Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 2/14/2005
Publication Date: 3/14/2005
Citation: Eggleston, G., Monge, A., Ogier, B. 2005. Calagem a quente (101 degrees C) e suas vantagens na produçao de açúcar [abstract]. Session 3, 26th meeting of Fermentec, Sao Pedro, Sao Paulo State, Brazil, March, 2005, Fermentec Publication. p. 2-3. Interpretive Summary:
Technical Abstract: From 1995 to 2000 a series of clarification studies were conducted at three Louisiana factories. These studies have had considerable impact with over 80% of Louisiana factories now changing from traditional cold lime clarification to hot or intermediate clarification. Here we report the final study of a comparative investigation of hot versus intermediate and cold 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 ~40.5 degrees C. For intermediate liming, 50% of the MJ was heated (82-93 degrees C) before incubation (8 min), then limed in a tank (4 min) at ~65.5 degrees C. Hot liming was configured very similar to intermediate liming except that incubation time as increased from 8 to 12 min, and that lime was added immediately after flash heating (101 degrees C; 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 intemediate liming, with the factory consuming, on season average, only 0.46 Kgs lime/ton cane compared to 0.58 for the previous grinding season when intemediate rather than hot liming was operated. 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 which settled faster and removed more inpurities, and only 30% preheating is required for improvements. The largest flocs and fastest settling occurred in intermediate liming, although more turbidity removal across the clarification tanks occurred in both hot and intermediate liming compared to cold liming, with better control. Markedly less color formed and dextran removal was the best across hot liming. Less sucrose was lost across both hot (season avg. 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 over cold liming.