The capacity of a fully premixed low-nitrogen steam generator, i.e., the evaporation capacity of the boiler, refers to the amount of steam produced per hour by the steam boiler, measured in t/h (or g/s). In large steam boilers, capacity is further divided into rated evaporation capacity and maximum continuous evaporation capacity.

The rated evaporation capacity of a fully premixed low-nitrogen steam generator refers to the specified evaporation capacity under rated steam parameters, rated feedwater temperature, and using design fuel, while ensuring thermal efficiency. The maximum continuous evaporation capacity of a steam boiler refers to the maximum evaporation capacity achievable during long-term operation under rated steam parameters, rated feedwater temperature, and using design fuel.

The rated steam parameters for the rated evaporation capacity of a fully premixed low-nitrogen steam generator refer to the rated steam pressure and rated steam temperature. Rated steam pressure refers to the outlet steam pressure that must be guaranteed during long-term operation of the steam boiler under specified feedwater pressure and within the specified load range, measured in MPa.

Rated steam temperature refers to the outlet steam temperature that must be guaranteed during long-term continuous operation of the steam boiler within the specified load range, under rated steam pressure and rated feedwater temperature, measured in degrees Celsius. In modern power station boilers equipped with reheaters, the steam parameters of the steam boiler include not only the rated superheated steam parameters but also the rated reheat steam parameters.