EP3771873A1 - Procédé et installation de séparation d'air à basse température - Google Patents

Procédé et installation de séparation d'air à basse température Download PDF

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Publication number
EP3771873A1
EP3771873A1 EP19020450.3A EP19020450A EP3771873A1 EP 3771873 A1 EP3771873 A1 EP 3771873A1 EP 19020450 A EP19020450 A EP 19020450A EP 3771873 A1 EP3771873 A1 EP 3771873A1
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EP
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Prior art keywords
column
overhead gas
operating mode
gas condensate
air separation
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EP19020450.3A
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German (de)
English (en)
Inventor
Dimitri GOLUBEV
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Linde GmbH
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Linde GmbH
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Priority to EP19020450.3A priority Critical patent/EP3771873A1/fr
Publication of EP3771873A1 publication Critical patent/EP3771873A1/fr
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04436—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using at least a triple pressure main column system
    • F25J3/04442—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using at least a triple pressure main column system in a double column flowsheet with a high pressure pre-rectifier
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04296—Claude expansion, i.e. expanded into the main or high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/42—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen

Definitions

  • the present invention relates to a method and a system for the cryogenic separation of air according to the preambles of the independent claims.
  • Air separation plants have column systems that can conventionally be designed, for example, as two-column systems, in particular as classic Linde double-column systems, but also as three- or multi-column systems.
  • columns for obtaining nitrogen and / or oxygen in the liquid and / or gaseous state i.e. the columns for nitrogen-oxygen separation
  • columns for obtaining further air components in particular the noble gases krypton, xenon and / or argon.
  • the terms “rectification” and “distillation” as well as “column” and “column” or combined terms are used synonymously.
  • the columns of the column systems mentioned are operated at different pressure levels.
  • Known double column systems have a so-called high pressure column (also referred to as a pressure column, medium pressure column or lower column) and a so-called low pressure column (also referred to as an upper column).
  • the high pressure column is typically operated at a pressure level of 4 to 7 bar, in particular approx. 5.3 bar.
  • the low-pressure column is operated at a pressure level of typically 1 to 2 bar, in particular about 1.4 bar. In certain cases, higher pressure levels can also be used in both columns.
  • the pressures given here and below are absolute pressures at the top of the respective columns given.
  • adapted air separation plants can be used which, in addition to the two columns explained, have an additional column which is operated at an even higher pressure, for example at 8 to 12 bar. Gaseous nitrogen can be taken as top product from this additional column and, if it is required at a corresponding pressure level, no longer has to be compressed, so that there is no corresponding compressor for compressing gaseous nitrogen.
  • the additional column is operated with a condenser-evaporator which condenses overhead gas of the additional column, so that a reflux to the additional column can be provided.
  • Air separation plants are designed (usually) based on a so-called design case with maximum product quantities. Other (imaginable) operational cases are converted based on this case. If different products are produced in the air separation plant, for example internally compressed oxygen in addition to the aforementioned pressurized nitrogen (see below for the concept of internal compression), it is often to be expected that these products will be requested in different product quantities. A corresponding scaling of the production quantities is therefore desirable.
  • a desired operating case includes the production of 100% (the maximum amount of the design case) internally compressed oxygen and approx. 75% pressurized nitrogen.
  • the setting of other product ratios is also conceivable, since the operation of the plant often deviates from the design.
  • the compressor used can be operated in a turndown mode when there is less demand or, in the case of partial recompression, switched off completely without affecting the rest of the system. This control option is not available in the air separation plants explained with an additional column in which there is no corresponding compressor.
  • the present invention therefore sets itself the task of finding solutions by means of which flexible operation can also be ensured in the air separation plants explained with an additional column.
  • Liquids and gases can be rich or poor in one or more components in the parlance used here, with “rich” for a content of at least 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99% and “poor” can mean a content of no more than 25%, 10%, 5%, 1%, 0.1% or 0.01% on a mole, weight or volume basis.
  • the term “predominantly” can match the definition of "rich”.
  • Liquids and gases can also be enriched or depleted in one or more components, these terms referring to a content in a starting liquid or a starting gas from which the liquid or the gas was obtained.
