Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
2000-06-21
2003-10-07
Gagliardi, Albert (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
C250S338500, C250S339120, C250S339110
Reexamination Certificate
active
06630672
ABSTRACT:
This invention relates to a system and method for measuring a parameter of interest in a processing stream. In particular, the invention relates to the use of near infrared spectroscopy for the on-line measurement of a parameter of interest in a processing stream. More particularly, the invention relates to the use of near infrared spectroscopy for the on-line measurement of parameters of interest in sugar cane processing.
BACKGROUND ART
Processing of biological material such as plant material usually involves measuring parameters of interest in the starting material and through to the desired end product or products. The measurement of the parameters can be for process control or for monitoring the level of a component in the material.
Measurements are typically made on samples taken from the processing stream. Depending on the parameter being measured, there can be a delay in determining the value of a parameter, as a consequence of which the parameter is not determined in real time. Furthermore, a sample may not be truly representative of the bulk of the material being processed at the point of sampling.
There can be other difficulties with measuring parameters of interest in a processing stream by sampling. A particular field where such difficulties occur is sugar cane processing. Sugar and related products are provided by processing sugar cane in sugar mills where the cane is crushed and processed through to crystalline raw sugar and molasses. The cane is supplied by plantation owners or individual cane farmers with the owners or farmers being paid for the cane supplied on the basis of tonnage and quality.
In Australia, for example, the amount paid to a plantation owner or farmer for each parcel, of the supplied cane is determined by weighing the parcel and evaluating the sugar content of the cane. An industry-agreed value is then used to calculate the amount paid for the parcel, the whole process being referred to as the “cane payment scheme”. Various systems are used to determine the sugar content of the supplied cane. Each of the systems requires sampling, sample processing and analysis. In many countries, a core of cane is withdrawn from the delivered cane, processed by pressing or wet disintegration to juice which is analysed and converted to a measure of the sugar content of the cane.
The system used in Australia requires analysis of the earliest juice (first expressed juice) driven out of the cane crushing rollers. This entity has been shown to be convertible to and representative of the analysis of the whole cane. The cane payment system requires continuous sampling of the first expressed juice throughout the period of crushing each parcel of cane and an analysis reported for that parcel. Payment is based on this analysis and the weight of the parcel. The juice is subsampled and analysed according to standard proscribed methodologies for “pol” (a measure of the sucrose content of the juice) and “brix” (a measure of the dissolved solids content of the juice). The estimation of the total cane supply is determined by means of the first expressed juice analysis, the fiber content of the cane and empirically determined relationships linking the juice analysis and total cane analysis.
The fiber analysis of the cane for which the juice is sampled is determinable by washing a representative sample of the cane free of dissolved solids. The sample is prepared by cutter grinding to an appropriate fineness prior to washing. Sampling and analysis for individual parcels is not practical and a deemed fiber is used in calculations on an individual farmer's cane delivery.
Each variety of cane is allocated to one of two or three classes of more or less common average fiber composition. The deemed or “class fiber” as it is termed is a rolling average of the fiber of the class which has been allocated to the cane variety. The rolling average is obtained by regular sampling of each class throughout the day, compositing within the class and determination of the daily average fiber. Several days analyses are combined in the rolling average.
The use of class fiber is a particular weakness of the current system but is forced upon the system by financial and practical impossibility in providing a representative, meaningful individual fiber composition for each parcel of cane. Providing such representative and meaningful data in a typical Australian sugar mill would require the analysis of at least 150 parcels of cane each day, in duplicate, requiring a sampling team of approximately 30 persons, approximately 20 fiber analysing instruments and 4 to 5 cutter grinding machines.
The class fiber system also makes no distinction between the actual condition of the particular parcel of harvested cane in respect of dirt and extraneous matter content or in respect of inherent differences that may pertain to its plant or ratoon status.
Cane analysis is labour intensive and relies on extended sampling procedures, analysis and subsequent conversion to an estimate of the analysis of the whole cane received. The methodology in practical use does not give adequate feedback to the grower on cane quality or adequate feed forward for process control to the miller as it does not use individual parcel fiber analyses in the compositions.
Spectroscopy is a technique whereby a chemical compound can be identified by the degree of modification to light at different frequencies or wavelengths. Near infrared spectroscopy (NIR)—that is, spectroscopy where absorption of light over the range 400 to 2500 nm is analysed—has been previously applied as a tool in such fields as the measurement of protein and moisture in grain, the composition of forage for animal food, the degree of ripeness of fruit and the composition of fine cane particles, cane juices, syrups and sugars in sugar laboratory situations. However, NIR has not previously been exploited on-line for measuring parameters of interest in a processing stream such as comminuted sugar cane during cane processing.
SUMMARY OF THE INVENTION
The object of the invention is to provide a system and method for the on-line measurement of parameters of interest in a processing stream, which system and method utilise near infrared spectroscopy. A particular object of the invention is to provide a system and method for the on-line measurement of parameters of interest in sugar cane during processing of the cane utilising near infrared spectroscopy.
According to a first embodiment of the invention, there is provided a system for the on-line measurement of a parameter in a processing stream, the system comprising:
(a) a scanning head mounted adjacent a continuous stream of processed material, the scanning head comprising a remote light source and reflected light gathering and transmission apparatus;
(b) a near infrared spectrophotometer which includes a monochromator for resolving the reflected light into light of a discrete wavelength;
(c) a database containing a reference calibration equation linking absorption characteristics by wavelength and the quantified presence of the parameter of interest; and
(d) a computer for measuring the parameter by application of the calibration equation to the obtained spectrum for a sample and managing said system.
According to a second aspect of the invention, there is provided a method of on-line measurement of a parameter in a processing stream, the method comprising the steps of:
(i) obtaining an infrared reflectance spectrum from a stream of processed material;
(ii) applying an appropriate calibration equation to the spectrum to quantify the presence of the parameter of interest; and
(iii) statistically validating the spectrum obtained as being represented by the calibration equation.
According to a third embodiment of the invention, there is provided a system for the on-line measurement of a parameter in processed sugar cane, the system comprising:
(a) a scanning head mounted adjacent a continuous stream of processed cane, the scanning head comprising a remote light source and reflected light gathering and transmission apparatus;
(b
Atherton Philip Gwyther
Berding Nils
Brotherton George Alexander
Grimley Scott Clifford
Lethbridge Phillip John
Bureau of Sugar Experiment Stations
Gagliardi Albert
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