【作者】 朱新华；

【导师】 杨中平；

【作者基本信息】 西北农林科技大学 ， 农产品加工及贮藏工程， 2011， 硕士

【摘要】 玉米秸秆占我国农作物秸秆的27.39%,占我国农作物秸秆可收集资源的46%,但综合利用率较低,尚处在低效利用阶段,大多数玉米秸秆只是被简单地处理和利用。玉米秸秆的叶和髓含有丰富的营养成分,适于肥料化或饲料化利用,而玉米秸秆皮含有丰富的纤维素、半纤维素和木质素,适于能源化或秸秆代木化利用。只有将玉米秸秆叶、皮和髓进行分离,才能达到高效利用的目的。玉米秸秆的茎叶分离是其综合高效利用的关键技术之一选取郑单958、陕单136和沈单16三个品种的鲜玉米秸秆为研究对象,研究了品种、叶位、含水率对玉米秸秆茎叶结合强度的影响；研究了玉米秸秆在不同压扁厚度下其茎叶结合强度的变化规律和压扁对玉米秸秆节位处结构的破坏。在此基础上提出一种玉米秸秆茎叶分离方法——“压扁碾搓法”。根据“压扁碾搓法”的原理,设计并研制出一种玉米秸秆茎叶分离试验机。通过玉米秸秆茎叶分离试验,对茎叶分离机进行了参数优化和分离效果评价。研究得到以下结论：(1)秸秆品种间茎叶结合强度差异不大。三个品种的秸秆最大茎叶结合强度出现的节位有所不同,但都集中在雌穗穗位上下。三个品种的最大茎叶结合强度差异较小,在10.1 N/mm到10.3 N/mm之间。节位对茎叶结合强度的影响较为明显。各品种茎叶结合强度总体上由下到上依次增大,到雌穗穗位或其上一节达到最大值,此后下降。(2)随着含水率的降低,秸秆最大茎叶结合强度明显减小。未干燥时沈单16的含水率为82.56%,其最大茎叶结合强度为10.15N/mm。经80℃干燥12h后,含水率降至55.26%,其最大茎叶结合强度降至2.67N/mm。最大茎叶结合强度降至未干燥试样的26.3%。比较茎秆含水率和叶鞘含水率分别对茎叶结合强度的影响发现,叶鞘含水率与茎叶结合强度随节位的变化趋势具有一致性。(3)压扁可明显减小玉米秸秆茎叶结合强度。压扁程度越大,茎叶结合强度越小。不压扁时的茎叶结合强度最大。当含水率为17%左右,将秸秆分别压扁至4 mm、6 mm、8mm和10mm,其平均茎叶结合强度分别减小到未压扁时的9.2%、24.9%、35.9%和90.8%。考虑到压扁程度越大能耗越大,沈单16玉米秸秆的合理压扁厚度取为8mm。(4)样品经压扁后,所有样品的叶鞘与茎秆连接处,叶鞘均出现不同程度的横向断裂,且压扁程度越大,叶鞘横向断裂越严重。这证明压扁可显著降低茎叶结合强度。(5)设计研制的玉米秸秆茎叶分离试验机的试验参数调整灵活,能满足茎叶分离试验。选用含水率为21.68%的中科11号玉米秸秆进行茎叶分离正交试验,结果表明,秸秆茎叶分离影响因素的主次顺序依次是压辊间隙、剥辊速比和压辊转速。玉米秸秆茎叶分离的优选方案为：压辊转速200r/min,压辊间隙8mm,剥辊速比1.6,在此条件下,试验机剥叶率达到92.9%。(6)用“压扁碾搓法”对玉米秸秆进行茎叶分离具有理想的分离效果；研制的玉米秸秆茎叶分离试验机具有良好的试验性能。该研究为玉米秸秆茎叶分离开辟了新途径,为玉米秸秆高效综合利用奠定了基础。更多还原

