US4854954A — Rectifier liquid generated intermediate reflux fo…

Claim 1

Independent Claim 133 words

In a process for the subambient temperature fractional distillation of a fluid mixture comprising rectifying at least part of the feed at high pressure, distilling the rectified feed at a lower pressure, reboiling said distilling step by exchanging latent heat with vapor from said rectifiying step, and refluxing said distilling step with depressurized liquid from said latent heat exchanging step, the improvement comprising: (a) essentially totally condensing a minor fraction of the feed, which is preferably at a pressure at least as high as the pressure of said rectifying step, by exchanging latent heat with a liquid from said rectifying step; (b) splitting the condensed feed into at least two streams; and (c) intermediate refluxing said high pressure rectifying step with one of said streams and said low pressure distilling step with another.

Claim 2

Dependent Claim 133 words

In a process for the subambient temperature fractional distillation of a fluid mixture comprising rectifying at least part of the feed at high pressure, distilling the rectified feed at a lower pressure, reboiling said distilling step by exchanging latent heat with vapor from said rectifiying step, and refluxing said distilling step with depressurized liquid from said latent heat exchanging step, the improvement comprising: (a) essentially totally condensing a minor fraction of the feed, which is preferably at a pressure at least as high as the pressure of said rectifying step, by exchanging latent heat with a liquid from said rectifying step; (b) splitting the condensed feed into at least two streams; and (c) intermediate refluxing said high pressure rectifying step with one of said streams and said low pressure distilling step with another.

Claim 3

Dependent Claim 49 words

Process according to claim 1 additionally comprising controlling the amount of feed totally condensed, and controlling split proportions of said condensed feed, so as to achieve a pinch condition at the intermediate reflux height and at least one feed height of both said rectifying step and said distilling step.

Claim 4

Dependent Claim 22 words

Process according to claim 1 additionally comprising increasing the pressure of said minor fraction of feed prior to said total condensing step.

Claim 5

Dependent Claim 37 words

Process according to claim 3 additionally comprising work-expanding at least part of one of the vapor streams associated with said distillation process, and applying the work generated thereby to power at least part of said pressure-increasing step.

Claim 6

Dependent Claim 15 words

Process according to claim 1 wherein said liquid from said rectifying step is overhead liquid.

Claim 7

Dependent Claim 36 words

Process according to claim 5 additionally comprising reducing the pressure of said overhead liquid and work-expanding said minor fraction of feed prior to said latent heat exchanging step between totally condensing feed and evaporating overhead liquid.

Claim 8

Dependent Claim 39 words

Process according to claim 5 additionally comprising increasing the pressure of said overhead liquid and increasing the pressure of said minor fraction of feed prior to said latent heat exchanging step between totally condensing feed and evaporating overhead liquid.

Claim 9

Dependent Claim 15 words

Process according to claim 1 wherein said liquid from said rectifying step is bottom liquid.

Claim 10

Dependent Claim 34 words

Process according to claim 8 additionally comprising reducing the pressure of said bottom liquid prior to said latent heat exchanging step with condensing feed; and work-expanding the resulting evaporated portion of said bottom liquid.

Claim 11

Dependent Claim 36 words

Process according to claim 8 additionally comprising returning the evaporated portion of said bottom liquid to said rectifying step, and increasing the pressure of said minor fraction of feed prior to said latent heat exchanging step.

Claim 12

Dependent Claim 33 words

Process according to claim 10 additionally comprising counter-currently contacting said bottom liquid enroute to said latent heat exchanging with totally condensing feed step with said evaporated bottom liquid returning to said rectifying step.

Claim 13

Dependent Claim 15 words

Process according to claim 1 wherein said feed fluid mixture is cleaned and compressed air.

Claim 14

Dependent Claim 132 words

In an apparatus for the subambient temperature fractional distillation of a fluid feed mixture comprising a high pressure (HP) rectifying section, and a low pressure (LP) distillation column including a reboiler for exchanging latent heat with HP rectifying section overhead vapor and for providing overhead reflux liquid to both said HP rectifying section and said LP distillation column, the improvement comprising: (a) a means for essentially totally condensing a minor fraction of said feed mixture by exchanging latent heat with a liquid from said HP rectifying section; (b) a means for splitting the condensed feed into at least two streams; and (c) a means for routing one of said strams to an intermediate reflux height of said HP rectifying section, and another to an intermediate reflux height of said LP distillation column.

Claim 15

Dependent Claim 132 words

In an apparatus for the subambient temperature fractional distillation of a fluid feed mixture comprising a high pressure (HP) rectifying section, and a low pressure (LP) distillation column including a reboiler for exchanging latent heat with HP rectifying section overhead vapor and for providing overhead reflux liquid to both said HP rectifying section and said LP distillation column, the improvement comprising: (a) a means for essentially totally condensing a minor fraction of said feed mixture by exchanging latent heat with a liquid from said HP rectifying section; (b) a means for splitting the condensed feed into at least two streams; and (c) a means for routing one of said strams to an intermediate reflux height of said HP rectifying section, and another to an intermediate reflux height of said LP distillation column.

