Nitrogen dioxide preparation device and preparation method

The invention discloses a nitrogen dioxide preparation device and a preparation method, belongs to the technical field of chemical engineering, and aims to improve the quality of nitrogen dioxide gas and reduce the content of sodium nitrite in byproducts. Comprising a sodium nitrite feeding tank and a heater I, the device comprises a dilute nitric acid feeding tank, a generator, a mixer, a separator and an oxidation system, a liquid outlet of the acid feeding tank is communicated with a nitric acid liquid outlet main path, is communicated with a liquid removal section of the generator through a nitric acid liquid outlet branch I, is converged with a sodium nitrite liquid outlet pipeline through a nitric acid liquid outlet branch II, and is connected to a reaction section in the middle of the generator through a mixer; a top gas outlet of the generator is communicated with a gas inlet of the separator; a gas outlet of the separator is communicated with the oxidation system; and a bottom liquid outlet of the ge