Using a Plasma Fuel Reformer to Extend Combustion Lean Limits

There is a clear and unmet need for technologies to improve power generation flexibility to enable cost effective and reliable high renewable energy fractions in modern grids. Specifically, gas turbine generator turndown ratio may be improved by extending combustion lean flammability limits. This project will deliver a prototype plasma reformer system integrated with gas turbine combustors to allow turndown ratios of 5:1 to 10:1. The work funded in Phase I of this program showed for the first time that a plasma assisted reformer using a non-thermal plasma (Plasmatron) can be operated successfully under pressure at particle number densities typical of those in industrial turbine combustors. A device was designed and successfully tested to demonstrate hydrogen yields that approached chemical equilibrium values. Modelling of the Plasmatron indicated that it may be possible to further improve the performance of the device, to be carried out in Phase II. Furthermore, chemical kinetics calculations showed that significant improvements in gas turbine turndown can be achieved by using a Plasmatron reforming only part of the fuel flow of a gas turbine. For a 5MWe turbine, this results in Plasmatron flowrates similar to the ones demonstrated in this program. No scale up would be needed. In Phase II, we are planning to integrate the Plasmatron with a gas turbine combustor, so that it can seamlessly be installed in existing power plants as a retrofit. For that purpose, we will first further optimize plasmatron design through simulation and experimental testing. Subsequently, we will simulate its integration with a gas turbine combustor fuel nozzle and test it in a flow bench. We also investigated the business case of the technology. The savings for the turbine operator come from decreasing power generation during times when the price of electricity is below cost. The turbine operators do not turn-off the turbines during those times because of life-time fatigue and restarting issues. By operating at lower power, the costs to the operator are substantially reduced (USD 17Million annual savings for a 580MW plant). It was concluded that with a payback of less than a year and several billion dollars in annual savings for the US Combined cycle market, the technology looks very promising from a commercialization perspective. For Phase II, we have demonstrated interest from Solar Turbines, a division of Caterpillar to work with us on integrating the Plasmatron with their combustors and potentially testing it on their rigs in Phase IIB (letter of support attached). For Phase III, we would work with a powerplant operator to pilot the technology as a retrofit on one of their plants and explore licensing terms. In summary, we achieved all the goals for the Phase I proposal. Phase II is needed to make the technology ready for testing in a turbine. The economic benefits of the technology are significant and near term. With the help of our industrial partner, Solar Turbines, we are well positioned for commercialization and having an impact.