Claim 16

Dependent Claim 46 words

The apparatus according to claim 13 wherein the HP rectifying section liquid supplied to said latent heat exchange is feed height liquid (also called bottom liquid), and additionally comprised of a compressor for increasing the pressure of said minor feed fraction prior to said total condensation.

Claim 17

Dependent Claim 57 words

The apparatus according to claim 14 additionally comprising: (a) a means for returning the vapor effluent from said means for exchanging latent heat to said HP rectifying section; and (b) a work-expander which expands a cold vapor stream derived from said feed mixture and which provides at least part of the power necessary to drive said compressor.

Claim 18

Dependent Claim 38 words

The apparatus according to claim 14 additionally comprising a zone of counter-current vapor liquid contact which is in fluid contact with the bottom of said HP rectifying section and the top of said means for exchanging latent heat.

Claim 19

Dependent Claim 101 words

A process for fractionally distilling a supply of compressed and cleaned air to product oxygen and co-product nitrogen comprising: (a) rectifying a major fraction of said supply air to liquid nitrogen (LIN) overhead product and oxygen-enriched liquid bottom product in a high pressure rectifier; (b) evaporating part of said LIN by exchanging latent heat with a minor fraction of said supply air, which is essentially totally condensed thereby; (c) distilling said bottom product in a N 2 removal column; and (d) refluxing intermediate heights of said HP rectifier and said N 2 removal column with the liquid air from step (b).

Claim 20

Dependent Claim 101 words

A process for fractionally distilling a supply of compressed and cleaned air to product oxygen and co-product nitrogen comprising: (a) rectifying a major fraction of said supply air to liquid nitrogen (LIN) overhead product and oxygen-enriched liquid bottom product in a high pressure rectifier; (b) evaporating part of said LIN by exchanging latent heat with a minor fraction of said supply air, which is essentially totally condensed thereby; (c) distilling said bottom product in a N 2 removal column; and (d) refluxing intermediate heights of said HP rectifier and said N 2 removal column with the liquid air from step (b).

Claim 21

Dependent Claim 22 words

The process according to claim 17 wherein said minor fraction is comprised of between about 8% and 21% of said supply air.

Claim 22

Dependent Claim 22 words

The process according to claim 18 further comprising decreasing the pressure of said LIN below HP rectifier pressure prior to said evaporation.

Claim 23

Dependent Claim 18 words

The process according to claim 18 further comprising increasing the pressure of said LIN prior to said evaporation.

Claim 24

Dependent Claim 17 words

The process according to claim 18 further comprising partially warming and work-expanding said evaporated N 2 .

Claim 25

Dependent Claim 23 words

The process according to claim 18 further comprising partially cooling and work-expanding said minor fraction of suppy air prior to said total condensation.

Claim 26

Dependent Claim 26 words

The process according to claim 18 further comprising additionally compressing said minor fraction of supply air to above supply air pressure prior to said total condensation.

Claim 27

Dependent Claim 35 words

The process according to claim 22 further comprising additionally compressing said minor fraction of supply air prior to said partial cooling; and providing at least part of the power for said compression from said work-expansion.

Claim 28

Dependent Claim 29 words

The process according to claim 18 further comprising additionally distilling the oxygen-argon mixture from said nitrogen removing distillation step so as to yield high purity oxygen and crude argon.

Claim 29

Dependent Claim 69 words

The process according to claim 25 further comprised of: (a) providing overhead reflux to said argon-oxygen distillation step by exchanging latent heat with at least one of: (i) a separate stream of partially depressurized LN 2 from said HP rectifier; (ii) intermediate reboil height liquid from said N 2 removal column; and (iii) the unevaporated remainder of HP rectifier bottom liquid after it has been depressurized and partially evaporated.

Claim 30

Dependent Claim 40 words

The process according to claim 22 wherein said air undergoing total condensation is at a lower pressure than said HP rectifier pressure, and further comprising increasing the pressure of the liquid air enroute to intermediate refluxing of said HP rectifier.

Claim 31

Independent Claim 103 words

An apparatus for producing oxygen and nitrogen by fractional distillation of a supply of compressed and cleaed air comprising: (a) a high pressure (HP) rectifier; (b) a low pressure column including a reboiler/reflux condenser for exchanging latent heat between HP rectifier vapor and LP column liquid; (c) an evaporator for evaporating part of the overhead product liquid nitrogen (LIN) from said HP rectifier by exchanging latent heat with a minor fraction of said supply air; and (d) a means for withdrawing liquid air from said evaporator and splitting it into separate intermediate height reflux streams for said HP rectifier and said LP column.

Claim 32

Independent Claim 103 words

An apparatus for producing oxygen and nitrogen by fractional distillation of a supply of compressed and cleaed air comprising: (a) a high pressure (HP) rectifier; (b) a low pressure column including a reboiler/reflux condenser for exchanging latent heat between HP rectifier vapor and LP column liquid; (c) an evaporator for evaporating part of the overhead product liquid nitrogen (LIN) from said HP rectifier by exchanging latent heat with a minor fraction of said supply air; and (d) a means for withdrawing liquid air from said evaporator and splitting it into separate intermediate height reflux streams for said HP rectifier and said LP column.

