填料塔泛点/压降模型计算比较

以文献报道的实验数据及关联式为基础 ,比较了Billet模型、S -B -F模型及常用泛点 /压降计算模型在国产散堆和规整填料的泛点 /压降上的计算偏差 ,并对国产散堆和规整填料的泛点 /压降计算模型进行了总结     

散装填料层泛点和压降的新关联

在理论分析的基础上 ,导出了散装填料层泛点气体速度和压降的新关联式 ,由实验数据计算了常用填料新关联式的液泛填料因子和压降常数。新泛点关联式对 8种填料泛点气速的计算值与实验数据的总平均计算误差为 3.5 2 % ;新压降关联式对各种填料的压降平均计算误差一般在 10 %以下。关联值与实验数据吻合很好 ,计算准确性优于文献公式 ,且比文献公式计算简便。     

筛板塔漏液点气速的计算模型

本文从力平衡角度出发,并考虑到筛板上气液混合层的截面含气率和液面波动的影响,指导出筛板的漏液点气速的计算模型,可用于工程设计计算。     

填料因子变化时散堆填料泛点气速数值算法

泛点气速是填料塔设计的重要参数,Eckert关联图为目前工程上运用较为广泛的泛点气速求取方法。文中基于散堆填料的Eckert关联图,在考虑泛点填料因子f随液体泛点喷淋密度Lf变化的条件下,提出了泛点气速uf的数值算法;推导出泛点气速uf的表达式为一个高度非线性化方程,并给出了该方程的2种求解方法。同时举例计算了一个散堆填料的泛点气速,并和著名的塔器流体力学计算软件(WPTR)计算结果做了对比。结果表明:文中的计算结果和WPTR的结果完全吻合;所使用的方程求解方法 Aitken-Steffensen具有快速、稳定的收敛性,可用于散堆填料的泛点气速计算。     

填料塔液泛气速,压力降计算方法的讨论

使用部分Ｄｇ５０瓷质填料在水－空气实验系统中测得的填料塔液泛气速和压力降,根据所确定的液泛气速,压力降的计算方法,推算出９３％Ｈ２ＳＯ４－空气９３％Ｈ２ＳＯ４－ＳＯ２烟气,９８％Ｈ２ＳＯ４－ＳＯ３烟气等操作系统中,填料塔采用不同填料的液泛气和压力降。     

QH-2型扁环填料的流体力学和传质性能研究

在内径60 0填料塔中 ,用空气 富氧水系统对3 8和5 0QH 2型扁环填料的流体力学和传质性能进行了研究 ,得出计算其压降、液泛气速和传质单元高度的关联式。并与3 8鲍尔环、5 0鲍尔环和3 8环矩鞍填料进行了比较 ,结果表明 ,QH 2型扁环具有优良的流体力学和传质特性。     

散装填料层泛点和压降的新关联式

导出了散装填料层泛点和压降的新关联式,将该关联式与通用关联图进行了比较,计算结果表明,新关联式对各种填料的压降平均计算误差在10％以下,泛点计算误差在7％以下,计算准确性优于通用关联图;用通用关联图计算压降有时误差较大。     

计算散装填料层泛点的新方法

在半理论分析的基础上,导出了散装填料层泛点气体速度的关联式,由实验数据计算了常用填料本文关联式的液泛填料因子。本文泛点关联式对8种填料泛点气速的计算值与实验数据的总平均计算误差为3.52%,新关联方法与实验数据吻合很好,计算准确性优于文献公式,且比文献公式计算简便。     

用于高液气比吸收过程的填料优选和数学模型的研究

在(φ)600填料塔中,用空气-富氧水系统在很宽的液体喷淋密度范围内(20～220 m3/(m2·h))对(φ)50QH-2扁环、(φ)63 QH-2扁环、Mellapak 125X、与(φ)38 鲍尔环的流体力学和传质性能进行了研究,结果表明,与鲍尔环相比,QH-2扁环的阻力小,通量大,传质效率高,综合性能优异.而Mellapak 125X通量虽然很高,但传质效率明显低于QH-2扁环和鲍尔环.给出了计算QH-2扁环压降、液泛气速和传质单元高度的关联式.     

QH-1型扁环填料萃取塔的设计计算——液泛速度的计算

在系统实验研究的基础上，选择基于特性速度的方法，得出用于中低界面张力体系的ＱＨ－１扁环填料萃取塔的液泛速度计算公式，可用于工业装置的设计计算。     

工业级水平管粉煤气力输送的最小压降速度和稳定性

采用压缩空气作为输送介质,在工业级水平管(内径50 mm)上开展了粉煤密相气力输送实验研究。在实验获得最小压降速度基础上,通过电容层析成像系统观察到,随着表观气速降低而存在分层流、沙丘流、移动床流以及栓塞流4种流型。不同流型压力信号的概率密度分布和功率谱密度分析表明,压力信号的波动特征与流型紧密联系;由于流动形态的变化,存在由稳定输送过渡到不稳定输送的临界气速,且该速度小于最小压降速度。     

超级扁环填料及其在氮肥厂气体净化过程中的应用

国内外最新的研究工作表明,在液液萃取、液气比很大的吸收和高压精馏的情况下,应用散装填料的操作性能优于规整填料和塔盘。其中扁环填料具有独特的结构和优异性能。本文介绍了从阶梯短环到超级扁环的发展过程、技术特点和在合成氨气体净化中的应用。     

Prediction of minimum velocity and minimum bed pressure drop for gas-solid fluidization in conical conduits

Experimental investigations have been carried out for spherical and non-spherical particles using beds comprised of single-sized particles and mixtures in the size and particle density ranges of 439 to 1524 μm and 1303 to 4948 kg/m³, respectively. Five conical fluidizers with varying apex angles of 8.86, 14.77, 19.60, 32.0 and 43.2 degrees were used. Experimental values of minimum velocity and bed pressure drop with air as the fluidizing medium have been compared with their respective values obtained from different models available in the literature. Deviations for each chosen model have been presented.     

