Recently, the first domestically developed /h LNG deep-cooling unit, independently developed by Shanghai Qiyao Technology Group Co., Ltd. (hereinafter referred to as “Qiyao Technology”), a subsidiary of CSSC 711 Research Institute, successfully completed its Factory Acceptance Test (FAT). During the FAT, the unit successfully passed a 200-hour full-load continuous operation assessment, with all performance indicators meeting design requirements. It completed loading onto the ship on April 1, 2026. This marks a breakthrough in the localization of key equipment for LNG boil-off gas (BOG) treatment on ocean-going vessels in China.
The deep-cooling unit is the core equipment of the liquid cargo system on LNG bunkering and transport vessels. The cold energy it generates is used to deeply cool LNG, which is then sprayed back into the tanks to achieve re-liquefaction of BOG (Boil-Off Gas). This process not only avoids the economic losses and greenhouse effects caused by direct BOG combustion and emission but also stabilizes the temperature and pressure of the cargo tanks within an ideal range, suppressing BOG generation at the source. It offers significant advantages such as stability, high efficiency, safety, reliability, and long-term maintenance-free operation.
For a long time, the key technologies and products for this type of unit were monopolized by a few foreign companies, becoming one of the bottlenecks restricting the independent development of large LNG vessels in China. Following the successful delivery of the first domestic small-scale LNG /transport vessel /h deep-cooling unit in 2024, Qiyao Technology, after two years of continuous research and breakthroughs in multiple core technologies, successfully developed China’s first deep-cooling unit for large ocean-going LNG carriers.
During the two-year development process, a joint research team was formed with participation from Qiyao Technology, Shandong Marine Energy, Jiangnan Shipbuilding, and DNV.
The experienced technical team from the shipowner, Shandong Marine Energy, participated throughout the quality monitoring and test standard formulation for the unit, translating real operational needs from ocean-going voyages into stringent technical specifications.
DNV was involved from the design review stage through to test witnessing, ensuring the unit complied with international regulations and safety standards.
Jiangnan Shipbuilding provided crucial support in system integration and cabin adaptation.
This in-depth collaboration with Shandong Marine Energy, Jiangnan Shipbuilding, and DNV established a complete closed loop of “demand-driven—collaborative development—authoritative certification—onboard verification—commercial application.” This is not only a milestone for Qiyao Technology’s deep-cooling technology but also an important practice of collaborative innovation across the industry chain to promote the localization of high-end equipment. All parties will use this cooperation as a starting point to continue exploring deeper collaboration in the field of green and low-carbon shipping technologies, jointly enhancing the international competitiveness of China’s LNG industry chain.
To ensure the reliability and stability of onboard operation, the project team set test standards far exceeding existing industry norms. The 200-hour continuous full-load operation assessment during this FAT, described as a “devil’s test,” was proposed by the shipowner based on the harsh conditions of real ocean-going routes and was passed in one attempt under the full supervision of DNV surveyors.
During this period, the unit completed full operational mode testing, performance testing, alarm and ESD testing. The successful completion of the 200-hour uninterrupted continuous operation indicates that the unit fully meets the stringent conditions required for long-term, stable, and safe operation on actual vessels, ensuring exceptional stability and reliability throughout its future operational life of up to 20 years.
Currently, the unit has been officially installed on a 175,000 cubic meter large LNG carrier built by Jiangnan Shipbuilding, entering the onboard application phase. The successful delivery of this unit marks a critical step in the localization process of core equipment for large LNG carriers in China, effectively reducing construction costs and maintenance cycles, and enhancing the industry chain’s self-reliance and controllability. Qiyao Technology will continue to deepen its expertise in deep-cooling technology, contributing greater strength to the green and low-carbon transformation of the shipping industry and the localization of high-end equipment.
