description

Method for separating a component mixture and separating device

The present invention relates to a method for separating a

Component mixture that essentially contains hydrocarbons with two or two or more carbon atoms, methane and hydrogen, and one

Separating device according to the preambles of the independent claims.

State of the art

Methods and devices for steam cracking from

Hydrocarbons are known and for example in the article "Ethylene" in

Ullmann's Encyclopedia of Industrial Chemistry, online since April 15, 2007, DOI 10.1002 / 14356007.a10_045.pub2. By steam cracking, but also using other methods and devices, component mixtures are obtained in the form of so-called raw or cracked gases which, after treatment, remove water and carbon dioxide as well as oil or gasoline-like gases

Comprises components, are at least partially separated into the components contained in each case. This can be done in different ways.

The present invention can be used to remove methane and hydrogen from a component mixture which essentially contains hydrocarbons with two carbon atoms, methane and hydrogen, but is poor in or free from heavier hydrocarbons, and is described below in particular with reference to this variant . Such a component mixture is known from the literature cited

Separation sequences, especially in the case of a deethanization of the processed

Fission gas obtained if this deethanization is the first step in the separation process. As explained again below, such a component mixture or a corresponding material flow is usually also referred to as a "C2 minus flow".

However, the present invention can also be used to remove methane and

Hydrogen from a mixture of components that essentially

Hydrocarbons with two or more carbon atoms, methane and hydrogen, can be used. Such a component mixture can be present in particular in the form of the cracked gas prepared as explained but not yet further treated by separation technology.

In both cases, i.e. the removal of methane and hydrogen from one

Component mixture, which is essentially hydrocarbons with two

Contains carbon atoms, methane and hydrogen, but is poor in or free of heavier hydrocarbons, and in the removal of methane and

Hydrogen from a mixture of components that essentially

Contains hydrocarbons with two or more carbon atoms, methane and hydrogen, is so-called in the context of the present invention

Demethanization made. In the former case, this is the second and in the latter case it is the first of a corresponding separation sequence.

Conventional methods, for example a method as shown in FIG. 1

is illustrated, comprise stepwise cooling a C2minus stream under pressure in heat exchangers and respectively separating liquid condensates downstream of these heat exchangers. An abs at a pressure of about 30 bar. and a temperature of below about -10 ° C remaining in gaseous form, the proportion of the originally fed-in C2minus current is expanded in an expander. The one in that

The expander expanded portion and the condensates previously separated from the C2minus stream are fed into a rectification column at different levels

(so-called demethanizer) fed in.

In the bottom of the rectification column is a liquid bottom product that is in

Has essentially hydrocarbons with two hydrocarbons, formed and withdrawn. A gaseous overhead product that is essentially methane and

Contains hydrogen, is withdrawn from the top of the rectification column as an overhead stream and cooled to about -10 ° C by releasing the pressure in an expander.

The expanded overhead stream is used to cool and at least partially liquefy a first gaseous stream from the rectification column in a first plate exchanger and a second gaseous stream in a second

Plate heat exchanger used. The rectification column used is designed in two parts and the at least partially liquefied gaseous substance streams are used as reflux to the two parts of the rectification column.

The relaxed overhead stream is then used to cool the C2minus stream and thus used in the formation of the condensates.

A corresponding method is also disclosed in DE 10 2005 050 388 A1. FR 2 957 931 A1 and JP S61 189233 A also show processes for treating gas mixtures from vapor cracking processes.

The disadvantage of the method explained is that the plate exchangers mentioned, which are used for cooling and at least partially liquefying the first gaseous stream and the second gaseous stream from the rectification column, have to be arranged above the rectification column so that these streams or the liquefied fractions as Rewind to the

Rectification column can flow back. The relaxed overhead flow with a certain liquid component due to the relaxation has to be complex to this

Plate exchangers are transported up. The use of this relaxed overhead flow as a refrigerant in the plate exchangers at high altitudes is associated with technical difficulties, since the liquid and gas phases are preferably fed separately into the plate exchangers and a low pressure loss can be tolerated.

The installation of the plate exchanger at the top of the rectification column is complete

in summary, complex and costly. The same also applies to a comparable demethanization of a component mixture, which in addition to

Hydrocarbons with two carbon atoms are also heavier

Contains hydrocarbons. The object of the invention is therefore to eliminate these disadvantages of the prior art.

Disclosure of the invention

Against this background, the invention proposes a method for separating a component mixture which essentially contains hydrocarbons with two or two or more carbon atoms, methane and hydrogen, and a corresponding separating device with the respective features of the independent patent claims. Preferred configurations are the subject of the dependent claims and the following description.

