Method for detecting a mold center

Abstract

Method for detecting a mold center in a bale (1) of organic material, characterized in that a spatially resolved temperature measurement is carried out with at least one temperature sensor (6) and additionally a measurement of a moisture profile of the bale (1) 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 the detection of mold centers.

Description

[0001] The present invention describes a method for detecting a mold center in a bale made of organic material. Such mold centers are sometimes referred to as hot spots, and a hot spot can also denote an area that is at risk of becoming a mold center. A number of agricultural products, such as tobacco, hops, alfalfa, hay, straw, cotton, or silage, are stored and / or transported in bales. Since these are biological or natural materials, it must be assumed that their physical properties are subject to fluctuations. These fluctuations can, for example, promote mold growth in the bale due to unfavorable variations in moisture and density, or encourage other biological processes. This can lead to elevated temperatures in these areas.This can even lead to spontaneous combustion of the bale material.

[0002] From EP 2 179 273 B1 and DE 10 2007 057 092 A1, a microwave transmission measurement method for bale-shaped objects is known, which allows for the simultaneous measurement of the bale's moisture and density. The bale's temperature is also measured to correct the moisture and density readings for temperature fluctuations.

[0003] US Patent 6,107,809 A describes a microwave transmission measurement method for determining the moisture and density of tobacco. In this method, measuring the product temperature is also used to correct the moisture and density measurements for the influence of temperature fluctuations. The detection of density variations is used to identify foreign matter.

[0004] The invention is based on the objective of providing a method with which mold formation in bales can be reliably detected.

[0005] According to the invention, the problem is solved by the method with the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

[0006] The method according to the invention is designed to detect a mold center inside a bale of organic material. The method uses spatially resolved temperature measurement, a temperature sensor, and additionally, a microwave transmission measurement to determine the moisture profile of the bale. To detect the mold center, the temperature and microwave transmission measurements are evaluated together. In the method according to the invention, the spatially resolved temperature measurement and the measurement of moisture profiles are performed simultaneously, allowing conclusions to be drawn about hot spots or mold centers that have already formed inside the bale. The special aspect of this invention lies in the fact 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 inventive method, surface temperature values ​​are combined with a moisture profile from the interior of the bale.

[0007] In a preferred embodiment, the density profile of the bale is additionally measured using microwave transmission measurement. The density measurement of the bale is also performed as a measurement of a density profile within the bale, wherein the moisture profile and the density profile preferably run parallel to each other in their profile direction.

[0008] In a further preferred embodiment, the combined evaluation focuses on local deviations of the measured temperature, moisture content, and / or density of the bale from its average value. In this process step, an average value is calculated for a parameter 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, thus enabling the detection of local deviations. For example, a local deviation can be assumed for the combined evaluation if the corresponding measured parameter deviates from the average value by a predetermined threshold. It is also possible to calculate the variance or...to record 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.

[0009] In a preferred embodiment, the mold center is detected by an elevated temperature level or a higher moisture content than average, combined with local deviations of other measured values ​​from their averages within the bale. In this embodiment, for example, both an elevated temperature level and an elevated moisture content are present. Furthermore, the positions within the bale where the elevated values ​​occur are identical.

[0010] Various sensors can be used for temperature measurement. An infrared sensor is preferred. Fiber optic sensors can also be used for temperature measurement. At least one thermal imaging camera can also be used for temperature measurement. Regarding microwave transmission measurement, two different antenna configurations can be distinguished. In one configuration, the antennas are placed on opposite sides of the bale. The transmission measurement is then taken along the direct path between the antennas. Alternatively, for microwave transmission measurement, both antennas can be placed on the same side of the bale. In this case, the wave packet traveling back and forth within the bale is measured during transmission.With this antenna arrangement, the precision of the measurement can be improved by using a reflector positioned on the side of the bale opposite the antennas.

[0011] Preferred embodiments of the invention are described below. They show: Fig. 1 a microwave transmission measuring device, opposing antennas and temperature measuring devices, Fig. 2 a microwave transmission device with adjacent antennas and temperature measuring devices, Fig. 3a,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 A microwave transmission device without antennas is shown with a portal-like arrangement of temperature measuring devices and Fig. 5 The temperature profile for the individual sensors during transport of the bale through the temperature measuring devices.

[0012] Fig. Figure 1 shows an arrangement of temperature sensors 6, which are positioned behind two antennas 4 and 5 for microwave transmission measurement in the direction of movement. The antennas 4 and 5 are configured as a transmitting antenna 4 and a receiving antenna 5, respectively. The bale 1 of organic material is moved 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. Based on the dielectric properties of the organic material in the bale 1 and its moisture content, the microwave transmission measurement allows conclusions to be drawn about the density and moisture profile within the bale.

