Energy Integration of Multiple Effect Evaporators with Background Process and Appropriate Temperature Selection

• Published in: Industrial & engineering chemistry research 2016-02, Vol.55 (6), p.1630-1641
• Main Authors: Sharan, Prashant, Bandyopadhyay, Santanu
• Format: Article
• Language: English
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.5b03516

Multiple effect evaporators (MEEs) are energy intensive equipment. Often the focus is on minimizing the energy consumption of MEEs as a standalone system, rather than that of the entire plant. In this paper, process integration techniques are applied to integrate various stages of a MEE with the background process. To identify various energy conservation opportunities, the MEE is represented as a Grand Composite Curve (GCC) and integrated with the GCC of the background process. Change in utility consumption in the first effect, due to energy shift (in the GCC) between various effects, is determined in this paper. It is proved that for the minimum energy requirement all effects should be pinched. Using these mathematical results, a methodology for optimally integrating the MEE with the background process is developed. Furthermore, additional energy may be conserved by appropriately selecting effect temperatures. A methodology for appropriate selection of effect temperatures is also proposed in this paper. Applicability of the proposed methodologies is demonstrated through a case study. It is observed that 9.8% energy can be conserved by properly integrating an MEE with the background and an additional 25.87% of energy can be conserved by selecting optimal effect temperatures.