Crude MDI storage tank and storage method

The invention relates to a crude MDI storage tank and a storage method. The crude MDI storage tank comprises a tank body, a treatment device, a temperature sensor, a circulating pipeline, a pressure sensor, a nitrogen compensation assembly and a tail gas treatment assembly. The processing device comprises a first processing unit and a second processing unit; the first processing unit is used for controlling the nitrogen compensation assembly to conduct nitrogen compensation on the interior of the tank body when the pressure sensor detects that the pressure in the tank body is smaller than a first pressure threshold value. When the pressure sensor detects that the internal pressure of the tank body is greater than a second pressure threshold value, the tail gas treatment rate of the tail gas treatment assembly to the crude MDI is increased; the second processing unit is used for opening the circulation pipeline when the temperature sensor detects that the temperature of the coarse MDI is lower than a first tem