(45c) Waste Motor Oil Pyrolysis for Clean Energy Generation in a Self Designed Pyrolyzer

Motor oil is an engine lubricant for heat transfer and friction reduction. But with use due to alteration in viscometric properties, they become unsuitable for further use and are discarded as waste. This discarded waste oil is detrimental to human health and the environment due to its carcinogenic, mutagenic, and regenerative properties. Thus, it demands sustainable waste management technology. Due to its high heating value, this waste oil can be used for clean energy generation using eco-friendly pyrolysis technology. Pyrolysis has gained attention for its flexibility and diverse product ranges.

Scope of the Study

This study assesses the feasibility of using WMO for clean energy generation in a self-designed pyrolyzer. Besides, the generated pyro-oil characteristics are compared with the diesel fuel properties.

Materials and Methods

The WMO was procured from the Tech Market within the Indian Institute of Technology Kharagpur (22.3 ËšN 87.3 ËšE), India premises. The feedstock was stored in an air-tight container for further use.

The designed pyrolyzer can be altered according to the researcher’s demand. However, in the present study, only the semi-batch approach is explored to optimize the pyro-oil yield. The overall efficiency of the pyrolysis process is influenced by its process parameters. The process parameters considered in this study are reactor temperature (T_R, °C), heating rate (β, °C/min), nitrogen flowrate (ν, LPM), and residence time (t, min). Besides, COMSOL Multiphysics was utilized to understand the rate of pyrolysis within the reactor. Lastly, the produced pyro-oil characteristics are compared with diesel fuel.

Results

The results show a continuous increase in pyro-oil yield from 9 to 82 wt% with an increase in T_R from 300 to 500 °C and a decrease in residue from 86.1 to 11 wt%. Similarly, an increase in pyro-oil yield from 82 to 90 wt% and a decrease in residue from 10.8 to 2.4 wt% was observed with an increase in heating rate from 4 to 8 °C/min. However, with an increase in ν and t, there is an increase in operational costs. So, balancing the economics with product yield, T_R = 500 °C, β = 8 °C/min, n = 0.6 LPM and t = 10 min is selected as the optimum process parameters. This increase in the decomposition is mainly due to the secondary reactions leading to a greater yield of the pyrolysis products. The COMSOL modelling, helps understand the reactor's temperature distribution and its co-relation with the product yield. Besides, the fuel properties of the generated pyro-oil are in line with commercial diesel fuels.

Implications

The finding of this research article will help design and develop a continuous and cost-effective pyrolyzer for recovering alternate energy, thereby increasing the sustainability of WMO pyrolysis in the future. Besides, the generated pyro-oil can be used as a transport fuel because of its diesel-like fuel properties.