Steam Cracking Process Incorporating Oxidized Disulfide Oil Additives

Abstract

An oxidized disulfide oil (ODSO) component or an ODSO and a disulfide oil (DSO) component are added to the steam cracker feed. During pyrolysis, the ODSO or ODSO and DSO components in the steam cracker mixture minimize the formation of coke on the steam cracker coils.

Description

[Technical field]

[0001] The present disclosure relates to blending oxidized disulfide oil compounds or mixtures of disulfide oils and oxidized disulfide oils with steam cracker feed to minimize coke formation. [Background technology]

[0002] Steam cracking Steam cracking of gaseous hydrocarbons such as ethane, propane and butane, and liquid hydrocarbons such as light C5-C6 naphtha is the lead technology for the production of ethylene. In the steam cracking process, the feed is diluted with steam and delivered to a steam cracker. The cracker is the heart of the process. Steam cracking is a complex process followed by cooling, compression and separation steps.

[0003] Coking is an undesirable side reaction from steam cracking. Coking is a major operational problem in steam cracking furnaces and the radiant section of heat transfer line exchangers. Steam dilution lowers the hydrocarbon partial pressure of the cracked compounds, thus promoting the formation of primary reaction products. Steam also reduces the tendency for coke to deposit on the furnace tubes.

[0004] Coke is an unavoidable by-product of pyrolysis, although it is not a desired product. It is well known that surface catalytic reactions result in the formation of coke. In many cases, the formation of coke is caused by nickel and iron on the alloy surface. Coke formation causes increased pressure drop, impaired heat transfer, increased fuel consumption, and thus high production losses. As the coke formation increases, the outer tube surface temperature increases continuously. This affects the selectivity of the process and also causes more rapid coke formation. The formed coke can be removed by controlled burning with steam and air. During this coke removal process, the steam cracking furnace is in a non-productive downtime state. Furthermore, the decoking cycle leads to a shortened life of the coils in the steam cracking furnace.

[0005] MEROX Process The mercaptan oxidation process, commonly referred to as the MEROX process, has long been used to remove the commonly odorous mercaptans found in many hydrocarbon streams and was introduced into the refining industry more than 50 years ago. Due to regulatory requirements to reduce the sulfur content of fuels for environmental reasons, refineries have been and continue to be faced with the disposal of large amounts of sulfur-containing by-products.

[0006] Disulfide oil (DSO) compounds are produced as a by-product of the MEROX process in which mercaptans are removed from any of a variety of petroleum streams, including liquefied petroleum gas, naphtha, and other hydrocarbon fractions. This is commonly referred to as a "sweetening process" because it removes rancid or malodorous mercaptans present in crude oil. The term "DSO" is used for convenience in this specification and claims and is understood to include the mixture of disulfide oils produced as a by-product of the mercaptan oxidation process.

[0007] As noted above, the name "MEROX" derives from the function of the process itself, namely, the conversion of mercaptans by oxidation. The MEROX process in all of its applications is based on the ability of an organometallic catalyst in a basic environment, such as a caustic environment, to accelerate the oxidation of mercaptans to disulfides at near ambient temperature and pressure. The overall reaction can be represented as follows:

number

[0008] (where R is a hydrocarbon chain that may be linear, branched, or cyclic, and the chain may be saturated or unsaturated) In most petroleum fractions, a mixture of mercaptans exists such that R may have 1, 2, 3, up to 10, or more carbon atoms in the chain. This variable chain length is represented in the reaction by R and R'. The reaction is then written as follows:

number

[0009] This reaction occurs spontaneously whenever any rancid mercaptan-containing distillate is exposed to atmospheric oxygen, but it proceeds at a very slow rate. Moreover, the catalytic reaction (1) above requires the presence of an alkaline caustic solution, such as aqueous sodium hydroxide. Mercaptan oxidation proceeds at economically practical rates at moderate refinery downstream temperatures.

[0010] The MEROX process can be run on both liquid streams and combined gaseous and liquid streams. In the case of liquid streams, the mercaptans are converted directly to disulfides which remain in the product, thus not reducing the overall sulfur content of the effluent stream.

[0011] The MEROX process typically utilizes a fixed bed reactor system for the liquid stream and is usually used with an input feedstock having an end point greater than 135°C to 150°C. Mercaptans are converted to disulfides over a catalyst in the fixed bed reactor system, for example, over activated carbon impregnated with the MEROX reagent and wetted with caustic solution. Air is injected into the hydrocarbon feed stream prior to the reactor and mercaptans in the feed are oxidized to disulfides during passage through the catalyst impregnated bed. The disulfides are substantially insoluble in caustic solution and remain in the hydrocarbon phase. Post-treatment is required to remove undesirable by-products resulting from known side reactions, such as neutralization of H2S, oxidation of phenolic compounds, entrained caustic solution, etc.

[0012] The vapor pressure of disulfides is relatively low compared to that of mercaptans so their presence is less objectionable from an odor standpoint, but their sulfur content makes them environmentally unacceptable and their disposal can be difficult.

[0013] In the case of mixed gas and liquid streams, extraction is applied to both phases of the hydrocarbon stream. The degree of completeness of mercaptan extraction depends on the solubility of the mercaptans in the alkaline solution, which is a function of the molecular weight of the individual mercaptans, the degree of branching of the mercaptan molecule, the concentration of caustic soda, and the temperature of the system. The resulting DSO compounds are then separated and the caustic solution is regenerated by oxidation with air in the presence of a catalyst for reuse.

[0014] Referring to the accompanying drawings, FIG. 1 is a simplified diagram of a generalized conventional prior art MEROX process using liquid-liquid extraction to remove sulfur compounds in an embodiment in which a complex hydrocarbon stream of propane and butane containing mercaptans (1) is treated, i.e., a MEROX unit (1010), which comprises the steps of introducing the hydrocarbon stream (1) having a homogeneous catalyst into an extraction vessel (10) containing a caustic solution (2), in some embodiments the catalyst being a homogeneous cobalt-based catalyst; passing the hydrocarbon catalyst stream countercurrently through an extraction section of an extraction (10) vessel, the extraction section including one or more liquid-liquid contacting extraction decks or trays (not shown) for catalytic reaction with the circulating caustic solution to convert mercaptans to water-soluble alkali metal alkanethiolate compounds; withdrawing a mercaptan-free, or substantially mercaptan-free, hydrocarbon product stream (3) from the extraction vessel (10); recovering a combined spent caustic solution and alkali metal alkanethiolate stream (4) from the extraction vessel (10); subjecting the spent caustic solution to catalytic wet air oxidation in a reactor (20) into which a catalyst (5) and air (6) are introduced to provide a regenerated spent caustic solution (8) and to convert the alkali metal alkanethiolate compounds to disulfide oil; recovering a by-product stream (7) of DSO compounds and small proportions of other sulfides, e.g., monosulfides and trisulfides; Includes.

[0015] The effluent of the wet air oxidation step in the MEROX process preferably contains a low percentage of sulfides and a high percentage of disulfide oil. As known to those skilled in the art, the composition of this effluent stream depends on the effectiveness of the MEROX process, with the sulfides being presumed to be a carryover material. Various catalysts have been developed for commercial implementation of the process. The efficiency of the MEROX process is also a function of the amount of H2S present in the stream. It is common refinery practice to provide a pre-wash step for H2S removal.

[0016] The disulfide oil compounds produced in the MEROX process may contain a variety of disulfides. For example, a MEROX unit designed for the recovery of propane and butane will produce a disulfide oil mixture having the composition set forth in Table 1.

[0017] [Table 1]

[0018] Table 1 shows the composition of the disulfide oil from the semi-quantitative GC-MS data. No standards were measured for the components, but the data in Table 1 are accurate enough to indicate relative amounts. The quantitative total sulfur content was determined by energy dispersive X-ray fluorescence spectroscopy, which indicated 63 wt% sulfur, a value that will be used in subsequent calculations. Although the GC-MS results show evidence of trace amounts of tri-sulfide species, the majority of the disulfide oil stream contains the three components identified in Table 1.

[0019] The by-product disulfide oil produced by the MEROX unit can be processed and / or disposed of in various other refinery unit operations. For example, DSO can be added to a fuel oil pool at the expense of a higher sulfur content in the resulting pool. DSO can be processed in a hydrotreating / hydrocracking unit at the expense of higher hydrogen consumption. Disulfide oil also has an unpleasant odor or rancidity that, although less common, is problematic in handling the oil due to its relatively low vapor pressure at ambient temperatures.

