Ultrasonic measuring device for in-line measurement of the homogeneity of fluid products in dispersion units

Abstract

A measuring device (1) for in-line measuring the homogeneity of a fluid product in a dispersion unit (100), comprising: - a tubular device (2) that can be placed at the outlet (100b) of said distribution unit (100), said tubular device (2) having an internal cavity (3) through which the fluid product received from said distribution unit (100) passes; - a plurality of ultrasonic sensors (4) attached to the tubular device (2), The measuring device (1), wherein the internal cavity (3) has a variable diameter over the length of the tubular device (2), and the internal cavity (3) has at least one first tube (31) having a tapered development from the inlet (2a) of the tubular device (2) towards the outlet (2b) of the tubular device (2).

Description

[Technical Field]

[0001] The present invention relates to a measuring device for in-line measuring the homogeneity of a fluid product in a dispersion unit.

[0002] The invention proposed here can be used in the food industry, in particular in the dairy sector, or in the chemical, pharmaceutical or cosmetic industries.

[0003] The present invention can also be used in manufacturing applications where homogenization is a step in the production process.

[0004] Consider, for example, the production of carbon-based nanostructured materials such as graphene and carbon nanotubes, or the disruption of yeast, algae, and microorganisms for the production of intracellular materials. [Background technology]

[0005] In various currently known embodiments, the homogenizing device comprises a high pressure pump and a homogenizing valve acting on the fluid product, - In the case of emulsions, grinding the particles of the fluid to make them uniform in size and reduce the variability in average size and distribution in order to stabilize the product and extend its shelf life; - disrupting cell membranes to facilitate the extraction of active ingredients in pharmaceutical applications; - A homogenization valve for chemical applications and for modifying the structure of particles in the case of cellulose or single-cell organisms.

[0006] For most products, the main parameters that define the level of homogenization are the mean particle size and the standard deviation.

[0007] In known solutions, the pressure in the homogenizer is regulated as explained below.

[0008] First, the optimum mean particle size and standard deviation for a particular fluid product are determined experimentally. Then, the pressure required to obtain particles exhibiting the calculated parameters is applied. The pressure is maintained at: - Periodically adjust the pressure value by manual intervention, - By using a feedback system that takes as input the pressure level detected in the fluid product and forces the output to follow a set value.

[0009] Both methods act directly on the homogenization pressure.

[0010] Nevertheless, the homogenization pressure cannot be considered a reliable real-time indicator of the actual homogenization level. In fact, even if the pressure and fluid product are identical, different homogenization levels may be obtained due to, for example, variations occurring in new product fed to the equipment and / or wear of parts.

[0011] Known methods cannot track differences in the fluid products fed into the homogenizer.

[0012] Furthermore, known methods do not take into account changes caused to the fluid product by non-ideal parts.

[0013] These situations are typically addressed by designing a homogenizer that can guarantee a homogenization level above a pre-set threshold corresponding to the most adverse conditions.

[0014] Large homogenizers increase the risk of mechanical stress on some components, which can shorten their lifespan.

[0015] Furthermore, applying a higher pressure value than desired consumes energy.

[0016] Finally, applying a higher pressure value than required does not guarantee that the desired homogenization level will be reached, as it will cause a temperature rise that can damage the fluid product. Some of the product may even be discarded due to thermal damage.

[0017] Document EP 1121973 A1 discloses a system for monitoring the dispersion produced in a dispersion unit, in particular its homogeneity, and it is proposed to couple at least one measuring sensor to the dispersion unit in order to achieve in-line measurement of the homogeneity of the dispersion.

[0018] The sensors used in this document may be ultrasonic sensors that are immersed in or in contact with the fluid product, and therefore the sensors are prone to contamination and unreliability, and are also susceptible to damage from the high temperatures of the fluid product. Summary of the Invention

[0019] In this context, the object of the present invention is to propose a measuring device for in-line measuring the homogeneity of a fluid product in a dispersion unit, which overcomes the problems of the prior art mentioned above.

