陶瓷过滤管表面粉尘层清除过程的图像分析

Based on the analysis of high-speed video images, the detachment behavior of dust cake from the ceramic candle filter surface during pulse cleaning process is investigated. The influences of the dust cake loading,the reservoir pressure, and the filtration velocity on the cleaning effectiveness are analyzed. Experimental results show that there exists an optimum dust cake thickness for pulse-cleaning process. For thin dust cake, the patchy cleaning exists and the cleaning efficiency is low; if the dust cake is too thick, the pressure drop across the dust cake becomes higher and a higher reservoir pressure may be needed. At the same time there also exists an optimum reservoir pressure for a given filtration condition.     

Effect of the Solid Loading on a PFBC Cyclone with Pneumatic Extraction of Solids

This paper presents the effects of solid loading on the performance of a cyclone with pneumatic extraction of solids. The cyclone is a non‐conventional design, especially used for hot‐gas cleaning applications such as pressurized fluidized bed combustors (PFBC). A scaled‐down cold‐flow model was employed for the research. Experiments were conducted at 9–14 m/s inlet gas velocities, inlet solid loadings ranging from 30 to 230 g/kg gas, and bottom gas extraction percentages from 0.3 to 1.5%. Experimental results of pressure drop resistance coefficients and collection efficiency were compared with literature predictions. At PFBC operating conditions, cyclone geometry and solid concentration are the main parameters influencing cyclone pressure drop and collection efficiency. The vortex penetration in dipleg causes lower pressure drop values and higher collection efficiencies than predicted. These parameters can be suitably predicted for PFBC cyclones by introducing a modified penetration length in Muschelknautz's model [1]. For the present cyclone design, a new correlation of pressure drop, including the influence of solid loading, is proposed. A new method for detecting cyclone fouling, not previously addressed, is also presented, based on the evolution of the pressure drop resistance coefficient. An enhanced separation efficiency has been found, related to collection efficiency, which is especially important for particle sizes below 10 μm revealing agglomeration effects.     

Experimental Study of Particle Collection by Small Cyclones

A new set of experimental data on the particle collection characteristics of small cyclones is reported. The collection efficiency for particles ranging from 2 to 10 μm in diameter was measured systematically for nine cyclones at flow rates ranging from 8.8 to 18.4 L/min. Special emphasis was given to the effects of the exit tube size and of the cyclone body size on the particle collection efficiency. The size ratio of the exit tube to the cyclone body was varied from 0.24 to 0.80. The experimental results show that the stiffness of the particle collection cutoff with size does not change noticeably with a change in the cyclone body size while operation of a cyclone at a low flow rate can cause the particle collection characteristics to become less stiff. It was also found that the exit tube diameter influences the particle collection efficiency substantially, with results showing that as the exit tube size is decreased, the collection efficiency increases. A large cyclone body size increases the efficiency. However, when the cyclone body is increased excessively, the collection efficiency appears to decrease somewhat. The experimental data were compared with existing cyclone theories and Barth's (1956) theory was found to be in good agreement. Finally, the exit tube was found to affect substantially the pressure drop of cyclones. As the exit tube size increased, the pressure drop decreased. However, when the exit tube size was further increased until it approached the body size, the pressure drop increased again.     

差异旋风分离器并联性能测量及流场分析

通过改变旋向和芯管直径,设计了3种差异旋风分离器,并按中心对称方式组成了3种并联方案：相同分离器、旋向差异分离器和芯管差异分离器并联。在冷态实验装置上,测量了单分离器和并联分离器的性能,并利用FLUENT软件分析了并联分离器的流场。结果表明,并联分离器的效率均高于单分离器,且效率-气速曲线未出现“驼峰”;与相同分离器并联相比,旋向交替变化时并联总压降较小,分离效率也更低,但各分离器流量分配均匀,未发现“窜流”现象;当芯管有差异时,并联总压降增大,各分离器进口流量分配不均匀,且进、出口流量平均相差6.0%,公共灰斗中存在“窜流”,旋流稳定性变差,效率降低。为了保证并联分离器的性能,应采用相同分离器对称并联的方式。     

Optimization of parallel cyclones

A new procedure is presented to optimize the number and size of parallel cyclones. For a given efficiency, constraints due to inlet velocity and pressure drop limitations are taken into account.An analytical solution is obtained, and an iterative method of calculation is proposed to check constraints and to search for the existence of a ‘better’ optimum at lower values of d₁. The method can also be applied to optimize the size of a single cyclone.     

