Etiket Arşivleri: Filtration

Filtration ( Dr.Öğr.Üyesi Salih KARASU )

FILTRATION

The filtration process is described by the manner in which the fluid being filtered flows through the filter medium where the solids are deposited.

As the solids are removed from the fluid, they accumulate in the filter medium, resulting in an increased resistance to flow as the filtration process continues. All these factors result in a description of filtration rate

Filtration

Filtration involves the removal of insoluble particles from a suspension by passing it across a porous material, retaining particles according to their sizes and shape to some extent.

As the filter media retain the larger particles and form a “filter cake”, the permeate passes through the filter barrier.

The mean size particles and their distribution will both have a great influence on the type of filter used.

Filtration equipments are mainly used in edible oil refining, sugar refining, beer production, wine making, and fruit juice processing.

The uses of Micro filtration (MF) and ultra filtration (UF) for those latter applications are increasing, as more efficient industrial equipment and membranes become available

Plate frame filters

Plate frame filter press

Horizontal plate filters

Drum filter

Filter aids

Filtration aids, such as diatomaceous earth, cellulose or charcoal, are often used as absorbents to control the formation and the properties of the filter cake, in order to prevent resistance to fluid flow

Source: http://avesis.yildiz.edu.tr/skarasu/dokumanlar

Separation Methods

Separation Methods

Ways to separate mixtures – Chapter 3: Matter & Its Properties

How do we separate …?

Separating Mixtures

Substances in a mixture are physically combined, so processes bases on differences in physical properties are used to separate component

Numerous techniques have been developed to separate mixtures to study components

Filtration

Used to separate heterogeneous mixtures composed of solids and liquids

Uses a porous barrier to separate the solid from the liquid

Liquid passes through leaving the solid in the filter paper

Distillation

Used to separate homogeneous mixtures

Based on differences in boiling points of substances involved

Crystallization

Separation technique that results in the formation of pure solid particles from a solution containing the dissolved substance

As one substance evaporates, the dissolved substance comes out of solution and collects as crystals

Produces highly pure solids

Rocky candy is an example of this

Centrifuging

A magnet

Can be used to separate a magnetic substance from a non-magnetic substance

Chromatography

Separates components of a mixture based on ability of each component to be drawn across the surface of another material

Mixture is usually liquid and is usually drawn across chromatography paper

Separation occurs because various components travel at different rates

Components with strongest attraction for paper travel the slowest

Decantation

Decanting is done to separate particulates from a liquid by allowing the solids to settle to the bottom of the mixture and pouring off the particle-free part of the liquid. Another method is to allow two immiscible liquids to separate and the lighter liquid is poured off.

Sieving

a porous material is used to separate particles of different sizes.

method is most commonly used to effect gross separations, as of liquids from suspended crystals or other solids.

to accelerate filtration, pressure usually is applied.

a series of sieves is stacked, with the screen of largest hole size at the top


Filtering

ABSTRACT

Filtration is a physically or mechanically separation process in which suspended solid particles in a fluid are removed by using a porous medium that retain the particles as a cake and passes the clear filtrate. The model considered filtration that occurs after the filling process, not filtration that occurs as the suspension fills the cell. Operational equations and theoretical calculation K, s, C, m were developed for a plate-and-frame press.

PURPOSE

In this experiment, our aim was to gain an experience about how filtration process goes on and then to be able to determine the constants and such equations for hat process.

Filtration

Filtration is a mechanical or physical operation which is used for the separation of solids from fluids (liquids or gases) by interposing a medium to fluid flow through which the fluid can pass, but the solids (or at least part of the solids) in the fluid are retained. It has to be emphasized that the separation is NOT complete, and it will depend on the pore size and the thickness of the medium as well as the mechanisms that occur during filtration.

 Filtration is used for the purification of fluids: for instance separating dust from the atmosphere to clean ambient air.

 Filtration, as a physical operation is very important in chemistry for the separation of materials of different chemical composition in solution (or solids which can be dissolved) by first using a reagent to precipitate one of the materials and then use a filter to separate the solid from the other material(s).

 Filtration is also important and widely used as one of the unit operations of chemical engineering.

It is important not to confuse filtration with sieving. In sieving there is only a single layer of medium where size separation occurs purely by the fact that the fraction of the particulate solid matter which is too large to be able to pass through the holes of the sieve, scientifically called oversize are retained. In filtration a multilayer medium is involved, where other mechanisms are included as well, for instance direct interception, diffusion and centrifugal action, where in this latter those particles, which are unable to follow the tortuous channels of the filter will also adhere to the structure of the medium and are retained.

