不同滤料固定颗粒床过滤性能对比

在固定床冷态实验装置上研究了平均粒径和稳态过滤压降相近、颗粒形状和表面状况不同的两种滤料(陶瓷球和石英砂)的过滤性能. 结果表明,两种滤料过滤性能变化规律基本一致. 粉尘沉积量(?m)增加,过滤效率先增大后减小,过滤压降偏离稳态过滤压降程度(G)增大. ?m相同时,过滤效率和G均随过滤气速增大而减小,但过滤后期高气速下G与低气速下接近. 增大入口粉尘浓度,总体过滤效率无明显改变,粒径大于0.7 ?m的粉尘过滤效率提高,G更显著. 两种滤料难过滤粉尘粒径均为0.35~0.6 μm. 因颗粒形状和表面状况不同,两种滤料过滤性能存在差异,其它条件相同时,石英砂总体和分级过滤效率均高于陶瓷球,G也较大;增大入口粉尘浓度,石英砂过滤效率随粉尘沉积量变化程度相对较小.     

固定床颗粒层过滤性能分析及预测

使用两种滤料颗粒在一套冷态试验装置上考察了过滤气速和颗粒层厚度对颗粒层过滤性能的影响。结合颗粒层过滤宏观模型,分析了不同操作条件下粉尘比沉积率?对颗粒层粉尘捕集能力偏离初始值程度F和过滤压降偏离初始值程度G的影响,然后预测了过滤效率和压降。结果表明,试验范围内,随着?的增大,F呈现先增加后降低的变化趋势,而G逐渐增加。结合过滤气速u=0.2~0.6 m·s~(-1)、颗粒层厚度L=0.11~0.2 m条件下的试验数据拟合得到了F-σ和G-σ函数关系,过滤效率和压降的计算值与试验吻合较好,优于文献中相关公式,可为颗粒床过滤性能的预测提供参考。     

固定床颗粒层过滤效率的正交试验及回归分析

用固定床颗粒层过滤实验装置,以石英砂为过滤颗粒在常温下进行过滤效率实验。采用四水平正交表安排试验,利用量纲分析和SPSS软件进行多元非线性回归处理试验数据,得到了过滤效率与表观过滤速度、过滤层厚度、过滤颗粒平均粒径、粉尘浓度和过滤时间5个因素的回归方程,从而对过滤效率变化规律进行分析。通过实验表明过滤性能对粉尘粒径具有明显选择性。     

气体的温度和压力及颗粒形状对固定床压降的影响

本文在Ａ－Ｓ方程的基础上推导出气体流经固定床时的压降表达式。     

高温陶瓷过滤管性能退化建模及实时寿命预测

高温陶瓷过滤管由内部孔径较大的支撑体和外部孔径较小的过滤膜双层结构构成,在实际应用中,存在大量粒径较小的粉尘颗粒,会穿过过滤膜沉积到支撑体内部,脉冲反吹无法有效清除. 因支撑体内颗粒沉积及管壁外残余粉尘层不断压缩,使陶瓷过滤管渗透率不断下降,残余压降逐渐增加。本工作基于高温陶瓷过滤管壁内颗粒沉积特性及残余粉尘层压缩不可直接观测的特点,结合贝叶斯估计理论,利用过滤管运行期间采集的残余压降数据,提出一种基于状态空间模型的过滤管性能退化建模方法。该方法能融入最新采集到的残余压降数据,实时对模型参数进行更新,可对陶瓷过滤管的剩余寿命进行实时预测,同时对陶瓷过滤管剩余寿命的失效概率密度分布及陶瓷过滤管的退化状态变化率进行预测。对某高温试验装置及壳牌煤气化装置中的陶瓷过滤管残余压降分析表明,预测剩余寿命准确率随残余压降数据增加而逐渐增加,后期预测准确率高于95%,且陶瓷过滤管退化状态变化率逐渐变小,与陶瓷过滤管残余压降前期增加快后期增加慢的现象一致。     

折叠滤芯气液过滤性能测试及优化

采用聚结型滤芯气液过滤性能实验装置,研究了油雾加载率和表观过滤速度对折叠滤芯过滤性能的影响及涂覆粘合剂对折叠滤芯过滤性能的优化作用。结果表明,涂覆粘合剂后,滤材抗张力强度明显增大,滤材孔径减小。随油雾加载率增大,滤芯过滤层液体运移通道数增加,通道压降升高。初始压降随表观过滤速度增加而升高。粘合剂主要凝固在渗透性低的区域,压降变化较小。表观过滤速度增加抑制了二次夹带,折叠滤芯过滤效率升高,而由于粘合剂脱落,涂覆粘合剂的滤芯过滤效率下降。表观过滤速度为0.10 m/s时,随油雾加载率增大,聚结在滤材表面的粘合剂抑制夹带,滤芯过滤效率升高。     

