陶小凡 -
离心机主要用于将悬浮液中的固体颗粒与液体分开；或将乳浊液中两种密度不同，又互不相溶的液体分开(例如从牛奶中分离出奶油)；它也可用于排除湿固体中的液体，例如用洗衣机甩干湿衣服；特殊的超速管式分离机还可分离不同密度的气体混合物；利用不同密度或粒度的固体颗粒在液体中沉降速度不同的特点，有的沉降离心机还可对固体颗粒按密度或粒度进行分级。
离心机大量应用于化工、石油、食品、制药、选矿、煤炭、水处理和船舶等部门。
工业用离心机按结构和分离要求，可分为过滤离心机、沉降离心机和分离机三类。
离心机有一个绕本身轴线高速旋转的圆筒，称为转鼓，通常由电动机驱动。悬浮液(或乳浊液)加入转鼓后，被迅速带动与转鼓同速旋转，在离心力作用下各组分分离，并分别排出。通常，转鼓转速越高，分离效果也越好。
离心分离机的作用原理有离心过滤和离心沉降两种。离心过滤是使悬浮液在离心力场下产生的离心压力，作用在过滤介质上，使液体通过过滤介质成为滤液，而固体颗粒被截留在过滤介质表面，从而实现液-固分离；离心沉降是利用悬浮液(或乳浊液)密度不同的各组分在离心力场中迅速沉降分层的原理，实现液-固(或液-液)分离。
还有一类实验分析用的分离机，可进行液体澄清和固体颗粒富集，或液-液分离，这类分离机有常压、真空、冷冻条件下操作的不同结构型式。
衡量离心分离机分离性能的重要指标是分离因数。它表示被分离物料在转鼓内所受的离心力与其重力的比值，分离因数越大，通常分离也越迅速，分离效果越好。工业用离心分离机的分离因数一般为100～20000，超速管式分离机的分离因数可高达62000，分析用超速分离机的分离因数最高达610000。决定离心分离机处理能力的另一因素是转鼓的工作面积，工作面积大处理能力也大。
过滤离心机和沉降离心机，主要依靠加大转鼓直径来扩大转鼓圆周上的工作面；分离机除转鼓圆周壁外，还有附加工作面，如碟式分离机的碟片和室式分离机的内筒，显著增大了沉降工作面。
此外，悬浮液中固体颗粒越细则分离越困难，滤液或分离液中带走的细颗粒会增加，在这种情况下，离心分离机需要有较高的分离因数才能有效地分离；悬浮液中液体粘度大时，分离速度减慢；悬浮液或乳浊液各组分的密度差大，对离心沉降有利，而悬浮液离心过滤则不要求各组分有密度差。
选择离心分离机须根据悬浮液(或乳浊液)中固体颗粒的大小和浓度、固体与液体(或两种液体)的密度差、液体粘度、滤渣(或沉渣)的特性，以及分离的要求等进行综合分析，满足对滤渣(沉渣)含湿量和滤液(分离液)澄清度的要求，初步选择采用哪一类离心分离机。然后按处理量和对操作的自动化要求，确定离心机的类型和规格，最后经实际试验验证。
通常，对于含有粒度大于0.01毫米颗粒的悬浮液，可选用过滤离心机；对于悬浮液中颗粒细小或可压缩变形的，则宜选用沉降离心机；对于悬浮液含固体量低、颗粒微小和对液体澄清度要求高时，应选用分离机。
离心分离机未来的发展趋势将是强化分离性能、发展大型的离心分离机、改进卸渣机构、增加专用和组合转鼓离心机、加强分离理论研究和研究离心分离过程最佳化控制技术等。
强化分离性能包括提高转鼓转速；在离心分离过程中增加新的推动力；加快推渣速度；增大转鼓长度使离心沉降分离的时间延长等。发展大型的离心分离机，主要是加大转鼓直径和采用双面转鼓提高处理能力使处理单位体积物料的设备投资、能耗和维修费降低。理论研究方面，主要研究转鼓内流体流动状况和滤渣形成机理，研究最小分离度和处理能力的计算方法。
The centrifuge is mainly used for solid particles and will suspension liquid separated, In the emulsion or two different from each other, the liquid phase dissolved apart from milk (such as isolated cream), It can also be used to eliminate the liquid, such as wet solid with wet clothes washing machine, Special speeding tubular centrifuges are separable different density of the gas mixture, Use different density and particle size of solid particles in the liquid settling velocity different characteristics, but also on the settlement of centrifuge solid particles by density or selecting.and.A centrifuge used in chemical, petroleum, food, pharmaceutical, dressing, coal, water treatment and shipping department.According to the structure and industrial used centrifuge separation requirements, can be divided into filtering centrifuges, centrifuge and centrifuges.A centrifuge around the axis high-speed rotating cylinder itself, called the drum, usually by motor drive. Suspension (or emulsion) join drum after being driven and drum with speed rotating centrifugal force, and in the separation, and components. Usually, drum rotational speed, the higher the better the separation effect.The principle of centrifuge is centrifugal filter and centrifugal sedimentation two kinds. Centrifugal filter is made and produced by centrifugal suspending liquid centrifugal filter medium pressure acting on the liquid through a filter medium, and solid particles as filtrate being trapped in the filter medium surface, so as to realize the liquid-solid separation, Centrifugal sedimentation is using the suspension emulsion (or) of different density components in centrifugal field in the principle, realize the settlement of layered liquid-solid (or liquid-liquid).And those with the experimental analysis on liquid separator, clarification and solids concentration, or