Patent Application
20250052493
The present invention relates to a method for the cryogenic separation of air and an air separation plant according to the respective preambles of the independent patent claims.
The production of air products in the liquid or gaseous state by cryogenic separation of air in air separation plants is known and described, for example, in H.-W. Häring (editor), Industrial Gases Processing, Wiley-VCH, 2006, in particular Section 2.2.5, “Cryogenic Rectification.”
Air separation plants have rectification column arrangements which can be designed differently. In addition to rectification columns for obtaining nitrogen and/or oxygen in the liquid and/or gaseous state, that is to say rectification columns for nitrogen-oxygen separation which can be combined in particular in a known double column, rectification columns for obtaining other air components, in particular noble gases, or pure oxygen, can be provided.
The rectification columns of typical rectification column arrangements are operated at different pressure levels. Known double columns have a so-called pressure column (also referred to as a high-pressure column, medium-pressure column or lower column) and a so-called low-pressure column (upper column). The high-pressure column is typically operated at a pressure level of 4 to 7 bar, in particular about 5.3 bar; the low-pressure column on the other hand is operated at a pressure of typically 1 to 2 bar, in particular about 1.4 bar. In certain cases, even higher pressure levels may be used in these rectification columns. The pressures indicated here and below are absolute pressures at the top of the respective indicated rectification columns.
In order to extract argon, air separation plants with raw and pure argon columns can be used. An example is illustrated in Häring (see above) in
The raw argon column serves substantially to separate off the oxygen from the gas drawn off from the low-pressure column. The oxygen separated off in the raw argon column or a corresponding oxygen-rich fluid can be returned to the low-pressure column in liquid form. A gaseous fraction which remains in the raw argon column during the separation and contains substantially argon and nitrogen is further separated in the pure argon column to obtain pure argon. The raw and the pure argon column have top condensers which can be cooled in particular with a part of an oxygen-enriched, nitrogen-depleted liquid withdrawn from the high-pressure column, which partially evaporates during this cooling. This is also the case in the context of the present invention. The gas phase formed during partial evaporation and the corresponding remaining liquid are also fed into the low-pressure column at different feed points, the choice of which is explained below.
The oxygen or the oxygen-rich fluid from the raw argon column is typically fed back from the high-pressure column into the low-pressure column multiple theoretical or practical plates below the feed points for the partially evaporated liquid used for cooling.
An object of the present invention is to provide means for improving the operation of an air separation plant with an argon recovery system comprising a raw argon column and a pure argon column.
Against this background, the present invention proposes a method for the low-temperature separation of air and an air separation plant with the features of the respective independent patent claims. Each of the embodiments are the subject matter of the dependent claims and of the description below.
In the following, some terms used in describing the present invention and its advantages, as well as the underlying technical background, will first be explained in more detail.
The devices used in an air separation plant are described in the cited technical literature, for example in Häring, Section 2.2.5.6, “Apparatus.” Unless the following definitions differ, reference is therefore explicitly made to the cited technical literature with respect to terminology used within the framework of the present application.
In this case, a “condenser evaporator” refers to a heat exchanger in which a first, condensing fluid stream enters into indirect heat exchange with a second, evaporating fluid stream. Each condenser evaporator has a liquefaction chamber and an evaporation chamber. The liquefaction and evaporation chambers have liquefaction or evaporation passages.
Condensation (liquefaction) of the first fluid stream is carried out in the liquefaction chamber, and evaporation of the second fluid stream in the evaporation chamber. The evaporation and liquefaction chambers are formed by groups of passages, which are in a heat-exchanging relationship with one another. Condenser evaporators are also referred to as “top condenser” and “bottom evaporator” according to their function, wherein a top condenser is a condenser evaporator in which head gas of a rectification column is condensed, and a bottom evaporator is a condenser evaporator in which bottom liquid of a rectification column is evaporated. However, the bottom liquid can also be evaporated in a top condenser, for example as used in the context of the present invention.
In particular, what is referred to as the main condenser, which connects a high-pressure column and a low-pressure column of an air separation plant in a heat-exchanging manner, is designed as a condenser evaporator. The main condenser or other condenser evaporator can be designed in particular as single-level or multi-level bath evaporators, in particular as a cascade evaporator (as described, for example, in EP 1 287 302 B1) but also as a falling-film evaporator. A corresponding condenser evaporator can be formed, for example, by a single heat exchanger block or by multiple heat exchanger blocks arranged in a common pressure vessel.
