Thermal analysis and new insights to support decision making in retrofit and relaxation of heat exchanger networks

Abstract

Please cite this article as: A. Piacentino. Thermal analysis and new insights to support decision making in retrofit and relaxation of heat exchanger networks, Applied Thermal Engineering (2011), doi: 10.1016/ j.applthermaleng.2011.07.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractPinch analysis offers a rational framework for identifying energy saving targets and designing efficient heat recovery networks, especially in process industry. Several scientists have contributed to improve and automate the original pinch method over the last decades, increasing its capability to deal with a number of specific issues; the expertise of the analyst,however, remains determinant in achievingoptimal results. In this paper a procedure for retrofit of existing networks is proposed, based on an integrate use of several techniques (either existing or innovative). The diagnosis of the existing network and of a "Minimum Energy Requirement" configuration emerges as a useful preliminary instrument for the retrofit study. Then, an innovative spider-type diagram is presented to identify a hierarchic order among a set of retrofit topologies and the most promising relaxation paths for each network topology. The procedure is aimed at offeringa conceptual-interpretative approach to energy analysts, to identify preferential routes in networks' retrofit (and exclude the least promising improvement directions of the existing network); it should be therefore conceived as alternative to algorithms for automatic optimization of heat exchanger networks. The focus is mainly put on the energetic performance of the different schemes (evaluated by thermal analysis of the involved heat exchangers), but the methodology finally enables the energy analyst to identify solutions achieving near-minimum total costs.

Heat Integration retrofit analysis—an oil refinery case study by Retrofit Tracing Grid Diagram

“…To evaluate those options a visualisation tool based on heat loading plot [11] and SRTD [13] has been proposed. In this work the Stream Grid Diagram [21] has been upgraded and extended including important properties for retrofit analysis.…”

“…Varbanov and Klemeš [10] set more detailed rules for path construction for retrofitting the HEN. Piacentino [11] developed a comprehensive approach consisting of four steps: 1) the data extraction and data acquisition, 2) the definition and diagnosis of a maximum energy recovery (MER) network and diagnosis of an existing network, 3) the identification and evaluation of retrofit topologies, and 4) the identification and evaluation of relaxed lay-out. An interesting innovative tool [11] is the heat loading plot that presents the streams temperature and heat capacity flowrate.…”

“…Piacentino [11] developed a comprehensive approach consisting of four steps: 1) the data extraction and data acquisition, 2) the definition and diagnosis of a maximum energy recovery (MER) network and diagnosis of an existing network, 3) the identification and evaluation of retrofit topologies, and 4) the identification and evaluation of relaxed lay-out. An interesting innovative tool [11] is the heat loading plot that presents the streams temperature and heat capacity flowrate. Lakshmanan and Bañares-Alcántara [12] presented a novel visualisation tool for HEN retrofit called Retrofit Thermodynamic Diagram (RTD), where the streams are presented as rectangles.…”

Improving the network pinch approach for heat exchanger network retrofit with bridge analysis

“…With enthalpy variation as a function of the Carnot factor (1‐Ta/T), the area between curves represents the exergy losses due to heat transfer to lower temperature. This diagram provides valuable information for the improvement of heat exchanger networks and the design of utility systems …”

Analysis of heat exchanger network for temperature fluctuation

“…And some auxiliary approaches regarding the retrofit of existing HENs, which were in strict relation with the problem of synthesis, were proposed. [12][13][14] However, none of the models described above can truly reflect the effects of temperature fluctuations on HEN operation. The inlet or outlet temperatures of process streams are fixed seldom over the entire lifetime.…”