(117j) Development of 0.1 Ton/Day Plastic Pyrolysis-Combustion System of Circulated Fluidized Bed Reactor

With the modernization of industry and continuous global population growth, the demand for plastic consumption has been steadily increasing due to its light weight, ease of use, low cost, easy manufacturing, corrosive resistance, and structural characteristics. The huge amount of plastic usage is a serious issue, polluting environment and negatively accelerating GHG emissions. A chemical recycling of plastic waste is one good way to resolve the issue by converting wastes into reusable chemicals such as liquid fuel and naphtha chemicals over pyrolysis reaction. The major reactor of most commercial scale pyrolysis is kiln or screw type process that requires external energy from pyrolysis gas and oil or electricity by transferring heat from gas to solid waste (low heat transfer efficiency). In this study, a combined pyrolysis-combustion conceptual circulated fluidized bed system is proposed. Studies with four different experiment setups are designed and planned for the proof-of-concept. Once the concept is proof, over 0.1 ton/day scale system is scheduled to be developed in the following year (2022-2023). The goals for this project are, (1) auto-thermal process of pyrolysis (no solid char are being discharged and no external energy is supported for pyrolysis), (2) compact circulated fluidized bed system by applying inner loopseal system instead of outer one, (3) over 40% naphtha range chemicals, produced in the produced pyrolysis oil, and (4) CO₂ capture ready system. To achieve four goals, three experimental setups are developed and one experimental is planned to be constructed based on the results from the other setups. First, a hydrodynamic study is being conducted to investigate the controllable ranges of solid circulation rate, which is important factor to maintain the desired temperature of pyrolysis in bubbling fluidization chamber and combustion in turbulent chamber. Another important experiment with the hydrodynamic study is the gas mixing ratios between two reaction chambers. Second, a bubbling fluidized bed reactor was ready to investigate the plastic pyrolysis performance including the effect of waste feeding rate, residence time, temperature, fluidizing gas velocity, fluidizing bed material and plastic type. Third, the development of the heterogeneous catalyst for pyrolysis fuel reforming or upgrading is going on to find a proper catalyst to increase the light chemicals by breaking pyrolysis fuel wax. Last, a circulated fluidized bed system with inner-side loopseal is going to be designed based on the experiment results obtained with the three experimental setups. Then the system is built to evaluate the temperature balance between combustion of solid char and pyrolysis to verify the energy transfer rate simulation. This study suggested that plastic pyrolysis can be conducted using compact circulated fluidizing reactor to increase process efficiency, to maximize the liquid fuel product yield and not to discharge any solid black carbon.