Marine Nitrogen Generators– enabling intelligent tank venting

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Introduction

Contents

PSA technology 3

Overall design 6

Main features 8

Benefits 10

Specifications 12

Applications 13

Safety and compliance 14

Service and maintenance 15

Pres-Vac Marine Nitrogen Generators are a product of Pres-Vac Engi-neering ApS, which has more than 60 years' experience in tank venting systems. The marine nitrogen generators are the latest products in our range of advanced tank venting solutions.

Pres-Vac Marine Nitrogen Generators provide systems for the marine- and off-shore industry, which demands clean, dry nitrogen of high purity for inerting, blanketing and purging.

Using Pres-Vac Marine Nitrogen Generators results in a cost reduction of 30-70% compared to conventional nitrogen generators. Safety, reliability, simple installation and a small footprint characterise our systems.

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PSA technology

Pressure swing adsorption (PSA) and membrane gas separation are the two most common technologies available when producing on-site nitrogen. Flue gas systems can also be used for inerting cargo tanks. However, due to the high level of impurities in flue gas, the use of these systems is limited to crude oil cargoes and can be excluded when transporting clean cargoes, that are vulnerable to contamination.

Traditionally, most nitrogen generators have been based on mem-brane technology, but PSA technology has proven to be superior, offering numerous operational advantages and greater cost efficiency. Today, PSA technology is regarded as the technology of the future, when it comes to the on-site production of nitrogen.

In existence for over 100 years, PSA technology is used exten-sively for various on-shore applications. Compared to convention-al membrane technology, PSA technology is significantly simpler and much more energy efficient, resulting in large savings on overall operational costs.

The base material used in the PSA process is carbon molecular sieve (CMS), which is a non-toxic, non-flammable carbon-based material processed into a porous material using various additives. A stable, passive material, CMS is not consumed and does not wear down or deteriorate when producing nitrogen.

At ambient air pressure, CMS does not react to air. When exposed to 6-10 bars of pressurized air, however, CMS starts adsorbing (capturing) oxygen molecules and allows nitrogen to pass.When pressure is reduced, the adsorption process stops and the oxygen molecules are released from the porous surface of the CMS.The efficiency of CMS in the Pres-Vac Marine Nitrogen Genera-tor remains constant over the entire system life cycle. The CMS material has a designed lifetime of more than 40,000 operation hours.

CARBON MOLECULAR SIEVE - CMS

CMS CHARACTERISTICS

No deteriorations Non-flammable Non-toxic Lifetime of more than 40,000 operation hours Pellet size: 2-5 mm

PRESSURE SWING ADSORPTION (PSA)

PSA technology

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A PSA system requires a minimum of two identical pressure ves-sels filled with CMS. One pressure vessel is always in nitrogen producing mode, while the other is in recovery mode. After about one minute, the pressure between the two vessels is equalised. Subsequently, the modes swing and when the vessel is in recov-ery mode, it enters production mode and the pressure vessel in production mode enters recovery mode.

This alternating process is referred to as pressure swing adsorp-tion.A sequence controlled valve system distributes compressed air into the pressure vessel, as described below.

PSA production mode – pressure vessel 1 Exhaust valve C1 is closed and Outlet valve A1 and Inlet valve

D1 open. Compressed air starts to flow through the pressure vessel 1. Oxygen is captured by the CMS and the nitrogen leaves the

pressure vessel through N2 outlet. After approximately one minute the production mode stops

and Outlet valve A1 and Inlet valve D1 close.

PSA recovery mode – pressure vessel 2 Outlet valve A2 and Inlet valve D2 are closed and Exhaust

valve C2 opens. A small flow of nitrogen from tank 1 is purged into the top of

tank 2, flushing the oxygen adsorbed by the CMS out of the tank via Exhaust outlet.

