ecoSMRT LNG Reliquefaction - gastechevent.com Duckett_Babcoc… · ecoSMRT® LNG Reliquefaction...

ecoSMRT® LNG ReliquefactionAlan Duckett – Sales and Technical Director

Babcock LGE Process

Gastech 2017 – An Improved Reliquefaction System for LNG Carriers

www.babcockinternational.com

ecoSMRT® – Introduction

2 Gastech 2017 – An Improved Reliquefaction System for LNG Carriers

• In July 2015, HHI R&D

invited Babcock LGE

Process to develop a new

and improved LNG

reliquefaction system.

• Improvements in main

engine fuel efficiency and

lower voyage speed create a

need for a cost effective,

easy to operate LNG

reliquefaction plant for

today’s modern LNG

carriers.


ecoSMRT® – Design Challenge

3

Reduce CAPEX

• Deliver higher reliquefaction capacity

• Minimise equipment

• Smaller plant – reduce the footprint

• Reduce installation cost


Reduce OPEX

• Increase efficiency – reduce fuel

consumption

• Minimise rotating equipment for ease of

operation

• Simpler plant requiring less maintenance

Babcock LGE Process took up this challenge and work began in August 2015. The concept

design was completed in April 2016 and patent application (UK 1520951.3) filed in June 2016.

20 months on and we have a fully matured design with Approval in Principle (AiP) by LR and in

progress with DNV-GL.


ecoSMRT® – Existing Reliquefaction Plant

4

Reverse Brayton Nitrogen Plant

• Simple cycle but added complexity of

compander for power recovery

• Low efficiency with poor COP

resulting in high power consumption


Mixed Refrigerant (MR) Plant

• Requires external pre-cooling

• Multiple pieces of rotating equipment

• Risk of oil contamination of the PFHE


ecoSMRT® Main Equipment Selection


Compressor selection criteria

• Positive displacement type

• Appropriate volumetric suction

• Good efficiency

• Robust and reliable design

• Good capacity control

• Good turndown capability

• Low maintenance

Cryogenic heat exchanger selection

criteria

• Multistream capability

• Able to handle flashing flow and

condensation

• Compact design

• Robust and reliable design

• Good turndown capability

Oil-injected

Screw

compressor

Brazed

aluminium

plate-fin

heat

exchanger


ecoSMRT® – Design Development


Existing LNG MR reliquefaction ecoSMRT®

• Removal of secondary refrigeration loop

comprising:

• Screw compressor / motor and oil

management system

• Five heat exchangers

• Additional pressure vessels

• Integrated cooling leads to a much simpler

process and control system

• 40% reduction in footprint

• 50% reduction in maintenance

• Developed to use known and proven

technology (no prototyping)

EXTERNAL

PRECOOLING

INTEGRATED

PRECOOLING

www.babcockinternational.com7 Gastech 2017 – An Improved Reliquefaction System for LNG Carriers

• Process optimisation was carried out to achieve the

highest possible efficiency

• The process parameters / variables considered in the

optimisation were:

• Number (N) of refrigerant components

• 2 pressure levels – the compressor suction and

discharge pressures

• 1 temperature – the precooling temperature

• Therefore, (N+3)-dimensional optimisation problem

was formulated, with efficiency as the objective

function

ecoSMRT® – Design Development – Process Optimisation


• Design basis – BOG pressure and temperature,

condensate temperature, LNG composition, BOG

flowrate etc.

• PFHE optimal temperature approach

• At least 20°C of superheat at compressor suction

• MR freezing temperature at least 10°C below

minimum operating temperature

• All oil-containing MR streams (including inside

PFHE) warmer than −10°C to eliminate potential for

oil freezing

ecoSMRT® – Design Development – Optimisation Constraints


• Purpose-built in-house software developed to carry

out optimisation

• Aspen HYSYS® simulation package

• Engineering expertise and experience

• Process parameters are specially optimised for each

BOG pressure, to ensure the highest efficiency for

every design variation

• All modelling carried out to take into account real key

equipment performance data (e.g. compressor

efficiencies at given conditions)

ecoSMRT® – Design Development - Implementation


ecoSMRT® – Process Visualisation





SMR compression and heat rejection

1. Warm MR gas (>35°C) enters the

compressor suction at low pressure (<10

bara).

