TW201518494A - Method and apparatus for producing hydrocarbon products - Google Patents

Abstract

A method for producing hydrocarbon products is proposed which comprises providing a C4 hydrocarbon stream (C4) that predominantly comprises branched and unbranched hydrocarbons each having four carbon atoms, and an n-C4 partial stream (n-C4), which predominantly comprises unbranched hydrocarbons with four carbon atoms and an iso-C4 partial stream (i-C4) which predominantly comprises branched hydrocarbons with four carbon atoms, from the C4 hydrocarbon stream (C4) or a stream derived therefrom. It is envisaged that at least part of the n-C4 partial stream (n-C4) or a stream derived therefrom should be cracked at a cracking severity at which not more than 92% of n-butane contained in the n-C4 partial stream (n-C4) or in the derived stream is converted.

Description

Method and apparatus for producing hydrocarbon products

The present invention relates to a method for producing a hydrocarbon product according to precharacterising clauses of separate items.

Methods and apparatus for steam cracking hydrocarbons are well known and described, for example, in the article "Ethylene" by Ullmann's Encyclopedia of Industrial Chemistry, since 2007. Announced on the Internet on April 15th, DOI 10.1002/14356007.a10_045.pub2.

US 3,922,216 A discloses a hydrocarbon stream comprising a hydrocarbon having two to five carbon atoms and a hydrocarbon having nine or more carbon atoms after removal of isobutene A method of combining hydrocarbon-like streams. The stream thus formed is subjected to a steam cracking treatment. EP 2 062 865 A1 discloses a process for the preparation of ethylene, propylene and isoprene from light hydrocarbons, wherein isobutene is self-selectively The butane fraction containing ethane is separated. Remainder can be reacted in one or more cracking zones of the steam cracking process. The same general type of processing is described in DE 28 05 179 A1, US 6,743,958 B2, US 5,523,502 A, US 2011/112345 A1 and US 4,091,046 A.

In recent steam cracking processes and equipment, there is an increasing tendency to use mild cracking conditions (see below), as this can improve the yield yielding specific so-called high value products such as propylene and butadiene ( Butadiene), as explained below. At the same time, however, the conversion of the furnace feed is reduced under mild cracking conditions, with the result that the compounds contained therein are found in relatively large amounts of cracked gas and result in "dilution of high value products". )".

The problem of the present invention is to solve this problem and to retain the advantages of mild cracking conditions while avoiding disadvantages. In particular, by reducing the dilution effect described above, it is desirable to increase the concentration and yield of high value products, particularly 1,3-butadiene.

The present invention discloses a process for producing a hydrocarbon product, the method comprising: providing a C4 hydrocarbon stream (C4) comprising at least 80% of branched hydrocarbons and linear hydrocarbons each having four carbon atoms; The hydrocarbon stream (C4) or a stream derived therefrom recovers an n-C4 split (n-C4) comprising at least 80% of a linear hydrocarbon having four carbon atoms and predominantly comprising a branch having four carbon atoms An iso-C4 split of the hydrocarbon (i-C4); and a degree of cracking of at least 50% and no more than 92% of the n-butane conversion contained therein to vapor cleave at least a portion of the n-C4 split (n-C4) ) or a stream derived from it.

The disclosure of the invention

The problem is solved by a method for producing a hydrocarbon product having the characteristics of a separate item. The preferred embodiments are the subject matter and the subject matter described below.

Before describing the features and advantages of the present invention, the basis and the terms used will be explained.

The steam cracking procedure is implemented almost exclusively in a tubular reactor on a commercial scale, wherein each reaction tube (in the form of a coil of a so-called coil) or a corresponding reaction tube group can be different Operate under lysis conditions. The reaction tubes or reaction tube groups operating under uniform cracking conditions and the tubular reactors that may also be employed are referred to as "cracking furnaces" in each of the following cases. As used herein, the term "cracking furnace" is thus a vapor cracking building block for exposing the furnace feed to the same or comparable cracking conditions. The steam cracking unit can comprise one or more cracking furnaces of this type.

As used herein, the term "furnace feed" means one or more liquid and/or gas streams fed to one or more cracking furnaces. Also, the stream obtained by the corresponding steam cracking procedure as explained below can be recycled to one or more cracking furnaces and reused as a furnace feed. A large number of hydrocarbon and hydrocarbon mixtures from ethane to gasoline up to a boiling point of typically 600 ° C are suitable for use as furnace feeds.

The furnace feed may consist of a so-called "fresh feed", ie prepared outside the equipment and consisting, for example, of one or more petroleum fractions, petroleum gas having two to four carbon atoms and/or petroleum gas condensate ( Condensate) the resulting feed. The furnace feed may also consist of one or more so-called "recycle streams", ie streams produced at the equipment itself and recycled to the corresponding cracking furnace. The furnace feed may also consist of a mixture of one or more fresh feeds having one or more recycle streams.

The furnace feed is at least partially converted at each cracking furnace and exits the cracking furnace as a so-called "feed gas", as will be explained hereinafter with reference to Figures 1A and 1B, a series of post-treatment steps. These post-treatment steps include, first, processing of the material gas, for example, by quenching, cooling, and drying to obtain a so-called "cracking gas." Occasionally, the material gas is considered to be a cracking gas.

The current process involves separating the cracked gas into some fractions, particularly depending on the different boiling points of the resulting composition. Abbreviations are used in the art to refer to the number of carbon atoms that a hydrocarbon contains predominantly or completely. Therefore, the C1 fraction is a fraction mainly or completely containing methane (but in some cases, hydrogen is also contained in some cases, and is also referred to as "C1 minus fraction"). The C2 fraction, on the other hand, mainly or completely comprises ethane, ethylene and/or acetylene. The C3 fraction mainly contains propane, propylene, methylacetylene and/or propadiene. The C4 fraction contains predominantly or completely butane, butene, butadiene and/or butyne, while individual isomers may be present in varying amounts depending on the source of the C4 cut. The same applies to C5 fractions and higher fractions. Many such fractions can also be combined in a program and/or under a heading. For example, the C2+ (C2plus) fraction contains predominantly or completely hydrocarbons having two or more carbon atoms and the C2-(C2minus) fraction contains predominantly or completely hydrocarbons having one or two carbon atoms.

