Study On Alfalfa Drying Base On The Four-fold Rotary Dryer And A Design Of Its Auxiliary Equipment

With the rapid development of forage processing industry, forage dried by the artificial method has become a necessary pre-processing method. High quality forage can be obtained by both advanced drying equipment and reasonable forage drying process. The effect of input parameters, including feeding rate of fresh alfalfa segments, hot air flows, roller speed, was analyzed on the quality index, and the optimum drying parameters of alfalfa were determined. The quality index was consisted of the moisture content (MC) of alfalfa and nutritional qualities, including crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ash (ASH), calcium (Ca), phosphorus (P), digestible dry matter (DDM), dry matter intake (DMI), and the relative feeding value (RFV).The characteristics of alfalfa dried by the four-fold rotary dryer were studied. The results showed that feeding rate, hot air flows, roller speed had significant influences on the moisture content and the nutritional quality of alfalfa dried. A comparing experiment was employed to analyze the quality of alfalfa dried between the rotary drying and natural drying method. The results suggested that the qualities of alfalfa dried by the rotary dryer were superior to that of the natural drying. The preservation rate of CP obtained by the rotary drying was up to 98.11% of fresh alfalfa, and was higher than 12.13% preservation rate by the natural drying. NDF of rotary drying was slightly higher than the fresh grass, while the natural drying was the highest and up to 57.96%. Comparing with the rotary drying method, ADF obtain by the natural drying increased by 6.02%. Based on the calculated results, DDM, DMI, RFV in the rotary drying samples were also significantly higher than that in the natural drying samples.A Central Composite methodology design was employed to determine the effect of the experimental factors, including feeding rate, hot air flows and roller speed, on the quality of alfalfa dried, and develope the regression models of MC, CP, NDF, ADF, DDM, DMI, RFV, ASH, Ca and P. The results showed that the highest content of CP was obtained in the condition of 36 kg/min feeding rate, 60% hot air flows, and 13r/min roller speed; The lowest content of NDF was arrived when feeding rate was 27 kg/min, hot air flows was 63%, and roller speed was 11r/min; the lowest content of ADF was got by 34 kg/min feeding rate, 65% hot air flows, and 11r/min roller speed. According to the requirement of each nutritional index, the optimum processing parameters were obtained as follow: feeding rate was 24 kg/min, hot air flow was 60%, and roller speed was 10 r/min. And the nutritional index were obtained as follow: MC 13.26%,CP 21.13%,NDF 48.03%, ADF 30.47%,DDM 65.16%,DMI 2.46%,RFV 124.26. The verification experiment showed that the results of the verification experiment were accordance with that of the theoretical prediction, and the relative error was lower than 5%.As a affiliated part of the four-fold rotary dryer, a forage crushed machine was designed and manufactured. It can be used to stave the alfalfa without drying. The treatment can accelerate the drying rate, and decrease the difference of drying rate between stems and leaves of alfalfa, as well as improve the uniformity of moisture in alfalfa. The results suggested that the technical can be used as the basis of industrialized produce.