EA041607B1 - METHOD FOR SEPARATING A MIXTURE OF COMPONENTS - Google Patents

Description

The invention relates to a method for separating a mixture of components containing essentially hydrocarbons having two or two or more carbon atoms, methane and hydrogen, and to a separation device described in independent claims.

State of the art

Methods and devices for steam cracking of hydrocarbons are known and are described, for example, in the article Ethylene in Ullmann's Encyclopedia of Industrial Chemistry posted online April 15, 2007, DOI 10.1002/14356007.al0_045.pub2. By steam cracking, as well as using other methods and devices, mixtures of components are obtained in the form of so-called crude gases or cracked gases, which, after processing, including the removal of water and carbon dioxide and oil or gasoline-like components, are separated, at least partially, to the components present in each case. This can be done in various ways.

The present invention can be used to remove methane and hydrogen from a mixture of components containing essentially hydrocarbons having two carbon atoms, methane and hydrogen, and also having a reduced content of heavier hydrocarbons or free of heavier hydrocarbons, and it is described in this application. in particular with reference to this option. A mixture of components of this type is obtained by means of a separation sequence known in the cited literature, in particular in the process of deethanization of the processed cracked gas, when such deethanization occurs first in the separation process. As emphasized again below, a mixture of this type of component, or the corresponding stream of matter, is commonly referred to as C2 minus stream.

However, the present invention can still be used to remove methane and hydrogen from a mixture of components containing essentially hydrocarbons having two or more carbon atoms, methane and hydrogen. A mixture of components of this type may be substantially in the form of a cracked gas which has been treated as indicated, but must still be further processed by separation methods.

In both cases, i.e. both the removal of methane and hydrogen from a mixture of components containing essentially hydrocarbons having two carbon atoms, methane and hydrogen, but a lower content of heavier hydrocarbons, or free of heavy hydrocarbons, and the removal of methane and hydrogen from a mixture of components containing essentially hydrocarbons having two or more carbon atoms, methane and hydrogen, that is, in the present invention, carry out what is called demethanization. This operation occurs second in the respective splitting sequence in the first case and first in the last case.

Conventional methods, such as the method illustrated in FIG. 1 involves stepwise cooling of the C2 minus pressurized flow in heat exchangers and separation of liquid condensates in each case downstream of these heat exchangers. The fraction C2 minus the flow initially fed into it, which remains in a gaseous state at a pressure of about 3 MPa (30 bar) (abs.) and a temperature below about -100° C., is expanded in an expander. The fraction expanded in the expander and the condensates separated from the C2 minus stream earlier are fed to a distillation column (called a demethanizer) at different levels.

At the bottom of the distillation column, a liquid bottom product containing essentially hydrocarbons having two carbon atoms is formed and recovered. The overhead product gas, containing essentially methane and hydrogen, is removed at the top of the distillation column as an overhead stream and cooled to about -160° C. by expansion in an expander.

The expanded overhead stream is used to cool and at least partially liquefy the first gaseous material stream from the distillation column in the first plate heat exchanger and the second gaseous material stream in the second plate heat exchanger. The distillation column used consists of two parts and the gaseous substance streams which have been at least partially liquefied in each case are used as a return flow to the two parts of the distillation column. The expanded overhead stream is then used to cool the C2 minus stream and hence is used in the formation of condensates.

A corresponding method is also described in DE 102005050388 A1. In addition, FR 957931 A1 and JP S61189233 A show methods for treating gas mixtures from steam cracking processes.

The disadvantage of this method is that said plate heat exchangers, which are used to cool and partially liquefy the first gaseous substance stream and the second gaseous substance stream from the distillation column, must be located upstream of the distillation column so that these substance streams or liquefied fractions can flow back into distillation column in the form of reverse flow. The expanded top stream, with some liquid fraction due to expansion, must be transferred back to these plate heat exchangers in a complicated way. The use of expanded overhead as a coolant in high altitude plate heat exchangers is technically difficult because the liquid phase and gas phase are preferably sent separately to the plate heat exchangers and a lower pressure drop can be maintained.

As a result, the installation of plate heat exchangers at the top of the distillation column is inconvenient and costly. The same is true when comparing the demethanization of a mixture of components containing not only hydrocarbons having two carbon atoms, but also heavier hydrocarbons. Thus, the problem to which the present invention is directed is to solve these shortcomings of the prior art.