In the language of the art, liquid and gas streams may be rich or absent in one or more compositions on a molar, weight and volume basis, and "rich" means at least 90%, 95%, 99%. , 99.5%, 99.9%, 99.99% or 99.999%, and "poor" means up to 10%, 5%, 1%, 0.1%, 0.01% or 0.001%. The term "mainly" means at least 50%, 60%, 70%, 80% or 90% or corresponds to the content "rich". In the language of the art used herein, liquid and gas streams may also be enriched or depleted in one or more compositions relative to the starting mixture from which the liquid or gas stream is obtained (starting) The corresponding content in the mixture). Depending on the amount of starting mixture, if at least 1.1, 1.5, 2, 5, 10, 100 or 1000 times the amount of the corresponding constituent is included, the liquid or gas stream is "enriched" if it contains A maximum of 0.9 times, 0.5 times, 0.1 times, 0.01 times, or 0.001 times is "consumed".

The stream can be derived from another stream by, for example, dilution, concentration, enrichment, consumption, separation or reaction of any desired composition, either via a separation step or in combination with at least one other stream. The derivatized stream can also be formed by dividing the initial stream into at least two split streams, each stream or a stream remaining after the separation step of the other stream being a derivative stream of this type.

The "cracking conditions" mentioned above in the cracking furnace include, in particular, the partial pressure of the furnace feed, which can be obtained by adding different amounts of steam and the pressure selected in the cracking furnace, and the dwell time in the cracking furnace. It is affected by the temperature and temperature profiles used. The geometry and configuration of the furnace also play a role. To produce ethylene, the cracking furnace operates at a furnace inlet temperature of, for example, 500 to 680 ° C and a furnace outlet temperature of 775 to 875 ° C. The "furnace inlet temperature" is the temperature of the gas stream at the beginning of the reaction tube, and the "furnace outlet temperature" is the temperature of the gas stream at the end of the reaction tube. Usually the latter is the highest temperature at which the gas stream involved is heated. It is mixed with the furnace charge at a pressure of typically 0.25 to 0.85 kg/kg at a furnace outlet measuring 165 to 225 kPa. The particular values used will depend on the particular furnace feed used and the desired cracking product.

When the values mentioned affect each other at least in part, the term "degree of cracking" applies to the conditions of the cleavage. For liquid furnace feeds, the degree of cracking can be described in terms of the weight (kg/kg), the ratio of propylene to ethylene (P/E) or the ratio of methane to propylene (M/P) in the cracked gas. The ratio of P/E and M/P is directly dependent on the temperature, but unlike the actual temperature in the cracking furnace or the true temperature of the cracking furnace outlet, it can be measured and used more accurately, for example as in the corresponding conditioning process. Control variables. However, the P/E ratio is limited to the degree of cracking of a compound that is used to indicate a gas furnace feed or has two to four carbon atoms.

For the gas furnace feed, the reaction or conversion of the specific composition of the furnace feed can be specified as a measure of the degree of cracking. The term reaction or transformation is used in a conventional manner in the art (see, for example, the article "Ethylene" in the Ullmann Encyclopedia of Industrial Chemistry mentioned above). Especially for the C4 fraction or C4 split used in this case, it is very useful to describe the degree of cracking based on the conversion of key components such as n-butane and isobutane.

If n-butane is converted over 92% in the corresponding fraction, the degree of cracking or cracking conditions is "severe". Under even more severe cleavage conditions, n-butane is selectively converted over 93%, 94% or 95%. Typically, there is no 100% n-butane conversion. The upper limit of "severe" cracking or cracking conditions is therefore, for example, 99%, 98%, 97% or 96% n-butane conversion. On the other hand, if the n-butane conversion is less than 92%, the degree of cracking or cracking conditions is "mild". There are less than 91%, less than 90%, less than 89%, less than 88% or less than 87% n-butane conversion, and there is always a milder degree of cracking or cracking conditions. In less than 86% n-butane conversion, the degree of cracking or cracking conditions is referred to as "very mild." Very mild degrees of cracking or cleavage conditions also include, for example, less than 85%, 84%, 83%, 82%, 81%, 80%, 79%, 78%, 77%, 76%, 75%, 70% Or 65% and more than 50% or 60% n-butane conversion.

When the isobutane conversion in the corresponding fraction exceeds 91%, the degree of cracking or cracking conditions is also "violent". Isobutane is selectively converted over 92%, 93% or 94% under even more severe cleavage conditions. Usually, there is also no 100% isobutane conversion. The "violent" degree of cracking or the upper limit of the cleavage conditions is thus for example converted at 99%, 98%, 97% or 96% isobutane. However, if the isobutane conversion is less than 91%, the degree of cracking or cracking conditions is "mild". With less than 90%, less than 89%, less than 88%, less than 87%, or less than 86% isobutane conversion, more moderate cracking or cracking conditions are increasingly available. In less than 83% isobutane conversion, the degree of cracking or cleavage conditions is referred to herein as "very mild." Very mild cracking or cracking conditions also include, for example, less than 82%, 81%, 80%, 79%, 78%, 77%, 76%, 75% or 70% and more than 45% or 50% isobutane Conversion.

As mentioned above, the cracking or cracking conditions mentioned above are particularly relevant to the furnace outlet temperature at the end of the reforming tube or to the cracking furnace used. The higher the temperature, the more "clear" the cracking or cracking conditions and the lower the temperature, the more "melting" the cracking or cracking conditions.

