Designing the microturbine engine for waste-derived fuels

Challenges and Solutions for Utilization of Bioliquids in Microturbines

“…Fuel properties that in general impose challenges when designing the fuel delivery system are: density, viscosity, heating value and fuel composition as well as its PH value [70]. First three parameters are considered when designing the fuel supply system, whereas the last two can significantly impact its durability.…”

“…This selection can be optimized with dedicated immersion test either under stationary or moving flow conditions. Different planned preheating temperatures can be tested and further analysis can be performed by investigating the SEM images of surfaces and cross sections of immersed material [70].…”

“…It also increases velocities and thus compensates for the increased volume of the combustion chamber being favorable for reducing fuel deposition on the combustion chamber walls. High primary air temperature is thus one of the main enablers for attaining successful combustion of highly viscous bioliquids [70]. The drawback of high primary air temperature might result in fuel nozzle deposit formation, as radiation of high temperature primary zone gasses provides up to 90% of heat transfer to the fuel nozzle [19] and thus deposit formation is highly likely with preheated fuels.…”

“…Therefore, this measure frequently needs to be combined with the application of thermal protection of the nozzle being addressed in the previous section. In terms of technical complexity of this adaptation, the state of the art commercial MGTs are proved to be an ideal starting point due to their high primary air temperature [70], however the adaptation of the fuel nozzle is required in most cases. In addition, increase in primary air temperature is generally attained through exhaust gas heat regeneration, which further boosts efficiency of the MGT.…”

“…The stability of operation can be assessed through time-resolved measurements of thermodynamic and emission parameters, namely combustion chamber pressure and CO, THC emissions and NOx emissions. An example of variation of key MGT parameters before/after introducing exhaust gas heat regeneration is given in Figure 5 (adopted from study with liquefied wood [70]), which clearly shows the increased variability of parameters if low primary air temperature (i.e. simple cycle operation) is used.…”