  • the liquid or the gas is "enriched” if this or this is at least 1.1 times, 1.5 times, 2 times, 5 times, 10 times 100 times or 1,000 times the content, and " depleted "if this or this contains at most 0.9 times, 0.5 times, 0.1 times, 0.01 times or 0.001 times the content of a corresponding component, based on the starting liquid or the starting gas .
  • Oxygen nitrogen
  • nitrogen argon
  • pressure range and "temperature range” to characterize pressures and temperatures, which is intended to express that corresponding pressures and temperatures in a corresponding system do not have to be used in the form of exact pressure or temperature values to realize the inventive concept.
  • pressures and temperatures typically move in certain ranges, for example ⁇ 1%, 5%, 10% or 20% around a mean value.
  • Corresponding pressure ranges and temperature ranges can be in disjoint areas or in areas that overlap one another.
  • pressure ranges include, for example, unavoidable or expected pressure losses.
  • the values specified in bar for the pressure ranges are absolute pressures.
  • expansion machines are typically understood to mean known turboexpander (also referred to as “turbines” for short). These expansion machines can in particular also be coupled to compressors. These compressors can in particular be turbo compressors. A corresponding combination of turbo expander and turbo compressor is typically also referred to as a “turbine booster”.
  • turbine booster the turbo-expander and the turbo-compressor are mechanically coupled, the coupling being able to take place at the same speed (for example via a common shaft) or at different speeds (for example via a suitable transmission gear).
  • compressor is used here in general.
  • a “main air compressor” is characterized by the fact that it compresses all of the air that is fed to the air separation plant and separated there. In contrast, in one or more optionally provided further compressors, for example booster compressors, only a portion of this air that has already been previously compressed in the main air compressor is further compressed.
  • the “main heat exchanger” of an air separation plant represents the heat exchanger in which at least the major part of the air supplied to the air separation plant and broken down there is cooled. This takes place at least partly in countercurrent to the material flows that are discharged from the air separation plant. Such “diverted” material flows or also “products” are fluids in the parlance used here, which no longer participate in system-internal cycles, but are permanently withdrawn from them.
  • a “heat exchanger” for use in the context of the present invention can be designed in a manner customary in the art. It is used for the indirect transfer of heat between at least two fluid flows, for example a countercurrent to one another, for example a warm compressed air flow and one or more cold fluid flows or a cryogenic liquid air product and one or more warm or warmer, but possibly also cryogenic fluid flows.
  • a heat exchanger can be formed from a single or several parallel and / or serially connected heat exchanger sections, e.g. from one or more plate heat exchanger blocks. It is, for example, a plate heat exchanger (plate fin heat exchanger).
  • Such a heat exchanger has “passages” which are designed as separate fluid channels with heat exchange surfaces and which are connected in parallel and, in particular, separated by other passages, to form “passage groups”.
  • a heat exchanger is characterized by the fact that heat is exchanged between two mobile media in it at a time, namely at least one fluid flow to be cooled and at least one fluid flow to be heated.
  • a “condenser evaporator” is a heat exchanger in which a first, condensing fluid flow enters into indirect heat exchange with a second, evaporating fluid flow.
  • Each condenser evaporator has a liquefaction space and an evaporation space.
  • the liquefaction and evaporation spaces have liquefaction and evaporation passages.
  • the condensation (liquefaction) of the first fluid flow is carried out in the liquefaction space, and the evaporation of the second fluid flow in the vaporization space.
  • the evaporation and the liquefaction space are formed by groups of passages which are in a heat exchange relationship with one another.
  • the axes of the two components do not have to be exactly perpendicular, but can also be offset from one another, especially if one of the two components, for example a rectification column or a column part with a smaller diameter, is to have the same distance from the sheet metal jacket of a coldbox as another with a larger one Diameter.
  • the present invention proposes a method for the low-temperature separation of air, in which an air separation plant is used with a column system which has a first column, a second column and a third column.
  • the first to third columns in the air separation plant according to the invention result from the extension of a classic double column system known from the prior art to include an additional column operated at a higher pressure than the conventionally present high pressure column.
