ampc training final report.pdf

Industrial Training and Graduation Projects Unit

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Chapter 1

1.0 Introduction

In this part I will briefly introduce Al Mirfa Power company. Then I will pass through my

assigned tasks briefly Finally, the content will introduce the

subsequent sections that follow the introduction.

1.1 Al Mirfa Power company

Al Mirfa city located on the western coast of the

Arabian Gulf. It is 170 km away from Abu Dhabi. Al

Mirfa Power company was initially formed in 1993 to

correspond with the instructions of H.H. Sheikh Zayed

Bin Sultan to improve services to the Western regions

people, with an overall cost of 2.6 billion Dh. The Actual production of the plant began in

1995-1996. By the end of 2001, the new desalination station ( Phase B ) was added to

service to increase the water production from 16.2 M.G. per day to 37.7 M.G. per day. The

Company acts in accordance with a license issued on December 6th, 1998 by the regulation

and supervisor bureau that permits it for a period of 25 years from 1 January 1999. The

company produce distill water to the maximum capacity of 37.7 million gallon per day and

generate power to the maximum capacity of 192 MW at Al Mirfa [1]. The organization chart

of the company shown in the figure (1.2). The plant objectives are developing the present

capability for the power plant & distillers, enhancing safety of plant and personnel as well as

protecting the environment, minimizing operational and maintenance costs and training staff

in addition to maintaining higher productivity[1].

Figure 1.1 : AMPC phase A


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1.3 Al Mirfa Power and Distillation Plants

The plant includes four Siemens (64.3 V) gas turbines, each with the capacity of (48 MW).

Electric Power is produced by generators at (11 KV) and is stepped up to (33 KV) for local

distribution, and up to (220 KV) for high voltage transmission system.

Four Waste Heat Recovery Boilers (WHRB) with a capacity of (120 T/h each, in addition to 2

Auxiliary boilers with a capacity of (220 t/h) in phase A and addition 2 Aux. boilers with capacity

of (170 T/h) in phase B are used to produce steam at 230 oC and 16 bar pressure.

Steam pressure is then reduced to 1.8 bar g and 105oC to utilized in three distillers with a

production capacity of 5.4 MIGD each in phase A and another three distillers with production

capacity of 7.5 MIGD each in phase B. Desalinated water is chemically treated on site for healthy

and potable drinking supply according to world health organization standards. Three 10 million

gallons storage tanks are connected to transmission pumping stations[1].

2.0 Tasks

In this part I am going to talk about the tasks assigned to me during my industrial training

program. The first task assigned to me was to join Health, Safety and Environment unit. The

Figure 1.2: The organization chart of AMPC company


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second task was to join the power generation unit. The third task was to join water production

unit and fourth task was to visit remineralization unit. The fifth task was to join the chemical lab

analysis and the final task was visiting corrosion and inspection section in the maintenance unit.

2.1 Health, Safety and Environment department:

Health, safety and environmental unit is a primary section in most large companies and

organizations. This unit aims to minimize any risk could happen by making sure all employees,

workers and labors are working in safe workplaces and in proper and safe conditions. HSE unit

uses risk assessment management protocol to minimize any risks may come with daily work to

acceptable level. Risk assessment is a systematic approach to hazard identification and control. It

should be seen as a process that helps you to identify what elements of an activity can cause

injury to people or machines and to introduce control measures that will reduce the risk of injury

to an acceptable level. In AMPC, risk assessments are carried out by all departments where

significant risks exist under supervision of HSE unit. As a duty of HSE unit to reduce the risk as

possible as it can be, they recommended to change the disinfectant materials from Chlorine to

Hypochlorite due to its negative side on human body in the long run. All pipe lines in the plant

have been colored depending on the fluid flow inside it to help all AMPCs employees to be

aware about the fluid flows inside the pipe and how to apply risk assessments in case of incident

happen. The pipelines colored as following based on the fluid flows in it to make it easy for

everyone to distinguish between the lines. The following table (2.1) shows pipelines colors and

the flowed fluids through it.

Colored pipe lines and storage tanks Used for carrying

Red Fire water used to puts off fire

Green Sea water

Blue Air

Light brawn Oil

Yellow Natural gas fuel

Orange Hydrochloric Acid ( HCl)

Violet Sodium hydroxide ( NaOH )

The unit has a separate building than administration and their system is linked with fire brigade

and emergency of the Al Mirfa city. This department has one firefighting truck and one

Table 2.1 : shows pipelines colors and the fluids flowed in it


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ambulance for emergency cases. HSE unit supervises on daily checking of fire back up system or

safety guards which they are different types of pumps used for pumping water for fire system.

The plant has four different fire extinguishers types, each type used for special type of fire. All

these fire extinguishers checked by HSE unit regularly. Table (2.2) shows the types of fire

extinguishers colors and the purpose of using. As a trainee I spent the assigned period with HSE

unit discussing contractors HSE booklet with safety engineer and be familiar with the possible

risks and the responsibility and actions should be taken. Moreover, I participated in safety

orientation day as a volunteer in how to used fire extinguishers to puts off fire and I attend First

Aid class and I understand the action should I take in case of I fine injured person in accident

area. I have been introduced to different types of alarms such as smoke, heat and fire alarms

used in the plant.

Color Contained material Used for

Black Carbon dioxide (CO2) Puts off electric fire

Red & Blue Powder Puts off wood and paper

Ivory Foam Puts off Diesel, oil, paint, tenner, cleaner, benzene fires

The objectives of HSE are to ensure that all contractors adopt the company HSE requirements, to

protect people, plants and equipment and minimize impacts on the environment. Moreover,

whatever may the pressure for quick completion of the work, proper attention must be at all

times be the prime consideration. In addition, to ensure that all contractors conduct their work

according to the AMPCs HSE policy. It is the responsibility of all contractors, sub-contractors,

employees and agents to comply with all laws and regulations of the UAE and Emirate of Abu

Dhabi under the supervision of HSE department. The individual responsibility of the safety of all

workers in AMPC is required from them. The unit rewarded with ISO 2000. The plant achieve

more than 2.5 million accident free man hours which count for all plant in general and HSR

section in special. [6]

General Description:

The plant can be descript as two separate sections, power generation and water production.

Power generation section exist in Phase A which consists of four Siemens G64.3 gas turbines

and four waste heat recovery boilers operated by the exhaust gas coming from the turbines as

well as two auxiliary boilers feeding the steam to vacuum systems and brine heaters in distillers

Table 2.2: Fire extinguishers colors used in the AMPC


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in case of turbines are shutting down. In addition to the relevant auxiliaries boilers, water

treatment unit, fuel oil supply and storage plant, pressure reduction station of the nature gas fuel

are included.