[0020] The enhanced MEROX process ("E-MEROX") is a modified MEROX process that adds an additional step in which the DSO compounds are oxidized with an oxidizing agent in the presence of a catalyst to produce a mixture of oxidized disulfide oil (ODSO) compounds. The by-product DSO compounds from the mercaptan oxidation process can be oxidized, preferably in the presence of a catalyst, to constitute a rich source of ODSO compounds which are sulfoxides, sulfonates, sulfinates, sulfones and their corresponding disulfur mixtures.

[0021] The oxidizing agent may be a liquid peroxide selected from the group consisting of alkyl hydroperoxides, aryl hydroperoxides, dialkyl peroxides, diaryl peroxides, peresters, and hydrogen peroxide. The oxidizing agent may also be a gas, including air, oxygen, ozone, and oxides of nitrogen. The catalyst is preferably a homogeneous water-soluble compound that is a transition metal, including active species selected from the group consisting of Mo(VI), W(VI), V(V), Ti(IV), and combinations thereof.

[0022] The ODSO compounds produced in the E-MEROX process generally contain two phases, an aqueous phase and an aqueous insoluble phase. The E-MEROX process can be adjusted depending on the desired ratio of aqueous and insoluble compounds present in the product ODSO mixture. Partial oxidation of the DSO compounds increases the relative amount of aqueous insoluble ODSO compounds present in the ODSO product, and most or almost complete oxidation of the DSO compounds increases the relative amount of aqueous ODSO compounds present in the ODSO product. Details of ODSO compositions are described in USP 10,781,168, which is incorporated herein by reference.

[0023] Table 2 contains examples of ODSO compounds produced by oxidation of DSO by-product compounds produced in the MEROX sulfur reduction or sweetening process of hydrocarbons including mercaptans, where R and R' are alkyl groups containing 1 to 10 carbon atoms.

[0024] [Table 2-1] [Table 2-2]

[0025] Figure 2 is a simplified schematic of a generalized conventional E-MEROX process including an E-MEROX unit (1030). The MEROX unit (1010) operates similarly to Figure 1, and like reference numbers represent like units / feeds.

[0026] In Figure 2, the effluent stream (7) from the generalized MEROX unit of Figure 1 is processed. It is understood that the processing of the combined propane and butane stream of Figure 1 is exemplary only, and that separate streams of products, and combined or separate streams of other mixed longer chain products, may be subjected to a process for recovering and oxidizing DSO to produce ODSO compounds, i.e., the E-MEROX process.

[0027] To carry out the E-MEROX process, it is necessary to add equipment for recovering the by-product DSO compounds from the MEROX process and provide (a) a suitable reactor (30) in which the DSO compounds are introduced in the presence of a catalyst (32) and an oxidizing agent (34) and which subjects the DSO compounds to a catalytic oxidation step to produce a mixed stream (36) of water and ODSO compounds, and (b) a conventional separation vessel (40) for separating the by-products (44) from the ODSO compounds (42). The by-products (44) typically comprise wastewater when hydrogen peroxide is used as the oxidizing agent. Alternatively, when other organic peroxides are used as the oxidizing agent, the by-products (44) typically comprise the alcohol of the peroxide used. For example, when butyl peroxide is used as the oxidizing agent, the by-product alcohol (44) will be butanol.

[0028] After the water-soluble ODSO compounds are separated from the wastewater fraction, they are sent to a fractionation zone (not shown) for recovery. The fractionation zone may include a distillation unit. In certain embodiments, the distillation unit may be a flash distillation unit with no theoretical plates to obtain distillation cuts with greater overlap with each other, or in other embodiments, the distillation unit may be a flash distillation unit with at least 15 theoretical plates to have effective separation between the cuts. In certain embodiments, the distillation unit may operate at ambient pressure and at temperatures ranging from 100° C. to 225° C. In other embodiments, the fractionation may be carried out continuously under vacuum conditions. In these embodiments, the fractionation is carried out at the respective boiling points under reduced pressure, e.g., at 350 mbar and 10 mbar, with temperatures ranging from 80° C. to 194° C. and 11° C. to 98° C., respectively. After fractionation, the wastewater is sent to a wastewater pool (not shown) for conventional treatment before disposal. The wastewater by-product fraction may contain small amounts of water-insoluble ODSO compounds, e.g., in the range of 1 ppmw to 10,000 ppmw. The wastewater by-product fraction may contain small amounts of water soluble ODSO compounds, for example in the range of 100 ppmw to 50,000 ppmw. In embodiments where alcohol is the by-product alcohol, the alcohol may be recovered and sold commercially or added to fuels such as gasoline. The alcohol by-product fraction may contain small amounts of water insoluble ODSO compounds, for example in the range of 1 ppmw to 10,000 ppmw. The alcohol by-product fraction may contain small amounts of water soluble ODSO compounds, for example in the range of 100 ppmw to 50,000 ppmw.

[0029] As described in US 2020 / 0181517, ODSO compounds have been found to be useful as lubricity additives for diesel fuels and more economical than additives currently available for that purpose, and have also been found to be useful as solvents for aromatic solvent extraction processes, as described in USP 10,793,782, both of which are incorporated herein by reference. When refiners have produced or have on hand amounts of DSO compounds that exceed their foreseeable needs for these or other uses, they may wish to dispose of the DSO compounds in order to empty storage tanks and / or remove product from inventory to reduce refinery waste. [Prior art documents] [Patent documents]

[0030] [Patent Document 1] USP 10,781,168 [Patent Document 2] US 2020 / 0181517 [Patent Document 3] USP 10,793,782 Summary of the Invention [Problem to be solved by the invention]

[0031] Thus, there is a clear and long-felt need to provide an efficient and economical process for treating the large quantities of DSO by-products and their derivatives, to affect and improve their properties to facilitate and simplify their environmentally acceptable disposal and / or to enable utilization of the reformed products in refineries, thereby increasing the value of this class of by-products to refiners. [Means for solving the problem]

[0032] The above needs are met and other advantages are provided by the process of the present invention which economically uses relatively low value oxidized disulfide oils or blends of oxidized disulfide oils and disulfide oils as additives in the steam cracking process. The additives can also improve steam cracking operations by minimizing coke formation in the steam cracker tubes and protect the metallurgy of the steam cracker unit. In certain embodiments, the integrated MEROX, E-MEROX and steam cracker process also provides improved refinery efficiency by providing additional outlets for ODSO compounds and ODSO / DSO mixtures.

[0033] In one embodiment, the present disclosure provides: introducing said oxidized disulfide oil (ODSO) stream and said steam cracker feed stream into a steam cracking complex; mixing said ODSO stream and said steam cracker feed stream within said steam cracking complex to produce an internal steam cracker mixture comprising an ODSO component; subjecting the internal steam cracker mixture to thermal cracking in the steam cracker complex to produce a steam cracker product; A steam cracking process comprising: During the pyrolysis, the ODSO component in the internal steam cracker mixture is directed to a method that minimizes coke formation on the steam cracker coils.

[0034] In another embodiment, the present disclosure provides: combining an oxidized disulfide oil (ODSO) stream with a steam cracker feed stream to produce an improved steam cracker feed comprising an ODSO component; introducing said improved steam cracker feed into a steam cracking complex; subjecting said advanced steam cracker feed to thermal cracking in said steam cracking complex to produce a steam cracker product; A steam cracking process comprising: During the pyrolysis, the ODSO component in the advanced steam cracker feed is directed towards a process that minimizes coke formation on the steam cracker coils.

[0035] Further aspects, embodiments, and advantages of these exemplary aspects and embodiments are described in detail below. It should be further understood that both the preceding information and the following detailed description are merely exemplary examples of the various aspects and embodiments, and are intended to provide an overview or framework for understanding the nature and features of the claimed aspects and embodiments. The accompanying drawings are included to explain and facilitate a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification. The drawings, together with the remainder of the specification, serve to explain the principles and operation of the described and claimed aspects and embodiments.