[0020] In particular, the object of the invention is to propose a measuring device for in-line measuring the homogeneity of a fluid product in a dispersion unit, which achieves a higher measurement reliability than known solutions.

[0021] It is a further object of the present invention to provide a measurement device for measuring the homogeneity of a fluid product in-line within a dispersion unit without affecting the fluid product.

[0022] Another object of the invention is to propose a measuring device for in-line measuring the homogeneity of a fluid product in a dispersion unit, which is robust, unlikely to wear out over time and easy to clean.

[0023] Another object of the invention is to propose a measuring device for in-line measurement of the homogeneity of a fluid product in a dispersion unit, which allows preventive maintenance operations to be planned more efficiently.

[0024] The stated technical problem and the identified objectives are substantially achieved by a measurement device for measuring the homogeneity of a fluid product in-line in a dispersion unit, the measurement device comprising: - a tubular device positionable at the outlet of the dispersion unit, the tubular device having an internal cavity for the passage of the fluid product received from the dispersion unit; a plurality of ultrasonic sensors attached to the tubular device; The internal cavity has a variable diameter over the length of the tubular device, and the internal cavity has at least one first tube having a tapered progression from the inlet of the tubular device to the outlet of the tubular device.

[0025] Preferably, a plurality of ultrasonic sensors are distributed along the length of the tubular device.

[0026] According to one aspect of the invention, the first tube of the internal cavity is formed by a plurality of substantially cylindrical sections joined by frusto-conical sections, the cylindrical sections having corresponding diameters that decrease from the inlet to the outlet of the tubular device.

[0027] Preferably, the internal cavity has a second tube starting from the first tube and terminating at the outlet of the tubular device, in particular the second tube having a tapered development from the outlet of the tubular device towards the first tube.

[0028] In particular, the second tube of the internal cavity consists of a frusto-conical section connecting the first tube to the outlet of the tubular device.

[0029] According to one aspect of the present invention, a tubular device includes a first tube and a second tube, the first tube being coaxial with and disposed within the second tube, and an interior cavity being defined by the interior surface of the first tube.

[0030] Preferably, the inner surface of the first tube has a tapered development partly from the inlet to the outlet of the tubular device so as to define a corresponding tapered development of the first lumen of the internal cavity.

[0031] According to one aspect of the present invention, a plurality of ultrasonic sensors are disposed between the first tube and the second tube.

[0032] Preferably, the first tube has a plurality of housings for receiving the plurality of ultrasonic sensors, the housings being provided as internal recesses in the outer surface of the first tube.

[0033] In one embodiment of the present invention, a plurality of ultrasonic sensors are adhered to the first tube.

[0034] In another embodiment of the present invention, a plurality of ultrasonic sensors are mounted on the outside of the second tube.

[0035] For example, the ultrasonic sensors are screwed to the second tube.

[0036] Preferably, the first tube is made of a plastic material and the second tube is made of a metal material.

[0037] More preferably, the first tube is made of PEEK or PTFE.

[0038] The second tube is made of stainless steel.

[0039] According to one aspect of the invention, the tubular device includes a heat exchanger for cooling the plurality of ultrasonic sensors.

[0040] Preferably, the heat exchanger is a conduit for a cooling fluid, the conduit passing through the tubular device over its entire length and parallel to the longitudinal axis of the tubular device. [Brief explanation of the drawings]

[0041] Further features and advantages of the present invention will become more fully apparent from the non-limiting description of preferred but non-exclusive embodiments of a measurement device for in-line measuring the homogeneity of a fluid product in a dispersion unit, as shown in the accompanying drawings. [Figure 1-2] 1 shows two different embodiments of a measurement device for in-line measurement of the homogeneity of a fluid product according to the present invention; [Figure 3] 1 shows waveforms of measurement signals received by four sensors in experimental tests carried out to select the optimum material for the first tube of the measuring device. [Figure 4] 1-2 at the outlet of the distribution unit. DETAILED DESCRIPTION OF THE INVENTION

[0042] Referring to the drawings, the number 100 denotes a dispersion unit. The dispersion unit 100 has an inlet 100a and an outlet 101b for the fluid product.

