METHOD AND DEVICE FOR DETERMINING THE MATERIAL MOISTURE OF A MATERIAL

Description

[0001] The invention relates to a method for determining the material moisture content of a pyrotechnic and / or explosive substance.

[0002] Furthermore, the invention relates to a device for determining the material moisture content of a pyrotechnic and / or explosive substance.

[0003] The production of most industrial powders and bulk materials is a sensitive process in which even minor changes in material parameters can lead to significant deviations in quality. One of the most important material variables is material moisture. During the manufacturing process, fluctuations in material moisture content can jeopardize the desired product quality.

[0004] To achieve the desired moisture content, such materials are dried. Various drying processes are available, such as air drying (dehydration or aging), freeze drying, microwave drying, condensation processes, etc.

[0005] Fundamentally, every drying process requires certain input variables, such as moisture content before and at the end of the drying process, in order to adjust process parameters such as the required energy. The residual moisture content of a material can be determined using various methods, with a basic distinction being made between direct and indirect drying processes.

[0006] In the drying-weighing method, which is a direct method, the sample is dried, and the moisture content of the sample is determined via the loss of mass. The disadvantages of this method are the long drying time and the fact that the sample must be removed, which is destructive. Such methods are described, for example, in K. Kuper: Materialfeuchtemessung,

[0007] Expert Verlag, 1997 or in W. Lück: Humidity, Basics, Measuring, Control, Oldenbourg Verlag, 1964.

[0008] Indirect methods examine changes in material properties related to moisture. Typical properties include weight, volume, electrical conductivity, dielectric constant, etc. Low-frequency methods and methods based on conductivity measurements are not non-destructive compared to high-frequency methods in the microwave range. Another disadvantage is that low-frequency methods are more susceptible to interference due to the ionic influence of water. A key advantage of indirect methods is that measurement times are reduced by orders of magnitude compared to direct methods.

[0009] Of the indirect measurement methods, those based on microwaves are the most suitable.

[0010] Microwave measurement methods for determining material moisture content are dielectric methods. These are based on the dielectric properties of water, which is a polar molecule, meaning that the centers of charge do not coincide locally within the molecule. Therefore, the water molecule aligns itself in a preferred direction in an externally applied field. In other words, water molecules are polarizable. When such an alternating electromagnetic field is applied, the molecules rotate at the frequency of the field. This phenomenon is also called orientation polarization. This dielectric effect is so pronounced in water that even small amounts of water can be reliably detected.

[0011] J. MELLMANN ET AL: "Development of the Heat and Mass Transfer Model for Mixed-Flow Grain Dryer," Proceedings of the 17th World Congress, The International Federation of Automatic Control, July 6, 2008 (2008-07-06), pages 9591-9595, already discloses the measurement of grain moisture content at the inlet of a dryer. The moisture content of the dried grain is continuously recorded at the dryer outlet using an online microwave moisture sensor. Additionally, samples are taken from the grain at the outlet to analyze the moisture content.

[0012] WO 2018 / 141630 A1 proposes a drying chamber equipped with a magnetron. This magnetron can then apply the required microwave radiation to the explosive to be dried, thus heating it.

[0013] CN 101 221 009 A relates to a method for microwave drying of a detonator.

[0014] DE 10 2005 013647 B3 relates to a method for measuring the moisture content of a material using a microwave resonator.

[0015] CH 604 163 A5 discloses a microwave moisture meter for measuring moisture content.

[0016] DE 102 04 328 A1 discloses the use of microwaves in the spinning industry to determine the sliver dimensions of an elongated, essentially reversed fiber strand. A microwave sensor is connected downstream of a drafting system. This sensor can not only perform sliver runout control but can also be used to calibrate another sensor that operates with microwaves.

[0017] DE 42 24 128 A1 discloses a method for determining the moisture content of clay-containing material and similar moldable masses for the production of ceramic products and a feeding device on which the method is carried out.

[0018] From DE 102 46 260 A1 a device for regulating moisture, in particular for regulating the moisture of a bulk material, for example wheat in a mill system, is known.

[0019] DE 91 06 191 U1 discloses a device for measuring the moisture content of coarse- and fine-grained bulk materials in online operation. The device comprises a microwave measuring sensor, a signal processing unit, and a control computer. To correct the measurement signal, the temperature and conductivity of the material being measured are measured by a temperature sensor and a conductivity sensor. The disadvantage of this approach is that two additional measured variables must be measured online by two additional sensors. This has proven impractical.

