In the context of “carbon peak” and “carbon neutrality”

using renewable electricity to electrolyze water to produce hydrogen and synthesize ammonia can not only consume renewable energy and solve the problem of hydrogen storage and transportation

but also promote the green transformation of the conventional ammonia synthesis process. To investigate the effect of different hydrogen production schemes on technical and economic performance of the synthetic ammonia system

the system thermal and economic performance of three hydrogen production schemes

including proton exchange membrane electrolyzer hydrogen production

proton exchange membrane electrolyzer and alkaline water electrolyzer hydrogen production in a 1:1 ratio

and alkaline water electrolyzer hydrogen production

are compared and analyzed. The hot and cold integration of the synthetic ammonia system with coordinated hydrogen production by proton exchange membrane electrolyzer and alkaline water electrolyzer is analyzed by combining pinch analysis with mathematical programming. The results show that

the system exergy efficiencies of the above three hydrogen production schemes are 60.3%

56.1% and 52.5%

respectively

and the carbon emissions of ammonia also increase due to the increase in net power consumption of the system. Benefiting from alkaline water electrolyzer's mature hydrogen production process

the alkaline water electrolyzer hydrogen production scheme has the shortest investment payback period of 6.4 years

while the proton exchange membrane electrolyzer hydrogen production scheme has the longest investment payback period of 12.8 years. The thermal integration analysis of the synthetic ammonia system for the coordinated hydrogen production of proton exchange membrane electrolyzer and alkaline water electrolyzer shows that the low-temperature waste heat below 100 ℃ in the system is released to the environment via cold utilities. In addition

increasing the operating temperature of the electrolyzer is beneficial to improving thermal performance of the system

while lowering electricity price and increasing the annual operating hours of the system will help to improve the economic performance of the system.