Drying and gas or vapor contact with solids – Material treated by electromagnetic energy – Microwave energy
Reexamination Certificate
1998-05-27
2001-06-19
Wilson, Pamela (Department: 3749)
Drying and gas or vapor contact with solids
Material treated by electromagnetic energy
Microwave energy
C034S265000, C034S549000, C034S574000, C034S202000, C219S678000, C219S702000, C219S704000, C219S707000, C219S708000, C219S709000
Reexamination Certificate
active
06247246
ABSTRACT:
FIELD OF THE INVENTION
The instant invention relates generally to a moisture analyzer and, in particular, to a microwave moisture analyzer for loss on drying applications.
BACKGROUND OF THE INVENTION
A multiplicity of devices and analytical methods have been developed in an attempt to obtain fast and accurate quantitative analysis of a vast array of products which are manufactured subject to strict control of moisture. For example, certain products have a specific range of moisture which dictates the taste and/or texture of the product. Thus, once the consumer associates a specific taste and/or texture to the product the uniformity of that taste and/or texture becomes a hallmark to the product's long term acceptance and ultimate success. Furthermore, moisture content is a specific process control in food processing, waste water treatment and materials processing.
Typically, these products require the volatilization of moisture or the like from the substance for moisture determination. In recent years, conventional microwave heating has been employed in the methods to remove various volatiles such as moisture followed by calculations of the amount of moisture lost. Conventional microwave heating requires the use of high power levels for providing effective drying due to the conventional microwave oven's employing random direction T
e
waves as the dominant energy field for the drying process. As a result, these microwave ovens produce hot and cold spots, over heating edges and charring of the products being analyzed. In addition, these conventional microwave ovens failed to provide a satisfactory solution which provided fast and accurate moisture determination of the product without the degradation of the product due to these problems.
Thus, there continues to be a need for an efficient microwave moisture analyzer which offers uniformity of microwave heating and rapid moisture determining analysis without the degradation of the product due to these problems. This is particularly important in light of the fact that most of the testing of products is related to process control in some form or another. Thus, the speed of the analysis and tests are hallmarks of high quality mass production. In addition, there is a need for a microwave moisture analyzer which provides timely feedback for maintaining tight tolerances of both the process and product produced thereby. Furthermore, a microwave moisture analyzer is needed which includes automated functions which simplify routine analysis thereby substantially eliminating the dependency of the result of the analysis on the skill and care exercised by the operator.
In addition, scales have been employed within these conventional microwave ovens to measure the weight of the product being analyzed. However, these devices have heretofore been susceptible to jarring and vibration in the working environment which resulted in anomalous weight readings. Such inconsistencies in operation result in unpredictable and unreliable moisture determination of the product.
Furthermore, none of the prior art which applicant is aware addresses the problem of continuing to dry the product after all of the moisture has been exhausted therefrom. This of course alters the mass which introduces an error in the final moisture calculation. Moreover, none of the prior art which applicant is aware addresses the possibility of a sample igniting in the chamber while doing a loss on drying process. Although the possibility of a sample igniting in the chamber while doing a loss on drying process is low, it does exist.
Therefore, not only does there continue to be a need for an efficient microwave moisture analyzer which offers uniformity of microwave heating and timely feedback for maintaining tight tolerances of the drying process, there also continues to be a need for a microwave moisture analyzer which is impervious to vibration and jarring and which addresses the problem of over drying the product and the possibility of the product igniting in the analyzer.
The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant's acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed.
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SUMMARY OF THE INVENTION
The instant invention is distinguished over the known prior art in a multiplicity of ways. For one thing, the instant invention provides a microwave moisture analyzer for loss on drying applications which provides fast and accurate quantitative analysis of a vast array of products which are manufactured subject to strict control of moisture. The instant invention also provides fast and uniform drying of product samples for real-time process control without degradation of the sample due to charring. In addition, the instant invention provides microwave energy means for providing real time feedback during the drying process of the sample thus, inter alia, maintaining tight tolerances of the drying process. Furthermore, the instant invention provides a microwave moisture analyzer which is impervious to vibration and jarring in the working environment thereby eliminating anomalous weight readings which result in unpredictable and unreliable moisture determination of the sample. Moreover, the instant invention solves the problem of over drying the product and the possibility of the product igniting in the analyzer. The instant invention also includes automated functions which simplify routine analysis thereby substantially eliminating the dependency of the result of the analysis of the skill and care exercised by the operator.
In a preferred form, the microwave moisture analyzer of the instant invention includes, a power supply, a magnetron, a power module operatively coupled between said power supply and said magnetron for driving said magnetron, a wave guide communicating with the magnetron and with a microwave containment chamber for delivering energy thereto, at least one microwave energy sensor for sensing microwave energy or magnetic and/or electric field strengths within the chamber for controlling, inter alia, the loss on drying process of the sample being assayed and determining when the drying process is complete. A precision electronic balance is operatively disposed within the microwave chamber for allowing a specimen being assayed to be weighed. In addition, a ventilation chamber is provided for venting moisture from the microwave chamber. A processing unit and associated memor
Claesson Jan
Harbert Douglas E.
Holzschuh Tim
Maple Martin L.
Playen Thomas G.
Denver Instrument Company
Kreten Bernhard
Wilson Pamela
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