drilling fluids decanting centrifuge

Basic Principles

The solid drum is internally installed with a concentric discharge screw As they rotate in the same direction at a high speed, They have a certain rotational speed difference, which is caused by the driving system and the differential case Suspension enters the internal of the charge screw through the speed pipe and then goes into the drum after being accelerated Under the centrifugal force, solid particles of big density settle on the inwall of the drun, and form a circular layer of cake, which is continuously pushed by the discharge screw to the small end of the drum end then out of it, while the set:led liquid is continuously discharge out of the drum from the vortex finder of the big end of the drum, hence solid-liquid sparation of suspension.
Basic Principles
For the decanter centrifuge, the continuous feeding separating and discharging can be realized as it rotates at its full speed. It is characterized by compact structure easy obturation smith running, low noises, large handing capacity, low energy consumption, high automation small working strength, simple operation and easy maintenance and wide application. 
Application scope
The decanter centrifuge is suitable for solid-phase dewatering, liquid-phase clarification and separation, liquid-liquid-solid three phase separation and size-grading of various suspensions with solid-phase particle sizes of 0.005-15mm, consistency of 1-40% and temperature of ≤ 100°C, esp. for separatong the suspensions whose consistency and particle size vary greatly and for which recovery of filter cloth is difficult, such as treatment of PVC resins, ammonium sulfite, barrium carbonate, strontium sulphate, lithopone,starch, diatomite, plaster, bauxite, soybean protein, peanut protein, fruit juice, drinks, vegetable oil, citric acid, powder of blood, powder of titanium white, kaolin clay and drilling mud, etc., and dewatering of washed coal and fine coal, purification of waste oil, treatment of grain stillage liquid waste and municipal sewage and mineral classification. Besides, it is suitable for waste water treatment of electric power plant sludge, printing and dyeing sludge, paper manufacture sludge.

1,The manufacture and design accord with the standard Of “JB/T502-2004 Decanter Centrifuge” and“JB 8525-1997 Safety Requirements of Centrifuge”. High rotational speed,high separating factor and big lenth-to-diameter ratio.For centrifuges with drum diameter below 530mm,their separating rotational speed is usually above 3000r/min,their separating factor is above 2500 and their length-to-diameter ratio can reach up to 5.Among them,the highest rotational speed of LW250X1000-N can reach 5400r/min,and its separating factor iS above 4000.

2,Big single machine processing capacity:The decanter centrifuge series with diameters of 250,300,355,400,450,500,530, 580,650,760 and 900,10000(mm)are all designed according to the newest fluid theory and with reference to the advanced structures abroad.they have a big capacity and fine separatine effect.

3,Low vibration,low noises and big bearing capacity.Imported main bearings with high precision and big bearing capacity are used for this series,Precision of components is high.The entire machine gets precise dynamic balance through dual rotors,thus stationarity and reliability are guaranteed when it is running at a high rotational speed.With low vibration and loW noises,all of its properties are higher than those stipulated in the NationaI Standard.

4,With multiple protecting apparatus,reliable running is realized.The senes of centrifuges are usually equipped with such overload protective devices as differential case or torque-limiter coupling.If required,other protection devices such as vibration protection,temperature monitoring and protection,and feed adjusting,etc.can be equipped,which are able to protect the entre machine by automatic alarm and forced stoppage. 

5,Property Of dfferential system is reliable,Differential case Of satellite differential Or cycloidal needle wheel differental is used.if necessary,fully hydraulic dfferential system is used.Mechanial dfferential cases Of well-known natlonal brands have been chosen,and hydraulic pressure differential system adopts the foreign brands.The differential case is of high precisiOn,high performanceand reliable Operation.

6,Key parts are corrosion-resistant and wear resistant. The surface of screw, the inlet on* the svrew and the dischange outlet on drum are usually surfaced or beadweld with wear-resistant surface made of hard carbide. For the centrifuges on special ossasions, wear-resistant blocks of imbedded hard carbide are adopted, or inlaid with wear resistant jacket or wear resistant ceramic plates, corrosive-resistant, wear-resistant and lasting.

7,It has many modes of drive and speed regulation. According to different demands, corresponding drive, differential and speed regulation mode can be adopted to adjust the rotate speed of drum and its differential rotate speed so as to achieve the best separating results on different separating occasions.

