The Technique of the Separation and Filtration


2016-08-16Tags:Filtration,Posted By Yolanda Cao

The Filtering and Separating Technology
1.The definition of the filtration
Filtration, by means of the filter medium, and Under certain pressure differential Δ P, the suspension liquid will enter into the solid supports or the filter medium duct, the solid particle will be diverted at the filter medium, then it finished the solid-liquid separation.
2.The Filtration related terms
Filter Medium, the filter usually use the porous mass
Filter Pulp, the suspension liquid which need to dispose
The Filtrate: The liquid which will help to through the porous passageway
The filter cake or the filter residue,: the solid mass which be diverted
3.The Filtration principle
(1)The fundamental of the Filtration
Filtration, by means of the filter medium, and Under certain pressure differential Δ P, the suspension liquid will enter into the solid supports or the filter medium duct, the solid particle will be diverted at the filter medium, then it finished the solid-liquid separation.
(2)The drives of the Filtration
The Gravity: The suspension liquid differential pressure
pressurized: the pressure that to the suspension liquid;
Decompression: the negative pressure caused by the vacuum force;
Centrifugal force: the inertial centrifugal force produced by the pivoting.
(3)The Filtration Resistance
Media resistance: it can be regarded as shielding, filters and generally more obvious early
Cake resistance:
Cake thickness - with increased filtration
Properties of the cake - particle shape and size.
In most cases, the filter cake resistance depends on the resistance

4 filtering methods
(1) according to the trapped particles
Depending on the amount of solid particles trapped in the medium to intercept suspension mechanism, the filter can be divided into two kinds.
1) on the surface of filtering
Suspension in medium side, solid deposit on the surface of the medium filter cake formation, it is also called filter cake filtration.
When the filtration start, the small particles will be through the filter medium, as progress through the filter, the smaller particles will be formed on the surface of the filter medium "bridging" phenomenon, gradually formed filter cake (residue)
In the surface of filter, when the filter cake to a certain thickness, the 'filter media' will play the main role.
It suitable for the suspending liquid filtration separation which solid content more than 0.1%
2) depth filtration
The Solid particles that separated can not form the filter cake formation, but the deposit on the thicker granular bed inside the filter medium.
The characteristics of the depth filtration is that the deposition of solid particles in thicker granular filter medium without particle layer formation on the surface of bed inside the filter medium.
Due to suspension of particles diameter is less than the bed channel diameter, when the liquid through the winding channel, the particles will flue into the medium pore together with the fluid, adhesion in the process of flow in the channel walls, applicable to suspension of particles is very small and little content of the system.
(2 )according to the filter driver
According to the driving force of the filter conditions are difference, the filter can be divided into three types: normal pressure filter, pressure filtration, and the Reduced pressure filtration:
1)Atmospheric pressure filtering: based on level difference filtering method of driving force. Laboratory commonly used filters and hanging basket or punching bag filter used in the production belong to the normal pressure filtration.
2) pressure filtration: it is the compressed air with a pressure pump or the pressure as the driving force for filtering method.
3) reduced pressure filtration, also known as vacuum filter or filter, is through the filter medium under vacuum method, in order to increase the pressure differential between the filter medium above and below, push the liquid through the filter medium, and large particle entrapment filtering methods