逆流式移动床过滤器过滤性能的实验研究

通过大型冷模实验考察了气固逆流式移动床过滤器床层表观气速、再生气速对装备操作的影响。在无尘负荷条件下,装备压降随床层表观气速增大呈抛物线式上升的关系;能够用修正的Ergun公式进行预测。通过加尘实验发现,除尘效率与气体停留时间变化趋势相同,且与再生气速呈正相关。床层压降则表现出与床层气速呈正相关、与再生气速呈负相关的变化趋势。实验结果表明,该装备对于粉尘的捕集效率较高,在入口浓度为8.175 g/m³、表观气速在0.122～0.305 m/s范围内,除尘效率始终大于98.0%,且对13μm以下的细微粉尘有较高的粒级效率,接近99.99%。     

聚结层排布对高压天然气净化用滤芯过滤性能影响的实验研究

本工作利用聚结滤芯过滤性能实验装置,通过改变滤芯内部的滤材排布,研究了聚结层为单一滤材以及由不同滤材排布组合的滤芯过滤性能,分析了聚结层排布方式对过滤效率、压降、饱和度及液体分布的影响。结果表明,由单一滤材组成的滤芯过滤效率随滤材孔径减小而增大,但孔径最小时由于压降较高,导致滤芯综合过滤性能反而最差。疏油在前、亲油在后的聚结层排布方式可提高滤芯过滤效率、减少液滴二次夹带,且以两层相同滤材交错排列的滤芯过滤效率比单层滤材交错排列明显更高,压降也相对较低,使得综合过滤性能显著提升。继续增加进气侧的疏油滤材层数可延缓压降增长、提高运行寿命,滤芯稳态品质因子达到最大值(0.30 kPa-1)。聚结层排布方式对滤芯过滤性能的影响主要通过改变液体分布形式而实现,且末层滤材的通道结构变化是导致不同聚结层排布方式的滤芯过滤性能出现差异的主要原因。     

输气站场过滤分离器压降与除尘效率变化特性

为通过压降来评价不同工况下过滤分离器的除尘效率和工作状况,指导现场过滤分离器滤芯的操作和更换,本文以输气站场典型卧式过滤分离器为研究对象,采用粉尘在线检测和计算流体力学（CFD）数值模拟的方法,分析不同运行时间、运行压力下过滤分离器压降和除尘效率的静态与动态特性,并通过现场实际验证。结果表明：在相同标况流量下,操作压力越低,过滤分离器初始压降越高;随着过滤分离器的运行时间增长,其压降检测值将偏离拟合的最优二次曲线,其除尘效率也将呈下降趋势,特别是在运行压力较低时下降更快,其根源在于低压下气流速度快,可携带更多已聚结的颗粒流出,致使下游粉尘浓度上升;CFD方法预测与在线检测的除尘效率误差均低于20%,现场实际除尘量证实两种方法均有较高的准确性与可靠性,且适合过滤分离器压降与除尘效率变化的预测。     

固定床内压降的CFD分析

采用CFD法分析填充单一粒径和不同粒径颗粒固定床内的压降。分别采用PFC3D和Fluent软件建立固定床模型和模拟计算压力场,床层内颗粒流动雷诺数Re_p介于1~2 200之间。将床层空隙率、压降等模拟结果分别与已发表文献中的半经验公式的计算结果进行了比较,发现当Re_p小于120左右时压降的模拟结果与半经验公式计算结果基本吻合;而当Re_p较高时,二者之间的偏差较大;大颗粒使床层内空隙率分布的峰位置向固定床中心移动,第1个峰的位置与固定床壁面之间的距离和颗粒的质量平均直径（d₄₃）值基本相同;采用d₄₃代替半经验公式中的粒径参数,得到的压降计算结果与模拟结果更加吻合。     

炭粒床高效工业除尘装置的设计与开发

The new dust removal technical route using the carbon-granular bed filter,packed of carbon particles with appropriate grade derive from an online-process vibration sieve,to replace the traditional baggy filter had been developed successfully for capturing the micro-carbon dusts produced from pulverization of petroleum coke,and the green close loop of carbon materials is thus completed in the combined pulverizing and classifying system and pulverized carbon dust removal process.The high dust removal efficiency greater than 99%,low outlet dust concentration less than 100 mg.m-3,low pressure drop through dust filtration chamber less than 980 Pa,simple and easy design,and flexible and stable operation were achieved also with the carbon-granular bed filter in both bench and industrial scale operations.     