[0020] Based on this, the object of the invention is to create a method with which the material moisture content of a pyrotechnic and / or explosive substance can be reliably determined.

[0021] This object is achieved by the features of claim 1 and claim 8. Advantageous embodiments and further developments are the subject of the respective subclaims.

[0022] The pyrotechnic and / or explosive substance is hereinafter also referred to as "material", which is preferably a bulk material or solid.

[0023] The method is carried out by means of a device comprising a first and a second microwave sensor and at least one control and evaluation device.

[0024] Preferably, the method may provide that the step of referencing the material with a referencing device takes place offline.

[0025] Furthermore, it can be provided that the referencing device for referencing the material is arranged offline.

[0026] The dielectric material constant of the material sample is determined as a function of the material moisture using a microwave measuring device.

[0027] After determining the dielectric material constant of the material sample, it is saved.

[0028] The step of determining the material moisture content of the material is carried out by a control and evaluation device based on the dielectric material constants previously measured online.

[0029] Material K is a pyrotechnic and / or explosive substance.

[0030] The use of microwave measuring sensors has the advantage, thanks to the low transmission energy used, that there is no heating or change in the material, thus minimizing the risk of the material or the measuring process itself being affected.

[0031] The determination of the dielectric material constants can be carried out, for example, by a high-frequency measurement method using the Bischoff method or a Vincent method as a line-based 2-port method with a vector network analyzer.

[0032] Online, in the context of the invention, means that this occurs along a production, drying, transport, or other line. Offline means that measuring or the like takes place independently of such a line.

[0033] The measuring sensor to be calibrated can be either a resonant single-port or a transmissive double-port microwave measuring sensor, which measures the dielectric constants of the material and thus the moisture content without contact. The microwave sensor is designed to allow real-time measurement and evaluation. The measurement settings and control of the process parameters can be performed via microcontrollers embedded in the evaluation and control unit.

[0034] The referencing step can, for example, take place using a drying and weighing process.

[0035] The inventive design enables contactless and non-destructive real-time measurement of residual moisture. Thus, real-time moisture measurement via the electrical material characteristics is possible. Using the inventive method and device, process adjustment and validation of residual moisture are possible.

[0036] According to the invention, the method comprises the following steps: online measurement of the dielectric material constant of the material using a second microwave sensor; re-determination of the material moisture content of the material based on the previously measured dielectric material constant online.

[0037] In an embodiment of the device, it is provided that the device has a second microwave sensor arranged online for measuring the dielectric material constants of the material, and the control and evaluation device is set up to determine the material moisture content of the material on the basis of the previously measured dielectric material constants online.

[0038] The step of re-determining the material moisture content of the material based on the previously measured online dielectric material constants is carried out by the control and evaluation device.

[0039] The steps of online measurement using the second microwave sensor and re-determination of the material moisture content take place after the initial determination of the material moisture content.

[0040] This ensures that a further measurement is taken and the material moisture is determined.

[0041] In an embodiment of the method, it can be provided that the method further comprises the following step: validating the material moisture on the basis of the dielectric material constants measured by the second microwave sensor by the control and evaluation device.

[0042] For this purpose, the material moisture content is validated based on the two measured values. The control and evaluation unit is configured to perform such a validation. To do so, it compares the first and second dielectric material constants measured online. This ratios the first and second determined material moisture values, i.e., compares them.

[0043] In an advantageous development of the device, it can be provided that the control and evaluation device is designed to validate the material moisture.

[0044] This ensures that the measured moisture content of the material is determined correctly. Any deviations or errors are detected.

[0045] The validation step takes place after the material moisture content of the material has been determined again.

[0046] The step of validating the material moisture content based on the dielectric material constant measured by the second microwave sensor is carried out by the control and evaluation device.

[0047] The method comprises the following step: drying the material, between the step of determining the material moisture content of the material and the online measurement of the dielectric material constant of the material by means of the second microwave sensor.

[0048] In an embodiment, the method and / or the device may provide that the dielectric material constants are permeability and / or permittivity.

[0049] In the design of the device, it can be provided that the dielectric material constants are permeability and / or permittivity.

