Patent Application
20170142892
The invention relates to a method with which it is possible during the dressing of seed stock to set the one specific degree of drying of the dressed seed stock. The invention also relates to a device with which the method according to the invention can be carried out, and to the use of this device.
For the dressing of seed stock, generally seeds, it is introduced into the tank of a dressing device, the dressing tank, and an aqueous dressing solution and/or suspension, also known for short as the dressing, is added, this tank or a part of the tank of the dressing device being moved, preferably rotated. The moving part of the tank may for example be the bottom of the tank. The movement of the dressing tank or tank part has the effect that the dressing is distributed uniformly over the individual seeds of the seed stock and remains adhering to them. Apart from water, among the ingredients contained in this dressing are agrochemical active substances, such as for example neonicotinoids, which are intended to have the effect that the seed stock and the plants growing from them are protected from pests and fungi. The dressing may also contain additives in a dissolved form or in the form of particles. These may be colourants, auxiliaries such as polymeric binders, mineral fillers and other additives. During the dressing, gas, with preference air, which may be at a higher temperature than the ambient air, that is to say may be preheated, is introduced into the tank of the dressing device in order to accelerate the drying of the dressing on the seed stock.
Dressing devices are known from the prior art, for example from DE4128258A1.
It is desired to end the dressing, including drying, i.e. the dressing process, as near as possible to when the dressed seed stock is of such a dryness that it is just pourable, that is to say that, under the respectively prevailing ambient conditions, such as temperature, relative atmospheric humidity and air pressure, the dressing no longer quite has the effect of making the seeds adhere to one another. If drying is continued beyond this degree of drying—the optimum degree of drying—on the one hand time and energy are wasted, on the other hand dust that contains active agrochemical substances is produced by the rubbing together of the dry, dressed seeds, and this dust can unwantedly get into the environment and cause damage there. It may however also be desired to set other degrees of drying as accurately as possible, for example in order to improve the resistance to abrasion during processing or the flow behaviour of the seed stock. These desired other degrees of drying—which may relate both to the degree of drying of the coating as a whole or to the degree of drying of the surface of the coating—are likewise referred to hereinafter as optimum degrees of drying.
It is known from the prior art that the dressing duration for the optimum degree of drying is determined empirically. In this case, the degree of drying and the pourability of the seed stock are determined after various dressing times and used to determine the optimum dressing time for a specific degree of drying. This method has the disadvantage that on the one hand it is complicated, due to the necessary preliminary tests, and on the other hand it is susceptible to errors, since the dressing duration is highly dependent on parameters that are variable and difficult to influence, such as the temperature of the seed stock and of the ambient air and also in particular the prevailing atmospheric humidity. This may have the effect that the dressing duration determined is too short or too long. In addition, even during the tests for determining the dressing duration, dust is unnecessarily produced.
It is also known from the prior art that the degree of drying of the seed stock during the dressing process is determined by connecting to the dressing device a dust measuring unit, which checks the progress of the drying in the dressing process on the basis of the production of dust and interrupts the dressing process when a specific amount of dust is produced. However, with this method the dressing process is often interrupted too late, since the development of dust must occur before the dressing process is interrupted.
It is also known from the prior art that the moisture of seed stock can be determined with the aid of capacitive, microwave, photometric or spectroscopic moisture measuring methods. These measuring methods have several disadvantages, including:
The most accurate method known from the prior art for detecting the optimum degree of drying in dressing is for this degree of drying to be discerned by a skilled person from variation in the development or noise, that is to say also variation in the development of sound, during the dressing process. The different surface roughnesses of the dry undressed, moist dressed or dressed dried seed stock lead to a variation in the flow profile of the seed stock in the dressing device and to rubbing of the seeds against one another and against the wall. This is accompanied by variation in the development of sound caused by the movement of the seed stock in the dressing device during the dressing. For instance, this development of sound is drastically reduced if the dressing is initially added all at once and increases again during the drying. However, this method is on the one hand highly dependent on the hearing ability, the experience and the form on the day of this skilled person, and consequently poorly reproducible, on the other hand undeniably very personnel-intensive, and consequently cost-intensive.
The object of the present invention is to overcome the disadvantages of the prior art. In particular, the object of the present invention is to provide a device and a method with which the optimum degree of drying of the seed stock in a dressing process can be set.
The object is achieved by a dressing device with which in a dressing process the optimum degree of drying of the dressed seed stock can be set, comprising a measuring and controlling device, and by a method with which the optimum degree of drying of the seed stock in a dressing process can be set by using this measuring and controlling device.
