Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more
  • G01N22/04—Investigating moisture content

Definitions

• the invention relates to a method for continuously detecting the moisture of a bulk material in online operation, in particular for food or feed components, a microwave field being generated and the temperature of the bulk material being measured.
• the most common method is that by measuring the microwave attenuation and regardless of that
• Density of the moist sample is determined.
• the big disadvantage is that two completely different measuring methods have to be used.
• the Microwave attenuation and on the other hand for example Gamma rays or a weighing system for density. It follows (as far as the applicant is aware) that very special measuring devices had to be developed for the practice of poorly flowable goods such as freshly wetted wheat.
• CH-PS No. 650 862 proposes a density-independent microwave measurement. It is envisaged to carry out the measurement in four steps, the mechanical and electrical properties of the microwave applicator being measured first without the measurement material and the second step with the measurement material. Doing so. z.
• the complex dielectric constant is calculated with the attenuation and phase measurement of the microwave reflection and transmission. A measured value is determined according to the predetermined formula, this is compared with a calibration curve and the relative humidity is determined therefrom.
• the disadvantage of this method lies in the fact that in each case the micorwave applicator without material, approximately similar to the tarame measurement on the balance, has to be detected. It is known that even a thin coating on the walls of the microwave applicator influences the empty measurement, so that this does not match the factory-new empty value measurement.
• the object of the invention was now to largely eliminate the disadvantages of the known readings, but in particular * to allow a microwave measurement which is simple to use in practice and does not require a bulk density measurement or a respective microwave measurement without a product .
• the solution according to the invention is characterized in that the amount and the phase of the transmitted microwaves in the bulk material are measured, the moisture is calculated therefrom and the moisture of the bulk material is regulated with the calculated value.
• the large dispersions found so far have often been caused by the fact that extreme cases that are rare in practice always had to be taken into account when searching for suitable laws.
• the fact is that the grain may be wetted three times in a mill, one main wetting and two post-wetting.
• wetting is not regulated on the basis of moisture measurement values, but is based on experience, for example. 0.1, 0.2 or 0.3% water added. The actual regulation of the addition of water takes place only once, with the main wetting. In this case, a value of e.g. 14.5 - 17% water content of the moistened grain are maintained.
• the entire measuring method now measures water addition of less than 6%, that is to say only a small percentage of water, for example. less than 3% of dry wheat, can mainly be used.
• the bulk density measurement can be dispensed with as a great advantage, because preferably due to the slight congestion, a certain constancy with respect to the bulk density is required.
• the invention allows a whole series of further advantages, for example the water content during the wetting and / or drying of food or feed components is recorded and a corresponding treatment is preferably regulated.
• the amount and the phase of the transmitted microwaves in the treated bulk material are preferably measured. Another new aspect is that the temperature of the untreated goods is measured.
• the greatest measurement accuracy is also achieved by using an antenna which penetrates the bulk material and which generates and guides the microwave field in the bulk material, the microwave field being very particularly preferably generated in a last section of the process zone within a bulk material accumulation zone.
• the bulk material is very particularly preferably brought into an intensive swirling in a first section, water is added and in a second section an even water distribution is generated by maintaining a fluidized bed and in a last section vortex-free section is formed, in which a slight traffic jam is generated and the microwave field is built up therein, and the derived or calculated water content as an actual value is compared with a target value for regulating the water addition to the crop.
• the invention further relates to a device for the continuous detection of the moisture of a bulk material in online operation, in particular for food or animal feed, and a measuring channel for the passage of the bulk material with a backflow element on the outlet side of the measuring channel and in the stowage zone within the measuring channel has a sensor with a rod transverse to the product flow direction.
• the new configuration allows a very high measurement accuracy to be obtained with little effort for the calibration due to the defined structural configuration, particularly because the invention allows constant measurement conditions to be maintained for the bulk material.
• the damming element is preferably formed by a forced conveying element. This also allows bulk goods such as flour, bran or other very moist goods to be measured that are no longer free-flowing.
• the measuring channel is designed as a by-pass, the positive feed element being designed as a return feed element in the main channel.
• the measuring channel preferably also has a cross-sectional widening in the flow direction of the bulk material.
• the rod can have a sword-shaped cross section with the longer dimension in the product flow direction.
