effect of fouling factor

ISSN 2249-6343

International Journal of Computer Technology and Electronics Engineering (IJCTEE)

Volume 2, Issue 3, June 2012

33

Optimization In Thermal Design Of Surface

Condenser By Changing Fouling Factor

Vijay K. Mehta,

Abstract: One of the most common operational challenges

encountered with heat exchangers is fouling. Fouling is the

build-up of sediments and debris on the surface area of a

heat exchanger that inhibits heat transfer. Fouling will

reduce heat transfer, impede fluid flow, and increase the

pressure drop across the heat exchanger. As with many

operational concerns, proper planning at the design stage

can minimize the effects of fouling down the road. Designers

use fouling factors to maximize the lifespan, runtime and

efficiency of a heat exchanger by accounting for the amount

of fouling an exchange will sustain over a period of time.

This often results in increasing the surface area of a heat

exchanger, so that fouling will not have as much of an

effect.. This means that the heat exchanger must be able to

function efficiently for long periods of time. Compensating

for fouling by enlarging surface area allows heat exchangers

to function with years of fouling.

Owing to the wide utilization of heat exchangers in

industrial processes, their cost minimization is an important

target for both designers and users.[1]

Keywords: Tube Materials, Fouling factor, Heat transfer

rate, Aspen plus condenser design software, Effect of

fouling factor & Heat transfer rate on surface Area.

1. INTRODUCTION:

Condenser is a type of heat exchanger in which hot fluid

becomes cold fluid. surface condenser is a commonly

used term for a water-cooled shell and tube heat

exchanger installed on the exhaust steam from a steam

turbine in thermal power stations. These

condensers are heat exchangers which convert steam

from its gaseous to its liquid state at a pressure

below atmospheric pressure where cooling water is in

short Supply; an air-cooled condenser is often used. An

air-cooled condenser is however significantly more

expensive and cannot achieve as low a steam turbine

exhaust pressure as a water-cooled surface condenser.

One of the most common operational challenges

encountered with heat exchangers is fouling. Fouling is

the build-up of sediments and debris on the surface area

of a heat exchanger that inhibits heat transfer. Fouling

will reduce heat transfer, impede fluid flow, and increase

the pressure drop across the heat exchanger [2]

Fouling depends on the type of heat exchanger, and the

kind of fluids being transferred. Due to different designs,

composition, and transfer fluid, each type of heat

exchanger will suffer fouling in unique ways. The tube

side of a shell and tube heat exchanger is usually easy to

clean but the shell side can be more difficult to access.

Plate heat exchangers can be taken apart for cleaning on

both sides. Some heat exchangers can be cleaned every

night when the equipment is not in use, while others can

only be cleaned every few months or years. In order to

reduce the amount of fouling in a heat exchanger,

equipment should be cleaned as often as possible. If a

plate heat exchanger were to suffer from the effects of

fouling, extra plates can be added to re-gain performance

if the space permits in the frame.

2. TYPES OF FOULING

There are several types of fouling, each forming

depending on the type of fluid and conditions. The

following are some of the more common fouling

mechanisms;

2.1 Crystallization

Crystallization is one of the most common types of

fouling. Certain salts commonly present in natural waters

have a lower solubility in warm water than cold.

Therefore, when cooling water is heated during the

cooling process (particularly at the tube wall) these

dissolved salts will crystallize on the surface in the form

of scale. [Common Solution: reducing the temperature of

the heat transfer surface often softens the deposits]

2.2 Sedimentation

Sedimentation, the depositing of dirt, sand, rust, and

other small matter is also common when fresh water is

used. This can be controlled to a degree by the heat

exchanger design. [Common Solution: velocity control]

2.3 Biological

Biological Organic growth material occurs from chemical

reactions, and can cause considerable damage when built

up. [Common Solution: material selection]

http://en.wikipedia.org/wiki/Shell_and_tube_heat_exchanger

http://en.wikipedia.org/wiki/Shell_and_tube_heat_exchanger

http://en.wikipedia.org/wiki/Steam

http://en.wikipedia.org/wiki/Steam_turbine

http://en.wikipedia.org/wiki/Steam_turbine

http://en.wikipedia.org/wiki/Thermal_power_station

http://en.wikipedia.org/wiki/Condenser_(heat_transfer)

http://en.wikipedia.org/wiki/Heat_exchangers

ISSN 2249-6343



34

2.4 Chemical Reaction

Chemical Reaction Coking appears where hydrocarbon

deposits in a high temperature application. [Common

Solution: reducing the temperature between the fluid and

the heat transfer surface]

2.5 Corrosion

Corrosion can destroy surface areas of the heat

exchangers, creating costly damage. Fouling will slow

down heat transfer and damage equipment unless it is

dealt with accordingly. [Common Solution: material

selection]

2.6 Freezing Fouling

Freezing Fouling results from overcooling at the heat

transfer surface causing solidification of some of the fluid

stream components. [Common Solution: reducing the

temperature gradient between the fluid and the heat

transfer surface.[3]

3. FOULING FACTOR

The most common way to account for the effects of

fouling in a tubular heat exchanger is the application of a

fouling factor. The fouling factor is a predetermined

number that represents the amount of fouling a particular

heat exchanger transferring a particular fluid will sustain.

