Method for detecting a mold center

Abstract

The invention relates to a method for detecting a mold center in a bale of organic material, wherein a spatially resolved temperature measurement is carried out with at least one temperature sensor and additionally a measurement of a moisture profile of the bale is carried out by a microwave transmission measurement, wherein the detection of mold centers is carried out by a joint evaluation of the temperature measurement and the microwave transmission measurement.

Description

The present invention describes a method for detecting a mold center in a bale consisting of organic material. Such mold centers are sometimes referred to as hot spots in technical terms, wherein a hot spot can also refer to an area which carries the risk of becoming a mold center. There are a number of agricultural products such as tobacco, hop, alfalfa, hay, straw, cotton or silage which are stored and / or transported in bale form. Since these are biological or natural materials, it must be assumed that these have fluctuations with regard to their physical properties. These variations can promote mold formation in the bale or promote other biological processes, for example, in the case of unfavourable variations in moisture and density. In these zones, an increased temperature can thereby be produced. In this case, auto-ignition of the bale material can even occur.EP 2 179 273 B1 discloses a microwave transmission measurement of bale-shaped objects, in which a simultaneous measurement of moisture and density of the bale is possible. The temperature of the bale is also measured to correct the moisture and density readings for temperature variations.U.S. Pat. No. 6,107,809 describes a microwave transmission measurement for moisture and density measurement of tobacco. In this method too, the measurement of the product temperature serves to correct the measured values of moisture and density with respect to the influence of temperature fluctuations. The detection of density variations is used here for detecting foreign bodies.The object of the invention is to provide a method with which mold formation in bales can be detected reliably.According to the invention, the object is achieved by the method having the features of claim 1. Advantageous embodiments form the subject matter of the dependent claims.The method according to the invention is designed to detect a mold center inside a bale of organic material. The method works with a spatially resolved temperature measurement, a temperature sensor and additionally with a measurement of a moisture profile of the bale by a microwave transmission measurement. For detecting the mold center, a joint evaluation of the temperature measurement and the microwave transmission measurement takes place. In the method according to the invention, a measurement is provided simultaneously with the measurement of moisture profiles for the spatially resolved temperature measurement, which measurement also allows conclusions to be drawn about hot spots or mold centers already formed in the interior of the bale. The particular aspect of this invention is that the spatially resolved temperature measurement records the surface temperature of the bale, while the moisture profile describes the moisture values along a measurement direction through the interior of the bale. In the method according to the invention, surface values for the temperature are thus combined with a moisture profile from the interior of the bale.In a preferred development, a density profile of the bale is additionally measured by the microwave transmission measurement. The density measurement of the bale is likewise carried out as a measurement of a density profile in the interior of the bale, wherein the moisture profile and the sealing profile preferably run parallel to one another in their profile direction.In a further preferred embodiment, the joint evaluation takes place with regard to local deviations of the measured temperature, the measured moisture content and / or in the measured density of the bale from its average value. In this method step, an average value is calculated for a variable such as temperature, moisture content and / or density. Preferably, the average value for a measured profile can be determined as the average value along the profile. The local values are evaluated with respect to their difference from the average value and thus local deviations can be detected. For example, a local deviation may be assumed for the joint evaluation if the corresponding measured variable deviates from the average value by a predetermined threshold value. It is also possible to record the variance or the standard deviation of the values and to assume a critical local deviation if the measured values deviate from the average value by more than the standard deviation or a multiple of the standard deviation.In a preferred embodiment, the detection of the mold center takes place by a level of the temperature increased compared to the average value or by a moisture content increased compared to the average moisture with simultaneous local deviation of the other measured values from their average values in the bale. In this embodiment, therefore, for example, an increased temperature level and an increased moisture content are present. In addition, the positions in the bale at which the elevated values occur correspond.Various sensors can be used for the temperature measurement. An infrared sensor can preferably be used. It is also possible to use fiber-optic sensors for temperature measurement. At least one thermal imaging camera can also be used for temperature measurement. With regard to microwave transmission measurement, two different arrangements for the antenna can be distinguished. In one arrangement, the antennas are placed on opposite sides of the bale. The transmission measurement is carried out in this case on the direct path between the antennas. Alternatively, for the microwave transmission measurement it can be provided that the two antennas are placed on the same side of the bale. In this case, the wave package running back and forth in the bale is measured during transmission. With this arrangement of the antennas, the precision of the measurement can be improved by using a reflector arranged on the side of the bale opposite the antennas.Preferred embodiments of the invention will be described below. The following are shown: FIG. 1 shows a microwave transmission measuring device, antennas and temperature measuring devices facing each other, FIG. 2 shows a microwave transmission device with antennas and temperature measuring devices arranged side by side, FIGS. 3 a,b Moisture content, temperature and density along the direction of movement for (a) a bale without a mold center and (b) a bale with a mold center, FIG. 4 shows a microwave transmission device without antennas, with a portal-like arrangement of temperature measuring devices, and FIG. 5 shows the temperature profile for the individual sensors during transport of the bale through the temperature measuring devices.FIG. 1 shows an arrangement of temperature sensors 6 which are arranged behind two antennas 4, 5 for microwave transmission measurement in the direction of movement. Antennas 4 and 5 are designed as transmitting antenna 4 and receiving antenna 5. The bale 1 of organic material is moved through between the antennas 4 and 5 via a conveyor belt 2. The transmitting antenna 4 emits microwave radiation which is received by the receiving antenna 5. Due to the dielectric properties of the organic material in the bale 1 and the moisture contained therein, conclusions can be drawn with the microwave transmission measurement about a density and a moisture profile in the bale.During the movement of the bale 1 in the direction of 3, approximately the center of the bale between the antennas 4, 5 is illuminated and density and moisture profiles are created. As the bale continues to move, it is likewise guided by the temperature sensors 6. Since the speed of movement 3 of the bale 1 is known, the temperature signals of the temperature sensors 6 along the longitudinal axis of the bale can be assigned to the moisture and density profiles.FIG. 2 corresponds to the arrangement of FIG. 1, with the decisive difference that transmitting and receiving antennas 4 are arranged on the same side of the bale. This means that the microwave radiation passes twice through the bale. In this measurement as well, with transmitting and receiving antenna on one side, profiles can be created along the bale in the direction of movement, the individual measurement points of which represent the mean values of