[0013] As bale 1 moves in the direction of 3, approximately the center of the bale between antennas 4 and 5 is scanned, and density and moisture profiles are created. During further movement of the bale, it is also guided by the temperature sensors 6. Since the speed 3 of bale 1 is known, the temperature signals from the temperature sensors 6 along the longitudinal axis of the bale can be correlated with the moisture and density profiles.

[0014] Fig. 2 corresponds to the arrangement from Fig. 1, with the crucial difference that the transmitting and receiving antennas 4, 5 are arranged on the same side of the bale 1. This means that the microwave radiation passes through the bale 1 twice. Even with this measurement, with the transmitting and receiving antennas 4, 5 on the same side, three profiles can be created along the bale 1 in the direction of movement, the individual measurement points of which each represent the mean values ​​of moisture or density in the direction of transmission on the outbound and return paths. With this arrangement of the antennas 4, 5, the precision of the measurement can be improved by using a reflector (not shown) arranged on the side of the bale 1 opposite the antennas.

[0015] The Fig. 3a and Fig. Figure 3b shows, in the longitudinal direction of the bale (i.e., in the transport direction 3 of the bale), the recorded measurements for moisture content, temperature (recorded with infrared sensors), and density (measured with microwaves). The scale for moisture content in percent and density and temperature in degrees Celsius is plotted on the left ordinate, while the scale for density is plotted on the right ordinate.

[0016] Fig. 3a and Fig. Figure 3b shows the measurements along the bale's direction of movement (3) for density and moisture content, as well as the temperature recorded on the bale's surface using an infrared sensor. To understand this, it is helpful to visualize the moisture content and density being recorded along a straight line in the YZ plane and then averaged to the corresponding X-value in the YZ plane. The straight line in the YZ plane at point X encloses a measurement field that extends in the XY direction. Fig. 3a shows a largely unremarkable progression with an almost constant temperature, slight fluctuations in moisture content, and a slight increase in bale density in the X direction. This behavior is generally unremarkable and does not yet give any reason to assume mold growth or a hot spot.

[0017] The situation is somewhat different in Fig. 3b. Here, a clear maximum in density and temperature can be observed at X = 20 cm. The moisture level is also generally elevated in the range from 0-30 cm, even though there is a local minimum between 15 and 20 cm. This indicates that there is an area with an elevated temperature within the bale where mold has either already formed or where there is an increased risk of mold growth.

[0018] Fig. Figure 4 shows, for better clarity, the distribution of six temperature sensors 6.1-6.6 for temperature measurement on the bale 1, which is moved through the portal with the temperature sensors in the direction of movement 3.

[0019] In Fig. Figure 5 shows the temperature profiles recorded by the sensors, with the x-axis indicating the positions in the direction of movement 3 in centimeters. It is clearly visible that sensor 6.2 recorded a pronounced maximum at approximately 20 cm with an absolute value exceeding 22 °C. The adjacent sensors 6.1 and 6.3 are also affected by the locally elevated temperature. The effects of the increased temperature are also clearly visible in sensors 6.4 and 6.5.

[0020] A hot spot or mold center can be identified as follows: - Detection of the highest temperature value in all profiles and comparison with a defined threshold value, - Detection of fluctuations in the measured values ​​of individual profiles, absolute fluctuation or relative deviation, relative to the mean values. Comparison of the largest detected fluctuation with a defined threshold value. - Calculation of the mean temperatures of the individual profiles. Comparison of the highest detected mean value with a defined threshold (absolute or based on standard deviation).

[0021] With the in Fig. The temperature profiles shown in the five diagrams also allow for a rough localization of the hotspot within the bale. In the example shown, the hotspot in the upper part of the bale is expected to be closer to sensor 6.2 than to sensor 6.5, assuming a length of 20 cm in the direction of transport. Comparing the signals with sensors 6.3 and 6.4 also indicates the lateral orientation, suggesting that the hotspot is located closer to sensor 6.3 than to 6.4.

[0022] There is a wide range of technical applications for detecting mold centers in bales of organic products, for example, in agricultural products that are baled after or during harvesting. This is done for a variety of materials, such as hay, straw, and cotton, to facilitate transport and storage. The bale geometry also allows the material to be stacked, thus enabling space-saving storage. Furthermore, certain materials are also baled to undergo desired chemical processes, such as ripening or fermentation. Examples of such materials are tobacco and silage, for instance, made from grass or corn.

