新型絮凝剂聚硫氯化铝用于处理双螺旋挤压法制浆废液的研究

介绍了采用酸析絮凝、聚合氯化铝与聚丙烯酰胺(PAC-CPAM)絮凝、聚硫氯化铝与聚丙烯酰胺(PACS-CPAM)絮凝处理双螺旋挤压法制浆废液。实验发现,该废液不适合采用PAC-CPAM絮凝;采用酸析絮凝效果较好;采用PACS-CPAM絮凝效果最好,且CODCr的去除率可以达到58%。     

Reverse Screw Element(s) and Feed Composition Effects during Twin-Screw Extrusion of Rice Flour and Fish Muscle Blends

The influence of location and spacing of reverse screw element(s) on specific mechanical energy input and product attributes during twin-screw extrusion of rice flour and pink salmon blends was investigated. Incorporation of reverse screw element(s) increased specific mechanical energy, expansion ratio and water solubility index; but decreased bulk density and Warner-Bratzler shear stress. Opposite trend was observed with increasing fish content except for shear stress, which was little affected either for rice flour or its blends with 30% fish solids in the expansion ratio range 5 to 10. Linear relationships were found between shear stress and bulk density and between solubility index and specific mechanical energy.     

双螺杆挤压对菠萝蜜种子淀粉消化特性及血糖指数的影响

为探究双螺杆挤压对菠萝蜜种子淀粉(JFSS)的消化特性及血糖指数的影响,采用体外消化试验,考察了JFSS经挤压处理前后的消化性与消化动力学变化,并通过水解指数(HI)、血糖指数(GI),预测了菠萝蜜种子淀粉的餐后血糖水平(PPBS)。结果表明,双螺杆挤压增加了快速消化淀粉(RDS)与慢消化淀粉(SDS)含量,提高了平衡浓度(C_∞)、酶解速率(k)、水解指数(HI)、血糖指数(GI)和淀粉消化率,显著降低了抗性淀粉含量(RS)(P<0.05)。在低水分含量下,增加螺杆转速与机筒温度,RDS含量由47.85%增加到58.91%,且k、C_∞、HI、GI值也均呈现增加趋势,而SDS含量、RS含量呈降低趋势。螺杆挤压使菠萝蜜种子淀粉由致密结构转变为疏松多孔的多面体结构。     

大豆分离蛋白双螺杆挤压组织化和流变性能的研究

分析了大豆分离蛋白在双螺杆挤压加工过程中流变性能,利用双螺杆挤出机的机头测试了大豆分离蛋白挤压过程中的表观粘度,得出随原料含水率、原料温度和螺杆转速的增加,大豆分离蛋白挤出过程中的表观粘度减小,并利用新型双螺杆挤压机进行了大豆分离蛋白组织化试验,获得大豆分离蛋白的组织化产品的光学显微照片和电镜显微照片,分析了大豆蛋白制品双螺杆挤压组织化机理。     

Monitoring the Diameter Changes of Flax Fibre Elements during Twin Screw Extrusion Using X-Ray Computed Micro-Tomography

ABSTRACT

Fiber size aspect ratio is known to impact the mechanical and reinforcement properties of natural fiber-based composites. However, the representation of fiber diameter change occurring during the extrusion process is controversial compared to the length. Fiber elements undergo multidirectional stresses and complex interactions within the extruder, leading to their breakage, which consequently may modulate their reinforcing properties. To better understand these mechanisms, short fiber reinforced polymer composites were prepared from flax fibers and polypropylene matrix (PP) by melt mixing. Five sampling zones were selected along the screws, both in screw conveying elements and inside blocks of kneading discs. X-ray computed micro-tomography, and 3D images analysis were then used for monitoring sample diameter distributions along the screw profile, according to specific twin-screw compounding conditions. The effects of the considered processing condition on fiber bundle diameters decrease along the screw profile are quantified.     

