Article LNG Fuel Conversion
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TANKEROperator January/February 2012 40 TECHNOLOGY - PROPULSION SYSTEMS T he conversion project was undertaken under the supervision of Hamburg-based class society Germanischer Lloyd (GL). Once converted, the tanker has become a dual-fuel vessel, able to burn fuel oil, or liquefied natural gas (LNG). Ronnie-Torsten Westerman, GL’s business development manager, writing in the class society’s magazine ‘Nonstop’, explained: “The project started with a kick-off meeting of representatives from Wärtsilä, the owner Tarbit Shipping and GL in April 2010.” Manufacturing of various new components began in early 2011. They were then transported to the shipyard in Landskrona, Sweden. “The Bit Viking arrived at the yard on time and the conversion commenced in August,” said Westerman. Upon her arrival, the new equipment necessary for LNG operation was installed in the vessel. GL’s staff played a critical role in this process by monitoring the manufacture and installation of the components, such as piping, valves, safety equipment and LNG tanks and ensuring safe construction, use of suitable materials and application of appropriate welding methods. The two main engines were converted from Wärtsilä VASA type 46 D to type 50 DF. Westerman said: “Virtually everything was replaced except the crankshafts and frames.” The Bit Viking was then taken to Risavika/Stavanger for completion of the pipe installation, the testing and calibration of the newly installed equipment. She was then ready for her first bunkering of LNG. “The first time we prepared for bunkering we had to cool down the LNG storage tanks on the fore deck using liquid nitrogen at –192 deg C”, explained Westerman. She then successfully bunkered LNG, which has a temperature of –162 deg C, for a main engine test run at the pier. By the end of October, the Bit Viking was finally ready for her official sea trials. “She performed as expected and no major discrepancies were noted. GL had two surveyors on board during the sea trial. The technical challenge in steering the conversion process was immense,” said Westerman. Key concerns were the proper interpretation of class rules for safe construction, ensuring that the equipment manufacturers clearly understood the class rules and anticipating how the flag administration (Sweden) would understand and accept the required risk analysis. “Particular focus was on bunkering and how it should be performed, since this is a somewhat critical operation that requires special knowledge and equipment,” Westerman said. Testing the rules The conversion of the Bit Viking also provided a good opportunity to put the GL rules for gas as ship fuel (see box) to the test. Following the successful conversion, Westerman expressed optimism; “The existing rules are sufficient for a conversion such as that of the Bit Viking. However, some modifications will be made in the future as regulations, such as Marpol, are updated to reflect the option of gas as a ship fuel.” First LG-fuelled retrofit resumes service The 24,783 dwt chemical tanker Bit Viking was the world’s first vessel converted to run on LG while in service. After successful sea trials under GL supervision, the vessel has resumed commercial trading. Bit Viking was built at the Edwards Shanghai shipyard in China with double engine rooms, propellers, steering gears, rudders and control systems – a full redundancy package. Having previously been powered by two 6- cylinder in-line Wärtsilä 46 engines running on heavy fuel oil, the conversion has changed these to 6-cylinder in-line Wärtsilä 50DF dual fuel engines, capable of operating on LNG supplied from two 500 cu m LNG storage tanks on the fore deck. The 24,783 dwt chemical tanker is currently on long term charter to Statoil, trading on and around Norway’s west coast, thus qualifying for Norway’s emission tax rebate. Bit Viking fact file General arrangement drawing showing the deck layout.
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Transcript of Article LNG Fuel Conversion
TANKEROperator � January/February 201240
TECHNOLOGY - PROPULSION SYSTEMS
The conversion project wasundertaken under the supervisionof Hamburg-based class societyGermanischer Lloyd (GL). Once
converted, the tanker has become a dual-fuelvessel, able to burn fuel oil, or liquefiednatural gas (LNG).Ronnie-Torsten Westerman, GL’s business
development manager, writing in the classsociety’s magazine ‘Nonstop’, explained:“The project started with a kick-off meeting ofrepresentatives from Wärtsilä, the ownerTarbit Shipping and GL in April 2010.”Manufacturing of various new components
began in early 2011. They were thentransported to the shipyard in Landskrona,Sweden. “The Bit Viking arrived at the yard ontime and the conversion commenced inAugust,” said Westerman. Upon her arrival,the new equipment necessary for LNGoperation was installed in the vessel. GL’s staff played a critical role in this
process by monitoring the manufacture andinstallation of the components, such as piping,valves, safety equipment and LNG tanks andensuring safe construction, use of suitablematerials and application of appropriatewelding methods.
