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空气助力改善气化炉激冷室喷嘴特性的实验研究 总被引:1,自引:0,他引:1
设计了4种不同结构的用于气化炉激冷室内喷雾激冷的压力雾化喷嘴,采用马尔文激光粒度分析仪和数码单反照相机分别测量了不同压差、不同水流量等工况参数下的液滴粒径(SMD)D32分布和雾化角变化规律,并对4种喷嘴进行了优化选型。研究结果表明:雾滴粒径随压力的增加而减小,随水流量的减小而减小,空气助力可以明显改善液滴的雾化质量;雾化角随压差的增大先增大后趋于平缓;当压差增大到0.4 MPa时,雾滴粒径、雾化角等参数的变化渐趋平缓。通过比较气化炉激冷室中4种压力式雾化喷嘴的测量结果,1-2号内混式空气雾化喷嘴在4组喷嘴中具有最好的雾化效果,当气压为0.8 MPa,水流量为20 L/h时,SMD极小值为16,因此优选出喷嘴1-2作为气化炉激冷室冷模实验的定型喷嘴。 相似文献
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本文从喷嘴的雾化机理出发,总结了压力式喷雾干燥器所用的离心式压力喷嘴的优缺点,研制了一种低压雾化、大流量喷嘴,并通过冷态喷水及热态喷浆试验,分别测定了其流量、雾化角及所得粉料的粒度级配,并与离心式压力喷嘴进行比较。认为如采用此喷嘴进行雾化,可以降低雾化压力以减小对泵及喷孔的磨损,而且所得的粉料其粗颗粒明显增多,细颗粒明显减少。 相似文献
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本通过采用新研制的低压雾化、大流量喷嘴及离心式压力喷嘴进行了冷态喷水、热态喷浆试验及工业生产应用试验,分别测定、比较了其流量、雾化角及所得粉料的粒度级配。认为工业生产上采用低压雾化、大流量喷嘴,可以降低雾化压力以减低对泵及喷片的磨损,而且所得的粉料其粗颗粒明显增多,细颗粒明显减少,利用节能。 相似文献
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针对喷嘴雾化多参数同步测量问题,提出了基于图像处理的喷嘴雾化角、雾化细度、液滴运动速度及分布参数测量方法,利用背光阴影成像技术搭建了喷嘴雾化参数测量系统,建立了基于轨迹图像法原理的喷嘴雾化参数图像处理流程与算法,利用标准颗粒测量验证了该方法对颗粒粒径测量的精度,并开展了不同孔径与压力下扇形喷嘴雾化参数同步测量实验研究。结果表明:当雾化压力不变,扇形喷嘴孔径从0.66 mm变为1.10 mm时,雾化细度与液滴平均运动速度分别增加26.82%、10.42%,而雾化角随扇形喷嘴孔径增大而减小16.66%;当扇形喷嘴孔径不变,雾化压力从0.1 MPa增加到0.4 MPa时,雾化角与液滴平均运动速度分别增加47.71%、95.10%,而雾化细度随雾化压力增加而减小44.23%。这为雾化液滴特性研究与喷嘴性能评估提供了有效手段。 相似文献
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喷嘴的结构对燃油锅炉、加热炉的燃烧效率有着至关重要的影响。为了进一步提高燃油锅炉、加热炉的燃烧效率,提出了一种内混式蒸汽雾化燃油喷嘴结构,介绍了内混式雾化喷嘴雾化工作原理。建立了内混式喷嘴物理模型,采用CFD软件对内混式喷嘴的流场进行了数值模拟,探讨了内混式喷嘴雾化室的长度、气液比对雾化粒径的影响规律;同时,对喷嘴下游不同截面的雾化粒径大小分布规律进行了研究;并将平均雾化粒径模拟结果与常规内混式喷嘴经验公式的计算结果进行了比较。研究结果表明:内混式喷嘴的混合室长度最佳值是70~80 mm;随着气液比的增大雾化粒径减小;液体燃料第二次雾化主要发生在燃料离开喷嘴100 mm之内;同时,研究结果表明新型的内混式喷嘴的雾化粒径小于常规的内混式喷嘴的雾化粒径。 相似文献
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对新型引射雾化喷嘴的流量系数、雾化角、雾粒分布均匀性进行了研究,提出了喷嘴流量系数、雾化角、雾粒大小计算方法。研究表明,这些方法的计算结果与实际很接近,对新型引射雾化喷嘴的设计计算十分有益,具有重要的工程意义。 相似文献
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利用离散相模型对转炉一次除尘新OG系统高效喷淋塔内喷嘴的雾化特性进行模拟,分析了喷射角度、喷射压力、喷射流量及喷嘴水平间距等因素对雾化场索太尔平均直径(SMD)和蒸发效率的影响. 结果表明,在一定范围内随喷射角度增加,液滴在雾化场中的覆盖面增大,液滴驻留时间变长,蒸发效率增加,雾化场SMD减小,喷射角度大于60o时,SMD值减小缓慢. 随喷射压力增大,液滴蒸发效率增加,雾化场SMD减小,压力大于1.0 MPa时对SMD的影响较小. 随喷射流量增加,液滴蒸发效率减小,雾化场SMD增加,流量小于0.15 kg/s时,SMD增加幅度偏小. 两喷嘴水平间距越大,液滴分布面积越大,但对雾化场SMD影响较小. 在一定条件下,喷嘴间距约为800 mm时,截面速度分布较均匀. 相似文献
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为改善重油雾化质量,针对沥青站重油燃烧器Y型喷嘴,运用CFD (Computational Fluid Dynamics)方法研究了喷嘴结构参数(混合室长度、入口直径比、入口夹角)与雾化参数(重油流量、空气入口压力、重油温度)对喷嘴气液两相流动与雾化特性的影响。结果表明,结构参数与雾化参数直接影响喷嘴内油膜厚度与气液两相速度差;不同参数下,喷嘴气耗率与液滴索泰尔平均直径的变化规律相反;综合考虑两个雾化性能指标,混合室的适宜长度为15~20 mm,入口夹角的合理范围为60°~75°,入口最佳直径比为1.0~1.1;为保证重油获得较好的雾化效果,空气入口压力应大于0.5 MPa,这为优化Y型雾化喷嘴的结构与运行参数提供了参考。 相似文献
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Xiaoning Mao Qinglong Xie Ying Duan Shangzhi Yu Xiaojiang Liang Zhenyu Wu Meizhen Lu Yong Nie 《中国化学工程学报》2020,28(4):1023-1028
Pyrolysis of methyl ricinoleate(MR) can produce undecylenic acid methyl ester and heptanal which are important chemicals. Atomization feeding favors the heat exchange in the pyrolysis process and hence increases the product yield. Herein, predictive models to characterize the atomization process were developed. The effect of spray distance on Sauter mean diameter(SMD) of atomized MR droplets was examined, with the optimal spray distance to be 40–50 mm. Temperature mainly affected the physical properties of feedstock, with smaller droplet size obtained at increasing temperature. In addition, pressure had significant influence on SMD and higher pressure resulted in smaller atomized droplets. Then, a model for SMD prediction, combining temperature, pressure, spray distance, and structural parameters of nozzle, was developed through dimensionless analysis. The results showed that SMD was a power function of Reynolds number(Re), Ohnesorge number(Oh), and the ratio of spray distance to diameter of swirl chamber in the nozzle(H/dsc), with the exponents of -1.6618,-1.3205 and 0.1038, respectively. The experimental measured SMD was in good agreement with the calculated values, with the error within ±15%. Moreover, the droplet size distribution was studied by establishing the relationship between the standard deviation of droplet size and SMD. This study could provide reference to the regulation and optimization of the atomization process in MR pyrolysis. 相似文献
