This document discusses various types of industrial filtration processes. It begins by defining filtration and clarification. It then covers the mechanisms of filtration, including straining, impingement, entanglement, and attractive forces. It describes types of filtration like surface filtration and depth filtration. Theories of filtration are discussed, including Poiseuille's equation, Darcy's equation, and the Kozeny-Carman equation. Factors influencing filtration and different pressure and vacuum filtration methods are also summarized, such as plate and frame filters, leaf filters, automatic belt filters, chamber filter presses, and vacuum filters.
Asymmetric synthesis (As per new syllabus of PCI)
Methods of asymmetric synthesis using chiral pool
Chiral auxiliaries and catalytic asymmetric synthesis
Enantiopure seperation
Stereoselective synthesis
Recent advances
References
Asymmetric synthesis (As per new syllabus of PCI)
Methods of asymmetric synthesis using chiral pool
Chiral auxiliaries and catalytic asymmetric synthesis
Enantiopure seperation
Stereoselective synthesis
Recent advances
References
Extraction
Various methods
Extraction with reflux
Extraction with agitation
Counter current extraction
reserve percolation process, continuous hot percolation process
decoction
infusion
digestion
Extraction with agitation
Maceration with adjustment
OXIDATION [PHARMACEUTICAL PROCESS CHEMISTRY]Shikha Popali
INTRODUCTION TO OXIDATION , WHICH IS PROCESS OF ADDITION OF OXYGEN TO THE COMPOUND IN RPOCESS CHEMISTRY AND LIQUID PHASE OXIDATION AND OTHER OXIDISING AGENTS ARE DISCUSSED.
UNIT OPERATIONS (unit 2) pharmaceutical process chemistrySaketChoudhary13
its a presentation on the 2nd unit of pharmaceutical process chemistry which include extraction ,filtration and steam distillation and azeotropic distillation
APIT, OPTIMISATION ,SCALE UP ,WORK UP, GREEN CHEMISTRY ,MSSDS, SOLVENT SELECTION, EFFLUENT TREATMENT AND MINIMISATION ,HEALTH HAZARD AND SAFETY HAZARD, IN PROCESS CONTROL
Ion exclusion chromatography is a technique,introduced by Wheaton and Bauman, used to separate ionic compounds from non-ionic compounds and to separate mixtures of acids.
The studies influence techniques of filtration, its various types, and theories involved in the rate of filtration. This topic useful for physical pharmacy students and other concerned with filtration.
Extraction
Various methods
Extraction with reflux
Extraction with agitation
Counter current extraction
reserve percolation process, continuous hot percolation process
decoction
infusion
digestion
Extraction with agitation
Maceration with adjustment
OXIDATION [PHARMACEUTICAL PROCESS CHEMISTRY]Shikha Popali
INTRODUCTION TO OXIDATION , WHICH IS PROCESS OF ADDITION OF OXYGEN TO THE COMPOUND IN RPOCESS CHEMISTRY AND LIQUID PHASE OXIDATION AND OTHER OXIDISING AGENTS ARE DISCUSSED.
UNIT OPERATIONS (unit 2) pharmaceutical process chemistrySaketChoudhary13
its a presentation on the 2nd unit of pharmaceutical process chemistry which include extraction ,filtration and steam distillation and azeotropic distillation
APIT, OPTIMISATION ,SCALE UP ,WORK UP, GREEN CHEMISTRY ,MSSDS, SOLVENT SELECTION, EFFLUENT TREATMENT AND MINIMISATION ,HEALTH HAZARD AND SAFETY HAZARD, IN PROCESS CONTROL
Ion exclusion chromatography is a technique,introduced by Wheaton and Bauman, used to separate ionic compounds from non-ionic compounds and to separate mixtures of acids.
The studies influence techniques of filtration, its various types, and theories involved in the rate of filtration. This topic useful for physical pharmacy students and other concerned with filtration.
Objectives, applications & Theories in FILTRATIONAkankshaPatel55
Filtration is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as oversize and the fluid that passes through is called the filtrate. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as blinding. The size of the largest particles that can successfully pass through a filter is called the effective pore size of that filter.
Filtration is used in many different applications, including:
Water treatment: to remove impurities from water, such as sediment, bacteria, and viruses.
