Treatment method and system for heavy oil in production of maleic anhydride by n-butane method

The invention discloses a treatment method and system for heavy oil in production of maleic anhydride by an n-butane method. The treatment method comprises the following steps: S1) setting a temperature threshold value of a solvent flash evaporation thermometer; s2) conveying the mixed solvent into a solvent heater for heating; s3) if a threshold value set by the solvent flash evaporation thermometer is reached, entering step S4), otherwise, returning to step S2); s4, the solvent reaching the set temperature threshold value enters a flash tank, a half-pipe heat tracing device outside the flash tank is started for heating, it is guaranteed that the temperature is not lower than 140 DEG C, the absolute pressure in the flash tank ranges from 1 kPa to 20 kPa, and gas stripping is conducted; according to the device, the solvent cannot be decomposed to generate additional phthalic anhydride and butanol, nitrogen gas stripping is adopted, separation of the light solvent and heavy oil is accelerated, and the content