Suhui Li

Syngas Spark Ignition Behavior at Simulated Gas Turbine Startup Conditions

Syngas spark ignition experiments were conducted using a single nozzle model combustor under typical gas turbine startup conditions. Ignition performance was characterized by measuring lean ignition limits. Effects of fuel composition (H2, CO2, and N2) and inlet air flow velocity on ignition performance were investigated. Results show that H2 content and air flow velocity both have a strong impact on ignition performance. A small amount of H2 can significantly improve the ignition performance of syngas. Data analysis indicates that chemical time, rather than ignition delay time, is more suited for characterizing the reactivity of syngas influencing spark ignition performance. Effects of fuel composition and air flow velocity can be captured by a Damköhler number–flame temperature correlation. A 3-step ignition theory is proposed to explain the correlation. Compared to natural gas, syngas has a better ignition performance due to the presence of H2. Considering that gas turbines operating on syngas still have to start with natural gas or diesel, this study demonstrates that syngas is a promising ignition fuel for gas turbine startup.

A Large-Eddy Simulation-Linear-Eddy Model Study of Preferential Diffusion Processes in a Partially Premixed Swirling Combustor With Synthesis Gases

A lean partially premixed swirling combustor operated with synthesis gases is studied using large-eddy simulation (LES). The linear-eddy model (LEM) is employed to close the unresolved scalar fluxes with the nonunity Lewis number assumption. Several terms resulting from the LES filtering operation are not modeled but directly resolved considering their unique length and time scales, such as molecular diffusion, scalar mixing, and chemical reactions. First, the validation results on a well-established jet flame indicate a good level of correlation with the experimental data and allow a further analysis of syngas combustion on a practical combustor. Second, the effects of preferential diffusion on the characteristics of flow and combustion dynamics on a lean partially premixed swirling combustor are investigated. The obtained results are expected to provide useful information for the design and operation of gas turbine combustion systems using syngas fuels.

Gasification Studies Task 4 Topical Report, Utah Clean Coal Program

A key objective of the Task 4 activities has been to develop simulation tools to support development, troubleshooting and optimization of pressurized entrained-flow coal gasifiers. The overall gasifier models (Subtask 4.1) combine submodels for fluid flow (Subtask 4.2) and heat transfer (Subtask 4.3) with fundamental understanding of the chemical (Subtask 4.4) and physical (Subtask 4.5) processes that take place as coal particles are converted to synthesis gas and slag. However, it is important to be able to compare predictions from the models against data obtained from actual operating coal gasifiers, and Subtask 4.6 aims to provide an accessible, non-proprietary system, which can be operated over a wide range of conditions to provide well-characterized data for model validation.