It should also be understood that the conversion of the other compositions need not be the same as the conversion of n-butane and isobutane. If, for example, 1-butene and 2-butene are cleaved together with n-butane, they will generally be converted to a greater extent than n-butane. Conversely, if cleaved with isobutane, the isobutene will be converted to a lesser extent than isobutane. The percent conversion of the key composition, in this case n-butane or isobutane, is therefore related to the furnace outlet temperature and the respective percent conversion of the other constituents of the feedstock. The furnace outlet temperature, among other things, is in turn dependent on the cracking furnace. The difference between the respective percent conversions is based on a number of other factors. Advantages of the invention

The present invention begins with a process for the manufacture of a hydrocarbon product, wherein it is provided primarily comprising, i.e., at least 80%, having four carbon atoms (hereinafter also referred to as a C4 fraction or a C4 hydrocarbon stream, abbreviated as C4, according to the usual terminology, Hydrocarbonated hydrocarbons of branched hydrocarbons and linear hydrocarbons are also used in the drawings. In this respect, the process according to the invention corresponds to a conventional process for producing a hydrocarbon product, for example via steam cracking, wherein this type of C4 hydrocarbon stream is separated from the cracked gas which has been selectively treated further. This can occur in conventional equipment called debutanizers (although this also separates all other hydrocarbons having four carbon atoms from the corresponding hydrocarbon stream). This detail is shown in the article "Ethylene" of the Ullmann Encyclopedia of Industrial Chemistry mentioned above and is described with reference to Figures 1A and 1B.

However, the invention is not limited to the use of C4 hydrocarbon streams provided via steam cracking and subsequent process steps, but is equally applicable to, at least in part, other methods, such as C4 hydrocarbons produced via refinery processes. Class flow. For example, the present invention may use a C4 stream that has not been previously steam cracked and that is only subsequently fed to the corresponding vapor cracking procedure. These may be, for example, petroleum fractions, petroleum gas compositions having two to four carbon atoms, petroleum gas condensates and the like or products obtained from a refinery conversion process. In particular, this type of C4 hydrocarbon stream can be subjected to one or more procedures via a method of reacting and/or isolating a compound contained in a C4 hydrocarbon stream.

The present invention contemplates recovering a linear hydrocarbon having predominantly, i.e., at least 80%, four carbon atoms from the C4 hydrocarbon stream or a stream derived therefrom (i.e., an n-C4 compound, thus referred to as n a split of the -C4 fraction or n-C4 split, abbreviated as n-C4, n-C4 is also used as a reference symbol in the figure; and a split of a branched hydrocarbon having predominantly four carbon atoms (ie , iso-C4 compound, therefore referred to as iso-C4 fraction or iso-C4 shunt; abbreviated as i-C4, i-C4 is also used in the drawings as a reference symbol).

The present invention contemplates cleavage of at least a portion of the n-C4 split or a stream derived therefrom from n-butane contained in the n-C4 split being converted to a degree of cracking of at least 50% and less than 92%. Therefore, mild or very mild cracking or cracking conditions are used. These may also correspond, for example, to less than 90%, 88%, 86%, 84%, 82%, 80%, 78%, 76%, 74%, 72%, 70% or 65%, but for example more than 50% or 60% % n-butane conversion. Under the mild conditions of the cleavage, more desired products, such as butadiene and propylene, can be obtained relative to the fresh feed to increase yield and improve product spectrum.

"Cleavage" comprises selectively, after previously combining to form a combined stream, a stream (or a corresponding portion thereof) which is split or derived from n-C4, either separately or together with other streams, is passed to the cleavage as defined herein before. The furnace is removed from the cracking furnace.

Advantageously, the iso-C4 comprising the iso-C4 split is included, for example, before the corresponding split is sent to the cracking furnace (see below) and/or before it is removed as a product and/or before further separation of the iso-C4 split. The compound is also at least partially reacted via a skeletal isomerisation procedure to form an n-C4 compound. The corresponding skeletal isomerization procedure involves the use of suitable catalysts and reaction conditions, as disclosed, for example, in US Pat. No. 6,743,958 B2 or US Pat. No. 6,916,448 B2.

The skeletal isomerization can be achieved using an alumina catalyst wherein gamma-alumina can be used as the adsorbent, as a catalyst support and/or as the catalyst itself. For example, activated and/or vapor treated alumina can also be used, as described in US 3 558 733 A. Furthermore, compounds comprising titanium or boron, in particular η- or γ-alumina, can be used, as described in US 5 321 195 A and US 5 659 104 A. Other compounds which can be used are aluminum halides, as described, for example, in US 2 417 647 A, bauxite or zeolite. Molecular sieves of the microporous structure are also known from the teachings of EP 0 523 838 A1, EP 0 501 577 A1 and EP 0 740 957 A1. These can also form the active phase of the catalyst. The alumina-based catalyst is usually used in the presence of water at a temperature of 200 to 700 ° C and a pressure of 0.1 to 2 MPa, particularly at a temperature of 300 to 570 ° C and a pressure of 0.1 to 1 MPa. Other reaction conditions for skeletal isomerization can be inferred from the publications mentioned above.

The n-C4 compound obtained via skeletal isomerization also facilitates the mild cleavage conditions previously mentioned, in particular it can be combined with the n-C4 split from the n-C4 hydrocarbon stream according to the present invention. The unconverted iso-C4 compound (initial) during skeletal isomerization may be at least partially removed from the corresponding device, subjected to vigorous lysis conditions and/or again to any of the procedures previously or hereinafter described. In particular, it is advantageous to carry out the described skeletal isomerization of at least some of these iso-C4 compounds until a complete conversion is achieved. It may also be advantageous to combine the stream comprising the n-C4 compound and the (unconverted) iso-C4 compound obtained from the skeletal isomerization with the C4 hydrocarbon stream as the starting stream. In this manner, the resulting n-C4 compound can be isolated using the same equipment provided to recover the n-C4 split and iso-C4 split. The introduction can be carried out at any desired point, i.e., upstream or downstream of any desired procedure performed prior to recovery of the n-C4 split and iso-C4 split, such that the resulting compounds in skeletal isomerization can also be used.

Vapor cracking of C4 fractions from different sources is well known in the art. The cleavage results can be reliably predicted using available tools. Conventionally, it exists as a mixture of branched and linear C4 compounds. In the previously mentioned fresh feed, it mainly comprises paraffinic compounds, and in the recovery stream from the steam cracking procedure or other processing (for example, from refining) products, which mainly comprise olefinic compounds ( Olefinic compounds).