D1

N2 outlet

A2

Exhaust outlet

Air inlet

C1

B

A1

21

C2

D2

5

PRESSURE SWING ADSORPTION (PSA)

O2 N2

O2N2

Exhaust outlet

Exhaust outlet

N2

Compressed air

CMS

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Overall design

NITROGEN PROCESS MODULEFLEXIBLE DESIGN

The main components in the nitrogen process module are: PSA adsorption modules, control system, oxygen analyser, flow regulators and control valves. The nitrogen process module is standard skid mounted and both coal tower and pre-micron filter are also mounted on the skid for customer convenience. The PSA units can also be delivered as split units. This will ena-ble individual location of the components in the nitrogen supply module and thereby safe installation space – making Pres-Vac Marine Nitrogen Generators ideal for retrofitting.

Pres-Vac Marine Nitrogen Generators are delivered as complete system packages using a standard hardware platform. The system comprises two main modules:

Air supply module Nitrogen process module

Delivered pretested and ready to use with few external con-nections and minimised cabling, the modules can be installed quickly and easily.

Dry air outlet from 0-10 barsN2 outlet High purity nitrogen flows from PSA 0.13-0.17 bars

N2 outlet High purity nitrogen flows from PSA 0-10 bars

PSA Porous CMS material adsorbs oxygen molecules

Filters Remove particles from compressed air

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Main components in the air supply module: Compressors Air dryers Coal tower Pre-micron filters

The coal tower and the filters are physically located on the PSA unit.

Compressors and air dryers are delivered as stand-alone units, which can be installed at individual locations.

Compressors and air dryers are advanced systems. Developing and producing them is thus limited to a number of highly special-ised international companies.

Because Pres-Vac is not associated with any specific manufac-turer, we are able to meet the preferences of our customers and thus deliver air packages from all major manufactures.

AIR SUPPLY MODULE

Compressor Increases air pressure to required level from 4-12 bars

Air dryer Removes moisture from air by condensation of the compressed air

Coal tower Absorbs fractional impurities and oil particles from the inlet air

Dry air outlet from 0-10 bars

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Air inlet pressure From 4-12 bars

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Main features

A limited number of physical interface points means quick and easy installation 14 different standard systems

Capacity range: 75-10,000 Nm3/h N2 purity range from 95-99.999% Voltage 3 x 380/440V, 50/60 Hz Flow control of outlet flow and pressure.

Ideal for retrofitting The PSA unit can be delivered as split components, which

enables individual placement and utilises limited space optimally.

Compact design and simple installation Modest footprint. Easy integration – few external connections. Minimised cabling provides quick and easy installation. No receival- or buffer tanks required. Modular system components.

High performance Low power consumption due to effective system utilisation. Reduced investments in onboard generator capacity. Avoidance of critical overload and blackouts. Optimised off-loading conditions shorten discharge time

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A limited number of physical interface points means quick and easy installation 14 different standard systems

Capacity range: 75-10,000 Nm3/h N2 purity range from 95-99.999% Voltage 3 x 380/440V, 50/60 Hz Flow control of outlet flow and pressure.

Advanced hardware Dry air supplied to e.g. ballast tanks Low noise exhaust silencer below 82 dB(A) Alarm monitoring of filters for increased safety Angle seated valves for more precise PSA sequence control

Operation Easy and intuitive touch screen operator interface. Fully automatic control system offering various operational

modes Modbus communication enables easy integration with cargo-,

alarm- and control systems Remote condition monitoring and optimisation via built-in

modem

Wear and tear System efficiency remains constant over entire life cycle CMS material does not deteriorate – no replacement or up-

grades required Few components mean less mechanical wear Dry air means no interior corrosion

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Benefits

+ Lower investment costs and safer operationNitrogen generators normally operate with other heavy energy consumers (e.g. engine, cargo and ballast pumps). Consequently, allocating sufficient electric power without compromising the limits of the vessel’s generator system is often a challenge. The significantly lower power consump-tion of Pres-Vac Marine Nitrogen Generators compared to conventional membrane systems means the size of the switchboard and generators can be considerably reduced in most cases.

For example, the power consumption of a Pres-Vac 4,500 Nm3/hour@95 nitrogen generator is 1,030 kW. A conven-tional membrane-based nitrogen generator with the same capacity has a power consumption of 1,460 kW. Consequently, using a Pres-Vac system reduces a vessel’s power demand by 430 kW.