2.2 Power Generation:

Most of our daily duties cannot be done without electrical power. Therefore, the government

gives high propriety to power generation plant than others. As I mentioned before, ALMPC uses

four Siemens gas turbines linked with four generators to produce electricity. Power generation

unit consist of four gas turbines with total capacity of 192 MW, four waste heat recovery boilers

with total capacity of 480 T/h of steam, four auxiliary boilers two of them in phase A with total

capacity of 440 T/h of steam and the other two in phase B with total capacity of 340 T/h of

steam. The specification of produced steam are superheated steam with temperature of 230 C

and pressure of 16 bar. Two Demineralization units are used in the plant to supply the boilers

with di-ionized water.

Gas turbine:

As previously mentioned, AMPC used gas turbines for power generation. Gas turbine theory

known since 19th

century as Brayton cycle. It is a thermodynamic cycle that describes the

mechanisms of a constant pressure heat engine. For more information, Brayton cycle disgram

shown in the appendix A. The gas turbine unit consists of axial compressor, two combustion

chambers, turbine, gearbox and generator. The gas turbine shaft and the generator shaft are

connected together by gearbox. In startup process, the generator acts as a motor to rotate the gas

turbine shaft. The electrical power needed by the motor is supplied from power network. At this

time the air sucked from atmosphere, filtered from dust to protect the gas turbine and introduced

to compressor through inlet guide vane. Inlet guide vane open partially depending on the needed

load and gradually to control the amount of air needed to entering the compressor. For more

information about startup process I attached startup situation procedure diagram in appendix B.

The compressor consists of 17 stages, stators and rotors. The air enters the first stage of

compressor with pressure of ambient pressure and leaves the last stage of compressor at 13 bar.

The compressed air fed to two combustion chambers. This air used for couple purposes, part of it

passes directly to burners for combustion process, the major part passes through holes in

perforated inner shell and mixes with combustion gases to reduce the temperature from 1200 C

to 800 C and other part cools turbine blades. In the combustion chamber, a small flame


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established by ignition system and the amount of entering air is limited to prevent extinguish the

small flame, then the fuel gas supplied to the chambers by gas fuel system at 3.5 bar and the

main flame establish. Fuel-Air ratio is equal to 19-1 by weight and 10-1 as volume and

controlled by control valves. The fuel could be either natural gas or diesel. Diesel fuel is used as

standby fuel in case of no supply of natural gas. Diesel fuel must be atomized by steam to be

used. The combustion chamber consists of three burners. These burners work in two different

modes of combustion, diffusion and premix. In startup procedure, diffusion mode must be started

until the temperature of the chamber reach a certain value then the operator turns the combustion

mode to the premix to reduce emission of gases. In diffusion mode, air and fuel mixed inside the

combustion chamber and the flame is longer than premix mode flame, also it emits gases which

damage the environment. While the premix mode has shorter flame and the air and fuel mixed

before entering the combustion chamber. Once the combustion chambers enter the service, the

load is reduced on the motor gradually. The flow gases resulting from burning fuel will enter the

turbine stages with temperature of 800 C and rotate the turbine shaft. Turbine section consists of

four stages, stators and rotors. When the rotation speed of the turbine shaft reaches 4150 rpm, the

generator stops acting as a motor. Once the rotation speed of turbine shaft reaches 5430 rpm,

(Gear box reduce the turbine speed from 5430rpm to 3000 rpm) this reduction of turbine speed

by gearbox has two functions: increasing the torque and bringing the rotation speed of the shaft

to accurate speed that required to produce 50 Hz ,that allowed to connect the gas turbine

generator to the electrical grid.

The generator After connecting GT generator to the electrical grid, load increases to 48

as

base load by increasing input energy as fuel gas. The exhaust gases leaving turbine with

temperature of 530 C. These gases either used in the waste heat recovery boiler (combined

cycle) or send to atmosphere(open cycle).[7][8] The following figure (2.1) shows the above

described process.


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Fuel-Air Ratio Calculation:

Supplied natural gas to AMPC consist of 93.6412 mole percent of methane, 4.179 mole

percent of ethane and the residue is other gases. To simplify the calculation I will assume natural

gas fuel is methane gas. The chemical equation of methane combustion (CH4):

the stoichiometric combustion shows that 1 kmol of CH4 meets 2 kmol of O2. Result 1 kmol

CO2 + 2 kmol H2O. That means:

and since the air consists of 21% of

O2, and 1 kmol CH4=16 kg CH4, then we need:

.

Excess air ratio (l)=

(2.1)

Since we use 19 kg air for combustion 1 kg of methane then l=1 and that is mean the required

air for combustion equal to available air.

Figure 2.1: shows gas turbine main components and auxiliary systems


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Gas Reducing Station:

Usually natural gas fuel is highly pressurized as it transfers from place to another through

pipelines. However, once it reaches the plant, it needs to be brought up to the needed

specifications. This often means that solids and liquids have to be filtered out and the pressure

has to be reduced. To achieve that, AMPC install a gas pressure reducing station. The

pressurized natural gas reaches the plant at 40 bar. Gas station treat the arrived natural gas by

removing impurities and reducing the pressure up to 23 bar by increasing pipeline diameter.

Then the fuel gas sent to power generation unit and the pressure reduced again up to 3.5 bar by

pressure control valves. What worth to mention, in the plant fuel gas used in gas turbines and

auxiliary boilers.

Lubrication Oil Systems:

Lubrication oil system provides continuous supply of filtered oil at required temperature and

pressure to lubricate the turbine bearings. The main components of the Lubricating Oil System

are three oil pumps, (generally in normal operation , main oil pumps put in service, and the

others are standby) lubrication oil tank, oil filter, oil cooler, and pressure control valves. The

main purpose of using lube. oil system is to avoid metal to metal contact by making oil film

between the two metals, also removing the generated heat due to rotation. Before gas turbine

shaft rotate, lift oil pump put in service and pumps oil to the bearings. This oil shift the turbine

shaft upward by very small distance to decrease the friction and make the shaft free to rotate.[7]

Lubrication oil system shown in figure (2.2).


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Steam Generators (Boilers) and Di-ionized Water plant (Phase B):

In the plant, two kind of boilers are used to produce steam that required in desalination

process, Waste heat recovery and auxiliary boilers. Main difference between WHRB and Aux.

Boiler is ,that in WHRB the heat source is the waste heat that carried by flue gases at the end of

Gas Turbine process (Combined cycle), while the main heat source in auxiliary boiler is fuel or

diesel firing system. All other process are same for both kinds. Another main difference is that in

WHRB two flue gas stacks are there with separating diverting damper for the utility of using

open cycle or combined cycle as operation requirement.

The supplied water to the boilers must be di-ionized water. The di-ionized water generated in the

AMPC by demineralization plant. A small part of produced distillate water in the desalination

process is sent to the demineralization plant. Where the distillate treated by removing of non-

desirable ions by replacing them with more desirable ions. This process achieved by two ions

exchanger beds, anions exchange bed and cations exchange bed packed with polymeric

materials. When the water passes through the anions exchange bed, the positive ions in the water

replaced with the Hydrogen ions supplied from the resin of anions exchange bed. Then, the water

introduced to cations exchange bed, where the negative ions in water replaced with the

Figure 2.2: shows Lubrication oil system and its components


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Hydroxide ions supplied by the resin of cations exchange bed. The output treated water called di-

ionized water where it conductivity less than or equal to 1 s/cm.

