The 2012 Turbo Symposium took place in Houston in September with attendance up slightly on last year, according to Dr. Dara Childs, Director of Texas A& M’s Turbomachinery Laboratory which organizes the event. Consisting of technical sessions, a large exhibit hall and short courses, it attracts the main players in the oil & gas field each year.
Richard Dennis, Turbine Technology Manager for the U.S. Department of Energy’s National Energy Technology Lab (NETL) provided a keynote encompassing hydrogen turbines, supercritical CO2 (S-SCO2), gas-fired generation opportunities and Integrated Gasification and Combined Cycle (IGCC).
He said that NETL are working with GE and Siemens on advanced H2 turbines which can tie into IGCC. Coal gasification provides a hydrogen fuel which can be combusted with air. In a combined cycle setting, this approach can capture 90% of the carbon. Dennis pointed to the Summit IGCC project in Texas as an ongoing test project for this technology.
Current development work involved the transition to hydrogen turbines operating at 2640° F. If that goal can be attained, the efficiency leap could be as much as 14%. But plenty of challenges remain. Flashback, for example, is a significant issue to overcome. Due to the dynamics and properties of H2, the fuel is low in density, and therefore difficult to inject. This means a larger amount of piping to maintain the same speed, as well as broader flammability limits so you get flashback outside the combustor.
“The laminar flame speed is 10X faster than natural gas,” said Dennis. “It also diffuses 3X faster than natural gas.”
GE’s small-scale machine has been operating for 100 hours with 90% H2 fuel, and 20 hours at 100% H2. During that time, it has successfully maintained NOX levels below 3 ppm.
The event progressed with several informative presentations. Klaus Brun, Machinery Program Director at SWRI briefed the gathering on solid particle surface impact behavior in turbomachines as way to assess blade erosion and fouling.
This is a complex area as the flow field is difficult to predict, and the particles can rotate and be of an uneven nature. Thus damage assessment must take into account multiple parameters and requires a detailed look.
“Solid particle admission is one of the big causes of failure,” said Brun. “We can use impact analysis to optimize flow path design.”
He advocated the use of harder coatings in high erosion areas, improved filtering techniques to target the particles which cause the most damage and better maintenance strategies.