【作者】 郭贵生；

【导师】 郭康权； 吕新民；

【作者基本信息】 西北农林科技大学 ， 农业机械化工程， 2010， 博士

【摘要】 油菜籽壳(皮)中含有植酸、单宁、色素、芥子碱等有碍物质。传统的制油工艺采用带壳压榨,既降低油的质量、加重毛油色泽,造成精炼困难,也使菜籽饼粕的品质变差,影响进一步开发利用。所以油菜籽脱壳制油新工艺备受关注,其中,破壳(脱皮)、分选技术与设备的开发,成为新工艺的关键。本论文在研究了油菜籽基本物理力学特性的基础上,分析了油菜籽破壳的基本原理;设计试制了破壳机,并进行了破壳性能试验,分析了油菜籽含水率,转速等因素对破壳率、粉末率的影响;根据破壳油菜籽的物料组成及特性,分析了破壳油菜籽分选原理,设计试制了分选样机;采用二次正交旋转试验对影响分选机性能的因素进行了研究,得到了喂入量、前风道风速、后风道风速等因素与性能指标—壳中含仁率和仁中含壳率的关系。取得的主要研究结论如下:(1)白菜型、芥菜型和甘蓝型油菜籽的体积形状系数分别为0.493、0.468和0.513,接近0.5238球形的体积形状系数;三种油菜籽的粒径分布分别服从正态分布X～N(1.49,0.1483~2)、X～N(1.25,0.1483~2)和X～N(1.589,0.2417~2)。(2)单粒油菜籽在挤压过程的受力与变形关系具有明显的双峰特征,且第一次峰值具有脆性物料的特性;随着油菜籽粒径的增加,两个屈服点和破裂点的力值增加;随着油菜籽含水率的增加,屈服点的力值减小,第一屈服点的变形量减小,第二变屈服点的变形量增加;随着变形加载速度的增加,屈服点的力值增加。(3)随着油菜籽粒径增加,剪切力增加而剪切强度减小;随着含水率的增加,剪切力和剪切强度均减小;随着剪切速度的增加,剪切力和剪切强度均增加。(4)两次撞击的油菜籽破壳方法,能够实现对油菜籽进行破壳加工,其脱壳率大于75%,粉末率小于5%。(5)给出了油菜籽颗粒在离心甩盘加速作用下的运动学及动力学方程;提出了油菜籽破裂所需功为弹性变形和塑性变形所需功之和,得出了油菜籽破壳所需功的计算方程。(6)随着油菜籽含水率的增加,破壳率和粉末率均降低;随着破壳机喂入量的增加,破壳率和粉末率减少。(7)增加破壳机离心甩盘的转速,能增大破壳率,同时粉未率也增大,壳、仁分选的难度增加。(8)在破壳机离心甩盘下方安装复脱打板,能提高脱壳机的脱壳性能,但打板数量不应太多,应以两个为宜;复脱打板安装位置和高度最佳值分别为:15cm、5cm。(9)依据利用气流、振动和筛选相结合的原理设计了破壳油菜籽分选机,采用筛面前后段筛孔直径不等的方法,能够对破壳油菜籽进行有效分选。(10)给出了破壳油菜籽分选机的喂入量、前吸风道和后风道风速对分选性能指标影响的回归方程;影响壳中含仁率的主次因素为:前吸风道风速、后吸风道风速、喂入量;影响仁中含壳率的主次因素为:前风道风速、喂入量、后风道风速。(11)破壳油菜籽分选机操作参数的最佳组合为:喂入量:650～750kg/h、前风道风速:1.5m/s、后风道风速:5.14m/s。(12)喂入量、前风道风速、后风道风速对壳中含仁率和仁中含壳率的影响存在交互作用,特别是后风道风速与前两者的交互作用明显。本论文的创新之处:(1)提出了两次撞击的油菜籽破壳原理;(2)提出利用气流,振动和筛选相结合的破壳油菜籽分选原理,且筛面采用前后段筛孔直径不同的方法能有效的对破壳油菜籽进行分选;(3)提出了油菜籽破裂所需的功计算方法;(4)建立了喂入量、前吸风道和后风道风速和壳中含仁率、仁中含壳率的回归模型。更多还原