Claim 33

Dependent Claim 54 words

The apparatus according to claim 28 further comprised of at least one of: (a) a means for reducing the pressure of the LIN supply to said evaporator to below said HP rectifier pressure; and (b) a means for partially cooling and work-expanding said minor fraction of supply air before routing it to said evaporator.

Claim 34

Dependent Claim 49 words

The apparatus according to claim 28 further comprised of at least one of: (a) a means for increasing the pressure of the LIN supply to said evaporator to above said HP rectifier pressure; and (b) a means for partially warming and work-expanding the evaporated N 2 from said evaporator.

Claim 35

Dependent Claim 46 words

The apparatus according to claim 28 further comprised of at least one of: (a) a means for additionally compressing said minor fraction of supply air; and (b) a means for work-expanding a vapor stream so as to supply at least part of said additional compression power.

Claim 36

Dependent Claim 111 words

A process for the subambient fractional distillation of a supply of pressurized feed gas mixture comprising: (a) providing at least one high pressure (HP) fractionating column comprised of at least one rectifying section, at least one stripping section, a reboiler, and at least one reflux condenser; (b) providing at least one low pressure (LP) distillation column which receives enriched feed mixture from said HP column; (c) increasing the pressure of a minor fraction of the supply mixture; (d) essentially totally condensing said increased-pressure fraction in said reboiler; and (e) splitting the condensed feed into at least two intermediate reflux streams, one for said HP column and another for said LP column.

Claim 37

Dependent Claim 111 words

A process for the subambient fractional distillation of a supply of pressurized feed gas mixture comprising: (a) providing at least one high pressure (HP) fractionating column comprised of at least one rectifying section, at least one stripping section, a reboiler, and at least one reflux condenser; (b) providing at least one low pressure (LP) distillation column which receives enriched feed mixture from said HP column; (c) increasing the pressure of a minor fraction of the supply mixture; (d) essentially totally condensing said increased-pressure fraction in said reboiler; and (e) splitting the condensed feed into at least two intermediate reflux streams, one for said HP column and another for said LP column.

Claim 38

Dependent Claim 49 words

The process according to claim 32 additionally comprising controlling the amount of feed mixture which is totally and condensed and controlling the intermediate reflux split proportions so as to achieve a pinch condition at both the intermediate reflux heights and the feed heights of said HP and LP columns.

Claim 39

Dependent Claim 28 words

The process according to claim 32 wherein the feed mixture is air and wherein said minor fraction comprises between about 8% and B; 21% of said supply air.

Claim 40

Dependent Claim 32 words

The process according to claim 34 additionally comprising work-expanding a cooled vapor stream derived from said supply air; and directly driving a compressor with the resulting work to provide said pressure increase.

Claim 41

Dependent Claim 37 words

The process according to claim 32 additionally comprising partially condensing a major fraction of said supply air by exchanging latent heat with LP column bottom liquid and then feeding the partially condensed air to said HP column.

Claim 42

Dependent Claim 72 words

The process according to claim 36 wherein said supply mixture is air and additionally comprising: (a) refluxing the overhead of said HP column by exchanging latent heat with bottom liquid of an argon-oxygen distillation column; (b) feeding said argon-oxygen distillation column with a liquid withdrawn from an intermediate height below the feed height of said LP column; and (c) withdrawing product high purity gaseous oxygen from the sump of said LP column.

Claim 43

Dependent Claim 67 words

The process according to claim 36 wherein said supply mixture is air and additionally comprising: (a) refluxing the overhead of said HP column by exchanging latent heat with at leat one of: (i) LP column intermediate height liquid; and (ii) at least part of the depressurized bottom product from said HP column; and (b) withdrawing product gaseous low purity oxygen from the sump of said LP column.

Claim 44

Dependent Claim 65 words

The process according to claim 34 additionally comprising: (a) refluxing the overhead of said HP column by exchanging latent heat with LP column bottom liquid and reboiling the LP column thereby; and (b) providing part of the reflux to an argon sidearm incorporated as part of said LP column by exchanging latent heat with part of the liquid nitrogen overhead product from said HP column.

Claim 45

Dependent Claim 86 words

The process according to claim 36 wherein said supply mixture is air and additionally comprising: (a) refluxing the overhead of said HP column by exchanging latent heat with at least one of: (i) LP column intermediate height liquid; and (ii) at least part of the depressurized bottom product from said HP column; (b) refluxing the overhead of said LP column at least in part by exchanging latent heat with depressurized LP column bottom liquid; and (c) withdrawing product gaseous nitrogen from the overheads of both columns.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-08-07	1993-02-06	1993-08-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-08-07	1997-02-06	1997-08-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-08-07	2001-02-06	2001-08-08	$7700.00	Window Closed / Lapsed

Rectifier liquid generated intermediate reflux for subambient cascades

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