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United States Department of Agriculture

Agricultural Research Service

Title: Preliminary Factory Study on the Performance of a Plate Evaporator and Robert's Type Evaporators with Emphasis on Sucrose Losses

item Eggleston, Gillian
item Endres, Trevor - RACELAND FACTORY

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2003
Publication Date: January 2, 2004
Citation: Eggleston, G., Endres, T. 2004. Preliminary factory study on the performance of a plate evaporator and robert's type evaporators with emphasis on sucrose losses(abstract). International Sugar Journal. 106(1261):44.

Technical Abstract: At the end of the 2001 grinding season, a full-scale Alfa Laval EC 700 plate evaporator was installed at Raceland factory, Raceland, LA, as a booster to the second effect Robert's-type Calandria evaporator. A factory study was conducted to determine the effects of time between evaporator wash-outs on overall performance of the plate evaporator and the Robert's-type evaporators, with an emphasis on sucrose losses. The factory evaporator station consisted of Robert's-type Calandria evaporators in series, with one pre-evaporator (25,000 ft2), followed by a first (21,000 ft2), second (17,000 ft2), third (12,000 ft2) and fourth (12,000 ft2) effect evaporator. Calculated retention times were 2.9 mins in the pre-evaporator, and increased from 2.7 to 8.9 mins across the other evaporators; retention time across the plate evaporator was only 1.1 mins. Numerous samples entering and exiting each evaporator were taken across two adjacent cleaning cycles (between Nov 20 and Dec 4). Gas chromatography was used to determine glucose, fructose, and sucrose concentrations. Changes in pH, Brix, and color were also monitored. Most sucrose losses to inversion occurred in the pre-evaporator where temperature and heating surface were the highest. The Plate evaporator improved the performance of the evaporator station and allowed the factory to increase their grinding rate. Generally, the plate increased Brix by ~ 4.5 Brix units, and % evaporation rate (equivalent to a % Brix increase) across the plate evaporator was ~ 11.5%. The plate evaporator, like the Robert's-type evaporators, was still susceptible to scaling, which caused sucrose losses to occur generally ~ 4 days after the last wash-out and became worse with prolonged use of the plate. Sucrose losses were consistently measured in the last evaporator at this factory, even just after a wash-out, which is a phenomenon that was not observed at another Louisiana factory.

Last Modified: 4/21/2015
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