FILTRATION & SEPARATION

CONTENTS

I. FILTERS

II. COALESCERS

III. MEDIA DEPTH FILTERS- Filtration- Adsorption

I. FILTERS

Under Sized

Fine Particles

RETAINED

FTLTRATEFEED

Over Sized

Coarse Particles

Filtration commonly refers to the mechanical operation of separation of solid particles (contaminants) from the fluids by interposing a filter media through which the fluids pass but solid particles of targeted sizes do not.The physical state of the fluid can either be gaseous or liquid, and in this field where we design filters of pressure vessel type, the fluids are pressurized.

TYPES OF FILTERS

DEPTH TYPE SURFACE TYPE

WOUND FILTER

Well known as a Wound Depth type or String Wind type Nominal filter,the winding pattern covers the entire depth of the filter tube with hundreds of funnel shaped tunnels which become gradually finer from the outer surface to the center of the tube and trap progressively finer particles as the fluid travels to the center.This allows much greater solids retention capacity than is associated with surface filter media of the same dimensions. Variety of material selection enables wide range of its application.

PLEATED FILTER

Pleated Cartridges have significantly larger Surface Area compared to the Non-Pleated Cartridges.Cartridges with larger Surface Area will have a lower flux rate (m3/hr / m2 = m/hr) across the filter element than those with less Surface Area for the same given flow rate.As the Lifetime of the filters is inversely proportional to flux, Pleated Cartridges provide longer life with higher Dirt Holding Capacity.

CALCULATION OF THE SURFACE AREA

Non-Pleated

Pleated

Given Condition1. Diameter : 114.3 mm2. Length : 1016 mm

Diameter x π(3.141592..) x Length=114.3 x 3.141592 x 1016 = 0.364 m2

Given Condition1. Diameter : 114.3 mm2. Length : 1016 mm3. V Pleat Count : 25 EA4. V Pleat Length : 24.5 mm

VPL x 2 Faces x VP Count x Length= 24.5 x 2 x 25 x 1016 = 1.245 m2

x3.5 times larger Surface Area!

PLEATED FILTER

RADIAL PLEAT

Compound Radial Pleat design maximizes usable media surface area.

Surface Area can be up to 10m2 per 40”L Cartridge.

MESH FILTERTYPES

Main Mesh

Support Mesh

(Optional)

Support Mesh

(Optional)

Perforated Plate

Pleated

Cartridge

Non-Pleated

Cartridge

Basket Filter

& Strainer

MESH FILTER

Elements of Mesh Cartridge Filter and Basket Filter/Strainer have basically the same structure;

Mesh Element for Filtration and Perforated Plate for its support.

The only difference is the Flow Direction;

- Cartridge : from Out to In(Perforated Plate supports the inner surface of the mesh)

- Basket : from In to Out (Perforated Plate is on the outer surface)

Non-Pleated Pleated Basket

Basket Strainers can fundamentally be classified into 2 categories, considering the Elevation of the Inlet Nozzles and the Outlet Nozzles ;

B-120 type would have a Flat Horizontal Basket Flange, which divides the upper part with Inlet Nozzle, and the lower part with the Outlet Nozzle.

B-130 type would have a 45 Degree-Angled-Face for the same elevation of the Inlet Nozzle and the Outlet Nozzle, which would be ideal for a in-line filter.

BASKET STRAINER

B-120 B-130

SCREEN FILTER

Plane Support Grid

Unlike Mesh, there are only 2 contact points to retain particles, and the tapered flow paths prevent clogging, resulting in constant low pressure drop.

The distance between surface profiles is called “Slot” and this Slot filters solid particles in the flow.

Particles that can enter the path will pass through, and the ones that fail to pass may fall off or can be scraped off the surface.

Cartridge Type: Out to In Flow

Basket Type: In to Out Flow

SINTERED FILTER

In addition to Mesh Filters there are other Metal Filters such as Sintered Fiber Filters and Sintered Powder Filters that can be constructed of Stainless Steel, Duplex Stainless Steel or other metallic components.

Sintered Metal Fiber Filters of a non-woven sintered cloth media, are of fine Metal Fibers ranging from 0.25 to 100 microns. While Mesh Filters provide Surface Filtration, Sintered Metal Fiber Filters have both Surface and Depth Filtration performance with higher Dirt Holding Capacity, enabling longer life cycle.

Sintered Metal Powder Filters are most appropriate for finest particle filtration, as the micron rating ranges from 0.1 to 200 microns.

This will be available in Non-Pleated type only.

While the element of the Basket Filters/Strainers is of Cleanable Mesh, Bag Filters have Disposable type elements for easy replacement and maintenance.

