Objective The LNG regasification process suffers from several limitations, including single-mode cold energy utilization, poor temperature zone matching, severe exergy loss, and low comprehensive utilization efficiency. Developing a cold-electricity-chemical poly-generation system offers a viable strategy for the high-efficiency, cascade utilization of LNG cold energy.

Methods A novel cold-electricity-chemical poly-generation system is proposed in this study. By integrating a two-stage Rankine cycle with the Methanol to Propylene (MTP) process, a three-stage cold energy cascade utilization framework is established, comprising cryogenic power generation, medium-cold power generation and mild-cold chemical production. This framework enables the precise matching of wide-temperature-range LNG cold energy with the heat-transfer demands of the chemical processes. At the methodological level, pinch analysis is applied to perform heat integration across the global heat exchange network. With the minimum temperature approach (ΔT_min = 20 °C) designated as the core design parameter, an optimized heat exchange network configuration with superior relative thermal economy is determined. Furthermore, exergy analysis is introduced to map the distribution of internal irreversible losses within the system. Finally, an economic evaluation model is developed based on the incremental investment-incremental benefit principle, and single-factor sensitivity analysis together with Monte Carlo simulation are combined to quantify project risks.

Results The exergy efficiency of LNG cold energy is increased from 4.99％ in the traditional power-only scheme to 19.35％. Through the three-stage framework, cascade transmission of cold energy is achieved within the optimized heat exchange network. The system delivers a net power output of 1 342 kW and supplies 9 663 kW of cooling duty to the MTP process, equivalent to a power saving of 3 865 kW. Economic evaluation of the retrofit scenario indicates an incremental fixed asset investment of RMB 4 962×10⁴, yielding an annual net cash flow of RMB 2 045×10⁴. The Net Present Value (NPV) reaches RMB 12 540×10⁴, with an Internal Rate of Return (IRR) of 41％, a dynamic payback period of 3.8 years, and a levelized energy cost of RMB 0.161/(kW·h), demonstrating highly favorable economic indicators. Furthermore, uncertainty analysis reveals no instances of a negative NPV across 10 000 Monte Carlo samples. Even under the worst 5％ of simulated scenarios, the NPV remains above RMB 8 946×10⁴, reflecting robust risk resistance.

Conclusion The established comprehensive analysis framework—spanning thermodynamic cascade design, system integration optimization, and economic risk assessment—verifies the technical and economic viability of the cold-electricity-chemical poly-generation mode in maximizing LNG cold energy utilization efficiency and economic value. The research findings provide a replicable design paradigm for upgrading LNG cold energy cascade utilization systems.