KR20120003872A - Processing of organic acids containing hydrocarbons - Google Patents

Abstract

A method of thermal cracking an organic acid containing hydrocarbon feed, wherein the feed is first treated in a vaporization step and then subjected to thermal cracking.

Description

Treatment of Organic Acid-Containing Hydrocarbons {PROCESSING OF ORGANIC ACIDS CONTAINING HYDROCARBONS}

The present invention relates to thermal cracking an acid containing hydrocarbon feed using an evaporation unit in combination with at least one thermal cracking furnace.

Thermal cracking (pyrolysis) of hydrocarbons is a petrochemical process widely used in the production of olefins such as ethylene, propylene, butene, butadiene and aromatics such as benzene, toluene and xylene.

Basically, the hydrocarbon-containing feedstock is mixed with the vapor, which acts as a diluent, to keep the hydrocarbon molecules separate. The steam / hydrocarbon mixture is preheated to about 900 to about 1,000 degrees Fahrenheit (° F) in the convection zone of the furnace, and then enters the reaction (radiation) zone, where it is subjected to an extreme hydrocarbon heat cracking temperature in the range of about 1,400 to about 1,550 ° F. Heats up very quickly Thermal cracking is carried out without the aid of any catalyst.

This process is carried out in a pyrolysis furnace (steam cracker) at a pressure in the reaction zone in the range of about 10 to about 30 psig. The pyrolysis furnace internally has a convection section (zone) and a separate radiation section (zone). The preheating function is mainly performed in the convection section, while the extreme cracking mostly occurs in the radiation section.

After thermal cracking, depending on the nature of the main feed to the pyrolysis furnace, the emissions from this furnace may contain a wide variety of gaseous hydrocarbons, for example 1 to 35 carbon atoms per molecule. Such gaseous hydrocarbons may be saturated, monounsaturated and polyunsaturated, and may also be aliphatic, cycloaliphatic and / or aromatic. The cracked gas may also contain significant amounts of molecular hydrogen (hydrogen).

The cracked product is then further processed in an olefins production plant to produce, as a product of the plant, a variety of separate individual streams of high purity, for example hydrogen, ethylene, propylene, mixed hydrocarbons having four carbon atoms per molecule, Produces fuel oil and pyrolysis gasoline. Each separate individual stream is itself an important commercial product. Thus, the olefin manufacturing plant recently takes a whole crude stream or a portion (fraction) of condensate, from which a number of separated important products are produced.

Thermal cracking began to be used in 1913 and was first applied to gaseous ethane as the main feed of cracking furnaces for ethylene production. Since then, the industry has evolved to use heavier and more complex hydrocarbon gaseous and / or liquid feeds as the main feed for cracking furnaces. These feeds can now use fractions of whole crude oil or condensate that essentially vaporize completely during thermal cracking. The cracked product may contain, for example, about 1 weight percent (wt%) of hydrogen, about 10 wt% methane, about 25 wt% ethylene, and about 17 wt% propylene, all weight percent It is relative to the total weight of the product and the remainder consists mostly of other hydrocarbon molecules having 4 to 35 carbon atoms per molecule.

Natural gas and the entire crude oil (s) are naturally formed in a number of subterraneangeological formations of widely varying pores. Most of these structures are covered with impermeable rock layers. Natural gas and whole crude oil (crude oil) also accumulate in various stratigraphic traps below the earth's surface. Thus, a huge amount of both natural gas and / or crude oil is concentrated to form a hydrocarbon support structure at various depths below the earth's surface. Most of these natural gases are physically in close contact with crude oil, absorbing a number of light molecules from the crude oil.

When a well bore penetrates into the earth and drills one or more of these hydrocarbon support structures, natural gas and / or crude oil can be recovered through the borehole to the earth's surface.

As used herein, the terms "whole crude oil" and "crude oil" refer to liquids (at temperatures and pressures generally prevailing at the earth's surface), such as from wellheads separated from any natural gas that may be present. Phosphorus crude oil, excluding any processing to allow crude oil to be transferred to crude oil refinery and / or conventional distillation units in such refinery. The treatment will include steps such as desalting. Thus, it is crude oil suitable for distillation or other fractionation in refineries, but without any such distillation or fractionation. This may include non-boiling entities such as asphaltene or tar, but is not always necessary. As such, it is difficult but not impossible to provide a boiling range for the entire crude oil. Thus, the entire crude oil may be one or more crude oils as is from oil field pipelines and / or conventional crude oil storage facilities, as applicability suggests, without any prior fractionation.

