Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
1998-11-24
2001-08-07
Epps, George (Department: 2873)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
C250S341100, C250S343000
Reexamination Certificate
active
06271521
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for optical determination of ingredients of a pourable product, in which the product, as a stream in a conduit, passes a measurement window, in particular for analysis by means of a spectrometer with a predetermined measurement duration for performing the analysis.
The invention also relates to a method for near-time optical determination of ingredients in the stream of a pourable product, preferably by spectroscopic processes, in particular NIR spectroscopy.
Such devices and methods are used for presentation of pourable product, also called bulk goods, for optical analysis, for instance by means of colorimetric processes but in particular also for spectroscopic optical analysis. Replicable presentation which has the least possible variance in the result for identically composed bulk products, presents problems especially for poorly flowing powdered bulk goods with very small particle size. Particular attention must therefore be dedicated to preparing the specimens. This can be assured in the laboratory by suitable manual handling of the specimens. Problems often arise, however, in near-time monitoring of continuous processes, that is, on-line, where the corrective influence of the human being is lacking. Spectroscopic monitoring of liquids is the state of the art. Although bulk goods are also flowable, nevertheless, unlike liquids, they exhibit a very widely scattered rheological behavior, depending on the existing environmental conditions. For instance, the internal friction in such pourable products varies as a consequence of humidity and temperature, particle size, relative density, particle shape, process control, and so forth. The electrical properties also play a role, since the particles stick together more strongly with a static charge.
In particular, a steady exchange of material at the measurement window is necessary so that the results of measurement will now be adulterated. Electrostatic charges can make the exchange of material still more difficult.
Compared with laboratory measurement, on-line measurement presents some additional problems, which unless they are solved make accurate measurement impossible. The product must be fed continuously to the optics, yet during the individual measurement cycles, lasting up to about 20 seconds each, the product must not be moved. Furthermore, it must be assured that the product is thoroughly mixed. Finally, the correct, replicable product consolidation has substantial influence.
In measurements, the tendency of bulk goods to partly stick to the measurement window presents very particular problems, because this additionally adulterates the result of measurement. In the prior art, such problems are solved in various ways.
To solve these problems, European Patent Disclosure EP 0 585 691 contemplates fluidizing the powder; that is, by blowing gases in, it is converted into a fluidized bed into which the measurement window of a spectroscopic analysis system plunges.
In another apparatus in accordance with International Patent Disclosure WO 95/24633, the stream of product is carried via a vibrating feed channel. The vibrating feed channel feeds the product horizontally. In the boundary walls of the vibrating feed channel, a measurement window is provided, through which the spectroscopic analysis is performed.
A measurement system of the present Applicant, known by the tradename InfraAlyzer 600, is constructed in a similar way. In it, an optical module with the measurement window is disposed above the vibrating feed channel. The vibrating feed channel serves to furnish the most constant possible layer thickness of the stream of bulk goods. Disposing the measurement window above the vibrating channel prevents soiling of the window.
Finally, British Patent GB 2 142 721 discloses an apparatus for measuring powdered material in which the material is moved past a measurement window in a conduit with the aid of a worm conveyor. During the measurement, feeding is interrupted.
A disadvantage of the known apparatuses is their relatively complicated construction, which requires major expense for apparatus and engineering. Furthermore, constant operating conditions can be assured only with difficulty.
SUMMARY OF THE INVENTION
The object of the invention is therefore to disclose another device of the type generically defined at the outset for determining ingredients of a pourable product that allows accurate measurement of various products at less effort and expense.
The generic method should furnish an operationally reliable constant mechanical quality of the specimen and thus less variance of the results of measurement.
The object in terms of the device is attained in a device of the generic type in question in that the stream at the measurement site has a flow direction with a component in the direction of gravity; a valve with an open position and a closed position is disposed downstream of the measurement window in the conduit; and a controller is provided, which is embodied to move the valve into its closed position at least for the duration of the measurement. The construction of this device is surprisingly simple and can be assembled at little effort and expense using the usual parts in such system construction.
Uniform consolidation of the product is reinforced if an overflow is disposed upstream of the measurement window. As a result, the static pressure in the bulk goods remains largely constant. A metering scales with a scales-controlled valve that interrupts the oncoming flow of further product once a predetermined fill level has been reached can thus advantageously be avoided.
In addition, in a further feature of the invention, for the sake of consolidation, it is provided that the conduit, in the region of the measurement window, is embodied as a movable container with preferably flat side walls, and a drive is provided for generating a vibrating motion of the container.
Continuous self-cleaning of the measurement window is attained in that the measurement window in the container has an angle of inclination to the horizontal that is equal to or greater than a slope gradient of the pourable product.
This self-cleaning of the measurement window is further reinforced if the container has a fall line in the vicinity of which the measurement window is disposed. In particular, the measurement window should be disposed in the projection of a fall conduit onto the horizontal plane. When the measurement container is filled, the bulk goods drop onto the window, thereby assuring the exchange of the product at the window.
The same purpose is served by the provision that the motion of the container has a directional component which differs from the direction of the normal to the measurement window face and preferably corresponds to the fall line of the measurement window face.
An explosion proof embodiment of the drive can be dispensed with, if the drive of the container is embodied as a pneumatic drive, preferably with a piston moved rectilinearly. Pistons of this kind, moved back and forth on a straight line by compressed air and whose reaction forces are intended to shake the container, are known as free-flight jolters. They have the advantage that the reaction forces, used to drive the container, act essentially only in the direction of motion of the piston. They can therefore be employed purposefully for consolidation and feeding of the product in the operating direction of the drive.
If this drive is operated such that the free-flight piston does not execute hard impacts but instead is merely reversed in its direction of motion by the air cushion, then advantageously, low-frequency vibration with especially readily replicable, mild consolidation is obtained.
In a further feature of the invention, it is provided that the spectrometer is an NIR spectrometer, in particular with a filter wheel. Such spectrometers are especially suitable in conjunction with the device of the invention, because they have relatively long durations of measurement.
During this duration of measureme
Hoyer Hartmut
Nehring Eckhard
Saathoff Joerg
Bran + Luebbe GmbH
Epps George
Hanig Richard
Striker Micheal J.
LandOfFree
Device and method for optically detecting the presence of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device and method for optically detecting the presence of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device and method for optically detecting the presence of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2518712