• a particularly advantageous application of the invention is characterized in that it has a first treatment section and a section for creating a bulk material storage zone, and a microwave measuring device which is assigned to the storage zone and a control device for regulating a specific bulk material water content in the Treatment section.
• FIG. 1 shows the schematic structure of the microwave measuring part
• FIG. 2 shows an overall arrangement of a grain network device
• FIG. 3 shows a further advantageous embodiment for detecting the water content of bulk material
• a measuring section 1 is formed by a funnel 2 widened downwards, with an inlet in the upper part sliding valve 3 and in the outlet area a bottom valve 4 is arranged.
• a funnel-shaped antenna 5, which is connected by a rod 6 to an opposite receiving antenna 7, is arranged on the side of the funnel in the left half of the figure.
• the rod 6 completely penetrates the bulk material located in the funnel 2. Due to the bottom slide 4 set to a limited throughput, the funnel 2 remains constantly filled with product in the operating state. As a result, there is a slight jam in the area of the antenna 5 or the rod 6 or the receiving antenna 7.
• the antenna 5 is connected to a high-frequency generator 9 via a coaxial line 8.
• An electronic evaluation system 10 calculates the effective moisture of the bulk material from the microwave measurement values and the material temperature determined by means of a temperature probe 11. It is essential that the microwave signal transmitted from the antenna 5 is measured via a coaxial return line 12 for the calculation of the moisture value with respect to the amount and phase and processed in the evaluation electronics 10.
• the signal required for the control is passed on via a control line 13.
• the energy required for the unit is fed in via a power connection line 14.
• a bulk material depth of 5 to 30 cm is preferred for the device, a microwave frequency of 2 to 12 gigahertz being selected, the corresponding microwave transmission elements being adapted according to the relevant frequency rules. It is also important that the measured material also lies in the specified dimensions in the two other spatial directions,
• FIG. 2 shows an entire network device with the addition of water.
• the bulk material is fed into the actual network apparatus 22 via a connecting line 20 and an inlet trim 21.
• the network apparatus 22 essentially consists of a tubular network jacket 23, a rotating rotor 24, which ensures a product conveyance upwards by means of a corresponding blading 25.
• the rotor 24 is driven by an overdrive 26 and a drive motor 27.
• the network water is fed to the network apparatus 22 in a first section via a connecting line 28, the amount of water being set by a control valve 29.
• the temperature of the grain can be measured either in the first section of the network apparatus 22, before the addition of the network water, and / or in the last section of the network apparatus 22, on the fully moistened bulk material.
• the temperature value or values are transferred to a computer 30 which carries out the essential information processing for the networking.
• the bulk material passes through the upper opening 102 into the measuring section 101 and is deflected by a storage zone 103 and is directed into the main duct 104 which is bent to the left.
• the storage zone 103 is laterally delimited by a measurement channel 105, a conveying element 107 conveying the bulk material back into the main channel via an outlet 106.
• the conveying element 107 in FIG. 3 is shown as a screw conveying element, a different type of mechanical discharge form, for example. a rotary lock can be used. What is essential in this embodiment is the condition that the conveying element has a lower discharge rate than the smallest possible amount through the opening - 11 -
• the conveying element 107 is controlled by a controllable drive motor 108 by an electronics unit 109.
• the temperature of the bulk material is measured with a probe 110 and transmitted to the electronics unit 109 for recycling. This is particularly true in the case of a pure water content measurement.
• the temperature before the addition of water is preferably recorded exactly.
• a regulation e.g. the water can be added or dried via a control line 111.
• the rod 112 in the exemplary embodiment is designed in cross section in the form of a sword.
• the sword shape causes the smallest possible disturbance for the flow of bulk material, sufficient robustness for the mechanical stress and results in correct measured values.
• the conveying element 107 preferably has a progressive screw pitch, respectively. a correspondingly tapering screw core.
• the measuring channel 105 is extended downwards, as shown in FIG. It is advisable to choose the discharge area of the conveying element approximately as large as the cross-sectional area of the measuring channel 105 such that in any case the bulk material is lowered into the measuring channel in a spatially and temporally uniform manner.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
• Drying Of Solid Materials (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=4279536

Family Applications (1)

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Cited By (11)

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Citations (2)

• 1988
  • 1988-12-14 CH CH462188A patent/CH678229A5/de not_active IP Right Cessation
• 1989
  • 1989-12-12 AU AU46453/89A patent/AU4645389A/en not_active Abandoned
  • 1989-12-12 EP EP19890913160 patent/EP0400126A1/de not_active Withdrawn
  • 1989-12-12 WO PCT/CH1989/000217 patent/WO1990007110A1/de not_active Application Discontinuation

Patent Citations (2)

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