Especially when under mild cleavage conditions or in a high proportion of C4 freshly fed pyrolysis naphthas, the proportion of C4 fractions obtained from the corresponding pyrolysis gases is also large, and in particular has a relatively low concentration. 1,3-butadiene and other high value products selectively extracted from the C4 fraction. As a result, the recovery of 1,3-butadiene is uneconomical.

Especially when steam cracking hydrocarbons under abnormally mild cracking conditions, the amount of some product fractions is thus greatly increased, as mentioned, and the presence of high value products is reduced in concentration (dilution effect). This makes the recovery of high value products more difficult or more expensive.

The present invention is based on the discovery that the branched C4 compound in the cracking furnace causes the formation of 1,3-butadiene to a lesser extent due to its structure. The formation of relatively high methane from such compounds is inevitable, especially when the branched C4 compound is recovered until complete conversion. Therefore, if the C4 hydrocarbon stream of the bulk branched and linear C4 compound is cleaved under mild or even very mild conditions, this results in a relatively large stream of C4 fraction with a low concentration of 1,3-butadiene. .

This effect is offset by the present invention, which is preceded by steam cracking, for example, by distillation and cracking of a C4 hydrocarbon stream or an n-C4 compound mainly contained therein, but preferably not prior to the iso-C4 compound. The n-C4 split is obtained from the C4 hydrocarbon stream under specific mild conditions. As already explained, the iso-C4 compound which is isolated in the iso-C4 split and which is still present after the subsequent procedure such as skeletal isomerization can be obtained at least in part as a product.

Advantageously, however, the iso-C4 split or stream derived therefrom, such as a stream or split stream present downstream of the hydrotreating (see below) or skeletal isomerization procedures, is at least partially cracked with a high degree of cracking. In such cases, very severe conditions were used in comparison to the particularly mildly cleaved n-C4 split.

Thus, advantageously, the iso-C4 split or stream derived therefrom is at least partially cracked with a degree of cracking of isobutane contained therein exceeding 91%. "Cleavage" as used herein also includes selectively splitting or deriving a stream of iso-C4 (or a corresponding portion thereof) separately or in combination with other streams, as previously selected to form a binding stream, according to previous A defined cracking furnace is provided and the cracked gas is removed from the cracking furnace.

The degree of cleavage used to cleave the iso-C4 split is thus higher than the degree of cleavage used to cleave the n-C4 split. The terms "higher" and "lower" are relative to each other. Advantageously, therefore, at least a portion of the iso-C4 split or stream derived therefrom is cracked at a first degree of cracking and at least a portion of the n-C4 split or stream derived therefrom is cracked at a second cracking degree, the first cracking The degree is higher than the second degree of cracking, or the second degree of cracking is lower than the first degree of cracking.

Thanks to the invention, the disadvantage of mild cracking is reduced or completely eliminated, while reducing the amount of C4 fraction, and as a result, the concentration of the target product, in this case in particular 1,3-butadiene The system has been added. Reduce the energy of specific extraction.

The core of the invention therefore comprises minimizing the overall C4 fraction by selective use of mild, especially very mild, cleavage conditions for the n-C4 compound, in such a way that, for example, relative to 1,3-butadiene High selectivity. Advantageously, this is controlled to increase the structural transformation of the iso-C4 compound, for example by vigorous cleavage after pre-separation of the n-C4 compound.

The present invention further contemplates that in order to improve the separation of iso-C4 and n-C4 compounds, at least a portion of the C4 hydrocarbon stream, i.e., a hydrocarbon stream comprising predominantly branched hydrocarbons having four carbon atoms and linear hydrocarbons, Any 1-butene present is reacted to form 2-butene. A hydroisomerisation procedure is used for this purpose.

A stream of C4 hydrocarbon stream or at least a stream derived from a C4 hydrocarbon stream (i.e., separated from other streams, combined, etc.) is fed to at least one hydroisomerization reactor. A C4 hydrocarbon stream enriched in 2-butene while depleting 1-butene is obtained, wherein other components can also be reacted via a hydroisomerization procedure. For example, any residual traces of butadiene can be eliminated in this manner. However, the composition that has not been reacted via the hydroisomerization procedure is still present in this stream. This type of stream is also referred to as the "offstream" of the hydroisomerization process (or for the hydroisomerization reactor therein). It is a stream derived from a C4 hydrocarbon stream.

It may also be advantageous to feed at least one other stream, in particular a stream containing butyne (C4-acetylene) and/or a hydrocarbon having five carbon atoms, before or after hydroisomerization or another procedure. It is intended to be a C4 hydrocarbon stream mainly comprising branched hydrocarbons each having four carbon atoms and a linear hydrocarbon. For example, a C5 compound that is co-extracted during butadiene extraction (see below) can be used, and thus it is used well.

This hydroisomerization ensures conversion of 1-butene to 2-butene in the corresponding C4 hydrocarbon stream, thus making it significantly easier to separate iso-C4 from the n-C4 compound. This is due to the fact that 2-butene or its two isomers (cis-2-butene: 3.72 °C at atmospheric pressure) compared to 1-butene (-6.26 °C at atmospheric pressure); The result of a significantly higher boiling point of butene: 0.88 ° C under pressure. In contrast, 1-butene cannot be separated from the isobutylene having almost the same boiling point as 1-butene (-6.9 ° C under pressure) because of its boiling point. The basic concept of the invention is to isolate iso-C4 compounds which are detrimental to very mild cleavage conditions prior to mild cleavage, so that hydroisomerization can be achieved more simply and inexpensively. Further, C4-acetylene can be reacted via hydroisomerization to form n-butene.

Hydroisomerization procedures are known per se and are described, for example, in EP 1 871 730 B1, US 2002/169346 A1, US Pat. No. 6,420,619 B1, US Pat. No. 6,075,173, and WO 93/21137 A1. In such a procedure, the corresponding stream is typically passed through a hydroisomerization reactor in the presence of a hydroisomerization catalyst. The hydroisomerization reactor is typically carried out as a solid bed reactor. Preferably, the hydroisomerization procedure maximizes the conversion of 1-butene to 2-butene. However, among other things, the actual conversions are based on economic considerations.