2. The MR is compressed to the high

pressure (>20 bara), where oil is injected

to cool the compressor and provide a

seal for compression.

3. Oil is then removed in an oil separator

with coalescers to 10 ppmw.

4. The compressed gas at 100°C is cooled

to 40°C in the aftercooler.

5. Heat in the system is rejected in the oil

cooler and aftercooler.MR compression and heat rejection




Integrated MR precooling

1. The cooled, compressed MR enters top

of PFHE where it is further cooled and

partially condensed.

2. Partially condensed MR is separated into

vapour and liquid fractions in the MR

separator.

3. The liquid fraction is returned to the

PFHE through an expansion valve at

approximately 17°C.

4. The vapour fraction passes through

coalescers, reducing the oil content to

0.1 ppmw, before entering the PFHE.

5. The vapour fraction is then cooled as it

passes through the top of the PFHE

providing integrated precooling.

Integrated MR precooling




LNG BOG

reliquefaction

LNG BOG reliquefaction

1. The vapour fraction passes through the

PFHE and leaves as high pressure

cryogenic liquid.

2. The cryogenic MR is returned to the

bottom of the PFHE through the

expansion valve and a flash separator at

<− 162°C.

3. As the cryogenic MR expands through

the PFHE, it cools the high pressure MR

as well as condensing the BOG.

4. The BOG condensate leaves the

reliquefaction exchanger at −160°C and

is sent back to the cargo tanks.

5. The warm MR is sent back to the

compressor to close the circuit.


ecoSMRT® – Oil Carryover Management


The higher temperature in the ecoSMRT® PFHE prevents oil freezing.

Typical MR system with precooling ecoSMRT® with integrated precooling

2

1

3

4

1

2

3

4

1 BOG after external precooling −10°C

2 MR after external precooling −10°C

3 Liquid MR to PFHE << −10°C

4 Top section of PFHE < −10°C

1 BOG to PFHE +40°C

2 MR after the aftercooler +40°C

3 Liquid SMR to PFHE +17°C

4 Top section of PFHE +35°C


ecoSMRT® Plant Visualisation



ecoSMRT® Plant Visualisation



ecoSMRT® Standard Range


13 kt ship speed

Excess BOG = 1558 kg/h

Reliq capacity = 1.5 tph

COP = 23.1%

Anchoring (fuel gas)



COP = 22.2%

11.5 kt ship speed

Excess BOG = 1884kg/h


COP = 23.1%

Anchoring (HFO)



COP = 21.9%

180k LNGC with X-DF engines (BOG from FGC discharge) – ecoSMRT® SMR16


ecoSMRT® Standard Range



ecoSMRT® Performance Comparison (ME-GI SMR08 1.6 tph)


ecoSMRT® Efficiency Comparison (ME-GI SMR08 1.6 tph)


ecoSMRT® Part-load Efficiencies (ecoSMRT® SMR08 1.6 tph)

Power Requirements – Slide Valve vs VFD Slide valve

• Built-in capacity control

• Simple operation

• Lower capital cost (included as standard)

• Lower efficiency at turndown (higher

power consumption)

Variable Frequency Drive (VFD)

• Additional equipment required

• Additional capital cost

• Increased electrical system complexity

• Higher efficiency at turndown (lower

power consumption)

www.babcockinternational.com22

• Gas chromatograph sampling for initial MR fill and

controlling automatic refrigerant top-up to maintain

optimal plant performance

• Includes Bently Nevada condition monitoring for MR

compressor set

• Oil separator is heat traced for winter operation

down to −10°C

• An optional Variable Frequency Drive (VFD) can be

incorporated to improve performance at part loads


ecoSMRT® Additional Operational Features

www.babcockinternational.com23

THANK YOU FOR YOUR ATTENTION

Contact: Alan R. Duckett

[email protected]

Mobile +82 10 6410 7793 or +44 7785 33 1415


ecoSMRT® the new improved MR

reliquefaction plant for today’s

modern LNG Carrier offering

increased performance with

reduced power consumption,

smaller footprint in a range of

sizes to cover specific owner

requirements.

ecoSMRT® Conclusion

www.babcockinternational.comGastech 2017 – An Improved Reliquefaction System for LNG Carriers

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