Coupling of a novel boron-based thermochemical cycle with chemical looping combustion to produce ammonia and power. (18th August 2021)

• Record Type: Journal Article
• Authors: Mohamed, Amro M.O.; Bicer, Yusuf
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 57(2021)
• Page Start: 28949
• Page End: 28960
• Publication Date: 2021-08-18
• Subjects: Chemical looping -- Thermochemical cycle -- Methane decomposition -- Ammonia -- Life cycle assessment -- Exergy; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2020.11.182
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In this work, a novel thermochemical cycle (Boron-based) to produce ammonia is coupled with chemical looping combustion (CLC) process to produce final primary products of ammonia, CO2, water, and electricity. Manganese oxide-based CLC provides high purity N2, water and thermal energy for the carbothermal reduction of liquefied natural gas (LNG) occurring at 1200 °C. Gaseous synthesis gas from the carbothermal reduction is used as a fuel in the CLC's fuel reactor. Ammonia is produced through the hydrolysis of boron nitride (BN) and liquefied at atmospheric pressure. Thermodynamic equilibrium computations are used to predict the conversions of reactions involved in this proposed system. The overall system is then evaluated from energetic and exergetic perspectives to reflect upon the efficiency of reactors and subsystems. The production of approximately 25 metric t/h of NH3 is achieved while power production reaches 232 MW. The exergetic efficiency of the overall system is calculated to be 53.8%. Moreover, life cycle assessments are performed to assess boron oxide environmental impacts and evaluated the exergy-based allocation of greenhouse gases emission to ammonia at 0.772 kg CO2 (eq.)/kg NH3 . About 61% reduction in emissions relative to the global average of ammonia synthesis is estimated. Highlights: New B2 O3 /BN CL cycle is proposed and coupled with an Mn-oxide CLC. The exergy efficiency of the system is 53.8%, electricity production reaches 232 MW. Production of 600 metric t/d of ammonia is obtained while inherently capture CO2 . Energy efficiency of the system is maximized through heat integration and recovery. Environmental burden exergy-based allocated to ammonia is 0.772 kg CO2 (eq.)/kg NH3 .