Before explaining the features and advantages of the present invention, the fundamentals and the terms used are explained.

The present invention is particularly directed to the separation of

Mixtures of components are used that are obtained by steam cracking processes. However, it is not limited to these. That essentially

Component mixture containing hydrocarbons having two or two or more carbon atoms, methane and hydrogen, when it is produced using a steam cracking process, is formed as a fraction of a so-called cracked gas formed in the steam cracking process. For this purpose, a corresponding cracked gas is typically freed from water, acid gases and oil and gasoline-like components and compressed, as already explained. It then represents the component mixture containing essentially hydrocarbons with two and more carbon atoms, methane and hydrogen Rectification,

Either the essentially hydrocarbons with two or more

Carbon atoms, methane and hydrogen-containing component mixture or the component mixture containing essentially hydrocarbons with two carbon atoms, methane and hydrogen can be processed (“demethanized”) within the scope of the present invention.

Common methods include separating the cracked gas into a series of

Fractions based on the different boiling points of the contained

Components. In the professional world, short names are used for this, which indicate the number of carbon atoms in each predominantly or exclusively contained

Specify hydrocarbons. A "C1 fraction" is a fraction that predominantly or exclusively contains methane (however, according to convention, it may also contain hydrogen, then also called the "Cl minus fraction"). A "C2 fraction", however, contains predominantly or exclusively ethane, ethylene and / or acetylene. A "C3 fraction" contains predominantly propane, propylene, methylacetylene and / or propadiene. A “C4 fraction” contains predominantly or exclusively butane, butene, butadiene and / or butyne, it being possible for the respective isomers to be contained in different proportions depending on the source of the C4 fraction. The same applies to the "C5 fraction" and the higher fractions. Several such fractions can also be combined in terms of procedures and / or names.

As used herein, component mixtures can be rich or poor in one or more components, with "rich" for a content of at least 90%, 95%, 99%, 99.5%, 99.9%, 99.99% or 99.999 % and "poor" can mean a content of no more than 10%, 5%, 1%, 0.1%, 0.01% or 0.001% on a molar, weight or volume basis. In the language used here, component mixtures can also be enriched or depleted in one or more components, these terms relating to a content in another component mixture from which the component mixture under consideration was obtained. The component mixture is "enriched" if it is at least 1, 1-fold, 1, 5-fold, 2-fold, 5-fold, 10-fold, 100-fold or 1,000-fold content, "depleted"

0.01 times or 0.001 times the content of a component, based on the other component mixture. Does this mean that a

Component mixture “essentially” contains one or more components, this is understood in particular to mean that the component mixture is at least rich in the one or more components in the sense explained above or has exclusively the one or more components.

A component mixture is "derived" from another component mixture if it has at least some components contained in or obtained from the other component mixture. A derived in this sense

Component mixture can consist of another component mixture

Separating or branching off a subset or one or more components, enrichment or depletion with regard to one or more components, chemical or physical conversion of one or more components, heating, cooling, pressurizing and the like can be obtained.

The present application used to characterize pressures and

Temperatures the terms "pressure level" and "temperature level", which is intended to express that corresponding pressures and temperatures do not have to be used in the form of exact pressure or temperature values. However, such pressures and temperatures typically move in certain ranges, for example ± 1%, 5% or 10% around a mean value.

Corresponding pressure levels and temperature levels can lie in disjoint areas or in areas that overlap one another. In particular, pressure levels close slightly different pressures that are due to

result in unavoidable or expected pressure losses. The same applies to temperature levels. The pressure levels specified here in bar are absolute pressures.

A "heat exchanger" serves for the indirect transfer of heat between at least two material flows, for example, which are conducted in countercurrent to one another, for example a warmer gaseous material flow and one or more colder liquid material flows. A heat exchanger can be formed from a single or several parallel and / or serially connected heat exchanger sections, for example from one or more plate heat exchanger blocks. A heat exchanger has "passages" which are designed as separate fluid channels with heat exchange surfaces.

A "liquid separator" or "separating container" is a container in which a liquid, so-called condensate, is separated from a gaseous substance flow or a two-phase flow (which is partly liquid and partly gaseous). The condensate can be removed from the liquid separator (typically from an upper area, "head") at least partially in gaseous form.

