Water Sources Diagram in Multiple Contaminant Processes: Maximum Reuse

Abstract

Water scarcity, rising energy costs, and stricter regulations on disposal of industrial effluents have forced a focus on the water usage in process plants. In this context, the development of methodologies to analyze the possibility of water reuse in industrial processes, considering the presence of multiple contaminants, has became an important issue for process engineers. There are a great variety of methods to deal with this problem, and they can be divided in two groups: algorithmic methods and mathematical programming methods. The problem with multiple contaminants becomes more complex, and the available algorithmic procedures are sometimes cumbersome; the methodologies based on mathematical programming present complex formulation and solving algorithms. This paper presents an extension of the algorithmic procedure water source diagram (WSD) to multiple contaminant processes. The proposed extended WSD procedure synthesizes water mass exchange networks for multiple contaminant processes, focusing on water reuse. It also targets the minimum water consumption and simultaneously makes the synthesis of the corresponding water network. The proposed procedure was applied in different examples used in the literature by others authors when discussing their proposals. Confrontation of results shows that the methodology here proposed has very good performance.

Water Sources Diagram and Its Applications

“…The minimum water flowrate from the external source p in each interval can be calculated according to Equation (4).…”

“…Those methods are better in the sense that they can find a solution that is close to the global one and the engineer needs little prior knowledge to understand how the units of the system are built ("black box"). The Water Sources Diagram (WSD) is a method which can provide engineering insights through a diagram analysis and, at the same time, generate the water network flowsheet [4]. Since the original idea proposed by Wang and Smith [5] of having a pinch point determined for water systems, graphical and other algorithm-heuristic methods have emerged, but none of them provide good results when dealing with problems with many contaminants.…”

“…Those improvements were also motivated by the feedback given by several kinds of companies where WSD was employed. WSD presented good results in regeneration processes [11,12], integrating water-thermal networks [13], in regeneration equipment [14] in oil refineries [4,7,15], in batch processes [16], pulp and paper facilities [8,17,18], in textile industry [19] and in a thermoelectric plant [20].…”

Process integration for industrial water reuse: A case study from a Brazilian biodiesel commercial plant

“…It should be said that information about industrial water consumption in Brazil is scarce because water is still a cheap feedstock. The algorithm used here to generate the water source diagram for the water allocation problem with the multiple contaminants is based on that proposed by Gomes et al (2013), which identifies a reference contaminant as a basis to describe the mass transfer of all other contaminants, adopting a linear mass transfer relationship.…”

“…Recently, the P+WATER method has been coupled with Water Sources Diagram (WSD) for multiple contaminants (GOMES et al, 2013). It constitutes a powerful tool for process integration towards industrial water reuse but it has not been applied to several processes such as biodiesel production yet.…”