The Study On The Production Of Mineral Heat Transfer Fluids By Direct Coal Liquefaction

After the direct liquefaction of coal by Shenhua Company,the mediate temperature solvent oil produced by the distillation column sideline and the alkyl oil from hydrogenation of the medium temperature solvent oil have proper distillation range and unique hydrocarbon types.So they can be properly processed to produce a variety of excellent products.This provides a new way for the production of high-temperature mineral heat transfer fluids.In this paper,the medium temperature solvent oil produced by direct coal liquefaction process,alkyl oil(1211)after hydrogenation of medium temperature solvent oil,stable oil of coal direct liquefaction and hydrogenation and other potential fractions for mineral heat transfer fluids are mainly studied.Their main physicochemical properties and thermal stability at 310 ? and 320 ? were investigated.The effects of distillation range and hydrocarbon types on the thermal stability were analyzed.And the effects of fraction blending on thermal stability were investigated.The experimental results show that the thermal stability of alicyclics and aromatic hydrocarbons with short side chain are good,while that of alkane and aromatics with long side chains are poor.In the ideal heat transfer fluids,the content of cycloalkane should be kept above 40%.The thermal stability of the base oil could be improved by converting components in the feedstock into ideal ones using hydrotreatment.In addition,the blending of different fractions can make the distillation ranges and hydrocarbon types more reasonable and hence improve thermal stability.The effects of different kinds of antioxidants on the thermal stability of direct coal liquefaction products were also investigated.The results show that both phenolic antioxidants and amine antioxidants contribute positively to the thermal stability of mineral heat transfers produced by coal liquefaction.One of the amine antioxidants gives the greatest effect on thermal stability so that the medium temperature solvent oil can meet the mineral heat transfer fluid specifications.