[0050] Furthermore, according to the invention, a drying method comprising at least one drying device for drying a material is provided, wherein the drying method comprises a method as described above for determining the material moisture content, wherein the drying device is controlled or regulated on the basis of the determined material moisture content of the material.

[0051] In addition, according to the invention, a drying device for drying a material is provided, wherein the drying device comprises a device for determining the material moisture content of material, a device as described above, wherein the drying device is designed to be controlled or regulated on the basis of the determined material moisture content of the material.

[0052] According to the invention, the drying parameters can be controlled or regulated within the drying process or within the drying device, creating a fully automated drying process with validation. This makes it possible to save both time and costs, as the drying process can be fully automated.

[0053] For this purpose, drying parameters such as power, energy and throughput speed are set in a conveyor belt-like arrangement.

[0054] The invention will be explained below using exemplary embodiments with reference to the drawings.

[0055] It shows: Fig. 1 is a schematic representation of a device for determining the material moisture content according to an embodiment of the invention; Fig. 2 is a schematic representation of a method as a flow chart for determining the material moisture content according to the embodiment of Fig. 1 ; Fig. 3 a schematic representation of a device for determining the material moisture Fig. 4 a schematic representation of a method as a flow chart for determining the material moisture according to the embodiment according to Fig. 3 ; Fig. 5 shows a schematic representation of a microwave measuring unit; Fig. 6 shows a schematic representation of a resonant microwave sensor; and Fig. 7 shows a schematic representation of a transmitting microwave sensor.

[0056] Fig. 1 shows an embodiment of a device 1 according to the invention for determining the material moisture content of bulk material or solid bodies K, in particular of pyrotechnic and / or explosive substances. The device 1 comprises a referencing device 5, which is used to reference a material by determining the material moisture content of a material sample P of the material K as a function of the mass of the material sample P. According to this embodiment, the referencing device is a drying-weighing device with which the material moisture content of the material sample P can be determined as a function of its mass. The referencing device 5 is arranged offline.

[0057] In addition, the device 1 has a microwave measuring device 15 for determining the dielectric material constant D sample of the material sample P as a function of the material moisture content. The microwave measuring device 15 is designed to determine the dielectric material constant D sample of the material sample P as a function of the material moisture content based on the material moisture content previously determined by the referencing device 5. The structure of the microwave measuring device 15 is shown in Fig. 5 and will be subsequently Fig. 5 described.

[0058] The device 1 further comprises a control and evaluation device 20. The control and evaluation device 20 is operatively connected to the referencing device 5 and to the microwave measuring device 15. The data obtained by the referencing device 5 are transmitted to the control and evaluation device 20 and can be stored there. For this purpose, the control and evaluation device 20 has at least one memory. Likewise, the data obtained by the microwave measuring device 15 are transmitted to the control and evaluation device 20 and can be stored there.

[0059] The device comprises a first online microwave sensor 10. This is designed to measure the dielectric material constant D mess1 of the material K. This is arranged on a production line 3 of the material K, along which the material K is transported. The microwave sensor 10 is operatively connected to the control and evaluation device 20, and the control and evaluation device 20 is configured to calibrate the first microwave sensor 10 based on the dielectric material constant of the material sample P determined by the microwave measuring device 15.

[0060] The control and evaluation device 20 is further configured to determine the material moisture content of the material K based on the dielectric material constant D mess1 previously measured online by the first microwave sensor 10.

[0061] The device 1 further comprises a second online microwave sensor 30. This is designed to measure the dielectric material constant D mess2 of the material K. It is arranged on a production line 3 of the material K, along which the bulk material or the solid body K is transported. The second microwave sensor 30 is operatively connected to the control and evaluation device 20, and the control and evaluation device 30 is configured to calibrate the second microwave sensor 30 based on the dielectric material constant of the material sample P measured by the microwave measuring device 15.

[0062] The control and evaluation device 20 is further configured to determine the material moisture content of the material K based on the dielectric material constant D mess2 previously measured online by the second microwave sensor 30.

[0063] Furthermore, the control and evaluation device 20 is configured to validate the material moisture content based on the dielectric material constant D mess2 measured by the second microwave sensor 30. For this purpose, the material moisture content determined by the first microwave sensor 10 and the material moisture content determined by the second microwave sensor 30 are compared.

[0064] Fig. 2 shows a schematic representation of a method for determining the material moisture according to the embodiment according to Fig. 1 The method according to the invention serves to determine the material moisture content of the material K and comprises the following steps.

