Refrigeration control

Claim 2

A process for cooling a first fluid stream with a second fluid stream which comprises: cooling said first stream by passage through a first heat exchange zone; measuring the temperature of said first stream after passing through said first heat exchange zone; cooling said first stream further by passage through a second heat exchange zone; heating a first part of said second fluid stream by passage through said second heat exchange zone while passing a second part of said second fluid stream through a bypass zone around said second heat exchange zone; heating said second part of said second fluid stream by passage through said first heat exchange zone; and controlling the flow of said first and second parts of said second fluid stream in response to the measured temperature of said first stream.

Claim 3

The process of claim 1 wherein said first part of said second fluid stream after passing through said second heat exchange zone is passed through at least a portion of said first heat exchange zone.

Claim 4

The process of claim 2 wherein said first part of said second fluid stream after passage through said second heat exchange zone is combined with said second part of said second fluid stream prior to passage of said second part of said second fluid stream through said first heat exchange zone.

Claim 5

The process of claim 1 wherein said first part of said second fluid stream bypasses said first heat exchange zone.

Claim 6

The process of claim 1 wherein said first stream is a gas containing water vapor and the passage of said first stream through said first heat exchange zone condenses a portion of said water vapor; wherein said condensed water vapor is separated from said first stream; wherein the remainder of said first stream is further cooled in said second cooling zone; and wherein the flow of said first and second parts of said second fluid stream is controlled to maximize the condensation of water vapor from said first stream in said first heat exchange zone while avoiding hydrate formation.

Claim 7

The process of claim 5 further comprising adding a hydrate inhibitor to the remainder of said first stream prior to passage through said second heat exchange zone.

Claim 8

The process of claim 5 wherein said first part of said second fluid stream after passing through said second heat exchange zone is passed through at least a portion of said first heat exchange zone.

Claim 9

The process of claim 5 wherein said gas containing water vapor in said first stream is natural gas containing at least one condensible hydrocarbon; wherein a hydrate inhibitor is added to the remainder of said first stream after removal of the condensed water vapor and prior to being cooled in said second cooling zone; wherein a second amount of hydrate inhibitor is added to the remainder of said gas stream after said gas stream is cooled in said second heat exchange zone; wherein the remainder of said gas stream is further cooled by passage through a third heat exchange zone in countercurrent heat exchange flow with a cold refrigerant thereby condensing at least a portion of said condensible hydrocarbon; wherein the condensed condensible hydrocarbon is separated from said gas stream to produce a liquid hydrocarbon stream and a residue gas stream; and wherein said second fluid stream is said residue gas.

Claim 10

The process of claim 8 wherein said first part of said second fluid stream after passing though said second heat exchange zone is passed through at least a portion of said first heat exchange zone.

Claim 11

The process of claim 9 wherein said hydrate inhibitor component is ethylene glycol.

Claim 12

Apparatus for cooling a first fluid stream with a second fluid stream which comprises: a first heat exchanger; means for passing a first fluid stream through said first heat exchanger; means to measure the temperature of said first stream after passing through said first heat exchanger; a second heat exchanger; means to pass said first stream through said second heat exchanger for further cooling; means to pass a first part of a second fluid stream through said second heat exchanger in heat exchange relation with said first fluid stream; means to pass a second part of said second fluid stream through a bypass around said second heat exchanger and then through said first heat exchanger in heat exchange relation with said first stream; and means to control the flow of said first and second parts of said second fluid stream in response to the measured temperature of said first fluid stream.

Claim 13

Apparatus for cooling a first fluid stream with a second fluid stream which comprises: a first heat exchanger; means for passing a first fluid stream through said first heat exchanger; means to measure the temperature of said first stream after passing through said first heat exchanger; a second heat exchanger; means to pass said first stream through said second heat exchanger for further cooling; means to pass a first part of a second fluid stream through said second heat exchanger in heat exchange relation with said first fluid stream; means to pass a second part of said second fluid stream through a bypass around said second heat exchanger and then through said first heat exchanger in heat exchange relation with said first stream; and means to control the flow of said first and second parts of said second fluid stream in response to the measured temperature of said first fluid stream.

Claim 14

The apparatus of claim 11 wherein said first fluid stream is a natural gas stream containing water vapor and said second fluid stream is a residue gas stream; wherein said apparatus comprises means to separate condensed water vapor from said natural gas stream after leaving said first heat exchanger; means to add a hydrate inhibitor to said natural gas stream after separation of said condensed water vapor and prior to passage of said stream through said second heat exchanger; means for adding a second amount of hydrate inhibitor to said natural gas stream after leaving said second heat exchanger; a third heat exchanger; means to pass said natural gas stream containing said second amount of hydrate inhibitor through said third heat exchanger; means to pass a cold refrigerant through said third heat exchanger in heat exchange relation with said natural gas stream to condense at least a portion thereof; and means to separate said natural gas stream after leaving said third heat exchanger to produce a liquid hydrocarbon stream and said residue gas stream.