CIMAC Congress - Schiff & Hafen

CIMAC CONGRESS | BERGEN 2010
15:30 June 15th Room Scene GH
(3–6) Environment, Fuel & Combustion –
Diesel Engines – Emission Reduction
Sailing towards IMO Tier III – Exhaust
after treatment versus engine-internal
technologies for medium speed diesel
engines
G. Tinschmann, D. Thum, S. Schlueter, P. Pelemis,
G. Stiesch, MAN Diesel & Turbo SE, Germany
Large engines capable of burning heavy fuel oil (HFO) offer
unrivalled effi ciency in operation, long maintenance intervals
and thus hold a dominant market share of over 95% as
propulsion engines in merchant shipping. Taking into account
of the tonnages transported ships are the most economical and
lowest emissions means of transport. However, the proportion
of shipping related emissions of oxides of nitrogen (NOx) und
oxides of sulphur (SOx) is increasing constantly, especially on
shipping routes with a high traffi c concentration and in ports.
Issued by the International Maritime Organization (IMO), with
MARPOL 73/78 Annex VI the fi rst internationally valid piece of
legislation for the limitation of gaseous harmful emissions from
marine diesel engines came into force in 2005, retroactively to
1st January 2000 and is by now titled IMO Tier I in relation to
its NOx limits. Scheduled for 2011, IMO Tier II targets for a 15
- 22% reduction in the NOx limits to be complemented in 2016
by IMO Tier III which calls for the application of a reduction in
NOx emissions of 80% compared with today’s standard in
certain waters yet to be defi ned – so called Emission Control
Areas or “ECA’s”. For the reduction of sulphur oxide (SOx)
emissions from marine engines IMO has nominated SOx-
Emissions Control Areas (SECAs). In these zones, only fuels
with a maximum sulphur content of today 1.5% may be used or
the ship operators are required to employ an equally effective
exhaust aftertreatment. Since the sulphur content of the fuel has
an enormous infl uence on the particulate emissions of an
engine, with the introduction of Annex VI the maximum
sulphur content of marine fuels will be further limited not just
for the ECA’s but worldwide. To fulfi l the limits set by the IMO
MAN Diesel is focussing on technologies which are best to meet
the requirements. On the one hand engines have to fulfi l IMO
Tier II limits on the free ocean and it is allowed to burn heavy
fuel oils with up to 3.5% sulphur until 2020. On the other hand
NOx emissions must be 80% below IMO Tier I inside the ECA’s
and low sulphur fuel has to be used or equivalent techniques
for reducing the SOx-Emissions have to be applied. This paper
describes investigations carried out at MAN Diesel SE and deals
with the following questions and tasks:
• What is the preferred technology for IMO Tier III having the
lowest capital and operational expenditures in mind?
• Is exhaust gas aftertreatment with an SCR catalyst the
preferred solution to reach the NOx-limits or are there
alternatives like Miller-Cycle, exhaust gas recirculation and wet
methods? Are these options technically feasible and
competitive?
• Is a fl exible engine necessary, switching from Tier II to Tier
III operation when entering ECA’s?
• What’s the benefi t of an exhaust gas scrubber and which are
the major challenges if we use HFO also in ECA’s?
• What is the preferred solution for a small genset engine and
which is the favourite for large propulsion engines?
After giving a short overview of technical solutions including
test results, the paper summarizes the challenges and concludes
with the evaluation of several Tier III technologies..
58
Ship & Offshore | 2010 | No. 3
Exhaust emission control of Mitsubishi UE
diesel engine
A. Miyanagi, K. Watanabe, J. Yanagi, Mitsubishi
Heavy Industries, Ltd., Japan
This paper shows our approach and perspective to exhaust emission
control of Mitsubishi UE low speed two-stroke diesel engine for
marine propulsion. Regulations for the emission from marine diesel
engines are tightened still further. IMO Tier II regulation requires
nitrogen oxides to be reduced approx. 15% by 2011 and Tier III
requires them to be reduced 80% by 2016. Sulfur oxides are required
the phased reduction of sulfur content in fuel. Carbon dioxide is
also the matter being discussed for the future regulation. UE engine
adapts to IMO Tier II with engine parameter optimization such as
Miller cycle, fuel injection rate, optimization of fuel spray and swirl
fl ow in combustion chamber in order to prevent large increase of
carbon oxide. For IMO Tier III regulation, aftertreatment of emission
is under consideration. Combination of exhaust gas re-circulation
and water injection could be possible to reduce nitrogen oxides.
However, this combination possibly brings some carbon dioxide
increase and reliability degradation caused by sulfuric acid. For
sulfur oxides, reduction of sulfur content in fuel might be well
received and suitable for after treatment and EGR system because of
low sulfuric oxides. In future, demand for carbon dioxide reduction
will probably be strengthened. Several measures are under
investigation such as waste heat recovery system, hybrid turbocharger
and so on. It is assumed that this approach would be signifi cant in
conjunction with shipping mode optimization.
Two-stroke engine emission reduction
technology: state-of-the-art
M. F. Pedersen, A. Andreasen, S. Mayer, MAN Diesel
& Turbo SE , Denmark
Future emission regulation requires drastic reductions of harmful
regulated pollutants from large diesel engines. For marine diesel
engines, especially the recently adopted amendments to MARPOL
Annex VI, contains signifi cantly tightened regulations in terms of
emission control for both existing and new engines. Engine-out
emissions can be controlled either by primary or secondary methods.
Primary methods focus on the process on emission formation and
involve e.g. adjustment of the engine injection equipment, injection
and exhaust valve timing, as well as technologies such e.g. Water-In-
Fuel emulsion (WIF) and exhaust gas recirculation (EGR). Secondary
methods focus on exhaust gas after-treatment and involve for
instance NOx reduction using selective catalytic reduction (SCR)
and scrubber technology for washing out sulfur species as well as
particulate matter. This paper will focus on primary methods. The
regulation, as well as an increasing demand from various owners,
operators, ports and other concerned task holders, has led to MAN
Diesel using part of its R&D resources in developing retrofi t measures
for existing engines. The retrofi ts are aimed at reducing NOx, but
will also be benefi cial for other emission and operation aspects.
Recent results on this work will be presented in the paper. Water in
fuel emulsion (WIF) is an existing wellproven technology for large
two-stroke engines, especially for land based stationary diesel power
plants. Recently WIF has been further investigated on the 4T50ME-X
test engine in Copenhagen. Both the NOx reduction potential as
well as the effect on other emissions is investigated. In this paper
water contents up to 90 % vol. added water have been achieved and
a NOx reduction approaching 60% has been obtained. While the
emission of unburned hydrocarbons (HC) increase somewhat it is
shown that WIF is very effective in reducing the emission of CO.
Results from investigations on exhaust gas recirculation (EGR) will