赤泥沉降分离数据模型建立的新方法——多元正交回归法

本文对赤泥沉降分离的部分影响因素——赤泥浆液固含、沉降温度、絮凝剂浓度设计了正交试验.对赤泥的沉降分离过程建立了数据模型。建立了赤泥沉降的的数据模型H=aLn(t) b,并推导出赤泥沉降分离的速率模型v=(dH)/(dt)=a/t.并通过正交回归法得到了系数a的多元正交回归多项式模型.此模型和试验结果的拟合程度很高,误差不超过5%.     

絮凝剂结构对赤泥沉降速率的影响

考察了絮凝剂不同官能团对赤泥沉降速率的影响差异,采用国外公司最近研发的具有羧基、酰胺基和氧肟酸官能团的3种絮凝剂,并在最佳添加量下,进行了拜尔法氧化铝赤泥絮凝沉降速率的测定,分析了3种官能团不同组合而成的絮凝剂和赤泥的相互作用。从沉降速率、溢流液澄清度和底泥液固比三方面得出含有3种有效官能团的絮凝剂C的絮凝效果最好,比较3种絮凝剂前5min沉降速率,得出C是相对高效的絮凝剂,同时分析了絮凝剂C添加量大是由空间效应导致的,并提出了今后的研究方向。     

煤气化装置黑水沉降槽流场特性的模拟计算

采用CFD软件对煤气化装置竖流式黑水沉降槽进行建模,计算不同工况条件下黑水沉降槽内流场特性,分别讨论了入口流速和排污量对内部流场的影响规律。结果表明：沉降槽内存在射流区、回流区、扩散沉降区,入口流速和出口排污量是影响沉降槽内流场的主要因素,随着入口流速或排污量的增加,射流区和回流区面积增加;不同排污量或入口流速时,不同位置流体的径向流速分布趋势相同。     

斜板和斜翅板沉降槽分离性能的研究

讨论了斜板沉降槽和斜翅板沉降槽中流体流动的特征和液固二相的分离过程，并以两种物料测定了其分离性能。实验结果表明，斜翅板沉降槽的分离性能明显优于斜板沉降槽，而且具有较好的操作弹性。实验还表明，斜翅板沉降槽的翅片数（级数）对其分离效果和操作稳定性有决定性的影响。本研究结果为斜翅板沉降槽设计提供了可靠的依据。     

固液搅拌槽内液相速度的分布

在两个几何相似固 -液搅拌槽内 ,采用双电导探针测定了固体浓度较高的固液体系中液相速度的分布 .固相质量分数从 12 .5 %至 38.2 % (体积分数C_v 从 5 .4 %至 19.8% ) ,搅拌槽直径分别为Ф80 0mm与Ф16 0 0mm ,采用一种高效的长薄叶螺旋桨搅拌器 (CBY)向下泵送操作 .实验研究了固体浓度变化以及搅拌槽放大对液相速度分布的影响 .根据所测速度分布计算了不同直径槽内悬浮液中叶轮的流量准数.     

赤泥流态化洗涤

利用流态化洗涤装置进行了赤泥浆液的流态化洗涤实验研究. 结果表明,当赤泥浆液中Na2O浓度为125~180 g/L、赤泥用水量为4.2~4.9 t/t时,底流附碱浓度可降低至0.25~5 g/L,底流液固质量比为2.2~2.7,溢流Na2O浓度为90~150 g/L. 基于流态化洗涤原理,建立了流态化洗涤的数学模型,可预测洗涤过程浆液中Na2O浓度轴向分布和洗涤效果. 研究结果表明流态化洗涤装置可用于氧化铝生产的赤泥浆液洗涤.     

