present, can possibly measure the powdered material temperature.

In addition, it can be provided also a temperature sensor 58 of the microwave sensor 4 for monitoring the operating values.

As described before, the measure of the desired property by the microwave sensor 4 can be done while the powdered material is still inside the measuring chamber 5. The measure precision is further increased when, as in the shown example, the measuring chamber 5 is filled by conveying means which ensure an uniform compaction between consecutive batches of powdered material. After the powdered material has remained in the measuring chamber 5 for a predetermined time, selected to enable the measure by the microwave sensor 4, the control unit drives the discharging means 51, and particularly the further motor 12, which rotates the output auger 11, in order to remove the powdered material from the measuring chamber 5 and reintroduce the powdered material in the environment wherein such material is processed. The input auger 7 is kept stopped during this step. After a certain time, calculated so that the measuring chamber 5 is almost completely emptied, the dispenser 16 is operated which, through the passages 18, delivers a plurality of liquid and/or pressurized gas jets inside the measuring chamber 5. These jets enable to strip possible powdered material residues from the inner surface of a measuring chamber 5, which in turn are conveyed to the environment connected to the device 1 by the output auger 11. The measuring chamber 5 can be kept constantly cleaned. In this step, the measure is also taken by the sensor 4 when the measuring chamber 5 is empty for establishing the contamination degree and for possibly acting.

As said before, the property measure of the material can also be obtained with the same moving in the chamber, by suitably adjusting the speed of the conveying means 61 or anyway (Figure 3) of the conveying 57 and discharging means 51.

In a function of the materials of which the physical property must be determined, it can be used the first (static) or the second (dynamic) measuring arrangement. In a not shown version, instead of the input auger 7 and/or output auger 11, it is possible to use other conveying devices. For example, the output auger 11 can be substituted with a pneumatic conveyor possibly used in combination with a rotating valve transporting the powdered material in the pneumatic conveyor. The device 1 shown in Figures 1-3 is particularly adapted to be fixed to a flat wall defining the environment wherein the powdered material is processed. To this end, it is sufficient to make in the flat wall two openings, located at the input 6 and output ducts 10 respectively, and connect the device 1 to the flat wall by fixing elements inserted in the flange 2 holes 3. Figure 4 shows a device 101 according to an alternative version, wherein the parts common to the device 1 shown in Figures 1-3 are indicated with the same reference numbers and their detailed description will be omitted. The device 101 differs from device 1 because, instead of the flange 2, it comprises a tubular portion 20 adapted to be inserted in a transporting duct, inside which the powdered material is transported. The tubular portion 20 comprises a first 21 and second flange 22 which enable to fix the tubular portion 20 to an upstream duct portion and to a downstream duct portion respectively. The device 101 operates in the same way of device 1 and draws the powdered material from the environment defined inside the transporting duct, in which the powdered material is reintroduced when the microwave sensor 4 has measured the properties.

Locating the input auger 7 and the output auger 11 - or possible alternative conveying devices - inside the input 6 and output ducts 10 respectively, prevents the powdered material from contacting the outer environment during the measure. In other words, the device according to the invention, after having been fixed to the environment where the powdered material is processed, by the flange 2, the tubular portion 20 or another connecting element, enables to keep the powdered material in a closed environment, avoiding contamination of the powdered material during the measure. This is particularly important, from an easily understandable hygiene point of view, when the powdered material is a food or pharmaceutical product. The devices 1 and 101 shown in Figure 1-4 have an input and output openings separated one from the other. In other words, the powered material enters the devices 1 and 101 through the input opening 23, shown in Figure 1, and outputs from said devices through an output opening 24 different from the input opening 23.

Figure 5 shows a device 201 according to an alternative version comprising a measuring chamber 205 having just one opening 223, acting both as input and output of the powdered material. More generally, the embodiment of Figure 5 has an input for the material to be measured coincident with the discharging output of the same material from the measuring chamber 205. Obviously, in this second embodiment, the flow material direction 52 will have an alternate and opposed flow, first from the opening 223 to the chamber 205 and then from chamber 205 to opening 223.