[0036] The method of the present disclosure will now be described in more detail with reference to the accompanying drawings, in which like numbers are used to refer to the same or similar elements. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a simplified schematic of a generalized prior art mercaptan oxidation or MEROX process for liquid-liquid extraction of combined propane and butane streams. [Diagram 2] FIG. 1 is a simplified schematic of a generalized prior art improved mercaptan oxidation or E-MEROX process. [Diagram 3] FIG. 1 is a simplified diagram of an embodiment of the present disclosure. [Figure 4] FIG. 1 is a simplified diagram of an embodiment of the present disclosure. [Diagram 5] 1 is a simplified diagram of an embodiment of an integrated process of the present disclosure. [Figure 6] 1 is a simplified diagram of an embodiment of an integrated process of the present disclosure. [Figure 7] FIG. 1 is a simplified schematic of a steam cracking complex of an embodiment of an integrated process of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Disclosed herein is a process and system for economically using relatively low value oxidized disulfide oil or a blend of oxidized disulfide oil and disulfide oil as an additive in a steam cracking process to inhibit coke formation in the steam cracking tubes and protect the metallurgy of the steam cracker unit.

[0039] In the following description, the terms "disulfide oil", "DSO", "DSO mixture" and "DSO compound" may be used interchangeably for convenience.

[0040] In the following description, the terms "oxidized disulfide oil", "derivatives of disulfide oil", "ODSO", "ODSO mixture" and "ODSO compound" may be used interchangeably for convenience.

[0041] In the following description, the terms "DSO / ODSO", "DSO / ODSO mixture" and "DSO / ODSO compound" may be used interchangeably for convenience.

[0042] The phrase "major portion" with respect to a particular stream or streams means at least about 50% by weight and up to 100% by weight, or the same value in another specified unit.

[0043] The term "majority" with respect to a particular stream or streams means at least about 75% by weight and up to 100% by weight, or the same value in another specified unit.

[0044] The phrase "substantial portion" means at least about 90, 95, 98, or 99% by weight and up to 100% by weight, or the same value in another specified unit.

[0045] The phrase "minor portion" with respect to a particular stream or streams means from about 1, 2, 4 or 10% by weight up to about 20, 30, 40 or 50% by weight, or the same value in another specified unit.

[0046] As used herein, all boiling points are relative to the hydrocarbon fraction obtained from crude oil via atmosphere and / or refer to true boiling point values ​​obtained from crude oil assays, or commercially accepted equivalents.

[0047] The term "naphtha" as used herein refers to a hydrocarbon boiling in the range of about 20-205, 20-193, 20-190, 20-180, 20-170, 32-205, 32-193, 32-190, 32-180, 32-170, 36-205, 36-193, 36-190, 36-180, or 36-170°C.

[0048] In certain embodiments, naphtha, light naphtha and / or heavy naphtha refer to petroleum fractions obtained by crude oil distillation or by distillation of intermediate refinery processes as described herein.

[0049] The modifier "straight run" is used herein with its well-known meaning, i.e., to refer to a fraction obtained directly from an atmospheric distillation unit, optionally subjected to steam stripping, without other refining processes such as hydrotreating, fluid catalytic cracking, or steam cracking. Examples of this include "straight run naphtha" and its acronym "SRN," which, as is well known, refers to "naphtha," as defined above, obtained directly from an atmospheric distillation unit, optionally subjected to steam stripping.

[0050] The term "atmospheric gas oil" and its acronym "AGO" as used herein refer to hydrocarbons boiling in the range of about 205-400, 205-380, 205-370, 205-360, 205-340, 205-320, 240-400, 240-380, 240-370, 240-360, 240-340, 240-320, 270-400, 270-380, 270-370, 270-360, 270-340, or 270-320°C.

[0051] The term "vacuum gas oil" and its acronym "VGO" as used herein refers to a hydrocarbon boiling in the range of about 370-550, 370-540, 370-530, 370-510, 400-550, 400-540, 400-530, 400-510, 420-550, 420-540, 420-530 or 420-510°C.

[0052] The term "fuel" refers to products derived from crude oil that are used as energy carriers. Fuels commonly produced in refineries include, but are not limited to, gasoline, jet fuel, diesel fuel, fuel oil, and petroleum coke. Unlike petrochemicals, which are collections of well-defined compounds, fuels are usually complex mixtures of various hydrocarbon compounds.

[0053] The terms "aromatic hydrocarbon" or "aromatic (aromatic compound)" are very well known in the art. Thus, the term "aromatic hydrocarbon" refers to cyclic conjugated hydrocarbons that have significantly greater stability (due to delocalization) than that of a hypothetical localized structure (e.g., the Kekulé structure). The most common method of measuring the aromaticity of a given hydrocarbon is to determine its 1 Diatropicity in H NMR spectra, for example the presence of chemical shifts in the range of 7.2-7.3 ppm for benzene ring protons, is observed.

[0054] The term "C# hydrocarbons" or "C#" is used herein with its familiar meaning to refer to hydrocarbons having that number of carbon atoms, where "#" is an integer value. The term "C#+ hydrocarbons" or "C#+" refers to hydrocarbons having the number of carbon atoms or more. The term "C#- hydrocarbons" or "C#-" refers to hydrocarbons having the number of carbon atoms or less. Ranges are similarly described, for example, C1-C3 refers to a mixture containing C1, C2, and C3.

[0055] The term "petrochemicals" or "petrochemicals" refers to chemical products derived from crude oil that is not used as fuel. Petrochemicals include olefins and aromatics that are used as base feedstocks to make chemicals and polymers. Typical olefinic petrochemicals include, but are not limited to, ethylene, propylene, butadiene, butylene-1, isobutylene, isoprene, cyclopentadiene, and styrene. Typical aromatic petrochemicals include, but are not limited to, benzene, toluene, xylene, and ethylbenzene.

[0056] The term "olefin" is used herein in its familiar sense, i.e., an unsaturated hydrocarbon compound containing at least one carbon-carbon double bond. In the plural, the term "olefins" refers to a mixture containing two or more unsaturated hydrocarbon compounds containing at least one carbon-carbon double bond. In certain embodiments, the term "olefins" refers to a mixture containing two or more of ethylene, propylene, butadiene, butylene-1, isobutylene, isoprene, and cyclopentadiene.

[0057] The phrase "major portion" with respect to a particular stream or streams means at least about 50% by weight and up to 100% by weight, or the same value in another specified unit.

[0058] The term "majority" with respect to a particular stream or streams means at least about 75% by weight and up to 100% by weight, or the same value in another specified unit.

[0059] The phrase "substantial portion" with respect to a particular stream or streams means at least about 90, 95, 98, or 99% by weight and up to 100% by weight, or the same value in another specified unit.

[0060] The phrase "minor portion" with respect to a particular stream or streams means from about 1, 2, 4 or 10% by weight up to about 20, 30, 40 or 50% by weight, or the same value in another specified unit.

[0061] Referring to FIG. 3, in one embodiment of a process and system, the ODSO stream (1042) and the steam cracker feed (1202) are combined and sent to a steam cracking zone (1220) in a steam cracking complex (1215) along with a steam source (1223).

[0062] In certain embodiments, the ODSO stream (1042) comprises a mixture from the oxidation of DSO compounds, the mixture comprising dialkyl-thiosulfoxides (R-SO-S-R'), dialkyl-thiosulfones (R-SOO-S-R'), dialkyl-sulfone sulfoxides (R-SOO-SO-R'), dialkyl-disulfones (R-SOO-SOO-R'), dialkyl-disulfoxides (R-SO-SO-R'), alkyl-sulfoxide sulfonates (R-SO-SOO-OH), alkyl-sulfone sulfonates (R-SOO-SOO-OH), alkyl-sulfoxide sulfinates (R-SO-SO-OH), and alkyl-sulfonesulfinates (R-SOO-SO-OH). In certain embodiments, the ODSO stream (1042) comprises, consists of, or consists essentially of at least one ODSO compound selected from the group consisting of compounds having the general formula: (R-SO-S-R'), (R-SOO-S-R'), (R-SOO-SO-R'), (R-SOO-SOO-R'), (R-SO-SO-R'), (R-SO-SOO-OH), (R-SOO-SOO-OH), (R-SO-SO-OH), (R-SOO-SO-OH), (X-SO-OR) and (X-SOO-OR). In certain embodiments, the ODSO stream (1042) comprises, consists of, or consists essentially of a mixture of two or more ODSO compounds selected from the group consisting of compounds having the general formula: (R-SO-S-R'), (R-SOO-S-R'), (R-SOO-SO-R'), (R-SOO-SOO-R'), (R-SO-SO-R'), (R-SO-SOO-OH), (R-SOO-SOO-OH), (R-SO-SO-OH), (R-SOO-SO-OH), (X-SO-OR) and (X-SOO-OR). In certain embodiments, the ODSO stream (1042) comprises, consists of, or consists essentially of at least one water soluble ODSO compound selected from the group consisting of compounds having the general formula (R-SOO-SO-R'), (R-SOO-SOO-R'), (R-SO-SOO-OH), (R-SOO-SOO-OH), (R-SOO-SO-OH), (X-SO-OR) and (X-SOO-OR).In certain embodiments, ODSO stream (1042) comprises, consists of, or consists essentially of a mixture of two or more water soluble ODSO compounds selected from the group consisting of compounds having the general formula (R-SOO-SO-R'), (R-SOO-SOO-R'), (R-SO-SOO-OH), (R-SOO-SOO-OH), (R-SOO-SO-OH), (X-SO-OR) and (X-SOO-OR). In certain embodiments, ODSO stream (1042) comprises, consists of, or consists essentially of an ODSO compound selected from the group consisting of (R-SOO-SO-R'), (R-SOO-SOO-R'), (R-SO-SOO-OH), (R-SOO-SOO-OH), (R-SO-SO-OH), (R-SOO-SO-OH) and mixtures thereof. Since the source of DSO is a refinery feed stream, it can be understood that the R and X substituents are diverse, e.g., methyl and ethyl subgroups, and the number of sulfur atoms, S, in the as-received feed stream can be extended to 3, e.g., trisulfide compounds. In certain embodiments, in the above formula, R and R' are alkyl or aryl groups containing 1 to 10 carbon atoms. Further, X represents an ester, (R-SO) or (R-SOO), where R is as defined above.

