Chemical Properties,Low-Temperature Performance,and Burning Performance of Bio-Jet Fuel

The effects of composition of bio-jet fuels on freezing point,smoke point,distillation range,and flash point are investigated.Performance tests using petroleum-based jet fuel with different compositions are conducted in line with standard test specifications.The results show that alkylbenzenes reduce the freezing point,with the amount of reduction becoming greater with increasing alkylbenzene content.For a 25%content of the C_8 aromatic xylene,the freezing point is in the range from-55.5℃to-60.1℃.The presence of monocyclic aromatic hydrocarbons leads to an increase in carbon deposition performance,especially when alkyl side chains are present.With cycloalkanes,carbon deposition is reduced,although alkyl side chains weaken this beneficial effect.Isomeric hydrocarbons are beneficial in reducing carbon deposition.The ASTM D7566 specifications for the distillation range are based on the average properties of petroleum-based aviation fuel,and if all the parameters governing the distillation range of an alternative jet fuel are at their lower limits,it is necessary to check whether other performance standards are met.Light components affect the flash point greatly,with 5%of benzene reducing the flash point by 17℃,whereas intermediate components(e.g.,xylene and ethylbenzene)and heavier components have less impact.Although alcohols provide better combustion performance,their content must be strictly limited owing to their effects in reducing the flash point.

Pyrolysis of scrap tyres pretreated by waste coal tar

For disposal of scrap tyres,there have been a lot of studies done by previous researchers,but it yet remains a longstanding challenge in practice.To find a solution for this problem,the feasibility of a proposed approach in a laboratory scale was tested.The pyrolysis of scrap tyres pretreated by waste coal tar(noted as "as-pretreated" tyres)was performed in a batch reactor at atmospheric pressure.Waste coal tar was used to modify the scrap tyres to improve the pyrolysis efficiency of scrap tyres input and the quality of the product tar.The swelling behavior of scrap tyres soaked in waste coal tar at 10℃,effect of pyrolysis temperature on the product yields,and the synergies during pyrolysis of the as-pretreated tyres and co-pyrolysis of scrap tyres/waste coal tar mixture were all investigated in detail.The results observed found that by comparison of the calculated yields and the observed experimental yields for pyrolysis products,the synergy from co-pyrolysis of scrap tyres/waste coal tar mixture boosted the gas yield without increasing the tar yield.In contrast,the synergy during pyrolysis of the as-pretreated tyres could enhance the tar yield,but reduced the gas and char yields.According to the distillation range analyses of the tar,more light fractions were found in the tar from pyrolysis of the as-pretreated tyres,in which the gasoline fraction,diesel fraction and kerosene fraction were 38.4 wt%,46.8 wt%and 50.2 wt%,respectively.This work is expected to be helpful in further use of scrap tyres.