Increasing concerns over global climate change due to greater amounts of greenhouse gases in the atmosphere or ozone depletion etc. are leading engineers to address `environmental' impacts of industrial processes. Additionally, the impact on ecosystems on which people depend and consequently the health of people is another growing concern. Furthermore, the `economics' of the industrial processes were dictated as the main constraint in the design of chemical process plants. However, recently health, safety, and public welfare or in other words the `social' concern is included as another important constraint. Addressing environmental, social, and economic concerns falls under the evaluation of sustainability of industrial processes. With all these concerns, engineers are developing novel methods for chemical process design. A methodology for evaluating the sustainability of processes was demonstrated using the SUSTAINABILITY EVALUATOR (SE) in conjunction with Aspen Plus process simulator. The SE is a Microsoft Excel based tool that requires mass and energy flows from Aspen Plus as inputs to the tool. The outputs from the tool include the economic, environmental, social, and overall sustainability impacts. The goal of using this tool is to assist decision makers or processes designers in quantifying the sustainability of processes and providing them with the ability to improve the process' sustainability. The methodology includes simulating a process in Aspen Plus, evaluating the sustainability using the SE, conducting a sensitivity analysis and subsequently optimizing the process in Aspen Plus, and finally re-evaluating the sustainability of the process using the SE. This methodology was demonstrated on a case study involving two different chemistries to produce methyl chloride; hydrochlorination of methanol and thermal chlorination of methane. The different chemistries were chosen to assist a process engineer in making a decision regarding the sustainability of a process e.g. whether one process is more sustainable than another. The SE tool addresses sustainability concerns and quantifies them in order to measure changes in sustainability of a process. The study found the process with the hydrochlorination of methanol chemistry to have a lower overall sustainability impact than the process with the thermal chlorination of methane chemistry. The lower the overall sustainability impact, the more sustainable is the process.School of Chemical Engineerin