【Abstract】 Corn straw accounts for 27.39% of crop straw resources and accounts for 46% of collectable crop straw resources in our country, but its utilization is still inefficient and most corn straws are only treated with simple methods. The leaves and stem piths of corn straw, containing abundant nutritional ingredients, are suitable for fertilizer or fodder. However, the stem barks, containing abundant cellulose, hemicelluloses and lignin, are suitable for biofuel or substitute of wood. How to separate leaves, stem piths and stem barks from corm straw is prerequisite for efficient utilization of corn straw. So, stem-leaf separation is one of key technologies to employ corn straw more efficiently.Three varieties of fresh corn straw, Zhendan958, Shandanl36 and Shendanl6, were used as experiment materials in the study. The influences of variety, node and water content of samples on stem-leaf bond intensity were studied. The change regularity of stem-leaf bond intensity of corn straw with flattened thickness and the structure breakdown caused by flattening were researched. On the basis of above experiments, a kind of new method for stem-leaf separation, named as "flatten-robbed method", was put forward. According to the method, a machine for stem-leaf separation test was designed and produced. By Orthogonal experiment of stem-leaf separation with the test machine, the parameters of separation machine were optimized and separation effect was evaluated. The conclusions are as follows:(1) The differences of stem-leaf bond intensity among three straw varieties were small, within 10.1N/mm-10.3 N/mm. Though the node position in which the stem-leaf bond intensity is maximal was different, the maximum stem-leaf bond intensity of the three straw varieties all were founded in about ear position of corn. Node position had a prominent influence on the stem-leaf bond intensity. Generally, the stem-leaf bond intensitys increased in order with the node positions from root to ear position, where the bond intensity reached maximum, and then decreased in order.(2) Reducing of water content cut down the maximum of bond intensitys evidently. The maximal bond intensity of Shendan 16 corn straw, with a water content of 82.56%, was 10.15 N/mm before drying, then dropped to 2.67 N/mm when the water content reduced to 55.26% when dried 12 hours at 80℃. So the maximum of bond intensity reduced to 26.3% of sample that not be dried. Meanwhile, by comparing the influences of water content of stem with leaf sheath, it could be founded that stem-leaf bond intensitys and water contents of leaf sheath had same change trend with node position.(3) Flattening decreased stem-leaf bond intensity of corn straw obviously. The smaller the thickness flattened, the bigger the decreased stem-leaf bond intensity. The stem-leaf bond intensity had maximum when corn straw wasn’t flattened. When corn straws with a water content of about 17% were pressed to 4mm,6mm and 8mm separately, the average stem-leaf bond intensity decreased to 9.2%,24.9% and 35.9% of original value correspondingly. Considering energy consumption during flattening,8mm of the optimal flattening thickness for corn straw should be used for Shendan 16.(4) Transverse cracks with different degrees were found at the node position where leaf sheath joins stem after the samples were flattened. Moreover, the smaller the flattened thickness of corn straw, the bigger the transverse crack in the leaf sheath. That indicates flattening of corn straw can reduce stem-leaf bond intensity evidently.(5) The designed stem-leaf separation test machine has adjustable parameters and can completely meet the demands of stem-leaf separation test. Orthogonal experiment of stem-leaf separation was conducted by selecting corn straw of Zhongke 11 variety with a water content of 21.68%. The results show that the sequence of factors effectiveness was: gap between press rollers, linear speed ratio between separation rollers and rotate speed of press rollers. The optimal scheme for stem-leaf separation of corn straw was:rotate speed of press rollers,200r/min; gap between press rollers,8mm; linear speed ratio between separation rollers,1.6. Under this condition, the separation rate was 92.9%.(6) "Flattening-robbed method" achieved good results for stem-leaf separation of corn straw. The test machine for stem-leaf separation of corn straw had good performance. This research offers a new way for stem-leaf separation of corn straw and laid a good foundation for efficient utilization of corn straw.更多还原