Experimental investigation of the prevaporized premixed (vpl) combustion process for liquid fuel lean combustion

A novel concept for the preparation of liquid fuels for an environmentally benign combustion process has been developed. This concept, called ‘VPL’ (Vaporized Premixed Lean) combustion, consists of: 1. a separate fuel flash vaporizer in which the liquid fuel is converted to the gaseous state; 2. a static mixing device for homogeneous mixing of fuel vapor and combustion air; 3. a burner in premixed mode, thus resulting in low NOx emissions. Various liquid fuels (diesel, kerosene, gasoline fractions and alcohols, etc.) could be completely vaporized under pressures up to 30 bar by adding superheated steam as the atomizing gas into the flash vaporizer. For lean, premixed combustion, the main source of NOx emissions is fuel bound nitrogen in fuel oil. Gas chromatographic analysis showed that endothermic thermal cracking of hydrocarbons in the oil fraction occurred, leading to increased heating values of the oil fractions. The overall thermal efficiency of the VPL-combustion process could be increased by using the hot exhaust gases from the gas turbine for heating and vaporizing the liquid fuels.