The ships themselves are impressively large. The largest LNG carriers capable of docking at the Ras Laffan terminal in Qatar are Q-Max size.
A typical Q-Max gas tanker is 345m (1,132ft) long, 53.8m (177ft) wide, and 34.7m (114ft) in height, with a draught of 12 m (39ft). The Q-Max has a cargo capacity of 266,000m3 (9.4m cuft), equal to 161,994,000m3 of natural gas. According to estimates, this amount of fuel can light up 70,000 U.S. homes for one year, according to Maritime Connector.com
A single, slightly smaller Panamax sized tanker will need between 170 and 180,000m3 of foam. This is equivalent to 1.5kT tonne of polyurethane, Jang said. ”It’s not easy is like a normal rigid foam,” said SM Yang, CEO of Dongsung FineTec.
The foams are blown with HFC 245fa, “it’s very expensive,” Yang added. “HCFC141b cannot be used and, it’s not yet possible to get the insulation required with pentane,” said Jang. “We’ve been studying various kinds of blowing agent systems including HFC 245fa and LBA and other new agents including pentane,” said Jang.
The foam is characterised by very small cells, Jang said. “This is not simple insulation foam.” The foam also contains uni-directional glass fibre reinforcement along the lengths of the blocks.
“We control the number of layers of glass fibre, depending on the thickness of the block,” said Jang. The glass fibre constrains the rise of the foam and helps keep the sole small, he said.
PU Composite blocks
“About 10 weight percent of each block is glass fibre,” Jang said. This makes the block structurally quite tough.
The blocks are made by pouring the reacting liquid polyol and isocyanate mixture into the continuous glass fibre rovings, Jang said. The number of layers of glass fibre increases with block thickness Jang said “we have to test them in the X, Y, Z directions in strength and compression tests.” The glass fibres help hold the blocks in shape under pressure.
It took a long time to get the formulations and block structures approved. All of the chemicals used to make the polyurethane blocks have to be approved by the engineering companies which build the ships, said Jang. “We contacted many companies, gathered samples and then we started the approval process,” Jang said.
The shipbuilders guarantee each ship for a minimum of 30 years.
As part of the design process, Dongsung Finetec has carried out its own structural analysis of the lined tanks and the forces that act on them. The tanks are a “big space on the boat filled with liquid at -163°C. The ships roll and pitch, so the liner and insulation have to be able to withstand very big weight and pressure to withstand. The foams need to have some resilience.”
In addition to mechanical engineering skills Dongsung Finetec needs to understand heat transfer.
This is why the formulation and foam formulation process is strict, Yang explained.
Tough specifications
There are three South Korean shipbuilders, Hyundai Heavy Industry, Samsung Heavy Industry and, Daewoo Heavy Industry. These have 80% of the world LNG tanker market.
Yang, said his firm has 60% of that market and supplies systems to the other Korean foam maker active in the sector. Dongsung’s expertise includes devising the formulation by Heyon sung Kim, who was awarded by the Korean Polyurethane Society for that work in November 2014.
Yang sees little interest in trying to repeat this business in Japan where the remainder of the LNG tankers are built, because the technical specifications are considerably different.
In addition, Yang explains that, due to the high amount of capital needed to build ships it is very difficult to expand production in different countries. This ties Korean producers to Korea. Capital is not the only hurdle, Yang explained.
“In 2011 there were 40 vessels ordered,” said Yang. “In 2012 the number was about 27, but the ships can be delivered up to three years after the order,” Yang said. This enables ship builders to smooth out peaks and troughs in demand. “In 2013 the number was almost 40 again,” Yang explained. “It’s likely that between 35 and 40 ships will be ordered every year until 2020,” Yang said, this came from Clarkson the shipping data firm.
If there are 35 to 40 ships built per year in Korea this will consume all of the company’s capacity.
“We carefully need to think about more capacity,” said Yang. “China and India are also very keen to have their own technology in their own ships,” Yang said. This could be a competitive pressure, he suggested.
Big warranties
But it seems to be some way off. This will be more than five years, he said. The key though is that companies must be to guarantee ships for 30 years and that’s not easy, he said.
Where can Dongsung go for growth then? It already installs the polyurethanes and builds tanks inside the tankers, (see box).
Yang said Jang’s team is working on stepwise improvements in formulations. “Our team has already improved the technology to take it to another level we call it C1, C2, C3, C4,” said Jang.
When all is said and done, “Better polyurethane means a better price and more orders,” Yang said.
Jang added “We already have approval for the second step and also we are studying thermal improvements.”
Yang said: “As you can imagine every year 30 to 40 ships year will be built, smaller and less efficient not so well insulated ships will tend to be scrapped first.”
Growth opportunities may come from the changing shape of LNG carriers. While there are economies in moving large volumes of LNG, there could soon be a need for smaller distribution vessels.
Tankers keep on growing
Yang said, “In the future, we predict that very large carriers will transport between continents and this will then be trans-shipped into smaller tankers for local distribution.”
In Europe and America there are navigable rivers such the Rhine, Danube and Mississippi and there are canals that could be used to move LNG into the hearts of the continents, avoiding environmental concerns but putting fuel onto roads or rails. There could be opportunities here, suggested Jang.
Jang added: “In the future if LNG or LPG becomes used as a transportation fuel, somebody will have to make the tanks at the fuel stations and insulate them to,” said Yang.
“Ship owners will have to change some heavy fuel, because of changing regulations,” said Jang, he added “LNG is really clean energy with fewer particles than is the case with diesel engines used for ships,” Jang said
There’s already some progress on this in America, said Yang.
“In future trends, we will see tankers moving from oil to natural gas,” said Yang.
Closer to the customer, some countries such as the US are discussing whether coastal shipping should be built within the US. If that happens, we may need to decide to build a small factory, but that’s just a discussion at the moment.
Size of the LNG market.
According to BG group, LNG deliveries in 2013 were estimated at 240m tonne, effectively flat year on year for the second year in succession.
Asian and Latin American LNG markets continued to grow with China, South Korea and Mexico saw the largest rise in demand growth. China, the world’s fastest growing energy market, bought three new terminals online in 2013.
New terminals were built in Israel, Singapore and Malaysia. LNG imports to Thailand and Indonesia also increased in 2013, said BG Group.
Japan, which has seen a large increase in imports following its decision to close nuclear power plants, is close to its physical storage and gas to electricity generation capacity, BG Group said.
Asia is an attractive home for LNG and there was 22.7m T of long haul trade from the Atlantic to the Pacific basin in 2013, BG Group said in its global trade summary for 2013.
Constructing the insulation inside the tank.
Each of the LNG tanks is initially lined in plywood. This is fastened to the superstructure of the ship.
Next to the plywood a thick 30mm layer of rigid polyurethane foam is attached in blocks. Several of the blocks will be separated by glass wall to allow for thermal expansion and contraction.
Above this layer, there is a three layer flexible membrane which acts as a secondary barrier if the metal liner fails.
Above this membrane sits a further 10cm of polyurethane block. This is secured through the membrane mechanically. Above this layer of polyurethane sits a corrugated metal membrane.
This membrane has a complicated waffle-like structure with vertical ridges at right angles to each other. This design means that all of the thermal expansion and contraction takes place in the vertical plane into the tank. Consequently there is no movement in walls of the tank where the metal membrane is attached to the polyurethane foam blocks beneath.
