DE1498863A1 - Method and device for determining the moisture content in tobacco - Google Patents

Description

Method and device for determining the moisture content in tobacco The invention relates to a method for determining the moisture content in tobacco in particulate form.

The invention also relates to one for determining attenuation device suitable for microwave energy through tobacco in particle form. ' In the Tobacco industry and. the moisture content is particularly important in the manufacture of cigarettes of tobacco is an important quantity, which is within narrow limits during the various Manufacturing steps can be controlled got to. The problem-the control the moisture content in tobacco is due to its hygroscopic property of tobacco is even more difficult. This is because tobacco can absorb moisture from the air easily absorbed and thus destroys that through the previous careful observation of the water content achieved equilibrium.

Another difficulty lies in the moisture content in cigarette tobacco in that uniformity is perhaps the most important factor in manufacturing of cigarettes is. The user of a certain type of cigarette does not expect any Change in smoke quality from cigarette to cigarette. The moisture content in tobacco can affect the quality of smoking and must therefore be carefully controlled A method of measuring moisture in the tobacco industry must be reproducible get accurate results.

If the accuracy of the method is poor, there is a control the moisture content is not possible within narrow limits.

When making measurements on any material in particulate form reproducibility depends on two factors, firstly the reproducibility the actual measurements and, secondly, the reproducibility of the PrO »a ' Therefore it is necessary that the sample to be measured be presented in a certain way and during the measurement is handled in a certain way.

It has. found that microwave energy Neßverfahren sur Determination of the moisture content of tobacco in particle form extremely suitable are assumed that certain procedures and devices are used.

Accordingly, it is an object of the invention to provide a re-modeable To create a method for determining the moisture content in tobacco in particle form, which is based on the measurement of the energy attenuation in the microwave frequency range, which causes attenuation as a result of energy runaway through a tobacco sample will.

Another object of the invention is to provide a device which sur measurement of the attenuation of microwave energy as a result of the passage by a Takakprobe in particulate form, which by the device Achieved improvement on the electronic reproducibility as a result of the elimination of variable sizes. like reflectivity.

Another object of the invention is to provide an improved one Sample holder for use in measuring the attenuation of microwave energy.

According to the invention, a method for determining the moisture content is provided created by tobacco in particulate form, in which a sample of a given weight of tobacco is provided in particulate form, the sample is placed in a holder and the holder is vibrated to be substantially uniform To achieve packing, the sample is compressed in the holder, among other things there. volume In the same way, reduce the sample to a known amount of microwave energy applied and the energy transmitted by the sample is measured in order to achieve the the weakening caused by the sample.

The invention also provides a device for measuring the attenuation of energy in the microwave frequency range of the electromagnetic spectrum as a result the passage of this energy through a, sample, which has: A source ion Microwave energy, e, e a radiating funnel, which is connected to the source is to concentrate the microwave energy in the sample, a receiving funnel, which is aligned with the radiating funnel and arranged so that he the absorbs from the sample through read microwave energy, facilities which with the receiving funnel-connected to the weakening caused by the sample determine su. a sample holder suitable for conducting microwave energy is1 fixed holding devices located near the hoppers1 as well as guide devices that are connected to the specimen holder and are suitable, to come into engagement with the fixed holding devices to the sample holder to be arranged reproducibly between the receiving and the radiating funnel so that the energy radiated from the radiating funnel passes through the sample holder step and hit the receiving funnel.

Under tobacco in particle form is a strip-shaped circuit Tobacco understood as it is commonly used to roll cigarettes.

The invention is explained in more detail, for example, on the basis of the Piguren. It shows: FIG. 1 a schematic representation in which the definition of the fur the use in an embodiment of the invention suitable electronic Components is shown; Figure 2 is an oblique view of the sample holder according to the invention and the adjustment device and other elements associated therewith according to the invention; FIG. 3 is a length of the line 3-3 in FIG. 2; Pigur 4 one Section along the line 4-4 and Pigur 3; and Pigur 5 is an exploded perspective view of an embodiment of the sample holder according to the invention.

The various electronic components are shown in FIG which is commonly used to measure the attenuation of microwave energy will.

In Figure 1, a Kylstron microwave oscillator 10 is provided, which generates energy in the microwave range.

The modulated power supply unit 11 supplies the required operating voltages bUr the oscillator 10 and generates a modulating voltage which causes Qnß the amplitude of the output of the oscillator 10 with a frequency in the audible range changes. The oscillator is preferably designed so that its frequency is in the range iat adjustable from about 8000 to 12000 megahertz, The microwave energy from the The oscillator 10 is placed in the ferrite directional switch 12 which is on the egg side directional element is used.

