Conversion of Petroleum Coke in a High-Pressure Entrained-Flow Gasifier: Comparison of Computational Fluid Dynamics Model and Experiment

Abstract

High-pressure entrained-flow gasifier technology is used to convert solid carbonaceous feedstocks into synthesis gas, which can be used in an integrated gasification combined cycle power plant or as a feedstock for chemical or synthetic fuel production. Computational fluid dynamics (CFD) models, once validated, can be used to help design full-scale reactors. Model validation entails the comparison of model predictions to lab-scale or pilot-scale measurements. However, experimental measurements of high-pressure pilot-scale gasifiers usually consist only of wall temperatures and outlet gas temperature and composition, which are of limited use for model validation when the gasifier is operating well, providing information only about operating temperature, heat loss, and equilibrium gas composition. These do not provide a strong validation of the CFD model, whose main purpose is to make predictions of the flame size and shape and its ability to convert solid fuel to gas efficiently in a small volume. This paper presents a model validation based on data generated using CanmetENERGY’s 1 MWth high-pressure entrained-flow gasifier. To provide a stronger validation, the approach taken here is to compare the model predictions to the pilot-scale measurements over a range of operating conditions comprising higher (approximately 90%) carbon conversion and lower (approximately 80% or lower) carbon conversion. In effect, the comparison includes operating conditions for which gasification reactions are extended or delayed toward the outlet in order to capture key effects. It is found that the present CFD model is able to track the performance of the gasifier over the range of operating conditions and provides insight into the causes for limited carbon conversion.

Dry Petroleum Coke Gasification in a Pilot-Scale Entrained-Flow Gasifier and Inorganic Element Partitioning Model

“…11 A model incorporating kinetics can provide predictions closer to experimental values. 26,28 Predicted temperatures were only higher for tests V1d and V2c. For test V1d it is believed there was accumulated carbon from previous tests in the system, which would explain the apparent carbon conversion of 109% (Table 5) and lower-than-predicted temperature.…”

“…The achieved carbon conversions are generally lower than what is expected for commercial entrained-flow gasifier operation, i.e., 98− 99.5%, 48 due to system constraints at the pilot scale (e.g., high surface-to-volume ratio, pressure <20 bar), as well as the intentional use of unideal conditions to anchor various models. 26,28 Figure 2 shows various combinations of results in Table 5 as a function of the O:C molar ratio. The O:C ratio includes oxygen from the injected oxygen gas, steam and fuel, and carbon from the injected fuel.…”

“…The fuel conveying system was used for the tests in the current study Reduced order modeling 26,27 Develop a semicomprehensive gasifier model for rapid simulations Data from the current study was used to validate steady-state and dynamic reduced order models Computational fluid dynamics modeling 28 Develop a comprehensive gasifier model Data from the current study was used to validate a computational fluid dynamics model Energy & Fuels 4. These properties are averages with standard deviations for three samples taken from different barrels.…”

“…CFD simulations indicate that this deposition mainly occurs near TC1. 28 Hence a detailed thermodynamic calculation is performed at temperature TC1 considering the combination of all injected streams (i.e., stream C1 in Figure 6). The resulting phases are divided into stream G1 (i.e., the gas phase) and stream P1 (i.e., the combination of pure liquid, pure solid and solution phases).…”

Dry Fuel Jet Half-Angle Measurements and Correlation for an Entrained Flow Gasifier

“…Similarly, change in mean particle volume fraction is used to define the characteristics lengths of gas jets penetrating into a fluidized bed [29]. Also Two CFD simulations, with similar conditions as the experiments [28], were analyzed to determine the jet half-angle for reactive flow ( Table 3). The jet core in both cases remains at ambient temperature (~300 K), while the surrounding temperatures differ between the two cases; estimated at 1231 K and 1165 K for cases 1 and 2, respectively (Figure 7).…”