[0065] First, in a first step S10, the material K is referenced using the referencing device 5. This is done by determining the material moisture content of the material sample P of the material K as a function of the mass of the material sample P.

[0066] Subsequently, in a further step S20, the dielectric material constant D sample of the material sample P is determined S20 as a function of the material moisture content. This is done by the microwave measuring device 15.

[0067] Subsequently, in the next step S30, the first microwave sensor 10 is calibrated using the dielectric material constant D sample of the material sample P.

[0068] Thereafter, in the next step S40, an online measurement of the dielectric material constant D mess1 of the material K is carried out by means of the first microwave sensor 1.

[0069] Finally, in step S50, the material moisture content of the material K is determined based on the previously online measured dielectric material constant D mess1 S50.

[0070] This is done by the control and evaluation device 20.

[0071] As already stated above, the referencing device is arranged offline, so that the step of referencing the material with a referencing device (5) takes place offline. Fig. 3 shows a further embodiment of the device 1, which is based on the device according to Fig. 1 and additionally has a second microwave sensor 30. Optionally, a microwave drying device 40 is configured for drying the material K, which is preferably arranged online between the first microwave sensor 10 and the second microwave sensor 30.

[0072] The second microwave sensor 30 measures the dielectric material constants D Mess2 of the material K online and is preferably arranged in a line behind the first microwave sensor. The control and evaluation device 20 then determines the material moisture content of the material K based on the measured dielectric material constants D Mess1 , D Mess2 .

[0073] Based on this dielectric material constant D Mess2 obtained by the second microwave sensor 30, the material moisture content of the material K is again determined.

[0074] Based on the two measured material moisture values, the moisture content of material K is validated. The control and evaluation device 20 is configured to perform such a validation. For this purpose, it compares the first and second online measured dielectric material constants D Mess1 and D Mess2. This compares the first and second determined material moisture values.

[0075] Fig. 4 a schematic representation of a process flow for determining the material moisture according to the embodiment according to Fig. 3 The procedure is based on the procedure described in Fig. 2 The steps S10 to S50 of the method according to Fig. 4 correspond to the steps of the procedure according to Fig. 2 .

[0076] The method comprises, after step S50, as a subsequent step S70, an online measurement of the dielectric material constant D mess2 of the material K by means of the second microwave sensor 30.

[0077] Subsequently, in the next step S80, the material moisture content of the material (K) is determined again based on the previously measured online dielectric material constant D mess2. Furthermore, the method comprises, in the subsequent step S90, validating the material moisture content based on the dielectric material constant D mess2 measured by the second microwave sensor 30.

[0078] Between steps S50 and S70, a step S60 is carried out in which drying of the material K is carried out by means of the second microwave sensor 30.

[0079] Fig. 5 shows a schematic representation of a microwave measuring unit 15, which is designed as a vector network analyzer. Such vector network analyzers are manufactured by various manufacturers and can be purchased from them.

[0080] Fig. 6 shows a schematic representation of a resonant microwave sensor 10, which is designed as a resonant 1-port sensor. This sensor measures both the electromagnetic waves radiated into the material and the waves reflected by the material. The measured reflection factor is a measure of the dielectric properties of the material M. A resonant 1-port sensor allows penetration depths of up to 30 cm to be achieved, and moisture measurements within the material volume are possible.

[0081] Fig. 7 shows a schematic representation of the first and second microwave sensors 10', 30', each of which is designed as a transmitting microwave sensor 10', 30', in particular as a transmitting 2-port sensor. Such a transmitting microwave sensor 10', 30' has both a microwave transmitter 11, 31 and a microwave receiver 12, 32, which are installed, for example, above and below a conveyor line for the material M.

[0082] This allows the material moisture content of a continuous material flow of material M to be checked as described above.

