Air separation plant and method for operating an air separation plant for the low-temperature separation of air

Abstract

An air separation plant (10) for the low-temperature separation of air (12) is presented, comprising a regenerable purification device (16) for separating residual moisture and carbon dioxide (CO2) from the supplied air (12). The purification device (16) has a sorbent (30) that can be regenerated by flushing with a heated regeneration agent (42), and a regeneration agent supply unit (34) for supplying the heated regeneration agent (42) to the regenerable purification device (16). According to the invention, a steam generation unit (40) is provided, which is optionally fluidically connected or connectable to the regeneration agent supply unit (34) in order to supply steam (H2O) as a regeneration agent (42) to the regenerable purification device (16) for flushing the sorbent (30).

Description

Prior ArtThe invention relates to an air separation plant for low-temperature separation of air, having a regeneratable purification apparatus for separating residual moisture and carbon dioxide from the fed air, wherein the purification apparatus has a sorption agent which can be regenerated by flushing by means of a heated regeneration agent, that is to say by partial pressure change during energy recirculation, and a regeneration agent feed unit for feeding the heated regeneration agent into the regeneratable purification apparatus. The invention further relates to a process for operating an air separation plant for low-temperature separation of air, wherein residual moisture and carbon dioxide are separated from a fed air by means of a regeneratable purification apparatus comprising a sorbent and the sorbent is regenerated by flushing by means of a heated regenerating agent with discharge of the carbon dioxide.Worldwide, there are installations which already today draw in atmospheric air on a large scale and separate the carbon dioxide therefrom. These include, in particular, cryogenic distillation plants in which, in particular, oxygen, nitrogen, argon and, if appropriate, further noble gases are obtained from the air by low-temperature distillation. Since water and carbon dioxide must necessarily be removed completely (residual content in the ppb range) before the deep cold distillation, adsorption systems with molecular sieves are located as pretreatment stages for separating water (air humidity) and carbon dioxide before the rectification or distillation column. The regeneration of such molecular sieves is generally carried out with nitrogen, which is removed from the distillation plant, the carbon dioxide after desorption being blown off unused together with the nitrogen back into the atmosphere.DE 10 2009 060 842 A1 discloses an air separation plant which delivers at least one nitrogen product. The air separation plant has a regeneratable raw air purification device and a solar thermal heater for heating the nitrogen product, wherein a piping for supplying the heated nitrogen product as purge gas to the raw air purification device is provided.Disclosure of the InventionThe present invention relates to an air separation plant for low-temperature separation of air of the type described in the introduction, wherein a water vapor generation unit is provided which is optionally fluidically connected or connectable to the regeneration agent supply unit in order to supply water vapor as regeneration agent to the regeneratable purification apparatus for flushing the sorbent.The present invention further provides a process for operating an air separation plant for low-temperature separation of air in accordance with the type described in the introduction, wherein, for the regeneration, water vapor generated by means of a water vapor generation unit is fed as regeneration agent to the regeneratable purification apparatus for flushing the sorbent.Accordingly, according to the invention, in an air separation plant for low-temperature separation, the purification stage for separating or separating residual moisture (H2O) and carbon dioxide (CO2) from atmospheric air is modified in such a way that the regeneration agent nitrogen (N2) (or oxygen or noble gas) is replaced by, in particular, superheated steam. In other words, in air separation plants according to the prior art, the carbon dioxide is returned to the atmosphere again diluted by desorption with nitrogen. In contrast, according to the invention, water vapor is used for desorption, since water vapor and carbon dioxide can easily be separated by condensing out water and thus the carbon dioxide does not pass back into the atmosphere again, but is either available for a CO2 kreislauf business or can be stored finally in the geological subsurface.It is particularly advantageous that such air separation plants are already in wide use worldwide in large numbers and are directly in industrial complexes, in particular for the production of industrial oxygen. A connection to future CO2 pipeline can be implemented easily for such sites and further processing to synthetic fuels by means of hydrogen from green power can also be carried out there easily or is already tested. Furthermore, the cost for the re-upgrading of such air separation plants is possible with little cost.The air separation plant is designed to separate air into at least one of its constituents, in particular oxygen, nitrogen, argon and / or further noble gases, by means of a low-temperature separation process or cryogenic distillation process. The air separation plant can in principle be designed or operable according to the air separation plant from DE 10 2009 060 842 A1 described in the introduction.The air separation plant has a regeneratable purification apparatus which is designed to separate residual moisture and carbon dioxide from the air fed in a pretreatment step. The regeneratable cleaning device is in particular designed to separate off the residual moisture and the carbon dioxide by means of a sorption process and a desorption process.Accordingly, the sorption process can take place in particular by means of at least one of the following methods or mixed forms thereof:chemical adsorption methodphysical adsorption process- chemical absorption methodphysical absorption methodAnalogously, the desorption process can take place in particular by means of at least one of the following methods or mixed forms thereof:chemical desorption methodphysical desorption methodFor this purpose, the cleaning device has a sorption agent which can be regenerated by flushing by means of a heated regeneration agent, i.e. by partial pressure change when the energy is supplied.The sorbent is preferably solid. The sorbent can comprise, in particular, a solid (appropriately functionalized) adsorbent and / or absorbent. Accordingly, the sorbent can have, for example, a particulate or fibrous or nonwoven solid as a support structure with a base material which is selected from the group consisting of: resins, polymers, ceramics, zeolites, silicates, organometallic compounds, organic materials such as cellulose or activated carbon, and combinations thereof. The base