Patent Grant
9920264
This application claims the benefit under 35 U.S.C. § 119 of Mexican Patent Application No. MX/a/2011/009116, filed Aug. 31, 2011, which is hereby incorporated by reference in its entirety.
The present invention relates to a process of the refining industry of petroleum: hydroconversion-distillation of heavy and/or extra-heavy crude oils, more specifically to the catalytic hydroconversion of heavy and/or extra-heavy crude oils, and distillation of hydrotreated products.
In this regard, it is important to point out that, by means of the process of the present invention products that can be processed in conventional refining schemes, designed to operate with light and intermediate crude oils are obtained.
The depletion of light and medium crude oil reserves has forced the extraction and refining of increasingly heavier crude oils, among other economic and technological type of implications, this problem has constrained the functionality of existing refineries in the world, as they were designed and built exclusively for processing light and medium crude oils and their mixtures.
Hence, many refineries have had to limit their operations and compete for the purchase of light and medium crude oils whose prices have been increasingly high.
Other refineries have invested in the installation of alternative processes that allow them for refining heavy and extra-heavy crude oils, some of these technologies are likely to be installed upstream to the processing of the heavy oil fraction (vacuum residue) such as: delayed coking, catalytic cracking of residue, solvent deasphalting, however, these technologies do not solve the initial problem of refining heavy crude.
The state-of-the-art closest to the present invention, by referring to the use of processes which combine multiple steps and/or refining steps (combined processes) to improve the properties of the heavy and extra-heavy crude oils, is here represented by the following patent documents:
Previous technologies known by the applicant, were overcome by the present invention, since these technologies relate to conversion of crude processes for obtaining hydrocarbon cuts that can be refined upstream by means of known processes such as catalytic cracking, hydroconversion, deasphalting or coking, however, none of the cited references note and even suggest a hydroconversion-distillation process of heavy and/or extra-heavy crude oils.
It is therefore an object of the present invention to provide a process which comprises the catalytic hydroconversion of heavy and/or extra-heavy crude oils, and the distillation of the hydrotreated products.
An additional object of the present invention is to provide a process to obtain products that can be processed in conventional refining schemes, designed to operate with light and intermediate crudes.
A process has been discovered for the hydroconversion-distillation of heavy and extra heavy crude oils, which comprises desalting and separation of a feedstock comprising heavy and/or extra heavy crude oil to obtain a light fraction and a heavy fraction; subjecting the light fraction to catalytic hydrotreatment to obtain a hydrotreated fraction; subjecting the heavy fraction to catalytic hydroconversion; and distillation of the hydrotreated fraction to obtain distilled fractions that can be processed in conventional refining schemes, which are designed to process light and medium crude oils.
According to one embodiment of the invention, the feedstock to the desalting and separation of the feedstock is crude oil having 3 to 30 API gravity units, preferably 3-22 API gravity units, and most preferably 3-10 API gravity units, and the desalting and separation of the feedstock, operates at atmospheric pressure and temperatures from 280 to 420° C.
According to another embodiment of the invention, catalytic hydrotreating of the light fraction, is optional and may be omitted when the crude oil is so heavy that only a small volume of a light fraction is obtained, which fraction may be passed directly to distillation.
Catalytic hydrotreating of the light fraction may be carried out in a conventional reactor with catalysts of nickel-molybdenum (Ni—Mo) or cobalt-molybdenum (Co—Mo), in extruded or spherical shape, under a pressure of 10 to 80 kg/cm2, hydrogen to hydrocarbon ratio of 350 to 3,000 ft3/bbl, temperature of 280 to 380° C. and the volumetric feed flow related to catalyst volume (LHSV) of 0.5 to 3 h−1.