Description of the invention

In contrast to the prior art, the present invention proposes a method for separating a mixture of components containing essentially hydrocarbons having two or two or more carbon atoms, methane and hydrogen, and a corresponding separation device, which have the corresponding features specified in the independent claims . Preferred configurations are the subject of the dependent claims and the following description.

Before disclosing the features and advantages of the present invention, the basics will be disclosed and definitions of the terms used will be given.

The present invention is particularly useful for separating mixtures of components that are produced by steam cracking processes. However, it is not limited to this. A mixture of components containing essentially hydrocarbons having two or two or more carbon atoms, methane and hydrogen, if produced by the steam cracking process, is formed as a fraction of the cracked gas produced by the steam cracking process. To this end, the corresponding cracking gas is usually freed from water, acid gases and oil- and gasoline-like components, and compressed, as already indicated. After that, it is a mixture of components containing essentially hydrocarbons having two or more carbon atoms, methane and hydrogen. A mixture of components containing essentially hydrocarbons having two carbon atoms, methane and hydrogen, can, in turn, be formed from it by removing hydrocarbons having three or possibly more carbon atoms, especially by rectification. According to the present invention, either a mixture of components containing essentially hydrocarbons having two or more carbon atoms, methane and hydrogen, or a mixture of components containing essentially hydrocarbons having two carbon atoms, methane and hydrogen can be processed (demethanized).

Standard methods involve separating the cracked gas into a number of fractions based on the different boiling points of the components present. These fractions are referred to in the art by abbreviations indicating the number of carbon atoms in the hydrocarbons predominantly or exclusively present in each case. Thus, the C1 fraction is a fraction containing predominantly or exclusively methane (but by conversion in some cases also hydrogen, therefore also called the C1 minus fraction). In contrast, the C2 fraction contains predominantly or exclusively ethane, ethylene and/or acetylene. The C3 fraction predominantly contains propane, propylene, methylacetylene and/or propadiene. The C4 fraction contains predominantly or exclusively butane, butene, butadiene and/or butyne, the respective isomers being present in different proportions depending on the source of the C4 fraction. The same applies, respectively, to the C5 fraction and the higher molecular weight fractions. Several fractions of this type may also be combined in terms of method and/or purpose. For example, the C2 plus fraction contains predominantly or exclusively hydrocarbons having two or more carbon atoms, and the C2 minus fraction contains predominantly or exclusively hydrocarbons having one or two carbon atoms.

In the terminology used in this application, mixtures of components may be saturated or poor in one or more components, and saturated may correspond to a content of at least 90, 95, 99, 99.5, 99.9, 99.99 or 99.999%, and lean may correspond to a content of not more than 10, 5, 1, 0.1, 0.01% or 0.001% in moles, by mass or by volume. In the terminology used in this application, mixtures of components can also be enriched or depleted in one or more components, and these terms refer to the content in another mixture of components from which the mixture of components of interest was obtained. A mixture of components is enriched when it contains at least 1.1-fold, 1.5-fold, 2-fold, 5-fold, 10-fold, 100-fold or 1000-fold content, and depleted when it contains no more than 0, 9-fold, 0.5-fold, 0.1-fold, 0.01-fold or 0.001-fold content of the component, based on another mixture of components. If this application says that a mixture of components contains essentially one or more components, this, in particular, should be understood so that the mixture of components is at least saturated with one or more components in the above sense or exclusively contains one or more components .

A mixture of components is derived from another mixture of components when it contains at least some of the components present in or derived from the other mixture of components. The mixture of components thus obtained can be obtained from another mixture of components by separating or diverting a portion or one or more components, enriching or depleting one or more components, chemically or physically converting one or more components, heating, cooling, compressing and the like.

The terms pressure level and temperature level are used in this application to characterize pressures and temperatures and are intended to express the fact that the corresponding pressures and temperatures need not be used as precise pressure/temperature values. However, such pressures and temperatures usually vary within certain ranges, such as ± 1% or 10% of the mean value. The respective pressure levels and temperature levels may be in non-overlapping ranges or in overlapping ranges. More specifically, pressure levels include small pressure differences that occur due to unavoidable or expected pressure drops. The same goes for temperature levels. The pressure levels given in this application in bar are absolute pressures.

