Effect of Ammonia Co-Firing on Heat Transfer, Safety, and Economy of Coal-Fired Boilers

•Thermodynamic calculation model of a 600 MW boiler co-firing coal and NH3 was established.•Co-firing NH3 decreased furnace heat load but hardly changed flue gas temperature at furnace outlet.•Co-firing NH3 raised the exhaust flue gas temperature and decreased boiler efficiency.•Heat absorption of steam can be satisfied with no modifications of heating surfaces.•Tube wall temperatures of superheaters were changed little by NH3 co-firing.