It is particularly advantageous if the iso-C4 is split, i.e. consists essentially of a branched hydrocarbon having four carbon atoms, or a stream derived therefrom, optionally at least partially hydrotreated prior to subsequent steam cracking. . During this procedure, the isobutene (olefin) present is at least partially reacted to form isobutane (alkane). In subsequent cleavage procedures, i.e., at higher degrees of cracking, isobutane can react more readily or form readily utilisable products. This makes it possible to further reduce the amount of the C4 fraction and thereby concentrate the target product, as mentioned above.

For hydrogenated and hydroisomerized olefins or hydrocarbon mixtures containing olefins, many catalytic processes are known from the prior art and can be used within the scope of the present invention. A hydration catalyst has one or more elements of the sixth, seventh or eighth group of the periodic table in an elemental or combined form as an active hydrogenation component. Usually, the noble metal of the eighth group in the form of an element is used as a hydroisomerization catalyst. It can be doped with different additives to affect the performance of a particular catalyst, such as useful life, resistance to specific catalyst poisons, selectivity or regenerability. The hydrogenation and hydroisomerization catalysts usually comprise an active ingredient on a support, such as mordenites, zeolites, Al ₂ O ₃ modifications, cerium oxide modifiers (SiO _{2 ).} Modifications and so on.

Generally, a wide range of hydrogenation for olefins uses a reaction temperature of from 150 to 250 °C. Hydroisomerization is achieved at significantly lower temperatures. At these lower temperatures, the thermodynamic equilibrium is towards internal olefins, in this case 2-butene.

The above-described procedural variants may encompass from the n-C4 split or its corresponding proportions according to the invention and/or streams derived therefrom selectively along with at least one cracked gas stream produced during fresh steam feed cracking. The above-described C4 hydrocarbon stream is at least partially formed.

However, the C4 hydrocarbon stream can also be formed, at least in part, from a cracked gas obtained by steam cracking fresh feed or a fresh feed from uncleaved. These choices make it possible to make very flexible adjustments to the desired level of hydrocarbon stream for individual C4 compounds.

Vapor cracking within the scope of the invention facilitates the use of 0.4 kg/kg of steam at the same or different values in the cracking furnace used, in particular 0.2 to 0.7 kg/kg, for example 0.3 to 0.5 kg/kg. . Corresponding values are also particularly suitable for other cracking feeds.

If different degrees of cracking are used, it may be advantageous to adjust for at least one cracking furnace each provided with at least one other furnace feed. For example, a cracking furnace designed for a corresponding throughput can be used, which operates at a lower degree of cracking, and in which, in addition to the n-C4 stream, the "regular" fresh feed is also gently cracked. . In the corresponding variant of the program, the iso-C4 stream can also be self-cracked in a cracking furnace operating at a higher degree of cracking. However, in some cases, such as when a similar cracking furnace is used for cost reasons, it is more sensible to violently crack the iso-C4 stream along with the fresh feed.

It will be understood that if the entire iso-C4 stream is formed, it does not require cleavage under severe conditions. It is also possible to cleave a portion of the iso-C4 stream under mild conditions. However, at least some will violently cleave, thus achieving a corresponding reduction in the amount, as previously explained.

As mentioned above, a particular object of the invention is to improve the process in which 1,3-butadiene is separated from a hydrocarbon stream. All conventional methods for extracting 1,3-butadiene are suitable for this purpose.

If, after separation of the 1,3-butadiene, for example prior to hydroisomerization, the isobutylene contained in the hydrocarbon stream is at least partially reacted to form a tert-butylether and it is also extracted, Other advantages are obtained. The preparation of methyl-tert-butylether (2-methoxy-2-methylpropane (MTBE)) is a well-known principle. MTBE is industrially produced from an isobutene and methanol from which a hydrocarbon stream is added as an acid catalyst. MTBE is mainly used as an anti-knocking agent, but it is also increasingly used as a solvent and extractant in organic chemistry. Ethanol produces ethyl-tert-butylether. Other alcohols can also be used.

The device according to the invention is also designed to facilitate the implementation of the procedure as previously described.

At least one separation device advantageously comprises at least one separation column, and the steam cracking unit advantageously comprises at least two cracking furnaces designed to operate at different degrees of cracking.

The invention is explained below with reference to the prior art in relation to the prior art. Detailed description of the schema

Figure 1A shows in a schematic flow chart the process of producing a hydrocarbon according to the prior art. The core of the process here is that the vapor cracking procedure 10 can be carried out using one or more cracking furnaces 11 to 13. Only the operation of the cracking furnace 11 will be described hereinafter, and the other cracking furnaces 12 and 13 can be operated in a corresponding manner.

The cracking furnace 11 feeds with stream A as a furnace feed, and this can be at least partially a fresh feed, so-called source from outside the plant, and at least partially the recovery stream obtained in the process itself, as in the next Explained in the text. Other cracking furnaces 12 and 13 can also be fed to the corresponding streams. Different streams can also be fed to different cracking furnaces 11 to 13, one stream can be divided between many cracking furnaces, or a plurality of split streams can be combined to form, for example, stream A as one of the cracking furnaces 11 to 13 A combined stream.

As a result of the steam cracking of the steam cracking procedure 10, a feed gas stream B which has occasionally been referred to as a cracked gas stream at this time is obtained. The raw gas stream B is prepared in a series of preparative steps (not shown) of the preparation procedure 20 for so-called oil quench, for example, pre-fractionation, compression, further cooling, and drying.

Corresponding to the treated stream B, the actual cracked gas C is then subjected to a separation procedure 30. Some fractions are obtained in this procedure, as explained above, and are named according to the number of carbon atoms of the hydrocarbons which they mainly contain. The separation program 30 shown in Fig. 1A operates according to the principle of "Demethanizer First", and the first diagram BB shows the principle according to "Deethanizer First". Separation program.

In the separation procedure 30, a C1- or C1minus fraction of hydrogen (referred to as C1) may also be included, unless it has been previously removed, as a gas from the cracking gas C in the first separation unit 31 (so-called demethanizer) The form is first separated. It is usually used as a combustion gas. The liquid C2plus fraction (reference symbol C2+) is maintained for delivery to a second separation unit 32 (so-called deethanizer).