The heat exchanger serves to indirectly transfer heat between at least two substance streams, carried out, for example, in countercurrent to each other, for example, a warmer gaseous substance stream and one or more cold liquid substance streams. The heat exchanger may be formed from a single heat exchanger section or a plurality of heat exchanger sections connected in parallel and/or in series, such as one or more plate heat exchanger units. The heat exchanger has passages formed as separate fluid channels with heat exchange surfaces.

A liquid separator or separation tank is a vessel in which a liquid, called condensate, is separated from a gaseous stream of matter or separated from a two-phase stream (which is partly liquid and partly gaseous). The condensate can be removed at least partially in the gaseous state from the liquid separator (usually from the upper region, from above).

In the terminology used in this application, a distillation column is a separation unit designed to at least partially fractionate a mixture of components (fluid) provided in gaseous or liquid form or in the form of a two-phase mixture having liquid and gaseous components, possibly even in a supercritical state, i.e. to obtain pure substances or a mixture of components in each case from a mixture of components that are enriched/depleted or saturated/poor in relation to at least one component compared to the mixture of components in the above sense. Distillation columns are fairly well known in the field of separation technology. Distillation columns are typically in the form of cylindrical metal vessels fitted with internals such as distillation trays or ordered or random packings. One of the features of the distillation column is that the liquid fraction is separated in its lower region, also called the cube. This liquid fraction, referred to in this application as the bottom liquid, is heated in the distillation column by means of a reboiler, so that part of the bottom liquid is continuously evaporated and rises in a gaseous state in the distillation column. The distillation column is also usually equipped with a so-called top condenser, which is fed with at least a part of the gas mixture that accumulates in the upper region of the distillation column, or the corresponding pure gas, referred to in this application as the top gas, is partially liquefied to form a condensate and used as a return liquid flow at the top of the distillation column. Some of the condensate obtained from the top gas can be used in several other ways. With regard to the design and specific configuration of distillation columns, reference is made to the relevant textbooks (see, for example, Sattler, K: Thermische Trennverfahren: Grundlagen, Auslegung, Apparate [Thermal Separation Processes: Basics, Design, Apparatuses], 3rd edition 2001, Weinheim; Wiley-VCH).

In the terminology used in this application, the distillation device is a separation device having at least two different distillation units. The distillation apparatus may, for example, be a distillation column or contain components common to a distillation column. The distillation apparatus may also take the form of a distillation column having two sections separated from one another by a tray, where the liquid accumulates on the tray and flows down a trough to the bottom section and therefore forms a backflow to the bottom section. Fluid exchange is also possible along the circuits.

Advantages of the present invention

The present invention results from a process known in this regard for separating a mixture of components containing essentially hydrocarbons having two or two or more carbon atoms and methane and hydrogen. As mentioned above, a mixture of components of this type may take the form of a cracked gas that has been processed but not yet subjected to separation processes, or a C2 minus fraction. This type of process is carried out using a distillation device in which a stream of material containing methane and hydrogen is separated from a heavier fraction, i.e. a mixture of components is formed containing essentially hydrocarbons having two or two or more carbon atoms, and a mixture of components containing essentially methane and hydrogen.

In such a method, the fluid from the mixture of components at the first pressure level is gradually cooled from the first temperature level through two or more intermediate temperature levels to the second temperature level. At each of the intermediate temperature levels from the fluid from

- 3 041607 separate condensates at the first pressure level, i.e. in each case without expansion.

If this application indicates that a fluid from a stream of matter or a fluid from a mixture of components is processed in some way, this means, for example, that the entire fluid is used, the fluid obtained from the original fluid, or a substream of the substance stream, which formed from the appropriate fluid. More specifically, in the above process step, the condensate and the fraction which remains in the gaseous state are generated in each case from the corresponding fluid. The fraction that remains in the gaseous state is cooled in each case to the next lowest temperature level (ie the intermediate temperature levels or eventually the second temperature level).

The fluid from the mixture of components which remains in the gaseous state at the second temperature level, i.e. the fluid which does not separate in the form of the respective condensates, is fed into the expander at the first pressure level and expanded to the second pressure level, the expansion results in cooling and partial condensation and, consequently, the formation of a two-phase flow containing a liquid and a gaseous part.

Each of the condensates formed by cooling to intermediate temperature levels and a second temperature level and the two-phase stream is fed at least in part to a distillation apparatus that is operated at a second pressure level, where at least one liquid stream of matter containing essentially , hydrocarbons having two or two or more carbon atoms, and a gaseous stream of matter containing essentially methane and hydrogen are produced in the distillation device and removed from the distillation device.

