EP0529050A1

EP0529050A1 - Device for determining quality criteria of a biomass

Info

Publication number: EP0529050A1
Application number: EP19920907507
Authority: EP
Inventors: Peter W. SCHÜTZ; Werner Winkler
Original assignee: TRAPPL Helmut
Current assignee: TRAPPL Helmut
Priority date: 1991-03-15
Filing date: 1992-03-16
Publication date: 1993-03-03
Also published as: WO1992016835A1

Abstract

Dispositif pour la détermination des critères de qualité d'une biomasse. Afin de pouvoir mesurer d'une manière simple une valeur moyenne de ces critères de qualité d'une qualité quelconque de biomasse, il est prévu un agencement d'électrodes, électrodes (15, 16, 22, 23) entre lesquelles est disposée la biomasse à examiner, lesdites électrodes (15, 16, 22, 23) étant branchées à une source de tension alternative (2) fournissant des signaux à fréquence variable, et reliées à un circuit d'analyse lequel présente un circuit de pondération (51, 52, 53) commandé par une commande séquentielle (1) commandant également la source de tension alternative, lequel attribue aux valeurs mesurées les valeurs déterminées experimentalement et correspondant aux critères de qualité.Device for determining the quality criteria of a biomass. In order to be able to measure in a simple manner an average value of these quality criteria of any quality of biomass, provision is made for an arrangement of electrodes, electrodes (15, 16, 22, 23) between which the biomass is placed. to be examined, said electrodes (15, 16, 22, 23) being connected to an alternating voltage source (2) supplying signals with variable frequency, and connected to an analysis circuit which has a weighting circuit (51, 52 , 53) controlled by a sequential command (1) also controlling the alternating voltage source, which assigns to the measured values the values determined experimentally and corresponding to the quality criteria.

Description

Device for determining quality criteria of a

Biomass

The invention relates to a device for determining quality criteria of a biomass.

The automated storage, drying and processing of biomass requires an unproblematic measuring system for determining quality criteria, such as moisture, concentration of various ingredients and ongoing microbiological conversions.

With the known analysis methods, only local measurements of individual parameters are possible, these measurements requiring complex manipulation of the material to be measured. The informative value of these selective measurements for the totality of the biomass or solution to be checked, which may be inhomogeneous, is not particularly high and depends relatively strongly on the choice of the area to which the measurement relates relates. The same problems arise when examining biological processes, e.g. Fermentation processes or the like

The aim of the invention is to avoid these disadvantages and to propose a device of the type mentioned at the outset, which makes it possible to easily add the average value of the quality criteria to the entirety of the biomass located in a container or in a limited space determine.

This is achieved according to the invention in that an electrode arrangement, between the electrodes of which the biomass to be tested is arranged, is provided, which electrodes are connected to an alternating voltage source supplying signals with a variable frequency and are connected to an evaluation circuit, one of which also Sequence control controlling the AC voltage source has controlled evaluation circuit which assigns experimentally determined quality criteria to corresponding values.

The relevant quality criteria of biomass, such as moisture, chemical change, concentration of certain substances, etc. influence the electrical conductivity of the biomass in a broad spectrum of the measuring frequency. These electrical properties of the biomass, which change with the change in the quality criteria of the biomass, can be detected and implemented in a simple manner with the device according to the invention. be evaluated. It is only necessary to first determine the corresponding evaluation tables by means of measurements and to register them in the evaluation circuits. Thus, the proposed measures make it possible to apply signals with a changing frequency to the entire biomass and to record the influence of these signals by the biomass.

According to a further feature of the invention, it can be provided that the evaluation circuit for measuring two different parameters of the signals picked up by the electrodes, e.g. the magnitude of the impedance and the phase rotation of the signal, preferably with an evaluation circuit connected downstream of each measuring circuit, and these evaluation circuits are assigned averaging devices which are connected to a display circuit.

These measures result in a considerable improvement in the accuracy of the measurement.

According to a further feature of the invention, provision can be made for an evaluation circuit to be connected downstream of each measuring circuit and for these evaluation circuits to be associated with averaging devices which are connected to a display circuit.

These measures make it possible to detect changes in the mass to be examined, which require a frequency-specific shift of peak values of the output signal of the evaluation circuit, in a very simple manner. Here, e.g. the frequency-related position of a peak value of defined amplitude is determined and an output signal proportional to it is generated, values lying outside a defined zone e.g. can be rated with 0, whereas the values within the defined range can be rated linearly from 0 to 1. The output signal of the evaluation circuit is then proportional to the area under the peak of the measurement signal and proportional to the frequency position. The averager acts as an integrator over the frequency.