  • the first column can be provided in particular structurally separate from the second and third column, wherein the second and third column can in particular be part of a double column and by means of a corresponding one Condenser evaporator, the so-called main condenser, can be in heat-exchanging connection with one another.
  • the second and third column can in particular be part of a double column and by means of a corresponding one Condenser evaporator, the so-called main condenser, can be in heat-exchanging connection with one another.
  • main condenser the so-called main condenser
  • the second and third columns which are designed as part of a double column, can also be supplemented by an additional column in a corresponding multiple column system, or the second and third columns can be provided as separate columns.
  • the main capacitor mentioned can be provided as an internal or external main capacitor, as is basically known from the prior art. If an internal main condenser is used, this is at least partially submerged in a sump liquid in the sump of the third column and an overhead gas to be condensed from the second column is passed through a condensation chamber of the main condenser.
  • a fourth column can be provided, which can be used in particular to extract argon or discharge argon from a gas mixture that is withdrawn from the third column.
  • the fourth column can in particular be a conventional crude argon column of a known arrangement with crude and pure argon column, but it can also be a modified argon column from which argon is withdrawn in the pure state below the top without using an additional pure argon column.
  • Other variants are also possible within the scope of the present invention.
  • Corresponding configurations are possible in combination with all configurations of the invention which are specified below, but are not explained repeatedly for reasons of clarity.
  • a bottom liquid is formed in each of the first column, the second column and the third column.
  • the bottom liquid of the second column is formed in particular with a higher oxygen content than the bottom liquid of the first column and the bottom liquid of the third column is formed with a higher oxygen content than the bottom liquid of the second column.
  • the oxygen content of the bottom liquid of the first column can be 30 to 40%, in particular about 36% and the oxygen content of the bottom liquid of the second column can be about 40 to 60%, in particular about 47%, lie.
  • the oxygen content of the bottom liquid of the third column can be in particular from 90 to 99.9 mol%, in particular around 95 mol%.
  • the first column is operated in a first pressure range
  • the second column is operated in a second pressure range below the first pressure range
  • the third column is operated in a third pressure range below the second (and thus also the first) pressure range.
  • the first pressure range can in particular be 8 to 12 bar, for example approximately 9.0 bar. This can also be the product pressure of the pressurized nitrogen provided in the context of the present invention.
  • the second pressure range is advantageously 4 to 6 bar, in particular approx. 5.5 bar
  • the third pressure range is advantageously 1 to 2 bar, in particular approx. 1.4 bar.
  • the pressure specifications here denote absolute pressures at the head of corresponding columns.
  • the second and third columns are thus operated in the context of the present invention, as already mentioned above, in pressure ranges in which the high and low pressure columns conventionally used in air separation plants are also operated.
  • the first column is operated in a higher pressure range.
  • the third column is fed with bottom liquid from the first column and bottom liquid from the second column.
  • the bottom liquid of the first column it can be a portion of the bottom liquid that is withdrawn from the first column as a whole.
  • the bottom liquid of the second column can in particular be completely transferred into the third column.
  • the bottom liquids transferred into the third column are in particular supercooled beforehand, as also explained below.
  • a first overhead gas condensate is formed from overhead gas from the first column and a second overhead gas condensate is formed from overhead gas from the second column, and further overhead gas from the first column is discharged in gaseous form from the air separation plant.
  • the latter is the initially mentioned, in particular not further compressed nitrogen.
  • the present invention particularly addresses the problem that no corresponding compressor is available and controllable.
  • This pressurized nitrogen has, in particular, a nitrogen content of 95 to 99.9999 mol%.
  • the air separation plant used according to the invention can be distinguished in particular by the use of a so-called combination compressor, which is particularly advantageous in structural terms.
  • This advantage arises in particular when moderate oxygen product pressures of, for example, 6 to 9 bar are used in the internal compression and therefore the corresponding throttle flow in the main heat exchanger does not have to be compressed excessively, i.e. only to, for example, 15 to 21 bar. Therefore, only one compressor stage is required for a booster (Booster Air Compressor, BAC) and this can be combined particularly advantageously with the main air compressor.
