Dual objectives of forage drying and insect disinfestation

Abstract

Rotary drum dryers are used to dry forage crops prior to compacting the dried biomass into compressed bales. Compressed bales are desirable for long distances transport. In Canada, forage grown in the field may blend with agropyrons and wheat plants that are host to pupae stage of quarantine insect Hessian fly (Mayetiola destructor, Say). A few of the importing countries like Japan and The Republic of South Korea specify that a dryer could destroy the insect, provided that the material is maintained above a certain temperature and for a specific duration. A field trial on a commercial rotary drum dryer operating in a hay processing plant in Rolling Hills, Alberta, was conducted. The tests established that the biomass experienced a temperature larger than 90°C for a period of longer than 100 s when the chopped hay passed through the dyer. A longer residence time was predicted when a cascading model computed residence time in the dryer. A simple formula was developed to estimate the residence time from throughput and the holding mass capacity of the drum and the cyclone.