CIMAC Congress - Schiff & Hafen

CIMAC CONGRESS | BERGEN 2010
reduction rate at each load and the effects of a kind of the reducing
agent, which are ammonia gas and urea water. As the results, it is
confi rmed that the SCR system has suitable NOx reduction
performance at each load. It is also clarifi ed that there is no deference
by the kind of reducing agent in enough high temperature of the
exhaust gas. On the other hand, we have investigated control
methods with the experimental SCR system. In the control system,
the reducing agent is controlled by a calculated exhaust gas fl ow rate
and a measured NOx concentration. It is confi rmed that the control
system has suitable performance in our early tests. Based on the
above test results, we have designed and developed a SCR system for
a marine Diesel generator on a ship. The SCR system is installed to
the ship and examined on board at sea. In the actual ship, there is
not enough wide space for the SCR. Therefore the distance between
the injection nozzle and the catalyst of the SCR system must be
short, though it is needed a long distance for the conversion to
ammonia from urea generally. We developed a special injection
nozzle for the system and achieved suitable NOx reduction
performance. In conclusion, we got a lot of benefi cial results to
apply a SCR system to a middle-speed marine diesel engine. In the
next step, in order to develop a practical SCR system, it is necessary
to develop a simple and low-cost control system and to estimate a
durability performance of catalyst. Also, in order to apply the SCR
system to large two-stroke diesel engine, we need to examine the
SCR system performance in detail, because the engine has too low
temperature of exhaust gas.
Development of a NOx fast sampling
system for marine diesel engines
M. Ioannou, K. Xepapa, T. Stelios, N. Kyrtatos, NTUA,
Greece
Cylinder specifi c NOx measurements for large marine engines can
provide important information for the combustion system that can
be used by the engine design and development engineers. In
addition, signifi cant cost savings can result from reduced test bed
running times which are usually required to characterise the
combustion system. Furthermore, detailed NOx measured data can
be used for the development and calibration of combustion system
simulation models. Emission measurement equipment that allow
cylinder specifi c measurements are currently only available to
automotive industry applications. Due to the size of marine diesel
engines, and more specifi cally the exhaust system, this equipment
needs to be suitably modifi ed in order to be used in large engines.
The work reported here describes the further design and development
of a NOx fast sampling system applicable to marine diesel engines
towards a more reliable and robust system. The most important
considerations when sampling exhaust gases from a marine engine
is the strong possibility of probe’s blockage due to excessive soot
deposition and the mechanical reliability, without compromising
the performance of the measuring system. All these factors were
considered during the design phase and the developed sampling
system satisfi es all requirements successfully. The main design
parameters of the sampling system were fi rst evaluated though
theoretical analysis, followed by fl ow bench investigations, and the
fi nal evaluation of the design was done on the test bed by performing
NOx measurements on a marine diesel research engine. The
emission measurements were supported by detailed measurements
of the engine performance parameters. The fi nal probe design is a
customised sampling system for a fast response chemiluminescence
detector that can measure NOx in the exhaust gases downstream
the exhaust valve of a specifi c cylinder of a marine diesel engine.
The extremely fast response time of the system enables the
characterization of NOx during an engine cycle with a one degree
crank-angle resolution.
46
Ship & Offshore | 2010 | No. 3
Development of sulfur-tolerant SCR type
De-NOx system for marine applications
Y.-M. Lee, S.-K. An, DSME, Korea, K.-H. Kang, Y.-D.
Yoo, IAE, Korea, Ø. Toft, BW Fleet Management AS,
Norway
Nitrogen oxides (NOx) are mainly generated by combustion of
fossil fuels used for marine vessels. Nowadays, a consensus has been
reached internationally to limit emission of air-polluting
compounds. And the NOx emission level requirements of marine
diesel engine are getting more stringent these days. Especially to
meet the Tier III requirement of IMO MPEC 58, external fl ue gas
treatment system may be necessary as the requirements cannot be
met by NOx reduction system in diesel engine boundary. One of the
possible solutions of the NOx reduction could be the Selective
Catalytic Reduction (SCR) type De-NOx system. However, it is well
known that the SCR performance is greatly affected by the fl ue gas
temperature and the existence of sulfur contents and that the
temperature of exhaust gas from the marine diesel engine is relatively
low and sulfur components are detrimental to the catalyst. In marine
diesel oil, some amount of sulfur is contained in most of the cases.
The typical contents of the sulfur in marine fuel oil could be 1.0
4 ~ .5% range. It is believed that the allowable sulfur level contained in
fuel oil will be gradually reduced. Nevertheless, the complete
removal of the sulfur in fuel oil is impractical due to high
desulfurization cost in the process of fuel oil production. With the
reason, the De-NOx system which can be operated in the existence
of some range of sulfur, typically 1% in fuel oil, might be practically
implemented in the marine diesel engine in the near future. Daewoo
Shipbuilding and Marine Engineering Co., Ltd. (DSME) and BW
Group are developing “Sulfurtolerant SCR type De-NOx system for
Marine Applications”. We have evaluated the durability and
optimum conditions for NOx reduction performance using selected
commercial catalysts and have developed SCR catalyst suitable for
low temperature and existence of SOx contents with a manufacturer
specialized in the SCR catalyst. The infl uences of the SOx contents
and dust for the developed SCR have been compared by extensive
experiments. For the verifi cation of the developed SCR, bench scale
test facility has been utilized. With the facility, various performance
comparisons of SOx and dust have been achieved. The test has been
carried with the collaboration of Institute of Advanced Engineering
(IAE). In addition to the bench scale test, we have been selected
optimum combination of catalyst and SCR operational variables
with the aid of computational fl uid dynamics (CFD). Through the
studies, we expect sulfur-tolerant SCR element and practical De-
NOx system for marine applications would be developed. Based on
the results obtained from the test and CFD analysis, detailed
engineering design and actual onboard tests will be carried out for
targeted vessel. We expect the developed De-NOx system would
contribute to the emission reduction in the marine industry.
10:30 June 15th Room Troldtog
(6–3) Product Development, Component
& Maintenance Technology –
Gas Engines – Technology, Fuels & Emissions
Methane slip reduction in Wärtsilä lean
burn gas engines
A. Järvi, Wärtsilä, Finland
Global warming set reduction needs for all greenhouse gases. Lean
burn gas engines are having superior effi ciency and thanks to lowcarbon
fuel, CO 2 emissions are low compared to diesel engines and
gas turbines. Though the main emissions (CO 2 and NOx) are