In the parlance used here, a "rectification column" is a separation unit which is set up to at least partially provide a component mixture (fluid) provided in gaseous or liquid or in the form of a two-phase mixture with liquid and gaseous fractions, possibly also in the supercritical state to separate, ie to produce from the component mixture each pure substances or component mixtures which are enriched or depleted or rich or poor in the sense explained above with respect to the component mixture with regard to at least one component. Rectification columns are from the area of

Separation technology well known. Rectification columns are typically designed as cylindrical metal containers which are equipped with internals, for example sieve trays or ordered and disordered packings. A

Rectification column is characterized, among other things, by the fact that a liquid fraction separates out in its lower area, also known as the bottom. This liquid fraction, here referred to as sump liquid, is in a

Rectification column heated by means of a sump evaporator, so that part of the sump liquid continuously evaporates and rises in gaseous form in the rectification column. A rectification column is also typically provided with what is known as an overhead condenser, into which at least part of a gas mixture or a gas mixture which is enriched in an upper region of the rectification column

corresponding clean gas, here referred to as top gas, fed in partially liquefied to form a condensate and as a liquid return at the top of the

Rectification column is abandoned. Part of the condensate obtained from the top gas can be used for other purposes. For the design and configuration of rectification columns, reference is made to relevant textbooks (see, for example, Sattler, K: Thermal Separation Processes: Fundamentals, Design, Apparatus, 3rd Edition 2001, Weinheim; Wiley-VCH).

A "distillation device" is the one used here

Linguistic usage of a separation device which has at least two different distillation units. A distillation unit can, for example, be a rectification column or comprise components such as are typical for a rectification column. A distillation device can also be designed in the form of a rectification column, which has two sections that are separated from one another by a tray, with liquid accumulating on the tray, which flows off via a weir into the section below and thus a return to the section below Section forms. An exchange of liquids via lines can also take place.

Advantages of the invention

The present invention is based on a method known to that extent for separating a component mixture which essentially comprises hydrocarbons with two or two or more carbon atoms, as well as methane and hydrogen. As explained above, such a component mixture can be present as a processed but not yet further processed cracked gas, but also as a C2 minus fraction. Such a method is carried out using a

Performed distillation device, in which a methane and hydrogen-containing stream of a heavier portion is separated, so a component mixture that essentially hydrocarbons with two or two or more

Has carbon atoms, and a component mixture, which essentially comprises methane and hydrogen, are formed.

In such a method, the fluid of the component mixture is gradually cooled at a first pressure level from a first temperature level via two or more intermediate temperature levels to a second temperature level. At each of the intermediate temperature levels, condensates are deposited from the fluid at the first pressure level, that is to say without any relaxation.

It is stated here that "fluid of a material flow" or "fluid of a

Component mixture "is treated in any way, this is understood to mean that, for example, the entire fluid, a fluid derived from a starting fluid or a partial flow of a material flow that was formed from a corresponding fluid is used Condensate and a portion remaining in gaseous form are formed from a corresponding fluid.

Fluid of the component mixture that remains gaseous at the second temperature level, i.e. the fluid that is not deposited in the form of the respective condensates, is fed into an expander at the first pressure level and expanded to a second pressure level, with the expansion resulting in cooling and partial condensation takes place and thus a two-phase flow with a liquid part and a gaseous part is formed.

The one by cooling to the intermediate temperature levels and the second

The condensates formed at the temperature level and the two-phase stream are each at least partially fed into a distillation device that is operated at the second pressure level, with at least one liquid stream in the distillation device, which essentially comprises hydrocarbons with two or two or more carbon atoms, and a gaseous stream, the in

Essentially comprising methane and hydrogen, obtained and from the

Distillation device are withdrawn.

In the process, the fluid is transferred to the

Intermediate temperature levels and the second temperature level formed condensates and the two-phase flow from the first pressure level to a second pressure level below the first pressure level and expanded into the

Distillation device fed, which is operated at the second pressure level.

According to the invention, the mentioned second temperature level is -125 to -150 T, in particular about -145 TD. This is well below the corresponding

Temperature levels as used in processes according to the prior art when cooling corresponding feed mixtures. Reference is made to the example in FIG. Due to the subsequent relaxation, the temperature level is again significantly reduced, in the example from approx. -145 TD in particular to approx. -162 TD.

