(210e) Development of DME Production Process Using Self-Heat Recuperation

The demand for dimethyl ether (DME) will continue increasing, since DME is categorized as one of the green energy sources. In fact, DME contains 34.8% oxygenates and has higher heat value than natural gas. Moreover, it is less toxic to human beings and can be stored as a liquid fuel with pressurising or cooling. DME is commonly produced by two methods; indirect and direct DME synthesis methods. In the indirect method called double stage method, methanol is produced and then converted to DME. On the other hand, in direct method called single stage method, DME is synthesised from syngas. The main advantage of direct method is reported that the CO transformation rate is higher than the indirect method. Thus, many investigators try to find or create new catalysts for direct method. However, this CO high transformation phenomenon occurs due to series reactions taking place in the reactor, leading to shifting the reaction equilibrium to the product side.

So, as well as other chemical processes, many DME production processes in the indirect method have reactant recycle system with product separation in order to increasing the overall conversion ratio in the reactor. Distillation processes have often been used for this product separation from reactant recycle stream in industry due to the large throughput. However, the distillation processes are well known as energy consuming processes since the large latent heat has to be provided to reach at the gas-liquid equilibrium in the column. Thus, many chemical engineers and investigators have been managing to produce a catalyst which achieves high conversion from reactant to production in the reactor for whole process optimization.

Recently, authors have developed a self-heat recuperation technology based on exergy destruction minimization to reduce the energy consumption of chemical processes. Applying the self-heat recuperation technology to chemical processes, not only the latent heat but also the sensible heat of the process stream can be circulated into the processes without any heat addition. As a result, the energy consumption and exergy destruction of a process can be greatly reduced in the steady state. In fact, this technology has been applied to several chemical processes as case studies and shows large energy saving potentials in these processes. From these previous studies, it found that thermal and separation processes are suitable processes for self-heat recuperation technology.

In this research, we investigated the feasibility of applying self-heat recuperation technology to DME production process and developed an innovative process for DME production process from the energy saving point of view. By installing the self-heat recuperation technology to the DME production process, the energy consumption of the thermal and separation processes can be greatly reduced. This process has a great potential to produce green fuel, DME with low energy consumption. In addition, if we will integrate the proposed DME production process based on self-heat recuperation with the methanol production process based on self-heat recuperation as the series of processes from syngas to DME, this series of processes has great potential instead of current direct DME production method from syngas.