Waste Heat Recovery Boilers (WHRB) Phase A:

As I mentioned previously, there are four waste heat recovery boilers in the plant, all of them

in phase A. These types of boilers derive by exhaust gases coming out of gas turbines. Since

these gases carry high energy due to its high temperature 520 C. The GTs exhaust gases can be

either send to the atmosphere or the WHRB through a Diverter Dumber gate. The capacity of

this boiler 119 T/h of superheated steam at 16.5 bar and 220 C. WHRB consists of three bundles

of tubes economizer, evaporator and super heater tubes in additional to flash drum. The process

starts when di-ionized water pumped to the economizer, this level locate on the top of the boiler

and both exhaust gases and di-ionized water have lowest temperature. The heat transfer to water

due to temperature difference. Then, the water passes to flash drum and heated. After that part of

the water sent to the evaporator which locate in the middle of the boiler. In this level, water boils

and returned back to the flash dram where the flashing process taking place. The saturated steam

leaves flash drum to the super heater tubes. The super heater rises the temperature of the steam

and convert it to superheated steam. The produced superheated steam sent to the Medium

Pressure (MP) Header. The water cycle in this type of boilers is forced circulation. MP header

before it supply the brine heater in the desalination unit, it passes through desuper heater to

reduce the temperature and pressure of the MP steam up to 126 C and 1.8 bar respectively [9].

Auxiliary Boilers Phase B:

Auxiliary Boiler is an apparatus to produce superheated steam. Thermal energy released by

fuel combustion is used to generate steam at the wanted pressure and temperature. The plant has

four auxiliary boilers used in case of gas turbines out of service during law demand on electrical

power and maintenance periods. Two auxiliary boilers exist in phase A and the other two in

phase B. The number of burners and capacity are the differences between the two phases while

they have the same process. The boiler made up of three bundle of tubes economizer, evaporator

and super heater in addition to water drum and flash drum. The process starts when the di-

ionized water introduced to the deaerator. The deaerator remove dissolved gases in water such as

Oxygen from the feed water which is an essential process. The presence of Oxygen in water

considered very dangerous issue lead to corrosion the boiler. Using deaerator, reduce the needed

amount of chemicals by 40% that used to remove mainly the oxygen and other dissolve gases.


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The feed water leaving the deaerator inter the economizer to rise the temperature of the water.

Then the water passed to steam drum where part of this drum filled with water and the other half

filled with saturated vapor . The steam drum is locate on the top of the boiler and it is connected

with the water drum by bundle of tubes. The water drum locate in the bottom of the boiler. The

water move from the steam drum to water drum under natural circle. While the water feed

through a bundle of tubes to water drum, these tubes form the walls of firing combustion room of

the boiler (heat source). Four burners supplied by (natural gas or atomized diesel) in the

combustion room, heat transferred to the water through tubes. The heated water collected in the

top hot drum. The hot water rise up due to its high temperature and it reaches steam drum under

high pressure and temperature. The flashing start in the steam drum and the steam generated. The

collected steam in the steam drum rises to the super heater. The super heater supplies the

saturated steam with the needed heat to convert it to superheated steam. In the outlet of the super

heater there is a pressure control valve used to control the pressure and keep it at 16 bar. The

produced superheated steam leaving the super heater to MP heater[11]. The schematic diagram

of the auxiliary boiler with its mass and heat balance values attached with the appendix C.

2.3 Water Production ( Thermal Technology process ):

Many countries all over the world do not have easy access to fresh water. Moreover, the water

demand increase continually due to economic development and population growth. United Arab

Emirates is one of these countries. Desalination process is offering a solution for these countries

to get a fresh water if they have coastline by getting advantages of using sea water. Desalination

process is a method of removing salt and other minerals from saline water. Salt water is

desalinated in order to produce fresh water that is suitable for human daily consumption,

irrigation, industrial process and other uses. In this process we need sea water and energy as

inputs, and we are getting distillate or fresh water and brine as outputs. Desalination techniques

are classified in two main parts: thermal and membrane technologies. The following figure(2.3)

shows the methods of the thermal and membrane technologies.[2]


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AMPC use Multistage flash (MSF) as desalination technology. This technique accounts for more

than 60% of the global desalination industry [4]. In addition, it is the major source of fresh water

in the Gulf countries as I mentioned previously. In my report I will focus on this method.

Multistage flash process( MSF) is can be describe simply as following; A bulk of hot sea water

passes through several series champers. In these champers the evaporation of hot sea water starts

and the vapor passed the filter from the evaporator side to the condenser side in the distiller. The

vapor will condense and collected. Sea water processes through several cycles to convert it to

potable water. These cycles will be explained separately in the following.

Sea water intake:

Sea water intake aim is to pump sea water to the plant to use for many different purposes such

as produce distillate water, cooling purposes (cooling media for different heat exchangers),and

production of Sodium Hypochlorite solution. The sea water intake system made up of several

equipment. In the beginning of the process, sea water introduced to filtering stages in the inlet of

sea water which is consist of bar and bans screens. Bar screens are used to trap all big size of

marine growth as fish, shells and other pieces like wooden, plastic and metals pieces. While band

screens which is second filtering stage used to remove relatively small substances with size

larger than 1 mm. Controlling flow system of this process depends on the difference in seawater

level between sea water inlet and outlet through the screens by two steps low and high speed.

After sea water passes through the screens, it distributed by seawater downstream to four

channels feed four seawater supply pumps 3 of them in service and one standby mode ( phase A)

where the pumps supply the desalination units in the plant [10].

Desalination Technologies

Thermal Technologies

MultiStage flash (MSF)

Multiple effect (MED)

Vapor compression

(VC)

Others Membrane Technologies

Electrodialysis (ED)

Reverse Osmosis (RO)

Figure 2.3 : thermal and membrane desalination techniques


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2.4 Sodium Hypochlorite plant (Disinfection process):

In the presence of oxygen in the sea water, the bacteria and microorganisms have suitable

environment for excessive growing and breeding. To overcome this problem, AMPC used

sodium Hypochlorite (NaOCl) as a disinfectant agent to kill these living micro-organisms.

Sodium Hypochlorite dosing can be continuous which happen either at sea water intake or at the

distribution channels in front of pumps. The dosing rate around 2000 ppm/m3 at sea water inlet

by a flow indicator and controller. The other way of dosing is shocking or discontinuous. This

way is performed at the intake structure before bar screens. The shock dosing flow rate (3 to 4

times of continuous dosing) and it controlled by flow indicator and controller. Sodium

Hypochlorite solution prepared and send to storage tank, from this tank Sodium Hypochlorite

pumps to the injection points. The production process of Sodium Hypochlorite is performed in

the AMPC plant. The disinfectant agent generated by electrochemical process. I visited Sodium

Hypochlorite plant and I understand how the production process is going on. The following table

(2.3) shows the NaOCl plant technical data.