[0023] Tobacco leaves are not immediately processed into consumable end products after harvesting, but undergo a maturation and fermentation process to develop the desired flavor, aroma, and quality. This maturation phase can last from several months to several years. During this time, the tobacco leaves are often pressed into bales to aid the fermentation process. While fermentation is desirable in tobacco and contributes to the development of its typical flavor and aroma, undesirable chemical processes can also occur during storage due to microbiological activity.

[0024] The fermentation of silage is an anaerobic process. During this process, lactic acid bacteria produce preservatives that prevent the growth of harmful microorganisms.

[0025] Mold growth can be promoted by the storage conditions of the bales: the higher the storage temperature and the longer the storage duration, the greater the likelihood of mold formation. Mold growth can also be promoted by the structure of the bales: oxygen and water are necessary for mold growth. Areas of the bale with high moisture content are therefore prime breeding grounds for mold. Areas of high density and high humidity can occur within bales, which support mold growth. In these areas, air circulation is restricted and moisture evaporation is prevented.

[0026] In silage bales, for example, mold growth occurs primarily in areas of low density. The anaerobic fermentation process requires a high material density with as little air as possible. Silage bales are also airtight, wrapped in plastic film.

[0027] The centers of mold growth typically exhibit elevated temperatures, exceeding the average temperature of intact bales. This increased temperature results from the metabolism of the mold fungus. This characteristic allows for the identification of hot spots through spatially resolved temperature measurements. The reliability of the detection is further enhanced by incorporating an additional profile measurement from a microwave transmission measurement.

[0028] Spatially resolved temperature measurement can be achieved by arranging one or more infrared temperature sensors, as for example in Fig.Figure 4 illustrates this. When using infrared temperature sensors, it is important to calibrate the sensors correctly. It should also be noted that dust or effects on the bale surface (e.g., varying structure or color) can lead to inaccurate measurements. Fiber optic sensors offer a solution for temperature measurement that is insensitive to interference. Another very advantageous option is the use of one or more thermal imaging cameras, which generate a spatially resolved thermal image of the bale using the infrared radiation emitted by the bale. For microwave transmission measurement, the measuring system is mounted at a predetermined position on the conveyor belt 2 to achieve 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 movable or movable bracket and move this over the ball in its longitudinal direction.

[0029] The microwave measuring system measures the phase shift and attenuation of the microwave signal as it travels through the bale. From these measurements, the moisture content and density of the bale can be calculated, and in both cases, a profile measurement is also possible.

[0030] It is to be expected that a hot spot in a bale will exhibit a temperature maximum and simultaneously a maximum moisture content. In addition, an extremum in density values ​​is regularly present. When evaluating the data, not only the detection of local extrema in the measured values ​​is relevant, but also the overall level of the parameters must be considered. Thus, the formation of a hot spot and the growth of mold are more likely in bales with a high overall temperature than in bales with a lower overall temperature. This probability increases even further in areas with elevated moisture content and / or an extremum in density value.

Claims

[1] Method for detecting a mold center in a bale (1) of organic material, characterized by , that a spatially resolved temperature measurement with at least one temperature sensor (6) and additionally a measurement of a moisture profile of the bale (1) 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 the detection of mold centers. [2] Method according to claim 1, characterized by , that in addition a measurement of a density profile of the bale (1) is carried out by microwave transmission measurement. [3] Method according to claim 1 or 2, characterized by , that the joint evaluation is carried out with regard to local deviations of the measured temperature, measured moisture content and / or measured density of the bale (1) from its average values. [4] Method according to claim 3, characterized by, that the detection of the mold center is made by an increased level of temperature compared to the average value or by an increased moisture content compared to the average moisture content and simultaneous local deviations of the other measured values ​​from the average measured values ​​of the bale (1). [5] Method according to any one of claims 1 to 4, characterized by that the temperature measurement is carried out by at least one infrared sensor. [6] Method according to any one of claims 1 to 4, characterized by that the temperature measurement is carried out by at least one fiber optic sensor. [7] Method according to any one of claims 1 to 4, characterized by that the temperature measurement is carried out using at least one thermal imaging camera. [8] Method according to any one of claims 1 to 7, characterized by, that the microwave transmission measurement is carried out by two antennas (4, 5) which are placed on opposite sides of the ball (1). [9] Method according to any one of claims 1 to 7, characterized by , that the microwave transmission measurement is carried out by two antennas (4, 5) which are placed on the same side of the bale (1).

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