Publication number WO A2 Publication type Application Application number PCT/US2006/046704 Publication date Aug 2, 2007 Filing date Dec 7, 2006 Priority date Jan 13, 2006 Also published as,, Publication number PCT/2006/46704, PCT/US/2006/046704, PCT/US/2006/46704, PCT/US/6/046704, PCT/US/6/46704, PCT/US2006/046704, PCT/US2006/46704, PCT/US, PCT/US200646704, PCT/US6/046704, PCT/US6/46704, PCT/US6046704, PCT/US646704, WO 2007/087017 A2, WO A2, WO A2, WO-A2-, WO2007/087017A2, WO A2, WOA2 Inventors, Applicant Export Citation,, (4), (5), (3) External Links. Sattam Oru Iruttarai Video Songs Download. USE OF STEAM CRACKED TAR FIELD OF THE INVENTION [0001] The invention relates to a method for improving the solubility of steam cracked tar in useful compositions. In an embodiment, the upgraded steam cracked tar is added to fuel oil. BACKGROUND OF THE INVENTION [0002] Steam cracking, also referred to as pyrolysis, has long been used to crack various hydrocarbon feedstocks into olefins, preferably light olefins such as ethylene, propylene, and butenes. Conventional steam cracking utilizes a pyrolysis furnace that has two main sections: a convection section and a radiant section.

In the conventional pyrolysis furnace, the hydrocarbon feedstock enters the convection section of the furnace as a liquid (except for light feedstocks which enter as a vapor) wherein it is heated and vaporized by indirect contact with hot flue gas from the radiant section and optionally by direct contact with steam. The vaporized feedstock and steam mixture (if present) is then introduced through crossover piping into the radiant section where the cracking takes place.

The resulting products comprising olefins leave the pyrolysis furnace for further downstream processing. [0003] Pyrolysis involves heating the feedstock sufficiently to cause thermal decomposition of the larger molecules. Among the valuable and desirable products include light olefins such as ethylene, propylene, and butylenes. Tony Christie Rapidshare Premium. The pyrolysis process, however, also produces molecules that tend to combine to form high molecular weight materials known as steam cracked tar or steam cracker tar, hereinafter referred to as 'SCT'. These are among the least valuable products obtained from the effluent of a pyrolysis furnace.

In general, feedstocks containing higher boiling materials ('heavy feeds') tend to produce greater quantities of SCT. [0004] SCT is among the least desirable of the products of pyrolysis since it finds few uses. SCT tends to be incompatible with other 'virgin' (meaning it has not undergone any hydrocarbon conversion process such as FCC or steam cracking) products of the refinery pipestill upstream from the steam cracker. At least one reason for such incompatibility is the presence of asphaltenes. Asphaltenes are very high in molecular weight and precipitate out when blended in even insignificant amounts into other materials, such as fuel oil streams. [0005] One way to avoid production of SCT is to limit conversion of the pyrolysis feed, but this also reduces the amount of valuable products such as light olefins. Another solution is to 'flux' or dilute SCT with stocks that do not contain asphaltenes, but this also requires the use of products that find higher economic value in other uses.

[0006] In US 4,446,002, the precipitation of sediment in unconverted residuum obtained from a virgin residuum conversion process is taught to be suppressed by blending the unconverted residuum with an effective amount of a virgin residuum having an asphaltene content of at least about 8 wt% of the virgin residuum at a temperature sufficient to maintain both residuum components at a viscosity of no greater than about 100 cSt (centistokes) during blending. Virgin residuum is the bottoms product of the atmospheric distillation of petroleum crude oil at temperatures of about 357 to 385°C. [0007] In US 5,443,715, steam cracked tar is upgraded by mixing with a 'hydrogen donor', preferably hydrotreated steam cracked tar, at or downstream of quenching of the effluent of a gas oil steam cracker furnace. In this regard, see also US 5,215,649; and US 3,707,459; and WO 9117230. [0008] Other references of interest include US 3,622,502; US 3,691,058; US 4,207,168; US 4,264,334; WO 91/13951; DE 4308507; and JP 58-149991.

