Document number 202044 Date of issue 6 May 2016 Product · PDF fileWARTSILA RT-FLEX50 DUAL...

Document number 202044

Date of issue 6 May 2016

Product RT-flex50 conversion to DF generic manual

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WARTSILA RT-FLEX50 DUAL FUEL RETROFIT GENERIC MANUALG

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© Copyright by Winterthur Gas & Diesel Ltd.

All rights reserved. No part of this document may be reproduced or copied in any form or by any means

(electronic,mechanical, graphic, photocopying, recording, taping or other information retrieval systems)

without the prior written permission of the copyright owner.

THIS PUBLICATION IS DESIGNED TO PROVIDE AN ACCURATE AND AUTHORITATIVE

INFORMATION WITH REGARD TO THE SUBJECT-MATTER COVERED AS WAS AVAILABLE AT THE

TIME OF PRINTING. HOWEVER, THE PUBLICATION DEALS WITH COMPLICATED TECHNICAL

MATTERS SUITED ONLY FOR SPECIALISTS IN THE AREA, AND THE DESIGN OF THE SUBJECT-

PRODUCTS IS SUBJECT TO REGULAR IMPROVEMENTS, MODIFICATIONS AND CHANGES.

CONSEQUENTLY, THE PUBLISHER AND COPYRIGHT OWNER OF THIS PUBLICATION CAN NOT

ACCEPT ANY RESPONSIBILITY OR LIABILITY FOR ANY EVENTUAL ERRORS OR OMISSIONS IN

THIS BOOKLET OR FOR DISCREPANCIES ARISING FROM THE FEATURES OF ANY ACTUAL ITEM

IN THE RESPECTIVE PRODUCT BEING DIFFERENT FROM THOSE SHOWN IN THIS PUBLICATION.

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LIABLE FOR ANY FINANCIAL CONSEQUENTIAL DAMAGES OR OTHER LOSS, OR ANY OTHER

DAMAGE OR INJURY, SUFFERED BY ANY PARTY MAKING USE OF THIS PUBLICATION OR THE

INFORMATION CONTAINED HEREIN.


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Preface

The Wartsila RT-FLEX50 DUAL FUEL RETROFIT GENERIC MANUAL is intended as an initial

guide when planning to retrofit a conventional diesel / HFO burning Wartsila RT-flex50

installation for future operation on natural gas. Since each existing installation is unique, this

document shall be seen as a generic check list with main focus on modification work required

on the main engine.

Every retrofit project requires a thorough vessel specific investigation, analyzing the impact and

modification need on: the engine, the engine room ancillary systems, control and alarm systems

and the hazardous zones around gas related equipment and venting pipes.

In parallel to this dual fuel retrofit check list focusing on modifications on the main engine, it is

highly recommended to study the “RT-flex50DF Marine Installation Manual”, to get a better

understanding of the requirements for gas related auxiliary equipment to be installed in the

engine room or on deck.

Winterthur Gas & Diesel Ltd.

Product Information

Schützenstrasse 1-3

PO Box 414

CH-8401 Winterthur

Switzerland

Tel: +41 52 262 07 14

Fax: +41 52 262 07 18

www.wingd.com

http://www.wingd.com/


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Table of contents

1 RT-flex50DF engine output parameters ................................................................................................ 6

1.1 Maximum nominal output difference between conventional flex50-D main engine and

flex50DF main engine. .............................................................................................................................. 6

2 Engine outline comparison ................................................................................................................... 8

2.1 Outline view example of RT-flex50DF engine with turbo charger at aft end ............................... 8

3 DF conversion – influence on built on engine components ................................................................. 9

3.1 Component group categories for RT-flex50-D and RT-flex50-DF engines .................................... 9

3.1.1 Engine component groups common / components remaining unchanged ......................... 9

3.1.2 Engine components groups to be replaced when converting to DF ................................... 11

3.1.3 Engine component groups to be evaluated for each conversion project, the component

groups may need total replacement or partial equipment modification ........................................... 12

3.1.4 New engine component groups to be built on the engine when converting to DF ........... 13

3.1.5 Engine control system ......................................................................................................... 15

3.1.6 DF engine specific tools....................................................................................................... 16

4 DF conversion – essential new components off engine ..................................................................... 17

4.1 New engine room equipment to be taken into consideration when converting to DF ............. 17

4.1.1 Shaft power meter .............................................................................................................. 17

4.1.2 Gas valve unit (GVU) ........................................................................................................... 17

4.1.3 Pilot fuel system .................................................................................................................. 18