The energy is then fed into a variable attenuator 13 aum - leveling given. The attenuator 13 becomes sur precise control of the amplitude the microwave energy used.

The energy leaving the attenuator 13 is fed into a microwave antenna or a funnel 14, which focuses the energy su a bundle.

Your sample holder 15 is shown in the drawings that he di. absorbs energy transmitted through the funnel 14. The details of the Balters 15 are described below.

If the sample holder contains 15 material, which microwave energy absorbed, the beam leaving the holder 15 is weakened accordingly. The energy leaving the holder 15 is supplied by a further microwave antenna or a funnel 16 collected.

The energy collected by funnel 16 is passed into a precision attenuator 17 given. The purpose of the bypass tool 17 will be described later.

The energy leaving the attenuator 17 goes into a crystal detector 18 given, which rectifies the alternating input and generates an output, which pulsates with the listening frequency. with which the oscillator 10 is modulated.

The signal generated by the detector 18 is tuned by a low frequency amplifier 19 is amplified and the output of amplifier 19 is used for visual observation in the measuring device 20 given.

The various components shown in Figure 1 are natural connected to one another by conventional waveguide sections.

The device shown in FIG. 1 can be operated as follows briefly described. The attenuator 17 is set to have a predetermined one Weakening exerts on the energy given in them. When the sample holder 15 away. the attenuator 13 is set so that the measuring device 20 becomes a full scale reading results. Preferably the amplifier is with a gain adjustment provided, which serves to reduce the aging of the electronic components used, Correct measuring device deviations and the like, see below.

A sample of the material to be measured is placed in the holder 15 and the holder 15 is then inserted between the funnels 14 and 16. If accepted that the material in the holder 15 is suitable for absorbing microwave energy then the pointer of meter 20 will fall from its previous full scale deflection from and thereby indicates that the energy attaining the same is less is than the calibration value. Now the attenuator 17 is set so that the by the weakening it caused is reduced, and this adjustment will continue, until the pointer of the measuring device 20 has again reached the full scale deflection. This is now due to the absorption of the microwave energy by the sample in the holder 15 caused by the decrease in the attenuation caused by the attenuator t7 exactly canceled.

The attenuator 17 is provided with a precisely calibrated scale, see above that the change in setting can easily be determined. This attitude change the scale of the attenuator 17 then represents that by the absorption of the Nikrcwelle energy is the weakening caused by the sample in the holder 15.

For general purposes, the deviation of the needle of the measuring device 20 can be used as a measure of the weakening caused by the sample in the holder 15 caused. From a quantitative point of view, however, this is undesirable, since the reading is subject to errors and changes for many reasons9 for example the non-linearity in the detector 18 and / or amplifier 19 and the like.

By using the - de-energizer 17 to increase the in the crystal detector 18 given energy are all the components following the attenuator 17 returned the reference value which was present under calibration conditions was. With regard to details of the operation of a system as shown in Pigur 1 is, refer to the Massachusetts Institute of Technology Eadiation Laboratory Series 8, Principles of Microwave Cireuite, (Montgomery, Dicke sud Pureell) McGraw-Hill Book Company, Inc.

It is known that water reacts strongly to an alternating electric field ii microwave range responds. This response is due to the absorption of a Part of the energy due to the vibration characteristics of the water molecules.

Considering the mentioned property of water, microwave energy Absorbing becomes a practical method of measuring the water content a given material provided that no other element is present which also absorbs microwave energy. Need to continue to this procedure to use to determine the water content of a material, all other spoilers, which could influence the weakening, essentially switched off or on other way to be compensated.

The invention provides a method for determining the moisture content of tobacco in particulate form, which is proven to be reliable, reproducible and accurate exposed asked. The advantages of the invention reside in certain Process steps which are used in the actual determination of the weakening and also on the manner in which the tobacco sample is formed. Next @ is a novel sample holder was developed, which the accuracy of the invention Process improved.

Figure 2 is an oblique view showing the sample holder 15 and its Shows relationship to the other elements of the device according to the invention. figure 2 shows a support structure 21 in which the funnels 14 and 16 are arranged.

The holder 15 is shown in detail in Pigur 5.

A hollow cylinder 22 is provided to hold the tobacco sample. Preferably it is made of electrically conductive material to prevent leakage to prevent microwave energy through the walls. A disk 23 made for microwave energy Permeable material is used as a seal for the end 24 of the cylinder 22.

It is attached by screws not shown, which engage on the wall of the cylinder 22, and screw holes 25 are to this Purpose shown in disk 23.

The other end of the holder '15 is formed so that there is a subsequent su descriptive cover 26 accommodates.

For this purpose, the inner diameter of the end part 46 (Figure 4) of the holder 15 has been enlarged and therefore forms a shoulder 47.

