In addition to improving efficiency and reducing pollutant emissions, the cost-efficient use of fuels of different quality is one of the main goals in developing advanced, technical combustion technologies. Depending on the design concept of a specific combustion process, the composition of a fuel must fulfill certain specifications. This ensures that combustion proceeds in an optimal way with respect to emission behaviour and fuel efficiency, and that the combustion chamber is not damaged.
Fuel quality
Even the “simple” fuel natural gas shows the importance that “fuel quality” has for present-day power generation. The composition of natural gas varies very strongly depending on its source. Natural gas suppliers purify the natural gas and mix natural gases of different sources with regard to calorific value before delivering it to the power generation industry. Nevertheless, the exact composition is location-specific. For manufacturers of gas turbines, this raises the question as to which specifications the local natural gas at the site of operation must fulfill. What is the minimum fraction of methane, what are the maximum fractions of ethane and higher hydrocarbons? This is important because the higher the fraction of ethane and higher hydrocarbons, the higher the risk of flashback or self-ignition of the premixed natural gas / air blend.
Expensive component tests are ultimately necessary in order to specify the fuel quality. During the design phase, validated reaction mechanisms are used to check how the combustion properties at basic given conditions, such as preheat temperature and temperature, etc., are influenced by the composition of the natural gas. This is an essential step in the design of a combustion chamber concept. It helps to identify critical working points for a predetermined fuel composition, even at this early stage in development.
Providing validated chemical reaction mechanisms for natural gas is therefore one of the main tasks of the chemical kinetics group. By using these reaction mechanisms, it is possible to obtain an improved CFD design and to optimise technical combustion processes with regard to the fuel quality of conventional and alternative fuels, or of additives.