Generally, just one input/output opening 223 will be present, however it could be assumed a further version provided with two or more openings all adapted to act as input and output for the material to be analysed. The device 201 comprises a connecting element, particularly a flange 202 adapted to be fixed a wall defining an environment where the powdered material is processed, for example a fluid bed apparatus, an atomizer or a transporting duct. The device 201 can be fixed to the environment wall where the powdered material is processed so that a main axis Z along which the measuring chamber 205 extends, is for example substantially vertical. Obviously, as an alternative, the opening 223 and the measuring chamber 205 can be oriented so that the velocity of the material main flow fills the same measuring chamber 205 or, anyway, a combination between the action of the gravity and the flow direction. The device 201 comprises a first 25 and second sleeves 26, between them a microwave sensor 204 is located, completely analogous to the microwave sensor 4 included in the devices shown in Figure 1-4. In the shown example, the microwave sensor 204 is of the cylindrical type but it could be anyone of the above mentioned kinds (with flat faces, multi faces, etc.). A cylindrical surface 27 is defined inside the first sleeve 25, second sleeve 26 and microwave sensor 204, laterally defining the measuring chamber 205. The measuring chamber 205 has also in this case an inner surface having a portion (in the shown example central along the envelope axis) which is defined by the same microwave sensor 204.

Then, there are ejecting means 60 adapted to take at least two positions, a rest position wherein they enables the material to enter the measuring chamber 25 and its detection by the sensor 204, and an ejecting position wherein they pour out the measuring chamber 205 substantially all the material before contained in it. In the shown embodiment, the ejecting means 60 comprise at least a sliding element 28, for example a pad movable inside the measuring chamber 205 parallelly to the main axis Z. The sliding element 28 can be moved by an actuator 29, for example a pneumatic cylinder. The sliding element 28 is defined, transversally to the main axis Z, by a transversal surface 30 defining an end wall of a measuring chamber 205 in the rest condition (Figure 5) . The device 201 comprises cleaning means which can comprise a scraping element 31 associated to the sliding element 28. The scraping element 31 can comprise a deformable element, for example a O-Ring arranged along the edge area of the sliding element 28 so that it is located between the sliding element 28 and the cylindrical surface 27 of the measuring chamber 205. Alternatively, the scraping element 31 can be defined by an edge of the sliding element 28.

In an area of the measuring chamber 205 located adjacent to the input/output opening, that is possibly the flange 201, there is a level sensor 214 analogue to the level sensor 14 described before. The device 201 can moreover comprise a temperature sensor, not shown, for detecting the material temperature and a temperature sensor for controlling the temperature of a microwave sensor 204. During the operation, when it is desired to measure a property of a powdered material, a control unit included in the device 201 or cooperating with it is arranged for driving the actuator 29 so that the latter moves (if it is not already in such position) the sliding element 28 in a retracted position (rest position) shown in Figure 5. Inside the measuring chamber 205 (or the first sleeve 25, the microwave sensor 204 and the second sleeve 26) the material is introduced by gravity and/or by the pressure exerted by the powdered material present inside the environment connected to the device 201. Alternatively, means for conveying the material in the chamber 205 different from or in addition to the gravity, such as suitable deflecting blades or other elements, can be foreseen. When the level sensor 204 detects that the powdered material has filled the measuring chamber 205 to the predetermined level, the measure is enabled by the microwave sensor 204. This measure is done in static conditions, because the sliding element 28 is kept in the retracted position. Also in this case it will be possible to decide if perform the measure with the material moving (almost static conditions) when the sliding element 28 advances from the retracted position to the material ejecting position.

In the almost static measure, once the detection has been made, the sliding element 28 advances during its ejection motion possibly at a speed greater than the one it has in the measuring step.

On the contrary, during the static measure condition, after a predetermined period of time has elapsed, sufficient for taking the desired property measure by the microwave sensor 204, the control unit drives the actuator 29, which drives the sliding element 28 along the main axis Z, to the input/output, that is to the flange 202. In this way, the measuring chamber 205 volume is gradually reduced and the powdered material present in the measuring chamber 205 is reintroduced in the environment where the powdered material is processed.