In the heat transfer equation the fouling factor is added to

the other thermal resistances to calculate the Total

Thermal Resistance which is the reciprocal of U clean

(Overall Heat transfer coefficient). There is no direct

calculation to determine the appropriate fouling factor to

use for a given fluid in a particular application; however

guidelines do exist to help determine an appropriate

fouling factor. The most common compilation of fouling

factors, to be used for a variety of fluid in various

applications, is supplied by Tubular Exchanger

Manufacturers Association (TEMA). The below table is a

list of general fouling factors used for shell and tube heat

exchangers and common fluids and applications [3]

Table-1 Typical Fouling Factor value for different

condition OF water [4]

Table-2 Typical Fouling Factor value for different

fluids [4]

ConditionsCooling

Water < 50°C

Cooling

Water <50°C

Cooling

Water >50°C

Cooling

Water

>50°C

Cooling Water

velocityv < 1 m/s v > 1 m/s v < 1 m/s

v > 1 m/s

Sea 0.00009 0.00009 0.00018 0.00018

Brackish 0.00035 0.00018 0.00053 0.00035

Cooling tower

with inhibitor0.00018 0.00018 0.00035 0.00035

Cooling tower

without

inhibitor

0.00053 0.00053 0.00088 0.0007

City grid 0.00018 0.00018 0.00035 0.00035

River

mimimum0.00018 0.00018 0.00035 0.00035

River average 0.00053 0.00035 0.0007 0.00035

Engine jacket 0.00018 0.00018 0.00018 0.00018

Demineralized

or distilled0.00009 0.00009 0.00009 0.00009

Treated Boiler

Feedwater0.00018 0.00009 0.00018 0.00018

Boiler

blowdown0.00035 0.00035 0.00035 0.00035

Type of Water

Typical Fouling Factors [m2K/W]

Group Fluid

Fouling Factor

Rf (m2K/W)

Gasoil 0.00009

Tansformer 0.00018

Lubrication 0.00018

Heat Transfer oil 0.00018

Hydraulic 0.00018

Quenching Oil 0.0007

Fuel Oil 0.0009

Hydrogen 0.00176

Engine exhaust 0.00176

Steam 0.00009

Steam with oiltraces 0.00018

Cooling fluid vapours with

oil traces 0.00035

Organic solvent vapours 0.00018

Compressed air 0.00035

Natural gas 0.00018

Stable top products 0.00018

Cooling Fluid 0.00018

Organic heat transfer fluids 0.00018

Salts 0.00009

LPG, LNG 0.00018

MEA and DEA (Amines) solutions 0.00035

DEG and TEG (Glycols) solutions 0.00035

Stable side products 0.00018

Stable bottom products 0.00018

Caustics 0.00035

Vegetable Oils 0.00053

Refrigerating Liquid 0.0002

Several Fluids

Liquid

Gas &

Vapour

Oil

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35

4. DESIGN OF SURFACE CONDENSER:

There are two design of heat exchanger

4.1 Thermal Design:

It’s a primary design of any heat exchanger in which u

optimise by changing flow rate, material etc. Also you

optimise in process by design of two or three pass system

on different loading in different season like as in winter

less cooling load required as compare to summer. This is

based on HEI codes.

Turbine Condensers are designed as per HEI-standards

for steam condensers (HEI means Heat Exchange

Institute) Since 1933 - HEI is a non profit trade

association committed to the technical advancement,

promotion, understanding and education of industrial

heat exchanger, vacuum system etc. HEI has developed

and published Standard

4.2 Mechanical Design:

Design & Construction Code:

Mechanical design based on these codes.

• ASME

• Sec VIII Div I, II, III

• Sec III

• Sec I

• TEMA

• IBR

• IS 2825

5. MATERIAL FOR CONSTRUCTION:

• CS (Plain CS & Micro Alloy Steels)

• LAS

• C-Mn, C-Mo, Cr.-Mo, Cr.-Mo. Ni. - Cr. - Mo,

Ni- Steel

• Stainless Steel.

• Austenitic, Ferritic, Martensitic, Duplex, Super

Duplex

• NF Metals & Alloys

• Al, Cu, Brass, Bronze, Monel, Cupronickel,

Titanium

6. SOFTWARE USED FOR CONDENSER DESIGN:

Condenser Design on Aspen-Plus Software

Compress Software

PVElite

LMTD Calculator.

Condenser Design (Cnd)

Double Pipe Heat Exchanger Design(DHex)

Casketed plate Exchanger Design (PH 2.0.1).