According to the invention, the distillation device comprises a first distillation unit and a second distillation unit, the first distillation unit being operated with a third temperature level at the top, which is below the second temperature level, and the second distillation unit being operated at a fourth temperature level at the top, which is above the second temperature level is operated. The liquid portion of the two-phase stream is at least partially given up as return to the first distillation unit. However, this does not rule out that the gaseous portion of the two-phase stream can also be fed at least partially into the first distillation unit. On the one hand, the liquid part of the two-phase flow is used as the return. Another effect which also results from feeding in the gaseous component, however, is that even more liquid is formed from the ascending gas flow of the first separation unit due to the cold temperature of the relaxed two-phase flow (e.g. approx. -162 TD). This happens because the temperature level of the

Two-phase flow after the expansion is even lower than the third temperature level at the top of the column (namely, for example, ca -152 TD). The mentioned

direct and indirect effects can contribute equally to the formation of reflux.

In particular, the liquid portion of the two-phase stream or a corresponding partial amount thereof is fed into an upper, head-near area of ​​the first distillation unit or at the top thereof, a "head-near" area being in particular an area without trays and / or packings, which is directly below a upper end of the first distillation unit is located. In the language used here, the "head" denotes the topmost area of ​​a

Distillation unit above which the corresponding distillation unit has no further dividing trays or packings.

Preferably, in the context of the present invention, the first

Distillation unit operated without a return line, which is formed from fluid that is withdrawn in gaseous form from the first distillation unit. In other words, the first distillation unit is advantageously operated without a top condenser. The second distillation unit, in particular geodetically below the first

Can be arranged distillation unit, however, is operated in particular with a top condenser, which is geodetically above the first

Distillation unit can be arranged. The assignment of a top condenser to a distillation unit results from the fluid or top gas treated there, but not from the arrangement.

The liquid stream, which essentially comprises hydrocarbons with two or two or more carbon atoms, becomes the second from the sump

Distillation unit and the gaseous stream, which essentially comprises methane and hydrogen, withdrawn at the top of the first distillation unit.

The third temperature level below the second temperature level at the top of the first distillation unit results in particular from the feeding in of the fluid cooled to the second temperature level and then relaxed, that is to say the two-phase flow. Advantageously, no gaseous fluid is removed from the first distillation unit that liquefies as a return to the first

Distillation unit is returned, but all liquid in the first

Fluid fed into the distillation unit is provided exclusively in the form of the condensates formed by cooling to the intermediate temperature level and the second temperature level and / or a liquid portion of the two-phase flow or parts thereof.

By operating the first distillation unit with the third temperature level at the top and feeding in particular the two-phase stream into the first

Distillation unit or the liquefied portion as a return flow to this, an overhead flow essentially free of hydrocarbons with two carbon atoms, namely the already mentioned gaseous substance flow, which essentially comprises methane and hydrogen, can be obtained without a return flow from overhead gas by means of separate and especially over the head of the

Rectification column arranged heat exchanger must be formed as in the prior art.

The fourth temperature level above the second temperature level at the top of the second distillation unit is achieved in particular by the temperatures of the condensates fed into the distillation device, which are obtained by cooling to the intermediate temperature level and the second temperature level. By operating at a correspondingly higher temperature level, which is also above a corresponding temperature level according to the prior art, a return line to the second distillation unit can be formed without the need for strong cooling as in the prior art. Rather, known refrigerants such as ethylene can be used for this purpose. On

Ethylene refrigeration circuit is already available in a corresponding system for cooling the feed mixture, as already explained.

In the context of the present invention, as in the prior art, a gaseous material flow to be returned is thus also removed from the distillation device, but only from the mentioned second distillation unit, fed into a condenser, cooled and liquefied in the condenser, and onto the

Distillation device or its second distillation unit as reflux

given up. However, the condenser is operated at a temperature level above the second temperature level. The distillation device therefore advantageously has a condenser which is operated at such a temperature level.

By using the measures according to the invention it is avoided that, as in the prior art, a first gaseous stream from the rectification column in a first plate exchanger and a second gaseous stream in a second heat exchanger have to be cooled to very low temperatures and liquefied in order to reach the To be able to provide a reflux rectification column. In contrast to the known method, the present invention thus makes it possible to save the two plate exchangers at the top of the rectification column, in which conventionally almost the entire Cl minus fraction is used as refrigerant and which has to be transported to the plate exchangers in a laborious manner.

According to the invention, the third temperature level mentioned is -150 to -170 T, in particular about -162 TD. This is well below the temperature level used in processes according to the state of the art for cooling corresponding feed mixtures. Reference is made to the example in FIG. The fourth temperature level mentioned is -50 to -130 TD. The same applies to the temperature level in the capacitor mentioned. The first pressure level is in particular 25 to 30 bar, the second pressure level 10 to 15 bar.