According to a further feature of the invention, it can be provided that the electrode arrangement is formed by an essentially cylindrical jacket-shaped electrode and a central electrode arranged within the same. As a result, it is possible in a simple manner to apply the signals to the entire biomass and to detect and evaluate their changes based on the changing quality criteria of the biomass.

It can further be provided that an electrode is formed by an electrically conductive coating on the jacket of a biomass container, which results in a very simple construction.

It can further be provided that one electrode is formed by an electrically conductive coating of a biomass container and the other by an electrically conductive coating in the area of the bottom or the top of the biomass container.

This solution also leads to a very simple design of a device for monitoring quality criteria of biomass.

According to a further feature of the invention, it can be provided that at least one electrode is divided into a plurality of sections which are insulated from one another and can be controlled via a multiplexer and, if appropriate, a buffer amplifier.

These measures also make it possible to capture the quality criteria of the biomass in certain areas. This is particularly advantageous if the biomass is stored in large containers, or if changes in the biomass are to be detected that are slowly developing through the entire mass, e.g. begin in the middle of the accumulation of biomass and continue to the outside.

Furthermore, it can also be provided that an electrode arrangement consisting of at least one electrode and at least one counter electrode and shielding electrodes is, if appropriate, slidably arranged in a container holding a biomass.

These measures ensure that the field of the electrode which is developing, from which the measurement signal is taken, is brought into a certain shape by the shield electrodes, whereby measurement errors due to an uncontrolled change in the field of the electrode are avoided.

With a displaceable arrangement of the electrode arrangement, it is possible to have a larger accumulation of biomass, or to examine a solution in a larger container in sections for its quality criteria.

The invention will now be explained in more detail with reference to the drawings. Show:

1 to 3 different embodiments of electrode arrangements,

4 to 7 multi-part electrode arrangements, FIG. 8 shows a block diagram of the control of the electrode arrangement,

9 to 11 details of different assemblies, FIGS. 12a and 12b diagrams of different sugar solutions,

13a and 13b diagrams of different concentrations of apple cider vinegar,

14a and 14b are diagrams showing the course of fermentation of grape must, the diagrams provided with the index a the change of the signals in relation to their amplitude and the diagrams provided with the index b the change of the signals in relation point to their phase rotation as a function of the frequency of the signal and

15 is a graphical representation of a drying process of hay.

In the embodiment according to FIG. 1, two essentially cylindrical electrodes 15, 16 are provided, between which the biomass 17 is introduced. These electrodes 15, 16 are connected to a control. This embodiment is particularly suitable for monitoring biomass stored in a silo, the walls of the silo being able to be covered or covered with an electrically conductive coating or a film which forms the electrode 16.

The embodiment according to FIG. 2 differs from that according to FIG. 1 in that the two electrodes 15, 16 have an irregularly shaped cross-sectional shape. The electrodes 15, 16 can e.g. be formed by electrically conductive foils, one of which is inserted into a cluster of the biomass 17 to be examined and the other envelops it. With such an arrangement, e.g. a bundle of hay or straw, the moisture content of which is checked.

In the embodiment according to FIG. 3, the electrode 15 is dome-shaped, the second electrode 16 is arranged on the floor 21 in the center of the space enclosed by the electrode 15.

In the embodiment according to FIG. 4, an electrode 22 enclosing a space is provided, the electrode 23 arranged in the interior of this space being subdivided into a plurality of partial electrodes 23a to 23d arranged along the axis of the space delimited by the electrode 2. These partial electrodes 23a to 23d are connected to the outputs of a multiplexer 24 which is connected on the input side to the control. A buffer amplifier 25 is also provided.

There is a potential difference between the active and the inactive measuring electrodes, potential lines running along this potential difference, which leads to field distortions in the edge region of the active measuring arrangement. As a result, the measurement result would contain the state of the volume to be recorded and additionally also information from undesired measuring ranges. The buffer amplifier 25, whose gain factor should be as one as possible, prevents field distortions in the edge region of the measuring electrode. The buffer amplifier 25 is used to apply the potential of the active measuring electrode to the other, but not active, electrodes which are assigned to other measuring areas. The inactive measuring electrodes act as shielding and prevent field distortions, the measuring signal of the active arrangement being unaffected.

