Handling Unacceptable Levels of Starch in Raw Sugar - One Refiner's Solution

摘要

The negative impact on cane sugar refining of excessively high levels of starch in raw sugar is fairly well known and has been debated over time. The topic of starch's impact in raw sugar has been the subject of numerous technical publications, including several SPRI research projects and previous SIT technical papers on raw sugar quality. Today's high cost of energy can easily result in a noticeable increase in refinery operating costs and lost efficiency when raw sugar starch levels exceed 250 ppm. Costly compromises are often made in the processing operation as the refiner typically experiences filtration difficulties while attempting to achieve an expected desired throughput at this (and higher) level of starch in the raw sugar.For nearly a year, detailed technical and operating cost data was obtained during the time unacceptably high starch cargoes were processed at one of ASR's carbonatation refineries. Concurrently, an investigation was undertaken to find a simple, rapid, correlated quantitative test method for starch measurement since no standard method was in use throughout the international sugar industry. As a result, ICUMSA method GS1-17, The Determination of Starch in Raw Sugar by the SPRI Rapid Starch Test (2004), was selected as our standard method.The objective of this effort was viewed as the basis for a potential raw sugar starch penalty which would be designed to recover the out of pocket increased costs while processing such problematic raw cargoes. Our previous efforts to discourage specific raw sugar suppliers from providing high levels of starch in raw sugar were not successful. Out of the necessity to remain competitive in the marketplace, we concluded the optimum solution was to develop and implement a purchase price penalty based on a raw sugar starch threshold level of 250 ppm.This paper describes the cause and effect process undertaken by ASR to define in economic terms the negative impact of high starch content raw sugar in processing, including details regarding measurements and the test method chosen. The outcome of this initiative resulted in the adoption of a progressive purchase price penalty for raw sugar exceeding 250 ppm starch via the SPRI Rapid-Starch method (ICUMSA method GS1-17), effective for raw sugar purchase contracts endorsed on/after 10/1/11.