The invention relates to an acid-base two-step process
system which comprises a preprocessing
system and is used for preparing
fatty acid methyl ester and
glycerol from kitchen
waste oil. The
system comprises a kitchen
waste oil preprocessing unit, an acid-base two-step esterlysis reaction unit, a
glycerol separation and
recovery unit, a rinsing and dehydrating unit and a decoloration filtering unit and the like. The processes are as follows: step I: after
impurity removal,
dehydration and deodorization are carried out on the kitchen
waste oil, 40% concentrated
sulfuric acid the weight of which is 1-5% of that of the waste oil is added, absolute
methanol is added based on the
alcohol-oil ratio of (6:1)-(9:1), heating is carried out until the temperature is 60-65 DEG C, the mixture is stirred for 1-3 hours at a revolving speed of 200-400r / min, and then rinsing separation and
dehydration are carried out, thus obtaining the
fatty acid methyl ester and crude
glycerol; and step II:
solid base catalyst the
mass percent concentration of which is 0.5-5% is added in the rinsed
fatty acid methyl ester mixture, absolute
methanol is added based on the
alcohol-oil ratio of (3:1)-(6:1), reaction is carried out for 1-3 hours at 20-50 DEG C, and then
distillation is carried out under reduced pressure, thus obtaining the
fatty acid methyl ester.