In this method, the fluid from each of the condensates formed upon cooling to intermediate temperature levels and a second temperature level and from a two-phase stream is expanded from a first pressure level to a second pressure level that is lower than the first pressure level, and is fed to a distillation device that is operated at the second pressure level.

According to the present invention, said second temperature level is from -125 to -150°C, in particular about -145°C. This is well below the respective temperature levels used in the prior art processes when cooling the respective feed mixtures. Reference is made to the example in FIG. 1. Due to successive compression, the temperature level is significantly reduced again, in this example from about -145°C to, in particular, about -162°C.

According to the present invention, the distillation apparatus comprises a first distillation unit and a second distillation unit, wherein the first distillation unit is operated at a third temperature level at its top, which is lower than the second temperature level, and the second distillation unit is operated at a fourth temperature level, at its top, which is higher than second temperature level. The liquid portion of the two-phase stream is at least partially fed to the first distillation unit. However, this does not exclude the possibility that the gaseous part of the two-phase stream can also be fed, at least in part, to the first distillation unit. On the other hand, the liquid part of the two-phase flow is used as reflux. An additional effect, however, is that the low temperature of the expanded two-phase stream (eg, approximately -162° C.) produces even more liquid from the rising gas stream from the first separation unit. This is because the temperature level of the two-phase flow after expansion is even lower than the third temperature level at the top of the column (eg, approximately -152°C). These direct and indirect effects can contribute equally to the formation of phlegm.

In particular, the liquid part of the two-phase stream or its corresponding partial amount is fed into the upper region close to the upper part of the first distillation unit, or near its upper part, while the region close to the upper part is, in particular, the area without plates and/ or nozzle, which is located directly below the top tap of the first distillation unit. The term head refers to the uppermost part of the distillation unit, above which the corresponding distillation unit has no additional separating plates or nozzles.

Preferably, in the context of the present invention, the first distillation unit is operated without reflux, which is formed by the fluid vented in the gaseous state from the first distillation unit. In other words, the first distillation unit is advantageously operated without an overhead condenser. The second distillation unit, which may in particular be located vertically below the first distillation unit, is operated in particular with an overhead condenser which may also be located vertically above the first distillation unit. The purpose of the head condenser in the distillation unit arises as a result of the fluid or head gas treated there, but not the location.

A liquid material stream comprising essentially hydrocarbons having two or two or more carbon atoms is removed from the bottom of the second distillation unit, and a gaseous material stream comprising essentially methane and hydrogen from the top of the first distillation unit.

The third temperature level, which is lower than the second temperature level, in the upper part of the first distillation unit is, in particular, a consequence of the supply of a fluid that has been cooled to the second temperature level and then expanded, i.e. a two-phase flow. Mainly gaseous

- 4 041607 the fluid that is recycled to the first distillation unit as a liquefied reflux is not withdrawn from the first distillation unit; instead, all fluid supplied to the first distillation unit in a liquid state is provided solely as condensates formed by cooling to intermediate temperature levels and a second temperature level and/or as a liquid fraction of a two-phase stream, or a portion of each.

Operating the first distillation unit at a third temperature level at the top and feeding in particular a two-phase stream to the first distillation unit or liquid reflux means that it is possible to obtain an overhead stream that is substantially free of hydrocarbons having two carbon atoms, namely, a gaseous stream of the already mentioned substance, which contains essentially methane and hydrogen, without the need for refluxing from the upper gases by means of separate heat exchangers, which, in particular, are located above the top of the distillation column, as is done for this purpose in the prior art.

The fourth temperature level, which is higher than the second temperature level, in the upper region of the second distillation unit is achieved in particular by means of the temperatures of the condensates supplied to the distillation apparatus, which are obtained by cooling to intermediate temperature levels and the second temperature level. Operation at a correspondingly higher temperature level, which is also higher than the corresponding temperature level according to the prior art, allows the formation of a reflux in the second distillation unit without the need for significant cooling, as is done in the prior art for this purpose. Instead, known coolants such as ethylene can be used for this purpose. An ethylene cooling circuit is in any case present in the respective installation for cooling the feed mixture, as already indicated.

In the present invention, the recycled gaseous stream of matter is withdrawn, as in the prior art, from the distillation apparatus, but only from said second distillation unit, fed into the condenser, cooled in the condenser and liquefied, and used in the distillation apparatus or its second distillation unit as a reverse flow. At the same time, the capacitor is operated at a temperature level that is higher than the second temperature level. Thus, the distillation apparatus advantageously has a condenser which is operated at this temperature level.

