METHOD AND DEVICE FOR SEPARATION AT SUB-AMBIENT TEMPERATURE
In a method for separation at sub-ambient temperature, a mixture of fluid at sub-ambient temperature is sent to a system of separation columns comprising at least one separation column, a fluid enriched in a lighter component of the mixture leaves the top of one column of the system and a fluid enriched in a heavier component is withdrawn from the bottom of one column of the system, the cold source of a heat pump using the magnetocaloric effect is thermally connected to a first zone of one column of the system and the hot source of the same heat pump is thermally connected to a second zone of the same or of another column of the system.
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This application is a §371 of International PCT Application PCT/FR2014/052241, filed Sep. 10, 2014, which claims the benefit of FR1358666, FR1358667, and FR1358668, all of which were filed Sep. 10, 2013 and are herein incorporated by reference in their entireties.
TECHNICAL FIELD OF THE INVENTIONThe present invention relates to a method and to a device for separation by separating at sub-ambient, or even cryogenic, temperature. The separation may be a separation by distillation and/or by dephlegmation and/or by absorption. The equipment used for this separation will be referred to as a “column”. Thus, a column may for example be a distillation or absorption column. Reduced to its simplest expression, it may be a phase separator. Otherwise, a column may also be a device in which dephlegmation takes place.
BACKGROUND OF THE INVENTIONMagnetic refrigeration relies on the use of magnetic materials that exhibit a magnetocaloric effect. Reversible, this effect is manifested by a variation in temperature when subjected to the application of an external magnetic field. The optimum ranges within which these materials are used lie in the vicinity of their Curie temperature (Tc). This is because the greater the variations in magnetization and, therefore, the changes in magnetic entropy, the greater the changes in temperature. The magnetocaloric effect is said to be direct when the temperature of the material increases when placed in a magnetic field, and indirect when it cools when placed in a magnetic field. The remainder of the description will be given for the direct case, but it is obvious to a person skilled in the art how to reapply this to the indirect case. There are many thermodynamic cycles based on this principle.
A conventional magnetic refrigeration cycle consists i) in magnetizing the material in order to increase its temperature, ii) in cooling the material for a constant magnetic field in order to dissipate heat, iii) in demagnetizing the material in order to cool it and iv) in heating the material in a constant (generally zero) magnetic field in order to absorb heat.
A magnetic refrigeration device employs elements made of magnetocaloric material, which generate heat when magnetized and absorb heat when demagnetized. They may employ a magnetocaloric material regenerator to amplify the temperature difference between the “hot source” and the “cold source”: the magnetic refrigeration is then said to be magnetic refrigeration employing active regeneration.
It is known practice to use the magnetocaloric effect to supply cold to a method for separating air by cryogenic distillation.
U.S. Pat. No. 6,502,404 describes the use of the magnetocaloric effect to supply cold (needed to provide the refrigeration balance of the method) to a cryogenic method for separating the gas of the air, the separation energy being conventionally supplied by pressurized air allows the operation of the vaporizer-condenser of the double column (it being possible for the low-pressure column to be reduced to a simple vaporizer in the case of a nitrogen generator).
SUMMARY OF THE INVENTIONThe present invention tackles the problem of the transfer of heat from one place in a device for separation by distillation and/or by dephlegmation and/or by absorption at sub-ambient temperature, which place is considered to be a cold source, to another place of said device considered to be a hot source.
It has long been known to use one and the same circuit to provide both heat to the reboiler of a distillation column and frigories to the condenser of this same column. U.S. Pat. No. 2,916,888 discloses one example for the distillation of hydrocarbons.
A heat pump is a thermodynamic device that allows a quantity of heat to be transferred from a medium considered to be the “emitter” and referred to as the “cold source” from which heat is extracted, to a medium considered to be the “receiver” and referred to as the “hot source” to which the heat is supplied, the cold source being at a colder temperature than the hot source.
The conventional cycle used in the prior art for this type of application is a thermodynamic cycle of compressing—cooling (condensing)—expanding—reheating (vaporizing) a refrigeration fluid.
An ambient temperature is the temperature of the ambient air in which the method is situated or, alternatively, a temperature of a cooling water circuit connected with the air temperature.
A sub-ambient temperature is at least 10° C. below ambient temperature.
U.S. Pat. No. 4,987,744 describes a cryogenic distillation method in which a heat pump transfers heat from one point of one column, which is at a cryogenic temperature, to another point on the column, which is likewise at a cryogenic temperature. The heat pump comprises two closed refrigerant circuits thermally connected to one another, each of the circuits comprising a compression step and a cooling step using a fluid at ambient temperature (air, water).