One more substantial advantage is that a lighter load on the switchboard and generators reduces the likelihood of overloading and blackouts.

A reduced power demand means smaller generators. In the above example, the generator power costs are roughly 500 USD/kW. The capital expenditure savings could be approximately 220,000 USD.

Lower operational costs (OPEX)A Pres-Vac Marine Nitrogen Generator consumes as little as0.23 kW per produced m3 nitrogen at a purity of 95%. Conventional membrane systems consume 42% more energy at same purity.At a purity of 99.9%, the power consumption of a conven-tional membrane system is up to 85% higher compared to a Pres-Vac Marine Nitrogen Generator system.

For example, operating a Pres-Vac 4,500 Nm3/hour@95% nitrogen generator 1,500 hours a year can result in savings of approximately 705,000 kWh per year.

Assuming that the on board production cost of a kWh is0.25 USD/kWh, OPEX can be reduced by 160,000 USD/year.

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+ Lower maintenance costsCMS is a passive substance and does not degrade or dete-riorate when producing nitrogen. The efficiency of the CMS in the Pres-Vac Marine Nitrogen Generator remains constant over the entire system life cycle. The CMS does not need to be replaced or upgraded.

Maintenance is limited to daily inspections and yearly replacement of filter cartridges. Depending on the manufac-turer, compressors normally require service at 3,000-hour intervals. In conventional membrane-based systems, the vulnerability of the membranes makes them consumables. Mechanical and biological contamination gradually reduces their effi-ciency. Consequently, the capacity of a membrane system slowly decreases, resulting in the need for its replacement every five to seven years.

Less efficient membranes entail an increase in operational costs as more energy is required to maintain a constant capacity. The estimated cost of replacing membranes is about 35% of the system’s total cost upon installation. Any off-hiring during retrofitting of membranes could also gener-ate loss in vessel earnings.

0.0

0.5

1.0

1.5

2.0

MembraneN/A

95 99 99.9 99.998 Purity N2%

kW/m3 N2

PSA vs. membrane – difference i power consumption

PSA

Membrane

99.998 Purity N2%

Capacity m3/h N2

System capacity at different purities

95 99 99.9

4,500

3,375

2,250

1,125

0

0

500

1.000

1.500

2.000

2.500

3.000

3.500

4.000

4.500

5.000

1 2 3 4 5 6 7

Series1

PSA

Membrane

MembraneN/A

10 1111

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Specifications

Model Standard Capacity Number of compressors Number of dryers Number of PSA units

PV 10 75 Nm3/hour@95%

PV 20 110 Nm3/hour@95%

PV 30 160 Nm3/hour@95%

PV 40 280 Nm3/hour@95%

PV 50 450 Nm3/hour@95%

PV 60 600 Nm3/hour@95%

PV 70 900 Nm3/hour@95%

PV 80 1,250 Nm3/hour@95%

PV 90 1,800 Nm3/hour@95%

PV 100 2,300 Nm3/hour@95%

PV 110 3,500 Nm3/hour@95%

PV 120 4,500 Nm3/hour@95%

PV 130 5,800 Nm3/hour@95%

PV 140 7,000 Nm3/hour@95%

STANDARD SYSTEM RANGE

Air supply module

Non hazardous area Non hazardous area

Nitrogen process module

Power supplyFresh water coolingAir inlet

Dry air outlet(optional)

Air dryer

Pre-micron filters

Aircompressors

PSA adsorption vessels

N2 outlet

Deck storage vessel (optional)

Oxygen analyser

Post-micronfilter

Nitrogen flowregulator

Carbon tower

Hazardous area

Double blockand bleed(optional)

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Applications

Inerting cargo tanks during discharge Blanketing cargo tanks Purging pipelines

Blanketing tanks during discharge Purging Purging drill mud

Blanketing tanks during discharge Purging Purging drill mud

Inerting cargo tanks during discharge and tank repair

Blanketing cargo tanks Purging pipelines

Inerting cargo tanks during discharge Blanketing Purging pipelines BOP supply

OIL AND PRODUCT TANKERS

SUPPLY VESSEL

GENERAL PURPOSE

LEG, LPG & LNG CARRIERS

DRILLING AND OFF-SHORE

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Safety and Compliance

Safety. Compliance. Performance.Safety and regulatory compliance go hand in hand. Based on a firm under-

standing of the rules and requirements, Pres-Vac products are developed to

pass approval processes and to operate for many years.