Subject Value Unit

Number of Hypo. Units 2, 1 in service -

Number Electrolyzer per Unit 4 -

Number Electrolyzer in service per unit 3 of 4 -

Number of cells per Electrolyzer 10 -

Maximum Chlorine production 110 Kg/hr

DC voltage output at maximum Chlorine production 110 Volt

DC current applied at maximum Chlorine production 3500 Ampere

Total S.W. flow to distillers to be disinfect (summer case) 66000 T/hr

Sodium Hypochlorite concentration output 2000 Ppm/m3

Sea water supply to Electrolyzers 55 m3/hr

The Sodium Hypochlorite production process simply can be explain as following, sea water

supplied to the plant from sea water by one branch of sea water main supply header. Seawater

passes through seawater strainer and flow control valve to inter three Electrolyzes. The

Electrolyzer consists of ten cells, each cell made up of anode and cathode submerged in

Table (2.3): Sodium Hypochlorite plant technical data


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seawater. At the same time a DC voltage applied on the terminal of series cells with seawater as

electrolyte solution. The electrolyzed brine solution is being carried out contains the sodium Na+

and Chloride Cl- ions distributed in the solution. Figure (2.4) shows schematic diagram of the

NaOCl production process.

Air Blowers

NaOCl Generators

(Electrolyzers)

Sea Water Booster Pumps

Sea Water inlet

Chemical Dosing Pumps

S.W. FCV

Dosing FCV

Sea Water dilution Line

S.W. intake

injection point

Storage Tanks

T o Phase B

Storage Tank

S.W. intake

Pumps injection

point

H2 gas collectors

Sea Water

NaOCl solution

H

Air

Sodium Hypochlorite system

H 2 Exhaust

+

-

DC power supply

110V Dc/3500amp.

S.W. dilution FCV

The main electrochemical reactions series in passing brine are shown as following with the

discretion. At the chloride generation anode: -----------R1, while at the cathode

side:

-----------R2. Then reaction between Chlorine (R1) and

Hydroxide (R2) ions react to form hypochlorite as shown:

---------R3. By applying mass balance, it can be noticed Sodium hypochlorite production in

the following reaction: -----------R4. The overall reaction of this

process can be represented as following: ----------

R4.[3] The produced NaOCl leaving the Electrolyzers with concentration of 2000 ppm as

maximum concentration. The Sodium Hypochlorite solution and Hydrogen gas leaving the

electrolyzer to the two storage tanks. The produced NaOCl distributed to sea water intake main

Figure 2.4: Schematic diagram of Sodium Hypochlorite production plant


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inlet channels and one branch feed seawater intake pumps. While the Hydrogen gas released to

atmosphere from the Sodium Hypochlorite storage tanks to prevent accumulation and keep it out

of lower explosive limit to prevent any possible explosion due to Hydrogen-Oxygen mixture.

The following calculation shows Sodium Hydrochloride dosing for phase A. The dosing rate of

disinfectant is 2000 ppm/m3 of sea water. The total seawater for phase A distillers:

,

, in the plant they round the previous

value to 40000

,

, so 80

of pure

Sodium Hydrochlorite is needed for phase A. The capacity of Sodium Hypochlorite

Electrolyzers

. This calculation based on full capacity of phase A desalination unit in

summer conditions (seawater temperature 35C). The maximum Sodium Hypochlorite

production can be calculated as following:

= 110

of pure

Sodium Hypochlorite.

2.5 Desalination Units ( general description of the process ):

AMPC used multi-stages flashing (MSF) as a desalination method as I mentioned before. MSF

has advantage on other thermal desalination method by making the hot brine flow freely and

flashing process happen in a series of stages in the evaporator side in the distiller, this feature

keeps the concentrated brine away from the condenser tubes, which prevent the formation of the

scales on the outer surface of the condenser tubes. This layer of scales acts as insulating layer

and decrease the thermal conductivity of the tubes. The plant has two desalination units; phase

(A) and phase B. Both phases have same process but the number of distillers is different. In my

report I will focus on phase (B) since both phases have same process and procedure. Phase (B)

desalination plant consists of three Multi stage Flush distillers with maximum capacity 22.5

MIGD. Generally, the distiller consists of 21 stages, 18 of these stages make up the heat recovery

section with the remaining three being the heat rejection section. The MSF desalination unit

consists of the following sections: Heat Rejection System, Blow Down System, Brine Recycle

System, Vacuum System, Distillate System, Steam and condensate System.


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The distiller includes three major sections: brine heater, heat recovery section, and heat

rejection section. The number of stages in the heat rejection section is less than the heat recovery

section. The brine heater supplies the needed heat to the recycle brine stream to drive the

flashing process until recycle brine stream reaches the top brine temperature. Flashing occurs in

each stage, where an amount of product distillate water is generated and accumulated across the

stages in the two sections. Vapor forms continuously in all stages. As we go from stage one to

the last stage, the temperature of the brine water decreases and the vacuum increases. This

pressure difference between stages allows for brine flow across the stages without any assistance

of pumping power. The flashed vapor after passing the demister filters, condenses on the tubes of

the condenser. The released latent heat by the condensing vapor is used to preheat the brine

recycle stream before it goes to brine heater. In heat rejection section, seawater feed introduced

to the condenser tubes of the last stage with flow of 8300 T/h. Then this stream leaves the heat

rejection section as two parts, first part is rejected back to the sea with flow of 3894 T/h, and the

other part is make up stream which to be sent to deaerator as in the last stage in the heat rejection

section with flow of 4406 T/h. Deaerator stage is packed with O-rings to remove Oxygen and

other non-condensable gases from the stream and send it to evaporator side in the last stage.

Make up line keeps brine concentration factors and brine level in acceptable limits. In the same

time, two streams are pull out from the brine pool in last stage evaporator side, as a brine blow

down and brine recycle stream. The brine blow down is pumped to the sea by brine blow down

pump with mass flow rate of 14300 T/h. The brine recycle stream is sent to the last stage in the

heat recovery section condenser side with flow of 14300 T/h by brine recirculating pump. The

rejection of brine which known as brine blow down is necessary to control the concentration of

salt in the unit and maintain the brine level in all evaporator side of all stages by maintaining last

stage brine level. Since treatment of the seawater intake is limited to simple screening filtration

and disinfection, 15.4 L/h of anti-scalent is injected to the unit in the brine recycle line and 44.1

L/h antifoaming is injected to the makeup line. The brine recycle stream introduced to last stage

in heat recovery section condenser side with temperature of 46.2 C. After the stream passed the

heat recovery section condenser side, it leaves with 103.5 C temperature and sent to the brine

heater to increase it temperature to the top brine temperature 110 C. Then it sent back to the heat

recovery section evaporator side and evaporation process continue. The condensed vapor on the

condenser tubes collected as distillate water in the collector in every stage. The distillate flows


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toward the last stage in the heat rejection section then sucked by distillate pump and sent to the

remineralization unit and demineralization. The total mass flow rate of the produced distillate is

equal to 1407 T/h [10]. The overall mass and heat balance values of the phase B desalination unit

shown in the appendix D. Figure (2.5) shows schematic diagram of the distiller, its main sections

and the flowing streams in the MSF desalination unit. The temperature profile of the distiller

shown in figure (2.6). The numerical properties of the streams entering and leaving the distiller

shown in table (2.4).

