AquoMin: A software tool for Mass-Exchange Networks targeting and design

Abstract

This study addresses the work developed at Process Integration Group of CPQ to build a software tool in the area of Pollution Prevention, regarding the Mass-Exchange Networks (MEN) targeting and design. Given a set of mass transfer operations and their limiting data, AquoMin can analyse different options to reduce fresh water consumption and minimise wastewater production. The available strategies to optimise these targets are (i) process without waste water reutilisation, (ii) process with waste reutilisation, and (iii) process with waste regeneration reuse. These options are analysed in two stages: first the targeting and then the design. The former stage uses algorithms based on pinch analysis to obtain the minimum consumption of external water and also the minimum wastewater production. These targets are then used in the second stage, the MEN design. The regeneration reuse strategy needs an extra step in the MEN design stage, which uses pinch analysis concepts to generate a mass balance model to obtain a set of optimal design parameters, the Split Operation Parameters (SOP). Furthermore, work on regeneration with recycle and reuse has been also developed. It was created a general algorithm to obtain the targets for this strategy: the external water source flowrate and the regeneration and recycle flowrate. A small AquoMin tutorial is presented using an Example Problem. The regeneration reuse strategy is focused and the methodology employed in both targeting and design stages were improved. Different scenarios evaluating the MEN structure's complexity and equipment cost were also developed and compared in the regeneration reuse strategy. In the regeneration recycle and reuse strategy, the Example Problem was used to emphasise a new option for the regeneration concentration value and the results of all the strategies are compared. Finally, a five operations’ Case Study was solved to obtain the targets and designs to accomplish the three Process Integration Strategies with a final reduction of 60% in the fresh water consumption.