شبیه‌سازی پدیده رسوب‌گرفتگی در راکتور پلی‌اتیلن سبک پتروشیمی کردستان

Low-density polyethylene is a subset of polyethylene that is mainly used in the plastics industry. These polymers are formed at high pressures and temperatures using a radical reaction. The fouling phenomenon is the result of the thermodynamic phase separation of polymer and ethylene. This phase separation occurs in the wall area (wall close to the cooling flow) of the tubular reactor, which reduces heat transfer to the reactor jacket, reducing production and in critical cases dangerous decomposition of ethylene. The purpose of this study is to simulate the phenomenon of fouling and its effects on the temperature and pressure of the reactor based on the heat transfer problems. The solved mathematical model is formed based on heat transfer equations to solve the computational fluid dynamics equations which are used to calculate the phase equilibrium data for pressure and temperature. The obtained results show that by increasing the thickness of the fouling, the heat transfer rate decreases. The operating model was used based on the low-density polyethylene with a grade of 2420H.

Based on the model, it was found that with increasing the thickness of fouling from 0.1 to 1.2 mm, the outlet temperature of the reactor increases, but does not have a significant effect on the pressure drop inside the reactor. Moreover, 10 °C increase in reaction temperature caused the volume percentage of the second phase (fouling) is reduced from 0.1833 to 0.1818 mm.