气-固微型流化床压降特性及最小流化速度的实验研究

在内径3～20 mm的4个气-固微型流化床中,分别考察了A类和B类两种类型颗粒的流化特性,同时研究了床几何结构、操作条件、物相性质等各因素对其最小流化速度的影响.结果 表明,气-固微型流化床中的床层压降特性与颗粒类型密切相关,不同的流动状态下两种类型颗粒的流动特性存在显著地差异.在固定床阶段,与B类颗粒相比,A类颗粒与...     

上升管内环状流含液体积分数与压降预测模型

对垂直上升管中气液二相环状流的含液体积分数及压降预测进行了研究,在充分考虑了环状流的流型特征以及合理假设的前提下,以二相流动力学理论和Wallis有关经验式为基础,推导出了环状流的数学模型。通过求解力学方程,获得了含液体积分数及压降预测的新模型,将新模型及已有模型与实验数据进行对比,结果表明,新模型不仅与实验结果符合良好,还具有计算速度快的特点,从而为垂直上升管内气液二相环状流含液体积分数与压降的预测提供了一种新的有效方法。     

Flow regimes and pressure drop of a composite tridimensional rotational flow sieve tray under concurrent gas-liquid flow

A composite tridimensional rotational flow sieve tray (CTRST) is proposed. The flow patterns of CTRST were visually categorized, combined with the standard deviation of the pressure difference. In the TRST area of the internal packing-type tray, the membrane-drip column and foam-embolic flow is present, while bubbly and milk froth-ribbon flow is present in the packing area of the external packing-type tray. The effect of the tray structure parameters on the pressure drop under co-current flow was investigated. The dry and wet pressure drop is within 160 and 900 Pa, respectively. Under the same structural parameters, the pressure drop of the internal packing-type tray was higher than that of the external packing-type tray. The flow characteristics of the standard tray under the countercurrent flow were compared. The CTRST was found to be more suitable for co-current flow. A prediction model pressure drop under co-current was established with an error of 15.5%.     

R1234ze(E)在泡沫金属管内的流动沸腾换热和压降特性

泡沫金属具有超大比表面积和高热导率,将其填充于换热管内可用于制冷空调系统的强化传热。研究了R1234ze(E) 在泡沫金属管内的流动沸腾换热和压降特性。实验工况为：干度0.1~0.9,质流密度90~180 kg·m^-2?s^-1,热通量12.4~18.6 kW·m^-2。测试样件为泡沫铜填充管,孔密度为10~40 PPI、孔隙率为90%~95%。实验结果表明,R1234ze(E) 比R410A的传热系数低2%~10%,两相压降低30%~42%;当干度大于0.8时,低质流密度下泡沫金属管内传热系数随干度的增加增幅更大;泡沫金属在强化流动沸腾换热的同时,造成压降显著增加,换热影响因子的范围为1.23~2.90,压降影响因子的范围为6~45。开发了适用于R1234ze(E) 的泡沫金属管内流动沸腾换热和压降关联式,传热系数和两相压降的预测值与95%的实验值误差分别在±15%和±25%以内。     

Effects of cross-flow velocity, capillary pressure and oil viscosity on oil-in-water drop formation from a capillary

The formation of oil drops from a single capillary with a diameter of 200 μm into a cross-flowing continuous water phase has been studied experimentally with the particle image velocimetry (PIV) technique and numerically with the computational fluid dynamics (CFD) software Fluent. The drop formation time and the volume of the detached drop were used as validation parameters and the results from the two methods corresponded well, with a difference of less than 5% for the drop formation time and 10% for the drop volume. The cross-flow velocity has a major impact on drop size, which decreases as the cross-flow increases. An increase in cross-flow, oil viscosity and capillary pressure displace the position of necking and drop detachment away from the capillary opening, which will have a decreasing effect on the final size of the drop.     

Numerical and experimental study on the effect of solid particle sphericity on cyclone pressure drop

The continuous flow inside cyclone separator is usually simulated by solving the Reynolds averaged Navier–Stokes equations in Eulerian reference frame whereas the dispersed phase is modeled using Lagrangian approach. Although these methods have had a remarkable success, more advanced ideas are needed to model particulate phase in cyclones, especially the non-spherical shaped particles. Numerical simulation is verified with experimental results for the gas-solid flow in a cyclone separator. Reynolds Averaged Navier–Stokes equations (RANS) employing the RNG-based k–ε turbulence model are used to simulate the gas phase. 3-D particle tracking procedure is used for the solid phase. Three different equations for the drag coefficient are utilized in the numerical modeling to acquire more understanding of the behavior of non-spherical particles in cyclones. Computations resulted in the difference of pressure between the inlet and exit of the cyclone, and results are compared with experimental data. Experiments included measuring the separation efficiency of different shapes and sizes of particles. The results indicate that the CFD simulation can effectively reveal the pressure drop behavior as well as separation efficiency of gas-non-spherical particle flow in cyclone.