Incorporating the occupational health in the optimization for the methanol process

Abstract

The analysis of social aspects, such as occupational health, is as important as economic and environmental criteria in the design of sustainable chemical processes. Occupational health analyzes the relationship between work and health while enabling the identification of hazards that can cause injuries due to chronic exposure of the workers. This paper presents a multi-objective optimization approach for the methanol production process from natural/shale gas, different alternatives are proposed for the process configurations based on different equipment and technologies. The objective functions consist of maximizing the net profit, minimizing the total annual CO2 emissions, and minimizing the occupational health hazard. The Process Route Healthiness Index is used to evaluate occupational health. The process model is developed using the Aspen HYSYS® process simulator. To carry out the optimization, a metaheuristic algorithm is used; the improved multi-objective differential evolution (I-MODE) algorithm was used with programming in Microsoft Excel visual basic for applications. Linking routines are established to enable the transfer of values of the process variables. A set of decision variables are established in a search interval whose manipulation has a considerable impact on the performance of the objective functions. The results offer feasible alternatives for the values of the search variables and show a considerable improvement in the specified objective functions. Different scenarios are proposed to prioritize each of the objectives for which the decision-maker can make a selection of the best values and the configuration that best suits specific interests.