Nashrieh Shimi va Mohandesi Shimi Iran

Nashrieh Shimi va Mohandesi Shimi Iran

Simulation of Pyrolysis of Polymers in a Solid-Gas Fluidized Reactor Using Computational Fluid Dynamics

Document Type : Research Article

Authors
Sobhan Daefeh Jafari 1
Hadi Soltani 2
Motraza Gholizadeh 3
1 1Department of Chemical Engineering, Ahar Branch, Islamic Azad University, Ahar, I.R. IRAN
2 Department of Chemical Engineering, Faculty of Engineering, University of Maragheh, Maragheh, I.R. IRAN
3 Faculty of Chemical and Petroleum Engineering, University of Tabriz, Tabriz, I.R. IRAN
Abstract
The ever-increasing expansion of polymer products has led to serious environmental concerns due to the production of waste at the global level. One method of polymer waste management is utilizing the pyrolysis process, which is economically viable and can partially meet the fuel requirements of industries. In this regard, simulating this process is of greater importance in optimizing the efficiency of the products; however, due to its complexity, the numerical simulation of conical beds by multiphase gas-solid flow has received less attention. Therefore, this paper simulated the pyrolysis process of polymer waste in a conical solid-gas fluidized bed reactor using the computational fluid dynamics method. The Eulerian approach and the kinetic theory of granular flows were employed to simulate this multiphase system and the interactions between phases. The effect of various factors, including temperature, gas velocity, and particle size, was investigated. The results showed that temperature is the most important factor in the pyrolysis process; with an increase in temperature to 923 K, the highest amount of gas flow and the lowest amount of tar are produced, which yields favorable economic benefits. On the other hand, flow rate significantly affects the production process of the desired products due to its influence on temperature. At low speeds, particles absorb more heat due to increased contact with the wall, resulting in a faster increase in the temperature of the bed. Conversely, with a higher gas flow rate, more mixing occurs, and a larger volume of gas occupies the space between the solid particles, which leads to a decrease in heat transfer due to reduced particle contact and lower thermal conductivity. Therefore, the inlet flow rate should be set at the lowest optimal value. Additionally, the results showed that increasing the diameter of the particles from 1 to 3 mm causes the temperature to rise more steeply, leading to a faster heating of the bed.
Keywords
Pyrolysis
Fluid bed reactor
CFD simulation
Hydrodynamics
Heat transfer
Polymer

Subjects

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