  • Booster Air Compressor boosting Air Compressor
  • the air separation plant used can be designed without pre-cooling the air from the inlet to the molecular sieve adsorber. Due to the relatively high process pressure of approx. 9 bar, this air flow has relatively little water and additional air pre-cooling (e.g. by means of a process air cooler in combination with an evaporative cooler or a refrigeration machine, etc.) is not absolutely necessary.
  • a process air cooler is shown downstream of the main air compressor; In many cases, however, this can be replaced by a simple aftercooler.
  • Liquid transfer pumps can largely be dispensed with in the process.
  • there are advantageously no transfer pumps for cryogenic liquids i.e. all liquid flows are fed into the other pressure chambers with the help of (own) process pressures.
  • the return pump used for liquid nitrogen is not a transfer pump, but rather a process pump (the liquid is deliberately pumped to a significantly higher pressure, since the pressures in the two columns are very different).
  • the further top gas of the first column which is discharged in gaseous form from the air separation plant, that is, corresponding pressurized nitrogen, is in one first operating mode in a first amount per time unit and in a second operating mode in a second amount per time unit, which is below the first amount per time unit, discharged from the air separation plant.
  • first operating mode part of the second overhead gas condensate is also transferred into the first column, and in the second operating mode a part of the first overhead gas condensate is transferred into the first column.
  • an air separation plant is designed for the so-called design case, i.e. the optimization of the number of separation stages in the columns and the purity to be set at the top, especially of the second column, depend on the operating case with maximum production quantities.
  • the reflux liquid to the first column or the part of the top gas that is used to provide the first top gas condensate is in (or very close to) thermodynamic equilibrium with the pressure product to be discharged from the same separating tray, i.e. the further top gas, which is gaseous is discharged from the air separation plant. If less is required of the corresponding printed product, it is to be expected that the energy consumption of the system will also be reduced. However, this could not be confirmed in the conventional process execution. However, such an advantage can be achieved in the present invention.
  • the measures proposed according to the invention include that the two columns working under relatively high pressures (namely the first and second columns) optimally share the overhead gas condensates with one another depending on the required product amount of pressurized nitrogen (namely by, as already explained above, in the first operating mode higher pressure nitrogen demand part of the second overhead gas condensate is transferred into the first column and in the second operating mode with lower pressure nitrogen demand part of the first overhead gas condensate is transferred into the first column).
  • the measures proposed according to the invention also develop their advantages because the oxygen yield in a corresponding system in the design case is good, but not necessarily “ideal” (the air factor is around 5.0, with the "air factor” being the ratio of the amount of Oxygen product to the amount of air used, expressed in molar or mass fractions, is to be understood). Therefore it should be possible to reduce the amount of feed air by reducing the amount of pressurized nitrogen.
  • the amount of air used in the first operating mode is more advantageously 1.03 to 1.2 times as much as in the second operating mode.
  • the liquid reflux in this column should also be reduced, since otherwise the optimum reflux ratio (F / D approx. 0.6) is shifted.
  • the amount can be reduced in such a way that the excess “first” top gas condensate from the first column is introduced into the second column.
  • the present invention particularly comprises a switchover between the conveying directions.
  • the reduction in the flow rate of the second overhead gas condensate in the first column or the introduction of the first overhead gas condensate in the second column leads to a sharp increase in the F / D (liquid / vapor) ratio in this second column with a mathematically the same purity at the top . If, on the other hand, the purity at the top of the second column is adjusted so that the F / D ratio is close to the optimum for the number of trays "installed" in the second column, a higher amount of liquid can flow from the second column into the third column are transferred, so that the F / D ratio in a section of the third column can be improved (increased). In this way, oxygen can be washed out better in the third column and the oxygen yield is noticeably increased. Sufficient separation stages must be provided for this.
  • no part of the first overhead gas condensate is transferred into the second column in the first operating mode and no part of the second overhead gas condensate is transferred into the first column in the second operating mode.
  • This smaller amount can for example be less than 10% of the amount in the second operating mode.
