MXPA98004989A - Hidro fractioning of heavy hydrocarbons with control of aromatic substances pola - Google Patents

Abstract

A process for hydrofractioning a heavy hydrocarbon petroleum feedstock is described, a substantial portion of which boils above 524 ° C, which process includes the steps of: (a) passing a feed suspension of a mixture of matter oil premium of heavy hydrocarbons and from approximately 0.01-4.0% by weight (based on fresh raw material) of additive particles that inhibit coke upwards, through a confined vertical hydrofraction zone, the hydrofraction zone is maintained at a temperature between approximately 350øy 050øC and a pressure of at least 3.5 MPa and a space velocity of up to 4 volumes of hydrocarbon oil per hour per volume of hydrofraction zone capacity, (b) remove from the top of the hydrofraction zone a mixed effluent containing a gaseous phase comprising hydrogen and hydrocarbons in vapor form and a phase liquid consisting of heavy hydrocarbons, (c) passing the mixed effluent in a hot separating vessel, (d) extracting from the upper part of the separator a gaseous stream consisting of hydrogen and hydrocarbons in the form of vapor, (e) extracting from the bottom of the separator a liquid stream consisting of heavy hydrocarbons and particles of additives that inhibit coke, and (f) fractionating the separated liquid stream to obtain a heavy hydrocarbon stream which boils at a temperature higher than 450øC, the heavy hydrocarbon stream It contains additive particles and a light petroleum product. According to the novel feature, at least part of the fractionated heavy hydrocarbon stream that boils at a temperature above 450 ° C is reused to form part of the hydrocarbon-heavy petroleum feedstock to an aromatic petroleum of lesser polarity that is added to the heavy hydrocarbon petroleum raw material so that a high proportion of aromatic substances of lower polarity with respect to asphaltenes is maintained during hydroprocessing. This provides excellent yields without coq formation

Description

HIDRORAACGIC NUMBER OF HEAVY HYDROCARBONS CONTROLLED BY POLAR AROMATIC SUBSTANCES TECHNICAL FIELD This invention relates to the treatment of hydrocarbon oils and, more particularly, to the hydroconversion of heavy hydrocarbon oils in the presence of additives, such as iron and / or carbon additives.

ANTECEDENTS OF THE TECHNIQUE Hydroconversion processes for the conversion of heavy hydrocarbon oils to light oils and good quality intermediate naphtha to produce raw materials, fuel oil and diesel are well known. These heavy hydrocarbon oils can be materials such as crude oil, atmospheric tar waste products, vacuum tar residue products, heavy cycle oils, oil shale oils, coal derived liquids, crude oil residue, petroleum oils, petroleum crude oil from primary distillation and heavy bituminous oils extracted from oil sands. Of particular interest are the oils extracted from oil sands REF: 27708 and which contain materials with a wide boiling range from naphthas to kerosene, gas oil, tar, etc., and which contains a large portion of material that boils at a temperature higher than 524 ° C equivalent to the atmospheric boiling point. As the reserves of conventional crude oils decline, these heavy oils must be improved to meet the demands. In this improvement, the heavier materials are converted to lighter fractions and most of the sulfur, nitrogen and metals must be removed. This can be carried out either by a coking process such as delayed or fluidized coking, or by a hydrogen addition process such as thermal or catalytic hydrofraction. The distillate yield of the coking process is typically about 80% by weight, and this process also provides substantial amounts of coke as a by-product. Work has also been done on the alternative processing route involving the addition of hydrogen at high pressures and temperatures and this has been found to be very promising. In this process, hydrogen and heavy oil are pumped up through an empty tubular reactor in the absence of any catalyst. It has been found that the high molecular weight compounds are hydrogenated and / or hydrofractioned at lower boiling ranges. Simultaneous reactions of desulfurization, demetallization and denitrogenation take place. Reaction pressures of up to 24 MPa and temperatures of up to 490 ° C have been used. Work has been done to develop additives which suppress the coking reaction or can remove the coke from the reactor. It has been shown in Ternan et al., Canadian Patent No. 1,073,389, issued March 10, 1980, and Ranganathan et al., United States Patent No. 4,214,977, issued July 29, 1980, that the addition of carbon or additive based on carbon results in a reduction in the deposition of coke during hydrofractionation. The carbon additives act as sites for the deposition of coke precursors and therefore provide a mechanism for their removal from the system. Ternan et al. , Canadian Patent No. 1,077,917 discloses a process for the hydroconversion of a heavy hydrocarbonaceous oil in the presence of a catalyst prepared in situ from trace amounts of metals added to petroleum as petroleum-soluble metal compounds.

US Pat. No. 3,775,286 discloses a process for hydrogenating coal in which the coal is impregnated with hydrated iron oxide or with dry hydrous iron oxide powder which is physically mixed with the pulverized coal. Canadian Patent No. 1,202,588 describes a process for hydrofractioning heavy oils in the presence of an additive in the form of a dry mixture of carbon and an iron salt, such as iron sulfate. The development of such additives has allowed the reduction of the operating pressure of the reactor without coking reaction. However, the injection of large amounts of fine additive is expensive and the application is limited by the incipient coking temperature, at which point mesof se (pre-coke material) is formed in increasing amounts. Furthermore, it has been demonstrated in Jain et al., U.S. Patent No. 4,969,988, that the conversion can be further increased through the reduction of gas retained by injecting an antifoaming agent, preferably into the upper section of the reactor. Sears et al. , U.S. Patent No. 5,374,348 describe the reuse or recycling of waste from the heavy vacuum fractionator to the reactor to reduce the total additive consumption by 40% more.