In a “forced-flow” condenser evaporator or a condenser evaporator with forced flow on the evaporation side, which can also be used within the scope of the present invention, a liquid stream is pressed by means of its own pressure through the evaporation chamber and partly evaporated there. (“Forced-flow” evaporators are sometimes also referred to as “once-through evaporators.”) This pressure is generated, for example, by a liquid column in the supply line to the evaporation chamber, which liquid column results from the corresponding positioning of a liquid reservoir. In this case, the height of this liquid column at least corresponds to the pressure loss in the evaporation chamber. The gas or gas-liquid mixture leaving the evaporation chamber, i.e., a two-phase flow, is passed directly to the next method step or to a downstream device in a once-through/forced-flow condenser evaporator and, in particular, is not introduced into a liquid bath of the condenser evaporator, from which the remaining liquid proportion would be drawn in again, as is the case, for example, in a conventional bath evaporator operating on the basis of the known thermosiphon effect.
Fluids, that is to say liquids and gases can, in the terminology used herein, be rich or low in one or more components, wherein “rich” can refer to a content of at least 50%, 75%, 90%, 95%, 99%, 99.5%, 99.9% or 99.99%, and “low” can refer to a content of at most 50%, 25%, 10%, 5%, 1%, 0.1% or 0.01% on a molar, weight or volume basis. The term “predominantly” can correspond to the definition of “rich.” Fluids can further be enriched or depleted by one or more components, wherein these terms relate to a content in a starting fluid from which the fluid was obtained. The fluid is “enriched” if it contains 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 it 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 fluid. If, by way of example, reference is made here to “oxygen” or “nitrogen,” this is also understood to mean a fluid that is rich in oxygen or nitrogen but need not necessarily consist exclusively thereof.
The present disclosure uses the terms “pressure range” and “temperature range” to characterize pressures and temperatures, which means that corresponding pressures and temperatures in a corresponding plant do not have to be used in the form of exact pressure or temperature values in order to realize the inventive concept. For example, there are different pressures at different positions within the pressure and low-pressure column, but they are within a certain pressure range, also referred to as the operating pressure range. Corresponding pressure ranges and temperature ranges can be disjoint ranges or ranges that overlap one another.
Absolute and/or relative spatial indications used below, such as in particular “over,” “under,” “above”, “below”, “next to” and “next to one another,” refer in particular here to the spatial orientation of the correspondingly designated elements of an air separation plant, for example rectification columns, sub-columns of multi-part rectification columns, or rectification regions of rectification columns in normal operation. An arrangement of two elements “one above the other” is understood here in particular to mean that the upper end of the lower of the two elements is located at a lower or the same geodetic height as the lower end of the upper of the two elements, and the projections of the two elements overlap in a horizontal plane. In particular, the two elements can be arranged exactly one above the other, that is to say the vertical center axes of the two elements run on the same vertical straight line. An arrangement “next to one another” is to mean in particular that the projections of the two elements do not overlap in a horizontal plane. In the case of a rectification column designed in multiple parts, terms such as “functionally below” or “functionally above” refer to the arrangement of rectification regions or sub-columns that they would have if the rectification column had a single-part design.
The present invention is based in particular on the realization that prior art air separation plants with raw and pure argon columns, the top condensers of which are cooled in the manner described at the outset, have two major disadvantages:
The liquids remaining after partial evaporation of the cooling fluids in these top condensers are traditionally fed into the low-pressure column at different points or stages. This is correct from a thermodynamic point of view because the composition of the two liquids is quite different. What is not correct (from a thermodynamic point of view) is that the gases formed during partial evaporation in these top condensers are traditionally mixed despite the noticeable difference in composition.
Furthermore, the oxygen-enriched liquid used for cooling in the top condensers of the raw and pure argon column and drawn off from the pressure column is throttled into the evaporation chamber of the top condenser of the raw argon column. A certain proportion evaporates as what is known as flash gas. The proportion of vapor in the throttled flow, i.e., the proportion of flash gas, is typically approximately 10%. The composition of the vapor differs significantly from the composition of the liquid phase (due to the equilibrium conditions). The liquid phase is almost completely vaporized in the top condenser of the raw argon column, wherein the evaporation gas formed here mixes with the flash gas. This results in a mixture of two gas flows with different compositions, which is thermodynamically incorrect, as this mixture must then be further separated.
