Efficiency of a combined gas-steam process

Effect of supplementary firing options on cycle performance and CO2emissions of an IGCC power generation system

“…The enthalpy values for the steam cycle at each state are within the operating range when compared with an existing power plant [22]. The results of the current study confirm the findings of these two studies: (i) [13] and (ii) [14], by showing that lower efficiency and specific net work output are achieved when reheating (supplementary firing) of the gas turbine exhaust is carried out as shown in Figure 1 [28]. Thus, the thermodynamic calculations used in the current study appear to be reliable within the range of operating conditions and for the assumptions used.…”

“…De and Nag [13] determined that supplementary firing after the gas turbine, in order to increase the mass flow rate and the superheating of the steam, is unsuitable for most applications (especially at higher inlet temperatures). Tuma et al [14] reached similar conclusions when they determined the overall energy and exergy efficiencies of a combined gas-steam cycle, accounting for the reduction of power due to increasing the heat flow in supplementary firing at the gas turbine exhaust. The opportunity to verify these claims and to investigate other benefits of the supplementary firing are given importance in the current work in terms of coal utilization and CO 2 emissions.…”

A study of industrial steam process heating through exergy analysis

“…Numerous thermodynamic analysis and optimization studies using exergy have been undertaken of various thermal systems and processes in numerous sectors (Linnhoff and Eastwood, 1997;Urbaniec et al, 2000;Tuma et al, 2002;Risko, 2000;Hansen, 1999, 2000;Dincer and Al-Muslim, 2001;Rosen and Dincer, 2003;Tuma et al, 1999;Gyftopoulos and Widmer, 1980;Reistad, 1975;Fang et al, 1998;Scott, 1988a,b, 1998;Rosen, 1992;Rosen et al, 1988;Mathieu et al, 1995;Facchini et al, 1996). For example, exergy analysis has been used by the authors in a wide variety of applications, including thermal energy storage (Rosen et al, 1988), national macrosystems (Rosen, 1992), hydrogen, ammonia and methanol production Scott, 1988a, b, 1998), electricity generation (Dincer and Al-Muslim, 2001;Rosen and Dincer, 2003;Tuma et al, 1999;Gyftopoulos and Widmer, 1980;Reistad, 1975), and cogeneration (Rosen and Scott, 1988).…”

“…For example, exergy analysis has been used by the authors in a wide variety of applications, including thermal energy storage (Rosen et al, 1988), national macrosystems (Rosen, 1992), hydrogen, ammonia and methanol production Scott, 1988a, b, 1998), electricity generation (Dincer and Al-Muslim, 2001;Rosen and Dincer, 2003;Tuma et al, 1999;Gyftopoulos and Widmer, 1980;Reistad, 1975), and cogeneration (Rosen and Scott, 1988). Some studies demonstrate the extensive range of applications of exergy analysis for various systems and processes.…”

“…The expression enables estimation of the ratio of specific, but not absolute, costs. In another work, Tuma et al (1999) determine overall energy and exergy efficiencies of a combined gas-steam cycle, accounting for the reduction of power due to increasing the heat flow in the steam process, supplementary firing at the gas turbine exhaust, the heat recovery boiler efficiency and the heat exchanger efficiency in the gas and steam cycles.…”