A similar electrode arrangement is shown in FIG. 5. However, the subdivisions of the electrode 23 run in the axial direction, so that the biomass located between the electrodes 22, 23 can be monitored sector by sector with regard to certain quality criteria, the sectors being different Extend over the entire length of the electrode arrangement.

FIG. 6 schematically shows an electrode arrangement in which a cylindrical electrode 23 is divided into three partial electrodes 23a, 23b and 23c in the axial direction. The individual partial electrodes 23a, 23b, 23c can also be subdivided in the circumferential direction, so that individual sectors can be examined in layers.

FIG. 7 shows an arrangement similar to FIG. 6, but with the center electrode in partial electrodes 23a, 23b, 23c is divided in the axial direction, the partial electrodes 23b and 23c being connected as shield electrodes. In addition to the electrode 23a, the shield electrodes 23b and 23c are also connected to the buffer amplifier 25. The entire electrode arrangement 23a, 23b, 23c can be displaced along the central guide rod 27.

8 shows an embodiment of an evaluation circuit.

A sequence controller 1 is connected to an AC voltage generator 2, which supplies a preferably sinusoidal signal with a variable frequency, the frequency preferably fluctuating between 10 Hz and 10 MHz, or this range being continuously traversed. An impedance measuring device 3 is connected to this alternating voltage generator 2, to which the electrode arrangement 22, 23 or 15, 16 is connected.

The impedance measuring device 3 has two measuring circuits, one of which detects the amount of the impedance of the biomass located between the electrodes 15, 16 and 22, 23 and the other detects the phase shift caused by this impedance. To each of the two outputs of the impedance measuring device 3, evaluation circuits 5 _X , 5 _S , 5 _{3 are} connected, which are further connected to the sequence controller 1. These evaluation circuits convert the measurement signals into signals corresponding to the quality criterion to be examined, the conversion being carried out according to empirically determined values which were determined with the aid of conventional point measurements.

With this arrangement it is possible in a simple manner to implement frequency-related window functions. For example If the data within a spectrum is rated 1 and outside a measuring range 0, then only data from a selected range of the entire spectrum are fed for further processing. For the use of the device, this means that from the entire information available, such as e.g. 12a, 12b, 13a, 13b, 14a and 14b is contained in the diagrams, individual information about e.g. Molecular structures, etc. can be derived.

The two evaluation circuits 5_. a mean value generator 6 is connected downstream, whereas the pairs of evaluation circuits 5-, 5 ₃ each have a peak value generator 7, 8 is switched, the peak value generator 7 being provided for the formation of the positive peak value and the peak value generator 8 for the formation of the negative peak value.

As can be seen from FIGS. 12a, 12b, 13a, 13b, 14a, there is a frequency-specific shift of peak values. If the position of a peak value of defined amplitude is to be determined in relation to frequency and an output signal proportional to it is to be generated, the signals outside this zone are evaluated with 0. Within this zone, the values are rated linearly from 0 to 1. The output signal of the evaluation circuit is then proportional to the area under the peak of the measurement signal and proportional to the frequency position, the mean value generator acting as an integrator over the frequency.

The outputs of the peak value formers 7, 8 and of the mean value formers 6 are connected to evaluating summers 9a, 9b.

This enables an extension of the assessment of the measurement signal, whereby information is obtained that is only frequency-proportional. If such information is available, the peak value is weighted by -1 by a window function of the associated evaluation circuit and is thus subtracted by the end summers 9a, 9b. The output signal is then only proportional to the frequency position and independent of the amplitude.

By means of the device according to the invention, measurement curves can be examined according to various, application-specific criteria. Here, e.g. Slumps in curves are evaluated and filtered out using the negative peak value generator 8.

The summer 9b is also connected to a comparator 12, the second input of which is connected to a reference value generator 10 which defines the measuring range limits, the comparator preventing the switching to a display 13b if the measuring range is exceeded, which is an indication of incorrect measurements . In the normal case, the output signal of the summer 9b passes via the comparator 12 to an output stage 11b and to the display 13b and to an interface 14.

The output signal of the summer 9a is connected to an output stage 11a, which is connected to a display 13a and the interface 14. 9 shows an example of a peak value generator. This essentially consists of a sample and hold circuit 30. This is supplied with a signal via a switch 31 controlled by the sequence control 1, the sequence control also being used to reset the sample and hold circuit 30 via the OR gate 32 worries. Furthermore, a comparator 33 is also provided, in the case of the positive peak value generator shown if the incoming signal exceeds the stored value, the signal is stored in the sample and hold circuit 30. In the case of the negative peak value generator, the connections of the comparator 33 are simply exchanged.

