Catalytic combustion and system performance assessment of MCFC-MGT hybrid system

The catalytic combustor is applied as an off-gas and startup combustor for a molten carbonate fuel cell-micro-gas turbine (MCFC-MGT) hybrid system (HS) so as to utilize the waste energy of fuel cell off-gas. Three types of catalysts are prepared over a cordieritic honeycomb support. One is Pt catalyst which is not cost effective and less high temperature stability. CeZrO2 and LaMnO3 have been selected as an additive for another two Pt catalysts to improve the performance. Tests have been completed in realistic conditions and reaction feed close to the MCFC-MGT hybrid system. Simulations are carried out with a fluid mechanical code that incorporates detailed transport and heat loss mechanisms. The simulation results are compared with the Pt catalyst test results. The agreement confirms the accuracy of simulation. The model can be used to develop an MCFC-MGT hybrid system with an off-the-shelf gas turbine and assess the performances during part-load operation. From the experimental results, the reaction starts at 620 K for 1 vol.% CH4 using Pt catalyst, while the temperature is above 800 K for the addition of additive. For the 50% CH4 conversion, the preheated temperature of the three catalysts is 713 K, 870 K and 950 K respectively. While all of the catalysts exhibit good performance when using the MCFC off-gas as fuel. The results of performance analysis for part-load conditions show that the cell operation temperature and turbine inlet temperature (TIT) should be maintained as close as possible to the design value to prevent the performance degradation.