At the second separation unit 32, the C2 fraction (reference symbol C2) is separated from the C2plus fraction in gaseous form and subjected to, for example, a hydrotreating procedure 41 to convert any acetylene present to ethylene. The C2 fraction is then separated in the C2 separation unit 35 into ethylene (reference symbol C ₂ H ₄ ) and ethane (reference symbol C ₂ H ₆ ). The latter can be subjected to the vapor cracking process 10 again as a recovery stream D in one or more cracking furnaces 11 to 13. In the illustrated example, recycle streams D and E are fed to stream A. The recovery streams D and E and stream A can also be fed to different cracking furnaces 11 to 13.

At the second separation unit 32, the liquid C3plus fraction (reference symbol C3+) is maintained to be delivered to the third separation unit 33 (so-called depropanizer). In the third separation unit 33, the C3 fraction (reference symbol C3) is separated from the C3plus fraction and another hydrotreating procedure 42 is performed to convert the propylene contained in the C3 fraction to propene. The C3 fraction is then separated in a C3 separation unit 36 into propylene (reference symbol C ₃ H ₆ ) and propane (reference symbol C ₃ H ₈ ). The latter can be subjected to a vapor cracking process 10 again as a recovery stream E, either alone or in combination with other streams, in one or more cracking furnaces 11 to 13.

At the third separation unit 33, the liquid C4plus fraction (reference symbol C4+) is maintained to be delivered to the fourth separation unit 34 (so-called Debutanizer). In the fourth separation unit 34, the C4 fraction (reference symbol C4, referred to herein as the C4 hydrocarbon stream) is separated from the C4plus fraction. The liquid C5plus fraction is left (reference symbol C5+).

It will be understood that all of the fractions described herein may also be subjected to suitable post-treatment steps. For example, 1,3-butadiene can be separated from the C4 hydrocarbon stream, as explained below. Also, other recycle streams can be used which can perform a vapor cracking procedure 10 similar to recycle streams D and E.

Figure 1B shows, in schematic flow chart form, an alternative process process for the production of hydrocarbons via steam cracking according to the prior art. Again, the core of the process is that the vapor cracking procedure 10 can be accomplished using one or more cracking furnaces 11-13. The cracking gas C herein is subjected to an alternative separation procedure 30 in accordance with the principle of the "first deethanizer" relative to the method illustrated in Figure 1A.

In the separation treatment 30, the C2minus fraction (reference symbol C2-) may mainly contain methane, ethane, ethylene, and acetylene, and if not eliminated, the associated hydrogen is first in the first separation unit 37 from the cracked gas C in gaseous form. Separated. The bulk C2minus fraction is subjected to a hydrotreating procedure 43 to convert the contained acetylene to ethylene. The C1 fraction is then separated from the C2minus fraction at C2minus separation unit 38 and further used as described above. The C2 fraction remains separated into ethylene and ethane in the C2 separation unit 35 as described above. The latter can be subjected to the vapor cracking process 10 again as a recovery stream D in one or more cracking furnaces 11 to 13. In the first separation unit 37, the liquid C3plus fraction is maintained in the separation units 33 to 36 and the hydrotreating unit 42, as explained with reference to Fig. 1A.

Often the skilled person will be familiar with many other program variants, such as the article "Ethylene" from the aforementioned Ullmann encyclopedia of industrial chemistry, which differs from the preparation of cracking gas C and/or the separation procedure used.

The C4 hydrocarbon stream may also be subjected to a vapor cracking process 10 in part in one or more cracking furnaces 11 to 13 as a corresponding recovery stream. Especially when mild cracking conditions are used, however, the branched C4 compound (iso-C4 compound) contained in the C4 hydrocarbon stream may be converted to a lesser extent than the n-C4 compound and thus is once again found in large quantities. Cracking gas stream C. The iso-C4 compound is thus circulated multiple times through the corresponding device. The result of this mild vapor cracking procedure is a significant increase in the amount of some product fractions, in this case iso-C4 compounds, and the concentration of high value products present as a result of the dilution effect is reduced. In the case, it is, for example, 1,3-butadiene. This makes recycling high value products more difficult and expensive. In other words, the iso-C4 compound does not actually contribute to the formation of 1,3-butadiene due to its structure. A relatively large amount of mostly worthless methane formation is inevitable, especially when the iso-C4 compound is recovered until complete conversion.

Thus, if the C4 hydrocarbon stream is cleaved with an iso-C4 compound, regardless of its source, this again leads to a relatively large amount of C4 fractionation with a low 1,3-butadiene concentration under mild or very mild conditions. product.

Figure 2 is a schematic flow diagram showing the process of producing a hydrocarbon via steam cracking in accordance with an embodiment of the present invention. Here again, the core of the process is a vapor cracking procedure 10 that can be carried out using cracking furnaces 11 to 13. To illustrate the general availability of the process shown herein, recovery of the C4plus fraction from cracked gas C is not shown; however, this may be as shown in Figure 1A or Figure 1B or in any other field of art. A customary way to achieve. In the examples shown herein, the C4plus fraction is provided to a separation unit 34 as described above. However, the use of this separation unit 34 can be dispensed with if no or only some C5plus hydrocarbons are formed in the vapor cracking procedure. However, C4 hydrocarbon streams can also be supplied from outside the equipment, for example, from refineries.

For example, the C4 hydrocarbon stream obtained from separation unit 34 can be fed to a 1,3-butadiene-recovered 1,3-butadiene recovery unit 50, referred to herein as BD. Here, 1,3-butadiene represents one of the desired high-value products, and the remaining composition of the C4 hydrocarbon stream, C4, is a major low economic value and "dilutes" the desired 1,3-butadiene. It is more difficult to extract.

