Latest developments in Liquor Decolorization using Ion Exchange and Chromatography

摘要

Sugar refining is about decolorizing raw sugar in order to obtain a white product of the desired quality. Ion exchange decolorization is a state of the art technology to remove a significant portion of the color from liquors.Patented shallow bed technology in combination with fractal liquid distributors allows for designing high performance ion exchange systems operated with higher relative throughputs (bed volumes per hour) and consequently minimized relative process sizes. Very sharp liquid separation interfaces are achieved by plug flow in the resin columns. Altogether this results in smaller equipment sizes, decreased energy and utility demands (steam, electricity, water) and higher flexibility to varying raw sugar qualities.A consequent further development is the introduction of a simulated moving bed (SMB) chromatographic raw sugar separation system. Using the above mentioned shallow bed technology in an 8-cell SMB-separator setup results in 90 % decolorization of the filtered raw liquor with very low ash contents, high purities and no turbidity. SMB chromatography uses no chemicals and is a waste free process, producing a liquid product which can be directly sold to the customer. This technology allows for a refinery expansion without increasing the capital intensive process steps of the conventional system, particularly on the pan floor - crystallization and centrifugation with the connected steel structures and buildings. Raffinate, the decolorized liquid flow out of the chromatographic separator can be evaporated and added to the molasses since it has identical properties and value. While new to this application, SMB chromatography is proven technology having been used for a number of large scale separation tasks for over 30 years, such as desugarization of sugar beet molasses or glucose - fructose separation.SMB raw sugar chromatography complies with the increased demands today's refineries are facing concerning energy consumption, environmental requirements and product quality.