Oxyfuel CFD Modelling

Computational Fluid Dynamics Modelling for Oxy-Fuel Combustion

Since 1997, Computational Fluid Dynamics (CFD) modelling has been an important component of CanmetENERGY’s oxy-fuel combustion research program. Oxy-fuel combustion is one of the advanced clean fossil fuel technologies to facilitate the generation of CO2 product stream ready for compression and storage. Oxy-fuel combustion has been an active area of our research and development for the past 15 years. The research program is being conducted partly under the CanmetENERGY CO2 R&D Consortium and also supported through different past and present government funding programs, such as the Climate Change Technology and Innovation Initiative and Natural Resources Canada’s Program of Energy Research and Development (PERD).

CFD modelling techniques are developed to provide analysis of fluid flow, mixing and reaction characteristics of a combustion system. Such details can be helpful to designers and operators to optimize system efficiency and longevity, reduce unwanted emissions, perform parametric studies and assess design performance prior to fabrication. Hence, they provide an opportunity to examine virtual prototypes and gain deeper insight into the behaviour and performance of new designs and systems. Oxy-fuel combustion typically involves oxidants like pure oxygen or highly enriched air; therefore, resulting in higher flame temperatures. CFD models can be particularly useful in exploring new and advanced design concepts for oxy-fuel burners, boilers and combustors and providing insights into combustion and pollutant formation thus facilitating shorter system design cycles by minimizing trial-and-error iterations. CFD can also complement experimental observation and data collection in oxy-fuel combustion systems.

Developing an Oxy-Fuel Modelling Capability

CanmetENGERY’s oxy-fuel CFD modelling capability is being developed closely with the experimental program conducted at Vertical Combustor Research Facility. This decade-long research collaboration has been mutually beneficial to the CFD analysts and the oxy-fuel system developers and designers. CFD models are used to help explain the fluid flow, mass and heat transfer interactions in these systems, compare and assess experimental results, optimize the experimental matrices and thus, reduce the cost and risks associated with new system development and experiments. On the other hand, experimental results help validate the existing CFD models and assumptions made therein; in turn promoting the development of new modeling theories.

measurement locations

Centreline Measurement locations

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Image 1

The measurement locations along the centreline of a down-fired vertical combustor, clustered in the flame region near the burner.

 
predicted temperature

Comparison of Measured and predicted temperature

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Image 2

A comparison of measured and CFD model temperatures demonstrates good agreement. The graph shows temperature versus distance from the burner along the combustor centreline, with the solid line representing the model prediction and the symbols representing the measurement.

 
predicted O2 levels

Comparison of measured and predicted O2 levels

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Image 3

A comparison of measured and CFD model oxygen levels demonstrates good agreement. The graph shows oxygen (% volume, dry) versus distance from the burner along the combustor centreline, with the solid line representing the model prediction and the symbols representing the measurement.

 

Applications of Oxy-Fuel CFD Modelling Capability

Current applications of CanmetENERGY’s CFD modelling capabilities include simulation of experimental configurations, supporting the development and troubleshooting of new oxy-fuel burner and combustor design configurations. These applications are all targeted towards efficient oxy-fuel systems with CO2 capture and storage.

temperature distribution

Temperature distribution for Two Burner Design

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Image 4

Temperature profiles for two burner designs are shown. The first burner design caused a hot zone at the side wall of the combustor. The second burner design created a more desirable centralized and axi-symmetric hot zone.

 
NOx Emissions

Evaluating NOx Emissions from Two Burner Design

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Image 5

NOx profiles for the two burner designs. The graph shows NOx concentration (parts-per-million, dry) versus distance from the burner along the combustor centreline. The non-axisymmtric burner produced slightly more NOx.

 

CFD modelling will continue to play an important role in contributing to the development of new oxy-fuel combustion concepts. Our researchers are continually looking at new ways of improving the CFD models to advance clean coal technologies and new application areas such as oxygen based coal gasification.

Managed by CanmetENERGY at the Ottawa (Ontario) Research Centre.