5 Engine room systems and equipment ................................................................................................ 19

5.1 Engine room systems and topics requiring attention when converting to DF ........................... 19

5.1.1 Class rules valid at the time of conversion ......................................................................... 19

5.1.2 Safety – gas detection – gas release ................................................................................... 19

5.1.3 HT cooling water expansion tank ........................................................................................ 19

5.1.4 Exhaust gas system ............................................................................................................. 19

6 LNG tank and gas feed system ............................................................................................................ 20

6.1 LNG tanks and gas processing ..................................................................................................... 20

7 Conclusion ........................................................................................................................................... 21

7.1 Conversion of existing Wärtsilä 2-stroke flex installations ......................................................... 21


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1 RT-flex50DF engine output parameters

1.1 Maximum nominal output difference between conventional flex50-D main

engine and flex50DF main engine.

Wartsila 2-stroke DF engines have a lower maximum continuous rating (MCR) compared to similar bore

size liquid fuel burning engines. Since DF technology is based on the Otto combustion principle there are

cylinder pressure MEP limitations persisting, that to avoid knocking / pre-ignition in the combustion

chamber, consequently the maximum available engine output is reduced.

For every conversion project, the vessel’s original propeller characteristics have to be carefully

evaluated and compared to the available engine power after converting to DF. Depending on the

original propeller layout and the originally selected CMCR, diesel burning RT-flex50 installations

converted to gas burning RT-flex50DF installations, may have to accept lower sailing speeds. In certain

cases it may also be necessary to exchange / modify the propeller.

Table 1, Maximum output difference between RT-flex50D and RT-flex50DF

RT-flex50-D RT-flex50DF

Power/cyl. R1 (kW) 1745 1440

Power/cyl. R4 1020 955

Speed R1 (rpm) 124 124

Speed R3/R4 (rpm) 95 99

Bore (mm) 50 50

Stroke (mm) 2050 2050

MEP Introduction (bar) 21.0 17.3

Cyl. config. 5-8 5-8


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The operating field after converting to DF need to be within the operating points outlined with green

lines.

Figure 1, Visual graph of common operating field

Conclusion: It may be necessary to change the propeller when converting to DF.

77%

58%

77%

55%

66%

83%

80%


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2 Engine outline comparison

2.1 Outline view example of RT-flex50DF engine with turbo charger at aft end

The physical installation space requirement is the same for both engine types, except for the upper

platform, which is somewhat lengthened at the free end side for RT-flex50DF engines. The pilot fuel

pump unit is located on the upper platform free end side, making the platform longer, nevertheless, for

conversion projects the pilot fuel pump unit can be relocated and installed on the hull side. Therefore

we consider the space requirements identical regardless of RT-flex50-D or RT-flex50DF.

Below engine illustrations of a 5RT-flex50DF focuses on gas specific components and rerouted piping

installed on the engine.

FUEL SIDE OUTLINE VIEW EXHAUST SIDE OUTLINE VIEW

Figure 2, Fuel side outline view respectively exhaust side outline view

Conclusion: The physical engine space requirements do not change after gas related equipment is

installed.


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3 DF conversion – influence on built on engine components

3.1 Component group categories for RT-flex50-D and RT-flex50-DF engines

Engine components have been categorized into 6 categories. Category 1 indicates components, which all

remain unchanged. Category 2 indicates components that have to be replaced when converting to DF.

Category 3 lists components that will require project specific consideration. Category 3 parts might be

suitable for use in some projects, but might as well need replacement. Category 4 lists DF components

which are not installed on conventional liquid burning engines and are new components to be added on

the engine when converting to DF. Category 5 concerns automation and is applicable to both

automation on the engine, as well as to the remote control and alarm system in the engine control

room. Category 6 focus on items, which as such are not relevant for the DF retrofit, but are important in

order to ensure the possibility to carry out proper maintenance later on.

