Alkylene oxide separation system

A method comprising:

• (i) subjecting a crude propylene oxide stream to non-solvent distillation in a heavies distillation column to produce a heavies purge bottoms comprising at least one impurity selected from acetone, methanol, aldehydes, aldehyde derivatives, water, heavy hydrocarbons comprising C5+, or combinations thereof, and a heavies distillation column overhead stream comprising a majority of the propylene oxide entering in the crude propylene oxide stream;
• (ii) introducing the heavies distillation column overhead stream and a first extractive distillation solvent stream comprising a hydrocarbon solvent into a first extractive distillation column to produce a lights purge overhead comprising at least one impurity selected from acetaldehyde, methyl formate, methanol, water, C3 hydrocarbons, C4 hydrocarbons, or combinations thereof, and a rich solvent bottoms stream comprising a majority of the propylene oxide entering via the heavies distillation column overhead stream;
• (iii) introducing a side draw from the first extractive distillation column into a decanting apparatus, and therein allowing the formation of an aqueous phase purge comprising water and methanol, one or more glycols, or a combination thereof, and an organic phase stream comprising propylene oxide and the hydrocarbon solvent;
• and
• (iv) introducing the rich solvent bottoms stream from the first extractive distillation column into a first solvent stripper to produce a first solvent stripper overhead comprising a majority of the propylene oxide entering the first solvent stripper via the rich solvent bottoms stream and a first solvent stripper bottoms comprising lean hydrocarbon solvent.

A method comprising:

• (i) subjecting a crude propylene oxide stream to non-solvent distillation in a heavies distillation column to produce a heavies purge bottoms comprising at least one impurity selected from acetone, methanol, aldehydes, aldehyde derivatives, water, heavy hydrocarbons comprising C5+, or combinations thereof, and a heavies distillation column overhead stream comprising a majority of the propylene oxide entering in the crude propylene oxide stream;
• (ii) introducing the heavies distillation column overhead stream and a first extractive distillation solvent stream comprising a hydrocarbon solvent into a first extractive distillation column to produce a lights purge overhead comprising at least one impurity selected from acetaldehyde, methyl formate, methanol, water, C3 hydrocarbons, C4 hydrocarbons, or combinations thereof, and a rich solvent bottoms stream comprising a majority of the propylene oxide entering via the heavies distillation column overhead stream;
• (iii) introducing at least a portion of the lights purge overhead from the first extractive distillation column into a decanting apparatus, and therein allowing the formation of an aqueous phase purge comprising water and methanol, one or more glycols, or a combination thereof, and an organic phase stream comprising propylene oxide and the hydrocarbon solvent;
• and
• (iv) introducing the rich solvent bottoms stream from the first extractive distillation column into a first solvent stripper to produce a first solvent stripper overhead comprising a majority of the propylene oxide entering the first solvent stripper via the rich solvent bottoms stream and a first solvent stripper bottoms comprising lean hydrocarbon solvent.