moisture or density in the direction of transmission on the forward and return path. With this arrangement of the antennas, the precision of the measurement can be improved by using a reflector arranged on the side of the bale opposite the antennas.FIGS. 3 aand 3 b show the recorded measured values for the moisture content, for the temperature recorded with infrared sensors and the density measured with microwaves in the longitudinal direction of the bale, i.e. in the transport direction 3 of the bale. The scale for moisture content in percent and density and temperature in degrees Celsius is plotted on the left ordinate and for the density on the right ordinate.FIGS. 3 aand 3 b show the measurement along the movement direction 3 of the bale for the density and the moisture content as well as the temperature at the bale surface recorded by an infrared sensor. For understanding, it is helpful to envisage that the moisture content and the density are recorded along a straight line in the Y-Z plane and then assigned as an average value to the corresponding X value of the Y-Z plane. The straight line in the Y-Z plane at the location X surrounds a measurement field which is extended in the X-Y direction. FIG. 3a shows a substantially non-significant curve with an approximately constant temperature, a slight ripple in the moisture content and a density of the bale which increases slightly in the X direction. This behavior is in total not noticeable and still gives no reason to assume mold formation or a hot spot.The situation in FIG. 3 b looks somewhat different. Here, for X=20 cm, a distinct maximum in density and temperature is evident. The moisture level, too, has an increased level overall in the range of 0-30 cm, even if a local minimum is present in the range between 15 and 20 cm. This indicates that there is a region with an elevated temperature in the bale, in which region either mold has already formed or there is an increased risk of mold formation.FIG. 4 shows, for a better overview, the distribution of six temperature sensors 6.1-6.6 for temperature detection on the bale 1, which is moved in the direction of movement 3 through the portal with the temperature sensors.In FIG. 5, the temperature curves recorded by the sensors can be seen, wherein the X axis indicates the positions in the direction of movement 3 in centimeters. It can clearly be seen that the sensor 6.2 detects a pronounced maximum at approximately 20 cm with an absolute value of more than 22° C. The adjacent sensors 6.1 and 6.3 are also influenced by the locally elevated temperature. The effects of the elevated temperature can still be clearly recognized even with the sensors 6.4 and 6.5.A hot spot or a mold center can be identified here as follows:detecting the highest temperature value in all profiles and comparing it with a defined threshold value,detecting the fluctuation of the measured values of the individual profiles, absolute fluctuation or relative deviation, based on the mean values. Comparison of the Largest Detected Variation with a Defined Threshold Value.calculating the mean values of the temperatures of the individual profiles. Comparison of the largest detected mean value with a defined threshold value (absolute or based on standard deviation).With the temperature profiles shown in FIG. 5, a rough localization of the hotspot in the bale can also be achieved. In the example shown, the hotspot in the upper part of the bale is to be expected to be closer to the sensor 6.2 than the sensor 6.5 at a length in the transport direction of 20 cm. By comparing the signals with the sensors 6.3 and 6.4, an indication is also given as to the lateral orientation that the hot spot is located closer to the sensor 6.3 than to 6.4.For the detection of mold centers in bales of biological products, there is a wide field of technical application, for example for agricultural products which are brought into bale form after harvesting or during the harvesting process. For a large number of materials, such as hay, straw and cotton, this is done in order to be able to transport and store the material better. The bale geometry also allows stacking of the material and thus allows space-saving storage. Furthermore, certain materials are also compressed into bales in which intended chemical processes proceed, such as, for example, ripening or fermentation. Such materials are, for example, tobacco and silage, for example with grass or maize.Also, tobacco leaves are not immediately processed into consumable end products after harvesting, but are subjected to a maturation and fermentation process to develop the desired taste, aroma and quality. This maturation phase can last several months to several years. During this time, the tobacco leaves are often compressed into bales to aid the fermentation process. While the fermentation process is desirable for tobacco and contributes to the development of the typical taste and aroma, undesirable chemical processes due to microbiological activity can also occur during the storage of the tobacco.Fermentation of silagen is an anaerobic process. Here, lactic acid bacteria produce preservatives which prevent the growth of harmful microorganisms.The formation of mold can be promoted on the one hand by the storage conditions of the bales: the higher the storage temperature and the longer the storage time, the greater the probability of mold formation. The formation of mold can also be promoted by the structure of the bales: oxygen and water are necessary for mold formation. Areas of the bale with high moisture content are therefore favored centers for mold formation. Areas of high density and high moisture can occur in bales, which support mold formation. In this region, the air circulation is restricted and evaporation of the moisture is prevented.In silage bales, for example, mould formation preferably takes place in regions of low density. The anaerobic fermentation process requires a high material density, with the greatest possible air separation. In addition, silage bales are surrounded airtight by foil.There is normally an elevated temperature in the centers of mold above the average temperature of the intact bales. The elevated temperature is produced by the metabolism of the mold. This property basically allows the possibility of determining hot spots by a spatially resolved temperature measurement. The reliability of the detection is increased if a further profile measurement from a microwave transmission measurement is additionally added.The spatially resolved temperature measurement can be effected by the arrangement of one or more infrared temperature sensors, as illustrated for example in FIG. 4. When using infrared temperature sensors, it is important to calibrate the sensors properly. It should also be noted that erroneous measurements may occur due to dust or effects on the bale surface (for example, varying structure or color). A solution for temperature measurement that is insensitive to disturbances is the fiber-optic sensors. A further very advantageous possibility consists in the use of one or more thermal imaging cameras, in which a spatially resolved thermal image of the bale is generated by the infrared radiation emitted by the bale. In the microwave transmission measurement, the measuring system is mounted on the conveyor belt 2 in a predetermined position for the spatially resolved measurement, so that the bales on the conveyor belt move through the respective measurement fields of the antennas. Alternatively, it is also possible to mount the microwave measuring system on a displaceable or movable holder and to move it over the bale in its longitudinal direction.The microwave measurement system measures the phase shift and attenuation of the microwave signal as it travels through the bale. From these measured values, the moisture content and the density of the bale can be calculated, wherein in both cases a profile measurement is also possible.It is to be expected that a hot spot in a bale has a temperature maximum and at the same time a maximum of the moisture content is present. In addition, an extreme of the density values usually occurs. Not only is a detection of local extremes of the measured values relevant during the evaluation, but the overall level of the parameters must also be taken into account. Thus, at a high total temperature of a bale, the creation of a hot spot and the formation of mold is more likely than at one with a lower total temperature. The probability then increases particularly at locations with an increased moisture content and / or extreme of the density value.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 2 179 273 B1