Basket Filters/Strainers and Bag Filters share the common characteristics of their structures of having Perforated Plate supports on the outer surface of the filter element.

BAG FILTER

Ceramic Filters aren’t that frequently used filter media, but it can be used in a number of applications where the process requires severe conditions such as Operating Temperature up to 800℃ (1400℉) or Differential Pressure Drop up to 35 bar (500 psid), such as smelting, cremation or chemical manufacture.

For both Gaseous and liquid can the Ceramic be applied and its Micron Ratings and Filtration Efficiency can be as per the table below;

CERAMIC FILTER

Fluid Micron Ratings Efficiency

Liquid 0.25, 1, 3, 6, 15, 26, 35, 50, 60, 90… 98%

Gaseous 0.03, 0.1, 0.4, 0.8, 2, 3, 4, 6, 8, 11… 99.9%

STRAINER

The basic structure of Strainers is the same as that of the Mesh Type Basket Filters;Having structure of Mesh as the filtering element and the Perforated Plate as its support adopted for the Surface Filtration.

Required Filtration Efficiency will generally be less than 300 mesh, which is considered equivalent to approximately 50 microns.As its purpose is to remove coarse particles, most of the times, the requirement will be around 40~80 Mesh.

In case the Housing (Body) of the Strainer is of a Casting or a Forging material, which is a ready-made stock product, the Efficiency of the Mesh shall be considered with extra caution.As the Mesh Count Numbers increase, the Open Ratio (Open Area of the Surface Area of Mesh to the Section Area of the Inlet Nozzle) are likely to decrease according to the Diameter of the Mesh Wire. At least 200%, or 300% preferably, of the Open Ratio shall be considered. Otherwise the elements shall be cleaned more often, as the clogged particles will cause high pressure drop frequently.

* More details are available on the “DESIGN NOTE“ of the Basket Filters.

DESIGN NOTE

A) FILTRATION EFFICIENCY

1. Absolute Ratingrefers to the diameter of the largest spherical solid particle which can actually pass through the filter.Generally, its efficiency can be stated as any value between 99%~99.99%.

2. Nominal Rating

refers to the removal rate of an acceptable statistical amount of solid particles of a certain size.

Generally, its efficiency can be stated as any value between 90%~98%.

3. BETA() Ratio

The definition “Absolute” and “Nominal” is not of the universal concept, and is not uniformly defined, the performance of filters of the same ratings can differ significantly.

In this case, BETA() Ratio can be used to determine the solid particle removal efficiency :

Efficiency = (1-(1/)) x 100

5≥10 = 5㎛ @ (1-(1/10)) x100 = @90%

5≥50 = 5㎛ @ (1-(1/50)) x100 = @98%

5≥100 = 5㎛ @ (1-(1/100)) x100 = @99%

5≥200 = 5㎛ @ (1-(1/200)) x100 = @99.5%

5≥1000 = 5㎛ @ (1-(1/1000)) x100 = @99.9%

5≥10000 = 5㎛ @ (1-(1/10000)) x100 = @99.99%

It can be translated that targeted micron rating to be filtered is 5㎛ for this filter, and 10 out of 100 5㎛ particles will pass through the filter element, and 90 out 100 are expected to be captured or retained.

DESIGN NOTE

B) MESH SELECTION

1. Standard Mesh

STD Mesh, mesh count numbers of which ranges from 2 mesh to 400 mesh, can be used for both Filters and Strainers.

400 mesh can be interpreted as 40 micron @ Nominal.

2. Dutch Twilled Mesh

DTW Mesh can be applied where much finer filtration efficiency is required.

Its efficiency can go up to 2 micron @ Nominal, or 7 micron @ Absolute.

Mesh Filter (Basket) Strainer

Filtration Performance Finer Particle removalCoarse Particles,

generally below 400 mesh, or 50 micron

Code Requirement ASME Sec.VIII Div.1ASME U Stamp Required

ASME B31.3Only the Designing according to ASME code would be enough

Main Material (Body) Plate (or Pipe) Plate, Pipe, Forging & Casting

RFQ Issued by Equipment Dept. Piping Dept.

DESIGN NOTE

C) PRESSURE DROP

Considering the Flow Rate and the Flux Rate, the Size of the Inlet Nozzle will be determined.The Basket will be sized according to the Inlet Nozzle Section Area.

Red circled are the factors that decide the total Pressure Drop of the equipment.Given requirement shown on the very bottom of the calculation sheet is 0.102 kg/cm2and the calculated value of 0.022 kg/cm2 shall satisfy the requirement.