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还原剂雾化质量对循环流化床锅炉旋风分离器SNCR脱硝效率具有重要影响,为研究空气雾化喷嘴结构参数对雾化质量及脱硝效率的影响,采用数值模拟的方法对喷嘴的4个结构参数即撞击件长度、出口直径、混合室长度和气液入口交角,进行单因素分析和正交数值试验,结果表明影响旋风分离器烟气脱硝效率的主要因素是喷嘴出口直径,次要因素是撞击件长... 相似文献
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综述了催化裂化进料喷嘴的作用及特点,详细介绍了喉管类、靶式类、气泡雾化类、旋流式类、三次雾化类、气动雾化和气泡雾化结合类等进料喷嘴的结构特点、雾化机理及雾化效果。进料喷嘴的发展方向是深入了解气液两相流理论和气液初始作用,以及喷雾场存在雾化不均匀性,进一步研究出口形式使雾化粒度合适,压降分配合理。 相似文献
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A study was made of a centrifugal pressure nozzle with large orifice diameter (8-10 nun) for producing dry milk in capacity of 2-3 tons per hour to develop some performance data on spray distribution, drop size distribution, and capacity with changing spray drying conditions such as nozzle pressure, orifice diameter and spray angle. Experimental results were shown as follows. (1) A centrifugal pressure nozzle of large capacity such as 5,000- 5,500 l/hr at 150 kg/cm2 spray pressure and 110°s ray angle was designed by using the nozzle parameter Si/dedi√di/di. (2) Atomization characteristics were greatly affected by the ratio of orifice diameter (de) to the length (L) of the nozzle core. The smaller the ratio, around 0.125, the better are the atomizing effects. (3) The large orifice can be used at least 3,000 hr in the spray drying operation for milk without any wear in the orifice although it is only made of stainless steel. As a result, a spray dryer of large capacity for dry milk has been operated by a mono nozzle with a large orifice without any trouble for a long time 相似文献
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Rolf D. Reitz 《Aerosol science and technology》2013,47(3):561-569
To gain an insight into the mechanisms of flash-boiling atomization, heated water was injected from a single-hole orifice into heated air (steady injections, liquid pressure 697 kPa, air pressure ambient, test temperatures from 300 to 426 K, orifice diameter 0.34 mm, length 1.37 mm). The breakup regime of interest in the study was that where the spray divergence starts at the nozzle exit. Short-duration backlit photographs and laser diffraction dropsize measurements showed that these flashing jets comprise an inner intact core which is surrounded by the diverging fine spray. These details about the spray structure are not visible in conventional photographs of flashing sprays that use scattered light illumination. The present results cast doubt on a previously proposed theory of flash-boiling atomization that attributes the divergence of the spray cone to the expansion processes that occur in an underex-panded compressible flow, since that theory implies that the liquid is already atomized upon leaving the nozzle. Instead, the photographs show that drops are expelled from the unbroken liquid jet starting at the nozzle exit (presumably by rapid vapor bubble growth within the jet). The core region remains intact for some distance downstream of the nozzle exit, and its breakup eventually produces relatively large drops. As the liquid temperature approaches boiling, the intact length and the core drop size decrease. Thus operation close to boiling is desirable for effective atomization. However, the nozzle mass flow rate decreases and practical difficulties are found (owing to “vapor-lock”) as the liquid is heated near boiling. 相似文献