内返料内分级喷浆造粒干燥机返料流量研究

研究内返料内分级喷浆造粒于燥机的返料流量．通过分析粉料与螺旋通道进料口的相对运动揭示粉料进入螺旋通道的机理．利用积分法建立了返料流量的计算模型．返料流量等于螺旋通道进料口在单位时间内平均穿越的料层体积与有效返料系数之积讨论了有效返料系数的控制变量及其受装载系数的影响．     

内返料内分级喷浆造粒干燥机的分级效率模型

揭示了内返料内分级喷浆造粒干燥机的分级机理──速度梯度分级．建立了分级效率的数学模型，提出了分级效率的2个独立控制变量，指出了提高分级效率的途径和在锥小端增设筒筛的必要性．     

内返料内分级喷浆造粒干燥机的返料分级机理研究 Ⅳ.内分级技术

本文研究内返料内分级喷浆造粒干燥机的内分级效率。通过数学推导和理论分析，获得了内分组的最高分级效率和最低分级效率的计算模型。拟合实验数据得到内分级实际分级效率的关联式。讨论了返料倍数和粒度偏析对内级效率的影响情况，并提出相应的对策。     

内返料喷浆造粒干燥机分级返料研究

设计磷铵用全内返料喷浆造粒干燥机的关键是返料螺旋的确定,返料的前提是颗粒在回转圆筒内充分有效的分级。本文通过理论分析与简单的几何变换得到了返料螺旋口高度的计算公式,实验验证并得到修正系数。该公式为返料螺旋的确定提供依据     

内返料内分级喷浆造粒干燥机分级质量的影响因素及故障分析

本文指出了影响分级质量的因素,提出诊断分级故障的方法。     

内返料内分级喷浆造粒干燥机的返料分级机理研究 Ⅵ.悬浮式螺旋进…

本文研究内返料内分级喷浆造粒干燥机中悬浮式螺旋进料口的有效返料系数。推导出有效返料系数的计算式，讨论了螺旋进料口和悬浮高度、转筒半径和装载系数对有效返流系数的影响。     

内返料内分级喷浆造粒干燥机的返料分级机理研究Ⅴ．料幕分析

本文研究内返料内分级喷浆造粒干燥机的料幕特性。推导料幕密度的计算式和抄板最大撒料角的计算式，并认为料幕密度与物料性质有关。分析径向倾斜抄板对料幕的影响，讨论抄板弯角的合理性。     

全内返料喷浆造粒干燥机研究进展

全内返料喷浆造粒干燥机是集喷浆、造粒、返料、分级、破碎于一体的高效设备,具有结构紧凑、单机生产能力大、单位能耗低、适应性强、工艺成熟等优点,在磷复肥等领域获得广泛应用。本文介绍了全内返料喷浆造粒干燥机研究进展及成果。     

穿流回转干燥器的开发与应用

介绍了穿流回转干燥器的基本结构、工作原理、操作参数的确定以及其用于干燥聚丙烯酰胺的主要参数和特点。     

Synthesis,spray granulation and plasma spray coating of lanthanum phosphate nanorods for thermal insulation coatings

Nanorods of lanthanum phosphate obtained by a wet chemical precipitation route were granulated to obtain sizes in the range of 10–15 µm by spray drying from aqueous slurry of 35 wt% solid loading and 2 wt% of PVA binder. The powders thus obtained displayed enhanced flowability and were plasma sprayed on to stainless steel substrates resulting in the formation of adherent coatings of 150–180 µm thickness. These coatings were characterized using electron microscopy, X-ray diffraction analysis and Raman spectroscopy. X-ray analysis indicated phase instability of LaPO₄ during plasma spraying resulting in the formation of oxy and polyphosphates of lanthanum (La₂P₄O₁₃ and La₃PO₇). However, post deposition heat treatment of coated samples at 1100 °C for 2 h resulted in the reversible formation of stoichiometric lanthanum orthophosphate (LaPO₄). Raman spectral analysis was used to confirm the phase structure of the coatings deposited at various plasma input powers. The coatings obtained were found to effectively lower the thermal conductivity of the substrates from ~24 W/mK to less than 19 W/mK (~10%) even at 200 °C.     

