Sapphire Technologies and TB Global Technologies Ltd. have jointly developed a turboexpander generator that harnesses waste energy in city gas transportation routes. Two FreeSpin In-line Turboexpanders (FIT) were successfully commissioned at the Toho Gasin’s Yokkaichi liquefied natural gas (LNG) terminal in Japan. The units, working in continuous operation since commissioning this spring, produce over 400 kW of power and up to 3.5 gigawatt-hours of electricity each year.
In the supply process of city gas to the terminal, the natural gas is transported at high pressure and the pressure is reduced using a governor (pressure regulator) according to the usage at the customer’s site. Gas expansion energy is generated when the pressure is reduced, but to utilize this energy, it has been necessary to install turbines, generators, and other incidental equipment, which has hindered the dissemination of such technology. FIT recovers the energy lost in pressure letdown and liquefaction processes. The system’s turboexpander-generator extracts kinetic energy from the pressure reduction at the various stages of gas processing and distribution and allows for the generation of electricity with no added pollution, the company said.
In addition to natural gas and hydrogen, FIT is compatible with compressed air, carbon dioxide, and other process gas applications. The turboexpander-generator assembly contains a high-performance, high-speed permanent magnet generator with an integrated radial in-flow expansion turbine and low loss active magnetic bearings. FIT’s “flow-through” design directs the expanded fluid directly over the generator, providing integrated cooling and eliminating the need for auxiliary cooling equipment. Sapphire Technologies’ proprietary power electronics unit combines a variable speed drive and a magnetic bearing controller into a single cabinet.
“The successful commissioning of both Free Spin In-line Turboexpanders is an important milestone,” said Freddie Sarhan, CEO at Sapphire Technologies. “We are excited to bring new and cost-effective solutions to the Japanese market to generate clean electricity and significantly reduce CO2 emissions during this critical time.”