Natural gas, like crude oil, varies greatly in composition when produced on the earth's surface, but generally contains a significant amount, mostly major amounts, of about 50% by weight (% by weight) or more of methane. Natural gas also often contains small amounts (less than about 50% by weight), often less than about 20% by weight, of one or more of ethane, propane, butane, nitrogen, carbon dioxide, hydrogen sulfide, and the like. Most, but not all, natural gas streams produced from the earth are not gaseous at small temperatures (less than about 50 weight percent), often less than about 20 weight percent, at temperatures and pressures of ambient atmospheric conditions generally prevailing at the earth's surface, Once produced on the earth's surface, it may contain hydrocarbons having 5 to 12 carbon atoms (C5 to C12) per molecule, which may condense out of natural gas. All weight percentages are relative to the total weight of the natural gas stream in question.

When various natural gas streams are produced at the earth's surface, the hydrocarbon composition naturally condenses out of the natural gas stream produced under temperature and pressure at prevailing conditions at the earth's surface where the stream is focused. Thus, a general liquid hydrocarbon condensate is produced which is separated from natural gas which is generally gaseous under the same prevailing conditions. In general, gaseous natural gas may contain methane, ethane, propane, and butane. Common liquid hydrocarbon fractions condensed from the resulting natural gas stream are generally referred to as “condensates” and generally contain molecules heavier than butane (which may be C5 to about C20 or slightly higher). After separation from the resulting natural gas, this liquid condensate fraction is treated separately from the remaining gaseous fraction, commonly referred to as natural gas.

Thus, the condensate recovered from the natural gas stream first produced on the earth's surface is not exactly the same material, composition as natural gas (mainly methane). Nothing is the same substance, composition as crude oil. Condensate occupies the gap between the general gaseous natural gas and the general liquid whole crude oil. Condensates contain hydrocarbons heavier than ordinary gaseous natural gas and contain hydrocarbons in the hydrocarbon range at the lightest end point of the entire crude oil.

Condensate, unlike crude oil, can be characterized by a boiling range. The condensate generally boils in the range of about 100 to about 650 ° F. In this boiling range, the condensate contains a wide variety of hydrocarbon materials. Such materials may include compounds that make up fractions commonly referred to as naphtha, kerosene, diesel fuel (s), and gas oils (fuel oils, furnace oils, heating oils, etc.).

Atmospheric residue oils ("residues", "residues") obtained from conventional atmospheric thermal distillation towers can have a wide boiling range, especially when using mixtures of residues, but generally do not boil from about 600 ° F. Only entities that do not will be in the boiling range to the remaining boiling end point. These residual oils are mainly composed of gas oil components boiling in the range of about 600 to about 1,000 ° F. and heavy fractions boiling in the temperature range from about 1,000 ° F. to the boiling end point where only non-boiling entities remain.

In contrast to atmospheric towers, vacuum assisted thermal distillation towers (vacuum towers) typically separate the gas oil components from the relevant heavy fractions described above to free the gas oil fraction for separate recovery and other uses.

The olefins manufacturing industry is currently a fraction of crude oil or condensate (gaseous and / or liquid) as the main feed for the cracking furnace to use the entire crude oil, crude residue and / or the condensate itself as a significant portion of the feed. It is going beyond the use of more.

Recently, US Pat. No. 6,743,961 (hereinafter referred to as “USP 961”) was granted to Donald H. Powers. This patent relates to cracking whole crude oil by using vaporization / mild cracking zones containing packing. This zone is operated in such a way that the liquid phase of the whole crude oil, which has not yet been vaporized, remains in the zone until the cracking / vaporization of the more sticky hydrocarbon liquid component is maximized. This makes it possible to minimize the formation of solid residues which subsequently remain as deposits on the packing. This residue is then burned off the packing by conventional steam air decoking, ideally during a normal furnace decoking cycle (see column 7, lines 50-58 of the above-mentioned US patent). . Thus, the second zone 9 of the patent acts as a trap for the components of the crude oil feed which cannot be cracked or vaporized under the conditions used in the process, including hydrocarbonaceous materials (column 8, line of the above patent) 60-64).

