Thermoeconomic assessment of a cement-plant waste-heat-driven trigeneration system for power, cooling, and desalination

• Temperature-cascaded tri-generation system integrates C-ORC, DEAC, and MSF units. • Recovered 514.8 GWh yr⁻¹ of waste heat boosts overall EUF to 0.81. • Provides 2.23 × 10⁶ m³ yr⁻¹ freshwater (∼1.22 m³ t⁻¹ clinker) from low-grade heat. • Cooling subsystem displaces 45.6 GWhₑ yr⁻¹ and avoids ∼41 kt CO₂ yr⁻¹. • Demonstrates an energy–water nexus pathway for decarbonizing cement plants. Cement production is one of the most energy- and carbon-intensive industrial activities, with a large fraction of the fuel input rejected as medium- and low-grade waste heat from cyclone preheaters and clinker coolers. This study proposes and evaluates a waste-heat-driven trigeneration system for a 5,000 t·day⁻¹ dry-process cement plant that simultaneously delivers electricity, process cooling, and desalinated water, thereby addressing coupled energy–water challenges in water-stressed regions. The configuration cascades multi-grade waste heat through three thermally coupled subsystems: (i) a cascade Organic Rankine Cycle (C-ORC) with high- and low-pressure loops matched to the preheater (300–380°C) and clinker-cooler (250–340°C) exhausts, (ii) an internally recuperated double-effect LiBr/H₂O absorption chiller (DEAC), and (iii) a 20-stage brine-recirculation multi-stage flash (MSF) desalination unit fed by a closed hot-water loop with a top-brine temperature of 103°C, below typical CaSO₄/CaCO₃ scaling limits. Aspen Plus V14 simulations show that the preferred C-ORC layout delivers 6.30 MW with an exergy efficiency of 40.66%, while the selected DEAC configuration achieves a coefficient of performance of 1.40 and an exergy efficiency of 43%. The MSF subsystem attains a gained-output ratio of about 7.5–8 and produces 2.23 × 10⁶ m³·y⁻¹ of freshwater at a specific thermal energy consumption of 83.3 kWh·m⁻³. At system level, the integrated C-ORC–DEAC–MSF arrangement recovers 514.78 GWh·y⁻¹ of waste heat, corresponding to 142.88 GWhₑ·y⁻¹ on an electricity-equivalent basis, increases the overall energy utilization factor to 0.81, and avoids 128.6 × 10³ t CO₂·y⁻¹ under standard grid-displacement assumptions. Beyond these plant-scale metrics, the work provides a transferable thermo-economic and environmental assessment framework for waste-heat-driven trigeneration and illustrates the potential of such integrated schemes to co-produce low-carbon power, cooling, and desalinated water in energy- and water-constrained industrial systems.