10 has an operational amplifier 40, which is fed back via a capacitor 41 and forms an integrator. This capacitor 41 can be bridged via a switch 42 controlled by the sequence controller for the purpose of resetting the integrator. The signal to be averaged reaches the operational amplifier 40 via a switch 43 controlled by the sequence controller and a resistor 44.

11 shows an evaluation circuit. This essentially consists of an EPROM 50 controlled by the sequential control system and a multiplier 51. An evaluation table is written into the EPROM, which assigns the individual measured values a corresponding value of the quality criterion to be examined. The multiplier 51 is a multiplying digital-to-analog converter. The effect of this is that the analog output voltage is proportional to a likewise analog reference signal or the input voltage multiplied by a weighting information or evaluation information. The weighting can e.g. according to a digital value, e.g. from 0 to 1 in 4048 steps with a 12-bit information structure.

In the proposed device, the raw data supplied by the measurement signals which are taken from the electrodes can be processed in a very flexible manner, which can be done according to very different criteria. It is only necessary that a reference curve for the given application is first determined empirically in order to serve as the basis for the evaluation of the measurement signals. This can be the course of drying, for example about feed, quality characteristics of a biomass, concentrations of certain solutions, etc. These reference curves, for example the phase profile of the signal during the drying of animal feed, are then either stored in a RAM or EPROM and serve as comparison values when evaluating current measurement curves. The advantage here is that the device can be adapted to the respective requirements without hardware modification.

12a shows the course of different sugar concentrations of sugar solutions as a function of the amplitude from the signal frequency.

FIG. 12b likewise shows the course of different sugar concentrations of sugar solutions, however, as a function of the phase shift on the frequency of the signal, whereby pronounced maxima and minima can be seen.

The spectra of these frequency-specific peak values are ideally suited for evaluating them in a simple manner.

13a and 13b show diagrams of the acid concentration of apple cider vinegar as a function of the amplitude or the phase rotation from the frequency of the signal.

Furthermore, the diagrams in FIGS. 14a and 14b show the relationships of amplitude or phase rotation and signal frequency of a fermenting grape must, recorded at different times.

15 shows the graphical representation of the relationship between frequency, phase shift and drying time of a continuous drying process lasting several hours.

It can be clearly seen that the phase shift undergoes significant changes with increasing drying time over a wide range of the frequency, so that clear statements can be made about the degree of drying.

Claims

PATENT CLAIMS

1. A device for determining quality criteria of a biomass, characterized in that an electrode arrangement, between whose electrodes (15, 16, 22, 23) the biomass to be tested is arranged, is provided, which electrodes (15, 16, 22, 23) are connected to an AC voltage source (2) supplying signals with a variable frequency and are connected to an evaluation circuit which is an evaluation circuit (5 _X. 5 _Z , 5 ₃ ) controlled by a sequence control (1) which also controls the AC voltage source. has, which assigns experimentally determined values corresponding to quality criteria.

2. Device according to claim 1, characterized in that the evaluation circuit circles for the measurement of two different parameters of the signals tapped by the electrodes (15, 16, 22, 23), e.g. the amount of impedance and the phase shift of the signal.

3. Device according to claim 1 or 2, characterized gekenn¬ characterized in that each measuring circuit is followed by an evaluation circuit (5 _lτ 5 _S , 5 ₃ ), and these evaluation circuits are assigned mean value formers (6) which are associated with a display circuit ( 13a, 13b) are connected.

4. Device according to one of claims 1 to 3, characterized in that the electrode arrangement is formed by an essentially cylindrical jacket-shaped electrode (15) and a central electrode (16) arranged within the same.

5. Device according to claim 4, characterized in that an electrode (15) is formed by an electrically conductive Be¬ coating the jacket of a biomass container.

6. Device according to one of claims 1 to 3, characterized in that an electrode (15) is formed by an electrically conductive coating of a biomass container and the other by an electrically conductive coating in the region of the bottom or the ceiling of the biomass container.

7. Device according to one of claims 4 to 6, characterized in that at least one electrode (23) is divided into a plurality of mutually insulated sections (23a, 23b, 23c, 23d) via a multiplexer (24) and optionally one Buffer amplifier (25) can be controlled.

8. Device according to one of claims 1 to 3, characterized in that one of at least one electrode (23a) and at least one counterelectrode (22) and shielding electrodes (23b, 23c) existing electrode arrangement, if appropriate, can be displaced in a biomass receiving one Container is arranged.