[0063] In certain embodiments, the DSO stream (1024) may be mixed with an ODSO stream (1042) to produce a combined DSO / ODSO stream (1046), which is then mixed with the steam cracker feed (1202). In certain embodiments, the mixing may be accomplished by mixing techniques known in the art, such as a separate mixing tank setup equipped with a stirrer, injectors, and / or in-line mixers (not shown).

[0064] The ratio of ODSO to DSO in stream (1046) can range from 100:0 to 0.001:99.999. In certain embodiments, a substantial portion of the DSO / ODSO stream (1046) comprises DSO compounds and a minor portion of the DSO / ODSO stream (1046) comprises DSO compounds, e.g., the ratio of ODSO to DSO in stream (1046) can range from 100:0 to 99:1, or 100:0 to 95:5, or 100:0 to 90:10 V%. In certain embodiments, a majority of the DSO / ODSO stream (1046) comprises ODSO compounds and a minor portion of the DSO / ODSO stream (1046) comprises DSO compounds, e.g., the ratio of ODSO to DSO in stream (1046) can range from 100:0 to 80:20, or 100:0 to 75:25 V%. In certain embodiments, a major portion of the DSO / ODSO stream (1046) comprises ODSO compounds and a minor portion of the DSO / ODSO stream (1046) comprises DSO compounds, for example, the ratio of ODSO to DSO in stream (1046) can range from 100:0 to 60:40 or 100:0 to 50:50 V%.

[0065] In certain embodiments, there is no DSO stream mixed with the ODSO stream (1042), and therefore the ratio of ODSO to DSO in stream (1046) is 100:0 V%.

[0066] The steam cracker feed (1202) is mixed with the ODSO stream (1042) (or DSO / ODSO stream (1046)) to form an improved steam cracker feed (1222), which is sent along with a steam source (1223) to one or more inlets of the steam cracking zone (1220). In certain embodiments, the ODSO stream (1042) (or the DSO / ODSO stream (1046)) is injected into a steam cracker feed pipe containing the steam cracker feed (1202). In certain embodiments, turbulent flow in the pipe allows the streams to mix well before entering the steam cracker pipe.

[0067] In certain embodiments, the steam cracking complex (1215) includes a steam cracking zone (1220) and other additional downstream processing units, which are described in more detail below.

[0068] In each embodiment, the steam cracking zone (1220) within the steam cracking complex (1215) operates as a large- or small-scale thermal cracking process and generally converts the steam cracker feed (1222) into steam cracker products resulting from the steam cracking complex (1215), which generally include a mixed gas product stream (1225) including mixed C1-C4 paraffins and olefins, pyrolysis gasoline (1226), and pyrolysis fuel oil (1228).

[0069] Depending on the particular configuration of the steam cracker complex (1215) (described in more detail below with reference to FIG. 7), the steam cracker product (1225) generally comprises hydrogen (1232), fuel gas (1234), ethylene (1236), propane (1246), propylene (1248), 1,3-butadiene product (1252), methyl tertiary butyl ether (1262), and a 1-butene product stream (1268). In some embodiments, the hydrogen (1232), fuel gas (1234), ethylene (1236), propane (1246), propylene (1248), 1,3-butadiene product (1252), methyl tertiary butyl ether (1262), and 1-butene product stream (1268) streams are referred to as the mixed product stream (1225).

[0070] The ODSO or combination of DSO / ODSO components in the improved steam cracker feed (1222) helps minimize or inhibit coke formation on the cracker coils and also protects the metallurgy of the steam cracker.

[0071] Examples of the steam cracker feed (1202) include one or more light hydrocarbons such as ethane, propane, butane; light naphtha paraffinic hydrocarbons containing 5-6 carbon atoms; heavy naphtha hydrocarbons including paraffins; naphthenes; aromatics having carbon numbers in the range of 7-12; middle distillate hydrocarbons including paraffins; naphthenes and aromatics having boiling points in the range of 180-370° C., straight run or hydrotreated vacuum gas oils having boiling points in the range of 370 to 565° C. In one or more specific embodiments, the steam cracker feed (1202) may include diesel fuel, and more specifically, ultra-low sulfur diesel fuel, in selected embodiments having less than 10 ppm sulfur.

[0072] In some embodiments, preferred steam cracker feeds include one or more low sulfur oil-containing feeds, such as light hydrocarbons, such as ethane, propane, butane; light naphtha paraffinic hydrocarbons containing 5-6 carbon atoms.

[0073] In some embodiments, DSO may be added to the convection section of a steam cracking furnace and ODSO may be added to the pyrolysis section.

[0074] In another embodiment of the present process and system, with reference to FIG. 4, the ODSO stream (1042), the steam cracker feed (1202), and a steam source (1223) are delivered to a steam cracking zone (1220) within a steam cracking complex (1215).

[0075] The embodiment shown in FIG. 4 operates similarly to the embodiment shown in FIG. 3, with like reference numbers representing like units / feeds. In certain embodiments, it may be preferred to send the ODSO compounds and the steam cracker feed to the steam cracker through separate inlets. For example, depending on the exact composition and amount of ODSO compounds present in the ODSO stream (1042) (or DSO / ODSO stream (1046)), the ODSO compounds may be partially or completely immiscible with the steam cracker feed (1202). For example, ODSO compounds with two oxygen atoms are oil soluble and miscible in the steam cracker feed. On the other hand, ODSO compounds with three or more oxygen atoms are water soluble and generally immiscible in the steam cracker feed. In some embodiments, ODSO compounds with three or more oxygen atoms at ppm levels may be miscible with the steam cracker feed.

[0076] The steam cracker feed (1202) and the ODSO stream (1042) (or DSO / ODSO stream (1046)), along with a steam source (1223), are passed through separate inlets to the steam cracking zone (1220) of the steam cracking complex (1215). In this embodiment, the steam cracker feed (1202) and the ODSO stream (1042) (or DSO / ODSO stream (1046)) are internally mixed within the steam cracking zone (1220) prior to thermal cracking.

[0077] In a similar manner as described with reference to FIG. 3, all or a portion of the DSO stream (1024) may be mixed with the ODSO stream (1042) to produce a combined DSO / ODSO stream (1046), which is then sent to one or more inlets of the steam cracking zone (1220).

[0078] The ODSO and / or combined DSO / ODSO components present in the steam cracking zone (1220) help minimize or inhibit coke formation on the cracker coils and also protect the metallurgy of the steam cracker.

[0079] In certain embodiments, the amount of ODSO stream (1042) or combined DSO / ODSO stream (1046) that may be added to the steam cracker feed (1202) may range from 10 to 1000 ppmw, 10 to 500 ppmw, 10 to 300 ppmw, or 10 to 100 ppmw. The amount of ODSO or ODSO / DSO compounds added to the steam cracker feed is independent of whether the ODSO compounds are added to the steam cracker feed prior to introduction to the steam cracker or whether the ODSO compounds are added directly into the steam cracker.