The use of the solution according to the invention practically does not change the material and heat balance of a corresponding system and does not have any further influence on the overall process. The invention enables a reduction in investment costs and a simplification in the installation of the system.

Advantageously, the fluid of the gaseous substance stream withdrawn from the distillation device, which essentially comprises methane and hydrogen, that is to say overhead gas of the distillation device or of the first distillation unit, is the

Distillation device, at least for cooling the fluid of the

Hydrocarbon mixture from the first temperature level through the

Intermediate temperature levels used on the second temperature level. This enables the corresponding fluids to be cooled efficiently. Here can

In particular, further relaxation is done to the required depths

Generate temperatures. The gaseous stream withdrawn from the distillation device is withdrawn from it, for example at -150 to -160 TD, in particular about -153 TD. A corresponding temperature level is also referred to here as a fifth temperature level.

One of the intermediate temperature levels is advantageously from -120 to -125 T and one of the intermediate temperature levels from -140 to -145 TD. The cold top gas at the fifth temperature level is advantageously used to remove a portion of the gas that remained gaseous during an upstream condensation

Component mixture from the intermediate temperature level at -120 to -125 TD to the intermediate temperature level at -140 to -145 TD a bzukühlen, the top gas being heated to a temperature level of -120 to -130 TD, for example about -126 TD. The top gas is then advantageously cooled in an expander to a temperature level of -150 to -160 TD, for example about -157 TD, and for cooling portions of the component mixture that have remained gaseous in upstream condensations to intermediate temperature levels of for example -120 to -125 TD, -95 to -100 TD, -74 to -79 TD, and -48 to -53 TD are used. In addition, ethylene refrigerant is used to cool down accordingly to the intermediate temperature levels.

Advantageously, the bottom liquid of the first separation unit is collected and passed to the second separation unit in order to serve as a return or as cooling in the second separation unit.

The method according to the invention is particularly suitable for separating a component mixture that is obtained from a cracked gas obtained by means of a steam cracking process.

A corresponding separation device is also the subject of the invention. The separation device is set up to separate a component mixture containing essentially hydrocarbons with two or two or more carbon atoms and methane and hydrogen and has a distillation device, a condenser and at least one expander. For the other components of a corresponding system, reference is made to the explanations above.

The invention and embodiments of the invention are explained in more detail with reference to the accompanying drawings.

Brief description of the drawings

FIG. 1 shows a separation device for separating a component mixture according to the prior art.

FIG. 2 shows a separating device for separating a component mixture according to an embodiment of the invention.

FIG. 3 shows a separating device for separating a component mixture according to a second embodiment of the invention.

FIG. 4 shows a separating device for separating a component mixture according to a third embodiment of the invention.

Detailed description of the drawings

In the figures, elements that correspond to one another are indicated with identical reference symbols and are not explained repeatedly for the sake of clarity. In the following figures, the invention is described with reference to a separation treatment of a component mixture containing essentially hydrocarbons with two carbon atoms and methane and hydrogen. As mentioned, however, it is suitable in the same way for the separation treatment of a component mixture containing essentially hydrocarbons with two or more carbon atoms and methane and hydrogen.

FIG. 1 shows a separating device for separating a component mixture according to an embodiment not according to the invention. The separating device is designated as a whole by 200 and is used for separating a component mixture that is present in the

Essentially hydrocarbons with two carbon atoms, methane and

Has hydrogen (i.e. a C2minus fraction) set up. The C2minus fraction is fed to the separating device 200 in the form of a material flow a.

The separating device 200 comprises a first heat exchanger 1, a second heat exchanger 2 and a third heat exchanger 3. The material flow a is first passed through the first heat exchanger 1 and cooled therein. It is then fed into a first liquid separator 31. The cooling in the first heat exchanger 1 takes place in such a way that a liquid condensate separates in the first liquid separator 31. This is drawn off at the bottom of the first liquid separator 31 as stream b. The other

Use of the stream b is explained below.

A portion of the remaining gaseous in the first liquid separator 31

Material flow a is passed as material flow c through the second heat exchanger 2 and then fed into a second liquid separator 32. In this too, a liquid condensate is deposited on the bottom and is drawn off in the form of the stream d. A portion of the material flow c that still remains in gaseous form is passed as material flow e through a third heat exchanger 3 and then fed into a third liquid separator 33. In this too, a liquid condensate separates on the bottom and is drawn off in the form of the material flow f. A portion of the material flow e that still remains in gaseous form is passed as material flow k into an expander 20, expanded, and at least partially liquefied. A two-phase flow formed in this way becomes in the form of a material flow I.

provided.