The present invention eliminates these disadvantages by providing a method for the cryogenic separation of air, in which method an air separation unit with a rectification column arrangement is used, which plant has a pressure column, a low-pressure column, a raw argon column and a pure argon column.
Using a first proportion of an oxygen-enriched liquid from the pressure column, a first liquid pressure flow is formed, which is expanded while a first flash gas is obtained and a first low-pressure liquid remains.
Using a second proportion of the oxygen-enriched liquid from the pressure column, a second liquid pressure flow is formed, which is expanded while a second flash gas is obtained and a second low-pressure liquid remains.
The two proportions can be expanded together in the same valve or separately in a separate valve.
The raw argon column is operated using a first head gas condensation arrangement in which head gas of the raw argon column is subjected to condensation with partial evaporation of a first cooling fluid provided using the first low-pressure liquid or a part thereof.
The pure argon column is operated using a second head gas condensation arrangement in which head gas of the pure argon column is subjected to condensation with partial vaporization of a second cooling fluid, which is provided using the second low-pressure liquid or a part thereof.
A first evaporation gas formed during the partial evaporation of the first cooling fluid or a part thereof and a first excess liquid remaining after the partial evaporation of the first cooling fluid or a part thereof are fed into the low-pressure column.
A second evaporation gas formed during the partial evaporation of the second cooling fluid or a part thereof and a second excess liquid remaining after the partial evaporation of the second cooling fluid or a part thereof are fed into the low-pressure column.
The term “evaporation gas” refers to the evaporated proportion formed by the heat transfer from the respective head gases of the raw and pure argon column in the head gas condensation arrangements or condenser evaporators. Any remaining liquid residue is referred to here as an “excess liquid.” In contrast to the term “evaporation gas,” the term “flash gas” is used to describe the gas or vapor proportion which is only formed by expansion.
According to the invention, it is provided that the first evaporation gas or the part thereof fed into the low-pressure column is partially or completely fed into the low-pressure column in a first feed-in region.
In contrast, according to the invention, the second evaporation gas or the part thereof fed into the low-pressure column is partially or completely fed into the low-pressure column in a second feed-in region.
Thus, according to the invention, the two gas phases formed in the respective top condensers are fed separately into the low-pressure column at different and respectively suitable positions. This avoids the disadvantages described above, which result from the conventional common feed-in in view of the different compositions of the two evaporation gases.
According to the invention, the second excess liquid or the part thereof fed into the low-pressure column is partially or completely fed into the low-pressure column in the second feed-in region, i.e., at a position at which the second evaporation gas is also fed in.
In one embodiment of the invention, the first flash gas or a part thereof can be partially or completely fed into the low-pressure column in the second feed-in region, separately from the first evaporation gas. In this way, the disadvantages of the prior art also mentioned, which result from the common feed-in carried out there in view of the different gas compositions, can be overcome.
According to the invention, the first feed-in region is located 5 to 25 theoretical plates below the second feed-in region, and the first and second feed-in regions are each regions which do not comprise any separating devices and are each arranged between an upper separating region arranged above and a lower separating region arranged below. Preferably, the upper separating region of the first (lower) feed-in region is also the lower separating region of the second (upper) feed-in region, i.e., it lies exactly between the two feed-in regions. The separating regions are filled with material exchange elements and are preferably designed as packing portions.
In other words, according to the invention, the evaporation gas from the head gas condensation arrangement of the pure argon column is introduced into the low-pressure column, in particular at the same separation stage as the residual liquid remaining here. Since both flows are in thermodynamic equilibrium, no additional liquid distributor is required. Both flows can be fed into the low-pressure column in the form of a two-phase flow via a two-phase nozzle, for example. This results in a significant increase in the argon yield. There is no increase in the energy requirement due to an improvement in oxygen recovery.
For flash gas separation after expansion in separate valves, two separate phase separation devices are provided in a first variant of the invention, for example a simple phase separator for the first flash gas (first phase separation) and/or the evaporation chamber of the second head gas condensation arrangement for the second flash gas.
By separately flashing the liquid pressure flow from the pressure column, which liquid pressure flow is used for cooling in the first head gas condensation arrangement of the raw argon column while forming first flash gas and mixing the first flash gas with the second evaporation gas formed in the second head gas condensation arrangement of the pure argon column, further advantages are achieved, which consist in particular of an additional increase in the argon yield.