8,Fine obturation and explosion-proof performance. Machines of obturation and explosion-proof type are specially designed for those special separating occasions inflammable and explosive. Mechanical seal can last no fewer than 8000 hours and gas seal no fewer than 15000 hours.

9,Advanced and reliable control system of electrical system equipment. Types of control of electrical equipment can be classified as conventional, explosion-proof and fully automatic control with computers. CDS centrol control system can also be selected for remote supervisory and controlling and full-automatic operation. All the electrical compinents of the electrical control system are either imported from abroad or of famous brands at home, which perform well. 

10,Meterials of high quality have been used. Austenitic stainless steel or two-phase stainless steel is usually used for the parts of machines that suspension touch. These parts have high strength and good ability to resist corrosion.

Typical structures of the decanter centrifuge  

Counter-current type After blended liquid flows into drum, the cleaned solution and the cake move conversely in separating, each flowing toward its own outlet. The counter current type is a king of normal one and suitable for most separating situations.

Co-current type After blended liquid flows into drum, the cleaned solution and the cake move in the same direction when separating, after separation, the cleaned solution flows back and is discharged through backfiow connection in order that cake is not washed away by feed liquid when feedng. This rye is more suitable for separation of materials witn Iow concentration and difficult to separate. 

Three phase separstion type After two liquid phases and one solid phase with differential density come in to drum, under a centrifugal force, solid phase settles and the two liuquid phases are stratified, thus liquid-liquid-solid separation is realized. This type is suitable for such a three-phase separation situation as liquid-liquid-solid with differential density.  

Drive and speed regulation of decanter centrifuge series

Driven by a single-speed motor and the onput the stalk of differential case is fixed-Adjust the roate speed of the drum and differential rotate speed by changing belt pulley, which is suitable for separation of common materials that de not have any special changes.
Control drive of the main motor and the auxiliary motor respecticely with two frequency-converters, and the drive ratio of the differential case is fixed. It is fast to control drive of the main motor and the auxiliary motor and adjust the rotate speed of the drum and differential rotate speed respectively with two frequency-converters. 
Main motor drivers drum, and differential speed is regulated by hydraulic motor Regulate rotate speed of drum driven by main motor by using frequency-conversion speed governor’ and change rotate speed by using hydraulic motor 
Relationship between different kinds of roate speed and the differential roate speed between drum and discharge screw
Rotate speed of drum: nr=n1 x il
nr--rotate speed of drum r/min
n1--rotate speed of main motor(The rotate speed of the main rotator is indicated on its nameplate or adjusted and set by frequency-conversion speed-regulation modes.)r/min
i1--drive ratio of main motor with the drive of drum belt pulley 
differential rotate speed of drum with discharge screw: n=(nr-nd) 4/id =(nl x i1- n2 x i2) / id
n--differential rotate speed of drum with discharge screw r/min
id--fixed drive ratio of differential case
n2--rotate speed of auxiliary motor(The rotate speed of the auxiliary rotator is indicated on its nameplate or adjusted and set by frequency-conversion speed-regulation modes.)r/min
i2--drive ratio of auxiliary motor with the drive of differential case belt pulley
When a hydraulic motor or a fully hydraulic motor differential mechanism is adopted, the rotate speed of discharge screw is set up directly by the hydraulic motor or the fully hydraulic motor differential mechanism,and the differential rotate speed of drum with discharge screw is the liquid presses the motor exportation to turn soon.

ecomposition of key parts of decanter centrifuge
The solid drum is internally installed with a concentric discharge screw As they rotate in the same dJreotion at a high speed, They have a certain rotational speed difference, which is caused by the driving system and the differential case Suspension enters the internal of the charge screw through the speed pipe and then goes into the drum after being accele rated Under the centrifugal force, solid particles of big density settle on the inwall of the drun, and form a circular layer of cake, which is continuously pushed by the discharge screw to the small end of the drum 8nd then out of it, while the set:led liquid is continuously discharge out of the drum from the vortex finder of the big end of the drum, hence solid-liquid sparation of suspension.

Drum                                             Discharge screw                    Satellite

Drum cover