[0009] There has recently been described a process wherein a pyrolysis furnace feedstock is provided to the convection section of the pyrolysis furnace, whereby at least a portion of the feedstock is vaporized, followed subsequently by passing the at least partially vaporized feedstock, optionally with steam, to a flash drum, wherein a vapor phase and liquid phase are separated. The vapor phase is fed to the radiant section of a pyrolysis furnace, and products, including desirable light olefins, are obtained as effluent of the furnace. The liquid phase or bottoms product of the flash drum contains substantially all of the asphaltenes (if present) in the feedstock. Such processes and apparatus therefore are described in US Applications 20; 7; 20; 20; 20; 20; 20; 20; 20; 20; 20; 20; and 20. [0010] The present inventors have surprisingly discovered that SCT is highly compatible with the flash drum bottoms product in the aforementioned processes, and the two materials may be blended to produce a composition having higher solubility in various petroleum products, particularly fuel oils, e.g., heavy fuel oils or Bunker fuels. SUMMARY OF THE INVENTION [0011] The invention is direct to a process wherein the liquid or bottoms product of a flash drum downstream from the convection section inlet of a pyrolysis furnace and upstream of the crossover piping to the radiant section of said pyrolysis furnace is obtained and mixed with steam cracked tar (SCT).

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[0012] In preferred embodiments, the mixture of said bottoms product and said SCT is subsequently mixed with fuel oils and/or Bunker fuels (and optionally flux). [0013] The invention is also directed to a composition comprising steam cracked tar (SCT) and the liquid or bottoms product of a flash drum integrated with a pyrolysis furnace. [0014] In any of the aforementioned embodiments, SCT is optionally fluxed. [0015] In any of the aforementioned embodiments, the SCT is optionally mixed with steam cracked gas oil (SCGO) and/or atmospheric gas oil (AGO). [0016] In preferred embodiments of any of the aforementioned embodiments, the composition of the invention further comprises fuel oils, such as heavy fuel oils and/or Bunker fuels.

[0017] It is an object of the invention to compatibilize SCT for economically useful purposes, such as for use in fuels for diesel engines in large machinery. [0018] These and other objects, features, and advantages will become apparent as reference is made to the following detailed description, preferred embodiments, examples, and appended claims.

DETAILED DESCRIPTION [0019] The invention is direct to a process wherein the liquid or bottoms product of a flash drum downstream from the convection section inlet of a pyrolysis furnace and upstream of the crossover piping to the radiant section of said pyrolysis furnace is obtained and mixed with SCT. Liquid product and bottoms products are synonymous with regard to the flash drum components. As used herein, the phrase 'bottoms product of a flash drum integrated with a (or 'said') pyrolysis furnace' will mean 'liquid or bottoms product of a flash drum downstream from the convection section inlet of a pyrolysis furnace and upstream of the crossover piping to the radiant section of said pyrolysis furnace' for the sake of brevity.

[0020] The term 'pyrolysis furnace' is used herein to be synonymous with the term 'steam cracker'. It is also known in the art as a 'thermal pyrolysis furnace'. Steam, although optional, is typically added inter alia to reduce hydrocarbon partial pressure, to control residence time, and to minimize coke formation. In preferred embodiments of the present invention, the steam may be superheated, such as in the convection section of the pyrolysis unit, and/or the steam may be sour or treated process steam. [0021] According to the present invention, a feedstream is provided to the inlet of a convection section of a pyrolysis unit, wherein it is heated so that at least a portion of the feedstream is in the vapor phase. Steam is optionally but preferably added in this section and mixed with the feedstream. The heated feedstream with optional steam and comprising a vapor phase and a liquid phase is then flashed in a flash drum to drop out the heaviest fraction (e.g., asphaltenes), and further processing the overheads from the flash drum, through crossover piping into the radiant section of a pyrolysis unit.

[0022] One of the advantages of having a flash drum downstream of the convection section inlet and upstream of the crossover piping to the radiant section is that it increases the feedstreams available to be used directly, without pretreatment, as feed to a pyrolysis furnace. Thus, crude oil, even high naphthenic acid containing crude oil and fractions thereof, may be used directly as feed. [0023] The terms 'flash drum', 'flash pot', 'knock-out drum' and knock-out pot' are used interchangeably herein; they are per se well-known in the art. In a preferred embodiment, the composition of the vapor phase leaving the flash drum is substantially the same as the composition of the vapor phase entering the flash drum, and likewise the composition of the liquid phase leaving the flash drum is substantially the same as the composition of the liquid phase entering the flash drum, i.e., the separation in the flash drum consists essentially of a physical separation of the two phases entering the drum. [0024] The preferred flash drum and the of the flash drum with pyrolysis units have previously been described in U.S. Patent Application Publication Nos. 20; 7; 20; 20; 20; 20; 20; 20; 20; 20; 20; 20; and 20.