U.S. Pat.No. 7,019,187 to Donald H. Powers relates to the process described in USP '961, but does not cover the full functionality of the vaporization / mild cracking unit, vaporizing (without leading mild cracking)-mild cracking (after vaporizing) spectrum. A weakly acidic cracking catalyst is used to further guide towards the mild cracking endpoint of.

US Pat. No. 7,404,889 to Donald H. Powers relates to the process described in USP '961, but uses atmospheric residue as the main liquid hydrocarbon feed for gasification units and furnaces.

The disclosures of the foregoing patents are incorporated herein by reference in their entirety.

US patent application Ser. No. 11 / 365,212, filed March 1, 2006, having the same inventor and assignee as USP '961, relates to the use of condensate as a hydrocarbon feed of the main liquid for vaporization units and furnaces. It is about.

United States Patent Application Publication No. 2007/0066860, issued to John S. Buchanan et al. On March 22, 2007, describes a crude oil having a high total acid number (TAN) using a flash drum unit in combination with a thermal cracking furnace. Thermal cracking of is disclosed. The publication discloses that the flash drum is only effective for the physical separation of two phases (gas and liquid) entering the drum. That is, it is disclosed that the composition of the gas phase exiting the flash drum is substantially the same as the composition of the gas phase flowing into the drum. Similarly, the composition of the liquid phase exiting the same flash drum is disclosed to be substantially the same as the composition of the liquid phase entering the drum. Preferred high TAN feeds are disclosed as crude oil or feed streams that are pre-refined to remove resid. Thus, Buchanan et al teach to eliminate the use of residues in this process.

In the publication to Buchanan et al., Naphthalic acid, which is also present in high TAN feeds, is substantially converted to CO, CO ₂ , and low molecular weight acids such as formic acid, acetic acid, propionic acid, and butyric acid.

Organic acids, including naphthalene acids, are present in increasing range in hydrocarbon feeds such as crude oil and are also a problem in crude oil refinery processors. Such naphthalene acids are often excluded from consideration, especially because of their corrosiveness.

In most refiners, above 400 ° F, crude oil cannot be processed with a total acid value (TAN) of greater than 1.0 due to the high corrosion properties of acids, especially naphthalene acids. As more global hydrocarbon production capacity is required to meet these requirements, the use of acid-containing feeds, especially crude oil, is required to meet the growth of global requirements.

According to the invention, organic acid-containing feeds such as whole crude oil and condensate and organic acid-containing fractions of crude oil, for example residues, are treated in combination with a vaporization unit and at least one thermal cracking furnace to reduce the initial acid content ( Conversion or deformation) as well as forming additional thermal cracking feeds from these feeds.

Herein, the organic acid content originally present in such a feed by the cracking action is processed by treating the organic acid containing feed using a vaporization unit in combination with at least one thermal cracking furnace to form additional cracking feed by the vaporization unit. Provide a unique process to reduce.

As used herein, the terms "hydrocarbon", "hydrocarbons" and "hydrocarbons" do not mean purely or simply materials containing hydrogen and carbon atoms. This term substantially includes hydrocarbonaceous materials which consist primarily or essentially of hydrogen and carbon atoms but may even contain significant amounts of other components such as oxygen, sulfur, nitrogen, metals, inorganic salts and the like. These terms include crude oil itself or fractions thereof such as gas oil, resid oil. These terms also include natural gas condensate.

As used herein, the term " gaseous " means one or more gases that are essentially vapor, such as steam alone, a mixture of steam and hydrocarbon vapors, and the like.

Coke as used herein refers to high molecular weight carbonaceous solids and includes compounds formed from condensation of multinuclear aromatics.

Olefin production equipment useful in the present invention will initially contain a feed and also include a pyrolysis (thermal cracking) furnace for thermal cracking. Pyrolysis furnaces for steam cracking of hydrocarbons are heated by convection and radiation and comprise a series of preheating, circulation and cracking tubes, generally such bundles of tubes, for preheating, conveying and cracking hydrocarbon feeds. High cracking heat is supplied by a burner disposed in the radiant section of the furnace (sometimes referred to as the "copy section"). Waste gas from such burners circulates through the convection section of the furnace, providing the heat necessary to preheat the hydrocarbon feed introduced. The convection and radiative sections of the furnace are joined at a "cross-over" and the tube described above transfers the hydrocarbon feed from the inside of one section to the inside of the next section.