It is an object of the present invention to provide a process for hydrofracting heavy hydrocarbon oils that use additive particles in the raw material to suppress coke formation in which improved yields can be obtained by controlling the proportion of aromatic substances of minor polarity with respect to the asphaltenes in the reactor and in this way inhibit the formation of coke.

DESCRIPTION OF THE INVENTION In accordance with the present invention, it has been discovered that further improvements are obtained in the hydroprocessing of heavy hydrocarbon oils containing additive particles to suppress coke formation by adding aromatic oils, preferably in the form of a recycled process derived from heavy gas oil, to the hydroprocessing raw material so that a high proportion of aromatic substances of lower polarity with respect to asphaltenes is maintained during the hydroprocessing and also recycling of a heavy product hydropilled downstream (pitch) to the hydroprocessing raw material. Therefore, the present invention, in one aspect, relates to a process for hydrofractioning heavy hydrocarbon petroleum feedstock, a substantial portion of which boils at a temperature greater than 524 ° C, which comprises: passing a feed of suspension of a mixture of heavy hydrocarbon petroleum feedstock and approximately 0.01-4.0% by weight (based on the fresh raw material) of additive particles that inhibit coke, comprising particles of an iron compound having smaller sizes of 45 μm upwards, through the confined vertical hydrofraction zone, the hydrofraction zone is maintained at a temperature between approximately 350 ° and 600 ° C and a pressure of at least 3.5 MPa and a space velocity of up to 4 volumes of hydrocarbon oil per hour per volume of hydrofraction zone capacity. A mixed effluent containing a gaseous phase comprising hydrogen and hydrocarbons in vapor form, and a liquid phase consisting of heavy hydrocarbons is removed from the top of the hydrofraction zone and this mixed effluent is passed to a hot separator vessel. A gaseous stream comprising hydrogen and vapor hydrocarbons is extracted from the upper part of the separator, while from the lower part a liquid stream consisting of heavy hydrocarbons and particles of the additive which inhibits the coke is extracted. According to the novel feature, an aromatic oil is added to the heavy hydrocarbon petroleum raw material so that a high proportion of aromatic substances of a lower polarity is maintained with respect to asphaltenes during hydroprocessing, this aromatic petroleum is a diesel fraction heavy weight obtained during the fractionation of the lower liquid stream from the hot separator. In addition, iron particles are used in the absence of an active hydrogenation catalyst. Preferably, the liquid stream from the bottom of the separator is fractionated to obtain a heavy hydrocarbon stream (pitch) that boils at a temperature above 450 ° C, preferably above 495 ° C and that contains the additive particles, and a product of light oil. At least part of this fractional breach stream boils at a temperature above 450 ° C and contains additive particles that are reused to form part of the heavy hydrocarbon petroleum feedstock. The process of this invention is capable of processing a wide range of heavy hydrocarbon feedstocks. Therefore, aromatic raw materials can be processed as well as raw materials which have traditionally been very difficult to hydroprocess, for example, vacuum residues fractionated by viscosities, waste materials challenged, asphalt out of specification, crushed (grunge) waste from oil storage tanks, etc. These difficult to process raw materials are characterized by low reactivity in the fractionation by viscosities, a high tendency to coke, a poor conversion in the hydrofractionation and difficulties in the distillation. In general, they have a low proportion of polar aromatic substances with respect to asphaltenes and little reactivity in the hydrofractionation in relation to the aromatic raw materials. Most of the raw materials contain asphaltenes to a greater or lesser degree. Asphaltenes are high molecular weight compounds that contain heteroatoms which impart polarity. It has been demonstrated by the model of Pfeiffer and Sal Phys. Chem. 139 (1940), that the asphaltenes are surrounded by a layer of resins, or polar aromatic substances which stabilize them in colloidal suspension. In the absence of polar aromatic substances, or if the polar aromatic substances are diluted by paraffinic molecules, these asphaltenes can self-associate, or flocculate to larger molecules which can be separated from the solution by precipitation. This is the first stage in coking.