螺杆挤压过程食品流动能力计算与综合修正

螺杆挤压推料是食品加工过程中完成食品的输送、挤压与混合的常用工序,确定螺杆挤压过程食品流动能力,是为研究食品加工工艺及设备提供必要的条件。本文针对具有幂律非牛顿流体特性的一类食品,对前人的螺杆挤压流动模型及公式进行了简化与扩展,并提出了一种模型修正法--综合系数修正法。     

GC-IMS评价双螺杆挤压处理对香菇柄挥发性成分的影响

本文以香菇柄为研究对象,采用气相离子色谱技术分析在不同加水量(20%、50%)条件下经双螺杆挤压膨化处理香菇柄的挥发性成分的变化。结果表明,实验共检测并定性了醇、酯、醛、酮、呋喃类、含硫化合物6大类共35种挥发性物质。香菇柄在120℃加20%水的条件下经双螺杆挤压处理后,主要特征风味成分含硫化合物二甲基二硫醚相对百分含量从2.67%增加至3.62%。增加含水量至50%进行双螺挤压,二甲基二硫醚含量进一步增至6.66%;但对于1-辛烯-3-醇影响不显著。利用ROAV及主成分得分分析确定了1-辛烯-3-醇、芳樟醇、正己酸乙酯、丙酸乙酯、正辛醛、3-甲基丁醛、庚醛-M、异丁醛、丁醛、2-正戊基呋喃、二甲基二硫共11种物质为主要香味贡献成分,且感官评价与主成分得分分析显示在120℃加水20%条件下进行双螺杆挤压得分更高,可以增加挥发性风味成分的释放,改善风味。     

PP熔体在非啮合双螺杆挤出机中流动的数值模拟

利用ANSYS有限元分析软件对PP熔体在双螺杆挤出机非啮合并列型螺纹元件中的流动进行了三维非等温非牛顿流场分析,求出了速度场、压力场、温度场的基本规律以及螺杆特性曲线的分布。计算结果对实际生产具有一定的指导意义。     

基于ANSYS的双螺杆磨浆机传动系统主轴的有限元分析

在分析双螺杆磨浆机传动系统主轴系统且计算出系统所受载荷的基础上,利用有限元分析软件ANSYS完成传动系统主轴零部件静态有限元应力和应变分析,得到主轴零件在受载情况下的应力应变图,并对各种支撑情况进行了研究,提出合理的径向轴承布置方案。     

Shear Conversion of Corn Meal by Reverse Screw Elements during Twin-Screw Extrusion at Low Temperatures

Corn meal was extruded in a twin-screw extruder to study effects of one and two reverse-screw elements on conversion at extrusion temperatures > 60°C. Significant conversion was observed across the reverse-screw elements. The conversion was due to shear alone, since thermal effect was negligible at these low temperatures. Encompassing the reverse-screw elements were four visually distinct zones characterized by the state of the material.     

双螺杆磨浆机螺纹参数设计与研究

双螺杆磨浆机是一种同向旋转、啮合型磨浆专用的双螺杆挤出机。根据相对运动原理得到的双螺杆磨浆机的螺纹曲线比较复杂,不利于加工制造。本课题采用逼近方法将双螺杆的螺纹曲线简化成梯形,然后通过双螺杆间物料流量计算对螺棱顶宽的作用进行了分析,提出螺棱顶宽的选择范围;讨论了变螺距螺杆体积压缩比的计算方法。对双螺杆磨浆机螺纹曲线的简化不仅可满足双螺杆的啮合作用,保证生产效率,而且有利于螺纹的切削加工。     

电磁动态双螺杆挤出机的研制

在前人对混沌混合机理研究的基础上 ,将振动力场引入到平行异向双螺杆挤出机中 ,研制成功新型机筒剖分式电磁动态双螺杆挤出机实验样机。该机成功地将混沌混合引入到双螺杆 C型室螺槽之中 ,并能进行静态可视化实验研究。扫描电镜分析表征实验研究表明了振动力场有效地强化了体系的分布、分散混合效果     

双螺杆挤出机流道流场和操作参数的数值模拟研究进展

双螺杆挤压膨化技术是一种先进的物料挤压成型技术,在聚合物和食品加工领域有着广泛的应用前景。研究物料在流道内挤出流动状态和特性,对改进双螺杆挤出机的几何结构和操作参数有重要意义。本文围绕双螺杆挤出机流道仿真模型适用性分析、螺杆几何结构数值模拟和操作参数仿真分析等内容梳理了流场仿真结果,重点分析了影响流道内流动状态的因素。并对进一步优化数值模拟算法、建立品质指标关系和实现可视化研究方面提出了挤压机未来研究的建议,为更好的控制挤压过程、预测挤压结果提供借鉴和参考。     