The two main engines were converted fromWärtsilä VASA type 46 D to type 50 DF.Westerman said: “Virtually everything wasreplaced except the crankshafts and frames.” The Bit Viking was then taken to
Risavika/Stavanger for completion of the pipeinstallation, the testing and calibration of thenewly installed equipment. She was thenready for her first bunkering of LNG. “Thefirst time we prepared for bunkering we had tocool down the LNG storage tanks on the foredeck using liquid nitrogen at –192 deg C”,explained Westerman. She then successfully bunkered LNG, which
has a temperature of –162 deg C, for a main
engine test run at the pier. By the end ofOctober, the Bit Viking was finally ready forher official sea trials. “She performed as expected and no major
discrepancies were noted. GL had twosurveyors on board during the sea trial. Thetechnical challenge in steering the conversionprocess was immense,” said Westerman. Key concerns were the proper interpretation
of class rules for safe construction, ensuring thatthe equipment manufacturers clearly understoodthe class rules and anticipating how the flagadministration (Sweden) would understand andaccept the required risk analysis. “Particularfocus was on bunkering and how it should beperformed, since this is a somewhat criticaloperation that requires special knowledge andequipment,” Westerman said.
Testing the rulesThe conversion of the Bit Viking also provideda good opportunity to put the GL rules for gasas ship fuel (see box) to the test. Followingthe successful conversion, Westermanexpressed optimism; “The existing rules aresufficient for a conversion such as that of theBit Viking. However, some modifications willbe made in the future as regulations, such asMarpol, are updated to reflect the option ofgas as a ship fuel.”
First L!G-fuelledretrofit resumesserviceThe 24,783 dwt chemical tanker Bit Viking was the world’s first vessel converted to run on L!G while in service. After successful sea trials under GL supervision,
the vessel has resumed commercial trading.
Bit Viking was built at theEdwards Shanghai shipyard inChina with double enginerooms, propellers, steeringgears, rudders and controlsystems – a full redundancypackage. Having previously been powered by two 6-cylinder in-line Wärtsilä 46 enginesrunning on heavy fuel oil, the conversion
has changed these to 6-cylinder in-lineWärtsilä 50DF dual fuel engines, capableof operating on LNG supplied from two500 cu m LNG storage tanks on the foredeck.The 24,783 dwt chemical tanker is
currently on long term charter to Statoil,trading on and around Norway’s westcoast, thus qualifying for Norway’semission tax rebate.
Bit Viking fact file
General arrangement drawing showing the deck layout.
TECHNOLOGY - PROPULSION SYSTEMS
January/February 2012 � TANKEROperator 41
While the advantages of LNG-fuelled shipengines are well known, there are a fewperformance drawbacks compared to fuel oil.Furthermore, the two 500 cu m capacity LNGtanks and the associated piping and valves addseveral hundred tonnes to the weight of thevessel. On the other hand, the ship enjoysincreased buoyancy and lifting cargo capacity.Westerman said;” You clearly win on theenvironmental side.”An LNG-powered vessel at this
developmental stage is slightly moreexpensive than a conventionally poweredequivalent, which increases capital costs. Yetwith the advent of cash incentives for loweremissions in some Scandinavian countries,notably Norway where the vessel is tradingunder a charter to Statoil, ship operators canalso save money via rebates.Where Scandinavia has taken the lead,
others will follow, GL said. Under rules drawnup by IMO, vessels must cut SOx emissionsfrom 1% currently to 0.1% by January 2015.“Within the short period of operation since
her conversion, the Bit Viking has alreadyachieved considerable benefits for theenvironment,” said Westerman. “Greenhousegases have been reduced by 20% to 25%,NOx gases by 9 %, sulphur output has beencut entirely and particle emissions have beenbrought down by 99%. “An official emissions measurement has
been conducted, but the final results havenot yet been publicised. However, theseestimates should be pretty close to the actual
outcome,” he said.According to GL, Tarbit Shipping is very
pleased with the environmental footprint of itsnewly converted vessel and all projectpartners expressed their appreciation of thegood spirit of co-operation. “We all held firmand stayed focused on the quality and safetyoutcome of the project,” said Westerman. “It
was the final result that counted. This wasvery important, since there is no room forerrors in dealing with an LNG plant!”Bit Viking resumed commercial trading on
25th October 2011. Ever since, she has beenperforming as expected and the crew hassuccessfully refuelled her from the shore,GL said.
GL has prepared guidelines for gas as aship fuel. Developed by the IMO sub-committee on Bulk Liquid andGases (BLG) with GL assistance over the past few years,the interim guidelines are the first step towards theenvisioned general code for gas as a ship fuel, the so-calledIGF Code.This Code is currently under development by the IMO
and is expected to enter into force conjointly with therevision of SOLAS 2014. The GL guidelines will help shipowners and yards
prepare for the introduction of gas as a ship fuel. They provide criteria for the design arrangements and
installation of propulsion and auxiliary machinery poweredby natural gas to ensure a level of integrity, safety,reliability and dependability equivalent to that ofcomparable, state-of-the-art machinery burningconventional fuel oil, GL said.
GL Guidelines for Gasas Ship Fuel
The gas tanks clearly seen on deck.
The vessel has been operating successfully as a gas-powered vesselsince October last year.
TO
