Isotropic Pitch Softening Point via Annular-Mist Flow

The patent extracts and removes lower molecular weight components from isotropic pitch through evaporation and distillation processes. By selectively removing these lighter components (through flash evaporation, distillation, or extraction with solvents), the softening point of the remaining pitch increases while minimizing the formation of mesophase pitch, thus resolving the contradiction between increasing softening point and preventing harmful impurity formation.

The patent changes physical parameters such as temperature, pressure, and residence time to control the evaporation and separation processes. By optimizing these parameters (e.g., using vacuum distillation to reduce operating temperature, or controlling flash evaporation conditions), the process increases softening point while preventing the thermal conditions that would otherwise cause mesophase pitch formation.

The patent employs flash evaporation as a rapid separation process that achieves component removal in a single brief exposure to elevated temperature and reduced pressure, skipping the need for prolonged distillation. This rushing through the separation process in one step significantly reduces both capital equipment requirements and operating costs compared to conventional multi-stage distillation, while still achieving the desired softening point increase.

The patent uses relatively simple and inexpensive equipment configurations (such as flash evaporation vessels or single-stage distillation columns) rather than complex, expensive continuous distillation systems. These simpler processes achieve the necessary separation with lower capital investment and reduced operating complexity, making the manufacturing more economical while still effectively increasing softening point.