The cover 26 has a cylindrical shape and consists of swei Parts of different diameters, the elongated part 27 having an outer diameter which is approximately equal to the diameter of the end portion 46 of the cylinder 22, whereby it can be used in the same. The wall thickness of part 27 of the Lid 26 is equal to the width of the shoulder 47. Therefore, when the lid 26 is in the Holder 15 is inserted, there is no discontinuity on the inner surface of the holder 15.

The larger diameter part 28 of the cover 26 is used in conjunction with the paragraph 47 as a stop, which a further movement of the part 27 into Inside of the cylinder 22 prevented. A disk 29 made for microwave radiation Permeable material is attached to the end 30 of the cover 26 and serves as a seal. It is noted that the distance between the disc 23 and the disc 29 is approximately equal to 80% of the length of the holder 15 be wears.

FIG. 4 is a section in which the holder 15 with the cover 26 is shown in place0 To hold the lid 26 firmly in place, fastening devices are provided. Appropriately, these fastening devices exist from a protruding hook 31 which is attached to the circumference of the cylinder 22, and a pawl 32 which is attached to the periphery of part 28 of cover 26 ist0 Since the hook 31 partially protrudes from the surface of the cylinder 22, slides the pawl 32 in frictional engagement therebetween. This arrangement is best can be seen from FIG.

The holder 15 is provided with handles 33, which slots 34 enthrj n @m m to explain the handling of the cylinder 22.

The handles 33 also form guide devices in each of the Handles 33 have a V-shaped slot 36 cut into them. Abutment 37 mAt reversed V-shapes are attached to the structure 21. as shown in FIG. When the cold 15 is inserted between the funnels 14 and 16 are the V-shaped slots 36 with the V-shaped abutments 37 in engagement, whereby the holder 15 in relation is placed on the funnels 14 and 16 in a reproducible manner0 In figure 2 there is shown a pair of resilient bumpers 38 associated with the structure 21 are connected.

These bumpers serve dasu, the holder 15 test in its place keep su

Support 39 are attached to the structure 21 and serve as a stop for Alignment of the holder 15 with the openings 40 and 41 of the funnels 14 and 16, respectively.

Figure 1 shows schematically the temperature indicator 42, welober with the Temperature probe 43 is connected. These elements are provided for a temperature measurement to be able to carry out the attenuation measurement at the same time.

Figures 2 and 3 show the arrangement of the temperature probe 43 in FIG with respect to the other elements of the device. About the interaction with the microwave field mini times su, the longitudinal axis of the probe 43 should be parallel to the magnetic field vector aligned with the microwave energy. The temperature probe 43 is a fast one responsive probe with a tip 45, which has a temperature-sensitive thermistor contained.

As shown in Pigur 49 the holder 15 is provided with an opening 44, welohe sur recording the temperature probe 43 is suitable. Therefore, when the holder 15 through the Guides 36 and 37 is the opening 44 Arranged to receive the temperature probe 43. iigur 3 shows the probe 43 in their position il Kalter 15.

The temperature sensed by the probe 43 is derived from the temperature indicator 42, which is shown schematically in Pigur 1.

By measuring the temperature of the sample at the time of the attenuation measurement can be any non-representability of the microwave absorption due to temperature fluctuations turned off. A temperature calibration map of the correction factor temperature versus Moisture can be obtained as follows. There are tobacco samples with different Proficiency wages established. Microwave attenuation measurements are then made in accordance with the procedure described here on the tobacco samples at various Temperatures running. The moisture content in the tobacco samples is determined beforehand determined by quantitative analysis. Then a group of measurement results obtained which shows the changes in microwave attenuation for a sample of given moisture content. if the same at different temperatures is measured0 In this way, a set of curves in which the attenuation plotted against the moisture content at certain temperatures will.

The preferred method for measuring moisture in tobacco in Particle shape has several steps. First, a normal weight sample used. This normal weight should have a volume that roughly corresponds to the holder 15 fills in. In other words9 the Kalter 15 is placed in an upright position, with the disc 23 at the bottom and the cover 26 removed. Of the' particulate tobacco is aedant poured into the cold 15, the previously weighed sample essentially fills the cold.

An important consideration when measuring the attenuation of a sample is that the sample seal holes or excessively with respect to flour Areas bb uniform wiö is possible. For this purpose it is predicted that the Holder 15 on a vibrating surface, for example a conventional vibrating table, while the filling process is attached. This will reduce the tendency to form a inhomogeneous Prebe eliminated.