According to another embodiment, catalytic hydroconversion of the heavy fraction may be carried out in two or more fixed-bed reactors connected in series, and the fixed-beds of the reactors may be loaded with three types of extrudate catalysts in different proportions. The catalysts of the fixed-beds of the reactors contain metals such as Pt, Pd, Ni, Mo and Co, among others, preferably Ni, Mo and Co, at concentrations of 2 to 15 weight % of each one in the fresh catalysts. In one embodiment, each of the catalyst beds has a higher metal concentration than the preceding catalyst bed. The catalysts of the fixed-beds may be supported on aluminum oxides, silica, titanium, and mixtures thereof, preferably on aluminum oxide (alumina) in its gamma phase, using particle sizes ranging from 1 to 3 mm diameter in cylindrical or extruded with different profiles, tablets or lobular shapes. The catalyst bed may be first preferably loaded with a hydrodemetallization catalyst in concentrations of 0.1 to 3 weight % of nickel and from 1 to 5 weight % of molybdenum, supported on gamma alumina. Next, the catalyst bed is loaded in an intermediate section, preferably with a hydrogenation-hydrocracking catalyst in concentrations of 0.5 to 5 weight % of nickel and 2 to 8 weight % of molybdenum, supported on gamma alumina. In one embodiment, the nickel and molybdenum concentration in the intermediate section is higher than the nickel and molybdenum concentration in the first catalyst bed.
The catalyst bed is loaded in its final section, preferably with a hydrogenating catalyst in concentrations of 1 to 5 weight % of nickel and from 5 to 12 weight % of molybdenum supported on gamma alumina. The nickel and molybdenum concentration in the final section is greater than the nickel and molybdenum concentration in the intermediate and first sections. The catalytic hydroconversion of the heavy fraction is carried out at a pressure of 40 to 130 kg/cm2, a hydrogen to hydrocarbon ratio of from 2,000 to 7,000 feet3/bbl, a temperature of 320 to 450° C. and a volumetric feed flow related to catalyst volume (LHSV) of 0.2 to 3 h−1.
According to another embodiment, distillation of the hydrotreated products is carried out in an atmospheric distillation column, and thereafter in a vacuum distillation column, resulting in a product having similar properties to light and medium crude oils usually processed in a refinery scheme.
The volumetric yield of the fractions obtained from a heavy and/or extra-heavy crude oils is, for example, light naphtha up to 1%, intermediate naphtha up to 2%, heavy naphtha up to 3%, light distillate up to 4%, heavy distillate up to 7%, straight-run gas oil up to 5%, light vacuum gas oil up to 12%, and heavy vacuum gas oil up to 5%; and a decrease of the vacuum residue as much as 30%.
The process of the present invention removes impurities contained in heavy and/or extra-heavy crude oils, hydrodemetallization up to 90%, hydrodesulfurization up to 90%, hydrodenitrogenation up to 70%, carbon removal up to 60%, and asphaltenes removal up to 70%.
The present invention relates to a process of the petroleum refining industry: hydroconversion-distillation of heavy and/or extra-heavy crude oils, more specifically to the catalytic hydroconversion of heavy and/or extra-heavy crude oils, and atmospheric and vacuum distillations of the hydrotreated product.
In this respect, it is important to point out that, by means of the process of the present invention such products that can be processed in conventional refining schemes designed to operate light and intermediates crudes are obtained.
The process of the present invention processes feedstocks with API gravity in the range of 3 to 30° API, and because of the nature of the feeds it comprises preheating of the same feed and feeding lines, in order to comply with optimal properties for transport (particularly viscosity) to the crude oil fractionation zone. Preheating of the feed can be carried out by heat exchange with hot streams of the same unit, while the heating pipes can be carried out using steam jackets. Under these conditions, it is necessary to guide the settlement process and equipment to optimize the energy balance when dealing with streams of high molecular weight and high viscosities.
1) Desalting and separation of the feedstock;
2) Catalytic hydrotreating of the light fraction (optional);
3) Catalytic hydroconversion of the heavy fraction, and
4) Distillation of the hydrotreated products.
Step 1) Desalting and separation of the feedstock, that can be considered as a preparation of the feedstock (heavy and/or extra-heavy crude oils) to steps 2) and 3), consisting in desalting the heavy and/or extra-heavy crude oil, and adjusting the boiling range of light and heavy cuts, operating at atmospheric pressure and temperature of 280 to 420° C., prior to stages of hydrotreating and catalytic hydroconversion of said fractions, respectively. Step 2) catalytic hydrotreating of the light fraction is optionally carried out and would be performed at less severe operating conditions than those of step 3) catalytic hydroconversion of heavy fraction.
