Retrofit of Crude Units Preheating Trains: Mathematical Programming versus Pinch Technology

Abstract

This paper presents a comparison of two heat exchanger network retrofit methods as they are applied to crude units: the well-known and widely used Pinch Design Method (PDM) and a recently developed Heat Integration Transportation Model (HIT), a recently developed mathematical programming-based MILP model [Nguyen et al. Ind. Chem. Eng. Res. 2010, 49, 13]. We show that the three-step procedure (targeting, design, and evolution) used by Pinch Technology renders solutions with excessive and unrealistic splitting of streams as well as visibly less profit compared to the results of HIT.

Global Optimization of Heat Exchanger Networks. Part 2: Stages/Substages Superstructure with Variable Cp

“…14 In a nutshell, the structure obtained is likely to be different because pinch technology considers an average Cp and therefore at the end there is a violation of the minimum approach. The difficulties of the pinch design method are further explored by Bagajewicz et al 13…”

“…In addition, several methods, especially conceptual design methods, such as the Pinch Design Method (PDM), have inherent inabilities to be extended to consider it. , We discuss this issue in more detail later.…”

Improving the Energy Efficiency for Propane Recovery from Natural Gas using Pinch Technology: A Case Study

“…It is known that the choice of the minimum approach temperatures is a crucial factor in determining the total annual cost of HENs; as the temperature approach increases the utility cost increases and the capital cost decreases, and the reverse is true. Ahmed and Linnhoff [10] introduced the super targeting concept, i.e. choosing the optimum ∆Tmin that realizes the least annual cost ahead of design.…”

“…Considering the cold side of the pinch there are no cold streams reaching the pinch, i.e., no pinch matches are required; therefore, we are free to match any hot stream with any hot stream [9][10][11][12]. Figure6. shows the grid diagram with five pinches; only one pinch (101.7-93 o C) is the process pinch, others are utility pinches.…”

On the Minimum Number of Units in Heat Exchanger Networks

“…This article addresses the well-known formula for the minimum number of units that was proposed by Linnhoff et al and that has been used for the targeting of grassroots and retrofit designs of heat exchanger networks by enthusiasts of Pinch technology. We are not enthusiasts of the use of Pinch technology in all cases, but we recognize that fairly good results can be obtained for certain small systems, but we also know that it does not work well for other larger systems, especially crude units where there are significant problems . However, because there are still enthusiasts of this procedure and also because it works actually well for small systems, we present a counterexample where the minimum number of exchangers rule is violated.…”