(56b) Application of Self-Heat Recuperation to Industrial Methanol Synthesis Process

Many methanol synthesis processes have reactant recycle system with product separation to achieve high conversion ratio of the whole process, as well as other chemical processes. For this product separation from reactant recycle stream, a gas-liquid separator has often been used and distillation column has often been used for product purification. However, this gas-liquid separator and distillation column are well known as energy consuming processes. In fact, a huge amount of coolant is required for the cooler located between reactor and the gas-liquid separator in the methanol synthesis process. Furthermore, there are two distillation columns are normally located in the methanol synthesis process to purify the crude methanol and these columns consumed a large amount of energy. In addition, some of the exothermic reaction heat are utilized for the preheating of the reactant stream, leading to reduction of recovered heat amount by steam generation.

Authors have developed self-heat recuperation technology. In this technology, each process unit is divided into functions to analyze the process energy balance and not only the latent heat but also the sensible heat of the process stream can be circulated without any heat addition, leading to huge reduction of energy requirements in several chemical processes. This self-heat recuperation technology is suitable for thermal and separation processes and is applied to several chemical processes for energy saving as case studies.

In this research, we investigated the feasibility of applying self-heat recuperation technology to a methanol synthesis process using industrial conditions and data and developed an innovative process for methanol synthesis process from the energy saving point of view. By installing the self-heat recuperation technology to the methanol synthesis process, the energy consumption of the process can be greatly reduced. In addition, all of the exothermic reaction heat of the methanol synthesis can be recovered by steam generation.