[0043] For example, the dispersion unit 100 is a high-pressure homogenizer that includes a positive displacement piston pump and a homogenization valve disposed downstream of the positive displacement piston pump.

[0044] In particular, the high pressure homogenizer 100 operates at pressures up to 4000 bar.

[0045] Number 1 denotes a measuring device for measuring the homogeneity of the fluid product in-line within the dispersion unit 100 .

[0046] The measurement device 1 comprises a tubular device 2 arranged at the outlet 100 b of the dispersion unit 100 .

[0047] The tubular device 2 has an inlet 2a for receiving the homogenized fluid product from the dispersion unit 100, and an outlet 2b.

[0048] The tubular device 2 has an internal cavity 3 for the passage of the fluid product received from the dispersion unit 100 .

[0049] An internal cavity 3 extends from the inlet 2a to the outlet 2b of the tubular device 2.

[0050] The diameter of the internal cavity 3 at the inlet 2a and outlet 2b of the tubular device 2 is substantially the same.

[0051] Uniquely, the internal cavity 3 has a variable diameter over the length of the tubular device 2 .

[0052] In particular, the internal cavity 3 has at least one first tube 31 having a tapered development from the inlet 2 a towards the outlet 2 b of the tubular device 2 .

[0053] In other words, the first tube 31 has a shape that converges from the inlet 2 a towards the outlet 2 b of the tubular device 2 .

[0054] Preferably, the first tube 31 of the internal cavity 3 is formed by a plurality of substantially cylindrical sections 310 joined by frusto-conical sections 311 .

[0055] The plurality of cylindrical portions 310 have corresponding diameters that decrease from the inlet 2 a to the outlet 2 b of the tubular device 2 .

[0056] In the illustrated embodiment, the first tube 31 comprises five cylindrical sections 310 joined by four frusto-conical sections 311 .

[0057] The internal cavity 3 preferably has a second tube 32 starting from the first tube 31 and terminating at the outlet 2 b of the tubular device 2 .

[0058] The second tube 32 has a tapered development from the outlet 2 b of the tubular device 2 towards the first tube 31 .

[0059] In other words, the second tube 32 has a shape that converges from the outlet 2 b of the tubular device 2 towards the first tube 31 .

[0060] In particular, the second tube 32 consists of a frusto-conical portion 321 that connects the first tube 31 to the outlet 2 b of the tubular device 2 .

[0061] In particular, the last cylindrical section 310 of the first tube 31 is connected to the frusto-conical section 321 of the second tube 32 .

[0062] The measuring apparatus 1 further comprises a number of ultrasonic sensors 4 attached to the tubular device 2 and configured to detect ultrasonic waves.

[0063] According to the illustrated embodiment, the tubular device 2 comprises a first tube 5 and a second tube 6 .

[0064] The first tube 5 is coaxial with and disposed inside the second tube 6 .

[0065] The first tube 5 defines an internal cavity 3. In particular, the internal cavity 3 is defined by an inner surface 5a of the first tube 5.

[0066] In particular, the inner surface 5 a of the first tube 5 has a tapered development from the inlet 2 a towards the outlet 2 b of the tubular device 2 so as to define in part a corresponding tapered development of the first lumen 31 of the internal cavity 3 .

[0067] According to one embodiment of the present invention, a plurality of ultrasonic sensors 4 are arranged between a first tube 5 and a second tube 6 .

[0068] Preferably, multiple ultrasonic sensors 4 are distributed along the length of the tubular device 2 .

[0069] According to the embodiment illustrated here, the first tube 5 comprises a plurality of housings 7 for receiving a plurality of ultrasonic sensors 4 .

[0070] Preferably, the housings 7 are provided as inner recesses in the outer surface 5 b of the first tube 5 .

[0071] According to one embodiment of the present invention, the ultrasonic sensors 4 are glued to the first tube 5. In particular, they are arranged inside the housings 7 and glued to the outer surface 5b of the first tube 5.

