高水分稻谷干燥工艺试验研究

Experimental research on drying technology for high moisture content paddy

针对中国南方地区稻谷收获季节需及时干燥高水分稻谷的市场要求,采用试验方法,在分批循环式稻谷干燥机上试验了低恒温干燥、变温干燥和变温干燥过程中增加缓苏时间的三种干燥工艺。依据试验结果,分析稻谷含水率、干燥介质温度、稻谷温度、缓苏烘干时间比等参数之间的联系与相互作用。试验表明:稻谷含水率高于21%时,降水速率可大于每小时1%,可采用60～70℃的介质。当稻谷含水率小于18%时,介质温度应小于60℃,降水速率小于每小时1%。当高水分稻谷进行了3～4次烘干缓苏后,利用中间缓苏仓增加缓苏时间,使稻谷内部与表层的温度、水分趋于平衡,有利于改善烘后品质和后续工艺的干燥降水。该结论对高水分稻谷干燥工艺设计和设备研制具有实用参考价值。

Aiming at the market demand that high moisture content paddy must be dried in time during the harvest in the south of China, three kinds of drying technologies, namely, low constant temperature drying, variable temperature drying and adding tempering time during variable temperature drying, were tested on the circulating batch paddy dryer. On the basis of tested results, interrelationship and interaction among parameters, such as paddy moisture, air temperature, paddy temperature, the ratio of tempering time to drying time etc., were analyzed. Tested results show that when the moisture content of paddy is higher than 21%, the drying rate can exceed 1%/h and 60-70°C air temperature can be used. When the moisture content of paddy is lower than 18%, air temperature should be lower than 60°C and the drying rate should be less than 1%/h. After three to four times drying and tempering for high moisture content paddy, adding tempering time by using middle tempering barn, temperature and moisture inside and outside paddy can tend to reach an equilibrium state, which is beneficial to improved drying quality of paddy and next drying process. Conclusions in this paper have practical value for drying technology design and equipment development for the high moisture content paddy.