Date of Award

2018

Document Type

Open Access Dissertation

Department

Chemical Engineering

First Advisor

Bihter Padak

Abstract

Syngas is a reliable energy source derived from the gasification of coal and other solid fuels. The feedstock type and the production process of syngas can affect the composition of syngas. Gas turbines utilizing high hydrogen content (HHC) fuels like syngas for power generation applications need to meet stringent pollutant emission standards, particularly with respect to nitrogen oxides (NOx). For gas turbine conditions, reliable experimental data, especially at high-pressure, is necessary for both generating accurate NOx prediction models and improving reaction pathways regarding the NOx chemistry. In this study, NOx formation in post-flame gases of syngas combustion at different conditions was studied. A series of experiments were performed at atmospheric pressure to create a basis for the experiments at elevated pressure. NOx formation from lean premixed syngas/air combustion with various stoichiometries (equivalence ratio between 0.5-1.0 and H2/CO ratio between 0.25-1.0) was investigated. Flame temperature and two-dimensional temperature distribution were measured under various conditions. Detailed NOx speciation data in the post-combustion zone was collected by Fourier transform infrared (FTIR) spectrometer. Additionally, a high-pressure burner facility was designed and fabricated. Syngas can contain diluents and small amounts of hydrocarbons, which can affect the NOx emissions in the post-flame region. In the present study, syngas consisting mainly of H2 vii and CO was blended prior to combustion with components such as nitric oxide (NO) and hydrocarbons including methane (CH4) and ethane (C2H6) and carbon dioxide (CO2) as a diluent at high pressure. NOx speciation measurements as well as temperature measurements in the post-flame region were conducted in presence of hydrocarbons and diluent at various pressures up to 15 bar. High-pressure speciation data obtained in this study can provide validation information needed for improving the kinetic models available in the literature by providing further constraints.

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