Topic

Values and benefits of improving the

performance of heat exchangers

Presented by :

Martin Gough, Managing Director,

CALGAVIN Ltd

>The answer must include…

Least risk

Cost effective

Proven technology

‘Every plant wants to save

energy but how can this be

achieved with existing plants?’

High energy savings = Unrealistic high

CAPEX

> Energy studies/Heat Transfer

models do not identify operational

issues such as

Fouling

Underperforming exchangers

Under-designed exchangers

Maldistribution

Available space

Mechanical problems (e.g.vibration)

Corrosion/Erosion

Control issues

> Tubeside heat transfer enhancement system

Direction of Flow

Empty tube- cooling viscous process fluid

>Flow stratification

Maldistribution problems

Effects of hiTRAN Thermal Systems

FOULING: Threshold Models

Reduced Wall Temperatures

Increased Shear Stress

Reduced Fouling

Lessons learned:

-0.2

0

0.2

0.4

0.6

0.8

1

-10 -5 0 5 10

> hiTRAN tube side velocity profile with increased shear

Velocity profile hiTRAN Re = 500

Radial position [mm]

hiTRAN measured

Re = 500

Turbulent theory

Re > 10000

Laminar theory

Re < 2300

U / Umax [-]

Velocity profile near to

the wall similar to

turbulent flow even

under laminar

conditions

Shear stress distribution with hiTRAN Thermal Systems

hiTRAN loop

Water

Reynolds [-] 30000

Density [kg/m3] 1000

Velocity [m/s] 2.06

f-factor [-] 0.012

Plain shear stress [Pa]

12.7

CALGAVIN Global Accomplishments Case Studies

Double Enhanced Helical baffle / hiTRAN Dalia FPSO

Client: Total Oil, Angola

Contractor: Saipem s.a.

Exchanger: Interchanger Top Deck of FPSO

Tubeside Fluid: Dry Crude (87.5 C to 70.1C)

Shellside Fluid: Wet Crude (50.5 C to 60.7 C)

Problem -

High Viscous dry crude limits heat transfer, Laminar flow conditions conducive to fouling, limited plot

space/weight available

Plant Improvement – CALGAVIN Solution/Benefit

• Reduced exchanger size/plot space from 9 shells to 2

• Four fold increase in overall heat transfer

• Uniform flow velocity and improved distribution - Reduced fouling

Size comparison - Conventional / HELITRAN

plain /

single.Segme

ntal.

hiTRAN® /

helical

baffle

gain

OHTC [W/m2K] 59.9 242.7 4x

Tube side:

HTC [W/m2K] 95 770 8x

dp [bar] 140 150

Flow velocity [m/sec] 0.92 0.45 ½

Reynolds [-] 1680 800 ½

Residence time [sec] 102 27 ¼

Shell side

HTC [W/m2K] 455 789 ~2

dp [bar] 1.50 1.25

Flow velocity [m/sec] 0.41 1.3 3

Reynolds 250 635

Wall temperatures [°C] 59.2 65.6

Geometry

Shell in series [-] 3 1

Shell in parallel [-] 3 2

Total no. of Shells [-] 9 2 ~4

Tube Flow path [m] 94.5 12.2 1/8

Tube length [m] 5.25 6.096

Total tube count [-] 16002 3640 ~¼

Tube passes [-] 6 2

Total HT area [m2] 6420 1704 ~¼

Plot space [m2] 104.5 26.2 ¼

Weight wet [kg] 401148 130716 1/3

Exchanger costs [%] 100 35 ~1/3

Conventional HELITRAN

Helical baffle on outside

hiTRAN tubeside

Feed/Effluent Exchanger Enhancement

Client: LUKOIL, Volgograd, Russia

Contractor: N/A

Exchanger: TEMA AES with Helical baffles

Tubeside Fluid: Reactor Effluent (308 C to 115C)

Shellside Fluid: Crude/Hydrogen gas mix (44.8C to 240C)

Problem –

High fuel consumption caused by limited performance, hindering plant

capacity increase.

Plant Improvement – CALGAVIN Solution/Benefit

• Reduced Maldistribution improved exchanger performance

• Recovered 4.6MW of energy on the fired heater at full flow

• Fuel Saving of US$233,000 per annum at original flow rate, enabling higher throughput

hiTRAN installation and benefits

before (empty) after (hiTRAN)

Tube pressure drop 25mbar (>85% nozzles) 200mbar (~10% nozzles)

Tube side heat transfer <285 W/m2K ~980W/m2K

Shell feed outlet temp 240C 314C

Tube effluent outlet 115 82

Mass flow 27kg/sec 42kg/sec

Load on fired heater 4.2MW 2MW

Annual energy savings of $ 233000

Crude Exchanger

Client: Pemex, Mexico

Contractor: EIGSA

Exchanger: Preheat train

Tubeside Fluid: De-salted Crude (59.5 C to 53.5C) Shellside Fluid: Wet Crude (33.6 C to 39.3C)

Problem -

New plant where heat exchanger costs were appearing excessive in design phase, hindering commission process.

Plant Improvement – CALGAVIN Solution/Benefit

• Reduction from original train design of 20 shells down to 8. • Saving significant plot space and capital cost. • Approximate saving in excess of US$2 million.

Original Design

2 shells in series, in 5 parallel rows

for each train.

hiTRAN Enhanced

4 shells in parallel for each train,

reduced size exchangers

Original Design compared to hiTRAN enhancement - 2 Trains

>Thank you for listening

Any Questions?