[0025] Another preferred apparatus effective as a flash drum for purposes of the present invention is described in U.S. 6,632,351 as a 'vapor/liquid separator'. [0026] In the process of the present invention, the flash drum preferably operates at a temperature of from 800 0F (425°C) to 850 0F (455°C). [0027] Surprisingly, it has also been discovered by the present invention that 1000°F+ (538°C and greater) vacuum tower resid fractions from the petroleum refining pipestill is an equivalent of the liquid or bottoms product of the aforementioned flash drum. Thus, this material may also be used alone or mixed with said liquid or bottoms product, provided it is derived from crudes or fractions there of having a low pour point as described in more detail below. [0028] In the present invention, feedstreams may comprise any crude oil or fraction thereof, however it has been found that crudes having Pour Points greater than 15°C do not provide integrated flash drum bottoms product that make good solvents for tar asphaltenes and therefore must be used in very high proportions or require too much fluxing to be beneficially useful.

Preferred feeds are low sulfur (e.g, maximum sulfur content of less than 2.0 wt% or 1.5 wt% or 1.0 wt% or less than 1.0 wt% S), low Pour Point, even more preferably medium weight crudes that are non-waxy. In anohter embodiment, the preferred crudes or fractions thereof having a Pour Point of or 55 wt%, of the liquid or bottoms product of the aforementioned flash drum, with ranges from any of the aforementioned lower values to any of the aforementioned higher values also contemplated. The remainder of the composition is SCT (based on the composition consisting of liquid or bottoms product of the aforementioned flash drum and SCT). Thus, preferred proportions of SCT may also be given as from 20 wt%, or 25 wt%, or 30 wt%, or 40 wt%, or 45 wt%, to 70 wt%, or 60 wt%, or 55 wt%, of SCT, with ranges from any of the aforementioned lower values to any of the aforementioned higher values also contemplated. These proportions do not include fluxant and/or SCGO or AGO, but are based solely on SCT and bottoms of the integrated flash drum.

[0034] SCT thus compatibilized with the liquid or bottoms product of the aforementioned flash drum may be mixed in any proportions with additional materials, advantageously so that no asphaltenes precipitate. [0035] In preferred embodiments, the aforementioned mixture is blended with heavy fuel oils and/or Bunker fuels. Typical specifications are provided below for an RSFO blend meeting the 3S0 centistoke (cSt) requirements for Fuel Oil is given below. For a composition according to the present invention, the most important specifications (with regard to meeting the various specifications for published fuel oil requirements) are Kinematic Viscosity (KV), Specific Gravity (SG) and compatibility (e.g., one or both of the sediment criteria listed below). It is an important and surprising discovery of the present inventors that such specifications can be met for a mixture containing steam cracked tar. [0036] One typical specification for a fuel oil is listed in Table 1. Table 1 RFSO Standard Fuel Oil S ecifications in Sin a ore Platt's.

[0037] Yet another surprising discovery of the present inventors is that the blend according to the invention may be advantageously fluxed with stream cracked gas oil (SCGO). This is a great advantage of the present invention not the least of which because SCGO is another of the products of the pyrolysis furnace that is generally considered undesirable because of lack of end uses. In embodiments, if SCGO or AGO is unavailable, HAGO or HDDO may be used as fluxant. Patent Citations Cited Patent Filing date Publication date Applicant Title * Jan 16, 1928 Sep 15, 1931 Standard Oil Co Fuel oil * Apr 15, 1970 Sep 12, 1972 Exxon Research Engineering Co Production of single-ring aromatic hydrocarbons from gas oils containing condensed ring aromatics and integrating this with the visbreaking of residua * Apr 17, 1970 Dec 26, 1972 Exxon Research Engineering Co Cracking hydrocarbon residua * Jul 3, 2002 Jan 8, 2004 Stell Richard C. Process for steam cracking heavy hydrocarbon feedstocks.