Study On Coking Of Residue With Recycling Of Hydrogen Donor Distillate

With the crude oils more deteriorated, how to efficiently process these unconventional petroleum has become a challenging project. The delayed coking technology has some unique advantages, however, the aspects of liquid yield and products distribution are not satisfactory. In order to optimize the technology and get reasonable processing method for coking distillates which are difficult to be process, this dissertation has studied the feasibility and advantages of blending distillate which have the ability of donating hydrogen with residue in a certain ratio for coking.First of all, a profound understand of hydrogen transfer was got, through studying on the hydrogen-donating abilities and hydrogen-capturing abilities of residue and distillate. The hydrogen transfer ability was closely related to structural average parameters and H/C ratio. With the time of thermal cracking increasing, the hydrogen- donating ability firstly experienced an raise, reaching the top ,and then decreased. The hydrogen-capturing ability was uniformly ascending. After comparing the hydrogen transfer ability, the results that KLVR has greater hydrogen ability than WVR, and WVR has greater hydrogen-capturing ability than KLVR. With thermal cracking temperature enhanced, the hydrogen-donating ability and hydrogen capturing ability became greater, and the time for getting top hydrogen-donating ability was cut down. The order for hydrogen-donating ability of different distillates: C>B>A. With adding distillate C at a fit ratio of 0.3:1, the hydrogen transfer reaction was improved apparently.By employing an autoclave with a sampling system, the coking trend of residue was investigated in detail. The results were shown as follow. During the coking induction period, the coking rate was small, but once beyond the period, the rate was big. With the temperature upgraded, the coking induction period was cut down. The coking trend for different residue were different, The coking induction period for KLVR was longer than WVR. Before reaching the coking starting point, the colloid stability decreased , but once beyond the point, the stability tend to be stable. The impact of adding distillates on the coking induction period and colloid stability of residue was consistent with the ability of hydrogen-donating ability.Dynamics behavior of KLVR and its SARA was studied by thermogravimetry (TG) method with industrial coking simulation device employed, the coking process was evaluated. From the curve of conversion ratio to temperature, the dramatic cracking temperature for SA, AR,RE and VR were 350℃—480℃, 375℃—485℃, 382℃—498℃, 375℃—492℃, respectively. The coking temperature for KLVR was confirmed as 500℃. The order for coking ratio of SARA:SA