LIM GUOWEI UK20669 YONG HIONG SIENG UK20711 KHAIRUN NAIM BIN TAHIR UK20569 ZAKWAN BIN DERAMAN UK20936

FRESHWATER GENERATOR

Department of Maritime Technology, Faculty of Maritime Studies and Marine Science, Universiti Malaysia Terengganu.

Presentation Outline

i. Introduction

ii. Operation

iii. Types

iv. Construction

Freshwater Generator

By

YONG HIONG SIENG

INTRODUCTION

Function

? Why we need distilled water

?

Naming Variation

? TDS

?

In Practice

?

Functions

To produce high-purity distilled water from seawater.

To produce distilled water from raw freshwater supplies of insufficient or doubtful purity.

Water for boiler;

Portable water for drinking, cooking, dishwashing, ablutionary, hospital and laundry.

Why we need distilled water ?

Naming Variation

Distilling plant; evaporator; distiller; distillation system; desalinator

Seawater Distillate

Total dissolved solids (TDS) = 32000 mg/litre

TDS less than 500 mg/litre

T D S to know

Portable water for crew requirements contains less than 500 mg/litre of suspended solids.

Good quality boiler feed will contain less than 2.5 mg/litre.

Thus, the portable water taken from port is not suitable for use in water tube boilers.

In Practice

It is a statutory requirement that ocean-going (foreign) ships should carry distillation plant for emergency use even if sufficient portable water for normal requirement is carried.

So, people take only a minimum supply of portable water and make-up the rest by distillation of sea water.

A freshwater generator should be capable of operating for a period of at least 90 days at rated capacity without shutdown for cleaning.

By

KHAIRUN NAIM BIN TAHIR

FRESHWATER GENERATOR OPERATION The concept of a freshwater generator is very simple Sea water is evaporated using a heat source, separating pure water from

salt, sediment and other elements

Freshwater generators often use the diesel engine jacket as a heat source, although steam can also be used as a heat source. Because

freshwater generators often use existing heat to run, the cost of operation

is low.

There are two main elements in a freshwater generator: o One, heat exchanger evaporates the sea water, and another

condenses the fresh water vapor into drinking water.

o In the condenser element, the vapor is condensed through cooling,

often simply using cold seawater to cool the outside of the unit.

o The freshwater generator should include a feature to monitor the

salinity of the processed water.

o If the salinity exceeds a specified level, usually between one and ten

parts per million (ppm), the freshwater generator will automatically

return the water to the feed line and put it through the cycle again.

Operating principle o The feed water to be distilled is taken from the flow of seawater

coolant from the condenser outlet (1).

o It enters the evaporator (10) where it evaporates at approximately 40 to 60C as it passes between plates that are heated by the heating medium.

o The evaporating temperature corresponds to a vacuum of 8595%, maintained by the brine air ejector (not shown).

o The vapours generated pass through a demister, where any drops of seawater entrained are removed and fall due to gravity to the brine sump in the bottom of the generator chamber.

o The clean freshwater vapours continue to the condenser (9), where they condense into freshwater as they pass between the cold plates cooled by the cooling water.

1) Seawater feed 2) Heating medium in 3) Heating out 4) Seawater cooling in 5) Seawater cooling out 6) Freshwater out 7) Evaporated steam 8) Demister 9) Condenser 10) Evaporator 11) Brine out

By

ZAKWAN BIN DERAMAN

TYPES OF FRESHWATER GENERATORS

Plate Type Freshwater Generator

Tubular Type Freshwater Generator

Reverse Osmosis Freshwater Generator

PRO & CONTRA

Plate Type Freshwater Generator

Advantage/s

Flexible installation

Easy maintenance

Compatible with variety of heating sources

Disadvantage/s

High cost for Titanium(Plate)

Tubular Type Freshwater Generator

Advantage/s

No fuel consumption

Compact structure

Can be used as cooler

Disadvantage/s

Lower power consumption when overhearted

Reverse Osmosis Freshwater Generator

Advantage/s

Flexible design

Wide range production

Regular chemical dosing

Disadvantage/s

Maintenance high

By

LIM GUOWEI

Main parts of fresh water generator

1. Evaporator

Main function of evaporator is to raise the sea water temperature by steam or hot water passing outside the tubes.

When sufficient heat is provided, it will boil and resulting in vapor rising.

2. Demister

All the vapor entering the distilling section has to pass through demister

The demister will letting vapour to pass through freely but any water particles will impinge onto the wire mesh.

3. Condenser

Condenser takes sea water as cooling water supply and condensate the hot vapor into water droplet and drop on water catchments tray.

4. Salinity Detector

Salinometer measures the density of the distillate.

With an acceptable reading the distillate pump discharges it through a flow controller and a non-return valve to the storage tank.

If the density is unacceptable, the salinometer provides a signal which stops the pump this pass over the double loop to re-enter the evaporator feed line for re-distillation or pass to bilge.

5. Brine Ejector

Water supply is introduced into a nozzle

The pressure drops at the narrow part of the nozzle inducing a vacuum relative to the atmosphere.

The vacuum part will pull brine solution and eject it overboard.

Water supply is introduced into a nozzle

The pressure drops at the narrow part of the nozzle inducing a vacuum relative to the atmosphere.

The vacuum part will pull brine solution and eject it overboard.

Thank You

Question & Answer