[0080] ODSO compounds are used to reduce coke formation in steam cracking furnaces as described with reference to Figures 3 and 4. In certain embodiments, direct integration with an E-MEROX unit, direct integration with a MEROX unit, or direct integration with an E-MEROX unit and a MEROX unit are possible.

[0081] An embodiment of the disclosed process for treating by-product oxidized disulfide oil in an integrated process including both a MEROX unit and an E-MEROX unit is described with reference to Figures 5 and 6. An embodiment in which the E-MEROX unit or one of the MEROX units is integrated is not shown but can be similarly implemented. For example, an ODSO stream can be brought in and combined with a DSO stream from an integrated MEROX unit, or a DSO stream can be brought in and combined with an ODSO stream from an integrated E-MEROX unit.

[0082] Referring to Figure 5, one embodiment of the present process and system includes a MEROX unit (1010), an improved MEROX (E-MEROX) unit (1030), and a steam cracking complex (1215). The MEROX unit (1010) and the improved MEROX (E-MEROX) unit (1030) operate similarly to those in Figures 1-2, and like reference numbers represent like units / feeds. All or a portion of the by-product stream of DSO compounds (1007) from the MEROX unit (1010) is sent to the E-MEROX unit (1030) via stream (1022) for conversion to an ODSO stream (1042).

[0083] In certain embodiments, stream (1024), which is a portion of the DSO stream (1007), is mixed with an ODSO stream (1042) to produce a combined DSO / ODSO stream (1046), which is then mixed with the steam cracker feed (1202).

[0084] The steam cracker feed (1202) is mixed with an ODSO stream (1042) (or a DSO / ODSO stream (1046)) to form an improved steam cracker feed (1222), which is sent to the steam cracker complex (1215) along with a steam source (1223). In certain embodiments, mixing may be accomplished by mixing techniques known in the art, such as a separate mixing vessel system equipped with a stirrer, injectors, and / or in-line mixers. In certain embodiments, the ODSO stream (1042) (or the DSO / ODSO stream (1046)) is injected into the steam cracker feed pipe containing the steam cracker feed (1202). In certain embodiments, turbulent flow in the pipe allows the streams to mix well.

[0085] The ODSO component or combination of DSO / ODSO components in the improved steam cracker feed (1222) helps minimize or inhibit coke formation on the cracker coils and also protects the metallurgy of the steam cracker.

[0086] Referring to Figure 6, another embodiment of the present process and system includes a MEROX unit (1010), an advanced MEROX (E-MEROX) unit (1030), and a steam cracker complex (1215). The MEROX unit (1010) and the advanced MEROX (E-MEROX) unit (1030) operate similarly to those in Figures 1-5, and like reference numbers represent like units / feeds. In certain embodiments, it may be preferred to send the ODSO compound and the steam cracker feed to the steam cracker through separate inlets.

[0087] All or a portion of the by-product stream of DSO compounds (1007) from the MEROX unit (1010) is sent via stream (1022) to the E-MEROX unit (1030) for conversion to an ODSO stream (1042). The steam cracker feed (1202) and the ODSO stream (1042) (or the DSO / ODSO stream (1046)) are sent via separate inlets to the steam cracking complex (1215) along with a steam source (1223). In this embodiment, the steam cracker feed (1202) and the ODSO stream (1042) (or the DSO / ODSO stream (1046)) are internally mixed within the steam cracking complex (1215) prior to pyrolysis.

[0088] In a similar manner as described with reference to FIG. 5, all or a portion of the DSO stream (1007), stream (1024), can be mixed with the ODSO stream (1042) to produce a combined DSO / ODSO stream (1046), which is then sent to a steam cracking complex (1215).

[0089] The ODSO components and / or combination of DSO / ODSO components present in the steam cracker complex (1215) help minimize or inhibit coke formation on the cracker coils and also protect the metallurgy of the steam cracker.

[0090] In certain embodiments, the amount of ODSO stream (1042) or combined DSO / ODSO stream (1046) that may be added to the steam cracker feed (1202) may range from 10 to 1000 ppmw, 10 to 500 ppmw, 10 to 300 ppmw, or 10 to 100 ppmw. The amount of ODSO or ODSO / DSO compounds added to the steam cracker feed is independent of whether the ODSO compounds are added to the steam cracker feed prior to introduction to the steam cracker or whether the ODSO compounds are added directly into the steam cracker.

[0091] Referring to FIG. 7, as previously discussed, in some embodiments, the steam cracking complex (1215) includes a steam cracking zone (1220) and other additional downstream processing units to produce at least pyrolysis gasoline (1226) and pyrolysis fuel oil (1228), as well as hydrogen (1232), fuel gas (1234), ethylene (1236), propane (1246), propylene (1248), 1,3-butadiene product (1252), methyl tertiary butyl ether (1262), and 1-butene product streams (1268) as shown in FIG. 7.

[0092] FIG. 7 includes a steam cracker feed (1221), which represents the advanced steam cracker feed (1222) of FIG. 3 and FIG. 5, or the steam cracker feed (1202) and an ODSO stream (1042) (or DSO / ODSO stream (1046)) sent via separate inlets to the cracker of FIG. 4 and FIG. 6. The steam cracker feed (1221) and a steam source (1223) are introduced into a steam cracking zone (1220) operating as a large-scale or small-scale thermal cracking process, typically where the steam cracker feed (1221) is converted into a mixed product stream (1224) containing primarily mixed C1-C4 paraffins and olefins, and where pyrolysis gasoline (1226) and pyrolysis fuel oil (1228) are co-produced.

[0093] During operation of the steam cracking zone (1220), the effluent from the cracking furnace is quenched (not shown), for example using a heat transfer line exchanger, and sent to a quench tower. The light products, the quenched cracked gas stream, are sent to the olefin recovery zone (1230). The heavy products are separated in the hot distillation section. The raw pyrolysis fuel oil stream (1228) is recovered in the quench system. The pyrolysis gasoline (1226) is separated in a primary fractionator (not shown) prior to the quench tower.

[0094] During operation of one embodiment of the steam cracking zone (1220), the feedstock is preheated in the convection section. The preheated feedstock is fed into a tubular reactor attached to the radiant or pyrolysis section of the cracking furnace. The hydrocarbons undergo free radical pyrolysis reactions to form the light olefins ethylene and propylene, as well as other by-products. In certain embodiments, dedicated cracking furnaces are provided with cracking tube geometries optimized for each of the major feedstock types, including ethane, propane, and butane / naphtha. Less valuable hydrocarbons, such as ethane, propane, C4 raffinate, and aromatics raffinate, are also produced within the integrated system and process, but are recycled to the steam cracking zone (1220) until consumed.

[0095] In a particular embodiment, the cracked gas from the furnace is cooled in a heat transfer line exchanger (quench cooler) to produce, for example, 1800 psig steam suitable as dilution steam. The quenched cracked gas enters a primary fractionator associated with a steam cracking complex (1215) to strip the pyrolysis fuel oil bottoms from lighter components. The primary fractionator allows for efficient recovery of pyrolysis fuel oil. The pyrolysis fuel oil is stripped with steam in a fuel oil stripper to control the product vapor pressure and to cool. Secondary quenching can also be achieved by injecting pyrolysis fuel oil directly into the liquid furnace effluent as quench oil. The stripped and cooled pyrolysis fuel oil can be sent to a fuel oil pool or product storage. The primary fractionator overhead is sent to a quench water tower; compressed dilution steam for process water treatment and raw pyrolysis gasoline are recovered. The quench water tower overhead is sent to the olefin recovery zone (1230), specifically the first compression stage. The raw pyrolysis gasoline is sent to a gasoline stabilizer to remove any light ends and to control the steam pressure in downstream pyrolysis gasoline processing. A closed loop dilution steam / process water system is possible, where dilution steam is generated using heat recovery from the primary fractionator quench pump-around loop. The primary fractionator allows for efficient recovery of pyrolysis fuel oil due to the energy integration and pyrolysis fuel oil content in the light ends stream.

