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A new Lagrangian conditional moment closure (CMC) model is developed for multiple Lagrangian groups of sequentially evaporating fuel in turbulent spray combustion. Flame group interaction is taken into account as premixed combustion by the eddy breakup (EBU) model in terms of the probability of finding flame groups in the burned and the unburned state. Evaporation source terms are included in the two phase conditional transport equations, although they turn out to have negligible influence on the mean temperature field during combustion. The Lagrangian CMC model is implemented in OpenFOAM [1] and validated for test cases in the Engine Combustion Network (ECN) [2,3]. Similar ignition delays and lift-off lengths are predicted by the incompletely stirred reactor (ISR) and the Eulerian CMC models due to relatively uniform conditional flame structure in the domain. The improved Lagrangian CMC model shows no abrupt reaction or oscillatory behaviour with an appropriate model constantKand gives results in better agreement with measurements lying between the predictions by ISR and Lagrangian CMC without flame group interaction. [ABSTRACT FROM AUTHOR]

This study reports the results of a detailed analysis of 203 samples of bioliquid used as a substitute for heavy fuel oil in oil-fired power plants. Bioliquid is a mixture of various vegetable oils, animal fats and its byproducts. The heating value of bioliquid is approximately the same as that of heavy fuel oil; however, bioliquid has significantly less N and S components and exhibits better combustion reactivity. For a commercial electricity generation, demonstration tests firing bioliquid in 75, 90, and 100 MW oil-fired boilers were conducted, and the results were compared with those obtained by firing heavy fuel oil. Further, the impacts of bioliquid fuel characteristics on combustion and boiler operation were also investigated. During the bioliquid firing, the heat absorption in the furnace decreased and the furnace exit gas temperature increased in comparison to the heavy fuel oil firing. No serious problems occurred in the boiler operation, and NOx and SOx emissions remarkably decreased. With minor modifications on the fuel transfer system and atomization devices, bioliquid could successfully replace heavy fuel oil in the existing oil-fired boilers. The limited values for 18 fuel properties of bioliquid are suggested by considering the stable boiler operation and environmental safety. • The characteristics of 203 bioliquid samples are analyzed compared to heavy fuel oil. • Kinematic viscosity and heating value of bioliquid are 8 and 89% of heavy fuel oil. • Bioliquids can be burned in heavy fuel oil fired boilers with minor modifications. • Emissions are reduced by 30% for NOx and 93% for SOx with lower fuel-N and –S. • Specifications are proposed for bioliquid fuel used in heavy fuel oil fired boilers. [ABSTRACT FROM AUTHOR]

This study compared the combustion characteristics between bioliquid and heavy fuel oil using a 0.7 MWth pilot furnace and a 75 MWe power generation boiler. The bioliquid flame in the pilot furnace was clearer and more transparent, but higher gas temperature in the burner zone, compared to the heavy fuel oil flame. It might be due to higher sooting tendency of the heavy fuel oil flame. Due to the lower N and S contents in bioliquid, NOx and SOx emissions were significantly reduced in the bioliquid combustion tests. For the bioliquid demonstration in a 75 MWe power generation boiler, bioliquid firing led to decrease in heat flux to the furnace wall, so the furnace exit gas temperature was increased, comparing to the heavy fuel oil firing. Subsequently, the heat absorption in the first pass of the boiler was increased and finally it led to the increase in reheater de-superheating water spray flow rate. Significant reductions in NOx and SOx emissions were achieved with bioliquid firing. The operation and measured data in the bioliquid demonstration tests showed the successful operation of the unit, and no operational or emissions limitations were identified. • The combustion characteristics of bioliquid were compared to those of heavy fuel oil. • The bioliquid flame was clearer and more transparent due to lower sooting tendency. • Significant reductions in NOx and SOx were achieved with bioliquid firing. • Bioliquid firing tests at 79 MWe showed no operational or emissions limitations. [ABSTRACT FROM AUTHOR]

This paper investigated the combustion and emission characteristics of a reprocessed used lubricating oil (RULO) with a pilot combustion test furnace to assess the possibility for using it as a fuel for boiler cold start-up operation. Results were compared with those of a by-product fuel oil (BFO) presently used in the power plant. Fuel analysis and testing showed that both oils had similar fuel properties, but RULO represented less reactivity and larger sprayed particle diameter than BFO. The cold start-up combustion tests revealed that RULO was ignited later and furnace exit temperatures was higher in RULO combustion, compared to those in BFO combustion. NOx emission in RULO combustion was about 10 ppm higher due to the higher fuel-N, and particulate emissions, thought to be agglomerated unburned carbonaceous particles, were severer in RULO combustion test than BFO combustion test. The relative comparisons between two fuel oils would provide a basic information for substituting an existing fuel oil to a renewable fuel oil during the start-up operation of the coal-fired power plant. • Fuel characteristics of a reprocessed used lubricating oil (RULO) was investigated. • Combustion characteristics of RULO were compared to those of by-product fuel oil (BFO). • RULO exhibited a reasonable combustion performance, compared to BFO. • Particulate emissions were severe during the RULO cold combustion test. [ABSTRACT FROM AUTHOR]