Removal of VOCs from waste gases using various thermal oxidizers: A comparative study based on life cycle assessment and cost analysis in China

Abstract

Due to the long lifespan of thermal oxidizers (over 20 years), outdated facilities might still be operational. However, these oxidizers may not be energy efficient due to the lack of an energy recovery system. Thus, those outdated facilities need to be either retrofitted or replaced to decrease both energy and fuel consumption. In this regard, it is important to systematically assess the costs and environmental impact of the available technological options to promote more informed selection criteria for new oxidizers. Therefore, the environmental and economic performances of a recuperative thermal oxidizer and a catalytic thermal oxidizer were assessed in this study to provide a decision support tool for the selection of new incinerators.These two scenarios have been compared to an outdated thermal oxidizer such as a direct flame incinerator, which was selected as a baseline scenario. The life cycle assessment of the three oxidizers has been performed using SimaPro software according to the ReCiPe method at mid-point level (hierarchist). The main sources of impact for the considered oxidizers are the natural gas needed for the operation of the combustion chamber, electricity and gaseous emissions, including CO2, water and residual volatile organic compounds. The results indicated that both alternatives could significantly reduce the overall impact of the thermal oxidation process compared to the baseline case. However, the catalytic oxidation process emerged as the most sustainable technological option due to its lower fuel and electricity requirements. Moreover, the cost analysis of the scenarios considered clearly demonstrated that the catalytic oxidizer could represent the most cost effective alternative. This is due to its lower annual costs, which might offset the higher investment necessary to set-up a catalytic oxidizer within the first year of operation.