Simulation of the Two-Stage Pyrolysis Process of Mixed Waste Plastics

Abstract

Nowadays, "white pollution" waste plastics (WPs) have seriously damaged the ecological environment. Pyrolysis is an effective means of the resource utilization of WPs. Due to the complex composition of mixed WPs (containing chlorine), it is necessary to carry out fractional pyrolysis. This review numerically simulates the process of staged pyrolysis of mixed WPs. The simulation results show that at low speeds (1 rpm), the particles slide along the inner wall of the reactor as a whole. When the rotation speed is high (2, 3 rpm), the particle movement is dominated by the rolling mode. With the increase in the rotation speed of the reactor, the translational speed and rotational speed of the particles gradually increase. When the reactor speed is 2 and 3 rpm, the particle trajectory has relatively significant fluctuations up and down, indicating intense particle motion and frequent changes in particle position. At 3 rpm, the particles reach the highest temperature quickly with a short residence time. At 1 rpm, the particles have the longest residence time but a higher risk of coking. At 2 rpm, the heating rate is faster and can basically reach the temperature and residence time required for pyrolysis. The simulation results analyze the influence of reactor speed on the temperature and motion of mixed WP particles, providing guidance for the optimization of the mixed WP staged pyrolysis process.