The sample in the holder 15 is then by the arrangement of the lid 26 compressed in its correct position in the cold 15. As can be seen from Figure 4, the disc 29 extends partially into the interior of the holder 15 when the lid 26 is correctly arranged in the holder 15. This will keep the volume of the sample in proportion to the relative dimensions of the holder 15 and the elongated Part 27 of the lid 26, i.e. compressed to a volume which is not smaller than about 80% of the uncompressed volume. It is believed, that the printing together of the sample for the reproducibility of the attenuation measurements according to the invention contributes.

The filled sample holder 15 is then between the radiating Funnel 14 and the receiving funnel t6 are inserted, as shown in FIG. The V-shaped slots 36 in the handles 33 engage the inverted V-shaped ones Abutments 37 and are therefore used in conjunction with the bumpers 38 and the Placing 39 the cold 15 between the funnels 14 and 16 is reproducible to arrange.

The attenuation measurement is now carried out. as described above 9 and the temperature measurement is carried out and, if necessary, a compensation is made.

As indicated above, the Aba's scale setting becomes weaker 17 is preferably used as a measure of the weakening caused by the sample. By suitable calibration methods, the scale of the attenuator 17 can be designed in this way9 that the moisture content can be read directly.

A possible source of error in the attenuation measurement with the invention Device relies on the non-reproducibility of reflected microwave energy.

Bo fled this error as little as possible, are the disc 23 of the holder 15 and the disc 29 of the cover 26 formed so that they have a Thickness of half a wavelength in the dielectric material from which the discs are made are made, measure at the frequency used.

Further, the corresponding openings of the funnels 14 and t6 are like this chosen so that they are almost equal to the inner diameter of the sample holder 15. Through this a tight upper parallel bundle is created so that essentially the whole microwave energy exiting the radiating funnel 14 through the sample in the sample holder 15 must go.

The shape of the specimen holder and its relative dimensions are also factors. which are important for achieving accurate attenuation measurements are. For example, a cylindrical sample holder is preferred to a square one, because the cylindrical cold can be filled more uniformly. The square corners a holder with a square cross-section tend to have irregularities and irregularities in and around the corners and therefore will have some degree of reproducibility lost.

The sample holder 15 should preferably have a length which is greater is than its diameter. If every sample could be found to have one ideally uniform, i.e. completely homogeneous structure, then the relative measurements of the holder have no meaning. The specified choice the relative dimensions of the holder 15 is based on the assumption that it is not possible is to achieve complete uniformity or homogeneity in the sample.

Every water molecule present in the sample has an absorption capacity for microwave energy, a sample holder designed to be safe all microwave energy occurring on all water molecules in the sample results in a true weakening of the sample. Ideally this could be done by a sample holder with an infinitely great length and an infinitely small cross-section is used would.

When filling a holder with practical dimensions, as shown in the As shown in the figures, it is possible to address the irregularities in two ways or a combination of these two types. First, the tobacco can be in particulate form exist in layers which are perpendicular to the 3ahn of microwave energy Each of these layers can be completely uniform. however differs Each layer differs in its density from each subsequent layer in this s the becbachiete attenuation of microwave energy would be the true average Weakening, since every section of the bundle of microwave energy is absorbed by the same Tobacco Gewixht goes and therefore by the same ansabl of Wassermlekdlen occurs or strikes them.

The second non-uniform condition would be. that the pack on some path through the sample holder 15 parallel to the bundle of microwave energy is uniform, but that every such path is different from every other path Having packing density. This can be explained by assuming that half of the interior of the holder 15, which is divided in the longitudinal direction, one clear and the other Half a second. has a different density. In this pall the measured swell would be do not represent the true average weakening.

In practice, the filling obtained is likely to have a combination both types of non-uniformity. Therefore, it is a factor of 9 the length of the specimen holder Make it 15 larger than its diameter in order to average as much as possible to obtain. It is obvious9 that with a very short sample holder Very difficult to average out irregularities of the second type described above would be.

Claims (3)

p a t e n t a n s p r ü c h e 1, device for determining the moisture content a Tebak sample in particle form by measuring the attenuation of microwave energy, which from the opening of a funnel radiator through one in a cold contain Taakprobe is blasted to open a receiving funnel, characterized in that that the cold consists of a straight cylinder made of electrically conductive material with a circular cross-section, the inner diameter of the cylinder substantially equal to the larger diameter of the openings of the microwave funnel is that the cylinder has end caps at each end which are suitable for microwave energy are permeable, and that holding devices to support the holder in the distance between the funnels without physical contact between the cold and the funnels are provided. 2. Apparatus according to claim 1, characterized in that the axial The length of the cylinder is greater than its diameter. 3. Device according to claim 1 or 2, characterized by @@@@ Temperaturführlerscnde, which extends through the turn of the cylinder, the axis of the probe runs perpendicular to the axis of the cylinder.