# Design of Pyrolysis Plant for Waste Methyl Ethyl Ketone from the Polarizer Manufacturing Process
## 3 Results and Discussion  
### Model of Lab-Scale System  
The main goal of this study is to ensure the continuous operation of MEK in the pyrolysis process while minimizing char and tar formation that may cause blockage. To achieve this, the reactor is designed based on the mini theoretical residence time, and the heat transfer phenomena are checked by calculating the flow zone using computational fluid dynamics (CFD). The overall heat transfer coefficient is determined by referring to the mass and heat transfer data of the ASHRAE Handbook [19] and Parry's handbooks [20] for the reactor and heat exchanger. The gas flow rate is calculated using the equation mentioned in Equation (13), and the length and diameter of the reactor are determined using various calculation methods listed in Table 1. The heat transfer properties of gas convection were analyzed using SOLIDWORKS flow simulation, which calculated the temperature and velocity responses. The reactor and cyclone-heat exchanger were evaluated separately. The boundary condition was set with a mass flow rate of approximately 36 g/min, assuming that one mole of MEK vaporized and cracked into four moles of gas molecules at high temperatures. The reactor (thermal cracking unit) calculation assumed adiabatic conditions, as the primary reaction zone was covered by the furnace. The barrel wall temperature was maintained isothermally due to a sufficient energy supply. The cyclone-heat exchanger unit calculation also assumed adiabatic conditions to ensure cooling capacity while disregarding the effects of natural convection and radiation. In Figure 5a, the results indicate the presence of a primary endothermic zone located at the bottom, with a temperature of approximately 650 \({}^{\circ}\)C. This temperature level provides sufficient energy for the evaporation and cracking of the solvent. Within the furnace, the barrel wall is maintained at 900 \({}^{\circ}\)C, and the heat from the furnace is transferred to the central tube. However, due to the spiral flow, the temperature distribution takes on a regular shape, resulting in a temperature difference of about 100-200 \({}^{\circ}\)C between the barrel wall and the central tube. The heat transfer near the central tube relies on the efficiency of heat transfer through the outer barrel. [PERSON] reported a similar heat transfer phenomenon in a tubular heat exchanger using SolidWorks flow simulation [21]. As the gas progresses towards the outlet, it undergoes counter-heat transfer with the feedstock, causing a decrease in its temperature. This energy exchange contributes to the preheating of the feedstock within the reactor. The gas velocity remains constant in the spiral section (Figure 5b), maintaining a consistent speed of approximately 1.5-2 m/s. This steady velocity promotes effective thermal diffusion and radiation, facilitating the decomposition of the feedstock. These temperature results indicate that the gases are adequately heated during the passing zone, promoting the reproducibility of the results. Following the temperature analysis, the heat exchanger was designed using Aspen Plus Exchanger Design and Rating (EDR), and the heat transfer coefficients were calculated using empirical equations, as shown in Table 2. Fouling factors were referred to from previous research by [PERSON] and [PERSON] [22] to account for potential thermal resistance that may increase over time. The results provided a highly credible scheme for building the facility, including amplification factors. The fouling factor, pressure drops, and actual/required area ratio were crucial in the sizing/rating project. Figure 6a presents the analysis of the cyclone-heat exchanger, illustrating its role in cooling the gas mixture. The swirling motion within the cyclone promotes heat transfer, thereby maintaining higher temperatures. With a gas velocity