Systems and Methods for Deep Crystallization of Xylene Streams
AssigneeExxonMobil Chemical Patents Inc.
InventorRobert G. Tinger
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Abstract
Methods for the production of para-xylene include flowing a xylenes-containing stream comprising PX, meta-xylene (MX), and ortho-xylene (OX), to a first crystallization stage. In addition, the methods include lowering a temperature of the xylenes-containing stream to below the eutectic point of the xylenes-containing stream within the first crystallization stage to crystallize at least some of the PX and at least some of one of both of the MX and the OX within the xylenes-containing stream. Further, the methods include separating the xylenes-containing stream into a first crystallization effluent stream and a first filtrate stream.
Claims20
A process, comprising:
- (a) flowing a xylenes-containing stream comprising para-xylene (PX), meta-xylene (MX), and ortho-xylene (OX), to a first crystallization stage;
- (b) lowering a temperature of the xylenes-containing stream to 10° F. or more below the eutectic point of the xylenes-containing stream within the first crystallization stage to crystallize at least some of the PX and at least some of one of both of the MX and the OX within the xylenes-containing stream;
- and
- (c) separating the xylenes-containing stream into a first crystallization effluent stream and a first filtrate stream after (b).
A process, comprising:
- (a) flowing a feed stream to a separation tower;
- (b) separating a xylenes-containing stream from the feed stream within the separation tower, wherein the xylenes-containing stream comprises para-xylene (PX), meta-xylene (MX), and ortho-xylene (OX);
- (c) flowing the xylenes-containing stream to a first crystallization stage;
- (d) lowering a temperature of the xylenes-containing stream to −100° F. (−73.33° C.) or lower within the first crystallization stage to crystallize at least some of the PX and at least some of one of both of the MX and the OX within the xylenes-containing stream;
- (e) separating the xylenes-containing stream into a first crystallization effluent stream and a first filtrate stream after (d);
- (f) flowing the first crystallization stage effluent stream to a second crystallization stage after (e);
- (g) changing the temperature of the first crystallization stage effluent stream within the second crystallization stage to above approximately −90° F. (−67.8° C.);
- (h) separating the first crystallization stage effluent stream into a second crystallization stage effluent stream and a second filtrate stream after (g);
- (i) flowing the second filtrate stream to a first liquid phase isomerization unit to produce a first isomerized stream;
- and
- (j) recycling the first isomerized stream to at least one of:
- the first crystallization stage;
- or
- the second crystallization stage.
Dependencies are inferred from the claim text.