双螺杆磨浆机螺纹参数的研究

根据同向旋转双螺杆共轭啮合原理得到的螺纹截面曲线比较复杂,不利于加工制造。首先通过逼近的方法将双螺杆的螺纹曲线简化成梯形,然后通过螺杆间物料流量计算对梯形螺杆螺棱顶宽的选取进行了分析,提出螺棱顶宽的选择范围,这样不仅保证了双螺杆的啮合作用,而且有利于切削加工。本文的工作对于双螺杆磨浆机的研究和设计具有重要的意义。     

双螺杆磨浆机构设计理论研究

双螺杆磨浆机是一种新型的高浓磨浆设备,具有磨浆质量好、节能节水等优良特性.在塑料工业同向旋转双螺杆挤出机设计理沦和方法的基础上,根据磨浆机理.系统研究了双螺杆磨浆机设计的理论和方法,包括双螺杆席浆机构设计流程、正向螺旋设计、反向螺旋设计和双螺杆磨浆机构的结构设计等.其中,双螺杆磨浆机螺纹深度、中心距、螺杆转速等参数的选择,间隙设计等方面参照同向旋转双螺杆挤出机的有关理论;螺纹导程、螺棱顶宽的选择,螺槽曲线的简化,反向螺旋设计和结构设计等方面采用新的理论和方法.最后通过实例说明了卜述设计珊沦和办法的应用.     

Effect of Extrusion-Cooking on Potato Starch Using a Twin Screw French Extruder

Potato starch has been processed in a semi-industrial twin-screw French extruder (type BC 45, Creusot-Loire) by courtesy of the C.T.U. The influence of the temperature of extrusion and the moisture content of the starch prior to extrusion has been studied. The water soluble starch increases with increase of both the extrusion temperature and the moisture content of starch prior to extrusion. In contrast, the aqueous ethanol-soluble carbohydrate fraction with DP < 14 increases with the temperature of extrusion and the decrease of moisture content. The largest amount of soluble oligosaccharides (16%) has been obtained with a temperature of extrusion of 190°C and a moisture content of starch prior to extrusion of 23%.     

辊式磨浆机用于落叶松SCMP的应用试验

落叶松磺化化机浆在高得率（试样Ⅰ，得率81．6％）条件下，仍能获得较高的强度（裂断长在4km以上），可以满足箱纸板底层用浆和瓦楞原纸用浆的强度要求，也可用作高强度纸和板纸的配浆。在双螺旋辊磨浆机磨浆过程中可进行浆料洗涤，洗涤用水减少，磨浆能耗一般低于200kWh/t浆。     

浆纱工艺中压出加重率的测试与计算

通过对高压上浆压出加重率、压浆力、浆液浓度、粘度等工艺指标的分析研究，提出了实际压出加重率的测试和计算方法，以确保压出加重率的准确性。     

Residence Time Distribution (RTD) in a Single Screw Extrusion of African Breadfruit Mixtures

Mixtures of African breadfruit (Treculia africana Decne), corn, and defatted soybean were extruded in a single-screw Brabender laboratory extruder at process variables derived from a second-order central composite design. The variables consisted of feed composition (0–100% breadfruit, 0–55% soybean, and 0 or 5% corn); fed moisture (15–27%), and screw speed (100–180 rpm). Effects of these variables on residence time distribution were investigated using Congo red as tracer. The extrudate spent longer time in the extruder as feed moisture or screw speed was decreased from 27% to 15% or 180 to 100 rpm, respectively, thereby increasing the residence time distribution characteristics. At 70% feed composition and screw speed of 140 rpm, mean residence time ([`(t)]\overline t ) increased from 40 to 50 s, whereas extrudate total collection time (t <sub>c</sub>) increased from 65 to 70 s. At screw speed of 100–180 rpm, mean residence time ([`(t)]\overline t ) decreased from 55 to 35 s, whereas extrudate total collection time (t _c) decreased from 75 to 65 s. At 100% African breadfruit composition, these time values decreased to 35 and 70 s, respectively, at the same screw speed, indicating the significant influence of feed composition and soybean addition to the mixture on residence time distribution. Residence time distribution curves indicated an early breakthrough time of 20 s at maximum screw speed (180 rpm), minimum tail of 65 s, and a plug flow pattern of the extrudates.