emissions
››› funnel casings. The systems incorporate a control system, combined wash-water treatment plant and a new range of super duplex stainless steel pumps from Hamworthy’s Singapore factory. Provision is
also made for the future
installation of scrubbers to cut emissions from the main engine, in line with operation in IMO ECAs. DNV approved the first installation, on Linea
Messina, after testing last October; the system was also classed by RINA, the ships being the first of their type to gain the Italian classification society’s Green Plus notation. “We can now comply with the 0.1 per cent sulphur regulation in EU ports while burning residual fuel oil and are also prepared for the 2015 regulation,” says Enrico Allieri, Ignazio Messina’s newbuilding programme technical director. “We will continue to participate in Hamworthy Krystallon’s R&D programme, which will
closely monitor the scrubbers in
operation as a means of continuously improving their characteristics.”
Designed to run cold but operable at temperatures up to 450oC, the Hamworthy Krystallon seawater scrubber can reportedly remove 99 per cent of SOx and 80 per cent of particulates emissions from exhaust gas associated with 3.5 per cent sulphur HFO. Such efficiency complies with the EU in-port and IMO Marpol Annex VI requirements for 0.1 per cent sulphur fuel. Typically fitting around the funnel space, the lightweight, self-supporting scrubber unit additionally serves to reduce exhaust noise. The associated wash-water treatment system is said to meet or exceed the requirements of
IMO MEPC 184(59) and CFR40 when
handling the full scrubber water flow. Designed to remove both solid particulate and liquid hydrocarbon waste products, the wash-water
treatment reduces contamination to levels
measured in ppm; its discharge is monitored for hydrocarbons, turbidity and pH.
All seawater piping is manufactured from glass-reinforced
epoxy to foster Emissions from the Ignazio Messina ships
will be continuously monitored by Martek Marine MariNOx monitoring systems configured to measure NOx, SOx and carbon dioxide in the exhaust gases of the main and genset engines and the auxiliary boiler. The installations are additionally capable of measuring carbon monoxide, oxygen, hydrocarbons and particulate matter. UK-based Martek
Marine’s MariNOx is
claimed to be the world’s first type-approved (Lloyd’s Register) onboard exhaust emissions and engine efficiency monitoring system.
Best to beat SOx: scrubbers and gas engines
A comprehensive study by MAN Diesel & Turbo and Germanischer Lloyd investigated the best choice of sulphur-reducing technology for a two-stroke engine powering a
container ship. Tonnage operating in
emission control areas (ECAs) must run on marine gas oil or better alternatives by 2015 while those outside ECAs must run on low sulphur fuel by 2020. The new IMO rules on SOx emissions call for a sulphur-reducing system to be installed to serve two-stroke main engines if operators wish to avoid running on more expensive low sulphur fuels. MAN Diesel & Turbo offers three solutions for cutting SOx emissions: • an exhaust gas SOx scrubber • an MAN B&W ME-GI engine running on LNG fuel • burn low sulphur fuel.
An engine operating in conjunction with a scrubber makes it possible to continue running on heavy fuel oil and meet the IMO SOx emissions regulations.
Five container ship sizes on three different routes were selected for the study, with ECAs comprising varying percentages of the route. Waste heat recovery was also included as an option to measure its effect on the different solutions.
Route Distance in miles
1 2 3 3
3 5,300
13,300 23,000 23,000
23,000
Ship size TEU
2,500 4,600 8,500
14,000 18,000
100 I Marine Propulsion I February/March 2012
ECA as % of route
65.1 11
6.3 6.3 6.3
When assessing either the scrubber or ME-GI engine solutions,
says MAN Diesel
& Turbo, the benefits of that engine’s use of sulphur-free LNG and the scrubber’s enabling of economical HFO as a fuel should be considered before evaluating the extra financial outlay of: lost earnings due to the space required on board for both solutions; the investment cost; and any operational costs. The results from the study show that the
impact of the loss of cargo space and the installation cost
is minor compared with
the importance of fuel price when using a scrubber or ME-GI engine solution. It was also shown that LNG can be highly competitive as a fuel if priced at reasonable levels, while the percentage of time the ship spends sailing in an ECA is another factor. A ship with a scrubber installed can run on normal HFO in an ECA, while one without a scrubber must burn expensive low sulphur fuel. Thus, the greater the period of time spent in an ECA, the greater the savings. In short, the study concludes, LNG is the best solution when ECA percentages are low – compared with the scrubber – but, when choosing between ME-GI and scrubber solutions, the price difference between HFO and LNG is important. The LNG-HFO price differential does not have to be very large before the ME-GI engine becomes the solution with the shortest payback time. It is also possible to see from a graph what the LNG price needs to be to make the low speed gas engine the preferred choice. When ships with standard diesel engines
are obliged to run on low sulphur fuel outside ECAs (from 2020) the savings that sulphur-
reducing systems will deliver – due to the large price difference between HFO and low sulphur fuel – are potentially enormous, says MAN Diesel & Turbo.
The payback times for scrubber and ME-GI systems bought now will not exceed 72 months, which corresponds to the interval between 2014 and 2020, based on the assumption that a ship ordered now will subsequently be launched in 2014. MP
sealing oil inlet
corrosion
resistance, low flow losses, light weight and easier installation.
cylinder cover
connection to the ventilated pipe system
control oil sealing oil
gas inlet
gas spindle
Gas engines can meet SOx limits (MAN B&W ME-GI gas injection valve shown)
www.mpropulsion.com
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