[0072] According to another embodiment of the present invention (not shown), a plurality of ultrasonic sensors 4 are mounted on the exterior of the second tube 6 .

[0073] For example, a plurality of ultrasonic sensors 4 are screwed onto the outside of the second tube 6 so as to reach close to the first tube 5 .

[0074] Preferably, in this embodiment, an ultrasound gel is deposited between the plurality of ultrasound sensors 4 and the first tube 5 to ensure signal transmission.

[0075] Preferably, the measuring device 1 has an electrical connector attached to the second tube 6. The electrical connector is used to connect the ultrasonic sensor 4.

[0076] 1, each cylindrical portion 310 is coupled to one ultrasonic sensor 4. The ultrasonic sensor 4 is located inside a housing 7 provided in a portion of the first tube 5 that surrounds the corresponding cylindrical portion 310.

[0077] In this embodiment, referred to as "pulse-echo," the ultrasonic sensors 4 are configured to generate and detect ultrasonic waves. In other words, the ultrasonic sensors 4 function as emitters and receivers.

[0078] The waves generated by the plurality of ultrasonic sensors 4 pass through the fluid product flowing within the internal cavity 3 and are reflected back by a second tube 6 made of metal.

[0079] Alternatively, a reflector may be attached to the opposite side of the housing 7 relative to the internal cavity 3 to increase the reflection of ultrasound waves.

[0080] According to another embodiment of the present invention shown in Figure 2, each cylindrical portion 310 is coupled to one of the aforementioned plurality of ultrasonic sensors 4 (referred to herein as a "receiver") and to another ultrasonic sensor 14 (referred to herein as an "emitter") configured to generate ultrasonic waves. The receiver 4 and the emitter 14 are respectively disposed within two housings 7 located on opposite sides of the internal cavity 3. The two housings 7 are provided in portions of the first tube 5 surrounding the corresponding cylindrical portion 310, but on different sides with respect to the flow of the fluid product.

[0081] In this embodiment, referred to as "transmission," the waves generated by the emitter 14 pass through the fluid product flowing within the internal cavity 3 and are detected by the receiver 4.

[0082] According to one aspect of the present invention, the first tube 5 is made of a plastic material, so that ultrasound can pass through the first tube 5.

[0083] In a preferred embodiment, the first tube 5 is made of PEEK.

[0084] Alternatively, the first tube 5 is made of PTFE.

[0085] Experimental tests were carried out to select the optimum material for the first tube 5 .

[0086] The test consisted of creating four different tubular sample sections, each made of a different material to simulate the first tube 5 .

[0087] Each sample section is fitted with its own ultrasonic sensor, a piezoelectric ceramic sensor with a resonant frequency of 5 MHz, which is screwed to the corresponding sample section.

[0088] These are the four tubular sample sections that were prepared for testing: - First sample part: 2 mm thick tube made of AISI 316L (from the inner cavity to the corresponding screwed sensor) - Second sample part: PTFE tube (from the inner cavity to the corresponding screwed sensor) 10 mm thick - Third sample part: 10 mm thick tube made of PEEK (from the inner cavity to the corresponding screwed sensor) - Fourth sample part: a tube made of AISI 316L and 4 mm thick (from the inner cavity to the corresponding screwed sensor).

[0089] In effect, these sample parts are simplified versions (with only the first tube 5) of tubular devices 2 with a pulse-echo arrangement in which multiple ultrasonic sensors act as emitters and receivers.

[0090] The first three samples have different thicknesses, chosen to obtain adequate mechanical resistance to withstand the internal pressure of 40 bar inside the tube. The fluid in the cavity is tap water at room temperature.

[0091] The third sample (PEEK) was the best choice because the signal after the first reflection was well distinguished from the noise.

[0092] PEEK is the best choice as it combines high mechanical resistance with chemical inertness, compatibility with food-grade / pharmaceutical substances, resistance to high sterilization temperatures, and transparency to ultrasound.