Air filtration: to remove dust, pollen, and other allergens from air.
Oil filtration: to remove impurities from oil, such as dirt, metal shavings, and water.
Chemical processing: to separate solids from liquids in chemical reactions.
Food and beverage processing: to clarify liquids, such as juice, wine, and beer.
There are many different types of filters, each with its own advantages and disadvantages. Some common types of filters include:
Depth filters: These filters are made of a thick layer of material, such as paper, cloth, or sand. The solid particles are trapped in the pores of the filter medium.
Surface filters: These filters are made of a thin layer of material, such as a membrane. The solid particles are trapped on the surface of the filter medium.
Cartridge filters: These filters are self-contained units that can be easily replaced.
Bag filters: These filters are made of a bag of fabric that is suspended in a housing. The solid particles are trapped in the fabric of the bag.
It may be define as a process of separation of solids from a fluid by passing the same through a porous medium that retains the solids but allows the fluid to pass through.
When solid are present in very low concentration, i.e., not exceeding 1.0% w/v, the process of its separation from liquid is called clarification.
Filtration is any of various mechanical, physical or biological operations that separate solids from fluids by adding a medium through which only the fluid can pass. The fluid that passes through is called the filtrate.
explained about
Factors Affecting Filtration
Rate of filteration
Filter media
Classification of filter media
Industrial filters
A- Gravity filters. B- Vacuum filters
C- Pressure filters. D- Centrifugal filters.
Designing of aseptic area and laminar flow equipment.pdfPuja Ramu Basule
explanation about laminar air flow and aseptic area unit 4 pharmaceutical microbiology bpharmacy 3rd semister year-2022/2023 college name-gondia college of pharmacy, chulod
aseptic area designing and its layout with proper diagramatic explanation laminar air flow equipments picture- horizontal laminar air flow and vertical laminar air flow the material which we used in aseptic area like floors ,ceiling material and doors ,window etc
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New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
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Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
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TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
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Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
3. Definition
• Filtration
It may be define as a process of
separation of solids from a fluid by
passing the same through a porous
medium that retains the solids but
allows the fluid to pass through.
• Clarification
When solid are present in very low
concentration i.e. not exceeding
1.0% w/v, the process of its
separation from liquid is called
clarification.
5. Mechanism of Filtration
Straining Impingement Entanglement Attractive Forces
Similar to sieving
i.e. particles of
larger size can’t
pass through
smaller pore size of
filter medium.
Solids having the
momentum move
along the path of
streaming flow and
strike (impinge) the
filter medium. Thus
the solids are
retained on the filter
medium.
Particles become
entwined (entangled)
in the masses of
fibers (of cloths with
fine hairy surface or
porous felt) due to
smaller size of
particles than the
pore size. Thus
solids are retained
within fiber medium.
Solids are retained
on the filter
medium as a result
of attractive force
between particles
and filter medium,
as in case of
electrostatic
filtration.
6. Types of Filtration
Surface/screen filtration
It is a screening action by which
pores or holes of medium prevent
the passage of solids
Mechanism involved: straining and
impingement
For this, plates with holes or woven
sieves are used
Efficacy is defined in terms of
mean or maximum pore size
Depth filtration
In this slurry penetrates to a point
where the diameter of solid
particles is greater than that of the
tortuous void or channel
Mechanism: Entanglement
The solids are retained with a
gradient density structure by
physical restriction or by
adsorption properties or medium
7. Theories of Filtration
The flow of liquid through a filter follows the basic rules that govern the
flow of any liquid through the medium offering resistance
The rate of flow may be expressed as-
Rate= driving force/resistance
The rate of filtration may be expressed as volume(liters) per unit time(dv/dt)
Driving force=pressure upstream – pressure downstream
Resistance is not constant
It is increase with an increase in the deposition of solids on the filter medium
Therefore filtration is not a steady state
8. The rate of flow will be greatest at the beginning of filtration process, since
the resistance is minimum
After forming of filter cake, its surface acts as filter medium and solids
continuously deposit adding to thickness of the cake
Powder or granule bed visualized as a bundle of capillaries
Upstream pressure, P1
Surface area
Length (L)
Downstream
pressure, P2
Viscosity flow
rate: m3/unit time
Fig.: Filtration process parameters
Resistance to flow is related to several factors given in fig.