【Abstract】 The hull of rapeseed contains some adverse substance, such as phytic acid, tannin, pigment, sinapine and so on. The traditional method of making oil from rapeseed does not remove the hull of rapeseed, which not only decreases the quality of oil, enhances the color of semi-finished oil ,results in difficulties in refining,but also decreases the quality of rapeseed cakes so that affect its further development and utilization. Therefore, new techniques of hulling and oil manufacture have been concerned, and the equipment development of hull broken and separation technology becomes the key.Basing on the study of the basic physical and mechanical properties of rapeseed, theories of rapeseed hull broken was analyzed.Design and trial-manufacture of rapeseed hull-broken machine were carried out, and hull-broken machine performance experiments was made. It was analyzed that the rate of hull broken and the rate of powder were influenced by rapeseed moisture content, rotating speed and other factors. According to the material composition and property of hull broken rapeseed, the separation principle of hull broken rapeseed and the main structural parameters were analyzed; a kind of hull broken rapeseed separator was designed. Analyzed the factors that affect the performance of separating machines in the method of quadratic orthogonal rotary experiment. The relationship between factors-such as feeding volume, wind speed of front wind tunnel as well as wind speed of behind wind tunnel and the performance index- the rate of hull including kernel and the rate of kernel including hull-were concluded.Conclusions are as follows:(1) Volume shape coefficients of rapeseed for cabbage type,leaf mustard type and wild cabbage type were 0.493,0.468 and 0.513. It respectively close to the spherical volume shape coefficient 0.5238,the granular diameter of rapeseed for cabbage type, leaf mustard type and wild cabbage type obeys to the normal distribution: X~ (1.49,0.14832), X~ (1.25,0.14832) and X~ (1.589,0.24172).(2) The relationship between extrusion force and deformation for single grain rapeseed is an obvious double-peak feature in the compression process, and the first peak has the characteristics of brittle materials. As increase of rapeseed granular diameter, the force value of the two yield point and rupture point was increased .With the increase in moisture content of rapeseed, the force of yield point was decreased, the deformation value of the first yield point was decreased; the deformation value of the second yield point was increased. Along with increase of deformation loading velocity, distortion shearing force and shearing strength were increased.(3) With the increase of rapeseed granular diameter, the shearing force is increased and shearing strength is decreased. With the increase in moisture content, both of shearing force and shearing strength are decreased. With the increase in shear velocity, shearing force and shearing strength are increased.(4) The method of rapeseed hull broken by the twice striking can achieve to break the rapeseed hull. The rate of hull broken is more than 75%, and the rate of powder is less than 5%.(5) The rapeseed grain’s kinematics and dynamics equations in acceleration of centrifugal throwing dish have been given. It was proposed that the necessary power for rapeseed breakage is the power of elastic deformation and plastic deformation. The computational equation of the power for rapeseed hull broken was obtained.(6)With the increase in the moisture content of rapeseed, the rate of hull broken and rate of powder decreases .With the increase in feeding volume of hull broken machine for rapeseed, the rate of hull broken and rate of powder decreases also.(7) With the increase of centrifugal throwing dish speed, the rate of hull broken and rate of power were increased. Meanwhile, the difficulty in separation kernel and hull also was increased. (8) Assembling re-threshing boards under the centrifugal throwing dish can improve the performance of hull-broken machine, but the number of the board should not be more than two. The location and height of the best values of re-threshing boards are: 15cm, 5cm.(9) Based on the principle which combines the air current, vibration and screening, the separator of hull broken rapeseed was designed. Hull broken rapeseed can be effectively separated by using different mesh in anterior and posterior of sieve.(10)Regression equations that feeding volume,wind speed of front wind tunnel and that of behind wind tunnel influence performance index of separator were given. The sequences of factors, influencing the rate of hull including kernel, are wind speed of front wind tunnel, wind speed of behind wind tunnel and feeding volume. The sequences of factors, influencing the rate of kernel including hull, are wind speed of front wind tunnel, feeding volume and wind speed of behind wind tunnel. (11) The best combination of operating parameters for separator of hull broken rapeseed are as follows: feeding volume: 650～750kg/h, wind speed of front wind tunnel: 1.5m/s, wind speed of behind wind tunnel: 5.14m/s.(12) It have correlation that the rate of hull including kernel and the rate of kernel including hull were influenced by feeding volume, wind speed of front wind tunnel and wind speed of behind wind tunnel. Particularly, wind speed of behind wind tunnel and the other two factors have obvious correlation.The innovations of this thesis are as follows:(1) Based on the twice striking method, the principle of rapeseed hull broken was proposed;(2) The separation principle of combination of air, vibration, and screening for rapeseed of hull broken was proposed. Hull broken rapeseed can be effectively separated by using different mesh in anterior and posterior of sieve;(3) The computational method of power for the rapeseed hull broken was proposed;(4) The regression model which the rate of hull in including kernel,the rate of kernel including hull were influenced by feeding volume, wind speed of front wind tunnel as well as wind speed of behind wind tunnel was established.更多还原