Otimização de um complexo de produção de gás de síntese a partir de gás natural

Abstract

The increase in the demand for natural gas at global levels has stimulated several studies about the optimization of synthesis gas production. However, the ways of approaching this problem in the literature have several limitations, such as, process modeling restricted to the reactor, utilization of constant technical indices or simplified economic analysis. Aiming to fill these gaps, the purpose of this work is to propose a more general formulation for the solution of the process synthesis problem of a synthesis gas production complex, where it is presented three candidate technologies for the gas production, in addition to the possibility of selecting a CO2 removal unit. Two formulations are explored, one of them involves the minimization of the total annualized cost and the other involves a multi-objective problem that considers profit maximization and greenhouse gas emissions minimization. Both formulations are organized in a general structure, where the mass balances constraints are employed to describe the relations among the different units present in the superstructure. The behavior of each unit is represented in the optimization through a set of constraints associated to polynomial models. The parameters of these models were obtained through the application of a parameter estimation procedure employing data from a commercial simulator. The simulations for the generation of the set of points for the empirical process modeling are based on complete flowsheets. The problem formulation also contains a comprehensive economic assessment that considered fixed and variable operating costs in addition to fixed investment costs. The results show that the developed tool can be applied successfully for the determination of the least cost configuration of a natural gas processing complex. Additionally, a Pareto front of the design problem was generated to illustrate the utilization of the tool in the multi-objective optimization problem for the compromise between economic and environmental aspects.