FURTHER OBSERVATIONS ON DRY LIME SCRUBBING 

 W. J. Lord, Bertrajn Gersten and J. W. Zahradnik 



A large percentage of our CA volume during this past storage season 

 was in rooms that were partly or completely lime scrubbed. With one ex- 

 ception, no difficulty was encountered with dry lime scrubbers in main- 

 taining the CO2 level below 5%, once this level had been attained. The 

 difficulty at this storage was corrected by changing the lime. Prior 

 to changing the lime at 6:30 P.M. on November 14, the CO2 level was 5.7% 

 and rising. By 9:00 A.M. the next morning, after changing the lime, the 

 CO2 had dropped to 3.5%. This indicates the feasibility of changing 

 lime during the storage season. 



Field Observations 



During October, IQeU, 30 lime samples were obtained from several 

 grower-owned storages for analysis of carbon dioxide content prior to 

 use in lime boxes. The CO2 content ranged from 0.71 - 1.6%. At the 

 end of the storage season, the CO2 content varied considerably from bag 

 to bag in the same lime box. For example, 3 bags of lime, each having 

 0.88% CO2 equivalent content prior to storage, analyzed 21, 29, and 31% 

 C0„ equivalent respectively, at the end of storage. At another storage, 

 3 Dags of lime with initial similar analysis had 15, 26 and 27% CO2 

 equivalent content after the storage season. Whether or not this vari- 

 ability is caused by variable air movement around the bags is not known. 



The effectiveness of lime placed in rooms to supplement the caustic 

 soda, water or dry lime scrubbers was variable, also. For example, one 

 room with 1/2 pound of lime per bushel of apples was caustic soda scrubbed 

 the 11th day after closing. At another storage, 1/2 pound of lime per 

 bushel of apples held the CO2 below 5.0% for 90 days. 



Placement of lime in rooms can result in a considerable saving in 

 caustic soda. As an illustration, one storage operator generally used 

 1000 pounds of caustic soda during the first 7 days after closing a 

 room of 17,500 bushel capacity. In 1964, 2000 pounds of lime was placed 

 in the room (0.1 pounds per bushel), and only 50 pounds of caustic soda 

 was necessary during the first 7 days after closing. After the first 7 

 days in 1964, the CO2 level was maintained with periodic charges of 50 

 pounds of caustic soda instead of 100 pounds every day. 



Assoc. Prof., Department of Plant and Soil Sciences 



Asst. Prof., Feed and Fertilizer Control Service and 



Assoc. Prof., Department of Agricultural Engineering, respectively. 