DESIGN NOTE

D) SIZING OF THE BASKET ELEMENT

Even for the same given Surface Area, the Open Area can differ according to the Mesh Count Numbers and the Diameter of Each Mesh Wire.

IPEG’s standard Open Ratio for the Inlet Nozzle Section Area would be 300%, but may vary from 200% to 400% according to the given conditions, requirements or specifications.

II. COALESCERS

To Coalesce can literally mean uniting several tiny droplets of fluid into bigger droptlets, and in the end, separating 2 different coalesced fluids.These 2 different coalesced mass fluids form 2 separate layers of each fluid through the difference in densities of the 2 different fluids.

There are basically 2 major Coalescers that can be mentioned ;One is the Liquid-Liquid Coalescer, which, for example, removes Water from the Diesel Oil (Kerosene),and the other is the Gas-Liquid Coalescer, which removes the liquid from the Gas phase.

Removal Efficiency : Various microns(for Particle Removal Only)

Orientation : Vertical / Horizontal

Flow Direction : Out to In

DRY GAS FILTER

Removal Efficiency : 5 micron (for Liquid & Particle)

Orientation : Vertical / Horizontal

Flow Direction : Out to In

*2 Stage (Coalescing Element + Demister or Vane)

GAS SEPARATOR

Removal Efficiency : 0.3 micron (for Liquid & Particle)

Orientation : Vertical Only

Flow Direction : In to Out (Reverse Flow)

GAS FILTER COALESCER

Application: For inlet water concentration of 2% or below: For higher viscosity fluids

Filtration Rating: 1~70 micron

Outlet Water Content: 10~15 ppm

Liquid-Liquid Separation: Water droplets will notbypass the Teflon CoatedScreen Separator,and will be accumulatedat the bottom of the vessel

LIQUID - VERTICAL

Teflon CoatedScreen Separator

LIQUID – VERTICAL (P)

Application: For inlet water concentration of 2% or below (FiberGlass)For inlet water concentration up to 10% (Poly Flour)

: For higher viscosity fluids

Filtration Rating: Pre-Filter Required

Outlet Water Content: 10~15 ppm

Liquid-Liquid Separation: Water droplets will notbypass the Teflon CoatedScreen Separator,and will be accumulatedat the bottom of the vessel

LIQUID - HORIZONTAL

Application: For inlet water concentration of over 2%: For lower viscosity fluids

Filtration Rating: Pre-Filter Required

Outlet Water Content: 20~50 ppm

Liquid-Liquid Separation: A certain Length of Settling Distance to separate the water dropletsfrom the main process is required(in other words, for Gravity to pull down the water droplets)

** for highly Viscous fluids, horizontal vessel would be much too long to be practical. **

LIQUID – HORIZONTAL (P)

Application: For inlet water concentration of over 2%: For lower viscosity fluids

Filtration Rating: Pre-Filter Required

Outlet Water Content: 15 ppm

Liquid-Liquid Separation: Settling Distance ofapprox. 2~3 times the lengthof the Cartridgesfrom Seat Plate to the Bootis required to separatethe water droplets.(in other words,for Gravity to pull downthe water droplets)

** for highly Viscous fluids, horizontal vessel would be much too long to be practical. **

III. DEPTH MEDIA FILTERSSand, Walnut Shell and Activated Carbon are the typical types of deep-bed-media employed depending on the purpose of their installation. Besides the most commonly used media mentioned above, garnet, ilmenite, alumina, magnetite, anthracite and quartz can be considered for the performance and/or as a media support.

As the media depth filter involves the ability to retain the particles that penetrate throughout the medium channels, rather than on its surface, it requires a certain depth (height) of the media bed. In case the bed is not deep enough and/or the flux rate is high, the particles may pass through the media bed all the way to the downstream, or may dislodge the particles which were previously retained in the channel.

Single Media Depth FilterIn general, the single media filter, represented by “Sand Filter”, employs only one grade of sand as a filtering media. Once it is backwashed, due to the density difference of each sand medium, the bigger and heavier sand medium falls on the bottom, while the finer media remain on top of the media bed. In this case, the filtration performance will be weighted on top 100mm of the media, resulting in more frequent backwash requirement.

Multi Media Depth FilterBesides the support gravel layer, 2 or 3 different types of media can be used in conjuction with one another. Light in weight but larger sized media such as walnut shell or anthracite on the top layer acts as a coarse filtration. Heavier media with smaller size (dense) such as sand or garnet forms a layer under the first top layer, and retains the smaller particles that passed through the top media bed. This allows the entire bed to act as a filter allowing much longer filter run times between backwash and more efficient particulate removal.