Depending on the application, either one or both of the components may be isolated. The filtration process separates particles and fluid from a suspension, and the fluid can be either a liquid or a gas (or a supercritical fluid). To separate a mixture of chemical compounds, a solvent is chosen which dissolves one component, while not dissolving the other. By dissolving the mixture in the chosen solvent, one component will go into the solution and pass through the filter, while the other will be retained. This is one of the most important techniques used by chemists to purify compounds.

Filtration also cleans up water streams or other river streams. Furnaces use filtration to prevent the furnace elements from fouling with particulates. Pneumatic conveying systems often employ filtration to stop or slow the flow of material that is transported, through the use of a bag house.

Filtration By Frame and Filter Press

Filtration (liquid) is the separation of solid from a fluid by means of a porous medium that

retains the solid but allows the fluid to pass.

OBJECTIVES

 To study the filtration processes by a frame and filter press

 To determine the flow rate through the filter

 To determine specific cake resistances and filter medium resistance for a number of

constant pressure runs

Filtration v2

The filtration process of mint in water was done by using plate–frame filter that consist of 4 frames at0,4 bar and 0,9 bar pressure. Slurry entered at one end of the assembly of plates and frames. It passed through a channel running lengthwise through one corner of the assembly. Auxiliary channels carried slurry from the main inlet channel into each frame. Here the black pepper particles were deposited on the cloth covered faces of the plates. Liquor passed through the cloth, down grooves or corrugations in the plate faces, and out of the press. Filtration is a kind of separation method which is widely used in food industry. In fruit juice industry, to clarify fruit juice, filtration is applied. Moreover, filtration is applied for clarifying vinegar, beer, wine, brines and sugar syrups. And also refining of edible oils contains filtration process. For example, crude oils contain some impurities such as gums.

These impurities are removed by filtration. Shortly degumming, decolorization and winterization of oils are the applications of filtration in oil industry. In addition during the hydrogenation of oil, nickel is used to speed up the reaction, after reaction, nickel catalyst is removed by filtration There is not so many deviations in the experimental results when considering the normal plate-frame filtration procedures. Similar results were obtained from this experiment when the general constant filtration results are examined. The volume of filtrate was decreased and this caused a positive slope of PQ/V vs. V graph.

In filtration the liquid passes through two resistances in series; that of the cake and that of the filter medium. The filter-medium resistance, which is the only resistance in clarifying filters, is normally important only during the early stages of cake filtration. The cake resistance is zero at the start and increases with time as filtration proceeds (W. McCabe, J. Smith and P. Harriot, 1987, Unit Operation Of Chemical Engineering). In the experiment, the cake resistance of mint increased with time and it reduced the volume of filtrate.

The intercept points of the graphs confirmed the predicted values due to suitable initial flow rates. Since the viscosity of water is not high, the viscosity of fluid was not problem for filtration. After assembly of the press, slurry is admitted from a pump or blow case under a pressure of 3 to 10 atm (G. Brennan et al., 1976, Food Engineering Operations). The applied pressure was low to exercise the industrial filtration procedure when considering this statement. At higher constant pressure the time to remove more filtrate is smaller; this is another result that takes attention.

Plate and Frame Filters

Filtration is a physically or mechanically separation process in which suspended solid particles in a fluid are removed by using a porous medium that retain the particles as a cake and passes the clear filtrate. The porosity distribution and filtrate production during cake filtration in a plate-and-frame filter press were simulated mathematically. The model considered filtration that occurs after the filling process, not filtration that occurs as the suspension fills the cell. Operational equations and theoretical calculation K, s, C, m were developed for a plate-and-frame press.

Plate and Frame Filtration

The porosity distribution and filtrate production during cake filtration in a plate-and frame filter press were simulated mathematically. The model considered filtration that occurs after the filling process, not filtration that occurs as the suspension fills the cell. Governing equations for the temporal porosity distribution were developed for a plate and- frame press. The governing equations were solved numerically. Appropriate initial and boundary conditions were determined based on characteristics of the plate-and-frame press and of the suspension properties

The purpose of this experiment was to learn how plate-and-frame filtrate machine to work and also to determine the filtration constants of K, s, C, m. This experiment was done at two different and constant pressures filtration constants were found by plotting theVP/vs. Vgraph for run 1 and run 2.