Soaring demand for methanol underpins the MR2 product tanker Mari Couva
Tanker Shipping & Trade attended the naming ceremonies of 49,000 dwt Mari Couva and Mari Kokako at Korea’s Hyundai Mipo Dockyard (HMD). These two ships are the first in a series of four being built at HMD and will be operated by Waterfront shipping, a subsidiary of Methanex. The vessels are on time charter to Methanex under the direction of Waterfront Shipping.
The vessels are owned by single purpose companies managed by Swedish shipowner and investment house Marinvest, the chairman and chief executive of which, Patrik Mossberg, described the vessels as: “Second generation, safe and future proof methanol dual-fuel vessels.”
Mari Couva key dates:
The vessels have been built specifically to carry Methanex methanol cargoes, but will trade with other petroleum cargoes on the back-haul voyages. The cargo tanks are zinc-coated which allows for carriage of Methanol, as zinc is able to withstand Methanol for prolonged periods.
Methanol is produced from natural gas, coal, or bio products. Around 45% of global methanol production in used as an energy source and the remainder as a chemical feedstock. In 2018, approximately 78M tonnes of methanol was produced globally, with 36.7M tonnes produced in China, which is also the biggest consumer, absorbing 54% of demand. Fortunately for shipping, the demand for methanol in the rest of the world is often far away from production.
The main consumers are large chemical producers and energy companies, including BASF, Dow, and Sinopec and demand is growing. The demand growth for methanol is equivalent to two large methanol plants a year. It is against this background that Waterfront Shipping undertook to order four more product/methanol carriers to add to the seven methanol-burning ships delivered in 2016.
The carriage of methanol is straightforward and the cargo arrangements are comparable to other product tankers of the same size. Nine cargo tanks are laid out in pairs along a longitudinal corrugated separating bulkhead. The vessel does not burn methanol directly from the designated cargo tanks but from the slop tanks.
Each cargo tank is served by a single 600m3/hour Framo stainless steel hydraulic deep-well pump with built in stripping. Framo pumps were also fitted on the first-generation vessels. The slop tanks, which can also act as the methanol fuel storage tanks, also have Framo stainless steel hydraulic deep-well pumps with a 300m3/hour capacity. Each tank is served by its own pipework, pressure/vacuum valves (Pres-vac) and cargo butterfly valves (Keystone). The valves are operated by an Emerson remote control system.
Therefore, Mari Couva and sister-ship Mari Kokako have 18 cargo segregations each, although this is unlikely to be required. Each zinc-coated tank is equipped with Polarmarine tank washing machines (two fixed per cargo tank, one per each slop tank, one in a residual tank) with inspection hatches if a surveyor needs to enter the cargo tanks. However, Waterfront Shipping states that its cargo counterparts are in partnership with a non-tank entry tank washing inspection regime. Following consultation with L&I on the first-generation methanol carriers, a tank washing analysis using a spectrometer is the primary cargo tank washing inspection system.
Krohne Skarpenord has supplied the tank radar for assessing ullage in the tanks and has also provided the gauges. An Alfa Laval Pureballast 3.1 ballast water treatment system (BWTS) is the chosen BWTS system and is installed in a separate, dedicated deck house. This system is USCG type-approved. Once again, high-quality Framo pumps are employed in the ballast water system.
Methanol used as fuel is loaded in one of the slop tanks and in service the fuel is pumped from the slop tank to a service tank situated on the deck, located next to the cargo control room. Within the engineroom, all the methanol fuel pipework is double walled and the outer pipe is ventilated 30 cycles per hr. The methanol piping is colour-coded bright yellow to differentiate it from MGO or other LSFO.
According to the Methanol Institute, which promotes the use of methanol as a fuel, there is no difficulty in procuring methanol for bunkering. The Methanol Institute’s chief operating officer Chris Chatterton told Tanker Shipping & Trade: “We have 97 ports confirmed where methanol is either available directly in the port or within close proximity through chemical distributors/suppliers.”
Waterfront’s president Paul Hexter said that although the vessels burn methanol: “They are completely flexible and give the benefit of running on the most cost-effective fuel. “ He added: “Over the last 10 years, methanol has been cost competitive with other low-sulfur marine fuels, such as MGO, on an energy-equivalent basis.”
The control system for the methanol fuel supply is a development of engine designer MAN Energy Solutions, the engine builder Hyundai Heavy Industries and Alfa Laval. Methanol has been used in internal combustion engines for many years, famously in race cars, where the low flash point and miscibility in water are advantageous.
In late 2013, Alfa Laval was selected by MAN Energy Systems to deliver Low-Flashpoint Supply Systems (LFSS) for the first-generation methanol-fuelled tankers. A key feature is the electronic control available in the MAN Energy Solutions ME series engine.
Fuel injection is via a Fuel Booster Injection Valve (FBIV) which is designed as a unit injector, combining a hydraulically actuated plunger pump with a spring-held injection needle valve that opens at a given fuel pressure. The pump of the FBIV uses hydraulic pressure to increase the methanol pressure to the required injection pressure. A suction valve allows filling of the pump chamber after each stroke. The methanol supply pressure has been chosen to be within 8 to 10 bar.