The use of the measures according to the invention avoids, as in the prior art, the need to cool the first gaseous substance stream from the distillation column in the first plate heat exchanger and the second gaseous substance stream in the second heat exchanger to very low temperatures and liquefy them in order to be able to provide a return flow to the distillation column . In contrast to the known method, the present invention thus makes it possible to dispense with two plate heat exchangers in the upper region of the distillation column, which typically use almost all of the Ominus fraction as a coolant, and which must be transferred to the plate heat exchangers in a complex manner.

According to the present invention, said third temperature level is from -150 to -170°C, in particular about -162°C. This is well below the temperature levels used in prior art processes when cooling the respective feed mixtures. Reference is made to the example in FIG. 1. The specified fourth temperature level is -50 to -130°C. The same is true for the temperature level in said condenser. The first pressure level is in particular 25 to 30 bar, the second pressure level is 10 to 15 bar.

The application of the solution according to the present invention keeps the mass balance and energy balance of the corresponding system practically unchanged and does not have any additional effect on the process as a whole. The present invention reduces capital costs and simplifies the installation of the plant.

Preferably, the fluid from the gaseous material stream withdrawn from the distillation device, which contains essentially methane and hydrogen, i.e., the overhead gas from the distillation device or from the first distillation unit of the distillation device, is used to at least cool the hydrocarbon mixture fluid from the first temperature level through the intermediate temperature levels to the second temperature level. This ensures efficient cooling of the respective fluid. In this case, in particular, additional cooling can be carried out in order to obtain the required low temperatures. The gaseous substance stream withdrawn from the distillation device is removed from it, for example, at a temperature of -150 to -160°C, in particular about -153°C. The corresponding temperature level in this step is also referred to as the fifth temperature level.

One of the intermediate temperature levels is preferably from -120 to -125°C, and one of the intermediate temperature levels from -140 to -145°C. The cold top gas from the fifth temperature level is preferably used to cool the fraction of the mixture of components that remained in the gaseous state during condensation upstream from the intermediate temperature level at -120 to -125° C. to the intermediate temperature level at -140 to -145° C, with heating of the upper gas to a temperature level of -120 to -130°C, for example, approximately -126°C.

The top gas is then preferably cooled in an expander to a temperature level of -150

- 5 041607 to -160°C, for example, about -157°C and is used to cool in appropriate condensation fractions of the mixture of components upstream, which remained in a gaseous state, to intermediate temperature levels, for example, from -120 to -125° C, -95 to -100°C, -74 to -79°C and -48 to

-53°C. In addition, an ethylene refrigerant is used to provide adequate cooling to intermediate temperature levels.

Preferably, the bottom liquid from the first separation unit is collected and transferred to the second separation unit to serve as a return flow or as a coolant in the second separation unit.

The method according to the present invention is particularly suitable for separating a mixture of components which is obtained from a cracked gas produced by a steam cracking process.

The present invention also provides a corresponding separation device. The separation device is designed to separate a mixture of components containing essentially hydrocarbons having two or two or more carbon atoms, and methane and hydrogen, and has a distillation device, a condenser and at least one expander. As regards the other components of the respective installation, reference is made to the above indications.

The present invention and embodiments of the present invention are more specifically explained with reference to the accompanying drawings.

Brief description of the drawings

In FIG. 1 shows a separation device for separating a mixture of components according to the prior art.

In FIG. 2 shows a separation device for separating a mixture of components in one embodiment of the present invention.

In FIG. 3 shows a separation device for separating a mixture of components in a second embodiment of the present invention.

In FIG. 4 shows a separation device for separating a mixture of components in a third embodiment of the present invention.

Detailed description of the drawings

In the drawings, the respective elements have the same reference designations and are not re-explained for the sake of clarity. In the following drawings, the invention is described with reference to the separation treatment of a mixture of components containing essentially hydrocarbons having two carbon atoms and methane and hydrogen. But it is also suitable for separating a mixture of components containing essentially hydrocarbons having two or more carbon atoms and methane and hydrogen.

In FIG. 1 shows a separation device for separating a mixture of components in an embodiment not related to the present invention. The separation device is generally designated 200 and is designed to separate a mixture of components containing essentially hydrocarbons having two carbon atoms, methane and hydrogen (ie, C2 minus fractions). The C2 minus fraction is fed to the separation device 200 in the form of a substance stream a.