[0093] Additionally, a fourth sample is included to compare how the signal transmits through a thicker (i.e., twice as thick) AISI 316L than the first sample. In the fourth sample, the thicker AISI 316L significantly attenuates the transmission of the ultrasonic signal, causing the first reflection of the signal to be affected by noise.

[0094] The measurement signals received by the four sensors are shown in Figure 3 for easy comparison. - S1 refers to the first sample portion, - S2 refers to the second sample portion, - S3 refers to the third sample part, - S4 refers to the fourth sample part.

[0095] The second tube 6 is made of a metal material, for example, stainless steel, so that the ultrasonic waves are reflected by the second tube 6 and maintained within the tubular device 2.

[0096] According to one aspect of the invention, the tubular device 2 comprises a heat exchanger 8 for cooling the ultrasonic sensor 4 .

[0097] Preferably, the heat exchanger 8 is a conduit for the passage of a cooling fluid.

[0098] Preferably, the conduit 8 passes through the tubular device 2 over its entire length and has a main channel parallel to the longitudinal axis AA of the tubular device 2 .

[0099] According to one embodiment of the present invention, the conduit 8 has an inlet provided in the second tube 6 corresponding to the housing 7 located closer to the inlet 2a of the tubular device 2, and an outlet provided in the second tube 6 corresponding to the housing 7 located closer to the outlet 2b of the tubular device 2.

[0100] Alternatively, the inlet of the conduit 8 is closer to the outlet 2b of the tubular device 2 and the outlet of the conduit 8 is closer to the inlet 2a of the tubular device 2. In particular, the conduit 8 is supplied with air having a temperature of 5°C-40°C.

[0101] The air flowing through the conduit 8 helps to maintain the temperature of the ultrasonic sensor 4 under control, regardless of the temperature of the fluid product flowing through the internal cavity 3 .

[0102] This is advantageous both during normal operation of the dispersion unit 100 and during sterilization cycles where the tubular device 2 may reach high temperatures (e.g., 130°C) which may affect the reliability of or even damage the ultrasonic sensor 4.

[0103] Furthermore, in embodiments in which the ultrasonic sensors 4 are glued to the first tube 5, high temperatures may cause the sensors 4 to peel off from the first tube 5, creating an air gap between the sensors 4 and the first tube 5, thus disrupting signal transmission.

[0104] The ultrasonic sensors 4 are configured to receive ultrasonic waves having a frequency between 2 MHz and 20 MHz.

[0105] Preferably, the ultrasonic sensors 4 are selected to operate at different frequencies to detect ultrasonic waves passing through fluid products having different acoustic impedances.

[0106] The signals detected by the plurality of ultrasonic sensors 4 can be used to control the pressure of the fluid product within the dispersion unit 100 .

[0107] The features of the measuring device for in-line measuring the homogeneity of a fluid product in a dispersion unit according to the invention, as well as the advantages, become apparent from the above description.

[0108] Since the ultrasonic waves are distributed along the entire length of the tubular device, detection is performed simultaneously at multiple measurement points of the fluid product stream.

[0109] Therefore, the reliability of this detection is higher than detection at a single point or single sample of the fluid product. Redundancy is also advantageous in the event that one or more sensors are damaged.

[0110] Furthermore, by locating the ultrasonic sensors on the outer surface of the first tube, direct contact with the fluid product flowing through the inner cavity is avoided, which leads to a beneficial hygienic design of the tubular device.

[0111] Additionally, in embodiments where multiple ultrasonic sensors are bonded to the first tube, there is substantially no air within the housing of the ultrasonic sensors, which ensures signal quality, as air attenuates ultrasonic waves.

[0112] Furthermore, in embodiments in which the ultrasonic sensors are bonded to the first tube, the ultrasonic sensors are substantially maintained in their position during assembly and disassembly of the tubular device. This is ensured by locating them within an internal recess on the outer surface of the first tube. Indeed, this placement also protects the ultrasonic sensors from damage.