REGULATORY COMPLIANCE

Pres-Vac Nitrogen Generators comply with all relevant standards. Our goal is to be best in class .

IMO COMPLIANCE

Pres -Vac Nitrogen Generators comply with the IMO International Convention for the Safety of Life at Sea (SOLAS).

CLASS COMPLIANCE

Pres-Vac Nitrogen Generators complies with rules from major classification societies.

MED MARK OF CONFORMITY - “WHEELMARK”

Marine equipment can only be installed onboard ships flying the flag of an EU country, Norway or Iceland (EFTA countries), or other flag states if marked with the MED Mark of Conformity. Pres-Vac Marine Nitrogen Generators comply with the most recent amendment of MED 96/98/EC. Pres-Vac Marine Nitrogen Generators are listed in the MarED Product Database.

NOISE COMPLIANCE

Pres-Vac Marine Nitrogen Generators comply with the Code on Noise Levels on Board Ships.

DESIGN AND MANUFACTURING

All of our models incorporate the requirements of leading agen-cies. Every order undergoes a design assessment by a selected agency. Pres-Vac Marine Nitrogen Generators are designed and manufactured according to PED (97/23/EC), ISO 9001 (Quality) and ISO 14001 (Environmental), certified by Apragaz

FACTORY ACCEPTANCE TEST - FAT

FAT inspections ensure that the system is built according to pre-approved design documents and cover testing, scope, sup-ply, manufacturing processes, functionality and performance.

When the FAT report is approved, the system is shipped to the yard for installation and commissioning.

COMMISSIONING

Commissioning, which is conducted in the yard, ensures that the system is installed and lives up to the FAT.Participation in Sea Acceptance Test (SAT) is optional.

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Pres-Vac locations

Certified Pres-Vac Service Centers SRC

Upcoming Service Centers

Active in the marine market since 1952, Pres-Vac has estab-lished an extensive worldwide network that also includes various international service and repair centres in strategic marine hubs. The technical skills and marine experience these centres have in repairing Pres-Vac equipment allow us to provide a high level of service for all our customers.

Conveniently located around the world, our Service Repair Centres permit rapid access to spare parts and qualified service repair engineers.

The number of Service Repair Centres is steadily growing and new locations will appear in the near futu.

Service and Repair Centre skillsOur service engineers have been trained and certified to overhaul Pres-Vac products according to our specifications. Our engineers carry individual Pres-Vac ID cards, so you know you are getting the service you trust and expect.

Dynamic Performance and Monitoring SystemPres-Vac is currently developing a dynamic maintenance and per-formance system (DMPS). A built-in modem enables both users and Pres-Vac to retrieve system process and performance data. System data are retrieved and analysed on a regular basis, while the system performance is compared to previously recorded data to determine whether the system should be adjusted.

This approach will ensure that the nitrogen system remains 100% operative and that it will constantly deliver the best performance possible. Performance data are also used for preventive main-tenance, enabling online adjustments and live advice in order to avoid failures or malfunctions in a timely manner.

Pres-Vac Service Repair Centres Pres-Vac locations

NETWORK OF SERVICE REPAIR CENTRES

Service and Maintenance

Pres-Vac Engineering ApSSvanevang 3-5 DK-3450 AllerødDenmark Tel. +45 48 17 40 55Fax +45 48 17 17 88 Email presvac@pres-vac.comWebsite www.pres-vac.com

nitrogen

About Pres-Vac Engineering ApS

For more than 60 years, Pres-Vac Engineering has been supplying pressure/vacuum valves and venting equipment to the tanker shipping industry.

Today, we are the worlds’ leading supplier of intelligent tank venting and roughly 50% of all tanker vessels world-wide use Pres-Vac equipment.

We work with shipyards, naval architects and other partners on all continents. We have a network of highly professional, experienced agents and distributors in all major ship own-ing and ship building countries.

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