Achieving a More Sustainable Process Design for the Production of Methanol
Cristina Calvera Plaza, Marta Gonzalez Garcia, Ana Diez Callau, Emmanouil Papadakis*
Department of Chemical and Biochemical Engineering
Technical University of Denmark, DK-2800 Lyngby, Denmark
Methanol is an important chemical product because it can be used as a raw material for the production of other chemicals (1), for example dimethyl carbonate, formaldehyde and methyl tert-butyl ether and it is also one of the most produced bulk chemicals with an annual global production of 100 million metric tonnes per year (1). Methanol can be produced using different reaction paths, for example natural gas. If natural gas is used for methanol production then CO2 is produced, utilized and can be emitted. Therefore, achieving a more sustainable design for the production of methanol is beneficial in order to reduce the process CO2 carbon footprint.
Using a 12 step, systematic task-based approach for achieving sustainable process design, a process for the production of methanol with an annual production of 300,000 metric tonnes of methanol per year with minimum CO2 emissions is analysed and designed. The reaction path chosen for the production of methanol utilizes CO2 as raw material. The reactions are as follows:
The process description that uses the above reactions is explained. The first outlet stream from the reaction system is a multi-component mixture that consists of methanol, water and unreacted gases. First, the gases are separated using a flash and recycled to the reactor. Second, the methanol is purified using two distillation columns. In the first distillation, light components are separated and in the second one the water. This design is analysed for improvements and is referred to as the base case design.
The analysis consists of two parts, first an economic analysis and second, a sustainability analysis. The economic analysis provides the information in order to identify targets for improvement related to heat integration and process optimization, while the sustainability analysis (2) provides information for identification of (design) targets for achieving sustainable design, that is, for example, reduction in carbon footprint and LCA factors (global warming potential, toxicity, etc.) (3). The sustainability analysis consists of a sustainability and LCA analysis.
In this poster, the 12 task-based method for achieving (sustainable) process design will be presented and its application will be highlighted through the application of the production of methanol. The input and output related to each step will be presented.
1. Methanex Corporation: The Power of Agility. [on line] http://www.methanex.com.
2. SustainPro- A tool for systematic process analysis, generation and evaluation of sustainable design alternatives. Carvalho, A., Matos, H.A. y Gani, R. 8-27, s.l. : Computers & Chemical Engineering, 2013, Vol. 50.
3. Integration of life cycle assessment software with tools for economic and sustainability analyses and process simulation for sustainable process design. Kalakul, S., y otros. 98-109, s.l. : Journal of Cleaner Production, 2014, Vol. 71.