Retrofit design of a pharmaceutical batch process improving green process chemistry engineering principles

摘要

Rapid globalization during the last decades and increasing regulatory efforts from governments forced the chemical industry to meet up the rising concern about sustainability aspects of chemical process design. Besides these non-monetary issues, the economic performance is still a very crucial aspect of design. Therefore, considering the capital intensive nature of chemical industry, redesign of existing production plants has been recently regarded as a key strategic decision. This retrofitting task has been extensively performed in continuous processes for the production of bulk chemicals, however in the case of batch processes and specialty chemicals only few studies address the importance of retrofitting, especially including multi-criteria sustainability assessment. The objective of this paper is to address retrofitting actions to enhance both monetary and non-monetary aspects of chemical process design. This is done using a systematic Path Flow Decomposition (PFD) method, multi-dimensional process assessment indicators, heuristics, and model based methodologies for generation of design alternatives. In this study a set of Environmental, Health, and Safety (EHS) hazard assessment and Life Cycle Impact Assessment (LC1A) indicators is newly introduced in the PFD method and evaluated in parallel with previously developed indicators. This set of indicators has been associated with a set of heuristics based on hazard and life cycle impact assessment rules and established principles of green chemistry and engineering. The developed methodology is applied to an existent batch production plant from pharmaceutical industry by addressing three process flowsheet structural alternatives for waste solvent management, pressure swing distillation, extractive distillation, and extraction for the separation of the THF/Water azeotrope. It is found that the suggested structural alternatives result in improved EHS, LCIA, and cost metrics compared to the base case of solvent incineration.