The sliding element 28 therefore acts as discharging means which removing the powdered material from the measuring chamber 205.

While the sliding element 28 moves towards the flange 202, the scraping element 31 slides along the cylindrical surface 27 of the measuring chamber 205 and removes from the cylindrical surface 27 possible powdered material residues adhering to it. The scraping element 31 enables to embody in a very simple way the cleaning means, because it can be driven by the same actuator 29 driving the discharging means and it does not require separated handling and controlling devices. Thanks to the only opening 223, the device 201 is very compact and it can be fixed to a wall of an apparatus where the powdered material is processed in a very simple way, by making a hole in the wall at the opening 223 and fixing the flange 202 to the wall, for example by welding.

Claims

C L A I M S

1. Device connectable to an environment wherein a flowable material is processed, comprising a measuring chamber (5; 205) adapted to be put in communication with said environment for receiving the flowable material, a microwave sensor (4; 204) for measuring a property of the flowable material contained in said measuring chamber (5; 205), handling means (61) for at least reintroducing the flowable material in the measuring chamber (5; 205) in said environment.

2. Device according to claim 1, wherein said handling means (61) comprise discharging means (51) for reintroducing the flowable material from the measuring chamber (5; 205) in said environment.

3. Device according to claim 1, moreover comprising enabling means (14; 214) for enabling the property measure by the microwave sensor (4; 204) when the flowable material has reached a predetermined amount in the measuring chamber (5; 205) .

4. Device according to claim 1, 2 or 3, wherein the handling means (61) comprise conveying means (57) arranged inside an inlet duct (6), for conveying the flowable material from said environment into the measuring chamber (5) .

5. Device according to claim 4, wherein the conveying means (57) draw the material from said environment and positively transfer it into the measuring chamber (5) , for example, at a predetermined flow rate, particularly the conveying means (57) being configurable in a plurality of operative conditions in a function of different input flow rates of the material.

6. Device according to claim 4, wherein the conveying means (57) draw the material from said environment and positively transfer it into the measuring chamber (5) along a flow direction (52) of the material with a flow substantially independent from the speed and/or pressure flow condition upstream of the conveying means (57) along the material flow direction (52) .

7. Device according to claim 4, 5 or 6, wherein the conveying means (57) are selected from a group comprising: an input auger conveyor (7), a pneumatic conveyor, a sliding element movable in the measuring chamber for thrusting the flowable material.

8. Device according to claim 4, wherein the measuring chamber (5) is located between the input duct (6) and an output duct (10) different from the input duct (6) along a material flow direction (52) .

9. Device according to claim 4, moreover comprising an output duct (10) adapted to allow the outflow of the material from the measuring chamber (5), the input (6) and output duct (6) being coincident.

10. Device according to claim 4, wherein the conveying means (57) and discharging means (51) are coincident, particularly the handling means (61) being reversibly configurable between a charging condition of the measuring chamber (5) defined by the conveying means (57) and a discharging condition of the measuring chamber (5) defined by said discharging means (51) .

11. Device according to one of claims 1-7, wherein the measuring chamber (205) has an opening (223) adapted to terminate in said environment, said opening (223) being configured so that the flowable material enters the measuring chamber (205) , and exits the measuring chamber (205), through said opening (223).

12. Device according to the preceding claim, wherein the discharging means (51) comprise a sliding element (28) movable between at least one retracted position wherein it allows the input of the material through the opening (223) in the measuring chamber (205) and an extracted position wherein it does not allow this input, particularly the sliding element being movable from the retracted position to the extracted position for ejecting the material contained in the measuring chamber (205) .

13. Device according to the preceding claim, wherein the sliding element has sizes transversal with respect to its own moving axis substantially coincident with the transversal sizes of the measuring chamber (205) , particularly the sliding element being at least partially housed in the measuring chamber (205) .

