Raw materials acetaldehyde and cold hydrocyanic acid are continuously fed
into the reactor 1 to generate lactonitrile, and the lactonitrile is fed into the reactor
2 by a pump; Injecting water and sulfuric acid into reactor 2 to hydrolyze
lactonitrile to obtain crude lactic acid and ammonium bisulfate; Pumping the
material flow from the reactor 2 into an esterification tank, adding ethanol into the
esterification tank, carrying out esterification reaction between the ethanol and
crude lactic acid to generate crude ethyl lactate, and separating ammonium
bisulfate; The crude ethyl lactate from the esterification tank is rectified in a first
distillation tower to obtain refined ethyl lactate, then the refined ethyl lactate is
heated and decomposed and sent to a second distillation tower for decomposition,
and dilute lactic acid obtained at the bottom of the tower is evaporated and
concentrated to obtain the product refined lactic acid.