The separating device 200 further comprises a rectification column 50 which is operated with a bottom evaporator 14 (not explained in more detail), the heat exchanger of which is operated, for example, with a propylene stream coming from other parts of the plant. The rectification column 50 is also assigned two plate exchangers 15, 16, the operation of which is explained below. The rectification column 50 has two sections 51, 52.

Due to the successive cooling of the streams a, c, e and k, the correspondingly obtained condensates, which are obtained in the form of the streams b, d, f, I, have different contents of hydrocarbons with two carbon atoms, methane and hydrogen. In particular, the stream I has a higher methane and hydrogen content than the stream f, the stream f has a higher methane and hydrogen content than the stream d, and the stream d has a higher methane and hydrogen content than the stream b.

The material flows b, d, f and I are therefore at different heights in the

Rectification column 50 fed in, which has suitable feed devices between the trays shown here in a highly schematic manner.

A gaseous stream n is withdrawn from the top of the rectification column 50 and expanded in an expander 21 and thereby greatly cooled or at least partially liquefied. The material flow n mainly contains methane and hydrogen (it is a so-called C1 minus fraction). The liquefied material flow n is passed through the two plate exchangers 15, 16 and used there for cooling. The material flow n is then passed through the heat exchanger 2 and used to cool the gaseous material flow c and passed through the heat exchanger 1 and used to cool the gaseous material flow a. The material flow n, in particular after use in a pre-cooling unit 99, is then passed through two boosters 22, 23 coupled to the expanders 20 and 21 and discharged from the system as tail gas.

In the bottom of the rectification column 50, a liquid condensate is deposited which consists essentially of hydrocarbons with two carbon atoms (it is therefore a so-called C2 fraction). The condensate is drawn off in the form of the material flow o, heated in the first heat exchanger 1 and then, for example, fed to a further separating device such as a C2 splitter.

Ein gasförmiger Stoffstrom m1 wird gasförmig aus der Rektifikationskolonne 50 an einer ersten Position entnommen, im Plattentauscher 16 abgekühlt und dadurch zumindest teilweise verflüssigt und der Rektifikationskolonne 50 als Rücklauf an einer zweiten Position zugeführt, also per Schwerkraft zurück in die Rektifikationskolonne 50 geleitet. Ein weiterer gasförmiger Stoffstrom m2 wird aus der Rektifikationskolonne 50 an einer dritten Position gasförmig entnommen, im Plattentauscher 15 abgekühlt und dadurch zumindest teilweise verflüssigt und der Rektifikationskolonne 50 als Rücklauf an einer vierten Position zugeführt, also per Schwerkraft zurück in die

Rectification column 50 passed, wherein the first position is below the second position, the second position is below the third position and the third position is below the fourth position. As mentioned above, the

Plate exchangers 15, 16 of the liquefied material flow n used to cool the material flows m1 and m2, which is expensive to the plate exchangers, which are in large

Must be transported. The installation of these plate exchangers 15, 16 at the top of the rectification column 50 is complex and expensive.

FIG. 2 shows a separating device 100 according to an embodiment of the invention. The separating device 100 comprises the essential components of the separating device 200 shown in FIG. 1. These are not explained again.

A rectification column with two sections is also provided in the separating device 100. This is referred to below as the distillation device 10. Its two sections are referred to below as the first distillation unit 11 and the second distillation unit 12. A capacitor 13 is assigned to the separating device. In the separating device 100, the first distillation unit 11 is arranged above the second distillation unit 12. The condenser 13 is also arranged above the first distillation unit 11. In contrast to the separating device 200 shown in FIG. 1, however, the plate exchangers 15, 16 were omitted here. A material flow m corresponding to the material flow m1 in the separating device 100 is cooled in the condenser 13 by means of an ethylene refrigerant and is at least partially liquefied in the process. The gaseous stream m is taken from the upper part of the second distillation unit 12 and fed into the lower part of the first distillation unit 11. Since the first distillation unit 11 and the second distillation unit 12 are separated from one another by means of a liquid dust base, the returned material flow m serves to provide a return to the second distillation unit 12. A material flow corresponding to the material flow m2 in the separating device 100 is not present here. Instead, a return to the first distillation unit 11 is provided as explained below. Since the first distillation unit 11 and the second distillation unit 12 are separated from one another by means of a liquid dust base, the returned material flow m serves to provide a return to the second distillation unit 12. A material flow corresponding to the material flow m2 in the separating device 100 is not present here. Instead, a return to the first distillation unit 11 is provided as explained below. Since the first distillation unit 11 and the second distillation unit 12 are separated from one another by means of a liquid dust base, the returned material flow m serves to provide a return to the second distillation unit 12. A material flow corresponding to the material flow m2 in the separating device 100 is not present here. Instead, a return to the first distillation unit 11 is provided as explained below.

