Effect Of Air Preheat Temperature On Combustion Characteristics Of Biodiesel

Abstract:Research and utilization of biodiesel was an important direction in the development of energy, but biodiesel was mainly applied to the internal combustion engine, little study of its application in industrial furnaces and boilers. The physicochemical properties of biodiesel was better, can replace petrochemical liquid fuel.Combustion characteristics of biodiesel burning in furnace were studied in this paper, in order to drive the research and application progress in the field of industrial furnace.Thermal analysis experiments of diesel and0#diesel was carried on, the weight loss process of two kinds of fuel were studied, its combustion characteristics were analyzed and compared, activation energies were calculated.non-isothermal kinetic equation of biodiesel and0#diesel derived by Achar differential method and Coats-Redfern integral method. The results show that:1)the wightlessness of biodiesel was quick, decomposition and combustion is intense flammability of biodiesel was better than diesel;2) biodiesel weight loss process can be divided into two processes:light components volatile and heavy components combustion. the volatile content of biodiesel was much higher than diesel;3) for activation energies, the biodiesel was higher than the diesel at low temperatureperiod, andthermal stability for the biodiesel was better.The emission characteristics of biodiesel burning in the small furnace were studied, the law of the CO emission and NO emission under the influence of air preheat temperature T was obtained.The results show that:1) the temperature of the furnace increases with he combustion air temperature’increasing, and the time required to reach steady state decrease;2)the CO emissions first increases and then decreases with the temperature of the preheating air increases;3)the NO emissions decreases with the temperature of the preheating air increases, but the maximum was only44mg/m3.High-speed camera was used to capture images, and the flame characteristics was researched by digital image processing techniques and Matlab programming technology, the law of flame structure、length、area under the influence of combustion air temperature T was studied.The results show that:1) under normal temperature, flame structure was disperse, the front of flame was clearly broken.the flame structure was more compact and not easy to be broken, the flame was more bright with air preheat temperature T decreasing;2) Matlab software and threshold method were used to do image segmentation and obtain the flame length and area, the calculation results are accurate and reliable;3) the flame length first increase and then decreases:20-80℃, the average length of flame decreases;80-350℃, the average length of the flame increases but was lower than the length when the temperature was20℃;350-500℃, the flame length was greater than20℃, and the growth trend was more obvious;4)the law of flame area was like the length.