助滤剂对絮凝物沉降和过滤性能的影响

<正> 一、前言 在液固分离过程中,对于一些直接通过沉降或一般的过滤方法(如真空过滤、加压过滤等)难以分离的悬浮液,化学预处理和物理预处理是改善悬浮液特性使其液固两相得以分离的两种行之有效的方法。目前,这两种预处理方法被广泛地应用于化工、冶金、矿山及环保水处理等行业。本文结合这两种方法的不同特点,将它综合应用于改善某厂粗制液净化过程中产生的悬浮液的沉降和过滤性能,以强化整个液固分离过程,达到液固两相有效分离的目的。     

一种沉降槽高效退槽的工艺设计

赤泥分离及洗涤沉降槽是拜耳法氧化铝生产过程的重要环节之一,目前国内氧化铝生产企业主流采取高效深锥沉降槽技术。因生产过程中铝酸钠水解产生氢氧化铝结疤,给生产系统带来运行隐患,因此需要周期性将沉降槽退出流程清理确保生产运行安全。而沉降槽的周期性退槽清理,就涉及到退槽时间过长、铝酸钠溶液饱和度下降、铝酸钠溶液温度下降等不良因素产生的水解损失。因此,如何在赤泥分离及洗涤生产环节中提高沉降槽退槽效率,减少氧化铝的水解损失从而降低生产成本具有较大的现实意义。     

固-液导流筒搅拌槽内流体流动和颗粒悬浮特性

在直径0.8 m的导流筒搅拌槽内,对单相液体的三维速度分布、固-液两相的固体颗粒浓度分布和离底悬浮特性进行了系统的实验研究. 结果表明,导流筒内外的轴向液相速度远大于径向和切向速度,导流筒外壁附近存在一个与主体轴向流动方向相反的二次流区域;搅拌槽底部结构对固体颗粒的临界离底悬浮转速(NJS)有显著的影响,浅锥底的NJS比平底的低14%以上;NJS随固相浓度的增加而增加,但当浓度超过50%时,NJS略有降低;槽内固相浓度分布的均匀性随固相浓度的增加而得到改善. 本研究结果对导流筒搅拌槽的优化设计具有一定的指导意义.     

拜耳法赤泥强化沉降研究

本文以拜耳法赤泥固化堆存为背景,研究了拜耳法赤泥的物理特性和自然沉降特性,比较了不同促沉剂在不同掺量条件下对赤泥浆体沉降性能的影响;通过正交试验优选出赤泥促沉剂的合理配比:腐植酸钠/萘系减水剂/六偏磷酸钠/十二烷基苯磺酸钠=1/11/2/3,在浓度为40％的赤泥浆体中掺用3.4‰的促沉剂,沉降8h后沉降层浆体浓度可以达到52.6％,24h后沉降层浓度可以达到59.8％;与自然沉降24h相比,沉降层浓度提高了27％;对强化浓缩赤泥进行固化,并与自然沉降赤泥固化体相比,内聚力提高了50％,提高了固化堆存的稳定性和安全性.     

一种新型浓密机进料井结构的研究

通过对传统浓密机进料井结构进行研究,提出了一种结构简单、便于改造的新型浓密机进料井结构。采用计算流体力学的方法对新型进料井结构的内部流场进行了数值模拟,研究了进料井内的迹线分布、出口平面固相体积分数分布和速度分布。结果表明,新型浓密机进料井结构在不同的进料速度下,能够有效耗散进料悬浮液的动能,均匀分布物料。该结构可使物料从进料井的各个方向与径向呈一定角度流出,延长了物料到达溢流堰的时间,溢流液澄清度高,提高了分离效果。新型进料井结构不需要提高任何外动力,节约能耗,在工业上有较大的应用价值。     

Modélisation Mathématique de la Décantation de la Boue Rouge

A good performance of the solid‐liquid unit operation is required for the economical exploitation of the Bayer process. A computational fluid dynamics (CFD) model simulating the operation of the last washing stage mud thickener of a large Canadian alumina plant is presented. The parametric study of the impact of changes in four parameters shows that the diameter of flocculated red mud particles, the feed flow rate and the radius of the feed well are critical parameters for the operation of the thickener.     

操作参数对三相卧螺离心机油水砂分离性能影响模拟及实验分析

首先提出一种新型可调溢流堰板式三相卧螺离心机主体结构，其内部设置了径向排油通道以及位置和大小可调节的溢流堰板。其次，使用计算流体力学软件Fluent、基于欧拉-欧拉多相流模型，对三相卧螺离心机流场及分离性能进行数值模拟，建立三维流域模型、进行网格划分及边界条件设定，对油相及固相浓度分布等进行分析。之后确定实验工艺流程图，搭建油水砂三相分离实验系统平台，建立三相分离实验系统装置，制定实验步骤进行实验研究及测量工作。分别从转鼓转速、处理量等研究了各自对固相回收率、油相回收率、油在滤饼中的损失及油在水中的损失等的影响规律，并从出砂含固、出油含油、出渣含油及出水含油质量浓度等方面对数值模拟结果进行实验验证。     

