(604d) A Systematic Approach for Conceptual and Sustainable Process Design: Production of Methylamines From Methanol and Ammonia

Methylamines are very important chemicals as they are commonly used as intermediates for a wide range of agricultural chemicals, animal nutrients, catalysts, electronics, explosives, fuel additives as well as gas and oil treatments.

A systematic method is applied to design a sustainable and environmentally acceptable plant for producing mono-methylamines, di-methylamines and tri-methylamines from methanol and ammonia. The systematic method divides the process design work into 12 sequential tasks that covers 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, an economic evaluation, and, sustainability and LCE assessment of the designed process. At the end of task-9, the base case design is obtained, which is then further refined and improved 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 through the following special 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; ECON for cost and economic analysis. 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.

The annual profit of base case is estimated to be about 28 million US$ with a payback time of 2.5 years for production rates of 9792 metric tons/year, 33864 metric tons/year and  8976 metric tons/year of mono-methylamines, di-methylamines and tri-methylamines, respectively. The capital and operating costs are divided into the individual cost items. It is found that compressors are the most expensive equipment and the steam 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.

The design project was carried out under the supervision of Professor Rafiqul Gani.