Service_Experience_2008.pdf

Service Experience 2008, MAN B&W Engines

ME/ME-C and MC/MC-C Engine Series

Contents:

Introduction

Update on Service Experience, ME/ME-C Engine Series

Hydraulic cylinder unit (HCU)

Multi purpose controller (MPC)

Hydraulic power supply (HPS)

Servo oil system

Update on Service Experience, MC/MC-C Engine Series

Condition based overhaul (CBO) of pistons

CBO of exhaust valves

CBO of bearings

Time between overhaul (TBO) for turbochargers

Conclusion

MAN Diesel • Copenhagen, Denmark

–

Service Experience 2008, MAN B&W Engines

ME/ME-C and MC/MC-C Engine Series

Introduction

The number of electronically controlled

engines in service continues to grow

and, at the time of writing, more than

500 engines are on order or in service.

At the end of 2007, the irst S40ME-B

engine was prototype-tested at STX

in Korea, Fig. 8.1. These tests mark

the beginning of an era where the full

potential of the electronic fuel injection

with “rate shaping” (or “injection proil-

ing”) is utilised on production engines

giving a very attractive NO x /SFOC rela-

tionship.

At the beginning of January 2008,

the irst four LNG carriers with

2 x 6S70ME-C engines (Fig. 8.2) were

in service. During 2008, this number

will increase to 20 vessels.

In addition to the service experience

update for the ME/ME-C engine series,

this paper will describe the recent ser-

vice experience relating to conventional

mechanical issues of MAN B&W two-

stroke engines. The condition-based

overhaul (CBO) concept and an update

on monitoring systems will also be given. Fig. 8.1: 6S40ME-B engine

Fig. 8.2: LNG carrier with 2 x 6S70ME-C engines

Update on Service

Experience, ME/ME-C

Engine Series

FIVA Valve

CCU

At the end of 2007, 10 ME/ME-C en-

gines were in service. The reporting will

be divided into the various sub-systems

of the ME/ME-C engines. These are the

hydraulic cylinder unit (HCU), the multi

purpose controller (MPC), the hydraulic

power supply (HPS) and the servo oil

system.

MPC

4-20 mA

LVDT

Electronic

Requested position

(table) synchronised

to crankshaft position

control

± 9 V

Current

amplifier

± 9 A

Slide pos. [mm]

+6,3

-7

Hydraulic cylinder unit (HCU)

For the HCU, we will concentrate on

two main topics, i.e. the ME control

valves and the exhaust valve actuator

system.

Exhaust valve opening

Injection AC.

Fig. 8.3: FIVA valve position control

ME control valves

ELVA/ELFI valves

(Curtiss Wright supply)

ELVA/ELFI coniguration (one control

valve for exhaust valve actuation and

another control valve for fuel injection

control) are in service on 20 plants.

For the on/off ELVA valve, a modiied

high-response valve is undergoing

service testing. When this service test-

ing is concluded, the 20 plants will be

updated and service issues with the

ELVA/ELFI coniguration will then be

solved.

New

Old

FIVA Valve (Curtiss Wright version)

The feedback loop of the FIVA valve

position control, Fig. 8., has caused

untimed injection and untimed exhaust

valve operation owing to various rea-

sons. These reasons are related to the

FIVA valve itself in some cases, and in

other cases to the part of the feedback

loop in the multi purpose controller

(MPC), see multi purpose controller

chapter.

Fig. 8.4: FIVA valve feedback failure: exchange of analogue voltage regulator with switch

mode voltage regulator

an excessive amount of heat raising the

temperature by 5ºC on the PCB. In

some cases, this caused a temperature

shutdown of the LVDT converter in the

feedback loop, resulting in the above-

described unstable function of the FIVA

valve. The solution was to exchange

the analogue voltage regulator with a

switch mode regulator, Fig. 8.4. Hereby,

the temperature of the PCB was low-

ered by approx. 5ºC.

back signal, improved supervision is

introduced by new software, see multi

purpose controller chapter.

In 2007, we experienced a cylinder cov-

er lift twice on testbed with 6S70ME-C

engines. The reason for these incidents

was untimed movement of the FIVA

valve main slide owing to a drilling chip

left inside the main slide during produc-

tion, Fig. 8.5. After discovering this pro-

duction mistake, we have, together with

the sub-suppliers, cleaned/re-machined

approx. 500 main slides to avoid loose

drilling chips inside the FIVA valves.

In the original version, the electronics on

the printed circuit board (PCB) in the

Curtiss Wright FIVA valve showed

thermal instability causing untimed ac-

tuation of the valve. The reason was an

analogue voltage regulator generating

Furthermore, in order to safeguard

against untimed movement of the FIVA

main slide due to an erroneous feed-

Current

Fig. 8.6 gives an explanation of what hap-

pens if a loose drilling chip is stuck be-

tween the pilot slide and the main slide.

Neutral Position

Increased set point Decreased set point

Chip

Fig. 8.6 (left hand side) shows the valve

in balance. This means that the con-

stant pressure on the bottom of the

main slide is balanced by a pressure

creating a similar force in downward di-

rection, thus keeping the slide in neutral

(“zero”) position.

In order to open the exhaust valve or to

stop fuel injection (Fig. 8.6, centre), the

pilot slide should be moved downward,

thereby increasing the pressure on the

top of the main slide and moving the

main slide downward. This will result in

exhaust valve opening or stop of fuel

injection.

Valve in balance

Exhaust valve open or

stop of fuel injection

Exhaust valve closed

or fuel injection

Fig. 8.6: CWAT FIVA valve: Movement of pilot valve and main slide

When the pilot slide is moved upward

(Fig. 8.6, right hand side), pressure on

the top of the main slide is decreasing

and the main slide is moved upward

enabling closure of the exhaust valve

or fuel injection. If a drilling chip is stuck

in between the pilot and the main slide

when the exhaust valve is closing, there

is a risk of fuel injection just after clos-

ing of the exhaust valve. This will cre-

ate an excessive pressure build-up in

the combustion chamber and a risk of

cylinder cover lifting. This was the cause

of the two cylinder cover lifts on the

6S70ME-C engines on testbed in 2007.

have seen a number of units failing be-

cause of:

FIVA Valve (MAN B&W version)

During 2007, the irst vessels with MAN

B&W FIVA valves controlling ME engines

went into service.

A: Broken bushing for the pilot slide,

Fig. 8.8a. This item was rectiied

during the prototype testing period

The MAN B&W FIVA valve can be seen

in Fig. 8.7. It consists of a valve main

body on which the Parker pilot valve

and the H. F. Jensen feedback sensor

are mounted. For the Parker valve, we

B: Earthing failure owing to damage of

a lexible wire strip inside the valve,

Fig. 8.8b

C: Malfunction owing to failing

operational ampliier, Fig. 8.8c

Loose drilling chip found in valve from unit where cover lift had occurred

Fig. 8.5: CWAT FIVA valve: chips found in main slide

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