In a normal hydrofraction process, there is a tendency for asphaltenes to become lighter materials, such as paraffins and aromatic substances. Polar aromatics also become lighter materials, but at a faster rate than asphaltenes. The result is that the proportion of polar aromatic substances decreases with respect to asphaltenes, and the proportion of paraffins with respect to aromatic substances increases as the reaction progresses. This eventually leads to asphaltene flocculation, mesophase formation and coking. This coking can be minimized by the use of an additive, and coking can also be controlled at the incipient coking temperature, which is the temperature at which coking begins for a fixed concentration of additive. This temperature is very low for poor supplies, resulting in little conversion. In the process of this invention, it is now possible to very successfully process raw materials that are traditionally very difficult to process. This is obtained by first reusing the fractional breach current that boils at a temperature above 450 ° C, with additive particles and secondly by adding a less polar aromatic oil to the raw material, the aromatic oil is in the form of a reused or recycled heavy gas oil from the same hydrofractioned. As indicated in the above, the asphaltenes in the raw material are surrounded by a cover of highly polar aromatic substances which are a problem in terms of coke formation. By increasing the conversion the polarity of the aromatic cover around the asphaltene increases. However, according to this invention, by introducing aromatic substances of lower polarity into the reaction system, these aromatic substances of lower polarity are able to surround and mix with, and dilute the highly polar aromatic substances. This also tends to reduce the polar gradient so that it allows hydrogen to pass through the jacket and allows the olefinic fragments to be removed by diffusion and prevents recombination. This allows time for the asphaltene to decompose in the process. As used herein, the term "lower polarity aromatic substances" means aromatic oils of. lower polarity in relation to the polarity of components such as asphaltenes in the raw material of heavy hydrocarbons. Therefore, by controlling the highly polar aromatic substances in the reaction system according to this invention, an equilibrium is maintained so that "asphaltenes" see "the aromatic substances including those of minor polarity anywhere. The paraffins that form are diluted and can diffuse rapidly in this continuum. As also explained in the above, any limitation of mass transfer that has previously been caused by the highly polar aromatic cover is minimized, and the dispersion of the olefins in the aromatic substances of lower polarity decreases the recombination reactions and decreases the probability of recombination with asphaltenes. The non-aromatic fragments formed from the asphite are diffused away from the asphaltene nucleus and prevent the growth of molecular weight by recombination. By matching the polar aromatic substances through the addition of additional aromatic substances, the reactivity of the pitch is maintained and the coking tendency is reduced. The pitch can be reused under these conditions, which results in an increase in conversion. This reduces the molecular weight of the pitch which further stabilizes the operation at a high total conversion. It has been expected that this extensive reuse can have a serious effect on reactor productivity, but it has been found that this effect on productivity is more than compensated for by the high reactor temperatures that become possible. Apparently there are no compounds that intrinsically form coke, only limitations imposed by the colloidal system and by mass transfer in the system. Furthermore, it is evident that there is no incipient intrinsic temperature of coking for each raw material, only the need to suspend the additive, and suspend and transport the asphaltenes until they are converted or leave the reactor. There is an additional benefit of high conversion that is not immediately apparent. The liquid traffic in the reactor, which is composed of tar and aromatic petroleum of low polarity, is reduced in large quantity. This can be controlled by reuse, and in such a way that the reactor additive can be greatly increased each time an operation is carried out. This allows the process to be much more stable as an increasing surface area of additive is available to aid in the transfer of hydrogen to the olefins and aromatics generated.

