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United States Department of Agriculture

Agricultural Research Service

Title: Further Insights on the Factory Performance of Cold, Intermediate, and Hot Lime Clarification Systems

Authors
item Eggleston, Gillian
item Monge, Adrian - CORA TX MANUFACTURING
item Ogier, Blaine

Submitted to: Zuckerindustrie
Publication Type: Abstract Only
Publication Acceptance Date: June 3, 2007
Publication Date: September 1, 2002
Citation: Eggleston, G., Monge, A., Ogier, B.E. 2002. Further insights on the factory performance of cold, intermediate, and hot lime clarification systems. Zuckerindustrie. 127:108.

Interpretive Summary: The clarification step in a sugarcane factory is very important in governing the quality and economic value of the final product, raw sugar. Presently in the U.S. most factories use the old clarification process of cold liming. This paper represents a comprehensive factory study to compare cold liming with the more advanced clarification methods of intermediate and hot liming. For most clarification parameters investigated, both hot and intermediate liming performed much better than cold liming, and hot liming generally offered extra economic and quality advantages over intermediate liming. By operating hot liming across the season, the reduction in sucrose losses alone saved the factory approximately US$283,000 over cold liming. Furthermore, by using hot liming, the factory observed 12-15% more heating capacity in the limed juice heat exchangers and a 90% reduction in the quantity of chemicals needed to clean the heat exchangers.

Technical Abstract: A comparative factory investigation of hot versus intermediate and cold lime clarification was undertaken. Hourly samples across each process were collected over a 6 hour sampling period, on 3 consecutive days respectively, and these were repeated 3 times across the 2000 grinding season. For most clarification parameters investigated, both hot and intermediate liming performed much better than cold liming, and hot liming generally offered extra advantages over intermediate liming. Less sucrose was lost to inversion reactions across both hot (av. 0.79%) and intermediate (0.97%) lime processes than across cold liming (1.48%). By operating hot liming, the reduction in sucrose losses alone saved the factory approximately US$283,000 over cold liming. Dramatically less lime had to be added in hot liming. Pre-heating 50% of the MJ in both intermediate and hot liming consistently removed color, dextran, and starch, but silicate levels were not significantly changed. Although, the fastest settling occurred in intermediate liming, equivalent to 2.1% (season av.) more turbidity removal occurred in both hot and intermediate liming compared to cold liming. Subsequent FES and raw sugar turbidity values were better in hot liming. Markedly less color (equivalent to 2.5%) formed on hot liming because of reduced retention time of liming. Using hot liming across the season, the factory observed 12-15% more heating capacity in the limed juice heat exchangers and a 90% reduction in the quantity of chemicals needed to clean the heat exchangers.

Last Modified: 10/20/2014
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