(604f) A Systematic Approach for Conceptual and Sustainable Process Design: Production of Methanol

Methanol is an important bulk chemical and is widely used in a variety of consumer products. Methanol produced from renewable resources furthermore has the potential to be used as an additive to transportation fuels in order to meet the requirement that 10% of the energy used for transportation within the European Union is supplied from renewable resources[1]. A systematic hierarchal decomposition method is applied to design a sustainable and environmentally plant for producing methanol from the raw materials biomass and hydrogen produced by electrolysis. The method consists of 12 sequential tasks which take into account all stages of conceptual design, starting from the consideration of qualitative aspects of the process flowsheet and preliminary calculations to the detailed process simulations, equipment sizing, costing, economic evaluation, sustainability and LCA assessment of the designed process. At the end of task-9 (the economic analysis), the base case design is investigated for improvements with respect to heat integration and process optimization. In the final task-12, a sustainability and LCA analysis is performed to assess the environmental impact of the process design. This is done using software: SustainPro and LCASoft, that determine the key sustainability and LCA measures such as sustainability metrics for environment, economic and social; carbon footprint; safety index and many more. In addition, PRO/II is used for process simulation (for verification of design), ICAS for property prediction and analysis of design options. This procedure can be applied to design and/or analysis for new or existing chemical or biochemical processes. The process design decisions are made considering the sustainability and LCA issues together with the process design specifications. The conceptual process design of methylamines producing plant is performed as part of a MSc-level course on Process Design at the Department of Chemical and Biochemical Engineering at DTU under the supervision of Professor Rafiqul Gani.

The base case is estimated to be loss about 14 million US$ annually for production rates of 100,000 metric tons/year of methanol, primarily due to the high hydrogen price. In order for the base case process to reach breakeven the methanol prices has to increase to 25 %. The capital and operating costs are divided into the individual cost items in order to obtain which equipment and utilities contribute significantly to these costs. It is found that the heat exchangers are the most expensive equipment contributing to capital costs and the hot utility is the main contributor to the total operating cost. This information is then used as target for process improvement by heat integration and process optimization, thus increasing the annual profit and reducing the payback time. The environmental impact analysis identifies impact due to the release of chemicals and points to the need of better control mechanisms through the sustainable LCA analysis.

This poster presentation will highlight the development of a process flowsheet, including heat and mass balances, for the production of methanol from biomass. The heat and mass integration performed in order to minimize the production cost are presented together with a LCA analysis to determine the overall sustainability of the process.  

References:

[1] EU Directive (EC) 2009/28/EC of 23 April 2009, On the promotion of the use of energy from renewable sources