A TWO STEP APPROACH TO OPTIMIZATION OF RECIRCULATING COOLING TOWER SYSTEM

• Main Author: JALANI, NOR FAIZAH
• Format: Thesis
• Language: English
• Published: 2012
• Online Access: http://utpedia.utp.edu.my/3035/1/THESIS-full-corrected-28_Dis_2011.pdf; http://utpedia.utp.edu.my/3035/
• Institution: Universiti Teknologi Petronas

Cooling tower is one of the unit that is involved with water network system and it can contribute to higher water savings for a plant if maximum attention is given to it. Much of the works only concentrate on individual cooling tower unit, especially in improving the performance of the internals. Nonetheless, work on the total cooling water system, which addresses the issues of interactions between the cooling tower and its associated heat exchangers or coolers, has received lesser attention. The objective of this study is to develop a systematic method for optimization strategy to improve efficiency of the existing cooling tower system, based on the established empirical model. A well-known Merkel’s Equation (Perry and Green, 1997) is used to predict the cooling tower performance. The basic idea in this optimization strategy is to minimize cooling water circulation in cooling tower through water reuse so as to maximize cooling tower return temperature. A two-stage approach is adopted in the optimization procedure. The first stage is to address the cooling tower performance itself. This effort takes into account the minimum approach temperature, pressure drop and fouling issues so that any modification of process parameters are within the acceptable limits of the cooling tower. In the second stage, cooling water composite curve, which is similar to a conventional water pinch technology, is proposed to identify water reuse opportunities. Further design of water reuse is carried out by mathematical approach using General Algebraic Modelling System (GAMS) mainly when composite curve unable to identify water reuse opportunity. Finally, the economics of the proposed improvement are then presented to demonstrate its cost effectiveness. Based on the case studies, application of water reuse enables the total operating cost of the cooling water systems to be reduced up to 27% for case study 1 and 28% for case study 2. While for case study 3, the additional product capacity could be obtained up to 15%. These findings show a great promise for industrial application as the methodology developed in this thesis can be used to improve the performance of the cooling water system.