14. Device according to claim 11, wherein the discharging means (51) are reversibly configurable between a discharging condition wherein they reintroduce the flowable material from the measuring chamber (5; 205) in said environment and a charging condition wherein they introduce the flowable material from the environment in said measuring chamber (5; 205) .

15. Device according to anyone of the preceding claims, wherein the discharging means (51) are positive for a flow inside the measuring chamber (205) for allowing the ejection of the material contained in the measuring chamber (205) after a displacement between a retracted position and an extracted position.

16. Device according to anyone of the preceding claims, wherein said discharging means (51) comprise handling means (11; 28) acting on the flowable material for transferring the flowable material from the measuring chamber (5; 205) to said environment.

17. Device according to anyone of the preceding claims, wherein the discharging means (51) draw the material from the measuring chamber (5) and actively transfer it into said environment along a material flow direction (52) with a flow substantially independent from the speed and/or pressure material condition upstream of the discharging means (51) along the material flow direction (52) .

18. Device according to anyone of the preceding claims, wherein the handling means are selected from a group comprising: an auger conveyor, a pneumatic conveyor, a sliding element (28) movable in the measuring chamber (205) for thrusting the flowable material at least to said environment.

19. Device according to anyone of the preceding claims, wherein the microwave sensor (4; 104) at least partially defines the measuring chamber (5; 205) .

20. Device according to anyone of the preceding claims, moreover comprising cleaning means (16; 31) for removing any residues of the flowable material from the measuring chamber (5; 205) .

21. Device according to claim 20, wherein the cleaning means are selected in a group comprising: a supplying element (16) for supplying a liquid, a pressurized gas or a mixture of liquid and gas in the measuring chamber (5) , a sliding scraping element (31) in contact with an inner surface (27) of the measuring chamber (205), a brush.

22. Device according to claim 20, wherein a control unit receives the material temperature in the measuring chamber (5; 205) and is configured for adjusting a temperature of the cleaning means according to a predetermined delta, that can be zero with respect to the material temperature.

23. Device according to anyone of the preceding claims, wherein the microwave sensor (4) comprises a cylindrical microwave resonator, an input port (40) for allowing an electromagnetic field to enter the microwave resonator, an output port (46) for allowing the electromagnetic field to output the microwave resonator, a turn device being associated to the input port (40) and an antenna device being associated to the output port (46).

24. Method for measuring a parameter of a material by a device connectable to an environment wherein a flowable material is processed, comprising a measuring chamber

(5; 205) adapted to be put in communication with said environment for receiving the flowable material, a microwave sensor (4; 204) for measuring a property of the flowable material contained in the measuring chamber

(5; 205) , discharging means (51) for reintroducing the flowable material from the measuring chamber (5; 205) in said environment, the method comprising the following steps of: supplying an amount of the material to be analyzed to the measuring chamber (5; 205) ; measuring a parameter of said material by the microwave sensor (4 ) ; ejecting said material from the measuring chamber (5; 205 ) .

25. Method according to the preceding claim, wherein the step of supplying an amount of the material to be analyzed comprises a sub-step of conveying said material from a source to the measuring chamber (5) by conveying means (57), said conveyance being made by a positive transfer of the material from the source to the measuring chamber (5) .

26. Method according to claim 24, wherein the steps of supplying, measuring, ejecting are temporally consecutive.

27. Method according to claim 24, wherein the steps of supplying, measuring, ejecting are at least partially temporally overlapped, particularly the step of measuring being performed during at least the last part of the supplying step and the first part of the ejection step.

28. Method according to claim 24, moreover comprising another measuring step by the microwave sensor (4, 204) when the chamber is emptied of the material, particularly for determining a contamination degree of the measuring chamber (5, 205) and/or of the sensor (4, 204) .

29. Method according to claim 24, wherein the steps of supplying an amount of a material to be analyzed to the measuring chamber (205) and of ejecting said material from the measuring chamber (205) are performed through the same opening (223) connecting said measuring chamber (205) to the environment, particularly said opening (223) being the only opening connecting the measuring chamber (205) to the environment.