One subject of certain embodiments of the invention provide a method for separation at sub-ambient, or even cryogenic, temperature, in which a mixture of fluid at sub-ambient, or even cryogenic, temperature is sent into a system of separation columns comprising at least one separation column, a fluid enriched in a lighter component of the mixture leaves the top of one column of the system and a fluid enriched in a heavier component is withdrawn from the bottom of one column of the system, in which the cold source of a heat pump using the magnetocaloric effect is directly or indirectly thermally connected to a first zone of a column of the system and the hot source of the same heat pump is directly or indirectly thermally connected to a second zone of the same or of another column of the system, the minimum temperature of the first zone being lower than the maximum temperature of the second zone.
According to other optional subjects:
-
- a gas of the first zone condenses at least partially and is possibly sent back to the first zone;
- a liquid of the second zone is vaporized at least partially and is possibly sent back to the second zone;
- at least a fluid coming from the first or second zone is placed in direct contact with a magnetocaloric material of a heat pump using the magnetocaloric effect;
- the exchange of heat is performed at least in part between a fluid coming from the first or second zone and a heat-transfer fluid that has been in contact with a magnetocaloric material of a heat pump using the magnetocaloric effect via an exchanger;
- the exchange of heat is performed at least in part between a fluid coming from a first or second zone and a heat-transfer fluid that has been in contact with a magnetocaloric material of a heat pump using the magnetocaloric effect through an intermediate heat-transfer circuit.
- the heat-transfer fluid is a liquid;
- the heat-transfer fluid does not change phase during the method;
- the heat-transfer fluid remains at a constant pressure during the method;
- the heat-transfer fluid is not compressed by a compressor;
- the heat pump does not transfer heat to outside the separation device;
- the heat pump transfers heat only from the hot source to the cold source;
- the hot source connected to the second zone operates at the highest temperature of the heat pump;
- the heat pump operates entirely at cryogenic temperatures;
- the heat pump is arranged in the same cold box as the system of columns;
- the mixture is air;
- the heat pump using the magnetocaloric effect condenses a nitrogen-enriched gas in the first zone and vaporizes an oxygen-enriched liquid in the second zone;
- a plurality of heat pumps is employed, heat being supplied to several heat pumps from a first zone and/or heat coming from several heat pumps being sent to a second zone;
- the main components of the mixture are carbon monoxide and/or carbon dioxide and/or hydrogen and/or methane and/or nitrogen;
- in order to produce a liquid in the bottom of the column containing more than 97 mol % oxygen, argon is removed from the liquid withdrawn at the bottom of the column by separating an argon-enriched intermediate gas from the column in a distillation column in order to produce a flow that is more rich in argon;
- use is made of several heat pumps using the magnetocaloric effect, one of which is used to condense an intermediate gas tapped off higher up the column and another is used to vaporize an intermediate liquid from lower down the column;
- to produce a column bottom liquid containing less than 96.5 mol % oxygen, in which a heat pump using the magnetocaloric effect is used to vaporize an intermediate liquid from lower down the column.
Another subject of the invention is a device for separation at sub-ambient, or even cryogenic, temperature, comprising a system of separation columns comprising at least one separation column to which a mixture of fluid at sub-ambient, or even cryogenic, temperature is sent, a pipe for withdrawing a fluid enriched with a lighter component of the mixture from the top of one column of the system and a pipe for withdrawing a fluid enriched in a heavier component from the bottom of one column of the system, in which the cold source of a heat pump using the magnetocaloric effect is directly or indirectly thermally connected to a first zone of a column of the system and the hot source of the same heat pump being directly or indirectly thermally connected to a second zone of the same or of another column of the system, the arrangement of the first and second zones in the column or columns being such that the minimum temperature of the first zone is lower than the maximum temperature of the second zone.
According to other optional aspects, the device comprises:
-
- means for sending a gas from the first zone to condense;
- means for sending the condensed gas to the first zone;
- means for sending a liquid from the second zone to vaporize at least partially;
- means for sending the vaporized liquid to the second zone;
- means for placing at least a fluid coming from the first or second zone into direct contact with a magnetocaloric material of a heat pump using the magnetocaloric effect;
- the exchange of heat is at least partially carried out between a fluid coming from the first or second zone and a heat-transfer fluid that has been in contact with a magnetocaloric material of a heat pump using the magnetocaloric effect through an exchanger;
- the exchange of heat is at least partially carried out between a fluid coming from the first or second zone and a heat-transfer fluid that has been in contact with a magnetocaloric material of a heat pump using the magnetocaloric effect through an intermediate heat-transfer circuit;
- the mixture is air;
- the heat pump using the magnetocaloric effect is capable of condensing a nitrogen-enriched gas in the first zone and vaporizes an oxygen-enriched liquid in the second zone;
- a plurality of heat pumps, means for supplying heat to several heat pumps from a first zone and/or means for sending heat from several heat pumps to a second zone;
- in order to produce a column bottom liquid containing more than 97 mol % of oxygen, a distillation column for eliminating argon from the liquid withdrawn at the bottom of the column by separating an argon-enriched intermediate gas from the column in order to produce a more argon-rich flow;
- several heat pumps using the magnetocaloric effect, one of which is used to condense an intermediate gas tapped off higher up the column and another is used to vaporize an intermediate liquid from lower down the column.
