Comparative analysis of a dual Kalina cycle configuration for heat recovery from boiler stack in a steam power plant

This study proposes a dual configuration of the Kalina cycle for heat recovery from a boiler stack in a steam power plant, consisting of two basic Kalina cycles; a top and a bottom one. Thermoeconomic modeling was done using mass and energy balance and economic parameters such as internal rate of return (IRR) and net present value (NPV). The proposed configuration was evaluated by comparing it with the basic Kalina cycle (KSC1) and other modified Kalina cycles configurations KSC11, KSC34, and KSC34G. The flue gas from the stack of the steam boiler (Tarasht Steam Power Plant-Tehran-Iran), a stable low-temperature heat source, was used in the analysis. The temperature range of the heat source, between 172°C and 190°C, was obtained from operational data of the steam power plant, collected for 5 years, using temperature sensors in the exhaust of the stack. The results show that the proposed configuration's output power varies from 591.74 to 755.74 kW and 6.2%–11.2% more than the KSC34 configuration. Accordingly, the thermal efficiency is about 4.56%–6.25% higher than the other studied configurations, and the natural gas saved is 0.7765 to 1.02 Mm3.year−1. Also, the results indicate that the reduction in CO2 emission for the proposed configuration is about 2786–3661 tons.year−1, which is more than the other configurations. © 2022 American Institute of Chemical Engineers.