material may in turn be specifically functionalized with amines, potassium carbonate or other components configured to chemically or physically bind CO2.The sorbent preferably has a regeneration temperature of less than 100° C. The sorbent Lewatit VP OC 1065 can be mentioned by way of example. Desorption of CO2and water from lewatit can take place at 100° C., with subsequent removal of the carbon dioxide and of the water via, for example, a cold trap. Lower temperatures are thereby possible than when using molecular sieves, e.g. zeolite, at which the temperatures for regeneration with nitrogen are typically significantly above 100° C., for example 180° C.The cleaning device can further comprise at least one of the following units:pumping unit or vacuum pump for providing an overpressure and / or underpressure for the desorption process;sensor unit for the sorption and desorption process;control unit for controlling and / or regulating the sorption and desorption process.The air separation plant has a regeneration agent supply unit which is designed to supply the heated regeneration agent into the regeneratable purification apparatus. For this purpose, the regeneration agent supply unit can have, in particular, at least one fluid line, a plurality of fluid lines or a fluid line system with corresponding valves.The water vapor generation unit is designed to generate or provide water vapor in a corresponding quantity as a regeneration agent for the regeneration process or desorption process. For the selective fluidic connection or connectivity to the regeneration agent supply unit, the water vapor generation unit can have corresponding valves.Advantageously, a water condenser unit or a water condenser is provided downstream of the water vapor generation unit and the regeneratable cleaning device in order to separate the water vapor from the separated carbon dioxide. Accordingly, the water vapor is advantageously subsequently separated, i.e. after the regeneration or desorption, from the separated carbon dioxide by means of a water condenser unit or a water condenser in order to recover the carbon dioxide.Advantageously, a carbon dioxide storage unit is further provided downstream of the water condenser unit for storing the separated dehumidified carbon dioxide. Accordingly, the dehumidified carbon dioxide is advantageously stored subsequently, i.e. after the separation of the water vapor, by means of a carbon dioxide storage unit. The carbon storage unit can be, for example, a metallic pressure accumulator or a CO2 storage device under the earth.It is also advantageous if an inerting agent feed unit or the regenerating agent feed unit is also optionally fluidically connected or connectable to a rectification column of the air separation plant in order to feed nitrogen separated from the air to the regeneratable purification apparatus as inerting agent before the flushing of the sorbent with steam in order to remove oxygen present from the purification apparatus before the regeneration. Accordingly, before the sorbent is flushed with steam, nitrogen which has been obtained in the air separation plant is fed to the regeneratable purification apparatus for inertization, in order to remove oxygen present from the purification apparatus.DRAWINGSThe invention is explained in more detail below by way of example with reference to the attached drawings. The following are shown: FIG. 1 shows a basic structure of an air separation plant for low-temperature separation of air according to the prior art; and FIG. 2 shows a basic structure of an air separation plant for low-temperature separation of air according to an exemplary embodiment of the invention.In the following description of the prior art and preferred exemplary embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the different figures and acting in a similar manner, wherein a repeated description of the elements is omitted.FIG. 1 shows a basic structure of an air separation plant 100 for low-temperature separation of air 12 according to the prior art. The air separation plant 100 is designed to separate the air 12 into oxygen O2and nitrogen N2by means of a low-temperature separation process or cryogenic distillation process.For this purpose, the air separation plant 100 has a compressor 14 for compressing the fed air 12, a regeneratable purification apparatus 16 for separating or separating residual moisture H 20 and carbon dioxide CO 2 from the fed air 12, a cooler 18, a further compressor 20, a expansion turbine 22, a heat exchanger 24, a rectification or distillation column 26 and a further cooler 28.The cleaning device 16 is designed as a sorption device 16 and has a sorption agent 30 or adsorbent 30, which can be regenerated by flushing by means of a heated regeneration agent 32. Accordingly, the air separation plant 100 further comprises a regeneration agent supply unit 34 for supplying the heated regeneration agent 32 into the regeneratable purification apparatus 16. The regeneration agent supply unit 34 is designed as a fluid line 34.According to the prior art, the regeneration agent feed unit 34 or the fluid line 34 of the air separation plant 100 is fluidically connected to the rectification or distillation column 26 in order to feed the nitrogen N 2 separated in the rectification or distillation column 26 as regeneration agent 32 into the regeneratable purification apparatus 16. In this case, after regeneration or desorption, the nitrogen N2is discharged together with the separated carbon dioxide CO2from the cleaning device 16 or sorption device 16 by means of a nitrogen valve 36 into the environment 38.FIG. 2 now shows a schematic structure of an air separation plant 10 for low-temperature separation of air 12 according to an exemplary embodiment of the invention. In contrast to the air separation plant 100 according to the prior art from FIG. 1, the air separation plant 10 according to the invention has a water vapor generation unit 40 which is optionally fluidically connected or connectable to the regeneration agent supply unit 34 or the fluid line 34 in order-instead of nitrogen N2-to supply water vapor H2O as regeneration agent 42 to the regeneratable cleaning device 16 for flushing the sorbent 30. The sorbent 30 has a regeneration temperature of less than 100° C. in this case.To obtain the separated carbon dioxide CO2, the air separation plant 10 according to the invention further comprises a water condenser unit 44 or a water condenser 44 in order to separate the water vapor H2O from the separated carbon dioxide CO2, and a carbon dioxide storage unit 46 in order to store the separated dehumidified carbon dioxide CO2 without the latter being discharged into the environment 38 in the process.If an exemplary embodiment comprises an "and / or" combination between a first feature and a second feature, this is to be read in such a way that the exemplary embodiment has both the first feature and the second feature according to one embodiment and either only the first feature or only the second feature according to a further embodiment.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2009 060 842 A1 [0003, 0008]