  • part of the second overhead gas condensate can also be transferred into the first column both in the first and in the second operating mode, and in this case too, comparable to the previous one, in the second Operating mode a significantly smaller amount is transferred into the first column.
  • This smaller amount can also be, for example, less than 10% of the amount in the first operating mode.
  • an amount of the second overhead gas condensate transferred in the first operating mode into the first column and an amount of the first overhead gas condensate transferred in the second operating mode into the second column can dynamically be added to the amount of the further overhead gas from the first column, which is discharged in gaseous form from the air separation plant.
  • the first and the second operating mode therefore do not have to be static.
  • dynamic transition states between the first and the second operating mode can be provided.
  • the first amount per unit of time can in particular be 1.1 to 2 times the second amount per unit of time. In one example, the first amount per unit of time can be approximately 1.4 times the second amount per unit of time, for example. In a more specific example, the first amount per unit of time can be approximately 15,000 standard cubic meters per hour (Nm 3 / h) and the second amount per unit of time is approximately 11,000 Nm 3 / h.
  • the part of the second overhead gas condensate which is transferred to the first column in the first operating mode can be transferred to the first column in this first operating mode in an amount per unit of time that is, for example, 1.5 to 10 times an amount per unit of time in which the part of the first overhead gas condensate is transferred into the first column in the second operating mode.
  • this value can be 2.7 times, for example, in the more specific example approx. 2,000 Nm 3 / h of second overhead gas condensate is transferred to the first column in the first operating mode and approx. 750 Nm 3 / h in the second operating mode first overhead gas condensate in the second.
  • the first overhead gas condensate can in particular be formed in a first condenser evaporator, by means of which further bottom liquid from the first column and / or liquefied compressed air can be evaporated.
  • This first condenser-evaporator can in particular be used as a top condenser on the first column.
  • An evaporation pressure in the first top condenser can in particular lie between the first and the second pressure range, a condensation pressure lies in particular in the first pressure range.
  • Gas formed by the evaporation in the first condenser-evaporator and / or liquid remaining during the evaporation can be fed into the second column within the scope of the present invention. It is also possible to form the second overhead gas condensate in a further condenser evaporator, by means of which bottom liquid of the third column is evaporated.
  • This further condenser evaporator can in particular be designed analogously to a conventional main condenser in a double column of an air separation plant and as an internal, in particular multi-stage, bath evaporator.
  • an internally compressed oxygen product is also provided.
  • the bottom liquid of the third column is subjected to a pressure increase to a product pressure, converted into a gaseous or supercritical state at the product pressure, and discharged from the air separation plant in the gaseous or supercritical state.
  • the product pressure can in particular be 6 to 8 bar, in particular approx. 7 bar.
  • a production quantity of the internally compressed oxygen product is the same, in particular in the first and second operating mode, or does not differ by more than, for example, approximately 5%.
  • the first overhead gas condensate is advantageously formed with a content of 1 to 3 mol-ppm oxygen, in particular approx. 1.9 mol-ppm oxygen.
  • the second overhead gas condensate is advantageously formed in the first operating mode with a content of 2 to 5 mol-ppm oxygen, in particular approx. 4.3 mol-ppm oxygen, and the second overhead gas condensate is advantageously formed in the second operating mode with a content of 0.1 up to 1 mol-ppm oxygen, in particular about 0.6 mol-ppm oxygen.
  • the first overhead gas condensate can be formed with a content of Y mol-ppm oxygen
  • the second overhead gas condensate then in the first operating mode in particular with a content of 1.2 ⁇ Y to 4.0 ⁇ Y mol-ppm oxygen and in that second mode of operation with a content of 0.1 ⁇ Y to 0.8 ⁇ Y mol-ppm oxygen is formed.
  • Y can be in the range given above.
  • This reflux is, in particular, further fluid from the second column with which the third column is fed.
  • This fluid can be withdrawn as a side stream from the second column, expanded and fed in liquid form as reflux into the third column in an upper region, in particular above the uppermost separating tray.
  • any mutual temperature control of substance flows can take place.