In particular, the expansion upstream of the phase separation can take place from the operating pressure level of the pressure column to an operating pressure level of the low-pressure column. Different approaches can be taken with regard to the design of the phase separation, which are explained below.
In a second variant of the invention, the first and second liquid pressure flows are expanded in a common valve and jointly subjected to phase separation, preferably in the evaporation chamber of the second head gas condensation arrangement, which also acts as a phase separator. The first cooling fluid is then drained from the liquid phase of the evaporation chamber. The first flash gas is drawn off together with the second evaporation gas from the evaporation chamber of the second head gas condensation arrangement.
In both variants of the invention, the first flash gas can be fed into the low-pressure column separately from the first evaporation gas in the second feed-in region, wherein in particular the first flash gas is transferred unthrottled into the low-pressure column (12) after it has been provided in the first phase separation.
As mentioned above, the first evaporation gas or a part thereof together with the first excess liquid or a part thereof can be fed as a first two-phase flow into the low-pressure column in the first feed-in region.
In a particularly advantageous embodiment of the invention, one or more “forced-flow” condenser evaporators of the type described can be used in the first head gas condensation arrangement. Reference is made in this context to the explanations above. In particular, the first low-pressure liquid or a part thereof as the first cooling fluid is thus forced through one or more condenser evaporators, which is or are formed as part of the first head gas condensation arrangement, and is thereby subjected to partial evaporation to form the first evaporation gas and the first excess liquid. In this case, “forced through” is defined as feeding into the evaporation chamber under pressure, for example by means of a pipeline.
Advantageously, the forced guidance is caused by the pressure of the liquid column. The first low-pressure liquid or the part thereof which is forcibly fed through the one or more condenser evaporators is advantageously held in a reservoir which is geodetically arranged above one or more feed-in positions in the one or more condenser evaporators.
Particularly preferably, a “once-through” arrangement is used in which the first evaporation gas and the first excess liquid are discharged from the condenser evaporator as the first two-phase flow without returning the first excess liquid or a part thereof into the one or more condenser evaporators.
Regardless of the specific embodiment of the other features, the first flash gas can be transferred unthrottled to the low-pressure column after being provided in the phase separation.
In a preferred embodiment of the invention, the second evaporation gas or the part thereof fed into the low-pressure column in the second feed-in region can be combined in particular with the second excess liquid or the part thereof fed into the low-pressure column in the second feed-in region to form a second two-phase flow which is fed into the low-pressure column in the second feed-in region.
In a further embodiment, the first head gas condensation arrangement can in particular have a bath evaporator with an evaporation chamber in which the phase separation is integrated, in particular as a conical installation.
In principle, the first excess liquid from the first head gas condensation arrangement can be introduced into the low-pressure column without pressure-changing measures. A pressure is then established in the evaporation chamber of the first head gas condensation arrangement which corresponds to the operating pressure of the low-pressure column plus line losses. This ensures stable operation of the system under normal conditions. In special operating situations, for example during partial load operation, the liquid argon may be undercooled to such an extent that there is a risk of the condensation passages being clogged by freezing argon (triple point of argon: 83.8 K).
According to a further aspect of the invention, when the first excess liquid and the first evaporation gas are passed together as a first two-phase flow to the low-pressure column, this problem is solved by passing the two-phase flow between the first head gas condensation arrangement and the low-pressure column through a throttle valve. By partially closing the throttle valve, the pressure and thus the temperature in the evaporation chamber can be increased in the event of an underload, thereby effectively preventing the condenser evaporator from becoming blocked due to freezing. Preferably, the valve is designed as an automatic valve; alternatively, a manual valve can be used. Overall, this results in particularly stable operation of the first head gas condensation arrangement and the raw argon column.
The throttle valve can be fully open at least temporarily during operation, in particular during normal operation.
In addition, the first excess liquid can be passed between the head gas condensation arrangement and the throttle valve and through a phase separator in which the first evaporation gas and the first excess liquid are separated from one another. The first evaporation gas is then fed into the low-pressure column separately from the first excess liquid. The pressure in the evaporation chamber is not set by the valve in the line for the first excess liquid, but by a valve in the evaporation gas line connected to the phase separator.
The liquid level in the phase separator can be measured. Depending on the measured value, the amount of first cooling fluid introduced into the first head gas condensation arrangement is preferably adjusted. Preferably, the amount of liquid in the phase separator is quantitatively controlled.