Resistance to movement=(pressure upstream – pressure downstream)/length of capillaries
9. Poiseullie’s Equation
Poiseullie considered that filtration is similar to the streamline flow of liquid under
pressure through capillaries
Poiseullie’s Equation is-
V=
𝞹∆𝑃𝑟4
8𝐿η
Where, V= rate of flow, 𝑚3
/s (l/s)
∆ 𝑃= Pressure difference across the filter, Pa
r= radius of capillary in the filter bed, m
L= thickness of filter cake (capillary length), m
η=viscosity of filtrate, Pa.s
If the cake is composed of bulky mass of particles and the liquid flows through the
interstice, then flow of liquids through these may be expressed by this equation
10. Darcy’s Equation
Poiseullie’s law assumes that the capillaries found in the filter are highly irregular
and non-uniform
Therefore, if the length of capillary is taken as the thickness of bed, a correction
factor for radius is applied so that the rate is closely approximated and simplified
The factors influencing the rate of filtration has been incorporated into an equation
by Darcy, which is:
V=
𝐾𝐴∆𝑃
η𝐿
Where, K= permeability coefficient of cake, 𝑚2
A= surface area of porous bed (filter medium), 𝑚2
Other terms are same as previous equation
K depends on characteristics of cake, such as porosity, specific surface area and
compressibility
11. Permeability may be defined quantitatively as the flow rate of a liquid of unit
viscosity across a unit area of cake having unit thickness under a pressure gradient
of unity
This equation is valid for liquids flowing through sand, glass beds and various
porous media
This model is applied to filter beds or cakes and other types of depth filter
This equation is further modified by including characteristics of K by Kozeny-
Carman
12. Kozeny-Carman (K-C) Equation
Kozeny-Carman equation is widely used for filtration
V=
𝐴
η𝑆2 ×
∆𝑃
𝐾𝐿
×
𝜀3
(1−𝜀)2
Where, 𝜀=porosity of cake (bed)
S= specific surface area of particles comprising the cake 𝑚2
/𝑚3
K= Kozeny constant (usually taken as 5)
Other terms are same as previous equations
Limitations:
It does not consider the fact that depth of granular bed is lesser than the
actual path traversed by the fluid
The actual path is not same through out the bed, but it is sinuous or tortuous
13. Factors influencing filtration
Properties of solid Temperature
Objectives
Properties of solids in
slurry
Properties of liquids
• Particle shape
• Particle size
• Particle charge
• Density
• Particle size
distribution
• Rigidity or
compressibility
of solids under
pressure
• Tendency of
particle to
flocculate or
adhere together
• Density
• Viscosity
• Corrosiveness
• Rate of
formation of
filter cake
especially in
early stages of
filtration
• Whether the
solids or
liquid or both
are to be
collected
• Temperature
of suspension
14. Pressure Filtration
Pressure filters can apply a large pressure differential across the septum to give
economically rapid filtration with viscous liquids or fine solids.
Due to the formation of cakes of low permeability, many types of slurry require higher
pressure difference for effective filtration than can be applied by vacuum techniques.
Pressure filters are used for such operations.
However, high operational pressures, may prohibit continuous operation because of
the difficulty of discharging the cake while the filter is under pressure.
Example is plate and frame filter press, Filter press, leaf filters, automatic belt filters,
chamber filter pressure etc.
15. Principle:
According to Kozeny-Carman equation, rate of filtration is directly
proportional to the overall pressure drop across filter medium and filter
cake.
The most common method of obtaining a pressure difference is applying
pressure on the surface of the slurry i.e. pumping the slurry onto the filter.
However, in the early stages of filtration, pressure difference should be
less.
This is to prevent the pores of the filter medium from clogging or
plugging, which subsequently increases resistance to the flow.
16.
17. Advantages
1. Cakes are obtained with very low moisture content.
2. Cakes may be disposed and flattened in layers provided they are not thixotropic and
sufficiently stable to support a tractor.
3. Intensive soluble recovery or removal of contaminants from the cake may be
achieved.
4. Clean filtrates may be produced by recirculating the filtrate for 1-2 minutes or by
precoating if a clear filtrate is required right from the start.
