Food or edible material: processes – compositions – and products – Measuring – testing – or controlling by inanimate means
Reexamination Certificate
1999-09-14
2002-08-27
Yeung, George C. (Department: 1761)
Food or edible material: processes, compositions, and products
Measuring, testing, or controlling by inanimate means
C073S073000, C099S487000, C099S536000, C426S507000
Reexamination Certificate
active
06440475
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the field of grain conditioning systems and more particularly to a grain moisture measuring apparatus and method.
2. Description of the Art
Moisture control has always been a factor in milling. Grain purchased from a number of suppliers may have moisture content varying anywhere from 10 to 30 percent of its body weight. In flour milling, such variation in moisture can result in mill chokes or inferior or off-color product. In feed milling, such variation can result in waste due to brittle or improperly conditioned feed. This moisture variation can also vary the energy content of the as-fed ration, which causes variation in animal gain performance. Since the typical mill can process several hundred tons of grain every day, a mill may see fairly rapid swings over a relatively short time in the moisture level of the grain being processed.
To counteract this problem and in order to provide a mill with grain having a more uniform moisture level, grain conditioning systems have been proposed for tempering the grain before it is processed in order to increase its moisture level. A grain conditioning system adds a liquid to the grain as it is loaded into a grain elevator or as it flows into the mill. Typically, grain conditioning systems determine the amount of liquid to be added by measuring the moisture content of the dry (unconditioned) grain, the wet (conditioned) grain, or both dry and wet grain. Systems in which the amount of water added to the grain is determined by measurements of the moisture level of the dry grain are termed feedforward systems. Systems in which the amount of water added is determined not from the dry grain but from the moisture level of already conditioned grain are termed feedback systems. In practice, tempering has been shown to reduce mill stoppages and chokes due to fluctuating mill balance and improve both the efficiency of the milling process and the quality of the end product.
A feed forward system for controlling liquid added to a material such as feed grain during a conditioning process is taught generally by U.S. Pat. No. 5,194,275 to Greer. Greer discloses a feed grain delivery system in which dry grain readings are used to control the amount of moisture added to feed grain in order to raise the moisture content to a relatively constant target level. Since conditioning systems based solely on dry material readings do not measure moisture content in the conditioned product, such feed forward systems are susceptible to variations in the conditioning process due to temperature and changes in water pressure. Variations are also caused due to possible incomplete incorporation of added water into the grain (i.e., incomplete mixing of water and grain). These systems are unable to determine what, if any, effect the conditioning process is having on the material being conditioned and, therefore, cannot adapt to changing conditions.
A feed back system for controlling liquid added to grain during the conditioning process is taught generally in U.S. Pat. No. 3,732,435 to Strandberg, Jr. et al. Strandberg teaches the placement of a moisture sensor at the output of the moisture conditioner. The range at which water is added to or removed from the material is controlled by varying the speed at which the material is exposed to a constant flow of moisture or drying air. In another type of feed back system, a controller is used to adjust the amount of water added to a grain in order to bring the moisture level of the conditioned grain to approximately the target moisture level. U.S. Pat. No. 5,347,468 to Rupp et al. teaches a feed back system for controlling the addition of a liquid to a continuous flow of material and describes an algorithm for controlling the amount of water added during the hydration process.
Since, however, feed back systems do not track the moisture of incoming (dry) grain, they can be confused when wet grain moisture level readings vary due to changes in the dry grain moisture level. Additionally, the ability of feed back systems to track the target moisture level is compromised by the non-homogenized grain samples which have recently been wetted. In other words, the water on the outside and inside of the grain samples differs. The water absorbed by the grain is bound while the water remaining on the outside of the grain is unbound or “free” water. This “free” water is the root cause of erratic electrical characteristics of the grain samples in a feed back system. Furthermore, “free” water on the outside of grain “blinds” a capacitance type measurement which tends to show maxed out (invalid) readings with recently wetted samples. In general, “free” water complicates all types of moisture measurement, i.e., infra-red, microwave, or capacitance.
The erratic and unstable electrical characteristics of many materials immediately after the addition of water hinders the ability to obtain accurate, precise measurements of moisture content. Capacitance-type grain moisture measuring devices which treat a grain sample as a dielectric will not generally function properly unless the treated grain has had sufficient time to equilibrate and thus allow surface moisture to penetrate into the grain kernel. Typically, the equilibration times are on the order of hours. Such a time frame is not readily applicable to a grain processing environment where the continuous flow of grain being treated requires nearly instantaneous measurements of grain moisture levels to appropriately condition the grain as it moves through the system. If the treated grain is not allowed sufficient time to equilibrate, the erratic, unstable dielectric properties of the grain make it difficult to accurately measure the moisture level in the recently hydrated material. This instability becomes more apparent as the level of hydration increases. For these reasons, manufacturers will typically restrict a feed back system to use with products which absorb and stabilize moisture rapidly (such as soybean meal and mill feed).
It is apparent that feed back controlled grain conditioning systems, since they operate on the basis of the finished product, should be best capable of reacting to and compensating for changes in grain and water flow conditions. These systems, however, have been limited by their linability to accurately and efficiently measure the moisture level of recently wetted (unequilibrated) grain due to the unstable and erratic electrical characteristics of such materials. Additionally, the cost of such systems are typically higher than other types of systems.
There is a need for an apparatus and method for accurately measuring the moisture of grain as the grain moves through a grain conditioning system. Further, an apparatus and method is needed for accurately and efficiently measuring the moisture level of materials recently wetted to achieve a target level for moisture for the material.
SUMMARY OF THE INVENTION
The present invention provides a grain moisture measuring apparatus and method for measuring the moisture content of the grain as the grain moves through a grain conditioning system in which moisture is applied to the grain at a first location. According to one aspect of the present invention, the grain moisture measuring apparatus includes a sample extraction mechanism located at a point downstream from the first location where moisture is applied to the grain. The sample extraction mechanism extracts a sample of grain from the grain moving through the grain conditioning system. A grinding mechanism is connected to the sample extraction mechanism with the grain sample being transferred to the grinding mechanism which then grinds the sample to physically alter the sample. The apparatus further includes a moisture sensor positioned adjacent the grinding mechanism wherein the sample of grain is transferred to a location adjacent the moisture sensor after the grain sample is ground by the grinding mechanism so that the moisture sensor measures the moisture content of the grain sample. P
Claflin Joel
Greuel Pete
McNeff Clayton
McNeff Larry
Rupp Steve
Merchant & Gould P.C.
SarTec Corporation
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