Pinch
Analysis

Apply the cascade algorithm to calculate thermodynamically rigorous minimum heating and cooling utility targets. This step reveals the theoretical best-case energy performance for your process.

Using the validated stream data, we construct temperature interval diagrams and run the heat cascade to pinpoint the exact pinch temperature and quantify the minimum hot and cold utility demands. The results establish an absolute benchmark against which the current utility consumption is compared, immediately highlighting the energy saving potential. A sensitivity analysis on the minimum approach temperature (ΔTmin) is performed to understand how target values shift with exchanger sizing.

Construct temperature-enthalpy composite curves that graphically reveal the maximum recoverable heat and the driving forces available across the process. These curves are the central diagnostic tool in pinch analysis.

Hot and cold streams are aggregated into composite profiles and plotted on a temperature-enthalpy diagram, making it straightforward to visualise the overlap region where process-to-process heat exchange is thermodynamically feasible. The gap between the curves at the pinch defines the minimum approach temperature, while the non-overlapping tails quantify the irreducible utility demands. This graphical output is a powerful communication tool for stakeholders, translating complex thermodynamic data into an intuitive visual.

Generate the grand composite curve to identify the optimal temperature levels at which utilities should be supplied and to reveal pockets of heat surplus or deficit. This guides the selection of steam grades, hot oil circuits, and cooling water tiers.

The grand composite curve plots net enthalpy deficit against shifted temperature, exposing where high-grade utilities can be replaced by lower-cost alternatives such as low-pressure steam or waste heat sources. It also highlights opportunities for heat pump placement, process integration across different pressure levels, and cascading of rejected heat. The result is a utility strategy that minimises both energy cost and exergy destruction across the plant.

Synthesise a heat exchanger network that achieves maximum energy recovery by rigorously applying the pinch design rules. The resulting network captures all thermodynamically feasible heat exchange between process streams.

Starting from the pinch point, matches are made separately above and below the pinch to ensure no cross-pinch heat transfer, no external cooling above the pinch, and no external heating below it. Each match specifies exchanger duty, inlet/outlet temperatures, and required surface area using appropriate correlations for shell-and-tube, plate, or compact exchanger geometries. The initial MER design serves as the theoretical benchmark from which practical network simplification and costing proceed.

Evolve the MER network into a practical, cost-effective design by relaxing constraints and reducing the number of exchanger units. This step balances thermodynamic ideality with real-world capital and operability considerations.

Small-duty exchangers and loop-breaking strategies are evaluated to reduce the total number of units while keeping the energy penalty within acceptable limits. Heat load paths are re-routed using energy relaxation techniques, and split-stream fractions are adjusted to improve controllability and reduce piping complexity. The outcome is a streamlined network with fewer units, lower capital expenditure, and a clear understanding of the marginal energy cost of each simplification.

Evaluate the integration of combined heat and power, heat pumps, absorption chillers, and other utility technologies to further reduce primary energy consumption. Placement is guided by the grand composite curve to ensure thermodynamic and economic viability.

CHP systems are sized and placed so that shaft power is generated from the temperature difference between high-grade heat supply and the process pinch, maximising cogeneration efficiency. Heat pumps are assessed across the pinch where the temperature lift is modest enough to deliver a favourable coefficient of performance, and absorption refrigeration cycles are considered where sub-ambient cooling is required. Each option is benchmarked against conventional utility supply to quantify carbon, cost, and reliability impacts.