Combustor outlet temperature

The calculation procedure consists of a determination of the air/fuel molar ratio that will result in a combustor outlet temperature of 2000F, followed by the calculation of enthalpy and entropy of flow streams at the various state points in the cycle. The net work output from the turbine is calculated by subtracting the compressor work requirements from the total turbine expansion work determined from the enthalpy balance. Irreversible entropy productions are calculated by a routine entropy balance around each process step. 

This system was recently demonstrated in a real 150-kW engine during more than 200 hours at 1100 C combustor outlet temperature [53] at NOx levels below 15 ppmv at 15% oxygen. A schematic view of a multimonolith combu.stor is given in Fig. 10 [106]. 

The operating conditions for the gas turbine determine many of the desirable characteristics of the catalyst used in the catalytic combustor. The catalyst must be sufficiently active to operate at the lowest possible inlet temperature, preferably below 400 °C, in order to minimize the use of the prebumer. Unless the catalyst temperature is limited by some means, the catalyst must also be able to withstand the combustor outlet temperature of 1300°C. The catalyst must also operate efficiently at the very high gas velocities in the combustor. 

The problems encountered in developing catalysts for fully catalytic combustion have led to the development of various design approaches in which the catalyst temperature stays below the combustor outlet temperature. These approaches are described in the following sections. 

In test runs simulating actual gas turbine conditions this approach produced less than Ippm NO with a combustor outlet temperature of 1400 °C [14]. Even at a combustor outlet temperature of 1500 °C NO levels were only 2.2 ppm, indicating that this approach will also be applicable to the next generation of gas turbines with higher inlet temperatures. In addition, the low catalyst temperature allows the use of metal substrates, which are resistant to thermal shock, and produces a durable, high-activity catalyst system. 

The disadvantage of metallic monoliths is that their maximum operating temperatures are substantially below the 1300 °C combustor outlet temperature required for current gas turbines. They can therefore only be used in combustor designs that limit the catalyst wall temperature in some way, such as the hybrid combustors described above in Section 3.4. 

A consortium of Japanese electric utilities is developing the IGC process with financial support from the Japanese government. A large (200 t/d) pilot plant is operating at the Nakoso Power Station in Iwaki City, Japan. This plant includes a hot gas cleanup system and a 13 MW combustion turbine with a combustor outlet temperature of 2,300°F. The hot gas desulfurization system recovers elemental sulfur which is a better form of sulfur... 

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