The present invention discloses a method for producing isopropanolamine by using a fixed bed tubular reactor. The method comprises: by using water as a catalyst, putting
ammonia and
epoxy propane with a
molar ratio of (3.5-15):1 into a
fixed bed reactor to perform a reaction, wherein the operation pressure of the reactor is 8-25 MPa, and the
operation temperature is 160-220 DEG C; pumping a
reaction product sequentially into a first
flash evaporation tank and a second
flash evaporation tank, performing two-stage
flash evaporation and
ammonia removal on the
reaction product, and then introducing the processed
reaction product into a
dehydration tower for primary
dehydration; introducing
dehydration materials at the bottom of the dehydration
tower into a
monoisopropanolamine rectification
tower, introducing discharged materials at the top of the
monoisopropanolamine rectification tower into a
monoisopropanolamine conversion reactor, and returning the materials to the bottom of the monoisopropanolamine rectification tower after reaction; introducing discharged materials at the top of the monoisopropanolamine rectification tower into a
diisopropanolamine rectification tower, and after low pressure rectification, obtaining
diisopropanolamine at the top of the
diisopropanolamine rectification tower, and obtaining
triisopropanolamine at the bottom of the diisopropanolamine rectification tower. The method provided by the present invention is capable of reducing the
energy consumption of the whole process, effectively avoids reaction and
side product generation, and improves the product purity.