Under funding from DOE Award DE-FE0027895, MiTi® is currently conducting Phase II of a program for the design, integration, and testing of four ultrahigh-speed, high-temperature oil-free anode recycle blower (ARCB) test units in a 200 kWe SOFC prototype power plant. In Phase I we demonstrated that the initial prototype ARCB had achieved a TRL-6 and identified areas to reduce cost and improve its design for mass production, and commercialization. The Phase II prototype has been subjected to full operation checkout testing and is expected to achieve TRL-7 after testing in FuelCell Energy Inc.’s 200 kW solid oxide fuel cell (SOFC) power system (funded by the SECA/SOFC program under Award DE-FE0026199).
As a result of its oil-free high temperature capability (up to 180OC) and since it is hermetically sealed, MiTi’s ARCB offers a maintenance-free, high-reliability, long life option to directly recycle the SOFC anode off-gas, which in turn allows the fuel reforming process to take advantage of the water already present in the stream and eliminates the need for an external water supply. The ARCB also eliminates or reduces the need for other hardware, like ejectors, along with their associated performance penalties, increasing plant efficiency and reducing BOP costs. Additionally, its robust compliant foil bearing (CFB) based design gives the ARCB a long and maintenance-free life.
During the past year, MiTi designed and commissioned a “test loop” facility for testing ARCBs in realistic operating conditions that are representative of the environment expected in an actual SOFC power plant. To date, the test loop has successfully reached 180 hours of ARCB testing in high temperature environments (100OC, 130OC, and up to 180OC), spanning starts/stops, and a broad sampling of the full SOFC design range of flow and pressure conditions.
MiTi is partnering with Velo3D to incorporate additive manufacturing (3D printing) methods and techniques into the development of high-speed turbomachinery. Additive manufacturing can reduce cost and time to produce turbomachinery parts and can allow for geometries that are impractical or even impossible to manufacture using conventional machining.
MiTi’s first project with Velo3D was the development of a compressor housing for supercritical CO2 concentrated solar power plants. The innovative housing that MiTi engineers designed, using MiTi’s proprietary oil-free bearing technology, has a unique and complex internal structure and must operate under extremes of temperature and pressure, making it difficult, expensive, and time-consuming to manufacture using conventional casting and machining. Velo3D was able to print the housing in 3.5 days rather than 20 weeks and for a fifth the cost.
Encouraged by the success of the compressor housing, MiTi and Velo3D have printed impellers for high and ultra-high temperature anode gas recycle blowers (ARCB). The complex geometry of impellers presents difficulty in manufacturing by conventional machining. MiTi is currently characterizing the material properties and characteristics of the first round of Velo3D-printed impellers with the view toward improving aerodynamic efficiency with designs that have been unaffordable or impossible until now.