[0113] In the embodiment in which the ultrasonic sensors are glued to the first tube, the ultrasonic sensors are not mechanically coupled to the stainless steel second tube. Therefore, there is no risk of particles (i.e., dust) accumulating between the second tube and the ultrasonic sensors. Furthermore, the second tube is substantially smooth and has only one electrical connector. Therefore, the exterior surface of the second tube is easy to clean. [Prior art documents] [Patent documents]

[0114] [Patent Document 1] EP 1121973 A1

Claims

1. A measuring device (1) for in-line measuring the homogeneity of a fluid product in a dispersion unit (100), comprising: a tubular device (2) that can be placed at the outlet (100b) of said distribution unit (100), said tubular device (2) having an internal cavity (3) for the passage of said fluid product received from said distribution unit (100); a plurality of ultrasonic sensors (4) attached to said tubular device (2), The internal cavity (3) has a variable diameter over the length of the tubular device (2), the internal cavity (3) having at least one first tube (31) having a tapered development from the inlet (2a) of the tubular device (2) towards the outlet (2b) of the tubular device (2).

2. 2. The measuring device (1) of claim 1, wherein the first tube (31) of the internal cavity (3) is formed by a plurality of substantially cylindrical sections (310) joined by truncated conical sections (311), the plurality of cylindrical sections (310) having corresponding diameters that decrease from the inlet (2a) towards the outlet (2b) of the tubular device (2).

3. 3. The measuring device (1) according to claim 2, wherein the internal cavity (3) has a second tube (32) starting from the first tube (31) and ending at the outlet (2b) of the tubular device (2), the second tube (32) having a tapered development from the outlet (2b) of the tubular device (2) towards the first tube (31).

4. 4. The measuring device (1) according to claim 3, wherein the second tube (32) of the internal cavity (3) consists of a truncated cone section (320) connecting the first tube (31) to the outlet (2b) of the tubular device (2).

5. 5. The measuring device (1) according to claim 1, wherein the tubular device (2) comprises a first tube (5) and a second tube (6), the first tube (5) being coaxial with and arranged inside the second tube (6), and the internal cavity (3) being defined by an inner surface (5a) of the first tube (5).

6. 6. The measuring device (1) according to claim 5, wherein the inner surface (5a) of the first tube (5) has a tapered development partly from the inlet (2a) towards the outlet (2b) of the tubular device (2) so as to define a corresponding tapered development of the first pipe (31) of the internal cavity (3).

7. 7. The measuring device (1) according to claim 5 or 6, wherein the ultrasonic sensors (4) are arranged between the first tube (5) and the second tube (6).

8. 8. The measuring device (1) of claim 7, wherein the first tube (5) has a plurality of housings (7) for receiving the plurality of ultrasonic sensors (4), the plurality of housings (7) being provided as inner recesses in the outer surface (5b) of the first tube (5).

9. 9. The measuring device (1) according to claim 7 or 8, wherein the ultrasonic sensors (4) are glued to the first tube (5).

10. 7. The measuring device (1) according to claim 5 or 6, wherein the ultrasonic sensors (4) are mounted on the exterior of the second tube (6).

11. 11. The measuring device (1) according to claim 10, wherein the ultrasonic sensors (4) are fixed to the second tube (6) by screws.

12. 12. Measuring device (1) according to any one of claims 5 to 11, wherein the first tube (5) is made of a plastic material and the second tube (6) is made of a metal material.

13. 13. Measuring device (1) according to claim 12, wherein the first tube (5) is made of PEEK or PTFE.

14. 14. Measuring device (1) according to claim 12 or 13, wherein the second tube (6) is made of stainless steel.

15. 15. The measuring device (1) according to any one of the preceding claims, wherein the tubular device (2) comprises a heat exchanger (8) for cooling the plurality of ultrasonic sensors (4).

16. 16. The measuring device (1) according to claim 15, wherein the heat exchanger (8) is a conduit for a cooling fluid, the conduit (8) passing through the tubular device (2) over its entire length and parallel to the longitudinal axis (A-A) of the tubular device (2).

17. 17. The measuring device (1) according to any one of the preceding claims, wherein the plurality of ultrasonic sensors (4) are arranged along the length of the tubular device (2).

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