In a typical furnace, the convection section may include a number of sub zones. For example, the feed is initially preheated in the first upper subzone, the boiler feed water is heated in the second subzone, the mixed feed and steam are heated in the third subzone, and the steam is fourth Superheated in the subzone, and the final feed / vapor mixture can be divided into a plurality of substreams and preheated in the bottom (bottom) or fifth subzone. The number of subzones and their function can vary considerably. Each subzone can have a number of conduits through which the furnace feed is conveyed, many of which are sinusoidal in shape. The convection section operates at much less severe operating conditions than the radiant section.

Cracking furnaces are designed for rapid heating in radiant sections starting at radiant tube (coil) inlets with low reaction rate constants due to low temperatures. Most of the heat transferred merely raises the hydrocarbons from the inlet temperature to the reaction temperature. In the middle of the coil, the rate of temperature rise is low but the cracking rate is significant. At the coil outlet, the rate of temperature rise is somewhat increased but not as fast as at the inlet. The rate of extinction of the reactant is the product of its reaction rate constant and its local concentration. At the coil end, the reaction concentration is low and further cracking may occur by increasing the process gas temperature.

Vapor dilution of the feed hydrocarbons lowers the hydrocarbon partial pressure, enhances olefin formation, and reduces any tendency to coke formation in the radiant tube.

Cracking furnaces generally have a rectangular firebox with an upright tube centered between radiant fire resistant walls. The tubes are supported from their tops.

Ignition of the radiant section is carried out with a burner or a combination of both installed on the wall or floor using gaseous or combined gas / liquid fuel. The firebox is usually placed under a slight negative pressure and most often has an upward flow of flue gas. Flue gas flow into the convection section is achieved by at least one of a natural draft or an induced draft fan.

The radiant coil is usually suspended on a single side below the center of the firebox. It may be located on a single side, or may be placed in parallel in a two-row tube arrangement that is crossed. Heat transfer from the burner to the radiation tube is usually caused by radiation and is thus a "radiative section" where the hydrocarbons are heated from about 1,400 ° F. to about 1,550 ° F., resulting in extreme cracking and coke formation.

The initial empty radiant coil is a tubular chemical reactor ignited accordingly. The hydrocarbon feed to the furnace is preheated from about 900 ° F. to about 1,000 ° F. in the convection section by convective heating from flue gas from the radiant section, steam dilution of the feed in the convection section, and the like. After preheating, in a conventional commercial furnace, the feed is ready to enter the radiant section.

Cracked gaseous hydrocarbons exiting the radiant section are rapidly reduced in temperature, preventing breakage of the cracking pattern. The cooling of the cracked gas prior to the same downstream further process in the olefin production plant recovers large amounts of energy as a high pressure stream for reuse in the furnace and / or olefin plant. This is often accomplished using transfer-line exchangers known in the art.

Liquid hydrocarbon feedstock downstream processes generally use oil quenching of furnace emissions after heat exchange in the same conveying line exchanger described above, although this may vary from plant to plant. The cracked hydrocarbon stream is then fractionated primarily to remove heavy liquids and then to squeeze uncondensed hydrocarbons to remove acid gases and water therefrom. The various desired products are then separated separately, for example into ethylene, propylene, a mixture of hydrocarbons having four carbon atoms per molecule, fuel oil, pyrolysis gasoline and a high purity hydrogen stream.

1 illustrates one vaporization / cracking system useful for the process herein.

1 shows a vaporization / cracking system capable of operating in an organic acid comprising as a main (primary) feed the fractions of the whole crude oil, including the whole crude oil, condensate, residues, in particular atmospheric residues, and mixtures thereof. .

In Fig. 1, as described above, since the actual furnace has a complicated structure, it is very outlined for simplicity and brevity.

The total acid value, or TAN, is a measure of the organic acid content of hydrocarbon materials. Such organic acids include, but are not limited to naphthalic acid.

TAN uses milligrams (mg) KOH / kg (kg) units of hydrocarbonaceous material to be determined and tested by ASTM method D-644. For simplicity, the following measurement methods and units are not repeated.

