A one dimensional model based on fundamental principles of gas turbine thermodynamics and combustion processes was constructed to quantify the principle of exhaust gas recirculation (EGR) for NOx reduction. The model utilizes the commercial process simulation software ASPEN PLUS®. Employing a set of 8 reactions including the Zeldovich mechanism, the model predicted thermal NOx formation as function of amount of recirculation and the degree of recirculate cooling. Results show that addition of sufficient quantities of uncooled recirculate to the inlet air (i.e. EGR>∼4%) could significantly decrease NOx emissions but at a cost of lower thermal efficiency and specific work. Cooling the recirculate also reduced NOx at lower quantities of recirculation. This has also the benefit of decreasing losses in the thermal efficiency and in the specific work output. Comparison of a ‘rubber’ and ‘non-rubber’ gas turbine confirmed that residence time is one important factor in NOx formation.

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