Continuous purification process for nickel sulfate solution

The invention provides a continuous purification process for a nickel sulfate solution. The continuous purification process comprises the following steps: preheating the nickel sulfate solution; evaporating and concentrating the preheated feed liquid, and transferring the evaporated and concentrated feed liquid into a crystallizing tank; the evaporated secondary steam is recycled after the enthalpy is increased through a steam compressor, and flash evaporation condensate water of the crystallizing tank enters a dissolving device to be recycled as material liquid preparation; pumping crystal slurry separated out from the crystallizing tank to a thickener, dehydrating the thickened slurry in a centrifugal machine, discharging one part of supernatant mother liquor, returning the other part of supernatant mother liquor and centrifugal mother liquor to a raw material barrel, feeding wet solid discharged from the centrifugal machine from the top of a dissolving device, calculating the water adding amount according