The separation device 200 comprises a first heat exchanger 1, a second heat exchanger 2 and a third heat exchanger 3. The material stream a is first directed through the first heat exchanger 1 and cooled there. It is then fed into the first liquid separator 31. Cooling in the first heat exchanger 1 is carried out by separating the liquid condensate in the first liquid separator 31. It is withdrawn at the base of the first liquid separator 31 as a material stream b. The further use of the substance stream b is explained below.

The fraction of the flow a of the substance, which remained in the gaseous state in the first liquid separator 31, is sent as a flow from the substance through the second heat exchanger 2 and then fed into the second liquid separator 32. In the latter, the liquid condensate is also separated at the base and recovered as a flow d of the substance . The fraction of the flow from the substance, which still remained in the gaseous state, is sent as a flow e of the substance through the third heat exchanger 3 and then fed into the third liquid separator 33. In the latter, the liquid condensate is also separated at the base and recovered as the flow f of the substance. The fraction of the material stream e which is still in the gaseous state is sent to the expander 20 as a material stream k, expanded and at least partially liquefied. The two-phase flow thus formed is provided as a flow l of matter.

Separation apparatus 200 also includes a distillation column 50 which is operated with a riboiler 14, which will no longer be mentioned further, a heat exchanger which operates, for example, with a propylene stream which comes from other plant components. The distillation column 50 also includes two plate heat exchangers 15 and 16, the operation of which will be explained below. The distillation column 50 has two sections 51 and 52.

Due to the successive cooling of substance streams a, c, e and k, the condensates obtained respectively, which are obtained as substance streams b, d, f and l, have different contents of hydrocarbons having two carbon atoms, methane and hydrogen. More specifically, material stream l has a higher content of methane and hydrogen than material stream f, material stream f has a higher content of methane and hydrogen than material stream d, and material stream d has a higher content of methane and hydrogen. than the flow b of matter.

Streams b, d, f and l of the material are therefore fed into the distillation column 50 at different levels, which has injection devices suitable for this purpose, between trays, which are shown here in a very schematic way.

The gaseous substance stream n is withdrawn from the top of the distillation column 50 and expanded in the expander 21 and as a result substantially cooled or at least partially liquefied. The material stream n predominantly contains methane and hydrogen (this is thus the Schminus fraction). The liquefied flow n of the substance is passed through two plate heat exchangers 15 and 16 and used for cooling in it. Thereafter, the substance flow n is passed through the heat exchanger 2 and used to cool the gaseous substance flow c, and is passed through the heat exchanger 1 and used to cool the gaseous substance flow a. Thereafter, the material stream n, in particular after being used in the pre-cooler 99, is passed through two boosters 22 and 23 connected to expanders 20 and 21 and discharged from the plant as tail gas.

In the bottom of distillation column 50, a liquid condensate is separated, essentially consisting of hydrocarbons having two carbon atoms (ie, the C2 fraction). The condensate is removed as a stream of matter, heated in the first heat exchanger 1 and then, for example, sent to an additional separation device such as a C2 stripper.

The gaseous substance stream m1 is withdrawn in the gaseous state from the distillation column 50 in the first position, cooled in the plate heat exchanger 16 and thus at least partially liquefied and sent to the distillation column 50 in the second position as a reverse flow, i.e. sent back to distillation column 50 by gravity. The additional gaseous stream m2 of the substance is withdrawn in the gaseous state from the distillation column 50 in the third position, cooled in the plate heat exchanger 15 and thus at least partially liquefied and sent to the distillation column 50 in the fourth position as a reverse flow, i.e. sent back into the distillation column 50 by gravity, 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, in the plate heat exchangers 15 and 16, the liquefied material stream n is used to cool the material streams m1 and m2 and must be transported in a complicated way to the plate heat exchangers which are high. Mounting these plate heat exchangers 15 and 16 at the top of the distillation column 50 is inconvenient and costly.

In FIG. 2 shows a separation device 100 in one embodiment of the present invention. The separation device 100 includes the essential components of the separation device 200 shown in FIG. 1. They will not be described again.