Figure 2.5: Schematic diagram of distiller shows the main section in the distiller and the its streams


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Heat Rejection System

Heat rejection section in the distiller consists of three last stages 19, 20, and 21. The main

purpose of using this section is to control the flashing range. Otherwise, the evaporation rate will

Figure 2.6: Profile temperature of multistage flashing desalination.

Table (2.4): shows the measured characteristics of the streams entering and leaving the distiller


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increase which leads to increase the conductivity of the distillate. The temperature of the

supplied sea water feed in the heat rejection section condenser side can be 25 C and above.

Therefore, if the sea water temperature is less than 25 C as in the winter where the temperature

drops to 18 C, sea water temporary pump recirculates the sea water between the inlet and outlet

of the heat rejection section condenser side. The major advantage of the heat rejection section is

the reduced pretreatment applied to the large stream of intake seawater, which requires screening

filtration and disinfection. Therefore, other pretreatment which includes deaeration, and antifoam

additions, is only applied to the feed stream. A 44.1 L/h of antifoam chemicals is injected in the

makeup line before it enters the deaerator. In the heat rejection stages, the feed and cooling

seawater are heated by absorbing the latent heat of the condensing flashed vapor. The following

figure (2.7) illustrates the above describe system.

Heat Recovery System and Brine Heater:

The heat recovery section consists of 18 stages in series. All of them have same duties and

structure flash chamber and a horizontal tube heat exchanger separated by demister filter and

distillate collector. The demister is formed of wire mesh layers. The demister function is to

remove the brine droplets from the flashed vapor. This is necessary to prevent increase in the

salinity of distillate or scale formation on the outer surface of the condenser tubes. The extracted

brine recycle stream from the brine pool of the last stage in the heat rejection section is

Figure 2.7: Heat rejection system with its all sections and streams lines.


21

introduced to the condenser tubes of the last stage in the heat recovery section. As the stream

flows in the condenser tubes across the stages it absorbs the latent heat of condensation of

flashing vapor in each stage therefore the temperature of the brine stream increases as we go

toward first stage in the heat recovery section, it is kind of preheating. The brine stream leaves

the first stage of heat recovery section condenser side with temperature 103.5 C and introduces

to a heat exchanger called brine heater. The brine heater used a low pressure steam with 164.6 C

temperature and pressure of 1.8 bar as a hot media to rise the temperature of the brine several

degrees to reach top brine temperature which equal to 110 C. In case we exceed this

temperature, Sulphate scale formation will start and it considered as hard scale where it is very

difficult to remove. After the brine passes through the brine heater and it has been heated up, it

introduced to the first stage of the heat recovery section evaporator side with TBT of 110 C and

flow of 14300 T/h. A 8.9 T/h of the condensate steam used in the brine heater to heat up the

brine, and returns back to the condensate header. The other part of condensate steam pumps to

power generation plant with flow rate of 155.7 T/h. If conductivity of condensate steam is less or

equal to 5 s/cm it will accepted, otherwise it will be send to culvert. The hot brine start to

evaporate once it introduce to the evaporator side in heat recovery section. The vapor rise and

pass the demister filters to the condenser side and condense on the condenser tubes and collected

as a distillate in the distillate collector. The same process happen in all stage. The purpose of

using demister filter is to prevent water drops from passing the evaporator side to condenser side.

In case of water drops pass the demister filter the conductivity of the distillate will increases due

to the salty water drops. If the conductivity of the produced distillate exceeds 5 s/cm, the

distillate must be rejected. The temperature of the brine decreases continually as the bine passes

through the stages one by one and the lost heat is taken by the vapor. In the same time, the

vacuum start to increase in the stages as we move toward the last stage to keep the evaporation

process in running mode in all stages and in the same time does not exceed the flashing range. In

case of the flashing range exceeds the design range, the amount of produced vapor will be more

and as a result the velocity of the vapor will increase and that leads to carryover of atomized

brine and contaminate the product water. This vacuum is derived by the vacuum system which

will describe later. When I entered the distiller stages, I noticed that the amount of the salts

caught by the demister filters in the first stages is much bigger than in the last stages and the


21

happen due to the high temperature of the hot brine that coming from brine heater directly. The

following figure (2.8) shows the describe process happen in single stage [10].

Vacuum system:

The MSF process operates over a temperature range of 110 to 30 C. This involves the

majority of the flashing stages operate at a temperature below 110 C and under vacuum

pressure. For that reason, all flashing stages are designed to operate under full vacuum condition.

Vacuum system is very important part in MSF desalination and it is working based on Venturi

theory. It participate with the brine temperature in deriving the flashing process in the flashing

stages. The vacuum system consists of three condensers and five ejectors, two of them in service

in normal operating condition. The system takes the needed energy from medium pressure steam

header which coming from boiler with 16 bar pressure and 3.5 T/h mass flow rate. The vacuum

system connected to the distiller stages condenser side to apply the vacuum in the distiller stages.

The working mechanism of the system start with medium pressure steam passes through startup

Figure 2.8: Multistage flashing process in one of the stages.


22

ejector or hogging ejector, this ejector sucked the non-condensable gases and throws it to

atmosphere. Startup ejector stays in the service until the pressure in the first condenser of the

vacuum system reaches 160 mbar. Then the first and second ejectors inter the service and startup

ejector goes out of the duty. After the medium pressure steam passed through the first ejector, the

first condenser takes all non-condensable gases from distiller stages. First ejector sucks non-

condensable gases and vapor from the first condenser and makes the first condenser under

vacuum. The first ejector takes non-condensable gases from first condenser and send it to the

second condenser with steam. The second ejector sucks the non-condensable gases from the

second condenser and sends it to the third condenser with steam. The collected non-condensable

gases in the third condenser are vented to atmosphere and the condensed vapor send to culvert.

The three condensers used a cold sea water stream as a coolant. Figure (2.9) shows the

components of the vacuum system and the direction of the sucked gases [10].

