Algorithmic targeting for Total Site Heat Integration with variable energy supply/demand

Fluctuating renewable energy supply presents a challenge for applying energy-saving methodologies such as Process Integration. Graphical targeting procedures based on the Time Slices (TSLs) have been proposed in previous works to handle the energy supply/demand variability in TSHI. The targeting procedures for TSHI with TSLs include the construction of Composite Curves, Grand Composite Curve and Total Site Profile for each time interval. Heat Integration analysis utilising a numerical algorithm typically offers higher precision and more rapid calculations as compared to the graphical approach. This paper introduces an algorithm to efficiently perform utility targeting for a large-scale TSHI system involving renewable energy and variable energy supply/demand to include TSL. The presented tool is an extension of the Total Site Problem Table Algorithm (TS-PTA), which has been previously used for processes with steady energy supply/demand. Due to its algorithmic nature, the technique presented enables the accurate and rapid determination of the stream origins, and can be embedded into larger algorithms. Optimised heat storage facilities are used to manage the variable energy supply and demand. The Total Site Heat Storage Cascade (TS-HSC) is the core of the algorithm. The new developed tool is incorporated with the heat losses for the thermo-chemical energy storage systems. The process start-up and continuous operations are considered in the novel methodology. The tool is featured to analyse the heat excess in specific TSLs that can be cascaded to the next TSL via energy storage system during start-up and operation. The proposed tool can be also used to estimate the required heat storage capacity. (C) 2014 Elsevier Ltd. All rights reserved.