[0083] In addition, such a system can have an optional sensor for distance compensation. BEZUGSZEICHENLISTE

[0084] 1Device 3Production line 5Reference device 10First microwave sensor 15Microwave measuring device 20Control and evaluation device 30Second microwave sensor 40Microwave drying device D sample dielectric material constants of the sample D mess2 dielectric material constants measured by the first microwave sensor D mess2 dielectric material constants measured by the second microwave sensor Kbulk material or solid Pmaterial sample

Claims

1. Method for determining the material moisture of a pyrotechnic and / or explosive substance (K), comprising the following steps: referencing the pyrotechnic and / or explosive substance using a referencing device (5) by determining the material moisture of a material sample (P) of the pyrotechnic and / or explosive substance (K) on the basis of the mass of the material sample (P) (S10); determining the dielectric material constants (DProbe) of the material sample (P) on the basis of the material moisture (S20); calibrating a first microwave sensor (10) on the basis of the dielectric material constants (DProbe) of the material sample (P) (S30); online measurement of the dielectric material constants (Dmess1) of the pyrotechnic and / or explosive substance (K) by means of the first microwave sensor (10) (S40); determining the material moisture of the pyrotechnic and / or explosive substance (K) on the basis of the dielectric material constants (Dmess1) previously measured online (S50); drying the pyrotechnic and / or explosive substance (K) by means of a second microwave sensor (30) (S60); and online measurement of the dielectric material constants (Dmess2) of the substance (K) by means of the second microwave sensor (30) (S70); redetermining the material moisture of the pyrotechnic and / or explosive substance (K) on the basis of the dielectric material constants (Dmess2) previously measured online by means of the second microwave sensor (S80).

2. Method according to claim 1, characterized in that the method further comprises the following step: validating the material moisture on the basis of the dielectric material constants (Dmess2) measured by the second microwave sensor (30) (S90).

3. Method according to any of the preceding claims, characterized in that the following step is carried out between the step of determining the material moisture of the material (K) (S50) and the online measurement of the dielectric material constants (Dmess2) of the material (K) by means of the second microwave sensor (30) (S70): drying the material (K) (S60).

4. Method according to any of the preceding claims, characterized in that the dielectric material constants (DProbe, Dmess1, Dmess2) are permeability and / or permittivity.

5. Method according to any of the preceding claims, characterized in that the step of referencing the pyrotechnic and / or explosive substance (K) using a referencing device (5) takes place offline.

6. Drying method comprising a method for determining the material moisture according to any of claims 1 to 5, wherein a drying apparatus is controlled or regulated on the basis of the determined material moisture of the pyrotechnic and / or explosive substance (K).

7. Device (1) for determining the material moisture of a pyrotechnic and / or explosive substance (K), comprising - a production line (3) along which the pyrotechnic and / or explosive substance (K) is transported; - a referencing device (5) for referencing a material by determining the material moisture of a material sample (P) of the pyrotechnic and / or explosive substance (K) on the basis of the mass of the material sample (P); - a microwave measuring apparatus (15) for determining the dielectric material constants (DProbe) of the material sample (P) on the basis of the material moisture; - a control and evaluation apparatus (20) which is designed to calibrate a first microwave sensor (10) on the basis of the dielectric material constants of the material sample (P); and - the first microwave sensor (10), which is arranged online, for measuring the dielectric material constants (Dmess1) of the pyrotechnic and / or explosive substance (K), wherein the control and evaluation apparatus (20) is further designed to determine the material moisture of the pyrotechnic and / or explosive substance (K) on the basis of the dielectric material constants (Dmess1) previously measured online, wherein the device comprises a second microwave sensor (30) for drying the pyrotechnic and / or explosive substance (K), wherein the control and evaluation apparatus (20) is further designed to carry out online measurement of the dielectric material constants (Dmess2) of the substance (K) by means of the second microwave sensor (30) (S70), and the control and evaluation apparatus (20) is designed to determine the material moisture of the pyrotechnic and / or explosive substance (K) on the basis of the dielectric material constants (Dmess2) previously measured online by means of the second microwave sensor (30) (S80).

8. Device (1) according to claim 7, characterized in that the control and evaluation apparatus (20) is designed to validate the material moisture by means of the second microwave sensor (30), which is arranged online.

9. Device (1) according to any of claims 7 or 8, characterized in that the dielectric material constants are permeability and / or permittivity.

10. Device (1) according to any of claims 7 to 9, characterized in that the referencing device (5) for referencing the pyrotechnic and / or explosive substance (K) is arranged offline.

11. Drying device for drying a pyrotechnic and / or explosive substance (K), characterized in that the drying device comprises a device (1) for determining the material moisture of the pyrotechnic and / or explosive substance (K) according to any of claims 7 to 10, the drying apparatus being designed to be controlled or regulated on the basis of the determined material moisture of the pyrotechnic and / or explosive substance (K).