Scaling Phenomena and Tubes Cleaning System:

Plant operation is hugely improved with adding efficient anti-scale (poly maleic acid sodium

salt), anti-foam (poly alkaline glycol ether) and corrosion control chemicals and use of

Figure 2.9: schematic diagram of the vacuum system of phase B distiller

To Remi. B


23

construction materials capable of withstanding the harsh operating conditions. However, scaling

formation phenomena still serious problem usually faced in the distiller. This problem lead to

sequence of problems affect the production and efficiency in general. If we go deep, we will find

that formation of scales in the brine heater and tubes condenser lead to reduction in heat transfer

coefficient value of tubes by forming new layer of scales in inner wall of the condensers tubes,

this called in heat transfer science fouling phenomena. In this case, more steam is needed to

maintain the top brine temperature and as a result gain output ratio (GOR) will reduced. If the

steam flow is not increased, the top temperature will be lowered than the needed, so the gain

output ratio (GOR) is still reducing. Figure (2.10) shows the difference in losses of heat transfer

as a temperature in clean tube and tube affected by scales.

Moreover, as I saw some condensers tubes totally blocked due to scales which reduce the

amount of brine pass through the condenser tubes and that will reduce gain output ratio more and

more. What worth to mention is scaling rate increase with the temperature, so the brine heater

and heat gaining section are more affected by this phenomena than heat rejection section. The

scales form in the evaporator side in the heat gain section but it has not same importance as in

Figure 2.10: shows the effect of scales on heat transfer in the condenser tubes


24

condensers tubes. See the following Figure (2.11), in the upper left side, the Figure (2.11) shows

the blocked tubes in the condenser side due to scale, and the upper right side shows the scale

forming in the wall of the evaporator side in the distiller, while the two down pictures show the

scales caught by demister filters early first stages.

To reduce and control this phenomena and keep it in the designed limitation, the plant injects

anti-scale chemicals which is consider as chemical way of cleaning to the distiller. Also it uses

sponge balls cleaning system as a mechanical way of cleaning for removing soft scales such as

Calcium Carbonate from condensers tubes. The mechanical way operates automatically every

four hours for in a day. It supposes to clean every tube between six to eight times in a single day.

In shutdown condition, HCl acid cleaning is applied to the brine heater tubes, demisters, and

condensers tubes to remove scales. Anti-scales is injected to brine recycle line with flow rate

15.5 L/h in normal summer operating conditions. All antifoam and anti-scales concentrations

calculations will be shown in the laboratory section since the it is responsible about chemical

dosing [10].

Figure 2.11: shows the formed scale in wall side of evaporator and condenser tubes.


25

Sample design calculations of multistage flashing desalination unit:

I prefer to put all needed parameters for calculation in the following table (2.5), for simplification

and clarification.

Description Symbol Phase A Phase B Unit

Top brine temperature TBT 105 110 C

Brine blow down temperature BBDT 40.9 46.2 C

BH inlet temperature BHTin 96.65 103.5 C

Distillate production Gd 1025 1407 t/h

Recycle brine flow rate Gu 9990 14300 t/h

Makeup flow rate Gz 3880 4406 t/h

Condensate production Gc 145.963 155.7 t/h

Steam Enthalpy Hs 656.83*4.18 2848 J

Condense Enthalpy Hc 115.42*4.18 465.5 J

Sea water salinity Ssw 47800 47000 ppm

brine blow down Salinity SA 64995 69100 ppm

Number of stages N 19 21 -

Specific power consumption 4.76*10-3

3.96*10-3

kw.hr/ kg dist.

B.H. condensate temperature 115 116 C

HRS sea water flow rate 14050 8781 T/h

Based on the above parameters of phase A and B, the design calculation of multistage flashing

desalination unit has been done in the following table (2.6). All equation used in table (2.7) is

taken from AMPC desalination manuals.[10]

Table 2.5: Phase A and phase B parameters.


26

Formula Phase A Phase B Unit Eq. #

Recirculation/Production

Ratio (U) Gu/Gd 9.74634146 10.1634684 -

2.2

Feed Ratio (f) Gz/Gd 3.78536585 3.13 - 2.3

B.B.D. Concentration Ratio

(CFa)

f /( f-1 )

1.35901926 1.46948357

2.4

B.H. Concentration Ratio CFa* (U-1)/U 1.21958035 1.32489872 2.5

Flushing Range ( Delta T) TBT-BBDT 64.1 63.8 C 2.6

Effective temperature diffr. TBT-BHTin 8.35 6.5 C 2.7

Flushing brine temp

difference between stages T/n 3.37368421 3.03809524 C

2.8

Gain output ratio Gd /Gc 7.02232758 9.03660886 - 2.9

Performance ratio Phase 1 GOR*(2261/(hs-hc)) 7 - - 2.10

Performance ratio Phase 2 GOR*(2326/(hs-hc)) - 8.9 - 2.11

Total Heat transferred qnet+qej 330974579 389477670 Kj/hr 2.12

Net Heat heat transferred ms*(hs-hc) 330440262 380827950 Kj/hr 2.13

Total specific heat

consumption Qt /Gd*1000 322.902028 276.814264 Kj/Kg

2.14

Net specific heat

consumption Qnet/Gd*1000 322.380744 270.666631 Kj/Kg

2.15

Brine velocity in B.H single

tube Gv/(NBHT*(Din/2)

2**1.038) 1.97 2.05 m/s 2.16

Brine velocity in HGS

single tube

Gv/(N

HGS*(Din/2)2**1.038) 1.97 2.05 m/s

2.17

2.6 Remineralization unit:

This unit has been visited by me and supervising engineer, he gave me a general idea about the

process happing there and we saw how they control the hardness content in the produced potable

water. The Remineralization unit has been design and installed in the plant to treat distillate

water and produce potable water. This process can be achieve by increasing hardness content in

the distillate water. The solubility of the lime is very important in this case and to achieve the

needed solubility Carbon Dioxide is added and dissolved in the in the distillate header to increase

Table (2.6): Sample calculation of phase A and B


27

its solubility, as known solubility of lime hydroxide is 1 to 2 mg/l. Due to acidification reaction

the pH of the distillate will increase and lead to increase the solubility of the distillate water.

Lime powder is used to increase the hardness of the distillate water and potable water produced.

Sodium Hydroxide is added to the treated water to control pH. The following table (2.7)

illustrates the specification and characteristic of the potable water produced by the unit.

