A Hydrogen Production System Based on Ammonia Combustion Heat: Graded Decomposition and Parameter Analysis

Shijiazhuang Tiedao University, School of Mechanical Engineering, 050043, Shijiazhuang, Hebei, China

^* Corresponding author’s email: liubin@stdu.edu.cn

Abstract

This study introduces a hydrogen production system that utilizes the heat from ammonia combustion for graded decomposition. About 17% of the ammonia undergoes combustion to provide heat for the subsequent decomposition of the remaining ammonia. To enhance economic efficiency and reduce costs, a design combining precious and non-precious metals is employed, aiming to decrease the usage of precious metal catalysts without compromising decomposition efficiency. Considering the required temperatures for the two catalysts, high and low-temperature decomposers are established to achieve cascaded energy utilization in the flue gas. The preheating temperature of ammonia before entering the decomposer plays a crucial role in both ammonia decomposition efficiency and the system’s fuel consumption. Following optimization, the system yields 493.6kg/h of hydrogen with an inlet ammonia flow rate of 4000kg/h. Concurrently, the discharge temperature of the flue gas decreases to 378.59K, effectively utilizing a substantial portion of the energy. This study introduces a novel approach to designing an ammonia decomposition system using ammonia combustion as a heat source, and it serves as a reference for subsequent optimization.