The successive cooling of the C2minus flow a is expanded to include a heat exchanger 4 for cooling a gaseous substance flow g and a heat exchanger 5 for cooling a gaseous substance flow i. In addition to the condensates or material flows b, d, f and I, condensates or material flows h and j are separated in further liquid separators 34, 35. The portions remaining in gaseous form are passed through the heat exchangers 4 and 5 in the form of streams g and i and cooled to the intermediate temperature levels of -120 to -125 T (stream g) and -140 to -145 T (stream i). Since the material flow j has a higher proportion of methane and hydrogen than the material flow h, and the material flow h a higher methane

and have hydrogen content as the stream f, these are fed into the distillation device 10 at different levels.

The material flow I in the separating device 200 is formed in a manner comparable to that of the material flow I in the separating device 100, but is at a significantly lower temperature due to the further cooling in the heat exchangers 4 and 5.

Because of the further cooling, the streams j and I in particular can be used as return to the first distillation unit 11. A liquefaction of a material flow m2 as in the separation device 100 is therefore not necessary, so that, as mentioned, the heat exchangers 15, 16 can be dispensed with.

Since in the present invention the gaseous stream n, which is taken from the top of the distillation device, does not have to be used for cooling in the plate exchangers 15, 16, it can be used for cooling in the heat exchangers 1, 2, 3, 4, 5. In this way, the low temperatures mentioned can be achieved.

FIG. 3 shows a separating device 300 according to a further embodiment of the invention. In this case, the separating device according to the prior art was only expanded to include a heat exchanger 4 and a liquid separator 34.

In FIGS. 1 to 3, the heat exchangers 1 to 3 are each cooled using further material flows u, v, w and x. The material flows u, v and w are ethylene refrigerants at different pressure levels

Material flow x, for example, a recycled ethane flow. On

Ethylene refrigerant flow w through condenser 13 is indicated accordingly.

FIG. 4 shows the distillation unit 40 according to a further embodiment of the invention. Here, the condenser 13 is arranged between the first distillation unit 11 and the second distillation unit 12, the first distillation unit 11 above the condenser and the condenser 13 above the second

Distillation unit 12 is arranged. A material exchange takes place in the form of a

Material flow p and a material flow q.

Furthermore, the condenser 13 could be integrated directly into the distillation unit 40, for example in the form of a tube bundle or a block between the first distillation unit 11 and the second distillation unit 12.

The following table shows the temperatures of selected material flows. The information in brackets represents preferred temperature ranges, the value given after the brackets is a preferred example.

Claims

1. Process for the separation of a component mixture (C2minus) containing essentially hydrocarbons having two or two or more carbon atoms, methane and hydrogen using a

Distillation device (10) in which

- Fluid (a, c, e, g, i) of the component mixture (C2minus) at a first pressure level in stages from a first temperature level via two or more intermediate temperature levels to a second

Temperature level is cooled, with each of the

Intermediate temperature levels condensates (b, d, f, h, j) are separated from the fluid (a, c, e, g, i),

- Fluid (k) of the component mixture (C2minus), which is on the second

Temperature level remains gaseous by releasing the pressure from the first pressure level to a second pressure level below the first

Pressure level is cooled, whereby a two-phase flow (I) with a liquid and a gaseous portion is formed,

- Fluid of the condensates (b, d, f, h, j) and fluid of the two-phase stream (I) is fed into the distillation device (10) on the second

Pressure level is operated, wherein in the distillation device (10) at least one liquid stream (o), which essentially

Has hydrocarbons with two or two or more carbon atoms, and a gaseous stream (s), which essentially comprises methane and hydrogen, are obtained and withdrawn from the distillation device (10),

characterized in that

the second temperature level is -125 to -150 T,

the distillation device (10) has a first distillation unit (1 1) and a second distillation unit (12), the first

Distillation unit (11) is operated with a third temperature level at the top, which is below the second temperature level, and the second distillation unit (12) is operated at a fourth temperature level at the top, which is above the second temperature level, and

- The liquid portion of the two-phase stream is at least partially given up as return to the first distillation unit (11).

