A propylene oxide separation system comprising a heavies distillation column configured to receive a crude propylene oxide stream and discharge a heavies purge bottoms comprising at least one impurity selected from acetone, methanol, aldehydes, aldehyde derivatives, water, heavy hydrocarbons comprising C.sub.5+, or combinations thereof, and discharge a heavies distillation column overhead stream comprising a majority of the propylene oxide entering with the crude propylene oxide stream, and a first extractive distillation column configured to receive the heavies distillation column overhead stream and a first extraction solvent stream comprising a hydrocarbon solvent, and discharge a lights purge overhead comprising at least one impurity selected from aldehydes (e.g., acetaldehyde, formaldehyde, etc.) methyl formate, methanol, water, C.sub.3 hydrocarbons, C.sub.4 hydrocarbons, or combinations thereof, and discharge a rich solvent bottoms stream comprising a majority of the propylene oxide entering via the heavies distillation column overhead stream. A propylene oxide purification method is also provided.

A propylene oxide separation system comprising a heavies distillation column configured to receive a crude propylene oxide stream and discharge a heavies purge bottoms comprising at least one impurity selected from acetone, methanol, aldehydes, aldehyde derivatives, water, heavy hydrocarbons comprising C.sub.5+, or combinations thereof, and discharge a heavies distillation column overhead stream comprising a majority of the propylene oxide entering with the crude propylene oxide stream, and a first extractive distillation column configured to receive the heavies distillation column overhead stream and a first extraction solvent stream comprising a hydrocarbon solvent, and discharge a lights purge overhead comprising at least one impurity selected from aldehydes (e.g., acetaldehyde, formaldehyde, etc.) methyl formate, methanol, water, C.sub.3 hydrocarbons, C.sub.4 hydrocarbons, or combinations thereof, and discharge a rich solvent bottoms stream comprising a majority of the propylene oxide entering via the heavies distillation column overhead stream. A propylene oxide purification method is also provided.

Systems and processes for heat recovery associated with the separation of hydrocarbon components. Two compressors are used to compress a portion of an overhead vapor stream from a fractionation column. A pressure of the liquid portion of the compressed overhead is reduced and used to recover heat from an overhead of another separation zone having a fractionation column. Once the heat has been recovered the stream is recompressed. The recovered heat may be removed from the recompressed stream in a reboiler of another fractionation column. The fractionation columns may comprise a deethanizer stripper, propane-propylene splitter, and a depropanizer column.

The invention relates to an improved process for providing purified styrenic monomers, such as styrene, from styrene-containing polymer waste. Styrene-containing waste is depolymerized in a suitable reactor, and the depolymerization products are condensed and separated in a three-step distillation process.

Systems and processes for heat recovery associated with the separation of hydrocarbon components. Two compressors are used to compress a portion of an overhead vapor stream from a fractionation column. A pressure of the liquid portion of the compressed overhead is reduced and used to recover heat from an overhead of another separation zone having a fractionation column. Once the heat has been recovered the stream is recompressed. The recovered heat may be removed from the recompressed stream in a reboiler of another fractionation column. The fractionation columns may comprise a deethanizer stripper, propane-propylene splitter, and a depropanizer column.

The object of the present invention is to provide a stable isotope concentration method that reduces equipment cost and power without prolonging the start-up time and enables efficient concentration, and the present invention provides a stable isotope concentration method using multiple cascaded distillation columns (1st column to mth column; m is an integer of 2 or more), wherein the method includes a step in which one of gas and liquid is supplied from a position in the vicinity of the bottom of a (n1)th column to a position in the vicinity of the top of an nth column (1<nm), and the other of liquid and gas is returned from a position in the vicinity of the top of the nth column to a position in the vicinity of the bottom of the (n1)th column; and wherein in each distillation column, when a flow rate of an ascending gas in the column is a first flow rate and a flow rate of the gas or the liquid supplied from a previous column or a next column is a second flow rate, the second flow rate is 4% by volume or more with respect to the first flow rate.

A separation device including a cylindrical column; a plurality of dual flow trays provided inside the cylindrical column to partition a plurality of stages; and a feed supply unit provided in one of the plurality of stages to supply a raw material including a liquid reactive monomer, in which a structure of the feed supply unit is designed so that feed can be uniformly distributed inside the column, thereby improving column efficiency. The feed supply unit can include a circular feed transfer pipe spaced apart between a lower and an upper dual flow tray of the stage in which the feed supply unit is provided, a plurality of inner pipes extending in a direction of a central axis from the feed transfer pipe, and a plurality of spray nozzles, where each of the plurality of inner pipes is individually provided with a plurality of the spray nozzles.