超重力旋转床微米级粉尘脱除实验研究

以超重力旋转床作为除尘设备,用超细滑石粉模拟工业微米级粉尘,考察旋转床除尘的分离效率和设备压降.在气量500～700 m~3/h、液量0.6～1.0 m~3/h、转速560～1 400 r/min、平面丝网层数为3的条件下,除尘总效率均大于97%,设备总体压降不超过490 Pa.超重力旋转床相对于其他除尘设备,显示了高效除尘和低压降性能.     

Role of bed height and amount of dust on the efficiency of sound‐assisted fluidized bed filter/afterburner

A 40‐mm sound‐assisted fluidized bed filter/afterburner for hot gas clean‐up has been characterized in terms of bed saturation time, total amount of collected particles, fraction of fine particles permanently adhered on the coarse bed particles, and efficiency of using a regeneration strategy based on mechanical (attrition) and/or chemical (combustion) action. Experiments have been carried out at ambient temperature as well as at 850°C, with and without application of sound and varying bed height and amount of dust in the gas flow. The controversial effect of the application of sound: not only enhancement of particles interactions but also increase of fines permanently adhering on bed coarse particles is presented and discussed. A simplified model has been developed to obtain rough predictions of bed height which maximize fine particles capture, bed saturation time, total amount of particles collected in the bed, fraction of fine particles loading present as adhered particles on bed particles. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Hybrid autowaves in filtration combustion of gases in a catalytic fixed bed

A mathematical model of autowave processes in a heterogeneous medium with chemical reactions in the gas phase and on the catalyst is constructed. The coefficients of heat and mass transfer between the phases and the thermal conductivity of the solid phase are determined from the current values of system parameters. The model describes three types of autowaves: waves due to filtration combustion of gases in the low-velocity regime, waves due to a catalytic reaction, and hybrid waves. The behavior of phase trajectories of the dynamic system is studied by methods of qualitative and numerical analysis, and an effective technique is developed for searching for a physically grounded autowave solution of the problem. The laws of propagation of autowaves due to filtration combustion of gases and hybrid autowaves are numerically examined, and the effect of system parameters on the basic technological characteristics of autowave processes is studied. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 3–13, March–April, 2008.     

Validation of pressure drop prediction and bed generation of fixed-beds with complex particle shapes using discrete element method and computational fluid dynamics

Catalytic fixed-bed reactors with a low tube-to-particle diameter ratio are widely used in industrial applications. The heterogeneous packing morphology in this reactor type causes local flow phenomena that significantly affect the reactor performance. Particle-resolved computational fluid dynamics has become a predictive numerical method to analyze the flow, temperature, and species field, as well as local reaction rates spatially and may, therefore, be used as a design tool to develop new improved catalyst shapes. Most validation studies which have been presented in the past were limited to simple particle shapes. More complex catalyst shapes are supposed to increase the reactor performance. A workflow for the simulation of fixed-bed reactors filled with various industrially relevant complex particle shapes is presented and validated against experimental data in terms of bed voidage and pressure drop. Industrially relevant loading strategies are numerically replicated and their impact on particle orientation and bed voidage is investigated.     

水膜除尘器脱硫改造的应用研究

针对水膜除尘器的功能和结构特点,综合运用喷淋洗涤、文丘里高效混合、拦截碰撞等洗涤混合原理,应用一种高效低阻力气体洗涤吸收装置对水膜除尘器进行脱硫改造。工程实践表明,应用该装置对水膜除尘器进行脱硫改造,可以做到除尘脱硫效率高,系统阻力低,投资运行费用低,除尘效率达到98%,脱硫效率大于80%。     

合成氨生产中固定层反应器阻力降分析及降阻措施

阻力降是固定层反应器的重要参数,低阻力降的反应器是工程设计的努力方向,对节能降耗具有重要的意义.通过分析阻力降影响因素,结合变换反应器、甲醇合成反应器、氨合成反应器设计,提出可行的降低床层阻力降的措施,并在工业生产中得到很好的应用.     

混合填料固定床Anammox工艺启动及运行性能研究

采用蜂窝状聚乙烯填料和环型无纺布填料组合成的混合填料填充固定床反应器,考察了其Anammox工艺启动和运行性能。启动阶段进水NH_4~+-N和NO_2~--N分别为70 mg/L,HRT为48 h,温度为35℃,经过53 d培养,反应器成功启动。启动阶段(1~53 d)NH_4~+-N、NO_2~--N和总氮最大去除率分别为90.24%、100%和88.8%。负荷提升阶段(55~87 d)最大总氮负荷率和总氮去除速率分别为0.31 kgN/(m~3·d)和0.25 kgN/(m~3·d),此时,其相应的NH_4~+-N和NO_2~--N去除率分别为89.66%和99.84%。