Organic acid-containing feed streams to which the present invention is applicable include any hydrocarbonaceous material, such as crude oil itself, residue oil, in particular one or more fractions of crude oil containing atmospheric residue oil, natural gas condensate and mixtures of two or more thereof. It includes.

The carboxylic acid species is the most corrosive acid grade present in the above feed streams. Within these carboxylic acid grades, the subgroups of naphthalene acids are most corrosive and problematic for the operation of cracking plants as a whole in terms of minimizing corrosion of the operating equipment.

As used herein, the atmospheric residue feed may be from a single or multiple sources and thus may be a single residual oil or a mixture of two or more residues. The atmospheric residual oils useful in the present invention may have a wide boiling range, especially if a mixture of residues is used, but generally the boiling end point at which the boiling range remains from about 600 ° F. to no boiling. Will be until.

The bottoms of the atmospheric residue oil from the atmospheric thermal distillation tower are heavy fractions boiling over a temperature range from the gas oil component boiling in the range of about 600 to about 1,000 ° F. and the boiling end point where only about 1,000 ° F. to the non-boiling entity remain. It is mainly composed.

Vacuum assisted thermal distillation towers (vacuum towers) typically separate the gas oil components from the relevant heavy fractions described above to provide residues of different compositions.

The amount of residues used in the feed 2 according to the invention can occupy a significant component of the total feed 2. The residue component may be at least about 20% by weight of the total weight of the feed (2), but is not necessarily within this range.

Depending on the specific physical and chemical properties of the residue added to the feed (2), other substances may be added to the feed. Such additive materials may include light gasoline, naphtha, natural gasoline and / or condensate. Naphtha can be used in the form of full range naphtha, hard naphtha, intermediate naphtha, heavy naphtha, or mixtures of two or more thereof. Light gasoline may have a boiling range from pentane (C5) to about 158 ° F. The full range naphtha, including hard, medium and heavy naphth fractions, may have a boiling range of about 158 to about 350 ° F. Boiling ranges for the hard, medium and heavy naphtha fractions may range from about 158 to about 212 ° F., about 212 to about 302 ° F, and about 302 to about 350 ° F., respectively.

Thus, the amount of hard material (s) intentionally added to the residue of the feed 2 can vary widely depending on the desire of the operator, while the residue of the feed 2, if present, is in line 10 And a substantial amount of feed 2 in feed vaporization unit 11.

In FIG. 1, the high TAN hydrocarbons primary feed 2 enters the upper feed preheating sub-zone 3 at the top and the cooler shows the liquid cracking furnace 1 touching the convection section of the furnace 1. The steam 6 is also superheated in the upper level of the convection section of the furnace.

The preheated cracking feed stream is then transferred to the vaporization unit 11 by a pipe (line) 10 (see USP '961 in full), which unit is the upper vaporization zone 12 and the lower vaporization zone 13. Separated by. This unit 11 mainly (predominantly) vaporizes at least a substantial portion of the naphtha and gasoline boiling ranges and hard materials remaining in the liquid state after the preheating step (3).

The gaseous material associated with the preheated feed received by the unit 11, and further gaseous material, hydrocarbons and acids, which are formed under certain conditions and prevail in the zone 12, are both zoned by line 14. 12) is removed from. Thus, line 14 may carry essentially all light hydrocarbon vapors, eg, the naphtha and gasoline boiling ranges and light ones present in zone 12 to carry some gaseous acid species. Liquid distillate present in zone 12 with or without some liquid gasoline and / or naphtha is removed therefrom via line 15 and moved into the upper interior of lower zone 13.

In this embodiment, the zone 12 and zone 13 are separated from the fluid communication with each other by an impermeable wall 16, which may be a solid tray. Line 15 represents external fluid downflow communication between zone 12 and zone 13. Alternatively, or in addition, the wall 16 may be at least partially liquid permeable by using one or more trays configured to allow the liquid to move downward into the interior of the zone 13 and allow vapor to rise into the interior of the zone 12. Zone 12 and zone 13 can be in internal fluid communication therebetween. For example, instead of the impermeable wall 16, if a liquid in the unit 11 flows internally into the section 13 instead of flowing out of the unit 11 via the line 15, a chimney tray ( chimney trays may be used. In this way, when flowing down internally, the dispenser 18 is optional.