BEST WAYS ™ = * T.T.T ^ T R CAGE THE INVENTION The process of this invention can be carried out under very moderate pressure, preferably in the range of 3.5 to 24 MPa, without coke formation, in the hydrofraction zone. The temperature of the reactor is typically in the range of 350 ° to 600 ° C, with a temperature of 400 ° to 500 ° C being preferred. The LHSV is typically less than 4 h "1 on a fresh supply basis, with a range of 0.1 to 3 h" 1 being preferred, and a range of 0.3 to 1 h "1 is particularly preferred. One important advantage of this invention is that the process can be operated at a higher temperature and a lower hydrogen partial pressure compared to a usual process for the fractionation of heavy oils.This higher temperature provides a better balance between thermal decomposition of asphaltene and aromatic saturation and thermal decomposition. Lower partial pressures of hydrogen lead to efficiencies in the handling of hydrogen and a reduced capital in operating costs of the equipment, although the hydrofraction can be carried out in several known reactors of upward or downward flow, it is particularly suitable for a tubular reactor. through which the feed and gas move upwards, the effluent from the top r is separated in a hot separator and gaseous streams from the hot separator can be fed to a low temperature, high pressure separator where they are separated into a gaseous stream containing hydrogen and smaller amounts of gaseous hydrocarbons, and a stream of liquid product It contains light oil product. Various aggregate particles can be used in the process of the invention, provided that these particles are capable of resisting the hydrofraction process and remain effective as part of the reuse. Particularly useful additive particles are those described in Belinko et al., U.S. Patent No. 4,963,247, issued October 16, 1990. Thus, the particles are typically an iron compound, preferably ferrous sulfate having smaller particle sizes than 45 μm and with a larger portion, ie, at least 50% by weight, preferably having particle sizes of less than 10 μm. According to a preferred embodiment, the iron sulphate particles are mixed with a heavy hydrocarbon petroleum feed and pumped along with hydrogen through the vertical reactor. The liquid-gas mixture from the top of the hydrofraction zone can be separated in many different ways. One possibility is to separate the mixture from the liquid-gas in a hot separator which is maintained at a temperature in the range of about 200 ° / 470 ° C and at the hydrofraction reaction pressure. A portion of the heavy hydrocarbon petroleum product of the hot separator is used to form the reuse stream of the present invention after the secondary treatment. Therefore, the portion of the heavy hydrocarbon petroleum product of the hot separator that is used for recycling is fractionated in a distillation column in which a heavy liquid or pitch stream is obtained. This pitch stream boils at a temperature above 495 ° C with a pitch boiling at a temperature above 524 ° C with particular preference. This pitch stream is then reused again to form part of the feed suspension to the hydrofraction zone. Part of this pitch stream is also constituted by a pitch product which can be fed to a thermal fractionation process. A fraction of aromatic gas oil which preferably boils at a temperature higher than 400 ° C is also removed from the distillation column, and this is reused again to form part of the raw material for the hydrofractionation zone for the purpose of controlling the proportion of polar aromatic substances with respect to asphaltenes. Preferably, the heavy oil stream reused constitutes in the range of about 5 to 15% by weight of the raw material of the hydrofraction zone, while the aromatic petroleum, for example, the reused aromatic gas oil, constitutes in the range of 15 to 50% by weight of the raw material, based on raw material structures. The gaseous stream from the hot separator containing a mixture of hydrocarbon and hydrogen gases is further cooled and separated in a high pressure, low temperature separator. When using this type of separator, the resulting gaseous output stream contains mostly hydrogen with some impurities such as hydrogen sulfide and light hydrocarbon gases. This gaseous stream is passed through a scrubber and the purified hydrogen can be reused as part of the hydrogen supply to the hydrofraction process. The purity of the hydrogen gas is maintained by adjusting the conditions of the scrubber and by adding accumulated hydrogen. The liquid stream of the high pressure and low temperature separator represents a light hydrocarbon petroleum product of the present invention and may be sent for secondary treatment. According to an alternative embodiment, the heavy oil product of the hot separator is fractionated into an upper light oil stream and a lower stream or waste stream comprising oil and heavy gas oil. A portion of this mixed waste stream is reused again as part of the raw material to the hydrofraction while the remainder of the waste stream is further separated into a stream of gas oil and a pitch product. The diesel oil stream is then reused to be a material, giving the hydrofractioner a bonus as an additional low polarity aromatic accumulator for polar aromatic control in the system. The process of the invention can convert heavy gas oil to its disposal and can also convert a very high proportion of heavy hydrocarbon materials from the raw material to liquid products that boil at a temperature below 400 ° C. These characteristics make the process useful as an outlet for surplus aromatic streams in a refinery. It is also uniquely useful as an outlet for raw waste materials. In addition, the process represents a unique method for the control of hydrofraction of heavy hydrocarbon oils by controlling the quantities and compositions of the pitch stream and the stream of aromatic petroleum fed as part of the raw material to the hydrofraction process. For some raw materials, it has been found to be advantageous to carry out the. treatment before hydrofraction to remove paraffinic material with a high boiling point.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference is made to the appended drawings in which: Figure 1 is a schematic flow diagram showing a typical hydrofraction process to which the present invention can be applied; Figure 2 is a graph of hydrogen in pitch vs. conversion; Figure 3 is a graph of hydrogen in pitch vs. conversion; Figure 4 is a graph of aspharyne in pitch vs. conversion; Figure 5 is a graph of asphaltene in the reactor products vs. conversion; Figure 6 is a graph of pitch quality vs. VG0 reuse cup; Figure 7 is a performance shift plot with reuse of VG0; Figure 8 is a graph of pitch conversion vs. LHSV of pitch; Figure 9 is a graph of TIOR / additive vs. additive concentration in the reactor; Figure 10 is a graph of coke performance vs. reuse of HVGO; Figure 11 is a graph of additive coke vs. molecular weight of pitch; and Figure 12 is a graph of quaternary carbon vs. polar aromatic phase / total aromatic phase.

DESCRIPTION OF THE PREFERRED MODALITIES In the hydrofraction process as shown in Figure 1, the iron salt additive is mixed together with a heavy hydrocarbon petroleum feed in a feed tank 10 to form a suspension. This suspension, which includes heavy oil or reuse pitch 39, is pumped by means of the feed pump 11 through an inlet pipe 12 to the bottom of an empty reactor 13. The reused hydrogen and accumulated hydrogen in line 30 are simultaneously fed into the reactor through line 12. A gas / liquid mixture is drawn from the top of the reactor, through line 14 and is introduced into a 15 hot separator. In the hot separator, the effluent from the tower 13 is separated in a gaseous stream 18 and a liquid stream 16. The liquid stream 16 is in the form of heavy oil, which is collected at point 17. The gaseous stream of separator 15 is transported via pipe 18 to a high temperature and low pressure separator 19. Within this separator the product is separated into a gaseous stream rich in hydrogen which is extracted through line 22, and a petroleum product which is extracted through line 20 and collected in 21. The current 22 rich in hydrogen is passed through a packed scrubbing tower 23, where it is purified by means of a scrubbing liquid 24 which is reused through the tower by means of a pump 25 and a reuse circuit 26 . The purified, hydrogen-rich stream emerges from the scrubber via a pipe 27 and is combined with fresh accumulated hydrogen added through line 28 and reused through reuse gas pump 29 and line 30 back to reactor 13. The heavy oil collected at 17 is used to provide heavy reuse oil of the invention and before being re-used again in the suspension feed, a portion is withdrawn via line 35 and fed to the fractionator 36 with an oil stream Residual or bottom heavy boiling at a temperature higher than 450 ° C, preferably higher than 524 ° C which is extracted by means of the pipe 39. This pipe connects the feed pump 11 to constitute part of the feed suspension to the container 13 of the reactor. Some of the heavy oil extracted from the residues of the fractionator 36 can also be collected as a pitch product. The fractionator 36 can also serve as a source of aromatic oil to be included in the raw material to the vessel 13 of the reactor. Therefore, a fraction 37 of heavy aromatic gas oil is removed from the fractionator 36 and fed into the inlet pipe 12 to the bottom of the reactor 13. This heavy gas oil stream preferably boils at a temperature above 400 ° C. A stream 38 of light oil is also drawn from the top of the fractionator 36 and forms part of the light oil product 21 of the invention.