In the separation apparatus 100, the distillation column is also provided with two sections. It is designated in this application as the device 10 distillation. Its two sections are designated in this application as the first distillation unit 11 and the second distillation unit 12. The separation device is provided with a condenser 13. In the separation device 100, the first distillation unit 11 is located above the second distillation unit 12. The condenser 13 is also located above the first distillation unit 11 . However, unlike the separation device 200 shown in FIG. 1, plate heat exchangers 15 and 16 were not used here. The material stream m, corresponding to the material stream m1 in the separation device 100, is cooled with an ethylene refrigerant in the condenser 13 and at least partially liquefied. The gaseous stream m of the substance is withdrawn from the upper region of the second distillation unit 12 and fed into the lower region of the first distillation unit 11 . Since the first distillation unit 11 and the second distillation unit 12 are separated from each other by a liquid support tray, the recycled material stream m serves to provide a return flow to the second distillation unit 12. There is no material flow corresponding to the material flow m2 in the separation device 100. Instead, a reverse flow is provided to the first distillation unit 11 as explained below.

Sequential cooling of C2 minus flow a is continued by means of a heat exchanger 4 for cooling the gaseous flow g of the substance and a heat exchanger 5 for cooling the gaseous flow i of the substance. In addition to the substance condensates or streams b, d, f and l, the condensates or substance streams h and j are separated in additional liquid separators 34 and 35. The fractions that remain in the gaseous state in each case are sent through the heat exchangers 4 and 5 in the form of streams g and i substances and cooled to intermediate temperature levels at -120 to -125°C (thread g) or from 140 to -145°C (thread i). Since the material stream j has a higher content of methane and hydrogen than the material stream h, and the material stream h has a higher content of methane and hydrogen than the material stream f, they are fed into the distillation apparatus 10 at different levels.

The material stream l is formed in the separation device 200 similarly to the material stream l in the separation device 100, but is at a significantly lower temperature due to the additional cooling in the heat exchangers 4 and 5. Due to the additional cooling, it is possible, in particular, to use the substance streams j and l as reverse flow to the first block 11 distillation. Therefore, liquefaction of the substance stream m2, as in the separation device 100, is not required, and therefore, as

- 7 041607 it was stated that heat exchangers 15 and 16 can be dispensed with.

Since, in the present invention, the gaseous substance stream n which is discharged at the top of the distillation apparatus does not need to be used for cooling in the plate heat exchangers and 16, it can be used for cooling in the heat exchangers 1, 2, 3, 4 and 5. In this way, the above-mentioned low temperatures.

In FIG. 3 shows a separation device 300 in yet another embodiment of the present invention. In this case, the prior art separation device is further provided with only a heat exchanger 4 and a liquid separator 34.

In FIG. 1-3, each heat exchanger 1-3 is cooled using additional material streams u, v, w and x. Streams u, v and w of the substance represent an ethylene coolant at different pressure levels; the material stream x is, for example, a recycled stream of ethane. The flow w respectively denotes the flow of ethylene refrigerant through the condenser 13.

In FIG. 4 shows a distillation unit 40 in yet another embodiment of the present invention. In this case, the condenser 13 is located between the first distillation unit 11 and the second distillation unit 12, with the first distillation unit 11 located above the condenser and the condenser 13 above the second distillation unit 12. Mass transfer is carried out in the form of a flow p of a substance and a flow q of a substance.

In addition, it would be possible to directly integrate the condenser 13 into the distillation unit 40, for example in the form of a shell-and-tube device or a unit between the first distillation unit 11 and the second distillation unit 12. Accordingly, internal elements such as a liquid seal could be dispensed with.

The table below lists the temperatures of selected material streams. Numbers in brackets are preferred temperature ranges; values after brackets refer to the preferred example.

Separation device 200 100 300 Flow a of the substance upstream of heat exchanger 1 (-25 to -35°С) -32°С (-25 to -35°С) -32°С (-25 to -35°С) -32°С Stream a of the substance downstream of heat exchanger 1 (from -45 to -55°C) -51°C (from -45 to -55°С) -51°С (from -45 to -55°C) -51°C Fluid with substance downstream of heat exchanger 2 (from -70 to -80°С) -76°С (from -74 to -80°C) -76°C (from -74 to -80°С) -76°С Substance flow downstream of heat exchanger 3 (-95 to -100°С) -97°С (-95 to -100°С) -97°С (-95 to -100°С) -97°С The flow g of the substance downstream of the heat exchanger 4 (from-115 to -125°C) -122°C (from -135 to -145°C) -143°C Flow i of the substance downstream of the heat exchanger 5 (from -135 to -145°C) -143°C Substance stream 1 downstream of expander 20 (from -112 to -118°C) -115°C (-155 to -165°С) -162°С (from -155 to -165°C) -162°C Flux η of matter after withdrawal (from -150 to -155°С) -152°С (from -150 to -155°С) -153°С (from -150 to -155°С) -153°С The flow of matter after withdrawal (from -35 to -45°С) -36°С (from -35 to -45°С) -36°С (from -35 to -45°С) -36°С