Either way, the liquid can move downward into zone 13 so that the liquid can be removed from zone 12 into zone 13 and thus encounter one or more liquid dispensing device 18. The device 18 will evenly distribute the liquid across the cross section of the unit 11 so that the liquid will flow evenly across the width of the tower and come into contact with the packing 19.

The steam 6 moves through the superheated subzone 20 and then through the line 21 to the bottom 22 of the zone 13 below the packing 19. In the packing 19, the liquid and the vapor from the line 21 are intimately mixed with each other to vaporize a portion of the liquid 15. This newly formed hydrocarbon vapor, along with the vapor 21, is removed from the zone 13 via line 17 and added to the vapor in line 14 to produce a combined hydrocarbon vapor product in line 25. Form. Stream 25 may essentially contain hydrocarbon vapors from feed 2, for example gasoline, naphtha, middle distillate, gas oil and steam.

Thus, stream 17 represents the portion of feed stream 2 and the dilution vapor 21 subtracted the hydrocarbon liquid residue from feed 2 present in bottom stream 26. Stream 25 comprises the kind of organic acid present in the first feed 2. Stream 25 passes through a header (not shown) that divides this stream 25 into a number of sub-streams, and passes through a number of conduits (not shown) to convection section preheating sub-zone of furnace 1 ( 27) Move in. Section 27 is the lower and hotter section of the furnace 1. Section 27 is used to preheat stream 25 to a temperature suitable for cracking in the radiant zone 29 as described above.

After substantial heating in section 27, stream 25 comprising organic acid species is transferred into radiant section 29 by line 28. Also, in general, a number of individual streams from and to the sub-zones 27 through 29 are represented as a single flow stream 28 for simplicity.

In the radiant fire chamber 29 of the furnace 1, the feed from the line 28 containing a plurality of various hydrocarbon components is subjected to the extreme thermal cracking conditions as described above. These cracking conditions convert or otherwise modify the significant, even overwhelmingly large amount of nathalenic acid present in carbon monoxide (CO), carbon dioxide (CO ₂ ), and starch molecular weight acids (formic acid, acetic acid, propionic acid and butyric acid). Let's do it.

The cracked product exits the radiation chamber 29 by line 30 for further treatment in the residue downstream of the olefin plant of furnace 1 as indicated in USP '961 and described above.

When using crude oil, condensate, residues and the like as significant component (s) of feed (2), a substantial amount of distillate containing organic acids ultimately results in unit (1), in particular in zone (13) It is vaporized, moved into the furnace 1 and cracked, thus converting this distillate into a light component.

The feed 2 enters the furnace 1 at a pressure slightly higher than normal pressure to about 100 psig (hereinafter referred to as "normal pressure to 100 psig") at a temperature near the ambient temperature to about 300 ° F.

Feed 2 may enter zone 12 through line 10 at a temperature between ambient pressure and 100 psig, at a temperature near ambient temperature to about 750 ° F., for example between about 500 and about 750 ° F.

Stream 14 may be essentially all hydrocarbon vapors formed from feed 2 and is also at a temperature near ambient temperature to about 700 ° F. at a pressure of from normal pressure to 100 psig. This stream 14 may or may not comprise a portion of the acid crude present initially in the feed 2.

Stream 15 may be essentially any residual liquid from feed 2, minus vaporized in preheater 3 and zone 12, and may also be at pressures slightly higher than atmospheric to about 100 psig (hereinafter “normal pressure”). To 100 psig ") at a temperature near ambient temperature to about 700 ° F.

Zone 12 may be used as a physical separation zone, similar to the flash drum of the publication to Buchanan et al., As described above, and may also contain additional symbols of liquid hydrocarbons introduced into zone 12 by line 10. Can be operated in the conditions used to cause it.

Zone 13 is operated at a temperature of about 700 to about 1,100 ° F., thereby forming a significant amount of additional gaseous hydrocarbons from the liquid and receiving from zone 12 by line 15.

Thus, the vaporization unit 11 forms a considerable amount of additional gaseous hydrocarbons from the liquid present in the preheated feed stream 10 in addition to vaporizing the organic acid present in the original feed 2.