5. Solutions may be polished to a high degree of clarity.
6. Except for Filter presses a gas tight construction may be provided.
7. Except for Filter presses it is possible to jacket the tanks with steam if heat
preservation is required. This is of particular importance for saturated brines.
8. The filter bodies and internals may be constructed from a wide variety of alloys
including synthetic materials for filter presses.
9. Pressure Filters are available in a wide level of automation from labor intensive
operator controlled up to fully automatic machines.
18. Disadvantages
1. Cloth washing is difficult and if the solids are sticky a 3 mm precoat
from diatomite or perlite is required. - This adds another step prior to
filtration and if not done carefully and a too thin precoat is formed it
may leave areas with exposed cloth which will blind rapidly.
Conversely, if a too thick precoat is formed since the operator seeks
to be on the safe side, such a precoat consumes effective cake
volume.
2. The operator can hardly see the forming cake and is unable to carry
out an inspection while the filter is in operation.
3. The internals are difficult to clean and this may be a problem with
food grade applications.
19. 1. Plate and Frame Filter Press
A filter press contains a set of plates designed to provide a series of chambers or
compartments in which solids may collect. The plates are covered with a filter medium
such as canvas. Slurry is admitted to each compartment under pressure; liquor passes
through the canvas and out a discharge pipe, leaving a wet cake of solids behind.
Construction
• Consist of plates and frames assembled alternately with a filter cloth over each side
of the plates
• The plates have channels cut in them so that clear filtrate liquid can drain down
along each plate
• The feed slurry is pumped into the press and flows through the duct into each of the
open frames so that slurry fills the frames
• The filtrate flows through the filter cloth and the solids build up as a cake on the
frame side of the cloth
20. • The filtrate flows between the filter cloth and the face of the plate though the channels of the
outlet
• The filtration proceeds until the frames are completely filled with solids
Fig. Filter press. Assembly of plates and frame
22. Working :
The slurry enters the frame
from the feed channel
The filtrate passes through the
filter medium on to the surface of
the plate while the solids form a
filter cake in the frame.
The filtrate then drained down
the surface of the plate , between
the projections on the surface and
escapes from the outlet.
Filtration is continued until the
frame is filled with filter cake,
when the process is stopped , the
frame emptied, and the cycle re-
started.
23. Advantages &disadvantages
Advantages:
1. Construction is very simple and a wide variety of materials can be used.
2. It provides a large filtering area in a relatively small floor space.
3. It is versatile, the capacity being variable according to the thickness of the frames
and the number used.
4. The construction permits the use of considerable pressure difference.
5. Efficient washing of the cake is possible.
6. Operation and maintenance is straightforward , because there no moving parts,
filter cloths are easily renewable and, because all joints are external, any leaks are
visible and do not contaminate the filtrate.
24. Disadvantages:
1. It is a batch filter, so it is a time consuming.
2. The filter press is an expensive filter, the emptying time, the labor
involved, and the wear and tear on the cloths resulting in high costs.
3. Operation is critical, as the frames should be full, otherwise washing is
inefficient and the cake is difficult to remove.
4. The filter press is used only for slurries containing less about 5 %
solids
25. 2. Leaf filters
• Filter leaf is an apparatus consisting of a longitudinal drainage screen covered with a
filter cloth. The mechanism is surface filtration and acts as sieve or strainer.
• The leaf filter was developed for larger volumes of slurry and more efficient washing
• Each leaf is a hollow wire framework covered by a sack of filter cloth
• A number of these leaves are hung in parallel in a closed tank
• The slurry enters the tank and is forced under pressure through the filter cloth, where
the cake deposits on the outside of the leaf
• The filtrate flows inside the hollow framework and out a header
• The wash liquid follows the same path as the slurry. Hence, the washing is more
efficient than the through wishing in plate-and-frame filter presses
26.
27. Construction
• The core of the leaf, whether round or rectangular is a piece of heavy,
coarse-mesh double-crimped wire screen.
• Often over this is a backing of finer screen, but still too coarse to act as a
filter medium.
• Around the outside edges of this assembly is a light piece of metal of U-
shaped cross section that binds the edges.
