A natural gas-based eco-friendly polygeneration system including gas turbine, sorption-enhanced steam methane reforming, absorption chiller and flue gas CO2 capture unit

Abstract

Poly-generation systems have attracted a lot of attention due to the increment of efficiency as well as reducing energy penalties, costs and pollutants. Extensive research has been done on these systems in recent years. The current work is done with the aim of simulating an environmentally friendly poly-generation system in the power plant of Shahrood city in Iran. In this way, a poly-generation system is simulated in Aspen Plus software which consists of: I) a gas turbine (GT) for power generation with natural gas fuel of Shahroud power plant, that its flue gas is utilized to supply heat for other cycles and streams, II) a sorption-enhanced chemical looping reforming (SECLR) which simultaneously generates H2 by steam methane reforming (SMR) and uptakes produced CO2 by calcium adsorbent during the carbonation/calcination reactions. In this section, there is also a chemical looping combustion (CLC) based on redox reactions of Ni/NiO to provide heat of the reactors, III) a NH3/H2O absorption refrigeration system to yield the cooling demand, IV) a high-pressure steam generation unit and V) a MEA-based post-combustion CO2 capture unit (PCC) for flue gas. In this system, an attempt has been made to prevent heat loss by internal streams, especially gas turbine exhaust gas, so that energy loss is minimized. Moreover, environmental issues are also prioritized to reduce the CO2 emissions as much as possible. The proposed process is capable of producing 133.3 MW power, 9.875 MW cooling, 50 kg/s high-pressure steam and 0.384 kg/s hydrogen. The mass flow rates of CO2 captured in the SECLR and PCC sections are 2.6 kg/s and 15.35 kg/s, respectively. Moreover, the total energy efficiency of the integrated system is 68.74%. Ultimately, a sensitivity analysis was performed to identify the key parameters and their influence on the process performance.