2. The method of claim 1, wherein the distillation device (10) a

Has condenser (13) which is operated at the temperature level above the second temperature level.

3. The method of claim 2, wherein the fluid of the condensates (b, d, f, h, j)

is fed at least partially into the first and into the second distillation unit (11) of the distillation device (10).

4. The method according to any one of claims 2 or 3, wherein a gaseous

Material flow (m) from the second distillation unit (12) of the

Distillation device (10) withdrawn, cooled in the condenser (13) and to provide a liquid return to the second

Distillation unit (12) is used.

5. The method according to any one of the preceding claims, wherein the liquid

Material flow (o) is relaxed from the second pressure level to a pressure level below the second pressure level.

6. The method according to any one of the preceding claims, wherein the fluid (a, c, e, g, i) of the component mixture (C2minus) using an ethane and / or ethylene refrigerant at different pressure levels from the first temperature level via the intermediate levels to the second Temperature level is cooled.

7. The method according to any one of the preceding claims, wherein the

Intermediate temperature levels an intermediate temperature level at -48 to -53 T and / or an intermediate temperature level at -74 to -79 T and / or a

Intermediate temperature level at -95 to -100 TD and / or an intermediate temperature level at -120 to -125 T and / or a

Intermediate temperature level at -140 to -145 TD included.

8. The method according to any one of claims 2 to 4, wherein the gaseous material flow (m) is cooled by an ethylene refrigerant in the condenser (13).

9. The method according to any one of claims 2 to 4 or 8, wherein the condenser (13) between the first distillation unit (1 1) and the second

Distillation unit (12) is arranged.

10. The method according to any one of the preceding claims, wherein the fluid des

gaseous stream (n) which is withdrawn from the distillation device (10), at least for cooling the fluid (a, c, e, g, i) of the

Carbon mixture (C2minus) is used from the first temperature level via the intermediate temperature level to the second temperature level.

1 1. The method according to any one of the preceding claims, wherein the fluid des

gaseous substance flow (s) which is withdrawn from the distillation device (10) is expanded in a further expander (21) to a third pressure level below the second pressure level.

12. The method according to claim 1 1, wherein the fluid of the gaseous

Material flow (n) that is withdrawn from the distillation device (10) is compressed after use for cooling the fluid (a, c, e, g, i) of the carbon mixture (C2minus), with the expander (20, 21 ) coupled compressors can be used.

13. The method according to any one of the preceding claims, which is used for separating a component mixture (C2minus) which is obtained from a cracked gas obtained by means of a steam cracking process.

14. Separation device (100), which is used to separate a substantially

Hydrocarbons with two or two or more carbon atoms, methane

and hydrogen-containing component mixture, wherein the separating device (100) has the following:

- Several indirect heat exchangers (1, 2, 3, 4, 5) which are set up to transfer fluid (a, c, e, g, i,) of the component mixture (C2minus) at a first pressure level gradually from a first temperature level through two or several intermediate temperature levels to a second

Cool down temperature level and several liquid separators (31, 32, 33, 34, 35), which are set up on each of the

Separate intermediate temperature levels of condensates (b, d, f, h, j) from the fluid (a, c, e, g, i),

- One or more expanders (20), which is or are set up for this, fluid (k) of the component mixture (C2minus) that remains gaseous at the second temperature level by releasing it from the first pressure level to a second pressure level below the first

To cool pressure levels, and thereby to form a two-phase flow (I) with a liquid and a gaseous component,

- A distillation device (10) and feed lines for it

are set up, fluid of the condensates (b, d, f, h, j) and fluid of the

Feed the two-phase stream (I) into the distillation device (10), the distillation device (10) for operation at the second pressure level and for the formation of a liquid stream (o), which in the

Substantially hydrocarbons with two carbon atoms, and a gaseous stream (s), which essentially comprises methane and hydrogen, is set up, wherein a withdrawal line is provided which is set up to withdraw the liquid stream (s) from the distillation device (10) ,

characterized in that

the distillation unit (10) is divided into a first distillation unit (1 1) and a second distillation unit (12), the first

Distillation unit (11) is set up to be operated at the top with a third temperature level below the second temperature level, and the second distillation unit (12) is set up at a fourth temperature level above the second at the top

Temperature levels to be operated, and

- A return line is provided which is set up for the

to give up liquid portion of the two-phase stream at least partially as return to the first distillation unit (10).

15. Separating device (100) according to claim 14, which is for performing a

Method according to one of claims 1 to 13 is set up.