Wartsila 31 Product Manual Download

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Idle

Intermediate

Rated

Speed

C1: Variable -speed and
-load auxiliary engine
application

100

Torque
(%)

0.15

0.1

0.15

Weighting
factor

Engine family/group

As engine manufacturers have a variety of engines ranging in size and application, the NO

Technical Code allows the organising of engines into families or groups. By definition, an
engine family is a manufacturer’s grouping, which through their design, are expected to have
similar exhaust emissions characteristics i.e., their basic design parameters are common.
When testing an engine family, the engine which is expected to develop the worst emissions
is selected for testing. The engine family is represented by the parent engine, and the
certification emission testing is only necessary for the parent engine. Further engines can be
certified by checking document, component, setting etc., which have to show correspondence
with those of the parent engine.

Technical file

According to the IMO regulations, a Technical File shall be made for each engine. The Technical
File contains information about the components affecting NO

emissions, and each critical

component is marked with a special IMO number. The allowable setting values and parameters
for running the engine are also specified in the Technical File. The EIAPP certificate is part of
the IAPP (International Air Pollution Prevention) Certificate for the whole ship.

IMO NOx emission standards

The first IMO Tier 1 NOx emission standard entered into force in 2005 and applies to marine
diesel engines installed in ships constructed on or after 1.1.2000 and prior to 1.1.2011.

The Marpol Annex VI and the NO

Technical Code were later undertaken a review with the

intention to further reduce emissions from ships and a final adoption for IMO Tier 2 and Tier
3 standards were taken in October 2008.

The IMO Tier 2 NOx standard entered into force 1.1.2011 and replaced the IMO Tier 1 NOx
emission standard globally. The Tier 2 NOx standard applies for marine diesel engines installed
in ships constructed on or after 1.1.2011.

The IMO Tier 3 NO

emission standard effective date starts from year 2016. The Tier 3 standard

will apply in designated emission control areas (ECA). The ECAs are to be defined by the IMO.
So far, the North American ECA and the US Caribbean Sea ECA have been defined and will
be effective for marine diesel engines installed in ships constructed on or after 1.1.2016. For
other ECAs which might be designated in the future for Tier 3 NOx control, the entry into force
date would apply to ships constructed on or after the date of adoption by the MEPC of such
an ECA, or a later date as may be specified separately. The IMO Tier 2 NO

emission standard

will apply outside the Tier 3 designated areas.

The NO

emissions limits in the IMO standards are expressed as dependent on engine speed.

These are shown in the following figure.

Wärtsilä 31 Product Guide - a1 - 18 October 2016

12-3

12. Exhaust Emissions

Wärtsilä 31 Product Guide