Full-load denitration operation control method for natural circulation coal-fired unit

The invention discloses a method for realizing full-load denitration operation control of a natural circulation coal-fired unit, which comprises the following steps of: (1) after a boiler is ignited, increasing the coal quantity, intensifying combustion, increasing the temperature of boiler water in a steam pocket and increasing the temperature of water in a coal economizer by utilizing a coal economizer recirculation pipe and a coal economizer recirculation door; (2) when the unit is started until the steam turbine rotates, the water temperature of a deaerator is increased, and the steam turbine is subjected to double-section type warming-up, so that the water inlet temperature of the economizer is increased, and smoke heat absorbed by the economizer is reduced; and (3) before the unit is prepared to be connected to a grid, boiler combustion adjustment and optimization are carried out, specifically, an upper-layer coal mill is additionally arranged, pulverized coal milled by the additionally arranged upper-l