DESCRIPTION OF THE PREFERRED MODALITIES Certain preferred embodiments of this invention are illustrated by the following non-limiting examples.

Example 1 (Comparative) Tests are carried out in a pilot hydrofraction plant of the type shown in Figure 1, using as raw material Cold Lake vacuum residues (CLVB), with 5.6% sulfur, 75% by weight of material 254 ° C + and 5th API. First, the CLVB is tested in a mode in which it passes only once, and a model is developed for this operation and a range of conditions. Then, the pilot plant is operated with reuse of pitch, and it is found that the rate constant for the reused material is: K = 0.953 - 0.0083 (conversion at 524 ° C +) where the conversion is one percent by weight. Therefore, the rate constant for fresh supply would be K = 0.953, and for the pitch product of a conversion operation of 80% at 524 ° C it would be K = 0.953 - 0.0083 (80) = 0.289. This is a significant decrease in reactivity for the following typical conditions in a pilot plant: Temperature, 447 ° C Feeding 80% fresh / 20% reused Pressure, 13.8 MPa Cutting point reuse, 480 ° C Gas regime 28 1 / min LHSV fresh feed, 0.48 Gas purity, 85% H2 Additive * 1.2% of total food Reactor with 2.54 cm ID by 222 cm high * The additive used is ferrous sulfate having particle sizes less than 45 μm, as described in U.S. Patent No. 4,963,247. This shows that the reused pitch is less reactive than the fresh feed, and that this reactivity depends on the conversion (reaction gravity) to which it has been subjected. These data discourage the reuse of pitch for conversion reasons, and seem to show that there is a portion of the food which inherently is not convertible, or is convertible only with difficulty. However, these tests show that the reused iron sulfide additive retains its activity, which is a strong incentive for the reuse of tar (reuse reduces the requirement for fresh additive up to 40% in the study).

Example 2 (Comparative) Fractionated vacuum residues are measured by viscosities of a commercial viscosity fractionator at the Petro-Canada Montreal refinery (a type of Shell rinser) in the same pilot plant as in example 1. The conditions for the sample test are as follows: Temperature 449 ° C Pressure 13.8 MPa Gas rate 28 1 / min Gas purity 85% H2 Fresh feed LHSV 0.5, feed source - Venezuela mix 24 Additive * 3% based on total feed * The additive used is ferrous sulfate having particle sizes less than 45 μm, as described in U.S. Patent No. 4,963,247. It is found that the conversion of pitch is '83%, and this is comparable to a conversion of 85% obtained with mixed vacuum residues 24 supplied under similar conditions. This test shows that the material fractionated by viscosities can operate at an affordable conversion with respect to the untreated material of the same boiling range. However, it is also shown that the quality of the pitch deteriorates with respect to the hydrogen and nitrogen content (Figures 2 and 3), and that the asphaltene content increases in pitch as the conversion increases (Figure 4) . In Figures 2, 3 and 4, feed A is a waste of Cold Lake and feed B is a vacuum residue fractionated by viscosities derived from mixture 24 of Venezuela. The curves for the Cold Lake residue show that there are similar changes in the pitch properties when untreated material is subjected to hydrofraction. For both raw materials, there is a uniform destruction of the feed asphaltenes (Figure 5) and a deterioration in the properties of the pitch mentioned above. The decrease in pitch hydrogen content indicates condensed aromatic ring structures, and the increase in nitrogen indicates that these ring structures are more polar. These changes are very significant and are considered irreversible for previous systems.

