Multi-product carbon footprint assessment for low-rank coal-based acetylene manufacturing process

The coal to acetylene process is still commonly used nowadays in some countries like China of which their energy structure relies deeply on coal. Compared with the coal to acetylene process using electro-thermal method in tradition, the oxygen-thermal method consumes less electricity and produces furnace gas with higher carbon monoxide (CO) purity. However, the potential to reduce carbon emission of the oxygen-thermal method is unclear which makes it necessary to evaluate the carbon footprint of oxygen-thermal coal to acetylene process. To accurately define the process is the first challenge in this research. Given that the coal to acetylene process generates acetylene and CO simultaneously, it is safe to regard this process as a multi-product process. Another challenge in this study is the shortage of relevant literatures on multi-product chemical processes, especially for the coal to acetylene process. In fact, a large majority of the current literatures try to use a general way to solve the ecological problems, which is not suitable for assessing the coal to acetylene process. Therefore, in this research, more attentions have been paid to adapting the traditional carbon footprint assessment to the coal to acetylene process, including selecting a proper boundary, collecting reasonable data and adopting appropriate allocation rules. The study examined the case based on the differences between the global warming potential (GWP) factors, the greenhouse gases (GHG) emission factors and the activity data of the systems, and noted that the GWP and GHG emission factors are usually regarded as given values while the activity data depends on characteristic parameters of the system. Thus, the activity data of the system should be verified repeatedly through the mass balance, carbon accounting and energy balance of the system. Moreover, individual contribution to the carbon footprint from each product should be considered in the aggregate carbon footprint, since the coal to acetylene process features multi-product outputs. Finally, recommendations for minimizing carbon emission of the system were presented.