Therefore, the chemical composition of the gaseous phase leaving unit 11 by lines 14 and 17 is substantially different from the chemical composition of the gaseous phase flowing into unit 11 by line 10. Similarly, the chemical composition of the liquid phase exiting unit 11 by line 26 is substantially different from the chemical composition of the liquid phase entering unit 11 by line 10. In other words, the unit 11 does not only effect the physical separation of the two phases (liquid and gaseous phase) entering the unit 11 by the line 10.

The combination of stream 14 and stream 17 as represented by stream 25 may be at a temperature of about 600 to about 800 ° F. at a pressure of from normal pressure to 100 psig, for example from about 0.1 to about vapor per pound of hydrocarbon. It contains about 2 pounds, preferably about 0.1 to about 1 pound of total steam / hydrocarbon consumption.

In zone 13, the dilution ratio (hot gas / liquid load) will vary widely because the composition of crude oil, fractions of crude oil (particularly residues) and condensate varies widely. In general, at the top of zone 13, hot gases such as steam and hydrocarbons may be present in a ratio of steam to hydrocarbons of about 0.1 / 1 to about 5/1.

Vapor is an example of a suitable hot gas introduced by line 21. Stream 6 may be a type of steam commonly used in conventional cracking plants. Other materials may be present in the steam used. All these gases are preferably at a temperature sufficient to volatilize a substantial fraction of the liquid hydrocarbon 15 entering the zone 13. In general, the gas inlet zone 13 from conduit 21 will be at least about 650 ° F., preferably from about 900 to about 1,20 ° F., at ambient pressure to 100 psig. Such gases will be referred to hereinafter only as steam for the sake of simplicity.

Thus, stream 17 may be a mixture of vapor, acid species, and hydrocarbon gas having a boiling point lower than about 1,10O <0> F. Stream 17 may be at a temperature of about 600 to about 800 ° F. at a pressure of normal to 100 psig.

The vapor from line 21 does not act only as a diluent for partial pressure purposes as is usual in cracking operations. Rather, the vapor from line 21 not only provides a dilution function but also provides additional vaporization and mild cracking energy for hydrocarbons remaining in the liquid state in unit 11. This is done with only enough energy to achieve vaporization and / or mild cracking of the heavy hydrocarbon components as found in the whole crude oil and residues. For example, by using steam in line 21, substantial vaporization / mild cracking of the feed 2 liquid is achieved. Thereby, very high vapor dilution ratios and the highest temperature steams are provided, where most of them require the liquid hydrocarbon load to gradually move down in zone (13).

In accordance with the present invention, hydrocarbon and acid species that boil lighter (lower) than about 1,100 ° F., which remain in the feed 10 of FIG. 1, as described above, are all in the unit 11, as described above. It will be vaporized and removed by line 14 or line 17 or by both lines and enter the furnace 1. Further, hydrocarbon-based entities that are heavier than the hard entities described above in the paragraph are mildly cracked or otherwise decomposed into light hydrocarbon-based entities as described above in unit 11, The hard entity thus formed is removed by line 17 as an additional feed to the furnace 1. Liquid residue in feed 10, if present, is removed by line 26 for arrangement elsewhere.

Example

Doba atmospheric residue having a TAN value of 4.5 was mixed with light gasoline and naphtha in equal parts by weight to form a mixture with a TAN value of 2.25. This mixture was introduced into the preheating section 3 of the convection section of the pyrolysis furnace 1. This feed mixture 2 is at 260 ° F. and 80 psig. In this convection section, the feed 2 is preheated to about 690 ° F. at about 60 psig and then sent through the line 10 into the vaporization unit 11 and at about 690 ° F. and 60 psig, gasoline, naphtha and The mixture of gas oil gas was separated in zone 12 of the unit.

This separated gas was removed from zone 12 into the convection preheating subzone 27 of the same furnace for delivery by line 25.

The remaining hydrocarbon liquid from the residue-based feed 2 is transported to the lower section 13 by line 15 and then separated downward from the lower section to its bottom after separation from the aforementioned companion hydrocarbon gas. It was possible.

Steam 21 preheated at about 1,050 ° F. was introduced near the bottom of vaporization zone 13 such that the vapor to hydrocarbon ratio in the lower section 13 was about one. The falling liquid load flowed back against the vapor rising from the bottom of the zone 13 to the top thereof. For the liquid falling down in zone 13, the vapor to liquid hydrocarbon ratio increased from the top of section 19 to the bottom.

