Inter-tablet coating variability: Tablet residence time variability

This paper investigates inter-tablet coating variability, specifically, the variability of tablet residence times within the spray zone of a horizontal coating pan. Results from experiments, discrete element method (DEM) computer simulations, and an analytical model developed to describe the coating mass distribution are presented.The simulations indicate that the coefficient of variation of tablet residence times, and subsequently, of coating mass, decreases with time following a power law relation. The theoretical model demonstrates that the coefficient of variation of residence time for a randomly mixed tablet bed is inversely proportional to the square root of the number of coating “trials”. DEM simulations show that during each pan revolution, tablets in the spray zone remain in a quasi-segregated state from tablets located outside the spray zone for some time period termed Δt_seg. Increasing the pan's Froude number, the spray zone aspect ratio, and the tablet-tablet and tablet-pan friction coefficient all act to decrease Δt_seg, leading to more uniform residence times and less inter-tablet coating variability for a given operating time. The relationship between Δt_seg and tablet load is more complex due changes in bed dynamics. In addition to the variability studies, a model is developed that relates coating fraction, effective mass flow rate, Δt_seg, and the desired coating mass to the allowable fraction of tablets with a coating mass lying outside of a specified range of coating masses.     

混合机减速器高速轴承结构的改进

本文就圆筒混合机械减速器高速小弧齿锥齿的轮经常的断的原因进行了分析，同时地减速器的高速轴承的安装结构进行了改进，弥补了混合机减速器存在的设计缺陷，保证了上料线设备的稳定、顺行。     

滤棒动态发射原理与结构开发

卷烟企业的烟机生产速度和自动化程度越来越高,其辅料的用量也越来越大,因此急需滤棒自动供料系统。滤棒动态发射基本原理是依靠压力差推动滤棒运动,根据该原理开发出的滤棒发射接收装置,其核心部分为发射单元,主要组成部分为阻挡辊、发射鼓、密封靴。阻挡辊用于向发射鼓的鼓槽内均匀地输入滤棒,发射鼓连续运转保证每根滤棒间隔一定的距离发射,密封靴通过上下运动来控制滤棒发射过程。该装置已广泛应用到卷烟企业,满足了卷烟企业需求。     

Numerical Study of Heat Transfer and Fluid Flow in Multiple turbulent Impinging Jets

ABSTRACT

Impingement flows have been studied extensively for various geometries and configurations, but because of the complexity of the turbulent flow and its strong dependence on the geometry of the flow, further investigation is required to identify the suitable model for specific cases. This paper presents a study of various k–E turbulence models in order to identify the best model for an array of multiple confined impinging slot jets, with exhaust ports in the confinement surface located symmetrically between adjacent jets. Such a configuration is used in a novel drum dryer for black liquor. The “High Reynolds number” turbulence models including the standard k–E model fail to predict heat transfer to impingement surface accurately although they do predict the flow field reasonably well. On the other hand, the “Low Reynolds number” models yield considerably better results for both fluid flow and heat transfer. All computed results are compared with experimental data reponed in the literature. This work was motivated by the need to select an optimal multiple impinging jet configuration for a novel drum dryer for Kraft black liquor. It is also pertinent to impingement dryers for paper, films, textiles etc.     

碳酸钙鼓式过滤机试车小结

总结了碳酸钙鼓式过滤机在生产能力、洗涤效果等方面的情况，并与原带式过滤机作了比较。     

The flowability of fine powders in reduced gravity conditions

The extrapolation of Qian’s semi-theoretical relationship for the transition between cohesive and non-cohesive powder fluidization behavior into regions of low gravity is studied and a validation experiment employing fluidization is discussed. The fluidization experiment utilized fine glass and alumina powders in a fluidized bed and was flown onboard NASA’s reduced gravity aircraft. The transition region between cohesive and non-cohesive behavior is determined for the glass and alumina powders at gravity levels of 1.8, 1.0, 0.38, and 0.16 g. The results are compared to Qian’s model and show fair agreement. The fluidization experiment limitations are discussed and a rotating drum experiment that will reduce the experiment uncertainty, provide quantifiable results, and is suitable for flight onboard NASA’s reduced gravity aircraft is proposed. The rotating drum technique determines the characteristic frequency of the powder’s center of area to detect avalanching. The concept is validated by comparing the characteristic frequency obtained from analyzing a cohesive powder to the characteristic frequency obtained from analyzing a flowable powder.     

锅炉汽包开孔内壁处裂纹分析和修复

根据宏观检查、化学分析、金相检验、裂纹形貌和裂纹成因分析，认为锅炉汽包在开孔内壁处产生方的主要原因是由于锅炉进水口供水温度过低，过泠水从进水管冲入汽包，碰撞到档水板引起过冷水飞溅到汽包开孔内壁处使该处产生温差应力而导致裂纹，提出了增加防护板或改进进水方式等有效的修复方法和预防措施。     

温压法制备鼓式制动摩擦材料

采用腰果壳油三聚氰胺改性液体酚醛树脂做黏合剂、腈纶短纤维和复合型摩擦粒作为增强材料,温压工艺制备的鼓式制动摩擦材料,具有良好的摩擦磨损性能、适中的孔隙率及良好的冲击强度和弯曲性能.研究了模压温度、成型压力、保压时间等工艺参数对材料性能的影响,为具有一定孔隙率的鼓式片的工业化生产提供实验依据.     

Improved Peanut Flour for a Reduced-Fat Peanut Butter Product

A commercial peanut flour (12% fat) was mixed with water (30% w/w), homogenized and drum‐dried in a double drum dryer. The drum clearance was adjusted to result in thin dried sheets which on milling resulted in a very fine, single banded particle size flour. The flour was no longer gritty and was used to dilute fat by mixing with full fat (52.5%) paste to obtain a 30% fat reduction in the peanut butter product. Response surface methodology, RSM, was used to optimize drum temperature (T), speed (S), and clearance (C) in order to minimize stickiness and hardness, maximizing oil separation and particle size. Based on surface responses and contour plots, optimum conditions were: T = 135 °C, S = 1 rpm and C = 0.33 mm. Optimum values predicted by RSM for peanut flour particle size, peanut butter stickiness, hardness, and oil separation were: 49.65 μm, 12347 N, 311.4 N and 6.87% respectively. Close agreement between experimental and predicted values was obtained.     

槽筒数字化设计与制造方法的研究及应用

槽筒是自动络筒机上用于卷绕成形的关键零件.该薄壁回转体上的导纱线槽形状复杂,制造要求高.开展数字化槽筒设计与制造方法的研究和实践,是实现高档次络筒机国际竞争力的主要途径之一.文章就槽筒导线槽设计、加工工艺、定位夹紧方案及数控编程进行了研究和实践,取得了较为理想的效果.