除油型旋流器压降比特性试验研究

在室内试验装置上对单锥除油型水力旋流器的压降比特性进行了试验研究。研究结果表明 ,除油型旋流器压降比的主要影响因素有分流比、入口流量和溢流背压等操作参数 ;溢流背压对压降比的影响存在一“门槛值”。根据试验结果 ,建立了除油型水力旋流器压降比的半经验计算模型     

Experimental investigation of the performance of a large-scale scrubber operating at elevated pressure on live natural gas

Experimental results for the performance of a near-full-scale natural gas scrubber operating on a live natural gas system at high pressure are given in this article. The scrubber configuration has three types of internals in series: an inlet vane, a mist-mat and an axial cyclone bank. The variations with pressure of the fluid properties of the natural gas system are calculated and given, and the performances of the over-all scrubber and of the individual internals at a range of gas and liquid flows and at three different pressures up to 113 barg are shown. The results show that beyond a Souders-Brown K-value of 0.15 m/s, the primary separation efficiency breaks down and that beyond this value of K, the scrubber relies on the cyclones for satisfactory separation. However, at a K-value of 0.26 m/s, the cyclone separation efficiency was poor at high pressure and decreased with increasing pressure. The liquid distribution to the cyclones was highly non-uniform, the outer cyclones receiving much more liquid than the inner ones.     

Zur Frage der optimalen Reinigungsbedingungen für Schlauchfilter mit DruckstossabreinigungInvestigations on optimal cleaning conditions for bag filters with pulse jet cleaning

Pressure drop, residual dust quantity, cleaning intensity as well as the time-dependent outlet dust concentration have been measured in a pulse-jetIn this paper, examples of the measuring results are given and correlations between the cleaning intensity and the outlet dust concentration are discusIt is shown that an optimum cleaning pressure exists at which the dust cake was completely removed. At this cleaning pressure the outlet dust concentra     

Modeling and multi-objective optimization of square cyclones using CFD and neural networks

Increasing of collection efficiency (η) and decreasing of the pressure drop (Δp), simultaneously, are important purpose in the design of cyclone separators. In the present study, multi-objective optimization of square cyclones is performed at three steps. At the first step, collection efficiency (η) and the pressure drop (Δp) in a set of square cyclones are numerically investigated using CFD techniques. Two meta-models based on the evolved group method of data handling (GMDH) type neural networks are obtained, at the second step, for modeling of η and Δp with respect to geometrical design variables. Finally, using obtained polynomial neural networks, multi-objective genetic algorithms are used for Pareto based optimization of square cyclones considering two conflicting objectives, η and Δp. It is shown that some interesting and important relationships as useful optimal design principles involved in the performance of square cyclones can be discovered by Pareto based multi-objective optimization of the obtained polynomial meta-models. Such important optimal principles would not have been obtained without the use of both GMDH-type neural network modeling and the Pareto optimization approach.     

大差异颗粒分级再生设备的性能研究

通过改变表观气速U、颗粒循环速率W、粉尘/捕集颗粒比R等操作参数,考察了大差异颗粒空气分级设备在设置内构件前后的压降和分级效率的变化。结果表明,自由床时,压降随表观气速的增大而增大,分离效率在U=0.27 m/s时达到最大值87%。捕集颗粒循环量对压降的影响较小,分级效率随W的增大而持续下降。粉尘/捕集颗粒比较低时,压降无变化,但增大至超过约翰逊网的阻塞限度后,操作压降呈指数型增长,分级效率迅速下降。设置内构件后,由于其起到了整流和分布作用,设备压降和分级效率的变化不如自由床时敏感,拓宽了可操作的粉尘/捕集颗粒比范围,但缩小了可操作的表观气速范围。将设备实际压降划分为约翰逊网压降、颗粒摩擦压降、气体出口压降三个部分,基于实验结果,给出了计算压降的模型。     

旋风筒阻降浅论

介绍了旋风筒阻降(压降)的定义及其测量方法、旋风筒阻降的计算公式,分析了操作参数和结构尺寸对旋风筒阻降的影响、旋风筒阻降的种类及各种减阻措施。     

Effects of separation space diameter on the performance of a novel reverse flow cyclone

ABSTRACT

A numerical study was carried out to investigate the effect of separation space diameter on the performance of a novel reverse flow tangential inlet cyclone design by using the Eulerian-Lagrangian approach. The design of this cyclone is based on the idea of increasing vortex length and decreasing pressure drop compared with traditional cyclones. This novel cyclone differs from the traditional cyclones with separation space and vortex limiter instead of the conical part. A qualitative numerical study was performed to analyze the effect of separation space diameter on the cyclone performance at different flow rates by evaluating velocity profile, pressure drop, fractional and overall efficiencies. The results show that the collection efficiency of smaller particles increases while pressure drop decreases significantly with the increase in separation space diameter for D₁/D < 0.5.     

Experimental study of filter clogging with monodisperse PSL particles

A fibrous filter is a common cleaning device often used to remove particle from industrial gas streams. The main question that often arises concerns the evolution of the pressure drop and the filtration efficiency during the filter clogging. The increase of pressure drop and filter efficiency was measured and was linked to both the clogging degree inside the filter bed and the deposit structure observed thanks to scanning electron micrograph. We have also studied the influence of various parameters such as air velocity, particle size, aerosol concentration and filter main characteristics. An empirical equation for predicting the pressure drop across the filter as a function of inverse particle diameter and Cunningham correction factor was suggested without considering the particle density in the cellulose paper filter. The values of porosity, obtained from the pressure drop responses of loading in the paper filter using Rudnick and First equation, were compared with other researchers.     

