Safety protection system and safety protection method for floating-roof oil tank based on active nitrogen filling

Disclosed is a fire safety protection system for a floating-roof oil tank based on active nitrogen filling. At least one gas partition plate is arranged between a primary sealing section and a secondary sealing section of the floating-roof oil tank, a gas inlet pipe and a gas outlet pipe are arranged in a matched manner, the gas inlet pipe is fixedly mounted at the sealing edge of the oil tank and connected with a gas nozzle which is a double-layer disc gas nozzle, a gas pump is connected with the gas outlet pipe, and an optical fiber pressure sensor, an optical fiber temperature sensor, a sensing signal processing unit, the gas pump, a gas detection module, a gas valve controller and a nitrogen fire protection controller are arranged outside the floating-roof oil tank. When fire-breeding is discovered or other areas on site have a fire, nitrogen is rapidly released, a protection layer is formed above the oil tank to realize fire protection, and a closed-loop control is formed by the aid of the gas partition plates and by means of pressure and temperature detection and active combustible gas suction detection. When abnormal temperature, pressure and oil and gas leakage are discovered, protection gas is filled, fire risks are reduced, and the safety performance of the oil tank is improved.