According to the illustrated embodiment, the present invention contemplates separating iso-C4 and n-C4 compounds (reference symbols i-C4 and n-C4), ie, branched and linear C4 compounds, from each other in separation unit 39, and recovering corresponding Diversion. The shunt that primarily comprises the iso-C4 compound is referred to herein as the iso-C4 shunt. This may be additionally recovered as recovery stream H and also once again subjected to steam cracking procedure 10 or from another steam cracking procedure 10. Preferably, the iso-C4 hydrocarbon stream is subjected to vigorous cracking conditions, and in this case, the cracking furnace 12 is designed for use in this case. Hydrogenation of isobutylene can be achieved in advance as described by block 44. Alternatively, after it has also been previously subjected to the preparation procedure 20, the stream G removed from the cracking furnace 12 may be added, for example, to the cracking gas C.

A partial vaporization process comprising an n-C4 compound and referred to herein as an n-C4 hydrocarbon stream can be recovered as recovery stream F and again subjected to a steam cracking procedure 10 or additionally from this vapor cracking procedure 10 . Preferably, the n-C4 compound is subjected to mild to very mild cracking conditions, and the cracking furnace 13 is designed for use in this case. Alternatively, after the latter has also been subjected to the preparation procedure 20 in advance, the stream I removed from the cracking furnace 13 may be added, for example, to the cracking gas C.

Figure 3 shows, in schematic flow chart form, a process for the manufacture of hydrocarbons via steam cracking in accordance with another embodiment of the present invention. Again, the core of the treatment is a vapor cracking procedure 10 that can be implemented using cracking furnaces 11 through 13. Here too, in order to illustrate the general availability of the method shown herein, the recovery of the C4plus fraction from the cracked gas C is not shown; however, this may be as known in the art as shown in FIG. 1A or FIG. 1B. Know any other way to achieve it. And in the examples shown herein, the C4plus fraction is provided to the separation unit 34 as described above. Again, if no or only some C5plus hydrocarbons are formed in the vapor cracking procedure, the use of this separation unit 34 may also be eliminated. However, C4 hydrocarbon streams can also be supplied from outside the facility, for example, from refineries.

For example, the C4 hydrocarbon stream obtained from separation unit 34 can be fed to a 1,3-butadiene-recovered 1,3-butadiene recovery unit 50, referred to herein as BD. In this context, 1,3-butadiene represents one of the desired high value products, and the remaining composition C4 of the C4 hydrocarbon stream is primarily of low economic value and "dilutes" the desired 1,3-butadiene. It is more difficult to extract.

In accordance with the illustrated embodiment, the present invention provides a C4 hydrocarbon stream that is provided to a hydroisomerization reactor 60 downstream of the butadiene recovery unit 50, again labeled C4, and 1-butene. It is at least partially converted to form 2-butene.

Here again, it is envisaged to separate the iso-C4 and n-C4 compounds from each other in the separation unit 39 and to obtain the corresponding splits (n-C4 split and iso-C4 split). The invention may also include only the recovery of the n-C4 split while the iso-C4 split or the compound contained therein may be external to the output device.

The iso-C4 split can be recovered as recovery stream H and subjected to vapor cracking procedure 10 or another vapor cracking procedure can be performed from this vapor cracking procedure 10, as explained above. Hydrogenation of isobutylene can also be achieved, as described by block 44. The n-C4 split can also be recovered as recycle stream F and subjected to a vapor cracking procedure 10 or another vapor cracking procedure additionally implemented from this vapor cracking scheme 10, as explained above.

Figure 4 shows, in schematic flow chart form, a process for the manufacture of hydrocarbons via steam cracking in accordance with another embodiment of the present invention.

In contrast to Figure 3, an additional unit 70 is explicitly shown which is designed to separate unwanted co-extracted components, such as C4-acetylene, for example during the extraction of butadiene from the butadiene recovery unit 50 (see C ₄ H ₆ ) and fed to the hydroisomerization reactor 60. In a practical embodiment, this unit 70 is integrated into the butadiene recovery unit 50, and in particular, and can also be provided as part of the butadiene recovery unit 50 as shown in FIG. Alternatively or additionally, it may be provided to at least partially react with isobutylene in a C4 hydrocarbon stream after separation of 1,3-butadiene to form methyl tert-butyl ether, and also from a hydrocarbon stream (not shown) A device 80 for separating methyl tert-butyl ether. Alternatively, ethyl tert-butyl ether can also be formed.

Figure 5 is a schematic flow diagram showing the process of producing hydrocarbons via steam cracking in accordance with another embodiment of the present invention. Again, the core of the process is that the vapor cracking procedure 10 can be implemented using cracking furnaces 11 through 13. For further details of the method and the device used, reference is made to the description of Figures 2 through 4.

The iso-C4 split from separation unit 39 is provided here to a skeletal isomerization reactor 90 designed to react at least some of the iso-C4 compounds contained in the iso-C4 split to form the corresponding n-C4 compound. At this stage, or in a subsequent separation step, a split with predominantly (unconverted) iso-C4 compound (reference symbol i-C4) and a split with predominantly n-C4 compound are again obtained. The latter may, for example, be combined with stream F comprising the n-C4 compound contained in separation unit 39 into stream K, and subjected to a steam cracking procedure 10, such as cracking furnace 13 operating under mild cracking conditions. The iso-C4 compound which does not react in the skeletal isomerization may also be partially or completely recovered to the skeletal isomerization reactor 90 as described in stream L to achieve continuous substantial or complete conversion. However, alternatively after the hydrogenation reaction according to block 44, it may also be used for the cracking of stream H formed therefrom (e.g., under severe cracking conditions of cracking furnace 12).

Figure 6 shows, in schematic flow chart form, a process for the manufacture of hydrocarbons via steam cracking in accordance with another embodiment of the present invention.

Compared to Figure 5, a stream from which the n-C4 compound and the iso-C4 compound have not been separated is removed from the skeletal isomerization reactor 90. It can be at least partially recovered as stream M recovered to the separation unit 39 via the hydroisomerization reactor 60, with the end result that the unconverted iso-C4 compound in the skeletal isomerization reactor 90 is recovered to achieve substantial or complete Conversion. However, if desired, stream N, indicated by the dashed line, may also be cleaved (e.g., under severe cracking conditions of cracking furnace 12) after the hydrogenation reaction according to block 44.

Although not shown herein, it will be understood that additional recycle streams or fresh feed to cracking furnaces 11 through 13 may be provided.

