Modelling of the combustion parameters of biogenous fuel gases to predict stable combustion conditions in multifuel systems

Lechner, Raphael Balthasar (2020). Modelling of the combustion parameters of biogenous fuel gases to predict stable combustion conditions in multifuel systems. University of Birmingham. Ph.D.

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Abstract

Classical fuel rating methods, such as the methane number or the related propane knock index were found to fail for the variety of biogenous fuel gas compositions encountered in practice. Thus, a novel methodology based on the detonation theory and the characteristic parameters chemical ignition delay, excitation time and laminar flame speed was adopted. The method enables an a priori, simulation-based determination of the knock propensity of fuels and centres on two dimensionless parameters which characterise the possible regimes of auto-ignition propagation from hot spots.

The methodology was applied to a range of 38 syngas and reference gas blends determined with a statistical mixture plan. To supplement the data, measurements were conducted at an intermediate pyrolysis plant featuring the Thermo-Catalytic Reforming technology developed at Fraunhofer UMSICHT. The required combustion parameters were obtained from detailed chemical kinetic simulations.

Syngas showed to be more prone to knock than methane or biogas, albeit less than propane. Admixtures of higher hydrocarbons were found to increase the knock propensity. Lean equivalence ratios, exhaust gas recirculation and the addition of water vapour were effective measures to mitigate the risk of knock.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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