Debottlenecking Technique for Cooling Water Systems with Multiple Cooling Sources: Pressure Drop Consideration

Abstract

Cooling water systems are traditionally designed with a set of cooling water using operations arranged in parallel. Recent research has shown that this design can be improved and the cooling water system can be debottlenecked by employing the cooling water reuse/recycle philosophy. However, this can leads to high cooling water network pressure drop which is associated with additional reuse/recycle streams. This paper presents a technique to debottleneck a cooling water system with multiple cooling towers while maintaining a minimum pressure drop. The technique is based on critical path algorithm (CPA) and superstructural approach. The superstructure explore the opportunity for cooling water reuse/recycle while the CPA select the cooling water network with minimum pressure drop. This technique was previously applied in cooling water systems with single source however, in this paper the technique is adapted for a cooling water systems with multiple cooling sources. Furthermore, a cooling tower model is included to predict the thermal performance of the cooling towers. The developed mathematical formulations exhibit mixed integer nonlinear programming (MINLP) structure. The case study shows that up to 26% reduction in circulating cooling water flowrate can be realized with 3% improvement in cooling towers effectiveness. KEY WORDS Cooling water systems, optimizations, pressure drop, critical path algorithm.