  • the further fluid from the second column, with which the third column is fed, the bottom liquid of the first column, with which the third column is fed, the bottom liquid of the second column, with which the third column is fed, and top gas of the third Column, which is discharged from the air separation plant are subjected to a heat exchange with one another.
  • the further bottom liquid of the first column can likewise be subjected to the heat exchange and discharged in liquid form from the air separation plant.
  • the first column is fed with cooled, gaseous compressed air, which is advantageously re-compressed to a first proportion in a turbine booster and then expanded in the turbine booster.
  • a second component is not compressed in the turbine booster, but only cooled down in the main heat exchanger when there is a corresponding inlet pressure.
  • the part of the second overhead gas condensate which is transferred into the first column in the first operating mode is pressurized by means of a pump and conveyed into the first column.
  • a pump is used here which has a pump bypass provided with a valve (in particular back to the point where the second overhead gas condensate is withdrawn at the top of the second column).
  • This pump bypass is originally intended, for example for commissioning or for regulating the pressure or volume of the pump (especially in the event of severe underload).
  • the flow through the bypass is in one direction, namely to the top of the second column.
  • the part of the first top gas condensate which is fed into the second column can now flow to the second column via this pump bypass.
  • the embodiment of the invention just explained is particularly advantageous in practice because in this way the invention can be implemented without providing a separate line from the first to the second column for conducting the first overhead gas condensate.
  • the first overhead gas condensate can be fed in the opposite direction to the pump and then over the bypass into the second column via the same line through which the second overhead gas condensate flows in the first operating mode.
  • the invention can be implemented purely in terms of control technology in an air separation plant that already has a corresponding line with a pump.
  • the present invention also extends to an air separation plant, the features of which are expressly referred to in the corresponding independent patent claim.
  • an air separation plant is set up to carry out a method, as has been explained above in different configurations, and this has means set up in each case for this purpose.
  • express reference is made to the explanations relating to the method according to the invention.
  • Air separation plants 100, 200 are shown, each of which corresponds to embodiments of the present invention insofar as they fall under the scope of the claims.
  • the air separation plants 100, 200 are equipped with a column system, each of which is designated as a whole by 10.
  • the column systems 10 each have a first column 11, a second column 12 and a third column 13.
  • the second column 12 and the third column 13 are each designed as parts of a double column of a basically known type.
  • the first column 11 is formed separately from the second column 12 and the third column 13.
  • the first column 11 is equipped with an overhead condenser 111 which is used to condense overhead gas from the first column 11 and thus to provide the overhead gas condensate previously referred to as “first overhead gas condensate”.
  • Bottom liquid from the first column 12 and cooled compressed air are fed into the top condenser 111 (see below).
  • the second column 12 and the third column 13 are in heat-exchanging connection with one another via an internal condenser-evaporator 121, the so-called main condenser.
  • the main condenser 121 serves on the one hand to condense an overhead gas of the second column 12 and thus to provide the "second overhead gas condensate" and on the other hand to evaporate a bottom liquid of the third column 13.
  • the second column 12 and the third column 13 can also be formed separately.
  • the main capacitor 121 can alternatively also be formed on the outside.
  • Various types of condenser evaporators can be used as the main condensers 121.
  • a feed air stream a is sucked in from the atmosphere generally designated A here by means of a main air compressor 101 via a filter, which is not separately designated and shown in hatching, then cooled in an aftercooler, likewise not designated separately, and fed to a direct contact cooler 102, which is supplied with cooling water W is operated.
  • the feed air flow is in an adsorption device 103 in many cases in the Freed from water and carbon dioxide as described in the literature.
  • the correspondingly treated and thus purified feed air flow is then divided into two partial flows b and c.
  • Partial flow b is recompressed in a compressor stage 104 integrated with main air compressor 101 and then divided into two partial flows d and e, with partial flow d being recompressed in a turbine booster 105, then partially cooled in main heat exchanger 106, expanded in turbine booster 105 and into the first column 11 is fed in.
  • the substream e is only cooled in the main heat exchanger, liquefied due to the higher pressure than the substream c, and fed into the top condenser 111.