7. RESULTS OBTAINED FROM ASPEN PLUS SOFTWARE

Data taken from Sikalbaha 225 MW ± 10% Combined

Cycle (Dual Fuel) Power Plant Project – Bangladesh

Given Data[5]

Ambient Pressure 1.0130 bar

Ambient Temperature 35.0 ºC

Relative Humidity 98.0%

Design Conditions at different Gas Turbine Load

Steam inlet (kg/s)

Cooling Water Inlet & Condensate Outlet Temperature

(0C)

TABLE 3. Result table produced by Aspen plus

software based on given data of thermal design of

surface condenser [6]

Heat

Trasfer

Rate

(W/m2K)

596.1

Tube Materal (SS 304)

Shell & another part material

(Carbon Steel)

D

E

S

I

G

N

P

A

R

A

M

E

T

E

R

63Reading-1 When Rf=0

Surface Area=430.95m2

0.115Reading-1 When Rf=0.0001

Surface Area=549.30

Steam Inlet/Outlet

(0C)

Density of liquid

(kg/m3)993

Reading-1 When Rf=0.0005




Water Inlet

(0C)





Density of

vapor

(kg/m3)



Water Flow Rate

(kg/s)

663.9

Code Requirement

ASME Code Sec VIII Div 1

TEMA Class

Same Design Parameter for 1 to 8

Readings. Only Fouling Factor change

as per Different condition of cooling

water

Water Outlet

(0C)

1269

995.6

858.4

850.3

773.6

722

670.8



Reading-1 When Rf=0.0008


SteamFlow

(kg/s)

Pressure

(bar)

ISSN 2249-6343



36

8. OVERALL SUMMARY OF RESULT IN ALL

CASES:

Table-4.0 Effect of Fouling Factor on

Surface Area.

Table-5.0 Effect of Heat Transfer Rate

On Surface Area

Fig.-1. Surface Area V/S Fouling Factor

Heat

Transfer Rate

(W/m²K)

Surface

Area(m²)

1269 430.95

995.6 549.3

858.4 637.09

850.3 622.3

773.6 706.93

722 757.46

670.8 815.27

663.9 823.74

596.1 917.44

Fig.-2.Surface Area V/S Heat Transfer Rate

Fouling

Factor

(m² K/W)

Surface

Area (m²)

0 430.95

0.0001 549.3

0.0002 637.09

0.0003 622.3

0.0004 706.93

0.0005 757.46

0.0006 815.27

0.0007 823.74

0.0008 917.44

0.0009 968.9

ISSN 2249-6343



37

9. CONCLUSION:

Heat transfer (Q) is directly proportional to heat

transfer rate (U) and Area. If the value of fouling

factor increases then heat transfer rate decreases.

So, more Surface area required to transfer the heat. So, when we select that type of material which has

less effect of fouling then we reduce the surface

area. Also select the cooling media which has low

value of fouling factor at that time also reduced the

surface area for heat transfer [11]

ACKNOWLEDGEMENT:

I would like to express my deep sense of gratitude

and respect towards my faculty members of Dept.

of Mechanical, Sri satya Sai Institute of Science &

Technology,Sehore,for his valuable guidance right

from selection of the topic. His constant

encouragement and support has been the cause of

my success in completing this.

REFERENCES: [1] www.sciencedirect.com, C. Caputo , Pacifico M. Pelagagge, Paolo SaliniUniversity of L’Aquila, Heat exchanger design

based on economic optimisationAntonio

[2] www.sciencedirect.com,Applied Thermal Engineering 28

(2008) 1798–1805, Design optimization of shell-and-tube heat

exchangers, Andre´ L.H. Costa a,*, Eduardo M. Queiroz b

[3] www.deltathx.com, Industrial Heat Exchangers

[4] R.C.Sachdeva, fundamentals of Engineering Heat and Mass

Transfer. 3rd edition, NEW AGE INTERNATIONAL

PUBLISHERS, page.Num.497

[5] Design data, ABENER Project: Sikalbaha 225 MW ± 10%

Combined Cycle (Dual Fuel) Power Plant Project Bangladesh,

Condenser Design. Performance for Guaranteed Balances

Revision 17/11/2011

[6] Author: Jim Lang (©SDSM&T, 2000), Condenser Design on

Aspen-Plus Software (Heat Exchanger design with a phase

change)

[7] Lang, Jim. “Design Procedure for Heat Exchangers on

Aspen Plus Software” Design Manual. June 1999.

[8] Aspen plus Simulator 10.0-1. User Interface (1998).

[9] KEVIN M. LUNSFORD , Bryan Research and Engineering,

Inc. - Technical Papers, Increasing Heat Exchanger Performance, Bryan Research & Engineering, Inc,Bryan, Texas.

[10]WOLVERINE TUBE HEAT TRANSFER DATA BOOK, ch-1_6-Fouling in Heat Exchangers.

[11] HTRI design manual, Page D6.2.1 (Rev.1)

ABOUT THE AUTHOR

Mr. Mehta Vijay K.

M-Tech Student (Thermal Engineering)

Contact No. +919998443111

E-Mail ID:[email protected]

Address: Surag para,Khetani road, Near Police line,

Vadia Devali-365480, Dist.-Amreli, State-Gujarat

effect of fouling factor

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