Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/25/2006
Publication Date: 5/15/2006
Citation: Eggleston, G., Monge, A. 2006. Differences in the factory performance of cold, intermediate, and hot lime clarification processes in raw sugar manufacture. (Abstract). 2006 International Society of Sugar Cane Technologists Processing Workshop. p. 14.
Technical Abstract: From 1995 to 2000 a series of clarification studies were conducted at three Louisiana factories. These studies have had considerable impact in the United States, particularly Louisiana with 100% of the factories changing from traditional cold lime clarification to intermediate or hot lime clarification. Here we report the final study of a comparative factory investigateion of cold versus intermediate versus hot lime clarification at one factory. In cold liming, mixed juice (MJ) was incubated (8 min) and then limed in a lime tank (4 min), both at ~40.5oC. For intermediate liming, 50% of the MJ was heated (82-93oC) before incubation (8 min), then limed in a tank (4 min) at ~65.5oC. Hot liming was configured very similar to intermediate liming except that incubation time was increased from 8 to 12 min and lime was added immediately after flash heating (101oC; 30 sec). Overall, both hot and intermediate liming performed much better than cold liming, and hot liming offered some extra advantages over intermediate liming. Dramatically less lime had to be added in hot liming compared to either cold or intermediate liming. Preheating 50% of the MJ in both intermediate and hot liming consistently removed color, dextran and starch, but silicate levels were not significantly changed. MJ preheating created larger flocs that settled faster and removed more impurities, and only 30% preheating is required for improvements. The largest flocs and fastest settling occurred in intermediate liming, although significantly (P<.05) more turbidity removal across the clarification tanks occurred in both hot and intermediate liming compared to cold liming, with better control. Less sucrose was lost across both hot (season av. 0.8%) and intermediate (1.0%) lime processes than across cold lime clarification (1.5%). By operating hot liming, the reduction in sucrose losses alone saved the factory approximately (U.S. $283,000 using 2000 raw sugar prices of 19cents/lb). Savings were also found in less lime usage and cleaning chemicals for juice heaters.