Multi-objective optimisation of steam methane reforming considering stoichiometric ratio indicator for methanol production

This work proposes a novel configuration for steam methane reformers (SMR) in order to improve their syngas stoichiometric ratio (SR). This is a decisive element for methanol producers to increase their production tonnage. While the optimum theoretical SR value is around 2, many conventional SMRs operate far beyond this value due to thermodynamic equilibrium limitations. In the new SMR design CO2, which could be an industrial off gas, is injected into the reactor in multiple stages. The corresponding CO2 injection flow rate is determined by a multi-objective optimization method. The optimum flow rate at each stage is chosen to minimise abs (SR-2) while maintaining the CH4 conversion at its highest value (about 68%). Furthermore, the new design helps to improve the thermodynamic equilibrium conversion in SMR resulting in 33% more CO production. As well as this, the pressure drop along the new reactor is proved to be substantially lower than the conventional SMR.