CLAIM

Claims (13)

CLAIM 1. A method for separating a mixture of components containing essentially hydrocarbons having two or two or more carbon atoms, methane and hydrogen, using a distillation device (10), in which the fluid (a, c, e, g, i ) from a mixture of components at the first pressure level is gradually cooled from the first temperature level through two or more intermediate temperature levels to the second temperature level with the release of condensates (b, d, f, h, j) from the fluid medium (a, c, e, g , i) at each of the intermediate temperature levels, the fluid (k) of the mixture of components, which remains in a gaseous state at the second temperature level, is cooled by expansion from the first pressure level to the second pressure level, which is lower than the first pressure level, to form a two-phase flow (1) containing liquid and gaseous parts, - 8 041607 the fluid from the condensates (b, d, f, h, j) and the fluid from the two-phase stream (l) are fed into the distillation device (10), which is operated at a second pressure level, where at least one liquid stream ( o) a substance containing essentially hydrocarbons having two or two or more carbon atoms, and a gaseous stream (n) of a substance containing essentially methane and hydrogen, is produced in the distillation device (10) and removed from the device (10 ) distillation, characterized in that the second temperature level is from -125 to -150°C, the distillation device (10) has a first distillation unit (11) and a second distillation unit (12), the first distillation unit (11) being operated at the third temperature level in its upper part, which is lower than the second temperature level, and the second distillation unit (12) is operated at the fourth temperature level in its upper part, which is lower than the second temperature level, and the liquid part of the two-phase flow, at least partially, is fed into the first th block (11) distillation. 2. Method according to claim 1, wherein the distillation apparatus (10) has a condenser (13) which is operated at a temperature level which is higher than the second temperature level. 3. The method according to claim 2, in which the fluid from the condensates (b, d, f, h, j) is fed at least partially into the first distillation unit (11) and the second distillation unit (12) of the device (10) distillation. 4. Method according to any one of claims 2 and 3, wherein the gaseous stream (m) of matter is withdrawn from the second distillation unit (12) of the distillation apparatus (10), cooled in a condenser (13) and used to provide a liquid reflux to the second unit (12) distillation. 5. The method according to any one of the preceding claims, wherein the liquid stream (o) of the substance is expanded from the second pressure level to a pressure level which is lower than 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 mixture of components is cooled using an ethane and/or ethylene cooler at different pressure levels from a first temperature level through intermediate levels to a second level temperature. 7. The method according to any one of the preceding claims, wherein the intermediate temperature levels comprise an intermediate temperature level of -48 to -53°C and/or an intermediate temperature level of -74 to -79°C and/or an intermediate temperature level at -95 to -100°C, and/or intermediate temperature level at -120 to -125°C, and/or intermediate temperature level at -140 to -145°C. 8. Process according to any one of claims 2 to 4, wherein the gaseous substance stream (m) is cooled in a condenser (13) with an ethylene cooler. 9. Process according to any one of claims 2 to 4 or 8, wherein the condenser (13) is located between the first distillation unit (11) and the second distillation unit (12). 10. The method according to any of the preceding claims, in which the fluid from the gaseous stream (n) of the substance that is removed from the distillation device (10) is used at least to cool the fluid (a, c, e, g, i) from hydrocarbon mixture from the first temperature level through the intermediate temperature levels to the second temperature level. 11. The method according to any of the preceding claims, wherein the fluid from the gaseous stream (n) of the substance that is withdrawn from the distillation device (10) is expanded in an additional expander (21) to a third pressure level which is lower than the second pressure level. 12. The method according to claim 11, in which the fluid from the gaseous stream (n) of the substance that is removed from the distillation device (10), after being used to cool the fluid (a, c, e, g, i) from the hydrocarbon mixture, is compressed , using compressors connected to the expander (20, 21) for compression. 13. The method according to any one of the preceding claims, which is used to separate a mixture of components that is obtained from a cracked gas obtained using a steam cracking process.