Matthias Flies, Offshore Applications Manager at SAACKE Marine Systems, explains how to ensure safe transport of liquid hydrogen, providing the example of the first worldwide LH2 tanker which relied on his company technology.
The world’s first liquid hydrogen tanker, christened “Suiso Frontier” in Japan in December 2019, will be equipped with technology from the Bremen-based company SAACKE Marine Systems. The hydrogen-compatible Gas Combustion Unit (GCU) and the SSBG burner ensure that the LH2 can be transported by sea as safely as liquid natural gas. Testing and acceptance of the equipment in northern Germany were successful in October 2019. The GCU will be commissioned by SAACKE until the test run in autumn 2020. The ship is operated by the Hydrogen Energy Supply-chain Technology Research Association (HySTRA), a consortium of several companies and organizations founded four years ago under the leadership of Kawasaki Heavy Industries, Ltd.
The aim of the “Suiso Frontier” pilot project is to demonstrate the smooth running of an international hydrogen energy supply chain from production to transport and use. So-called “blue” hydrogen produced and liquefied in Australia, with carbon capturing taking place on site, is to be shipped in large quantities at 1/800 of its original volume to Japan, whose industry is relying heavily on the energy carrier to make itself less dependent on oil and gas. In this context Japan would like to use the Olympic Games 2021 in Tokyo as a stage for the progressive nature of its energy industry: Here, the Olympic Village is to function as a futuristic quarter in which mobility, electricity and hot water production are based exclusively on hydrogen.
Boil-off gases: Maximum safety through 100% free-flow solution
In order to realize this project, the LH2 carrier must be equipped accordingly with regard to important safety aspects. “Liquid hydrogen tankers are designed for gas transport at a temperature of about -250 °C, i.e. close to the evaporation temperature. Despite the insulation of the cargo tanks, which is intended to limit the entry of external heat, small quantities of heat always enter the tanks and lead to slight evaporation of the gases. This so-called boil-off gas is unavoidable, especially during movements on a ship, and must be removed from the tanks in order to prevent an inadmissible pressure increase”, explains Matthias Flies, Offshore Applications Manager at SAACKE Marine Systems, highlighting the importance of gas combustion units on board the ship. For this reason, the GCUs burn the excess boil-off gas, which is harmful to the climate due to its methane components, completely and with maximum availability. In these processes, compressors with a pressure of 5 to 6 bar are conventionally used. However, there is a risk that the compressor will fail and that safety risks may arise due to the increasing pressure in the tank. “This is why we have developed our 100% free-flow solution,” reports Matthias Flies. He continues: “In this process, the boil-off gas is completely combusted without a compressor and at a pressure of 0.15 bar – the gas pressure is thus much lower and the entire system is safer. This advantage was the deciding factor for the HySTRA customer order, because this SAACKE 100 % free-flow solution is technologically unrivalled, especially for large capacity ranges”. Welded connections from the GCU also ensure additional safety during LH2 transport, as they help to reduce possible leakages.
All of the company’s production sites were involved in the manufacture of the Gas Combustion Unit, which was patented by SAACKE in 2002 – from Bremen via Croatia to China. “This is possible because the boil-off gas of the liquid hydrogen tanker is, unlike that of the LNG carrier, completely combusted in the GCU without further utilization in the ship’s engines. Therefore, proximity to the engine is not absolutely necessary,” says Flies. The hydrogen GCU was built according to the regulations and under the supervision of the Japanese classification society ClassNK. The main task here was to prove that the transport of LH2 is just as safe as that of LNG.
Low NOx hydrogen burner thanks to research lead
This system is supplemented by a SAACKE SSBG hydrogen burner. This differs only in nuances from the model used for land-based industry. Expert Matthias Flies explains this as follows: “On the one hand, the combustion system can be flexibly adapted to the conditions on board. On the other hand, SAACKE has been investing in the research and development of processes for hydrogen utilization for decades – even though the energy source has only recently become very present in the public eye”. For this reason, SAACKE can already offer low NOx and 100% hydrogen burners on the market today.
The views presented hereabove are only those of the author and not necessarily those of SAFETY4SEA and are for information sharing and discussion purposes only.
Matthias Flies is Offshore Applications Manager at SAACKE Marine Systems. SAACKE GmbH specializes in thermal processes and plants in the industrial and maritime energy management sector and is one of the world market leaders in this field. Since the patent was granted in 2002, SAACKE has sold over 100 Gas Combustion Units. The medium-sized family business was founded in 1931 and employs a total of around 1,200 people, including a good 450 engineers and technicians. It has production sites in Bremen (Northern Germany), Croatia, China and Argentina as well as a worldwide service and sales network. Headquarters, main production and research and development are located in Bremen.