Two FBIV per cylinder head inject the methanol, which has a lower calorific value than HFO, MGO or MDO. Methanol is also ‘dry’ and the injectors require high pressure lubrication. This also acts as a seal in the injector and eliminates methanol leakage to the hydraulic oil. With methanol there is no methane slip, as is experienced with LNG.
Each cylinder head has two conventional fuel valves and two methanol fuel booster injector valves. The conventional fuel valves also act as a pilot to ignite the methanol. The reason for the pilot is to ensure controlled combustion. Methanol itself would ignite under compression anyway, but the combustion may not be as controlled as it is with a pilot. Methanol combustion itself is immediate and complete.
Should any irregularities develop in operation, such as high temperature fluctuations, pressure differences, or leakage, the dual fuel technology kicks in and seamlessly shuts down the methanol supply, switching to 100% conventional fuel, or ‘primary fuel.’ Should this occur, the methanol lines are then purged with nitrogen supplied by the Air Products nitrogen plant. In fact, the ship can run on either fuel one after the other, effectively doubling the trading range.
New design features
The Hyundai Heavy Industries-built MAN B&W 6G50ME-C9.5-LGIM main engine is rated at 7,180 kW at its MCR and features some new design features. Some of the pipework has been eliminated and replaced by pathways in the engine block. It gives the engine block a remarkably ‘clean’ appearance and as one engineer onboard ship noted, it will reduce the unnecessary repairs caused by human error when someone’s boot accidently crushes an oil pipe. The generators were designed by Hyundai Heavy Industries’ own engine company HiMSEN, backed up with an emergency generator (an STX-Cummins unit). The propeller was also cast and machined at Hyundai Heavy Industries with the stern tube seal supplied by Wärtsilä.
Methanol produces no sulphur emissions and in tests, the main source of such emissions has been from the pilot fuel. However, to meet Tier III NOx requirements the ME-LGIM engines for Mari Couva and Mari Kokako were ordered with SCRs.
“Methanol also has the ability to achieve Tier III without exhaust treatment. In theory, we can avoid the cost of an SCR and the cost of the running the SCR,” said Mr Hexter.
The SCR will be redundant (unless not running on methanol) following the installation of a recently developed water injection system, which takes advantage of methanol’s mixing ability with water.
Water injection is a well-known concept. It lowers the combustion temperature, which reduces the production of NOx but requires a pilot fuel to start the combustion process. In tests, up to 40% of water in volume was added, which reduced the NOx emissions but also increased fuel consumption slightly. The burn duration also alters depending on the load. This requires careful monitoring, which could not be achieved without the electronic control systems of the ME engine.
The pilot fuel and methanol are already present in this latest generation methanol carrier; the next stage is to fit the water injection system. A centrifugal pump is to be installed in the methanol control room on the deck. Clean water from the ship’s Alfa Laval freshwater generator will mix up to 40% water by volume, depending on engine load, with methanol and the resulting charge lowers the NOx emissions well below Tier III standards.
The system will require energy for the centrifugal pump and place extra demand on the freshwater generator, but these costs are minimal compared to the cost of running an SCR. If or when there is a third-generation Marinvest methanol carrier series, the design will almost certainly incorporate a variation of this water injection system, following the experience gained on Mari Couva.
Mari Couva is equipped with well-known and proven Rolls-Royce rotary vane steering gear. An impressive amount of space was freed up in the aft machinery space compared to a ram-type steering assembly, which could be optimised in further iterations of the vessels. Rolls-Royce also supplied the winches and windlasses on the deck.
Moving upwards through the vessel to the engine control room, integration of the engine management and ship control systems is supplied by Kongsberg and accessed via touchscreens which are duplicated on the bridge and the chief engineer’s cabin.
The ship is equipped with Inmarsat’s FleetXpress VSAT communications system for its satellite communication. The setup also allows for ashore or remote access to the ship, whereby live data is available, supporting remote trouble shooting if required.
One interesting aspect of the new ships is that the vessels have separate ship managers. Fleet Management is supplying the crew for Mari Couva and Thome Shipmanagement for Mari Kokako. The reason given is that having separate ship management companies supplying the crew gives the owners unique data on key performance indicators.
The crew quarters are cooled by a Hi Air Korea air conditioning system and the crew can keep themselves in condition in a separate gym. There is also a nicely appointed owner’s cabin and the galley is outfitted with Loipart/Electrolux units. Instead of raised floors, the conduits and pipework are housed in the deck space above the cabins below the bridge and gather into a central shaft that travels vertically to the bridge.
The bridge is fully equipped with Furuno equipment throughout, except for the Tokyo Keiki auto pilot/gyro compass and the NAPA loading computer. This system also monitors the ullage in the on-deck holding tank for the methanol fuel system.
The deck equipment is of a high standard, including Rolls-Royce mooring and anchor-handling equipment. Hose handling/provisions crane were supplied by Oriental. Jotun supplied the tank and hull coatings, while KCC, whose paint factory is next door to Hyundai Mipo (said to be the largest paint factory in the world), supplied the coatings in the machinery space, and deck house.