3.1.1 Engine component groups common / components remaining unchanged

- Bedplate with main bearings

- Thrust bearing

- Engine column

- Drive supply unit

- Column doors

- Air water separator

- Turning gear

- Piston cooling

- Gland box

- Crankshaft

- Connecting rod

- Exhaust gas valve arrangement

- Supply unit arrangement

o Common rail fuel pump

o Fuel pump casing

o Gear wheel

- Servo oil pump

- Auxiliary blowers

Illustration of parts being identical

Figure 3, bedplate Figure 3, gear wheel Figure 5, thrust bearings


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Figure 6, crank shaft Figure 7, gland box Figure 8, turning gear

Figure 9, connecting rod Figure 50, supply unit Figure 41, free end cover Figure 12, crank case explosion relief valves

Figure 6, A-frame


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3.1.2 Engine components groups to be replaced when converting to DF

- Cylinder units

o Cylinder covers

o Pistons

o Piston rod

o Cylinder liner / liner insulation tube

o Cylinder jacket

o Water guide jacket

- Cylinder lubrication

- Fuel injection / exhaust gas drive / servo oil regulation linkage arrangement modification

- Tie rods

- Rail unit

- Fuel rail

- Servo oil rail

- Exhaust gas valve control unit

- Scavenge air receiver explosion relief valve

- Cross head guide shoe

- Bearing shell cross head

- Crank pin bearing shell

Illustrations of parts that need to be exchanged

Figure 75, rail box Figure 94, piston rod, piston Figure 86, cylinder liner

Figure 17, cross head pin and guide shoe

Figure 118, cross head upper bearing cap

Figure 10, air receiver Figure 20, water guide jacket


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3.1.3 Engine component groups to be evaluated for each conversion project, the

component groups may need total replacement or partial equipment modification

- Turbo charger

- Exhaust gas manifold

- Scavenge air receiver

- Scavenge air cooler

- Air piping

- High pressure fuel piping

- Water piping

- Oil piping

- Measuring and instrumentation detection

- Cylinder block (requires machining or replacement)

- Starting air valve

- Cross head bearing lubrication pump (mandatory for DF engines, project specific for

conventional liquid burning engines)

- Control box for local maneuvering

Illustrations of parts that may need replacement or modifications

Figure 22, turbo charger Figure 23, scavenge air cooler

Figure 24, control panel for local maneuvering

Figure 212, exhaust gas manifold


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3.1.4 New engine component groups to be built on the engine when converting to DF

- Gas admission valves

- Gas supply pipe manifold

- Pilot fuel oil supply injectors

- Pilot fuel oil supply pump and piping

- Exhaust gas waste gate

- Piston underside gas detection system

Figure 25, essential new components. Pilot fuel pump (blue), pilot fuel pipes (blue) and gas pipe manifold (yellow).


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Figure 26, gas admission valves with hydraulic pipes

Figure 27, gas pipe manifold mounted on engine


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3.1.5 Engine control system

RT-flex50DF control is based on “UNIC” meanwhile conventional RT-flex50D are based on “flex” control

technology.

When converting a conventional RT-flex50-D engine to RT-flex50DF all electrical and automation

systems and their components need to be updated for UNIC compatibility.

Sensors and automation components applied on engines to be converted need to be checked for UNIC

compatibility.

Remote control and alarm and monitoring systems (off engine) need to be replaced or updated for UNIC

compatibility.

Figure 27, UNIC based


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3.1.6 DF engine specific tools

The majority of engine related tools delivered for an RT-flex50-D engine can be used after converting to

DF. Only a small number of tools need to be replaced or modified.

Short list of important tools to be replaced or modified:

- Piston assembly lifting tool

- Piston measuring tool

- Piston ring assembly tool

- Fuel injector test bench (adaptation)

- Cylinder liner insulation tool

- Tie rod pre-tensioning tool

- Injection valve grinding tool

- Software download package tool

- Tool emergency cylinder lubrication

- Tool for gas admission valve (new)

Other tools may be concerned but need to be evaluated on a project by project basis.

Short list of tools requiring project specific investigation:

- Scavenge air cooler lifting tool

- Turbo charger tools


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4 DF conversion – essential new components off engine

4.1 New engine room equipment to be taken into consideration when converting

to DF

This document focuses mainly on modifications on the engine, but some few pieces of equipment

being essential for functionality will be mentioned.

4.1.1 Shaft power meter

On conventional Wärtsilä 2-stroke flex engines a number of engine operating parameters are

used for calculating a fairly accurate power output estimate. The estimated power output is

sufficient feedback for injection control of correct liquid fuel amount.

Duel fuel engines operating in gas mode require a more accurate engine load feedback signal.

Therefore a shaft power meter has to be installed to provide the engine’s actual load feedback

signal.

Shaft power meters are not mandatory on board conventional liquid fuel burning vessels and

may or may not be installed. In case a shaft power meter is already installed, it can most likely

provide the necessary engine load feedback signal required for DF engines operating in gas

mode.

