Characterization and visualization of industrial excess heat for different levels of on‐site process heat recovery

Abstract

Summary Increased utilization of industrial excess heat (or waste heat) can reduce primary energy use and thereby contribute to reaching energy and climate targets. To estimate the potential availability of industrial excess heat, it is necessary to capture the significant heterogeneity of the industrial sector. This requires the development of methodologies based on case study assessments of individual plants, adopting a systematic approach and consistent assumptions. Since the recovery of excess heat for power generation or off‐site delivery competes with internal recovery for on‐site fuel savings, a well‐founded approach should enable a comparison of the excess heat availability at different levels of internal process heat recovery. To determine the best solution for excess heat utilization for a given process, there is a need for easy screening of various options, while considering that some techniques require heat at a constant temperature while others can exploit a nonisothermal heat supply. This paper presents a new tool, the excess heat temperature (XHT) signature, for exploring the potential heat availability and trade‐offs for excess heat utilization by weighting the heat according to predefined temperature levels and ranges. A set of reference conditions are defined, and an energy targeting approach is proposed that can be used for characterizing the Theoretical XHT signature, which represents the unavoidable excess heat that can be recovered after maximized internal process heat recovery and ideal integration of a power generation steam cycle. The Theoretical XHT signature is contrasted with the Process Cooling XHT signature, which represents the excess heat that can be recovered given the current design and operation of the process and its utility system. The XHT signature curves provide a consistent representation of the excess heat, enabling comparison between sites and aggregation of results from different case studies.

Evaluating the utilisation of industrial excess heat from an energy systems perspective

“…The targeting procedure is formulated as a linear programming problem following the combined objective of maximum electricity generation and maximum excess heat recovery, given certain constraints representing the assumptions about the level of heat recovery and fuel use. In principle, a steam cycle was integrated between the available high-temperature combustion heat from the recovery boiler and the heat demands of the production process [109]. Figure 5 shows a graphical representation of this integration between the steam cycle, the process and the recovery boiler, in a background/foreground analysis.…”

“…The resulting temperature profile is referred to as the excess heat temperature (XHT) signature, as discussed in detail by Svensson et al [110] and Svensson et al [109]. The assumptions about the integrated steam cycles heavily affect the estimated availability of excess heat from the mills.…”

Potential for Negative Emissions by Carbon Capture and Storage From a Novel Electric Plasma Calcination Process for Pulp and Paper Mills

“…The steam turbine cycle was represented as the foreground GCC. The approach is similar to that described in Svensson et al (2019). The main assumptions and simplifications for this analysis were:…”

Analysis of the performance of direct contact heat exchange systems for application in mine waste heat recovery

“…2 This indispensable reality motivates Industries around the world to adopt renewable sources of energy. [3][4][5][6] In most countries, mining is one of the most energyintensive industries. This is especially true in Canada.…”