separation of liquid centrifuge, this kind of atmospheric and vacuum freeze-drying, is under the condition of different types of operation.Measure centrifuge is an important index of separation separation factor. It said were separated at drum materials within the centrifugal force of gravity, and the ratio of the separation factor and the rapid separation also usually, separation, the better the results. Industrial centrifuge, the separation factor generally for 100 ~ 20,000 tubular centrifuges, speeding up the separation factor analysis, with speed centrifuge 62,000 610000 topped the separation factor. The decision centrifuge, another factor is the work of a drum, large area processing capacity.Filtering centrifuges and sedimentation centrifuge, rely mainly on increasing drum drum diameter to expand the circle on the face, Except a drum machine, and additional circle wall face, such as the disk of the disc separator and room type of machine, a significant increase in the mining subsidence.In addition, the suspension of solid particles in the rules, the more difficult the filtrate or separation of the separation of fine particles increases, in this case, centrifuge needs to have higher separation factor can effectively separated, In the suspension liquid viscosity, separation slowed, Suspension emulsion or components of the density difference, centrifugal sedimentation centrifuge, and suspension is not required components have density difference.Choose centrifuge should according to suspension (or emulsion) of solid particles size and concentration, solid and liquid (or two liquids), liquid viscosity, density phosphate-contained residue (or sediment), and the characteristics of separation requirements analysis, etc. To meet cake (sediment) moisture content and filtrate (liquid) clarify degrees of separation, preliminary selection using which kind of centrifuge. Then according to the operation capacity and automation, determine the types and specifications, centrifuge last practical test.Usually, containing more than 0.01mm particles size of suspension, can choose filtering centrifuges, For suspending liquid in tiny particles or compression, appropriate chooses settlement centrifuge, For suspending liquid containing solid particles is low, the tiny and liquid require high degree of clarification, should choose separator.Centrifuge, the development trend of the future will be strengthened, the development of large-scale separation, improving slag discharge centrifuge, special and combination institution, strengthening separation drum centrifuge and theoretical research studies centrifugal separation process optimization control technology, etc.Strengthening separation properties including drum rotational speed, In the process of centrifugal separation to add new impetus, Accelerating push slag speed, Increasing length of drum to extend the time of centrifugal separation etc. Development of large centrifuge, mainly is the drum drum diameter and by improving processing capacity of unit volume of material that processing equipment investment, energy consumption and reduce maintenance costs. The aspect of theory, the main research within the drum flow condition and cake formation mechanism, research and processing capacity of minimum separation of calculation methods.