[0096] The mixed product stream (1224) effluent from the steam cracking zone (1220) is sent to an olefin recovery zone (1230). For example, the light ends from the quenching step, C4-, H2, and H2S, are included in the mixed product stream sent to the olefin recovery zone (1230). The products include: hydrogen (1232), which is recycled and / or sent to uses; fuel gas (1234), which may be sent to the fuel gas system; ethane (1242), which is recycled to the steam cracking zone (1220); ethylene (1236), which is recovered as a product; a mixed C3 stream (1238), which is sent to the methylacetylene / propadiene saturates and propylene recovery zone (1244); and a mixed C4 stream (1240), which is sent to the butadiene extraction zone (1250).

[0097] The olefin recovery zone (1230) operates to produce light olefin (ethylene and propylene) products that meet specifications from the mixed product stream. For example, the cooled gas intermediate product from the steam cracker is fed to a cracked gas compressor, a caustic wash zone, and one or more separation trains to separate the products by distillation. In one particular embodiment, two trains are provided. The distillation train includes a cryogenic distillation section, and the lighter products, such as methane, hydrogen, ethylene, and ethane, are separated in a cryogenic distillation / separation operation. The mixed C2 stream from the steam cracker contains acetylene, which is hydrogenated in an acetylene selective hydrogenation unit to produce ethylene. The system can also include ethylene, propane, and / or propylene cooling facilities to allow for cryogenic distillation.

[0098] In one embodiment, the mixed product stream (1224) leaving the steam cracking zone (1220) passes through 3-5 stages of compression. Acid gases are removed using caustic in a caustic scrubber. After further stages of compression and drying, the light cracked gas is cooled and sent to a depropanizer. In a particular embodiment, the light cracked gas is cooled in a cascaded two-level refrigeration system (propylene, mixed binary refrigerant) for cryogenic separation. The front-end depropanizer optimizes the cooling train and the demethanizer load. The depropanizer separates C3 and lighter cracked gases as an overhead stream and C4 and heavier hydrocarbons as a bottom stream. The depropanizer bottoms are sent to a debutanizer, which recovers a crude C4 stream (1240) and any traces of pyrolysis gasoline.

[0099] The depropanizer overhead passes through a series of acetylene conversion reactors and then is fed to a demethanizer quench train which separates the rich hydrogen product via a hydrogen purification system, such as pressure swing adsorption. Front-end acetylene hydrogenation is implemented to optimize temperature control, minimize green oil formation, and simplify ethylene product recovery by eliminating the C2 splitter pasteurization section, which would otherwise typically be included in product recovery. Hydrogen purification via pressure swing adsorption also eliminates the need for a methanation reactor, which would otherwise typically be included in product recovery.

[0100] The demethanizer recovers methane overhead for fuel gas and C2 and heavier gases at the demethanizer bottoms for delivery to the deethanizer. The deethanizer separates ethane and ethylene overheads, which are fed to the C2 splitter. The C2 splitter recovers an ethylene product overhead (1236), and in certain embodiments, a polymer-purity ethylene product. Ethane (1242) from the C2 splitter bottoms is recycled to the steam cracking zone (1220). The deethanizer bottoms contain C3 from which a propylene product (1248), and in certain embodiments, a polymer-purity propylene product, is recovered overhead to the C3 splitter, and propane (1246) from the C3 splitter bottoms is recycled to the steam cracking zone (1220).

[0101] A methylacetylene / propadiene (MAPD) ​​saturation and propylene recovery zone (1244) is provided to convert the methylacetylene / propadiene for selective hydrogenation and to recover propylene from the mixed C3 stream (1238) exiting the olefin recovery zone (1230). The mixed C3 (1238) exiting the olefin recovery zone (1230) contains significant amounts of propadiene and propylene. The methylacetylene / propadiene saturation and propylene recovery zone (1244) allows for the production of propylene (1248), which in certain embodiments can be polymeric purity propylene.

[0102] The methylacetylene / propadiene saturates and propylene recovery zone (1244) receives hydrogen and mixed C3 (1238) from the olefin recovery zone (1230). The products from the methylacetylene / propadiene saturates and propylene recovery zone (1244) are propylene (1248) and a recycled C3 stream (1246), where propylene (1248) is recovered and the recycled C3 stream (1246) may be sent to the steam cracking zone (1220). In certain embodiments, the hydrogen used to saturate the methylacetylene and propadiene is derived from hydrogen (1232) obtained from the olefin recovery zone (1230).

[0103] The stream (1240) from the olefin recovery zone (1230) containing the C4 mixture, known as crude C4, is sent to a butadiene extraction zone (1250) to recover a high purity 1,3-butadiene product (1252) from the mixed crude C4. In certain embodiments (not shown), the mixed C4 hydrogenation step prior to the butadiene extraction zone (1250) can be integrated with a suitable catalytic hydrogenation process, for example using a fixed bed reactor, to remove acetylenic compounds. 1,3-butadiene (1252) is recovered from the hydrogenated mixed C4 stream by extractive distillation, for example using n-methyl-pyrrolidone (NMP) or dimethylformamide (DMF) as a solvent. The butadiene extraction zone (1250) also produces a raffinate stream (1254) containing butanes / butenes, which is sent to a methyl tertiary butyl ether zone (1256).

[0104] In one embodiment, in operation in the butadiene extraction zone (1250), stream (1240) is preheated and vaporized to a first extractive distillation column, which may, for example, have two sections. NMP or DMF solvent separates the 1,3-butadiene from other C4 components in stream (1254). The enriched solvent is flashed with vaporized gas to a second extractive distillation column, which produces a high purity 1,3-butadiene stream as an overhead product. The flash and liquid solvent from the bottom of the second distillation column are sent to a primary solvent recovery column. The bottom liquid is recycled to the extractor, and the overhead liquid is sent to a secondary solvent recovery or solvent polishing column. The vaporized overhead from the recovery column is combined with recycled butadiene product to the bottom of the extractor to increase the concentration of 1,3-butadiene. The 1,3-butadiene product (1252) can be water washed to remove any traces of solvent. In certain embodiments, the product purity (wt%) is 97-99.8, 97.5-99.7, or 98-99.6 1,3-butadiene; 94-99, 94.5-98.5, or 95-98 (wt%) of the 1,3-butadiene content of the feedstock is recovered. In addition to the solvent, such as DMF, additive chemicals are blended into the solvent to improve butadiene recovery. The extractive distillation column and primary solvent recovery column are also reboiled using high pressure steam (e.g., 600 psig) and circulating hot oil from a separate source as heat exchange fluids.

[0105] A methyl tertiary butyl ether zone (1256) is integrated to produce methyl tertiary butyl ether (1262) and a second C4 raffinate (1260) from the first C4 raffinate stream (1254). In certain embodiments, the C4 raffinate 1 (1254) is subjected to selective hydrogenation to selectively hydrogenate any remaining dienes to produce methyl tertiary butyl ether prior to the reaction of isobutene with methanol.

[0106] Purity specifications for the recovery of the 1-butene product stream (1268) require reduced levels of isobutylene in the second C4 raffinate (1260). Typically, the first C4 raffinate stream (1254), which contains mixed butanes and butenes, is sent to the methyl tertiary butyl ether zone (1256), also containing isobutylene. Methanol (1258) is also added, which reacts with the isobutylene to produce methyl tertiary butyl ether (1262). For example, the methyl tertiary butyl ether product and methanol are separated in a series of fractionation columns and sent to the second reaction stage. Methanol is removed in a water wash and final fractionation stage.

[0107] In one embodiment of the operation of the methyl tertiary butyl ether zone (1256), the raffinate stream (1254) contains 35-45%, 37-42.5%, 38-41%, or 39-40% isobutylene by weight. This component is removed from the C4 raffinate (1260) to achieve the required purity specification, for example, 98% by weight or greater with respect to the 1-butene product stream (1268) exiting the butene-1 recovery zone (1266). Methanol (1258), which in certain embodiments is high purity methanol having a purity level of 98% by weight or greater from outside the confines of the unit, is reacted in the primary reactor with isobutylene contained in the raffinate stream (1254) and, in certain embodiments, from the optional metathesis step. In certain embodiments, the primary reactor is a fixed bed downflow dehydrogenation reactor and is operated to convert isobutylene to about 70-95%, 75-95%, 85-95%, or 90-95% by weight. The effluent from the primary reactor is sent to the reaction tower where the reaction is completed. In certain embodiments, heat from the reaction tower and primary reactor exotherms can be optionally used to supplement the tower reboiler along with the steam provided. The reaction tower bottoms contain methyl tertiary butyl ether, trace amounts of unreacted methanol, e.g., less than 2%, and heavy products produced in the primary reactor and reaction tower. The reaction tower overhead contains unreacted methanol and unreacted C4 raffinate. This stream is water washed to remove unreacted methanol before being sent to the 1-butene recovery zone (1266) as C4 raffinate (1260). The recovered methanol is separated from the wash water in a methanol recovery column and recycled to the primary reactor.

