The role of superheated steam in the thermopolycondensation of heavy gasoline-pyrolysis resins

A study is made of the influence of superheated steam flow rate on the group-components accumulation kinetics, softening point and yield of pitches obtained by the thermopolycondensation of heavy pyrolysis resins. The injection of steam with a continuous increase in temperature helps accelerate the removal of volatile and low-temperature components from the pitch and reduce the time of formation of pitch having a fixed softening point while also reducing the carbene content of the pitch. It is shown that steam acts as a turbulator. The unit steam injection rate and the quality of dispersion and distribution of the steam in the liquid phase are more important factors than steam temperature. In order to produce fiberforming pitches, the isothermal stage of the thermopolycondensation of heavy pyrolysis resins should be carried out for 8–10 h with temperatures between 340 and 380°C, pressures up to 1 MPa, and an hourly consumption of 0.02-0.04 kg of superheated steam per kilogram of feedstock.