Horizontal filters for desalination

April 2010

Horizontal filters for desalination

2010

2

Index

• Introduction: Water problem

• Desalination. Water scarcity forecast

• Desalination. Mundial capacities

• Mundial investments desalination forecast

• Simplified diagram of a desalination facility

• Reverse osmosis desalination costs analysis

• Three new technologies to reduce energy requirements

• Filament winding

• Sand filter: External / Internal constructions details

• How does a sand filter work?

• Nozzle plate versus collector arms

• GFRP filters versus carbon-steel filters

3

Introduction: Water problem

• 46 percent of people on earth do not have water piped to their homes.

• In 15 years, 1.8 billion people will live in regions of severe water scarcity.

• One out of eight people lacks access to clean water.

• 3.3 million die from water-related health problems each year.

4

Desalination. Water scarcity forecast

Source: International Water Management Institute

Year 2025

Physical water scarcity

Economic water scarcity

Little or no water scarcity

Not estimated

5

Desalination. Mundial capacities

Source: German Desalination Society (DME)

6

Mundial investments desalination forecast

0

500

1000

1500

2000

2500

3000

3500

4000

Mil

ion

s $

2000 2005 2007 2012

Any

Source: BBC Research, 2008

Year

7

Simplified diagram of a desalination facility

8

Reverse osmosis desalination costs analysis (1/3)

9

Three new technologies to reduce energy requirements

FORWARD OSMOSIS CARBON NANOTUBES BIOMIMETICS

FILAMENT WINDING

APRIL 2010

11

Index

• Introduction: What it is?

• Components of filament winding

• Process

• Properties

• Materials selection

• Advantages and disadvantages to other processes

• Applications

12

Introduction

• Filament winding is a technology to manufacture compound materials

• Quick and precise process.

• Most of the production process is automatic

• The pieces obtained have big mechanical properties and high resistance to

corrosion.

13

Components of filament winding

• Roving creel and tensioners

• Resin bath

• Filament winding machine

14

Process

• It is a process by which continuous resin-impregnated reinforcements are

wound over a rotating mandrel.

• The mandrel can be cylindrical, spherical, or any other shape as long as it does

not have re-entrant curvature.

• The tension on the filaments can be carefully controlled.

• The filaments are applied with high tension in a final product with higher

strength and rigidity.

• The filaments are applied with low tension in a final product with more flexibility.

• The orientation of the filaments can also be carefully controlled.

Hoop winding Helical winding

15

Process

• The angle at which the fiber is laid down will determine the properties of the final product.

• Angles of fiber can be obtained between almost 90º and 25º to the axis

• Closed fiber angles provide great resistance to internal pressure (used in pressure tanks)

• With an angle of 45º provide resistance combined to shear (axes of transmission)

16

Mechanical properties

Strength Strong as high strength steels

Stiffness Greater than most metals (per unit weight)

Lightweight80% lighter than steel

40% lighter than aluminum

Fatigue resistance Extended life

Creep Negligible

Toughness As damage tolerant as metals

Corrosion resistanceFibers inert

Resins chosen depending on the needs

Dimensional stabilityCarbon composites can be designed for near zero coefficient of thermal expansion

Noise and Vibration transmission High damping coefficient

17

Properties of Thermoset Systems

Service TemperatureElongation

at BreakStrength

ºC % MPa

Polyester 60 3 60

Vinylester 80 4-6 80

Epoxy 100 2-10 50-100

Phenolic 120-170 -1,5 20-60

18

Properties of Raw Fiber material

• Glass:

- Cheap

- High strength

- Low stiffness

• Carbon:

- High strength

- High strength

- Lower density than glass

- Expensive

- Up to 3000ºC

• Aramid:

- Good impact resistance- Should only be

pulled - Not compressed

- Expensive

- Solvent at 300ºC

• Other fibres

(Polyethylene, Boron….)

- specific properties

- expensive

19

Material Selection - Fiber choice

• Glass for:

- Low cost

- Transparency

- Corrosion resistance

- High deformations

• Carbon for:

- Strength

- Stiffness

- Creep

- Fatigue strength

• Aramid for:

- Toughness

(pressure vessels)

20

Material Selection - Resin choice

• Polyester for:

- Low cost

- Light translucency

• Phenolic for:

- Fire resistance

- High temperature

• Epoxy for:

- Mechanical propierties

- Toughness

• Vinylester for:

- Corrosion resistance

- High Chemical resistance

21

Filament winding advantages

• Highly repetitive in fiber placement (part to part, layer to layer)

• The use of continuous fibers over whole component area (without joints)

• Depending on the needs can orient the fibers easily

• Avoids capital expense of autoclave

• Structure can be built larger than autoclave size limits

• Mandrel costs can be lower than other tooling costs

• Costs relatively low for materials

• Rapid and precise process.

• No conductivity

• Weight

• Strength

• Corrosion Resistance

• Process Flexibility

• Fibers aligned for load or stiffness

22

Applications

• Oilfield

• Energy storage and Generation

Flywheel, wind energy generation, gas storage…

• Communication Satellite

• Aerospace

• Aviation

• Marine

• Aerodynamic applications

• Chemical industry

• Automotive

• Industrial equipment

• Tanks and silos

• Sports goods

Racquet, bicycle, golf shafts, surf, fishing rods…

23

Sand filter: External construction details

Air relief

Water drain

Manhole

FoundationsManhole

BaseAir backwash

Dirty water

Clean water

Rupture disc

24

Sand filter: Internal constructions details, stresses and applied-loads

Working pressure P1=0,6 MPa

Pressure under the plate P2= P1- ΔP

Differential pressure in filtration PF=0,12 MPa

Differential pressure in backwash PL=0,1 MPa

Pressure exerted by the weight of the sand Pm= 0,02 MPa

PF

PL

P1

P2

ΔPϭ1

ϭ2

ϭ3

Raw water diffuserBody filter

Support nozzle plate for air backwash

Water circulation Air distributor

Air circulation

Diffuser support

Nozzle plate

Union

Pm

Support nozzle plate for filtration

25

Air Backwash

connectionClean water free

of suspended solids

How does a sand filter with a nozzle plate work?

Raw water inlet

Water passes through the diffuser channel

1

2

Water through different size media3

Water through the nozzles

4

5

26

Air Backwash

connection

Inlet

Outlet

How does a sand filter with a nozzle plate work?

Backwash: air application through the air connection for a better expansion and cleaning of the media

27

How does a sand filter with collector arms work?

Clean water free of suspended

solids

Raw water inlet

Water passes through the diffuser channel

1

2

Water through different size media3

Water through the collector arms

4

5

28

Inlet

Outlet

How does a sand filter with collector arms work?

Backwash: water enters and passes through the same stages of the tank in reverse sense from the regular working procedure

29

Advantages of using a strainer nozzle plate collector in relation to the conventional collector arms system:

Possibility of air wash with the consequent saving of clean water.

There are no zones with stagnated water as the clean water is collected from the false bottom.

Optimum washing of the filtration bed with uniform distribution of the water.

Nozzle plate versus collector arms

30

Nozzle plate versus collector arms

Nozzle plate Collector arms

Filter layout

Nozzle plate

Collector arms

Clean water Some dead areas due to a lack of water circulation

31

GFRP filters versus carbon-steel filters

0

1

2

3Temperature

Maintenance

Thermal expansionWeight

Traction resistance

Carbon-steel

GFRP