【作者】 刘峰；

【导师】 任奕林；

【作者基本信息】 华中农业大学 ， 现代农业装备工程， 2016， 硕士

【摘要】 传统肥料存在着适应面窄,肥料颗粒特性不能满足特定需求,施用后对土壤有污染等问题,这就要求大力发展符合现代农业需求的新型肥料。生物炭施入土地后可吸附养分提高肥力,实现作物增产的效果,近些年被越来越多的应用到农业中。本文旨在研究新型生物炭颗粒肥的成型条件、挤出滚圆成型装置和造粒工艺优化,为新型生物炭颗粒肥的制作工艺和设备生产提供参考和指导。主要内容及结论如下:1)粉体物料及粘结剂的特性测试。检测了生物炭粉及膨润土等主要粉体的流动性、喷流性、含水率等特性和粘结剂的粘度特性。在低浓度混合粘结剂中,木质素磺酸钠:可溶性淀粉=1:2配比下粘度效果最好;在高浓度混合粘结剂中,阿拉伯树胶粉:海藻酸钠=1:1配比下粘度效果最好;最后确定后续试验采用粘结剂的配比为海藻酸钠:可溶性淀粉:木质素磺酸钠=1:6:3。2)生物炭颗粒肥挤出成型条件试验研究。以挤出成型装置为主要试验平台,分析影响试验的因素及水平并设计正交试验,得出最优方案为生物炭粉与膨润土的比例为1:4、下压速率为60mm/min、粘结剂的浓度为8%、粘结剂所占整体物料的百分比为40%,为后续的生物炭颗粒肥成型试验提供准确的指导。探究了挤出孔径和滚圆对生物炭颗粒肥特性的影响,得出增大孔径和滚圆对颗粒特性均有促进作用。3)挤出滚圆机的设计优化及制作。确定挤出滚圆造粒方式,并对选定方案进行成粒机理与运动分析,设计并试制了一种挤压滚圆一体机,主要包括挤出系统、切割机构、滚圆出料系统和电气系统等部分,生产能力为5 Kg/h,螺杆直径为55mm,长径比为4,根据更换不同孔径的孔板可生产1~5mm粒径的颗粒,可实现物料的挤出、自主剪切和滚圆出料。4)生物炭颗粒肥造粒工艺研究与试验。利用挤出滚圆造粒机进行生物炭颗粒肥成型试验,分别从单因素和正交造粒试验探索和优化生物炭颗粒肥成型工艺。通过对正交试验结果的直观分析和方差分析,最终得出最优方案为膨润土与生物炭的比例为2.2:1、挤出转速为8RPM、粘结剂的浓度为8%、粘结剂占总体粉料的30%。5)生物炭颗粒肥特性对比检测。根据正交试验最优方案进行造粒,把制得的生物炭颗粒肥与2种市场上使用其他造粒方式制得的生物炭基肥从多个方面进行颗粒特性对比。检测得知,3种颗粒肥的生物炭含量和营养成分含量的总和基本一致,使用挤出滚圆法制得的生物炭颗粒致密度较高,在含水率、颗粒抗压强度、圆度和粒度分布等指标上整体性能较好,在养分释放性能上属于中间水平,在吸湿性能上表现欠佳,在后期可考虑相应的后处理工艺进行改善。更多还原

【Abstract】 The traditional fertilizer has the characteristics of narrow adaptability and soil pollution, which can not meet some specific needs. That requires us to make significant efforts to develop new types of fertilizer so as to meet the needs of modern agricultural development.Biochar which can effectively make soil adsorb nutrient and improve fertility is increasingly applied to agriculture in recent years, so as to reach the aim of increasing production. The purpose of this paper is to research the shaping condition of innovative biochar granular fertilizer, shaping equipment of extrusion–spheronization and optimizing granulation process, moreover, provide reference and direction for fabrication process and manufacturing equipment of innovative biochar particle fertilizer. The following research works and conclusions were obtained:1) Feature detection of powder materiel and binder. Biochar powder and bentonite were understood through the feature detection as major powder materiel, so as to process powder materiel later. Viscosity properties of the binder were also detected. In the result, the best binder combination ratio in low concentration test was sodium lignin sulfonate: soluble starch=1:2; while in high concentration test was gum acacia: sodium alginate=1:1; it was determined that the proportion of the binder was sodium alginate: soluble starch: sodium lignin sulfonate =1:6:3 through comprehensive analysis.2) Experimental study on extrusive shaping condition of biochar granular fertilizer. The factors and levels which influence the experiment were analyzed by extrusive granulating device as the main testing equipment, besides, an orthogonal test was designed. After a comprehensive analysis of the test results, when the ratio of biochar powder and bentonite was 1:4, the compressed speed was 60mm/min and binder which concentration was 8% accounted for 40% of total material, the experimental effect was the best. It provides accurate guidance for the subsequent molding experiment of biochar granular fertilizer. After exploring the effect of extrusion aperture and spheronization on biochar fertilizer characteristics, it is concluded that increasing aperture and spheronization have a facilitating role on fertilizer characteristics.3) Design and manufacture of extrusion–spheronization machine. After determining the extrusion spheronization method, the particle principle and motion analysis of the selected scheme were analyzed. And then an extrusion spheronization granulator was designed and manufactured, which mainly including extrusion system, a cutting mechanism, spheronization system and electrical system, etc. The production capacity of 5 kg/h, screw diameter 55 mm and the ratio of length to diameter is 4. According to the replacement different aperture plates, the machine can produce 1 ~ 5mm size of the particles, while achieving material extrusion, automatic cut, rounded and automatic discharge.4) Research and experiment on granulation process of biochar granular fertilizer. Biochar granular fertilizer and molding experiments take the advantage of the extrusion spheronization granulator, exploring from the single factor and orthogonal experiments respectively in order to optimize the biochar granular fertilizer and molding process. After visual analysis and variance analysis of orthogonal test results, when the ratio of biochar powder and bentonite was 1:2.2, the extrusion speed was 8 RPM and binder which concentration was 8% accounted for 30% of total material, the experimental effect was the best.5) Feature comparison and detection on characteristics of biochar granular fertilizer. The author compared the characteristics from multiple aspects of particle between two fertilizers on the market that were made with biochar by other granulation process and the biochar granular fertilizer which was granulated according to the orthogonal test optimal scheme. Test results showed that the total biochar content and nutrient content of three particles biochar fertilizer were consistent. The biochar granular fertilizer had high tightness by means of extrusion spheronization; it has better performance in the following indicators: moisture content, compressive strength, roundness and granularity; it reached the median level on nutrient release performance; it performed poor on hygroscopicity, therefore, corresponding postprocessing should be considered to improve its hygroscopicity in later stage.更多还原