Examples of the measuring and controlling device according to the invention—without restricting the invention to them—are:
Apart from the measuring unit, the measuring and controlling device also comprises at least a converter, which converts the value of the measured measuring variable (that is to say for example the sound, speed, filling level, torque, effective power or electrical power consumption) into an electrical or optical signal, an evaluation unit and a signal output. This signal output is connected to the dressing device, in particular its controller, in such way that, by outputting a corresponding signal from the signal output, the dressing process is interrupted. After that, the dressed seed stock can be removed from the dressing device. Alternatively, the seed stock may be subjected to a further dressing operation in the same dressing device, with a dressing of the same composition as in the previous dressing operation or with a dressing of a different composition than in the previous dressing operation, and/or is subjected to a further chemical and/or physical treatment.
Chosen according to the invention as the measuring variable is one that varies during the dressing process according to the degree of drying. It has thus been surprisingly found for example that
The dressing device may also have a number of measuring and controlling devices that measure the various measuring variables of which the value depends on the degree of drying of the seed stock during the dressing process.
With preference, the measuring and controlling device comprises an electroacoustic device. Such an electroacoustic device preferably comprises as the measuring unit a vibration pickup or an acceleration pickup, in particular a sound pickup. In the case of the electroacoustic device according to the invention, the measuring unit and the converter preferably form one unit in the form of a microphone, in particular a contact microphone.
The sound pickup is positioned such that it can pick up the sound that is caused by the seed stock located in the dressing device. Thus, with preference the sound pickup is attached to the dressing device, with particular preference on a part of the dressing device that is not moved, for example its outer wall. This has the advantage that the sound pickup is disturbed only little or not at all by sound or other vibrations or influences from the surroundings.
According to the invention, the sound pickup may also be positioned in the dressing tank. This has the advantage that the sound caused by the seed stock reaches the sound pickup with very high intensity.
According to the invention, the sound pickup may also be positioned in the vicinity of the dressing device. This has the advantage that no fastening to or in the dressing device has to be provided for the sound pickup.
Alternatively, the measuring and controlling device comprises one or more of the devices selected from the group of the following devices:
The invention also concerns a method for setting the optimum degree of drying of seed stock in dressing processes. In the case of the method according to the invention, the optimum degree of drying of the seed stock is determined continuously by means of a measuring and controlling device connected to the dressing device on the basis of the measurement of a measuring variable of which the value varies according to the degree of drying in the dressing process. The optimum degree of drying is thereby determined and the dressing process is interrupted when this optimum degree of drying is reached. In this case, “continuously” means in connection with the measuring and controlling device that an operation takes place at least once every five seconds, with preference at least once every three seconds, with particular preference at least once a second and with most particular preference several times a second, in particular five to ten times a second.
The evaluation unit of the measuring and controlling device measures the measuring variable continuously and additionally has an algorithm that continuously evaluates the time-dependent variation in the measuring variable. The algorithm is started at the latest when the entire seed stock has been fed into the dressing tank, the latter is moving and the other devices of the dressing device, for example the motor and the air injection, have also been put into operation. The algorithm preferably also determines the then prevailing average value of the measuring variable and determines it is a basic value for the determination of the optimum degree of drying, in particular if the sound, in particular the sound level, the speed at which the seed stock moves when the tank or the moved part of the tank of the dressing device is moved, or the level to which the flow profile of the seed stock rises while it is being moved in the dressing device has been chosen as the measuring variable. Preferably, the average fluctuation of the value of the measuring variable is thereby also determined. When the dressing is added, the value of the measuring variable changes sharply.
Thus, for example, when measuring
Instead of a measuring variable itself, its 1st or 2nd derivative may also be determined. With the values obtained therefrom—if necessary after mathematical transformation—the same procedure as with the values of a measuring variable is followed within the scope of the present invention, in other words there is no distinction between the two.
Q is determined by calibration. Q is for example dependent on the dressing device, the type of seed stock, the type of dressing, the measuring variable chosen, the degree of drying that is regarded as the optimum degree of drying, and whether the degree of drying relates to the coating as a whole or only to the surface of the coating. Q preferably lies in the range from 20 to 60%, with preference in the range from 30 to 50%, with particular preference in the range from 35 to 45%. For the case where the degree of drying with which the seed stock is just pourable is desired as the optimum degree of drying, Q for the aforementioned measuring variables (1) to (3) is approximately 40%.
To sum up, the algorithm works as follows in the case of the measuring variables (a) to (c):
The output of the signal for interrupting the dressing process when the value of the measuring variable in accordance with (iii) is reached preferably has the effect that the dressing process is interrupted. After that, the dressed seed stock can be removed from the dressing device. Alternatively, the seed stock may be subjected to a further dressing operation in the same dressing device, with a dressing of the same composition as in the previous dressing operation or with a dressing of a different composition than in the previous dressing operation, and/or is subjected to a further chemical and/or physical treatment.