Example 3 Examples 1 and 2 are made without feeding additional aromatic oil to the hydrofractioner. This example shows the effects of adding additional aromatic oil in the form of vacuum gas oil (VG0). The raw material in this case is a residue Cold Lake of 5.5 ° API, 5.0% sulfur, 0.6% nitrogen and 15% boiling below 524 ° C. This material is obtained from a test in a refinery and contains up to 20% Western Canadian mix. The gas oil obtained from a test once used with this raw material with conversions of 86% is 14.9% API, 2.2% sulfur, 0.53% nitrogen and has 10%, 50% and 90% points of 330, 417 and 497 ° C, respectively. Tests were carried out which simulate the reuse of 30, 50, 75 and 100% of the gas oil produced in a utilization base once, which corresponds to 8.5, 14.1, 19.5 and 24.5% by weight of fresh feed respectively in figures 6- 8 All tests were performed with 3.6% iron sulphate as an additive, as described in Example 2 in the waste portion of the feed vacuum tower. From figure 6 it can be seen that, the constant conversion, the quality of the pitch increases as the reuse of diesel increases. The content of hydrogen increases up to a total of 1% to 8% when diesel is reused "until extinction". In addition, the nitrogen content decreases from 240 to 200% in the pitch, in relation to fresh food. Figure 7 shows that diesel has been converted to lighter products, an additional extra feature for this operation as diesel can be converted to near extinction. All tests were performed with 3.6% additive in the fresh feed, which probably masks any reuse effect of VG0 on the coke yield. This will be discussed later in Example 4. Figure 8 shows that there is little loss of capacity with reuse of added VG0, in the amount of 8.8, 14.5, 20.1 and 25.2% by weight based on fresh feed. This is a surprising result as there is some accumulation of VGO in the reactor, which could be increased under VGO reuse conditions and which would tend to decrease the conversion. The test in the pilot plant confirms that the conversion of VGO is significantly accelerated by increasing the temperature. The above results show that: 1. An improvement in pitch quality is obtained at constant conversion when vacuum gas oil is reused in the reactor. 2. VGO is fractionated significantly to lighter products when they are reused.

Example 4 This example provides data from commercial operation of a nominal hydropracticing unit of 5000 BPD. The reactor in this case has a diameter of 2 m and a height of 21.3 m. The conditions for a test with addition of aromatic substances and reuse of pitch is as follows: Liquid loading: Fresh food * 3218 BPD, 8.5 ° API Adding aromatic substances 823 BPD Reuse of pitch 652 BPD Total feed 4693 BPD Temperature of the unit 464 ° C Pressure of the unit 13.9 MPa (2024 psi) Purity of the reuse gas 75% Conversion to 524 ° C + 92% by weight Uptake of H2 907 SCFB Additive rate -% by weight based on fresh 2.3 feed as FeS04. H20 2.6 reused somo FeS04. H20 Additive in the reactor 9.5% by weight TIOR in the reactor 1.86% as FeS * The fresh feed is the waste from a vacuum tower of fractionation by viscosity from crude Flotta. The list of products is as follows: Fuel gas 14.2% by volume, based on fresh feed IBP-204 ° C 23.9% by volume, based on fresh feed 204-343 ° C 37.9% by volume, based on fresh feed 343-524 ° C 36.9% by volume, based on fresh feed 524 ° C + 5.2% by volume, based on fresh feed The above are typical conditions for the combination of tar reuse and the addition of aromatic substances to control the polar aromatic substances in the system, to increase efficiency. Without the reuse of pitch and the addition of aromatic substances, the expected conversion to this fresh feed loading regime would be 65 to 70%, limited by the incipient coking temperature for this raw material at about 440 ° C. There is an evident improvement with respect to the operation where it only happens once, and over a pitch reuse operation without the addition of supplementary polar aromatic substances. This improvement is not only in conversion, but in the additive use, as shown in Figure 9, a graph of the coke / additive ratio in the reactor versus additive concentration in the reactor. The historical "step once" amounts for the reactor additives are in the 1/2% range. Now, with the reuse of pitch and the addition of aromatics, these are increased to a range of 5-9% by weight due to the increased conversion, concurrent vaporization of the product and the additive that returns with the pitch. The increased concentration of additive in the reactor results in less amount of coke in the additive and in conditions for improved conversion, which includes improved addition of hydrogen to the pitch which reduces slippage in the quality of the pitch, which again all the pitch capable of conversion. The coke yield (TIOR) is also reduced by reusing VGO produced in the unit itself, as shown in Figure 10, which provides the effect of reusing VGO (as% fresh food) on the coke yield. The additive is used in amounts of 1.2, 2.3 and 3.0% by weight, based on fresh feed. The effect is smaller when the additive is sufficient, and becomes more significant at levels of low feed additive, and is very noticeable with a 1.2% additive on fresh feed.