III. DEPTH MEDIA FILTERS

Bulk Density : 800 ~ 880 kg/m3Specific Gravity : 1.2 ~ 1.4

Size : 0.5 ~ 3 mm (1~1.5 mm)

Bulk Density : 1,600 kg/m3Specific Gravity : 2.65 ~ 2.75

Size : 0.45 ~ 0.7 mm

Oils are entrapped by the nutshell medium, and adhered

on to the media granules.Also the coarse particles are

retained in the nutshell medium bed.

Various sizes of sand media is graded for various micron

ratings. It is mainly adopted for particle filtration applications in

water treatment.

Walnut Shell Anthracite

Bulk Density : 720 kg/m3Specific Gravity : 1.4Size : 0.8 ~ 1.2 mm

It is employed when efficient removal of bacteria, color, odor

and taste is required.It is well known to have higher

loading capacity than sand.

Sand

TYPICAL TYPES OF MEDIA

Bulk Density : 1,920 ~ 2,420 kg/m3Specific Gravity : 3.4 ~ 4.2

Size : 0.3 ~ 0.5 mm

Finer particles are filtered in the narrow channels within the tightly packed bed of finely

crushed garnet medium.

Garnet

Quartz Sand, Crushed Glasses, Hydroanthracite, Expanded Slate

can be other options for the depth media.

OthersGravel

Bulk Density : 1,600 kg/m3Specific Gravity : >2.65

Size : 3 ~ 5 mm

It is to support the finer layers above and to minimize the loss

of media in such layers, and prevent the strainers from

clogging with the fine media.

TYPICAL TYPES OF MEDIA

Due to high porosity, Coke and Pumice in the water treatment can have a high risk of inhabitation of

bacteria.

1) Normal Operation (Service In)

Each filter is equipped with isolation valves upstream and downstream of each process line, for isolation and for diverting flows during operation and backwashing.

FLOWCHART

2) Isolation for Backwash Preparation(Standby Condition)

This process would be required to ensure all open valves during normal operation are closed, and to prepare to open the necessary valves for the next process.

FLOWCHART

3-1) Gas Scour #1

@4.2 bar

It is to scrub off the particles and/or foreign materials from the media to improve the backwash efficiency in the following backwash cycle.

FLOWCHART

3-2) Gas Scour #2

@4.2 bar

It is to scrub off the particles and/or foreign materials from the media to improve the backwash efficiency in the following backwash cycle.

FLOWCHART

3-3) Gas Scour #3

@4.2 bar

It is to scrub off the particles and/or foreign materials from the media to improve the backwash efficiency in the following backwash cycle.

FLOWCHART

4) Water Backwash

During the reverse flow “Backwash”, the expanded bed releases the trapped particles which is then driven out to the backwash outlet along with the backwash water. Backwashing involves a range of velocities to achieve levels of bed expansion up to at least 30% to preferably 50%.

FLOWCHART

5) Settle

Once the backwash is completed, the bed is allowed to settle and re-stratify before a final rinse and then it is placed back into service.

FLOWCHART

6) Pre-Service

Some oily residue and particles will remain on the bottom part of the vessel after backwash process, as the utilized backwash water is also of a Untreated Water.And this process is to rinse off all remaining foreign materials before the normal operation.

FLOWCHART

One other typical media for applications including, but not limited to the water treatment is the Activated Carbon. Activated Carbon can be the best example of Adsorption. It is often called as Activated Charcoal, Activated Coal or CarboActivatus. They all refer to the form of Carbon which has been processed to have a numerous micro pores that increase the Surface Area available for the Adsorption.

Activated

Carbon

Gases /

Chemicals

Pores

Its high porosity enables 1 gram of Activated Carbon to have a Surface Area of 500m2 or even more.

Activated Carbon Filters are available in :- Pressure Vessel Type and- Canister Type.

ACTIVATED CARBON

ACTIVATED CARBON

A/C Cartridge in

Pressure VesselType

A/C Bed in

Pressure VesselType

A/C Bed in

CanisterType

ACTIVATED CARBON FILTERSPRESSURE VESSEL CANISTER

Element Activated Carbon Activated Carbon

Code Stamp As per Requirement X

Product Class. OEM, Design In-Stock, Ready-Made

Shell MaterialAll Grades of CS, SS,

Alloy, Monel, etc.CS, SS, PE

SpecialRequirement

As per RequirementHIC, Normalizing, S5, etc.

X

Corrosion Allow. As per Requirement X

Shell Usage Reusable Disposable, 1 Time Use

Flow Rate All Rates Low Flow Rate