Figure 28, example of shaft power meter

4.1.2 Gas valve unit (GVU)

The required gas pressure before the gas admission valves varies with the engine load. To

accurately control the gas pressure before the gas admission valves, a gas pressure regulating

valve is required. Wärtsilä offers suitable gas valve units of open or enclosed type. When


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selecting an enclosed type gas valve unit it becomes a part of the double wall gas piping and can

be installed inside the engine room, meanwhile an open type gas regulating unit must be

installed in a dedicated gas valve room.

Figure 29, GVU

4.1.3 Pilot fuel system

MDO fuel feed pumps, filters and equipment for pilot fuel feed system have to be added to the

engine room ancillary equipment.

Figure 30, GVU-EDTM

Figure 31, Pilot fuel system


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5 Engine room systems and equipment

5.1 Engine room systems and topics requiring attention when converting to DF

This document focuses mainly on conversion modifications on the engine, but some few pieces of

engine room equipment being essential for functionality and safety will be mentioned.

For more detailed information reference is made to the Marine Installation Manual (MIM).

5.1.1 Class rules valid at the time of conversion

Compliancy to class rules has to be assured. Every vessel conversion has to be engineered in

close cooperation with the class.

5.1.2 Safety – gas detection – gas release

Attention has to be paid to safety. With double wall gas piping the engine room is considered a

gas safe machinery space, single failure will not lead to gas release into the machinery space. To

monitor that no gas leakage occurs, gas sensors have to be installed in the engine room. The

number and position of the gas sensors have to be confirmed by the class.

The annular space between the double wall pipes has to be continuously ventilated, as per class

requirements.

Any potential intended or unintended release of gas has to be diverted to a hazardous zone

outside the engine room. Released ignitable gas will dilute quickly to a concentration level

below the lower explosion level (LEL).

Auxilliary systems shall be designed with focus on mitigating the impact of a potential

malfunction.

5.1.3 HT cooling water expansion tank

Separated cooling water low temperature and high temperature expansion tanks are

recommended for DF installation. During an abnormal engine operation (crack in cylinder liner,

exhaust gas valve cage or pilot fuel pre-chamber) it may be possible that the HT water circuit

gets contaminated with gas, ending up in the high temperature cooling water expansion tank.

The HT cooling water expansion tank has to be of closed type and classification societies might

require a gas detector to be installed in the expansion tank, as well as extending the venting

pipe to appropriate place.

5.1.4 Exhaust gas system

The exhaust gas pipe shall be designed in such way that gas cannot accumulate in the exhaust

system. Measures have to be taken to prevent damages in case gas would accidently enter the

exhaust gas piping and cause an explosion in the exhaust gas pipe. There are two possible safety

measures to mitigate the impact of an explosion in the exhaust gas piping, both alternatives are


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based on pressure release in case of an explosion. Over pressure safety devices to be installed in

the exhaust gas piping can be rupture discs (requiring separate exhaust ducts releasing exhaust

gasses outside the hull after rupture), or spring loaded exhaust gas relief valves. The number

and position of pressure relief devices are installation dependent.

6 LNG tank and gas feed system

6.1 LNG tanks and gas processing

This document focuses mainly on conversion modifications on the engine. Each conversion

project requires a detailed study focusing on the LNG tanks and gas processing equipment.

Factors to consider when determining the LNG tank design and size are:

- Vessel operating profile, days of autonomy between each LNG tank fill up

- Positioning of LNG tanks on the existing vessel?

- Where can compressors and re-gasification equipment be installed?

Wärtsilä offers LNGPacTM solutions with the following benefits:

- Type C pressure vessel. Design pressure 6-9 bar.

- Pressurised or cryogenic pump based gas feed solution.

- Vacuum (MLI and Perlite) or polyurethane insulation.

- Horizontal, vertical, longitudinal and transversal placing.

- LNG process equipment located inside built-on tank connection space or deck mounted

vaporising skid.

- Class approved safety and control system.

- Remote actuated and manually operated cryogenic valves.

- Dedicated control and monitoring system.

Figure 32, LNGPacTM


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7 Conclusion

7.1 Conversion of existing Wärtsilä 2-stroke flex installations

Conversion of existing liquid fuel Wärtsilä 2-stroke installations is possible, thereby enabling the ship

owners to enjoy the benefits operating on gas as fuel. When operating in gas mode the emission

benefits are:

Low NOx emissions, Tier III compliancy without exhaust gas after treatment

Particulate matter emissions reduced to close to zero

No SOx emissions

Document number 202044 Date of issue 6 May 2016 Product · PDF fileWARTSILA RT-FLEX50 DUAL...

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