Crushed Cotton Stalk Hot-air Drying Properties And Design Of Crushed Cotton Stalk Drying Kiln

Cotton stalk scrimber has comparable properties with wood-based composites and itsfabrication is a new effective way to utilize the cotton stalk resources. In order to use thecotton stalk which is abandoned crop straw to manufacture scrimber and solve the question offorest resources insufficiency, this study investigated the effects of hot-air drying parametersincluding temperature, wind speed, initial moisture content based on dry weight and formingload on drying rate of crushed cotton stalks, thus obtaining data for optimizing drying processand designing drying device.Besides, the strength characteristic of crushed cotton stalk dried by hot-air was analyzed.Single factor and orthogonal experiments were implored on a digital experimental platformwith a cavity inside. This study includes four sections, hot-air drying characteristic of crushedcotton stalks was analyzed in the first section; mathematical model of crushed cotton stalkswas established in the second section; after drying, strength characteristic of crushed cottonstalks was investigated in the third section; the drying kiln of crushed cotton stalks wasdesigned in the fourth section. The results are as follows:(1)The process of hot-air drying of crushed cotton stalks is falling rate drying process,controlled by internal moisture diffusion. The entire drying process was without the stage ofconstant rate of drying and the drying rate was controlled by the internal moisture diffusionrate.(2)Hot-air temperature and wind speed are two important indicators in the process ofhot-air drying of crushed cotton stalks. The termination time of hot-air drying of crushedcotton stalks was increased with intial moisture content and forming load, while decreasedwith increasing wind temperature and wind speed. When the initial moisture content was100%, forming load was7.9kg/m2, wind temperature was120℃, wind speed was2.6m/s, therequired drying time was12minutes to finish drying process, and after that, the moisturecontent of crushed cotton stalks was6%.(3)Through variance analysis of orthogonal test results, the influence of termination timeof drying and energy loss in the drying process of wind temperature, initial moisture content and forming load had a significant level, comparing to wind speed. The optimal parameterscombination was achieved through range analysis of orthogonal test results, and thecombination was wind temperature120℃, wind speed2.6m/s,foming load7.9kg/m2.(4)Modified Page model can describe drying curves of crushed cotton stalks well andpredict moisture change in the drying process of crushed cotton stalks. Thus this model haspractical application value. Through regression, n=0.96and the relationship between k andT,V,W is k=0.0018T+0.0213V-0.0006W-0.0038M+0.0068(5)Crushed cotton stalks drying kiln was design and mainly inclulding the design ofoverall structure of kiln, kiln car and the selection of hot-air stove. The size of drying chamberis4.2m×3.4m×2.5m, and the size of drying kiln is5.75m×4.1m×2.95m. During onedrying process, the lowest fresh air quality is1386kg and the lowest heat is985084kJ. Thetype of the hot-air stove is small vertical level grate hand-burning stove, and abandoned cropstraw, abandon sawdust are used as fuel. Besides, direct fuel gas is used to provide hot air, inorder to improve the utilization rate of heat resource.