The mixture of vapor and hydrocarbon gas 17 at about 750 ° F. is withdrawn from near the top of zone 13 and mixed with the gas removed early from zone 12 via line 14, thereby producing about about one pound of hydrocarbon present. A complex vapor / hydrocarbon gas stream 25 comprising 0.5 pounds of steam was formed. This composite stream was preheated from less than about 50 psig to about 1,000 ° F. in sub-zone 27 and then sent into radiant chamber sub-zone 29 to crack at temperatures ranging from 1,400 ° F. to 1,550 ° F. Due to the conversion of naphthalic acid present in stream 25, the cracking furnace increased CO and CO ₂ production.

The bottom product 26 of unit 11 was removed at a temperature of about 900 ° F. and a pressure of about 60 psig and sent to the downstream treatment equipment for the desired further treatment.

A significant amount of organic acid, including naphthalene acid, was terminated in stream 25 and then converted to CO, CO ₂ and low molecular weight acids in the cracking furnace.

At the same time, additional gas feed for the cracking furnace was formed by vaporizing the amount of liquid feed added by the operation of the vaporization unit 11, in particular the vaporization zone 13.

Claims (10)

A method of thermal cracking a hydrocarbon feedstock consisting of at least one hydrocarbon material, the at least one hydrocarbon material comprising at least one organic acid species,
The method comprises:
Preheating the feedstock to form a preheated stream comprising an initial gas phase having an initial chemical composition and an initial liquid phase having an initial chemical composition,
Sending the preheated stream to a vaporization step, wherein a portion of the initial liquid phase is such that the chemical composition of the total gas exiting the vaporization step is different from the initial chemical composition of the initial vapor phase and the remainder exiting the vaporization step. Vaporizing the chemical composition of the liquid to be different from the initial chemical composition of the initial liquid phase, and
Sending at least a portion of said gas exiting said vaporization step to said at least one thermal cracking furnace as a feed to at least one thermal cracking furnace. The method of claim 1,
Wherein said hydrocarbon feedstock has a TAN of at least 1.0 mg KOH / g feedstock g. The method of claim 1,
Wherein said hydrocarbon feedstock has a TAN of at least 0.5 mg KOH / g feedstock g. The method of claim 1,
Wherein said hydrocarbon feedstock is at least one of whole crude oil, condensate, residues, and mixtures of two or more thereof. The method of claim 1,
Wherein said hydrocarbon feedstock is at least one atmospheric residue. The method of claim 1,
Wherein said at least one organic acid species comprises at least one carboxylic acid species. The method according to claim 6,
Wherein said carboxylic acid species comprises at least one naphthalene acid species. The method of claim 1,
The vaporization step uses at least a first vaporization zone and a second vaporization zone,
The first vaporization zone receives the preheated feedstock comprising the initial gas phase and the initial liquid phase and at least separates the initial gas phase from the initial liquid phase,
The separated initial gaseous material is sent from the first vaporization zone as a feed to the at least one thermal cracking furnace,
The second vaporization zone receives a preheated initial liquid material that is not present as a gas in the first vaporization zone from the first vaporization zone, and also the preheated in this second vaporization zone in the second vaporization zone. At least one of heating and mild cracking is applied to the preheated initial liquid material and the remaining liquid comes out until a substantial amount of the initial liquid material is vaporized to form additional gaseous material,
The additional gaseous material formed in the second vaporization zone is removed therefrom and sent as a feed to at least one thermal cracking furnace, whereby the chemical composition of the additional gaseous material formed in the second vaporization zone is And wherein the chemical composition of the remaining liquid exiting the second vaporization zone is different from the chemical composition of the initial gas phase and is different from the chemical composition of the initial liquid phase. The method of claim 8,
Wherein the initial liquid material of the second vaporization zone is subjected to a temperature in the range of 700 to 1,100 ° F. The method of claim 8,
The initial gaseous material separated from the first vaporization zone and the additional gaseous material removed from the second vaporization zone are combined and the combined stream is sent to at least one thermal cracking furnace for thermal cracking of hydrocarbon feedstock. .

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