Highly swirling transient flows in spray dryers and consequent effect on modeling of particle deposition

Cotton turf and hotwire measurements were used to experimentally assess the highly swirling flow characteristics in a spray dryer fitted with a rotary disc atomizer. The numerical simulation captured key features of the flow field. Analysis revealed that rapid rotation of an atomizing disc tends to centrifugally split the central inlet jet. The flow field exhibited significant long time-scale transient behaviour. However, this centrifugally split jet resulted in a balanced upward recirculation region in the chamber as expected by the jet-feedback mechanism. Detailed analysis using a ‘transient air-steady particle’ approach revealed that this approach is applicable for such highly swirling transient flows as well. However, caution should be exercised when interpreting the deposition results, particularly in regions of low particle velocities. This is anticipated be an important consideration in future attempts to simulate the predominantly transient flows in spray dryers.     

Reply to the Comment by K. Jorgensen et al. to “Analysis of constant rate period of spray drying of slurry”

Previously developed model for spray drying of slurry droplets with high solid content (Liang, 2001) was revised to describe correctly a boundary condition on the outer surface of droplet on basis of the rate of liquid evaporation.     

Morphology and sintering behaviour of yttria stabilised zirconia (8-YSZ) powders synthesised by spray pyrolysis

This work is focused on the synthesis of nano-crystallised yttria stabilised zirconia (YSZ) powders by the spray pyrolysis method, the aim of the study being a better understanding of the influence of the spray pyrolysis parameters on the morphology of the produced powders. Spray pyrolysed powder consists of polycrystalline particles, which are spherical. Each particle consists of nanometric primary grains. The morphology of these polycrystalline particles was characterised by scanning electron microscopy (SEM), helium pycnometry, thermogravimetric analysis (TGA) and mass spectroscopy (MS), and the results are compared. Thus, particle size, particle size distribution and particle porosity were determined and correlated to the process parameters. Finally, by dilatometric measurements, sintering curves of pellets prepared from different sets of powders were analysed in regard of their morphologies. Two main conclusions could be deduced from these studies. Firstly, the process parameters influence both internal porosity and particle size distribution of the synthesised powders. Secondly, the morphologies of the spray pyrolysed nano-powders lead to particularly high sintering activities.     

Influence of yttrium doping on the structural,morphological and optical properties of nanostructured ZnO thin films grown by spray pyrolysis

This study reports on the deposition of highly transparent, n-type ZnO thin films on glass substrate at 450?°C using spray pyrolysis processing, with the simultaneous insertion of yttrium (Y) at different percentages (0, 2, 5, 7?at%) as a dopant. The effect of Y doping on the structure, morphology and optical properties of Y doped ZnO (ZnO:Y) was investigated for optoelectronic applications. The obtained thin films were characterized by means of X-ray diffraction, field-emission scanning electron microscopy (FESEM), UV–visible absorbance measurements, photoluminescence (PL) and cathodoluminescence (CL) spectroscopy. The as-prepared films exhibit well-defined hexagonal wurtzite structure grown along [002]. Field emission scanning electron microscope micrographs of the pure ZnO and ZnO:Y showed that the films acquired a dominance of hexagonal-like grains, the morphology was influenced by Y incorporation. All the films showed high transparency in the visible domain with an average transmittance of 83%. The band gap energy, E_g, increased from 3.12?eV to 3.18?eV by increasing the Y doping concentration up to 5?at% and then decreased to 3.15?eV for 7?at% Y content. The PL and CL measurements reveal a strong ultraviolet (UV) emission, suggesting that the as-prepared ZnO:Y thin films can potentially be used in optoelectronic devices.     

Effect of precursor concentration on structural,morphological and opto-electric properties of ZnO thin films prepared by spray pyrolysis

Sprayed ZnO films were grown on glass substrate at 400 °C using zinc chloride as precursor with different molar concentrations varying from 0.05 to 0.2 M. X-ray diffraction patterns reveal that ZnO films are polycrystalline with hexagonal wurtzite structure with preferred orientation in (002) plane. Optical measurements show that transmittance reaches a maximum value of 95% in the visible region for ZnO films prepared from precursor with 0.05 M concentration. The films obtained from the precursor with 0.1 M concentration have the highest electrical conductivity and photocurrent values.