Preferably, the throttle valve, which controls the pressure in the evaporation chamber, is adjusted such that the temperature of the first cooling fluid is above the triple point temperature of argon upon entering the first head gas condensation arrangement. This inlet temperature is preferably at least 0.1 to 2.0 K, in particular 0.1 to 1.0 K above the triple point of argon.
The invention can in principle be applied to all process circuit topologies with argon recovery, regardless of the type of refrigeration or the type of product compression. These comprise, in particular, what are known as MAC/BAC or HAP processes as described, for example, in paragraphs to of EP 3 196 573 A1, methods with a nitrogen cycle as described in EP 2 235 460 A2 or in H. Hausen and H. Linde, “Tieftemperaturtechnik: Erzeugung sehr tief Temperaturen, Gasverflüssigung und Zerlegung von Gasgemischen,” 2nd ed. 1985, Springer-Verlag, Heidelberg, Section 4.5.2.2, and/or air separation plants with internal compression as described in Hausen/Linde, Section 4.5.1.6 or Häring (see above), Section 2.2.5.2, “Internal Compression.”
Regarding the features of the air separation plant likewise proposed according to the invention, reference is made expressly to the corresponding independent claim. This air separation plant is in particular configured to carry out a method as previously explained in embodiments. Reference is therefore expressly made to the above explanations regarding the process according to the invention and its advantageous embodiments.
The invention will be described in more detail below with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention.
In the figures, elements that correspond to one another structurally or functionally are denoted by identical reference signs and, for the sake of clarity, are not repeatedly explained. Explanations relating to units and unit components apply in the same way for corresponding methods and method steps.
In
Air separation plants of the type shown are often described elsewhere, for example in (see above), Industrial Gases Processing, Wiley-VCH, 2006, in particular section 2.2.5, “Cryogenic Rectification” and in conjunction with
The air separation plant 90 shown by way of example in
In the air separation plant 90, a feed air flow is sucked in and compressed by means of the main air compressor 1 via a filter (not labeled). The compressed feed air flow is supplied to the pre-cooling device 2 that is operated with cooling water. The pre-cooled feed air flow is cleaned in the cleaning system 3. In the cleaning system 3, which typically comprises a pair of adsorber vessels used in alternating operation, the pre-cooled feed air flow is largely freed of water and carbon dioxide.
Downstream of the cleaning system 3, the feed air flow is divided into subflows. The air of the feed air flow is cooled in the main heat exchanger 7 in a fundamentally known manner. In the example illustrated here, two so-called turbine flows are formed in the corresponding turbines. In this case, the booster unit of the turbine booster 6 is designed as what is known as a cold booster, i.e., it is fed with already cooled air from the main heat exchanger 7. Air which has been completely cooled in the main heat exchanger 7 is expanded in a liquefied state via throttle valves, which are not separately labeled, and fed into the rectification column system as what are known as throttle flows.
An oxygen-enriched liquid bottom fraction and a nitrogen-enriched gaseous top fraction are formed in the pressure column 11. The oxygen-enriched liquid bottoms fraction is drawn off from the pressure column 11 and expanded in proportions into the evaporation chambers of the reflux or bath condenser evaporators in the head gas condensation arrangements 13.10 and 14.10. Gas proportions formed by the expansion and evaporation against the head gas of the raw or pure argon column 13, 14 are fed into the low-pressure column 12, as is the case here with unevaporated liquid.
The operation of the air separation unit 90 illustrated here is of common knowledge in this technical field and reference is made to the technical literature cited. The raw argon column 13 is usually fed from the low-pressure column 11, while the pure argon column 14 is usually fed from the raw argon column 13.
In all cases, an oxygen-enriched liquid drawn off from the pressure column 11 is labeled with A. Using a first proportion thereof, a first liquid pressure flow B is formed, which is expanded while a first flash gas is obtained and a first low-pressure liquid remains in a valve not separately labeled.
In the embodiments 100 and 200 according to
In the embodiment 300 according to
In all cases, using a second proportion of the oxygen-enriched liquid from the pressure column 11, a second liquid pressure flow D is formed, which is expanded while a second flash gas is obtained and a second low-pressure liquid remains, wherein the second flash gas is labeled in each case with E.