These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it can admit to other equally effective embodiments.
The invention will be described in greater detail with reference to the figures.
In
In
In
In
A liquid flow 61 enriched in B (oxygen) and a liquid flow 63 enriched in A (nitrogen) are withdrawn from the medium-pressure column 3 and sent to the low-pressure column 5.
In
Nitrogen 57 is withdrawn from the top of the low-pressure column 5, heated up in the subcooler 45 and in the exchanger 13 before being used at least in part for the regeneration of the unit 11.
Compared with the conventional double column configuration, the use of a heat pump employing the magnetocaloric effect as illustrated in
The method in
By comparison with the conventional double column configuration with double vaporizer in the low-pressure column, the use of heat pumps using the magnetocaloric effect as illustrated in
While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.
“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.
Claims
1-15. (canceled)
16. A method for separation at sub-ambient temperature, the method comprising the steps of:
- sending a mixture of fluid at sub-ambient temperature into a system of separation columns comprising at least one separation column; and
- withdrawing a fluid enriched in a lighter component of the mixture from the top of one column of the system and withdrawing a fluid enriched in a heavier component from the bottom of one column of the system;
- wherein the cold source of a heat pump using the magnetocaloric effect is directly or indirectly thermally connected to a first zone of a column of the system and the hot source of the same heat pump is directly or indirectly thermally connected to a second zone of the same or of another column of the system,
- wherein the minimum temperature of the first zone is lower than the maximum temperature of the second zone.
17. The method as claimed in claim 16, in which a gas of the first zone condenses at least partially and is possibly sent back to the first zone.
18. The method as claimed in claim 16, in which a liquid of the second zone is vaporized at least partially and is possibly sent back to the second zone.
19. The method as claimed in claim 16, in which at least a fluid coming from the first or second zone is placed in direct contact with a magnetocaloric material of a heat pump using the magnetocaloric effect.
20. The method as claimed in claim 16, in which the exchange of heat is performed at least in part between a fluid coming from the first or second zone and a heat-transfer fluid that has been in contact with a magnetocaloric material of a heat pump using the magnetocaloric effect via an exchanger.
21. The method as claimed in claim 16, in which the exchange of heat is performed at least in part between a fluid coming from the first or second zone and a heat-transfer fluid that has been in contact with a magnetocaloric material of a heat pump using the magnetocaloric effect through an intermediate heat-transfer circuit.
22. The method as claimed in claim 16, in which the mixture is air.
23. The method as claimed in claim 22, in which the heat pump using the magnetocaloric effect condenses a nitrogen-enriched gas in the first zone and vaporizes an oxygen-enriched liquid in the second zone.
24. The method as claimed in claim 16, in which a plurality of heat pumps is employed, heat being supplied to several heat pumps from a first zone and/or heat coming from several heat pumps being sent to a second zone.
25. The method as claimed in claim 16, in which the main components of the mixture are carbon monoxide and/or carbon dioxide and/or hydrogen and/or methane and/or nitrogen.
26. The method as claimed in claim 16, in which in order to produce a liquid in the bottom of the column containing more than 97 mol % oxygen, argon is removed from the liquid withdrawn at the bottom of the column by separating an argon-enriched intermediate gas from the column in a distillation column in order to produce a flow that is more rich in argon.
27. The method as claimed in claim 16, in which use is made of several heat pumps using the magnetocaloric effect, one of which is used to condense an intermediate gas tapped off higher up the column and another is used to vaporize an intermediate liquid from lower down the column.
28. The method as claimed in claim 16, to produce a column bottom liquid containing less than 96.5 mol % oxygen, in which a heat pump using the magnetocaloric effect is used to vaporize an intermediate liquid from lower down the column.
29. The method as claimed in claim 16, in which the hot source operates at the highest temperature of the heat pump.
30. A device for separation at sub-ambient temperature, comprising a system of separation columns comprising at least one separation column to which a mixture of fluid at sub-ambient temperature is sent, a pipe for withdrawing a fluid enriched with a lighter component of the mixture from the top of one column of the system and a pipe for withdrawing a fluid enriched in a heavier component from the bottom of one column of the system, in which the cold source of a heat pump using the magnetocaloric effect is directly or indirectly thermally connected to a first zone of a column of the system and the hot source of the same heat pump being directly or indirectly thermally connected to a second zone of the same or of another column of the system, the arrangement of the first and second zones in the column or columns being such that the minimum temperature of the first zone is lower than the maximum temperature of the second zone.
Type: Application
Filed: Sep 10, 2014
Publication Date: Jul 28, 2016
Applicant: L'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude (Paris)
Inventors: Guillaume CARDON (Paris), Antony CORREIA ANACLETO (Creteil), Benoît DAVIDIAN (Saint Maur des Fosses), Clement LIX (Versailles), Bernard SAULNIER (La Garenne Colombes)
Application Number: 15/021,031