Optimized IGCC Cycles for Future Applications

Use of gasification based on dirty fuels in markets other than syngas production for downstream chemical processes is emerging due to market changes associated with improved gas turbines, deregulation of electric power generation, as well as more and more stringent environmental regulations. Especially for the increasing quantities of opportunity fuels such as refinery residues, biomass and some grades of coal, integrated gasification combined cycle (IGCC) technology is best suited to producing affordable and clean power. In this contribution, all relevant aspects are discussed in the context of growing operational experience gained e.g. in the major European IGCC power stations: the Demkolec plant in Buggenum, Netherlands, is in the third year of successful commercial operation on syngas. The Elcogas plant in Puertollano, Spain, and the ISAB plant in Priolo, Italy, are also in syngas operation. Future IGCC plant designs and their significance for effectiveness, environmental and operational behavior and conservation of resources as well are the main focus of this paper. The results of cycle calculations are included to illustrate the above. Optimizing the bottoming cycle, for instance, is an effective means to improve IGCC concepts further. Polygeneration, i.e. simultaneously producing electrical power, district and process heat as well as chemicals such as hydrogen, ammonia, methanol and fertilizers, is another important process described here to meet today's requirements on modern power plant technologies. Moreover, topping an IGCC in the long term with solid oxide fuel cell equipment will achieve the highest overall efficiency of plants based on low-grade fossil fuels. IGCC stations must, of course, compete with all other power plant configurations. In particular, this includes supercritical pulverized-coal-fired steam power plants and the other so-called clean coal technologies, e.g. pressurized fluidized bed combustion. A comparison has been elaborated showing the outstanding performance of advanced IGCC concepts. Which position IGCC plants can ultimately achieve in the future liberalized electricity market, strongly depends on the extent to which the requirements of power producers in terms of capital investment, electricity generation costs, availability, relevant environmental regulations, site-specific conditions, field of application and disposal considerations can be met.