Evaluation of an Ethanol Detector for Stale Cane Identification at Noodsberg

Previous work has shown that there is a relationship between the degree of deterioration of cane and the amount of ethanol present. The use of an ethanol detector for identifying stale cane was investigated at Noodsberg. This tool will enable the cane quality controller to identify areas where cane delays occur and implement appropriate action. The detector uses the infrared absorbance of ethanol to measure the concentration of ethanol present in the air drawn through the instrument. Although this technique was shown to work exceptionally well in the laboratory, in a factory many practical problems can arise. The cane must be shredded, since little or no ethanol is released through the rind of the cane. Shredding releases moisture that, if not separated from the air sample, will accumulate on the optics and cause drift in the readings. The measurement is actually ethanol per unit volume; consequently, any pressure drop in the sampling system will cause a drop in the reading. Small pieces of fibre accumulating in the piping may allow fermentation of the sugar and lead to false ethanol readings. Temperature has a marked effect on the evaporation rate, and hence the ethanol present in the air sample. Compensation functions had to be included. This paper examines the test data that was collected to verify the detector’s ability to indicate ethanol in cane. The techniques used to prepare the air sample for the detector in continuous operating conditions are also discussed. The application of the detector will allow the prediction of problems in the processing of deteriorated cane and also give an early alert to cane quality monitors so that speedy corrective action can be taken along the supply chain.