• To this binding is attached a discharge nipple that serves both to remove
filtrate and suspend the leaf.
• Over the leaf is drawn a sack of filter cloth, sewn tightly around the edge
of the leaf and caught under a collar around the discharge nipple.
28. • The nipple passes through a collar on the filter body and may be tightened by cap
nut.
• Gasket between the nipple and the inside of the filter shell and between the cap nut
and the nipple make tight joints.
• Connections between the nipple and the discharge manifold include valves and sight
glass, the latter being held between stuffing boxes.
• From the upper valve a connection leads to the discharge manifold.
29. 3. Automatic belt filter
It is a discontinuous pressure filter that separates, compresses, washes and
automatically discharges the cake.
Filtration takes place in from 2 to 20 horizontal chambers, set one above the
other.
A belt of filter cloth passes through the filter chambers in turn.
With the belt held stationary, each chamber is filled with solids during the
filtration cycle.
High pressure water is then pumped behind a flexible diaphragm in the chamber
ceiling, squeezing the cake and mechanically expressing some of the liquid.
With the diaphragm released, wash water may be passed through the cake and
the cake recompressed by the diaphragm if desired.
Finally air is blown through the cake to remove additional liquid.
30. Fig. Larox automatic pressure filter showing path of filter belt and mechanism of cake discharge.
31. 4. Chamber filter presses
Construction and working
o A heavy fixed head of cast iron is mounted on a suitable frame and has the
necessary pipe connections on it.
o Extending from this head are two horizontal bars, supported at the other end
by the end frame. These supports the plates of the press by lungs.
o In the center of each plate is a hole, which is in line with a connections on the
head of the press where the feed is introduced.
o Over each plate is thrown a sheet of filter cloth with a hole cut in the center to
register with the hole in the plate.
o The filter cloth is fastened to the plate at this point by means of rings, called
grommets, which either screw together or lock with a bayonet lock.
32. Lugs
Lugs
Feed
channel
Outlet
ports
Front elevation of plate and a typical section through along the line MM
o When all the plates have been so dressed, a heavy follower plate is placed
behind the whole assembly and the plates are pressed tightly together by
means of a heavy screw or a hydraulic pressure device.
o Under pressure the cloths are forced back against the face of the plate.
o When sufficient cake has accumulated to fill the chambers, the closing screw
is released, the follower is drawn back along the supporting rails, the plates
are drawn back, and the cakes discharged, one at a time.
33. Vacuum filtration
Filtration technique where suction is applied to the mixture of solid and liquid being
filtered so as to pull the liquid through the filter.
This technique is much faster than gravity filtration. Vacuum filtration usually involves
the use of a vacuum filter flask, a filter trap, a water pump, and either a Buchner funnel or
sintered glass crucible.
The liquid mixture is poured into the filter (Buchner or sintered glass), the liquid is
sucked down into the filter flask by the action of the water pump, and any excess liquid
that overflows out of the filter flask is caught in the filter trap. The solid matter is left on
the surface of the filter.
34. Principle:
The pressure underneath the filter medium may
be reduced below atmospheric pressure by
connecting the filtrate receiver to a vacuum
pump. This creates a pressure differential across
the filter.
In vacuum filters, the driving force for filtration
results from the application of suction on the
filtrate side of the medium. Although the
theoretical pressure drop available for vacuum
filtration is 100 kPa, =1 Kg/cm2 in practice it is
often limited to 70 or 80 kPa or even less.
35. Advantages:
1. Gravity settling can take place before the vacuum is applied. In many cases, this may prevent
excessive blinding of the cloth due to action of a pre-coat formed by the coarser particles.
2. Heavy or coarse materials can be filtered because if they settle out from the feed they do so onto the
filter surface.
3. Fine particle penetration through the medium can be tolerated because the initial filtrate can be
recycled back onto the belt.
4. Top-feed filters are ideal for cake washing, cake dewatering and other process operations such as
leaching.
5. A high degree of control can be exercised over cake formation. Allowances can be made for changed
feeds and/or different cake quality requirements. This is particularly true of the horizontal belt vacuum
filters. With these units the relative proportions of the belt allocated to filtration, washing, drying, etc.,
as well as the belt speed and vacuum quality, can be easily altered to suit process changes.