  • the substream c is passed through the main heat exchanger 106 and, after cooling, fed in gaseous form together with the substream d into the first column 11.
  • Bottom liquid from the first column 11 is withdrawn from this and divided into two substreams f and g.
  • the substream f is fed into the top condenser 111, the substream g after cooling in a subcooling countercurrent 107 into the third column 13 (cf. link 1).
  • Top gas from the top of the first column 11 is heated in the form of a substream h in the main heat exchanger 106 and discharged from the air separation plant 100, 200 as nitrogen product H under pressure. Further overhead gas is condensed in the overhead condenser 111 and thus used as material flow k to provide the first overhead gas condensate. A portion of the condensate formed can also be discharged as liquid nitrogen product K.
  • Bottom liquid is formed in the second column 12 and is subcooled in the form of a material flow m in the subcooling countercurrent 107 and then fed into the third column 13.
  • Top gas of the second column can be heated and discharged in the form of a stream n, for example to provide seal gas N. Further overhead gas is used in the form of a stream o to provide the second overhead gas condensate.
  • a side stream from the second column (cf. link 1) is expanded into the third column 13 after subcooling in the subcooling countercurrent 107 from the second column 12.
  • Bottom liquid of the third column 13 can be withdrawn from this in the form of a stream p, liquid pressure increased in a pump 108, evaporated and provided as an internally compressed oxygen product P. A part can also follow Subcooling can be provided as liquid oxygen product X. Impure nitrogen can be withdrawn from the top of the third column 13 in the form of a stream q, heated in the subcooling countercurrent 107, further heated in the main heat exchanger 106 and used, for example, as a regeneration gas.
  • first operating mode part of the second overhead gas condensate is transferred from the second column 12 into the first column 11
  • second operating mode a part of the first overhead gas condensate is transferred from the second column 12 transferred into the first column 11.
  • a pump 109 and a valve which is not specifically designated, are present in the air separation plant 100, which are controlled via a control unit 50, which also serves to initiate the first and second operating modes.
  • a pump bypass 201 is used in the system 200 to implement the first and second operating modes.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Power Engineering (AREA)
  • Separation By Low-Temperature Treatments (AREA)
EP19020450.3A 2019-08-01 2019-08-01 Procédé et installation de séparation d'air à basse température Pending EP3771873A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19020450.3A EP3771873A1 (fr) 2019-08-01 2019-08-01 Procédé et installation de séparation d'air à basse température

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19020450.3A EP3771873A1 (fr) 2019-08-01 2019-08-01 Procédé et installation de séparation d'air à basse température

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EP3771873A1 true EP3771873A1 (fr) 2021-02-03

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3280574A (en) * 1960-10-14 1966-10-25 Linde Ag High pressure pure gas for preventing contamination by low pressure raw gas in reversing regenerators
EP1653183A1 (fr) * 2004-10-12 2006-05-03 Air Products And Chemicals, Inc. Procédé et dispositif pour la séparation cryogénique d'air
EP2235460A2 (fr) * 2008-01-28 2010-10-06 Linde Aktiengesellschaft Procédé et dispositif de séparation de l'air à basse température
WO2014146779A2 (fr) * 2013-03-19 2014-09-25 Linde Aktiengesellschaft Procédé et dispositif de production d'azote gazeux sous pression

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3280574A (en) * 1960-10-14 1966-10-25 Linde Ag High pressure pure gas for preventing contamination by low pressure raw gas in reversing regenerators
EP1653183A1 (fr) * 2004-10-12 2006-05-03 Air Products And Chemicals, Inc. Procédé et dispositif pour la séparation cryogénique d'air
EP2235460A2 (fr) * 2008-01-28 2010-10-06 Linde Aktiengesellschaft Procédé et dispositif de séparation de l'air à basse température
WO2014146779A2 (fr) * 2013-03-19 2014-09-25 Linde Aktiengesellschaft Procédé et dispositif de production d'azote gazeux sous pression

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Industrial Gases Processing", 2006, WILEY-VCH, article "Cryogenic Rectification"

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