Chemicals Concentration

Total hardness, as CaCO3 50 -105 ppm

Total alkalinity, as CaCO3 55-85 ppm

Free CO2 0.8-1.2 ppm

Free Chlorine 0.7-1.0 ppm

pH 8.5-8.8

Calcium as CaCO3 55-85 ppm

The needed CO2 gas is taken from desalination unit phase B second condenser of vacuum system

with water vapor with considerable amount as CO2 inlet point 1 in figure (2.12) . These mixed

gases are sent to separator vessel to separate the gases including CO2 than water vapor. The

separated gases typically contain 60% to 85% of CO2. It compressed to activated carbon filter to

clean it and remove bad smell. Then, the cleaned gases introduce to CO2 absorber from bottom

and the distillate water from the top of the absorber where the concentration of the CO2 in the

distillate takes a place as shown in the figure (2.12). The distillate comes from desalination unit

by distillate header see point 5 in figure (2.12). The two Silo tanks are filled with the needed

amount of lime powder then, the power weighted inside two proportional tanks. After that, the

system will proceed with the automatic sequence for filling the lime dissolution tank. The

dissolution tank guarantee the correct quality of the lime powder to be diluted with distillate

water inside the two lime dissolution tanks. As a result of dilution, the lime milk concentration

will be 5%. At this point, the lime milk solution is sent to the lime saturators by one of three lime

milk pumps. The acidified water and the lime milk will meet each other in the saturators as

shown in figure (2.12), then they will mixed until the total concentration of the solution become

less than saturation condition. Then, the solution is pumped to two lime water buffer tanks to

Table 2.7: shows potable water specification


28

make sure that the operation is going well, secure water quality and control the level of solution

in the saturator by level transmitter. Lime water dosing pumps suck the solution and send it to

the distillate header to face Sodium Hydroxide dosing system. The NaOH is added to the

solution with 5% concentration to regulate the pH up to acceptable limit 8.5-8.8. The added

NaOH and the solution pass through static mixer which provide well mixing conditions and force

the flow to be turbulent to guarantee complete reaction take a place. NaOCl dosing system

injects Sodium Hypocrite to the header as a disinfectant see figure (2.12) point 17. The outcome

of all steps previously mentioned called potable water. The produced potable water send to

storage tanks to be distributed on the consumers. The series chemical reactions take place in this

unit are start with water react with carbon dioxide to produce the carbonic acid, after that it will

react with calcium hydroxide to produce the calcium bicarbonate. The following figure (2.12)

represents Remineralization unit and its process [11]. The chemical reactions equations are

listed in the following. then ( ) ( ) .

lime

saturator

CO2 INLET

s.w.

s.w

Raw TO STORAGE TANK

Na OH dosing

Sludge to dipsal

4

5

1517

16

12

111

3

2

8

9

10

Lime water

dosing

Lime waterbuffer tanks

Sludge pumps

lime saturator

Lime dissolution

tanks

Lime solutiontransport pumps

6

7

14

proportional tanks

NaOCl dosing

Silo tanks

Figure 2.12: schematic diagram of Remineralization unit.


29

2.7 Laboratory department (Chemical analyses ):

Laboratory has very important duties to take care of in AMPC. These duties represented in

monitoring chemical dosing in desalination unit, quality of oils used for lubrications, potable

water content and others duties. Also it is responsible about preservation of the standby units by

checking the chemicals concentrations in the fluid chemicals inside the units which used to

prevent corrosion and scaling in the units. I joined laboratory department for seven days and I

did by myself several tests viscosity test and Calcium hardness. Daily working mechanism has

been explained to me by responsible chemists. The laboratory takes care of routine tests. There

are two types of tests applied in the lab. Fluid test is more common and widely used in lab, the

other test is solid test, where it usually applied on contaminated soil samples. Laboratory takes

samples for testing chemical content from distillers, boilers, gas turbines, generators,

remineralization unit, demineralization unit and others. Lab. routine test can be classified

depending in the period. There are different test categories; every shift tests, daily tests, weekly

tests and monthly test. The samples are taking from different points called sample points. For the

distiller, the lab. running different tests for all liquid streams entering and leaving the distiller.

These tests include pH and conductivity in every shift, cupper and iron weekly, and the turbidity

in every shift specially for recycle brine stream. The chemist makes sure that all test results in

the allowable range. For the boilers, pH and conductivity tests are common for all streams

entering and leaving the boilers. In additional to measuring the pH and conductivity for boiler

feed water, Ammonia and Hydrazine concentrations are measured every shift, while Cupper and

Iron concentrations measured weekly. For the boiler water drum in additional to measuring the

pH and conductivity, hydrazine, phosphate, chloride concentrations are measured twice in a

week. For gas turbines, the pH and conductivity of water used to cool down the gas turbine

blades air cooling system and Generator air cooling system are measured every day. The

lubrication oil in gas turbines is tested and appearance viscosity, flash point, water contain,

specific gravity, total acid number are measured in every month or working hours. Testing anti-

scale concentration and dosing in distillers is very important due to control scaling phenomena.

This due is carried by the laboratory department. Anti-scale dosing depends on the TBT and

makeup flow rate in addition to using tubes cleaning system. Table (2.8) shows the concentration

of anti-scale versus TBT with or without balls cleaning system in normal operation mode.


31

TBT range in C

With tubes cleaning system

Without tubes cleaning system

Anti-scale dosing conc. Anti-scale dosing conc.

< 80 0.8 ppm 1.5 ppm

90TBT95 1 ppm 1.6 ppm

95TBT100 1.3 ppm 1.8 ppm

100TBT105 1.4 ppm 2.1 ppm

The following is sample calculations of anti-scale and antifoam dosing at TBT 101 C with tubes

cleaning system. For anti-scale, TBT = 101C, anti-scale dosing preparation = 0.135 , makeup

flow = 3900 m3/h. Anti-scale flow rate to the distiller is needed to be calculated.

(

) (

)

(

)

2.18

(

) (

) (

)

(

)

, (

)

The lab. checks the amount of anti-scale in the brine water of the distiller continuously by taking

samples of brine and test it by measuring the loss of total Alkalinity (LTA). By calculating

(LTA), the anti-scale dosing can be regulated due to the value of (LTA). Sample calculation of

(LTA):

( )

, 2.20

by getting the values of the of ALK blow down, makeup chloride, ALK of sea water and blow

down, then (

) , this value means the amount of anti-scale is

more than the lower limit. Sample calculation of antifoam dosing based on TBT = 101C,

antifoam dosing preparation = 0.01 (

), makeup flow = 3900 m3/h. Antifoam dosing

concentration with tubes cleaning system regarding the manual = 0.128 ppm. Antifoam flow rate

to the distiller is needed to be calculated:

(

) (

) (

)

(

)

2.21

Table 2.8:Concentrations of injected anti-scale versus TBT


31

(

) (

) (

)

(

)

, (

)

Also the lab. responsible about calculating the concentration of acid used in acid cleaning in the

distiller in shutdown mode. This issue is very critical, since the acid is very corrosive material

and it damage the distiller. The following calculation shows a sample calculation of acid dilution

preparation for acid cleaning. The needed acid concentration can be calculated by calculating the

strength (concentration mg/L) of acid,

N x V = N x V, where N is normality in (N) and V is volume in (mL), N is the new unknown

normality. Strength = N x equivalent weight, where equivalent weight for any acid is equal to:

2.22

And equivalent weight for any salt is equal to:

, 2.23

and the percent equal to: % =

2.24

then N x V = N x V, by plugging the known value:

N x 1 mL = 0.1 N x 11.5 mL N = 1.15 N ,

, this value represents the

acid percent in the acid cleaning solution. The potable water produced in remineralization plant

is tested frequently since it produced for human consumption. Table (2.9) shows the applied tests

on potable water samples and the allowed range in additional to the measure value.