Example 5 This example provides analysis of aromatic substances for selected streams in support of the understanding that the control of polar aromatic substances is the key to high conversion and reduced consumption of additive. Figure 11 provides the average molecular weight of pitch versus coke (TIOR) in the reactor. The increased content of average aromatic carbon in the reactor content, as shown by the lines, allows operating with a high content of coke in the reactor. In all the commercial examples in Figure 11, the mesophase coke levels are much less than 5 microns. The increased stability provided by the aromatic oil allows higher reactor operating temperatures which allow the maintenance of the average molecular weight of the pitch low enough for coking control even with raw material extremely difficult to convert. Table 1 provides the hydrocarbon type analysis for the aromatic petroleum (in this case petroleum in suspension or petroleum decanted from a fluid catalytic catalyst) or for other foods and products mentioned in the previous examples. The VGO generated in the process and the decanting oil are clearly similar. These samples are taken during a test in which the commercial plant of Example 4 is operating with a waste feed of the vacuum tower fractionated by viscosities, with reuse of pitch and addition of suspended oil similar to that of Example 4. Table 1 shows that the proportion of the aromatic substances and the polar aromatic substances in relation to insoluble asphaltenes nC7 is reduced both in the content of the reactor and in the pitch not converted in relation to the food. The proportion of the aromatic substances + polar aromatic substances with respect to the asphaltene in the WR feed is approximately 3.86. This proportion decreases as the feed converts with the proportion in the non-converted pitch decreasing to 2.07. For VGO and aromatic oil, the diaromatic, triaromatic and tetraaromatic substances are predominant, and the currents seem to be interchangeable. Table 2 shows a decomposition of aromatic substances for the different raw materials and products. Table 3 shows an elemental analysis of the reactor feed, the reactor sample and the unconverted pitch. The residues or bottom of the vacuum tower fractionated by viscosities (polar phases) are very low in hydrogen content and approximately 8.2% by weight have a very high nitrogen content of 1.1% by weight. The hydrogen content of the saturated phase is significantly greater at 13.8% by weight. Solvent portion nC7 of the feed WR has a hydrogen content of about 10.2% by weight and a nitrogen content of about 0.43% by weight. It is found that the content of the reactor and the unconverted pitch have a similar composition. The nitrogen content of the polar aromatic phase is shown to have been elevated both in the reactor content and in the unconverted pitch, in relation to the fresh feed. The nitrogen content of the aromatic fraction of the reactor content and the unconverted pitch is found to be approximately the same as the fresh feed. The combination of the data in table 1 and table 3 shows that the nitrogen content of the polar aromatic substances is concentrated at the same time that the relative amount of polar aromatic substances relative to asphaltenes decreases. Table 4 shows the distribution of aromatic carbon in the polar, aromatic and saturated aromatic fractions of the feed pitch, of the reactor and unconverted. The aromaticity of the aromatic and polar aromatic phases increases significantly in relation to the food. However, the quaternary carbons are reduced as a ratio to the total aromatic carbons. The quaternary carbons in the fresh WR feed constitute up to 49 percent of the aromatic carbons in the aromatic and polar aromatic phases. This is reduced to 43 percent of the aromatic carbons in the unconverted pitch, in the aromatic and polar aromatic phases. Figure 12 shows a graph showing the ratio of the amount of quaternary carbon present in the aromatic and polar aromatic phases to the proportion of the polar aromatic phase which is combined with the combined aromatic polar and aromatic phases. The data presented in the previous examples show that the aromatic substances that surround the asphaltenes are converted at a faster rate in relation to the asphaltenes. If the aromatic phase remains in equilibrium with the asphaltenes, and the polar force of the polar aromatic phase is limited by dilution by less polar aromatic substances, then the mesophase generation tendency can be controlled and a high conversion of materials can be obtained very difficult to process premiums.

Table 1 ANALYSIS OF THE HYDROCARBON TYPE OF OIL FRACTIONS Fractions Sample Method Saturated Aromatics Polar asphaltenes (C) Low-resolution EM naphtha 84.73 15.26 Distillation EM of low resolution 54.35 45.65 VGO light EM low resolution 32.37 67.63 Low resolution EM aromatic oil 14.72 81.60 chromatography 15.54 80.81 3.65 VGO EM low resolution 18.74 77.74 chromatography 20.52 75.98 3.50 Feeding11 low resolution EM 22.69 52.95 (VVR) chromatography 23.28 51.40 25.32 16.57 Brea * low resolution EM 14.20 62.78 chromatography 14.23 64.48 21.29 29.49 Reactor * Low resolution MS 14.89 71.35 Middle part (R / A) chromatography 15.24 70.04 14.72 24.96 * The results are based on a deasphalted sample.

Table 2% by weight Mono di tri tetra Penta + aromatic aromatic aromatics aprététps Naphtha 15 - Distillate 27 16 Light VGO 20 37 5 VGO 4 22 25 10 Aromatic oil 2 23 30 9 Food VVR 9 8 7 3 12 * Brea 2 8 5 6 12 * It has been deasphalted. Table 3 ELEMENTARY ANALYSIS OF PETROLEUM FRACTIONS Elemental (% by weight) Fraction Sample Carbon Hydrogen Nitrogen Feed VVR 85.0 8.2 1.1 Polar substances Average part of the reactor 87.0 6.5 2.0 Brea 86.8 6.5 1.8 Aromatic substances Food VVR 86.4 9.5 0.3 Average part of the reactor 89.6 6.8 0.3 Brea 89.3 6.8 0.2 Power VVR 86.0 13.8 0.0 Saturated substances Average part of the reactor 86.0 14.0 0.0 Brea 86.0 13.8 0.0 Table 4 AROMATIC CARBON NMR ANALYSIS IN PETROLEUM FRACTIONS Quaternary carbons Protonated carbon Aromaticity (moles%) (moles%) Fraction Sample substituted poly total total mono poly () (01) (Q2) (Hb) (Ha) Power VVR 10.0 12.3 22.3 7.8 15.7 23.5 0.46 Polar substances Average part of the reactor 10.7 19.6 30.3 8.5 31.9 40.4 0.71 Brea 9.7 23.3 33.0 8.1 31.6 39.8 0.73 Food VVR 9.2 11.9 21.1 7.6 11.2 18.8 0.40 Aromatic substances Average part of the reactor 12.3 17.9 29.3 10.2 35.1 45.3 0.75 00 Brea 12.7 15.5 28.2 8.7 31.8 40.5 0.67 VVR feed 0.6 1.8 2.3 1.9 0.6 2.5 0.05 Saturated substances Average part of the reactor 0.4 1.0 1.4 1.3 0.5 1.7 0.03 Brea 0.5 2.3 2.8 1.1 0.4 1.5 0.04 Examples of carbon type in a hypothetical molecule.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, property is claimed as contained in the following:

Claims (11)

1. A process for hydrofractioning a heavy hydrocarbon petroleum feedstock, a substantial portion of which boils at a temperature greater than 524 ° C, which comprises: (a) passing a feed or suspension feed from a mixture of raw material of heavy hydrocarbon oil and from about 0.01-4.0% by weight (based on fresh raw material) of additive coke inhibitor particles comprising particles of an iron compound having sizes less than 45 μm upwards, through a confined vertical hydrofraction zone, in the presence of hydrogen, the hydrofraction zone is maintained at a temperature between approximately 350 ° and 600 ° C, a pressure of at least 3.5 MPa and a space velocity of up to 4 volumes of hydrocarbon oil per hour per volume of hydrofraction zone capacity, (b) remove an effluent from the upper part of the hydrofraction zone and mixed containing a gaseous phase consisting of hydrogen and hydrocarbons in vapor form, and a liquid phase consisting of heavy hydrocarbons, (c) passing the mixed effluent in a hot separating vessel, (d) extracting from the top of the separator a gaseous stream consisting of hydrogen and hydrocarbons in the form of vapor, (e) extracting from the waste or from the bottom of the separator a liquid stream consisting of liquid hydrocarbons and particles of the additive that inhibits the coke, (f) fractionating the separated liquid stream to obtaining a pitch waste stream which boils at a temperature above 495 ° C, the pitch stream contains additive particles, and (g) reusing or recycling at least part of the pitch stream containing additive particles for form part of the raw material for the hydrofraction zone, the process is characterized in that the hydrofraction is carried out in absence of an active hydrogenation catalyst and a heavy aromatic gas oil fraction obtained during the fractionation of the liquid waste stream of the hot separator that is reused to form part of the raw material for the hydrofractionation zone.

2. The process according to claim 1, characterized in that the aromatic heavy gas oil has a boiling point greater than about 400 ° C.

3. The process according to claim 1, characterized in that the iron compound is iron sulfate.

4. The process according to claim 3, characterized in that at least 50% by weight of iron sulphate has particle sizes of less than 10 μm.

5. The process according to claim 3, characterized in that the recycled heavy gas oil stream comprises approximately 15 to 50% by weight of the raw material for the hydrofraction zone.

6. The process according to claim 5, characterized in that the pitch reuse stream contains iron sulphate particles comprising about 5 to 15% by weight of the raw material for the hydrofraction zone. The process according to claim 6, characterized in that the heavy hydrocarbon petroleum raw material is a vacuum residue fractionated by viscosities. The process according to claim 6, characterized in that the heavy hydrocarbon petroleum raw material is a product rich in asphaltene from the deasphalting process. 9. The process according to claim 6, characterized in that the heavy hydrocarbon petroleum raw material is processed before the hydrofraction to remove the paraffinic material with high boiling point. 10. The process according to claim 6, characterized in that the waste stream or pitch background boils at a temperature above 524 ° C. 11. The process according to claim 6, characterized in that part of the fractionated heavy hydrocarbon stream boils at a temperature higher than 495 ° C and comprises a pitch product of the process, and this pitch is fed to a thermal fractionation process. . SUMMARY OF THE INVENTION A process for hydrofractioning a heavy hydrocarbon petroleum feedstock is described, a substantial portion of which boils above 524 ° C, which process includes the steps of: (a) passing a feed suspension of a mixture of heavy hydrocarbon petroleum raw material and from approximately 0.01-4.0% by weight (based on fresh raw material) of additive particles that inhibit coke upwards, through a confined vertical hydrofraction zone, the hydrofractionation zone it is maintained at a temperature between about 350 ° and 050 ° C and a pressure of at least 3.5 MPa and a space velocity of up to 4 volumes of hydrocarbon oil per hour per volume of hydrofraction zone capacity; (b) removing from the upper part of the hydrofraction zone a mixed effluent containing a gaseous phase comprising hydrogen and hydrocarbons in the form of vapor and a liquid phase consisting of heavy hydrocarbons; (c) passing the mixed effluent in a hot separating vessel; (d) extracting from the upper part of the separator a gaseous stream consisting of hydrogen and hydrocarbons in vapor form; (e) extracting from the bottom of the separator a liquid stream consisting of heavy hydrocarbons and particles of additive that inhibits the coke; and (f) fractionating the separated liquid stream to obtain a heavy hydrocarbon stream which boils at a temperature above 450 ° C, the heavy hydrocarbon stream contains additive particles and a light petroleum product. According to the novel feature, at least part of the fractionated heavy hydrocarbon stream that boils at a temperature higher than 450 ° C is reused to form part of the heavy hydrocarbon petroleum raw material to an aromatic petroleum of less polarity than it is added to the heavy hydrocarbon petroleum raw material so that a high proportion of aromatic substances of lower polarity with respect to asphaltenes is maintained during hydroprocessing. This provides excellent yields without coke formation.