METHOD FOR REHEATING AN ATMOSPHERIC VAPORIZER USING A GAS ORIGINATING FROM A CRYOGENIC AIR-SEPARATION UNIT

Abstract

In a method for reheating an atmospheric vaporizer, a cryogenic liquid is vaporized by heat exchange with ambient air in the atmospheric vaporizer and to reheat the vaporizer, a gas is sent thereto at a temperature of at least 0 C., this gas originating from a cryogenic distillation air separation unit.

Claims

1. A method for reheating, even de-icing, an atmospheric vaporizer in which: i) in a normal operation, vaporizing a cryogenic liquid having as its main component oxygen, nitrogen or argon originating from a source by heat exchange with ambient air in the atmospheric vaporizer; and ii) in a reheating phase, no longer sending the cryogenic liquid from the source to the atmospheric vaporizer but, instead, sending a gas to the atmospheric vaporizer at a temperature of at least 0 C., wherein said gas originates from a cryogenic distillation air separation unit, wherein the gas sent to the atmospheric vaporizer in the reheating phase is a stream of air purified of water and of carbon dioxide taken from the air supply of the cryogenic distillation air separation unit.

2. The method according to claim 1, in which the source of the cryogenic liquid is the cryogenic distillation air separation unit.

3. The method according to claim 1, in which the main component of the cryogenic liquid is oxygen.

4. The method according to claim 1, in which the gas sent to the atmospheric vaporizer in reheating phase is at a temperature of at least 20 C.

5. The method according to claim 1, in which the gas sent to the atmospheric vaporizer in reheating phase is at a temperature of at least 50 C.

6. The method according to claim 1, in which the gas sent to the atmospheric vaporizer in the reheating phase provides sufficient heat to de-ice the atmospheric vaporizer.

7. The method according to claim 1, in which, during the reheating phase, the atmospheric temperature is not greater than 0 C.

8. The method according to claim 1, further comprising an absence of using electrical means to heat the atmospheric vaporizer in the reheating phase.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawing(s). It is to be noted, however, that the drawing(s) 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.

[0030] FIG. 1 shows an embodiment of the invention.

[0031] FIG. 2 shows an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0032] The method according to the invention will be described in more detail with reference to the figures.

[0033] FIG. 1 shows the method for reheating an atmospheric vaporizer by using air originating from an air separation unit.

[0034] In normal operation, a cryogenic liquid 1 having as its main component oxygen, nitrogen or argon is withdrawn from a storage S. The liquid is sent through a valve V1 to a vaporizer V by a duct 5. The liquid is vaporized in the vaporizer by heat exchange with the air and the gas formed is sent through the valve V3 to a duct 11 by which it supplies a client.

[0035] In the case where the vaporizer is covered with ice, it is necessary to heat the vaporizer V and, for this, the sending of the liquid 1 to the vaporizer is stopped.

[0036] In normal operation, air is sent to an air separation unit ASU where it is purified of water and of carbon dioxide in a purification unit. At the output of the purification unit, it is cooled and sent to a distillation column to be separated.

[0037] When the vaporizer V has to be reheated, at the output of the purification unit, the air is divided into two parts. A first part is cooled and sent to a distillation column to be separated. A second part 3 is heated to at least 0 C., maybe to at least 20 C., and preferably to at least 50 C. in a reheater R, for example an electrical reheater or steam reheater.

[0038] This air is sent to the atmosphere by the valve V3, V5 and the duct 9 after having circulated in the vaporizer V to reheat it.

[0039] The main drawback with this solution is the need to restore the content of the vaporizers V after the de-icing operation.

[0040] According to the method of FIG. 2, the reheating of the vaporizer is performed with a gas produced by distillation in the air separation unit ASU, preferably having the same main component as the cryogenic liquid.

[0041] In normal operation, a cryogenic liquid 1 having as its main component oxygen, nitrogen or argon is withdrawn from a storage S. The liquid is sent through a valve V1 to a vaporizer V by a duct 5. The liquid is vaporized in the vaporizer by heat exchange with the air and the gas formed is sent through the valve V3 to a duct 11 by which it supplies a client.

[0042] In the case where the vaporizer is covered with ice, it is necessary to heat the vaporizer V and, for this, the sending of the liquid 1 to the vaporizer is stopped.

[0043] In normal operation, air is sent to an air separation unit ASU where it is purified of water and of carbon dioxide in a purification unit. At the output of the purification unit, it is cooled and sent to a distillation column to be separated to form a gas having as its main component oxygen, nitrogen or argon 2. The gas is either output from a distillation column in gaseous form and reheated in a heat exchanger where the air supply is cooled or output from a distillation column in liquid form and vapourized and reheated in a heat exchanger where the air supply is cooled. In this way, it is at a minimum temperature of 0 C. in most cases.

[0044] When the vaporizer V has to be reheated, at the output of the purification unit, at least a part of the gas 3 is sent to the vaporizer to reheat it and preferably de-ice it, possibly after reheating in a reheater (not illustrated). If the main component of the gas 3 and that of the liquid 1 are the same, the gas 3 can be sent to the client by the duct 11. Otherwise, it can be rejected to the atmosphere.

[0045] In a particular case illustrated in FIG. 2, the gas 2 is divided into two parts 3, 13. A first part at at least 0 C., perhaps at at least 20 C., preferably at at least 50 C. is sent to reheat the vaporizer V. The gas 3 may if necessary be reheated upstream of the vaporizer V. The second part of the gas 13 is expanded in a valve V2 and is mixed with the gas 3 that was used for the reheating of V downstream of the valve V3. Thus, the two parts 3, 13 are sent to the client by the duct 11.

[0046] A valve V4 can be closed in order to send the gas which was used for the reheating to the air via the duct 15. In this case, it is possible to reheat, even de-ice, the vaporizer V and to vent the reheating gas, even de-icing gas, to the atmosphere, while a part of the production 13 is sent to the client.

[0047] Once the de-icing is done, normal operation of the method is resumed.

[0048] The main advantages of this solution are: [0049] that the product is not lost during the de-icing period, [0050] that the restoration of content is not necessary, unlike the solution of FIG. 1 presented above.

[0051] The main drawback is the need to increase the pressure of the gas produced in order to compensate for the headloss of the vaporizers. This may prove difficult when the gas is produced at low pressure, for example nitrogen originating from the low-pressure column of a double column. In this case, the solution of FIG. 1 should be prioritized.

[0052] In the case of the two figures, the storage S can be supplied from the air separation unit ASU or not.

[0053] The reheating gas 3 can be used in addition to a reheater.

[0054] 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.

[0055] The singular forms a, an and the include plural referents, unless the context clearly dictates otherwise.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.