Nitrogen return-to-tank device

The utility model discloses a device for returning nitrogen to a tank. The device comprises a material pumping pipe, a gas-solid separator, a dust remover, a vacuum suction machine and a cooler, one end of the material pumping pipe is connected with a feeding port of the gas-solid separator, the other end of the material pumping pipe extends into the reactor, the gas outlet end of the gas-solid separator is connected with the gas inlet end of the dust remover, the gas outlet end of the dust remover is connected with the gas inlet end of the vacuum suction machine, and the gas outlet end of the vacuum suction machine is connected with the gas inlet end of the cooler. According to the utility model, a circulation loop is formed by the gas-solid separator, the dust remover, the vacuum suction machine, the cooler and the reactor, when the waste catalyst in the reactor is sucked and discharged, the catalyst carrying nitrogen can be pumped out under the action of the vacuum suction machine and is separated by the g