Drawbacks:
1. Such filters usually require large floor areas.
2. Their capital cost is high.
36. 1. The leaf filter:
-The leaf filter is consisting of a frame enclosing a drainage screen or grooved plate, the whole unite
being covered with filter cloth.
-The outlet for the filtrate connects to the inside of the frame, the general arrangement is shown in the
Fig. which represents a vertical section through the leaf. The frame may be circular, square or
rectangular shapes.
Working:
The leaf filter is immersed in the slurry and a receiver and a vacuum system connected to the filtrate
outlet.
Slurry passed through the filter cloth and finally filtrate enters the Drainage canal and goes through
outlet into the receiver.
Air is passed to flow in reverse direction which facilitates removal of cake
37. Advantages:
1- The slurry can be filtered from any vessel.
2-The cake can be washed simply by immersing the filter in a
vessel of Water.
3- Removal of the cake is facilitated by the use of reverse air
flow.
4- The filter can be modified by employing a suitable number
of unites.
5- The leaf filter is most satisfactory if the solids content of the
slurry is no too high, 5 % being a suitable maximum.
6- Labor costs for operating the filter are comparatively
moderate.
An alternative method is to enclose the filter leaf in a special
vessel into which the slurry is pumped under pressure. A
number of leaves are connected to a common outlet, to
provide a large area for filtration e.g. Sweet land filter.
39. Rotary vacuum filter (Rotary filter)
The most common type of continuous vacuum filter.
The rotary drum filter in which liquor is sucked through a moving septum to
deposit a cake of solids.
Cake is moved out of the filtering zone, washed, sucked dry and dislodged
from the septum.
Construction
1. It is consisting on a sheet metal drum.
2. A vacuum system is also attached.
3. The surface of the drum is the divided into different section by stripes.
4. Filter medium is hold by metal strips on drum and covered by filter cloth.
5. In each section there are many pipes which open inside the cover plates.
6. To remove the cake “Doctor knife” is provided.
41. Working
1. Before filtration rotary drum filter is dip in tank of
filter aid for precoating (e.g. diatomaceous earth,
perlite or purified wood cellulose).
2. Drum is rotated in slurry tank at a speed of 1 to 2
rpm. 1/3 of drum is dip in slurry tank and vacuum is
applied.
3. Cake formation.
4. As, the panel leave the cake formation zone it enters
to washing zone.
5. As, the panel leave the cake formation zone it enters
to washing zone.
6. Cake removed in cake removal zone.
42. Industrial Application
• These filter are developed to overcome large problem of filter
press and leaf filter. It is very versatile filter.
• It is used generally for those operation in which the volume is
very large.
• It is used where colloidal particles.
• It is used for production of wallboard from gypsum.
43. Advantages:
1- The rotary filter is automatic and is continuous in operation, so that the labor costs are
very low.
2- The filter has a large capacity , so it is suitable for the filtration of highly concentrated
solutions.
3- Variation of the speed of rotation enables the cake thickness to be controlled.
4- Pre-coat of filter aid could used to accelerate the filtration rate.
Disadvantages:
1- The rotary filter is a complex piece of equipment , with many moving parts and is
very expensive,.
2- In addition to the filter itself, some accessories are connected , e.g, a vacuum pump,
vacuum receivers , slurry pumps and agitators are required .
3- The cake tends to crack due to the air drawn through by the vacuum system, so that
washing and drying are not efficient.
4- Being a vacuum filter, the pressure difference is limited to 1 bar and hot filtrates may
boil.
5- It is suitable only for straight- forward slurries.
44. 3. Discontinuous vacuum filters
• A discontinuous vacuum filter, however, is sometimes a useful tool.
• A vacuum nutsch is little more than a large Buchner funnel, 1 to 3m (3-10 ft)
in diameter and forming a layer of solids 100 to 300 mm (4-12 in.) thick.
• Because of its simplicity, a nutsch can readily be made of corrosion-resistant
materials and is valuable where experimental batches of a variety of
corrosive materials are to be filtered.
• Nutsches are uncommon in large-scale processes because of the labor
involved in digging out the cake; they are, however, useful as pressure filters
in combination filter-dryers for certain kinds of batch operations.