[0108] The C4 raffinate stream (1260) exiting the methyl tertiary butyl ether zone (1256) is sent to a separation zone (1266) for butene-1 recovery. In certain embodiments, a selective hydrogenation zone (not shown) may also be included upstream of the methyl tertiary butyl ether zone (1256) or between the methyl tertiary butyl ether zone (1256) and the separation zone (1266) for butene-1 recovery. For example, in certain embodiments, the raffinate exiting the methyl tertiary butyl ether zone (1256) is selectively hydrogenated in a selective hydrogenation unit to produce butene-1. Other comonomers and paraffins are also coproduced. The selective hydrogenation zone operates in the presence of an effective amount of hydrogen from hydrogen recycled within the selective hydrogenation zone and from make-up hydrogen; in certain embodiments, all or a portion of the make-up hydrogen for the selective hydrogenation zone is derived from the steam cracker hydrogen stream (1232) exiting the olefin recovery train (1230).

[0109] One or more separation steps are used for the selective recovery of the 1-butene product stream (1268) as well as the recovery of a recycle stream (1264) sent to the steam cracking zone (1220). For example, 1-butene can be recovered using two separation columns, the first column recovering olefins from paraffins and the second column separating 1-butene from a mixture containing 2-butene that is blended with the paraffins leaving the first column and recycled to the steam cracker as the recycle stream (1264).

[0110] In certain embodiments, the C4 raffinate stream (1260) exiting the methyl tertiary butyl ether zone (1256) is sent to a first splitter where isobutane, 1-butene, and n-butane are separated from the heavier C4 components. Isobutane, 1-butene, and n-butane are recovered overhead, condensed in an air cooler, and sent to a second splitter. The bottoms exiting the first splitter contain primarily cis- and trans-2-butenes, which can be added to the recycle stream (1264). In certain configurations, the overhead of the first splitter enters the middle section of a second splitter. An isobutane product can optionally be recovered overhead, a 1-butene product (1268) is recovered as a sidecut, and n-butane is recovered as a bottoms stream. The bottoms from both splitters are recovered as all or part of the recycle stream (1264).

[0111] The steam cracking zone (1220) is operated under parameters effective to crack the feedstock into desired products including ethylene, propylene, butadiene, and mixed butenes. Pyrolysis gasoline and pyrolysis oil are also recovered. In certain embodiments, the steam cracking furnace(s) is operated under conditions effective to produce an effluent having a propylene to ethylene weight ratio of about 0.3 to 0.8, 0.3 to 0.6, 0.4 to 0.8, or 0.4 to 0.6.

[0112] The steam cracking zone (1220) typically includes one or more furnace trains. In certain embodiments, the ODSO stream (1042) (or the DSO / ODSO stream (1046)) may be injected into any or all of the one or more furnaces in the steam cracking furnace (1220).

[0113] In certain embodiments, one or more ODSO streams (1042) may be injected into the steam cracker (1220). In some embodiments, one or more DSO / ODSO streams (1046) may be injected into the steam cracker (1220). In some embodiments, one or more ODSO streams (1042) and one or more DSO streams (1024) derived from the DSO stream (1007) may be injected into the steam cracker (1220).

[0114] In certain embodiments (not shown), a portion of the ODSO stream (1042) and the DSO stream (1024) may be injected into one or more different furnaces of the steam cracking zone (1220). For example, in certain embodiments, the ODSO stream (1042) may be injected into a first one of the one or more furnaces of the steam cracking furnace (1220) and the DSO stream (1024) may be injected into a second one of the one or more furnaces of the steam cracking furnace (1220). These are not limiting examples, and various variations in possible injection points of the ODSO stream(s) (1042), the DSO / ODSO stream(s) (1046), and / or the DSO stream(s) derived from the DSO stream (1024) will be apparent to those skilled in the art.

[0115] A typical configuration for the steam cracking zone (1220) comprises a reactor operable according to the well-known steam pyrolysis process, i.e., by introducing pyrolysis feedstock into a convection section in the presence of steam to raise the temperature of the feedstock, and passing the heated feedstock to a radiant or pyrolysis reactor comprising furnace tubes for cracking. In the convection section, the mixture is heated to a predetermined temperature, for example, using one or more waste heat streams or other suitable heating arrangements.

[0116] The feed mixture is heated to an elevated temperature in the convection section, and materials with boiling points below a predetermined temperature are vaporized. The heated mixture (in certain embodiments, along with additional steam) is passed to a pyrolysis section operating at an elevated temperature, where it has a short residence time, e.g., less than 1-2 seconds, to undergo pyrolysis to produce a mixed product stream.

[0117] In certain embodiments, separate convection and radiant sections are used for different feedstocks entering the steam cracking zone (1220), with conditions for each optimized for the particular feedstock.

[0118] In certain embodiments, the steam cracking in the steam cracking zone (1220) is carried out using the following conditions: a convection section temperature (°C) in the range of about 400-600, 400-550, 450-600, or 500-600; a convection section pressure (barg) in the range of about 4.3-4.8, 4.3-4.45, 4.3-4.6, 4.45-4.8, 4.45-4.6, or 4.6-4.8; a pyrolysis section temperature (°C) in the range of about 650-950, 650-900, 650-850, 700-950, 700-900, 700-850, 750-950, the pressure (barg) in the pyrolysis section is in the range of about 1-4, 1-2 or 1-1.4; the steam to hydrocarbon ratio in the convection section is in the range of about 0.3:1-2:1, 0.3:1-1.5:1, 0.5:1-2:1, 0.5:1-1.5:1, 0.7:1-2:1, 0.7:1-1.5:1, 1:1-2:1 or 1:1-1.5:1; the residence time (seconds) in the pyrolysis section is in the range of about 0.05-1.2, 0.05-1, 0.1-1.2, 0.1-1, 0.2-1.2, 0.2-1, 0.5-1.2 or 0.5-1. EXAMPLES

[0119] A hydrotreated diesel sample (whose properties and composition are shown in Table 3) obtained from a commercial hydrotreating unit was steam cracked in a bench-scale steam cracking unit. The reactor unit is representative of a conventional steam cracker unit. The feedstock was doped with a blend of disulfide oil and oxidized disulfide oil mixed in a 50:50 weight ratio at a concentration of 210 ppmw. The DSO in the blend is the DSO characterized in Table 1. The ODSO in the blend is the product of oxidation of the DSO characterized in Table 1 via the E-MEROX process. The reactor operating conditions were: temperature 675 °C, reactor outlet pressure 1 bar. The mass flow rate of the hydrocarbons (HC) was fixed to achieve an average residence time of 8 seconds. The steam dilution factor was set to 0.6 kg HO / kg HC·s.

[0120] [Table 3]

[0121] The product yields of the examples are shown in Table 4. Product yields for liquid and gaseous products were normalized to 100%W.

[0122] [Table 4]

[0123] The addition of the otherwise waste products to the steam cracking complex not only achieves the benefit of minimizing or inhibiting coke formation on the cracker coils and protecting the metallurgy of the steam cracker, but also provides an environmentally friendly means of disposal of the by-product waste and eliminates the need to purchase industrial chemicals such as DMDS that would otherwise be required to minimize coke formation. Further advantages of the processes described herein include the elimination or reduction of waste storage and treatment units and costs that would otherwise be required for the disposal of DSO and / or ODSO waste.

[0124] From the foregoing, it can be seen that the process of the present disclosure provides a cost-effective and environmentally acceptable means for disposing of by-product oxidized disulfide oils, and allows the conversion of an essentially low-value refinery material into commercially important coke inhibition and metallurgical protection products.