The above figures show partial aspects that can each be used to combine differently from each other.

10‧‧‧Vapor cracking treatment
11, 12, 13‧ ‧ cracking furnace
20‧‧‧ Preparation
30‧‧‧Separation treatment
31, 32, 33, 34, 35, 36, 37, 38, 39‧‧ separate units
41, 42, 43‧‧‧ Hydrotreating
44‧‧‧Hydration process
50‧‧‧Recycling unit
60‧‧‧hydroisomerization reactor
70‧‧‧Additional unit
80‧‧‧ device
90‧‧‧Skele isomerization reactor
A, B, G, I, K, L, M, N‧‧‧
C‧‧‧ Actual cracking gas
C1, C2, C2+, C2-, C3, C3+, C4, C4+, C5+‧‧ ‧ fractions
i-C4‧‧‧iso-C4 compound
n-C4‧‧‧n-C4 compound
D, E, F, H‧‧ ‧ recirculation flow

Figure 1A is a schematic representation of a process diagram for the manufacture of hydrocarbons in accordance with the prior art.

Figure 1B is a schematic representation of a process diagram for the manufacture of hydrocarbons in accordance with the prior art.

Figure 2 is a schematic diagram showing the process for producing hydrocarbons in accordance with an embodiment of the present invention.

Figure 3 is a schematic diagram showing the process for producing hydrocarbons in accordance with an embodiment of the present invention.

Figure 4 is a schematic diagram showing the process for producing hydrocarbons in accordance with an embodiment of the present invention.

Figure 5 is a schematic diagram showing the process for producing hydrocarbons in accordance with an embodiment of the present invention.

Fig. 6 is a schematic process diagram for schematically producing a hydrocarbon according to an embodiment of the present invention.

In the drawings, the corresponding elements are given the same reference numerals and are not repeated for explanation.

10‧‧‧Vapor cracking procedure

11, 12, 13‧ ‧ cracking furnace

20‧‧‧ Preparation procedure

30‧‧‧Separation procedure

34, 39‧‧‧ Separation unit

44‧‧‧Hydrogenation

50‧‧‧Recycling unit

60‧‧‧hydroisomerization reactor

A, B, G, I‧‧‧ streams

C‧‧‧Cleavage gas

C4, C4+, C5+‧‧ ‧ fractions

i-C4‧‧‧iso-C4 compound

n-C4‧‧‧n-C4 compound

F, H‧‧ ‧ recycling stream

Claims (14)

A method for producing a hydrocarbon product, comprising: a) providing a C4 hydrocarbon stream (C4) comprising at least 80% of branched hydrocarbons and four linear hydrocarbons each having four carbon atoms; b) Recovering from the C4 hydrocarbon stream (C4) or a stream derived therefrom a n-C4 split (n-C4) comprising at least 80% of a linear hydrocarbon having four carbon atoms, and comprising four One of the branched hydrocarbons of a carbon atom is iso-C4 split (i-C4); and c) the n-butane contained therein is converted to a degree of cracking of at least 50% and not more than 92% for vapor cracking at least a portion of The n-C4 split (n-C4) or a stream derived therefrom. The method of claim 1, wherein: - at least some of the branched hydrocarbons contained in the iso-C4 split (i-C4) are reacted by skeletal isomerization to form a linear hydrocarbon. The method of claim 1 or 2, wherein: - by recovering the n-C4 split and the iso-C4 split (n-C4, i-C4) according to b), by hydrogenation Isomerization to react at least some of the 1-butene contained in the C4 hydrocarbon stream (C4) to form 2-butene. The method of any of the preceding claims, wherein: - the isobutane contained therein is converted to a degree of cracking of greater than 91% to vapor cleave at least some of the iso-C4 split (iso-C4) Or a stream derived from it. The method of any of the preceding claims, wherein during the steam cracking according to c), the degree of cracking used is less than 90%, 88%, 86%, 84%, 82%, 80%, 78%, 76%, 74%, 72%, 70% or 65% and more than 50% or 60% n-butane conversion. The method of any of the preceding claims, wherein the iso-C4 split (i-C4) or a stream derived therefrom (i-C4) is at least partially subjected to a hydrogenation process. The method of any of the preceding claims, wherein the C4 hydrocarbon stream (C4) provided according to a) is at least partially from at least one cracked gas obtained by steam cracking according to c) ( C) Manufacturing. The method of any of the preceding claims, wherein the C4 hydrocarbon stream (C4) provided according to a) is at least partially from a cracked gas formed by steam cracking of the fresh feed (A). (C) Manufacture, in particular a petroleum gas composition and/or a petroleum gas condensate from one or more petroleum fractions having two to four carbon atoms. A method according to any one of the preceding claims, wherein the C4 hydrocarbon stream (C4) provided according to a) is formed at least in part from a fresh feed (A) which has not been subjected to a steam cracking treatment in advance, in particular It is at least one product from one or more petroleum fractions, a petroleum gas composition having two to four carbon atoms, and/or a petroleum gas condensate and/or a refining procedure. A method according to any one of the preceding claims, wherein the steam cracking is carried out using a steam amount of 0.4 kg/kg, in particular 0.2 to 0.7 kg/kg. A method according to any one of the preceding claims, wherein the steam cracking is effected in at least one steam furnace (11, 12, 13), wherein at least one other furnace feed in the form of at least one recovered stream is provided ( A) and / or at least one fresh feed. The method of any of the preceding claims, wherein the C4 hydrocarbon stream is before the n-C4 split according to b) and the iso-C4 split (i-C4, n-C4) recovery (C4) Separation of 1,3-butadiene (BD). The method of claim 12, wherein after separating the 1,3-butadiene (BD), the isobutylene contained in the C4 hydrocarbon stream (C4) is at least partially reacted to form a t-butyl group. The ether, and tert-butyl ether, is also separated from the C4 hydrocarbon stream (C4). A process according to any one of the preceding claims, wherein at least one other stream, in particular a stream comprising butyne and/or a hydrocarbon having five carbon atoms, is fed to the C4 hydrocarbon Flow (C4).