The point in time of the adding of the dressing may be transmitted to the measuring and controlling device by manual input, for example by pressing a button, by a signal of the controller of the dressing device to the measuring and controlling device, for example if the dressing is added by the dressing device automatically, or by an algorithm of the measuring and controlling device itself. This algorithm may for example work in such a way that, apart from the average value of the measuring variable after complete adding of the seed stock, the average fluctuation of the measuring variable before feeding in of the dressing is also determined. When adding the dressing, the value of the measuring variable falls by an amount that is greater than two times, with preference than three times, with particular preference than four times, with most particular preference than five times, the average fluctuation of the measuring variable before adding of the dressing. When the falling by this amount is reached, the algorithm interprets this as the adding of the dressing. As from the adding of the dressing, irrespective of how the measuring and controlling device requires this information, the algorithm determines the minimum value of the measuring variable after adding of the dressing. Alternatively, for determining the point in time of the adding of the dressing, the algorithm may work in such a way that it regards the absolute minimum of the first derivative of the smoothed curve of the measured value over time as being this point in time.
Consequently, the method for setting a specific degree of drying of seed stock in dressing processes comprises the following steps when (a) the sound, in particular the sound level, that is caused by the dressing device and/or parts of this device and the seed stock contained in the dressing device, (b) the speed with which the seed stock moves when the tank or the moved part of the tank of the dressing device is moved, (c) the level to which the flow profile of the seed stock rises while it is being moved in the dressing device or a measuring variable that behaves in a way analogous to the aforementioned measuring variables during the dressing process is used as the measuring variable:
Preferably, the sound, in particular the sound level, is chosen as the measuring variable.
Alternatively, the variation over time of the sound curve is used for determining the end point (1st mathematical derivative), in order to determine a threshold value for the switch-off. After adding of the dressing, a time t1 after the minimum of the 1st derivative is sought, this minimum being greater than two times, with preference than three times, with particular preference than four times, with most particular preference than five times, the average fluctuation of the first derivative of the measuring variable before adding of the dressing. The temporally associated sound value is defined as the threshold value for the end point. This may be weighted by means of the factor F in order to initiate an earlier or later switch-off. After a time t2, the threshold value is compared with the sound value at the particular time. The factor f is usually determined empirically, in order to adapt the algorithm optimally to a specific combination of dressing unit, seed stock and dressing solution. F typically assumes values in the range between 0.7 and 1.3, but may well also assume values in the range between 0.5 at 1.5. In an individual case, more extreme values are also possible in order to conduct the process optimally. If a factor F is determined, according to the invention the threshold value is corrected by multiplication by F.
The optimum end point is reached when the sound value is equal to or greater than the threshold value. The threshold value is newly determined each time the process is started. The algorithm may be used without any adaptations for different dressing units.
To sum up, the algorithm works as follows for the measuring variables (a) to (c):
This algorithm is described by way of example in
By contrast with the sound that is caused by the dressing device and/or parts of this device and the seed stock contained in the dressing device, the speed at which the seed stock moves when the tank or the moved part of the tank of the dressing device is moved and the level to which the flow profile of the seed stock rises while it is being moved in the dressing device, when measuring for example
To sum up, the algorithm works as follows for the measuring variables (d) to (f):
The output of the signal for interrupting the dressing process preferably has the effect that the dressing process is interrupted, alternatively is continued for a fixed or variable time and then interrupted. After that, the dressed seed stock can be removed from the dressing device. Alternatively, the seed stock may be subjected to a further dressing operation in the same dressing device, with a dressing of the same composition as in the previous dressing operation or with a dressing of a different composition than in the previous dressing operation, and/or is subjected to a further chemical and/or physical treatment.
Consequently, the method for setting a specific degree of drying of seed stock in dressing processes comprises the following steps when (4) the torque of the shaft that moves the tank or the moved part of the tank of the dressing device, (5) the effective power of the motor that moves the tank or the moved part of the tank of the dressing device, (6) the electrical power consumption of the motor that moves the tank or the moved part of the tank of the dressing device, or a measuring variable that behaves in a way analogous to the aforementioned measuring variables during the dressing process is used as the measuring variable:
Preferably, the effective power is used as the measuring variable.
This invention also concerns the use of the dressing device according to the invention and the method according to the invention for setting the optimum degree of drying of seed stock. For this purpose, the method according to the invention that is described above for setting the optimum degree of drying of seed stock in dressing processes is carried out with the dressing device according to the invention.
The following exemplary embodiments, drawings and diagrams are intended to illustrate the invention, without it being restricted to them.
Seed Stock Treatment with a CBT25
1st Step: Idling
2nd Step: Loading With Seed Stock
3rd Step: Adding of Suspension/Dressing
4th Step: Drying
5th Step: Discharge of the Seed Stock/Belated Discharge
The variation of the sound level is shown in
In
| Number | Date | Country | Kind |
|---|---|---|---|
| 14167870.6 | May 2014 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/060365 | 5/11/2015 | WO | 00 |