[0125] The process of the present invention has been described above and in the accompanying drawings; modifications and variations of the process will be apparent to those skilled in the art from this specification, and the scope of protection is determined by the claims which follow. [Explanation of symbols]

[0126] Hydrocarbon Streams (1) Caustic Solution (2) Hydrocarbon Product Stream (3) (4) A combined stream of spent caustic solution and alkali metal alkanethiolates Catalyst (5) Air(6) By-Product Streams (7) Reclaimed Spent Caustic Solution (8) Extraction tank (10) Reactor (20) Reactor (30) Catalysts (32) Oxidizing agents (34) Mixed Stream (36) Conventional separation tank (40) ODSO compound(42) By-products (44) DSO Stream, DSO Compound (1007) MEROX Unit (1010) Stream(1022) DSO Stream (1024) Improved MEROX (E-MEROX) unit (1030) ODSO Stream (1042) Combined DSO / ODSO Streams (1046) Steam Cracker Feed (1202) Steam Cracking Complex (1215) Steam cracking area (1220) Steam Cracker Feed (1221) Improved Steam Cracker Feed (1222) Steam Source(1223) Mixed Product Stream (1224) Mixed Gas Product Stream, Steam Cracker Product (1225) Pyrolysis gasoline(1226) Pyrolysis fuel oil (1228) Olefins Recovery Area (1230) Hydrogen(1232) Fuel Gas(1234) Ethylene(1236) Mixed C3 Stream (1238) Mixed C4 Stream (1240) Ethane(1242) Methylacetylene / propadiene saturation and propylene recovery area (1244) Propane(1246) Propylene Products(1248) Butadiene Extraction Area (1250) High Purity 1,3-Butadiene Product (1252) Raffinate Stream, First C4 Raffinate Stream (1254) Methyl tertiary butyl ether (1256) Methanol(1258) Second C4 Raffinate (1260) Methyl tertiary butyl ether (1262) Circular Use Stream (1264) Butene-1 Recovery Area (1266) 1-Butene Product Stream (1268)

Claims

1. introducing said oxidized disulfide oil (ODSO) stream and said steam cracker feed stream into a steam cracking complex; mixing the ODSO stream and the steam cracker feed stream within the steam cracking complex to produce an internal steam cracker mixture comprising an ODSO component; and subjecting the internal steam cracker mixture to thermal cracking in the steam cracking complex to produce a steam cracker product; A steam cracking process comprising: During the pyrolysis, the ODSO component in the inner steam cracker mixture minimizes coke formation on the steam cracker coils; The ODSO component is obtained by catalytic oxidation of disulfide oil compounds contained in the mixture and derived from mercaptan oxidation; the mixture comprises one or more oxidized disulfide compounds selected from the group consisting of ODSO compounds having the general formula (R-SO-S-R'), (R-SOO-S-R'), (R-SOO-SO-R'), (R-SOO-SOO-R'), (R-SO-SO-R'), (R-SO-SOO-OH), (R-SOO-SOO-OH), (R-SO-SO-OH), (R-SOO-SO-OH), (R'-SO-SO-OR), (R'-SOO-SO-OR), (R'-SO-SOO-OR) and (R'-SOO-SOO-OR); R and R' are the same or different C 1-10 alkyl or C 6-10 aryl; method.

2. combining all or a portion of a disulfide oil (DSO) stream derived from an effluent refinery hydrocarbon stream recovered downstream of a MEROX process with the ODSO stream prior to introduction into the steam cracking complex to produce a combined ODSO / DSO stream mixed with the steam cracker feed; the steam cracker mixture comprises ODSO and DSO components; 10. The method of claim 1, wherein the ODSO and DSO components in the steam cracker mixture during pyrolysis minimize coke formation on steam cracker coils.

3. combining an oxidized disulfide oil (ODSO) stream with a steam cracker feed stream to produce an improved steam cracker feed comprising an ODSO component; introducing said improved steam cracker feed into a steam cracking complex; and subjecting said advanced steam cracker feed to thermal cracking in said steam cracking complex to produce a steam cracker product; A steam cracking process comprising: During the pyrolysis, the ODSO component in the advanced steam cracker feed minimizes coke formation on steam cracker coils; The ODSO component is obtained by catalytic oxidation of disulfide oil compounds contained in the mixture and derived from mercaptan oxidation; the mixture comprises one or more oxidized disulfide compounds selected from the group consisting of ODSO compounds having the general formula (R-SO-S-R'), (R-SOO-S-R'), (R-SOO-SO-R'), (R-SOO-SOO-R'), (R-SO-SO-R'), (R-SO-SOO-OH), (R-SOO-SOO-OH), (R-SO-SO-OH), (R-SOO-SO-OH), (R'-SO-SO-OR), (R'-SOO-SO-OR), (R'-SO-SOO-OR) and (R'-SOO-SOO-OR); R and R' are the same or different C 1-10 alkyl or C 6-10 aryl; method.

4. combining all or a portion of a disulfide oil (DSO) stream resulting from an effluent refinery hydrocarbon stream recovered downstream of a MEROX process with said OSDO stream prior to mixing with said steam cracker feed stream to produce a combined ODSO / DSO stream mixed with said steam cracker feed; the improved steam cracker feed comprises ODSO and DSO components; 4. The method of claim 3, wherein the ODSO and DSO components in the advanced steam cracker feed during the pyrolysis minimize coke formation on steam cracker coils.

5. 5. The method of claim 2 or 4, wherein the DSO stream comprises one or more disulfide compounds.

6. 5. The method of claim 2 or 4, wherein the DSO stream is mixed with the ODSO stream in a ratio of ODSO to DSO components ranging from 100:0 to 95:

5.

7. 4. The process of claim 1 or 3, wherein the ratio of the ODSO stream to the steam cracker feed prior to pyrolysis is in the range of 10 to 1000 ppmw.

8. 5. The process of claim 2 or 4, wherein the proportion of the combined ODSO / DSO stream to the steam cracker feed prior to pyrolysis is in the range of 10 to 1000 ppmw.

9. the steam cracking complex comprises a steam cracking zone, an olefin recovery zone, a methyl acetylene / propadiene saturation and propylene recovery zone, a butadiene extraction zone, a methyl tertiary butyl ether zone, and a butene-1 recovery zone; 4. The method of claim 1 or 3, wherein the steam cracker products include hydrogen, fuel gas, ethylene, propane, propylene, 1,3-butadiene product, methyl tertiary butyl ether, 1-butene product stream, pyrolysis gasoline, and pyrolysis fuel oil.

10. At a temperature in the convection section in the range of 400 to 600, 400 to 550, or 500 to 600 °C, at a pressure in the convection section in the range of 4.3 to 4.8, 4.3 to 4.6 or 4.6 to 4.8 barg; At a temperature in the pyrolysis section ranging from 650 to 950, 650 to 900 or 650 to 850° C. a pressure in the pyrolysis section in the range of 1 to 4, 1 to 2 or 1 to 1.4 barg; a steam to hydrocarbon ratio in the convection section ranging from 0.3:1 to 2:1, 0.5:1 to 1.5:1, or 1:1 to 1.5:1; and A residence time in the pyrolysis section ranging from 0.05 to 1.2, 0.2 to 1.2, or 0.5 to 1 seconds; The method of claim 10, wherein the steam cracking zone is operated.

11. 4. The method of claim 1 or 3, wherein the steam cracker feed is selected from the group consisting of one or more of light hydrocarbons, light hydrocarbon gases containing 2 to 4 carbon atoms, light naphtha paraffinic hydrocarbons containing 5 to 6 carbon atoms, heavy naphtha hydrocarbons containing paraffins, naphthenes, aromatics having a carbon number in the range of 7 to 12, middle distillate hydrocarbons containing paraffins, naphthenes or aromatics having a boiling point in the range of 180 to 370° C., straight run or hydrotreated vacuum gas oils having a boiling point in the range of 370 to 565° C., diesel fuel, and ultra low sulfur diesel fuel having less than 10 ppm sulfur.

12. 4. The method of claim 1 or 3, wherein the ODSO or the ODSO and DSO components present in the steam cracking complex during the pyrolysis protect the metallurgy of the steam cracking complex.

13. 4. The method of claim 1 or 3, wherein the ODSO component is comprised in a mixture from the oxidation of a DSO compound, the mixture comprising dialkyl-thiosulfoxides (R-SO-S-R'), dialkyl-thiosulfones (R-SOO-S-R'), dialkyl-sulfone sulfoxides (R-SOO-SO-R'), dialkyl-disulfones (R-SOO-SOO-R'), dialkyl-disulfoxides (R-SO-SO-R'), alkyl-sulfoxide sulfonates (R-SO-SOO-OH), alkyl-sulfone sulfonates (R-SOO-SOO-OH), alkyl-sulfoxide sulfinates (R-SO-SO-OH) and alkyl-sulfonesulfinates (R-SOO-SO-OH).

Images