新型湍冲洗涤塔的设计与应用

介绍了新型湍冲洗涤塔结构和设计特点。该塔集动力波洗涤器、洗涤塔、循环槽和沉降槽4台设备功能于一体,具有占地面积小、操作简单、运行可靠、净化效率高等优点。在金川集团6套硫酸装置中的应用表明,采用该新型湍冲洗涤塔后净化工序各项指标良好,出塔气温在65℃以下,塔压力降在1.2 kPa左右,进干燥塔气体的尘含量小于2 mg/m~3。     

A CFD study of the effect of cone dimensions on sampling aerocyclones performance and hydrodynamics

This work presents a Computational Fluid Dynamics calculation to evaluate the effects of cone dimensions on the performance, hydrodynamics and centrifugal forces of sampling aerocyclones (gas cyclones). The problem of modeling highly swirling flow is overcome by means of an algebraic turbulence model. The axial and tangential velocities in a cyclone are successfully simulated. The refined mesh on the cyclone cone was also applied to ensure a better prediction on the effect of cone tip diameter to its performance, centrifugal forces and hydrodynamics. The pressure drop, grade efficiency and cut-off size of a cyclone of different cone dimensions was predicted very well with average deviation of about 2.9%, 5% and 2.1% respectively from experimental data presented in the literature. The findings suggest that the higher peak of tangential and axial velocity in a cyclone of a small cone lead to a higher collection efficiency and pressure drop. This helps to assess the benefit of enlarging or reducing the cone of a given cyclone. Results obtained from the computer modeling have demonstrated that CFD is suitable for modeling an effect of cyclone dimension on its performance.     

旋风分离器进口涡旋感生速度场的减阻增效作用

旋风分离器进口段管路的结构关系着进口气速的分配,直接影响到下游分离空间三维速度场的形式,合理设计进口管的样式是挖掘分离器分离潜力的可能入手之处。采用实验及数值模拟手段,对环管和直管2种进口管路下轴对称双进口分离器的性能与流场作了对比研究。结果表明,环管进口的分离器分离总效率比两侧进口的平均高1.5个百分点,而压降损失降低25%以上。前者阻力小的原因在于进口环管内气流为局部的涡旋,与分离器内旋涡流动的形式接近,两股气流交汇时碰撞程度轻,附加的额外能耗较小;而总效率提高的原因为,环管进口的分离器切向速度比两侧进口的分离器约高0.15倍进口气速,能增强颗粒受到的离心作用、减小切割粒径,从而提升分离器总效率。根据涡旋理论,局部区域的涡旋会对整个流动空间产生感生的速度场,由于环管进口的分离器进口管内局部涡旋的存在,整个分离空间的切向速度场被增强。这种由涡旋感生速度场提升分离器切向速度的方式,加深了分离器运行过程中压头向速度转换的程度,不会消耗额外的能量。因此,采用旋涡流的进气方式,并合理提高进口涡旋的强度,是分离器分离性能进一步提升的新途径。     

A Mathematical Model to Compare the Efficiency of Cyclones

Tangential cyclones modified to form spiral cyclones are very efficient in separating solid particles from dust laden gases. They offer a lower gas pressure drop and higher particle separation efficiency when compared to basic tangential cyclones. Their high performance is believed to be related to their special structure. A mathematical model is introduced to explain why a spiral cyclone is more efficient than a tangential one. An experimental apparatus is designed to compare both the performances of spiral and tangential cyclones and to check the effectiveness of the model equations. The experimental data were found to be consistent with the model predictions.     

碳化硅陶瓷膜管高温除尘实验研究

采用自制碳化硅陶瓷膜管对某电厂烟气进行了高温过滤性能和再生效果的实验研究。主要考察了三种陶瓷膜管的处理气量对过滤效率、阻力损失的影响以及反吹再生效果。结果表明,随着含尘烟气量的增加,过滤效率逐渐降低,同时压降损失逐渐增大;复合膜的过滤性能优于单一膜或支撑体,反吹再生效果最佳。     

Equipment for extracting magnesite dust from drying drums

Conclusions The dry method of purifying flue gases behind drying drums for drying magnesite, using group equipment of cyclones TsN-15 designed by NIIOGAZ, is effective, simple, and convenient.Translated from Ogneupory, No.1, pp.63–64, January, 1967.     

清灰效率对炷状陶瓷过滤器的影响

研究了脉冲清灰效率对过滤过程的影响。假定粉尘结构在过滤和清灰中不变的条件下 ,对清灰效率的影响进行了分析。发现在一定的启动压降下 ,存在着一个最佳的清灰效率 ,即在 90 %～ 95 %之间。由于在运行的前几个循环中 ,粉尘压降、残留粉尘压降以及粉尘厚度、残留粉尘厚度存在较大的变化 ,因而在开始的几个循环中 ,不宜采用相同的清灰时间间隔