Characteristic Analysis Of A Fuel Cell And Gas Turbine Hybrid System Utilizing Biomass Syngas

Biomass gasification technology is an advanced method to utilize biomass which can invert solid biomass to combustible gas. High temperature fuel cell is one of the most effective devices for the electrochemical conversion of chemical energy of hydrocarbon fuel into electricity. In practice, high temperatue fuel cell'efficiency can be further increased by integrating it with a gas turbine (GT) to form a hybrid system. Fuel cell and gas turbine hybrid system is quite suitable for biomass that is small-scale and scattered; the economy of using biomass gas can be greatly enhanced.The objective of this paper is to analyze the characteristics of fuel cell and gas turbine hybrid system utilizing biomass syngas. The work was mainly focused on the following aspects:(1) Various present stage methods of biomass gasification and purification were analyzed to select the optimal plan for the gasification and purification. The components and heat value characteristics of the biomass syngas were summerized. Comparisons are made between the conventional power systems and high temperature fuel cell to use biomass syngas. The results show that high temperature fuel cell is more competitive. The generating efficiency of high temperature fuel cell could be further improved by combination with the gas turbine.(2) Based on the simulation platform of MATLAB/Simulink, a model for fuel cell and gas turbine hybrid system utilizing biomass syngas was established. To build a mathematical model for molten carbonate fuel cell, the mass, momentum, energy, specifies mass balance equations and thermodynamic properties have been included, at the same time, the different polarization loss, heat conversation ways and detailed gas characteristics have been considered in the modeling. The gas turbine models are developed based on the component performance maps. Other components models are developed by using conservation of mass, energy and state of ideal gas equations. Based on the components models, steady state and dynamic model of fuel cell and gas turbine hybrid system utilizing biomass syngas are established.(3) Steady-state characteristics of the hybrid system were analyzed by the simulation model under off-desgin situations including varitions of pressure ratio, temperature, components and the steam to carbon ratio. The dynamic characteristics were also discussed under situations of step changes of the biogas and load. The influence of the key parameters on the hybrid system was detailed considered. This work can become a reference to the system control and management for the experimental system.(4) The fuel cell and gas turbine hybid system utilizing biomass syngas experiment plant is developed. Key components such as catalytic combustor, heat exchangers have been designed. Experimental data during system startup, shutdown, and stable operating process are acquired and analysized in detail. This work demonstrated the concept of integrating a high temperature fuel cell stack with a gas turbine, and provided the necessary theoretical guide and experimental experience. But because of the bottleneck of fuel cell fabricating technology development, parameters of fuel cells used in this paper is not well matched with gas turbine's, which leads to low system efficiency, thus the advantage of hybrid system is not well represented. Much additional development is no doubtly required to develop a stable, high efficiency hybrid system.