Claims

Air separation plant (10) for low-temperature separation of air (12), having a regeneratable purification apparatus (16) for separating residual moisture and carbon dioxide (CO2) from the supplied air (12), wherein the purification apparatus (16) has a sorption agent (30) which can be regenerated by flushing by means of a heated regeneration agent (42), and a regeneration agent feed unit (34) for feeding the heated regeneration agent (42) into the regeneratable purification apparatus (16), characterized bya steam generation unit (40) which is optionally fluidically connected or can be connected to the regeneration agent feed unit (34) in order to feed steam (H2O) as regeneration agent (42) to the regeneratable purification apparatus (16) for flushing the sorption agent (30).Air separation plant (10) according to claim 1, characterized bya water condenser unit (44) downstream of the water vapor generation unit (40) and the regeneratable purification device (16) for separating the water vapor (H2O) from the separated carbon dioxide (CO2).The air separation plant (10) of claim 2, characterized bya carbon dioxide storage unit (46) downstream of the water condenser unit (44) for storing the separated de-moistened carbon dioxide (CO2).Air separation plant (10) according to one of the preceding claims, characterized in that an inerting agent feed unit or the regenerating agent feed unit (34) is also optionally fluidically connected or connectable to a rectification column (26) of the air separation plant (10) in order to feed nitrogen (N2) separated from the air (12) to the regeneratable purification apparatus (16) as inerting agent before the sorption agent (30) is flushed with steam (H2O) in order to remove oxygen present from the purification apparatus (16).Air separation plant (10) according to one of the preceding claims, characterized in that the sorption agent (30) has a regeneration temperature of less than 100°C.Method (100) for operating an air separation plant (10) for low-temperature separation of air (12), wherein residual moisture and carbon dioxide (CO2) are separated from the supplied air (12) by means of a regeneratable purification apparatus (16) having a sorption agent (30), and the sorption agent (30) is regenerated by flushing by means of a heated regeneration agent (42) with discharge of the carbon dioxide (CO2), characterized in that, for regeneration, water vapor (H2O) generated by means of a water vapor generation unit (40) is supplied to the regeneratable purification apparatus (16) for flushing the sorption agent (30).Method (100) according to claim 6, characterised in that subsequently the water vapor (H2O) is separated from the separated carbon dioxide (CO2) by means of a water condenser unit (44) in order to obtain the carbon dioxide (CO2).Method (100) according to Claim 7, characterized in that the dehumidified carbon dioxide (CO2) is subsequently stored by means of a carbon dioxide storage unit (46).Method (100) according to one of Claims 6 to 8, characterized in that nitrogen (N2) obtained in the air separation plant (10) is fed to the regeneratable purification apparatus (16) for inerting purposes before the sorption agent (30) is flushed with steam (H2O) in order to remove oxygen present from the purification apparatus (16).

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