Experimental Investigation into the Hydrodynamics of Flow of Solids through a Loop Seal Recycle Chamber

The working of loop seal is one of the least understood aspects of a circulating fluidized bed boiler although this component is critical to the operation of such boilers. The present work is an experimental study of the flow of solids; through the recycle chamber of a loop seal in a circulating fluidized bed (CFB). The effect of different parameters on the velocity of solid overflow through the recycle chamber is investigated. The sharp‐crested weir theory of free surface water flow was used to analyze the solid flow through the loop seal. The analysis gives a good indication of the validity of the above theory for solids overflow over a weir. The results show that the solid flow rate increases with increase in bed height above the weir and the particle size had no effect on the value of the weir coefficient.     

Effects of geometric and operating parameters and feed characters on the motion of solid particles in hydrocyclones

The effects of geometric and operating parameters and feed characters on the motion of solid particles in hydrocyclones were experimentally investigated by using a new type of laser surveying instrument named particle dynamics analyzer. The absolute radial velocity of solid particles decreases with increasing the positional radius, and the axial distribution curves of the particle radial velocity are parabolic. The particle radial velocity increases with increasing the inlet pressure or with increasing the diameter of the underflow pipe. When the particle density or the particle size increases, the absolute radial velocity of the solid particles decreases. The particle radial velocity also decreases with increasing the feed particle concentration. The axial distribution curves of the particle axial velocity are also parabolic. The axial velocity in the inner helical flow increases with the increase of the flow rate of overflow; while that in the lower positions in the outer helical flow increases with increasing the flow rate of underflow.     

强化细煤泥沉降工艺的实践

白龙选煤厂在煤泥水处理流程中,针对入选原料煤中细泥含量不断增加、高灰细泥不能有效沉淀等问题,采用无机凝聚剂CaO和有机絮凝剂聚丙烯酰胺配合添加技术,工艺指标得到了显著改善,浓缩机清水层稳定在1.5~2.0m,溢流浓度达到10g/L,解决了生产难题,底流固体物回收率增加,获得了较好的社会和经济效益。     

赤泥水浸脱碱实验及动力学研究

赤泥是一种碱性污染物,强碱性是制约其综合利用的关键因素。进行了拜耳法赤泥水浸脱碱实验及动力学研究,实验结果表明：赤泥在水浸次数为4次、液固体积质量比为9 mL/g、反应温度为90 ℃和反应时间为60 min的条件下,赤泥的脱碱率可达71%。采用未反应收缩核模型对水浸脱碱数据进行线性拟合,动力学分析表明：活化焙烧后赤泥的水浸脱碱过程受扩散步骤控制,线性相关系数大于0.97,表观活化能为11.72 kJ/mol。     

The effect of shear on gravity thickening: Pilot scale modelling

Mathematical models are potentially a valuable tool for the prediction of continuous gravity thickener operation. However, experience shows that existing mathematical models underestimate dewatering in thickeners for flocculated feed materials when predictions are made of either the underflow solids concentration for a given solids feed flux density or the maximum solids feed flux density achievable for a minimum underflow solids concentration set point. One reason postulated for this discrepancy is shear enhancement of sedimentation and bed dewatering as a result of aggregate densification. This process is not taken into account in conventional 1-D thickener models. A pilot scale column, operated at low bed heights without the addition of mechanical shear, produced results that compared well with 1-D model predictions. The effect of mechanical shear and/or greater bed height was to significantly enhance thickener performance relative to model predictions (as measured by underflow density or maximum solids flux density achievable for a nominated underflow density). An experimental method was developed that enabled shear to be incorporated into the suspension dewatering characterisation. The results suggest an order of magnitude increase in solid flux density can be expected under controlled shear conditions with polymer flocculated aggregates. The results also indicate that mechanical shear is not the only factor that can enhance dewatering, since higher beds, and hence longer residence times, also improve the achievable solids flux density. This is despite the fact that the thickener is operating in a regime that is predicted to be limited by the sediment permeability and not its compressibility. This suggests an additional mechanism must be at play in full scale operation and points a direction for further experimentation.