Test pH Conductivity

s/cm

Ca-hardness ppm

Total-hardness ppm

Residue Cl2 ppm

TDS ppm

Allowed range

7 9.2 160 1600 0 200 0 300 0.2 0.5 0.2-0.5

measure value

8.54 140 53 53 77 0.4

These tests applied three times a day. Also the lab. responsible about following the

concentrations of Iron, Cupper, Sodium and Lead by using spectrophotometer [5].

Table (2.9): shows the measured properties in potable water sample.


32

2.4 Corrosion and Inspection section:

The plant has a corrosion and inspection section, it responsible about corrosion control and

inspect the equipment and machines in the plant in additional to welding. Corrosion is the natural

deterioration of a metal in which metallic atoms leave the metal in the presence of humidity

(water) or gases. Generally, corrosion cannot be stopped but it can be minimized by the use of

corrosion resistant materials and the addition of protective coatings. The nature and degree of

corrosion depend on the environment and the metal. In the following, I will specify the most

common types of corrosion are taking place in the plant. Galvanic corrosion occurs When two

dissimilar metals are in direct contact in a conducting liquid, experience shows that one of the

two may corrode. This is called galvanic corrosion. The other metal will not corrode; it may even

be protected in this way. Galvanic corrosion may be reduced by the suitable design and selection

of materials regarding unlike metals and the use of sacrificial anodes. Localized corrosion can be

especially damaging happen in the presence of destructive forces such as stress, fatigue, and

other forms of chemical attack. Stress corrosion cracking occurs at grain boundaries under tensile

stress. It propagates as stress opens cracks that are subject to corrosion, ultimately weakening the

metal until failure. There are effective means of reducing stress corrosion cracking such as

proper design, reducing stress, removing corrosive agents and avoiding areas of chloride and

hydroxide ion concentration [12]. Uniform corrosion develops as pits of very small diameter, in

the order of a micrometer, and results in a uniform and continuous decrease in thickness over the

entire surface area of the metal. Pitting corrosion is a localized form of corrosion by which

cavities or (holes) are produced in the material. Pitting is considered to be more dangerous than

uniform corrosion damage because it is more difficult to detect, predict and design against.

Corrosion products often cover the pits. A small, narrow pit with minimal overall metal loss can

lead to the failure of an entire engineering system. The section also responsible about material

inspection, it applies nondestructive testing (NDT). Generally, NDT is used to assess the

integrity of a system without compromising its performance. NDE uses sensors to get

information about these objects and perform modeling, analysis, and conversion of the

information into materials and defect parameters for performance and in-service life prediction.

The inspection of in-service systems can also be complicated by the fact that these systems often

operate at relatively high temperature in a closed mode [13]. Visual inspection is widely used

nondestructive testing methods in AMPC. This type can observe poor welding, surface defects


33

and corrosion pits. To slow down the corrosion rate as possible, there are several corrosion

protection methods we have been introduced to. The common method used in AMPC is cathodic

protection. This method depends on controlling the charge on the metal surface, and this can be

monitored by measuring the potential of the metal. There are two types of cathodic protection,

impressed current and sacrifice anode. During training period, a corrosion phenomenon appears

on diesel fuel storage tanks numbers three and four. I visited tank number three several times

with supervising Engineer and I discussed the possible reasons behind this case. I toke this case

and analyzed it and I attached my result in appendix E.


34

Chapter Three

Proposal For A Graduation Project

Proposal :

As per my training in AMPC, corrosion issue is a big challenge in industrial fields, as per this

fact along with my analysis of corrosion problem in storage tank. This problem spread overall

the world. Iron is a main metal that is used in construction of many applications as tanks, buried

pipes, machines construction, sheets piles etc This iron under heavy corrosion attack unless it

is protected well. My proposal to use new technology of new materials those used as coating of

metal or used an alternative material instead of steal such as glass reinforced plastic (GRP) when

its applicable. AMPC used four steal diesel storage tanks, the bottoms of two storage tanks were

corroded significantly. The tanks are protected by coating and impressed current cathodic

protection from internal and external sides. Although with all this precautions, corrosion

phenomena still there. This problem not limited on diesel tanks only but potable water also.

Figure 3.1 shows ultrasonic scanning result of diesel storage tank 3 corroded bottom in AMPC.

Figure 3.1 shows corrosion distribution over bottom plates.


35

Chapter 4

Conclusion and Recommendation

To sum up, the industrial training course was very important chance to see the working

environment and involved in it. In addition, the training built on my previous theoretical

knowledge and I see how the pure theories can be applied in the industrial fields. I earned work

field skills and experience during my industrial training course. Also the individual and team

responsibilities were there. I have been in different sections, it provided me an experience in

process and operation control in additional to dealing with troubleshooting by engineering sense.

I contributed in finding the possible reasons behind diesel storage tank failure due to corrosion. I

was lucky to train in AMPC since it has desalination units which directly related to chemical

engineering science such as heat mass transfer. To improve the training course I recommend to

increase the training period up to six months, this will help students in covering tasks in deep.

Also, I recommend to let the trainees attend the weekly meeting in their host companies, this will

help them in sharing their opinions and learning how the meetings are running. It will be great if

trainees host companies provide the trainees with office and supervising engineer keep their

work under observation.


36

References

1- http://www.ampc.ae/en/profile/company.htm, accessed in 21-10-2013 2- http://www.irena.org/DocumentDownloads/Publications/IRENA-

ETSAP%20Tech%20Brief%20I12%20Water-Desalination.pdf accessed in 19-11-2013.

3- http://www.jcsp.org.pk/ArticleUpload/2277-10123-1-RV.pdf accessed in 24-11-2013.

4- http://en.wikipedia.org/wiki/Multi-stage_flash_distillation accessed in 29-11-2013.

5- Laboratory section, Albaseer, Omar. Chemist. Personal interview. 1 Nov. 2013.

6- Health, safety and environmental section, Saad. Safety Eng. Personal interview. 18 Sept.

2013

7- AMPC, Operation unit, Gas turbine, Plant course WED Mirfa C 331, Volume 2,3 and 4.

8- Operation unit, Alhosiny, Mohammed. Gas turbine Eng. Personal interview. 12 Dec.

2013.

9- Operation unit, Raaj. Boiler Eng. Personal interview. 4 Dec. 2013.

10- AMPC training manual desalination units phase B, G187 VD TRN DIS 001, 13 Oct

2013.

11- Maintenance unit, Nayef, Osama. Distiller Eng. Personal interview. 10 Oct. 2013 to 30

Nov. 2013.

12- http://nuclearpowertraining.tpub.com/h1017v1/css/h1017v1_88.htm accessed in 25-12-

2013.

13- http://corrosion-doctors.org/Inspection/NDE.htm accessed in 26-12-2013.

ampc training final report.pdf

Documents

production capacity

power generation unit

water production unit

power plant distillers

maintenance unit

maximum capacity

environment unit

graduation projects