[0002] U.S. Pat. No. 6,107,809 A

[0003]

Claims

Method for detecting a mould centre in a bale of organic material, characterized in that a spatially resolved temperature measurement is carried out with at least one temperature sensor and additionally a measurement of a moisture profile of the bale is carried out by a microwave transmission measurement, wherein a joint evaluation of the temperature measurement and the microwave transmission measurement is carried out for detecting mould centres.Method according to claim 1, characterized in that a measurement of a density profile of the bale is additionally carried out by the microwave transmission measurement.Method according to claim 1 or 2, characterised in that the joint evaluation takes place local deviations of the measured temperature, the measured moisture content and / or the measured density of the bale from its average values.Method according to claim 3, characterised in that the detection of the mould centre takes place by a level of the temperature increased with respect to the average value or by a moisture content increased with respect to the average moisture and simultaneous local deviations of the other measured values from the average measured values of the bale.Method according to one of Claims 1 to 4, characterized in that the temperature measurement is carried out by at least one infrared sensor.Method according to one of Claims 1 to 4, characterized in that the temperature measurement is carried out by at least one fibre-optic sensor.Method according to one of Claims 1 to 4, characterized in that the temperature measurement is carried out by at least one thermal imaging camera.Method according to any one of claims 1 to 7, characterised in that the microwave transmission measurement is made by two antennas placed on opposite sides of the bale.Method according to any one of claims 1 to 7, characterised in that the microwave transmission measurement is carried out by two antennas placed on the same side of the bale.

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