The raw argon column 13 is thus operated here in each case using a first head gas condensation arrangement 13.10 in which head gas of the raw argon column 13 is subjected to condensation with partial evaporation of a first cooling fluid provided using the first low-pressure liquid or a part thereof.
The pure argon column 14 is operated using a second head gas condensation arrangement 14.10 in which head gas of the pure argon column 14 is subjected to condensation with partial evaporation of a second cooling fluid provided using the second low-pressure liquid or a part thereof.
A first evaporation gas formed during the partial vaporization of the first cooling fluid or a part thereof and a first excess liquid remaining after the partial evaporation of the first cooling fluid or a part thereof are fed into the low-pressure column 12 in both embodiments 100, 200 and 300 according to
Likewise, a second evaporation gas formed during the partial evaporation of the second cooling fluid or a part thereof and a second excess liquid remaining after the partial evaporation of the second cooling fluid or a part thereof are fed into the low-pressure column 12, as illustrated by H and I.
Differences between the embodiments 100 and 200 according to
The first evaporation gas F or the part thereof fed into the low-pressure column 12 is always partially or completely fed into the low-pressure column 12 in a first feed-in region, in particular at a common position with the first excess liquid G.
The second evaporation gas H or the part thereof fed into the low-pressure column 12, on the other hand, is partially or completely fed into the low-pressure column 12 in a second feed-in region. Likewise, the second excess liquid I or the part thereof fed into the low-pressure column 12 is partially or completely fed into the low-pressure column 12 in the second feed-in region. The first flash gas C or a part thereof is partially or completely, and separately from the first evaporation gas F, fed into the low-pressure column 12 in the second feed-in region.
A transfer flow from the raw argon column 13 to the pure argon column is additionally labeled with T in
For this purpose, the two liquid pressure flows B and H are expanded together downstream of the bottom evaporator 600 of the pure argon column 14 in valve 601 and fed together via line 602 into this evaporation chamber of the second head gas condensation arrangement 14.10, which acts as a common phase separator. The first flash gas C is drawn off via line 603, together with the second evaporation gas E produced in the condenser evaporator 14.10. The first cooling fluid K is drawn off from the evaporation chamber of the second head gas condensation arrangement 14.10 together with the second excess liquid I via line 604 and fed separately into the evaporation chamber of a first head gas condensation arrangement (13.10) for the purpose of partial evaporation. The first head gas condensation arrangement (13.10) is designed as a forced-flow evaporator on the evaporation side. The remaining fluids to and from the first head gas condensation arrangement (13.10) are conducted as shown in
Compared to
The data lines between the measuring and actuating elements are shown as dashed lines in
FIC1 controls the supply of second excess liquid I to the low-pressure column 12. FIC2 controls the supply of condensate from the first head gas condensation arrangement (13.10) as a function of the feed quantity for the raw argon column. PIC1 controls the pressure on the evaporation side of the second head gas condensation arrangement (14.10). LIC1 controls the quantity of first cooling fluid flowing into the first head gas condensation arrangement (13.10). LIC2 controls the total quantity of coolant via the bottom level measurement in the high-pressure column.
FIC2 controls the evaporator performance (by backing up the liquid into block 13.10 and covering part of the condensation surface).
The liquid proportion in flow 701 is optionally calculated and adjusted by FIC1.
Alternatively, particularly stable operation can be achieved by using an additional phase separator 804 to separate the two-phase flow 701 into the first evaporation gas F and the first excess liquid G. This variant is shown in
The control is also shown in
Alternatively, instead of PIC2, a TIC (Temperature Indication and Control) controller can be used to control the temperature of the first cooling fluid as it enters the first head gas condensation arrangement (13.10). LIC3 controls the quantity of first cooling fluid flowing into the first head gas condensation arrangement (13.10), but in this case as a function of the value of the fill level in the phase separator 804. The quantity of second excess liquid I flowing to the low-pressure column is adjusted by means of LIC4 as a function of the liquid level on the evaporation side of the pure argon condenser. There are also FIC3 and FIC4 controllers in the lines for the second excess liquid G and the raw argon, which is transferred to the pure argon column 14. The FIC3 controller is particularly important here. This means that the liquid proportion in the flow 701 can be controlled directly (and not determined by calculation) and dry evaporation in the condenser can be avoided.
The special measures of
| Number | Date | Country | Kind |
|---|---|---|---|
| 21020635.5 | Dec 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/025517 | 11/17/2022 | WO |