In this regard it is important to note that the separate treatment of these two fractions brings benefits on reduced investment and operating costs as the two fractions are hydrotreated by using different catalysts, operating conditions and type of reactors. Adjusting the boiling temperature of the two fractions is carried out by distillation. Typically, the light fraction comprises hydrocarbons with a boiling temperature below 360° C., while the heavy fraction comprises compounds with higher boiling temperature than this temperature until the final boiling point of the petroleum feedstock. These values are defined depending on the type and quality of petroleum feedstock and refining scheme.
For example, in an extra-heavy crude oil the light fraction can be very small if the fractionation is carried out at a very low final boiling temperature, so that the fractionation temperature is raised to increase the volume of this fraction. On the other hand, in a heavy crude oil the light fraction can be bigger and would require a decrease in the final temperature cut during fractionation. These decisions are made based on the type of crude to be processed, the operating conditions of the reactors, the size of the reactors (processing capacity) and on the desired properties of the final product.
The process of the present invention has the flexibility to operate under different qualities of the feedstock and required products.
In step 2) catalytic hydrotreating of the light fraction, due to its boiling temperature range (the initial boiling point of petroleum and cutting temperature in the first stage), the light fraction can mainly contain impurities of sulfur and nitrogen. The complexity of the molecules includes up to alkyl benzothiophenes, whose difficulty for removal occurs by steric hindrances. This fraction contains cuts of the type of naphthas, middle distillates and a small fraction of gasoils. The relative composition of each cut depends on the type of petroleum feed and the final boiling temperature of the light fraction.
The catalytic hydrotreatment of this light fraction can be carried out in a conventional reactor operating with catalysts of nickel-molybdenum (Ni—Mo) or cobalt-molybdenum (Co—Mo), in extruded form. The operating conditions of the reaction zone for the catalytic hydrotreatment are: operating pressure of 10 to 80 kg/cm2, hydrogen to hydrocarbon ratio of 350 to 3,000 ft3/bbl, temperature of 280 to 380° C. and liquid hourly space velocity (LHSV) of 0.5 to 3 h−1; all other operating conditions of the catalytic hydrotreatment plant will be those provided in similar conventional units.
A variant of the process of the present invention is that it has the option of whether or not hydrotreat the light fraction mainly depending on the required quantity and quality of the products, because if the crude oil feedstock is so heavy, the volume of this fraction is very small. In this circumstance, it is desirable to directly feed this light fraction to atmospheric distillation column of step 4).
Step 3) catalytic hydroconversion of heavy fraction that has several purposes: on the one hand the reduction of content of impurities such as organometallic, sulfur and nitrogen compounds, and on the other hand reducing viscosity and increasing the API gravity of the feedstock. The catalytic hydroconversion is carried out in two or more fixed-bed reactors connected in series, the catalytic beds are loaded with three types of extrudate catalysts in different proportions. Each catalytic bed preferably has a catalyst concentration that is higher than the preceding catalyst bed such that the catalyst concentration increases from the feed end to the outlet end.
One of the properties of the catalytic bed is to have a hydrogenating function, which is achieved with catalysts containing metals that have the property to chemisorb hydrogen atoms such as: Pt, Pd, Ni, Mo and Co, among others, preferably Ni, Mo and Co, for their resistance to sulfur poisoning, in concentrations from 2 to 15 weight % each in the fresh catalyst.
Another important function of the catalyst bed is to retain the heavy metals containing in the heavy oil, mainly Ni, V, Fe, Cu and Pb; consequently a support is selected with high porosity such as oxides of aluminum, silica, titanium and mixtures thereof, these supports should also have adequate mechanical properties for reactor operation at high pressures and temperatures, and adequate size to avoid high pressure drops. The most suitable catalysts for this process typically use aluminum oxide support (alumina) in its gamma phase and particle sizes ranging from 1 to 3 mm diameter either cylindrical or extruded shapes with different profiles, tablets, or lobular.
An additional function of the catalyst bed used in the process of the present invention is to convert the sulfur and nitrogen compounds in the feedstock to hydrogen sulfide and ammonia, respectively; which is accomplished, to some extent, taking advantage of the catalyst property of chemisorb atoms of hydrogen, sulfur and nitrogen, whose function is properly performed by the active metals Ni and Mo in sulfide form by breaking the C—S—C and C—N—C bonds and saturate the sulfur and nitrogen to form hydrogen sulfide and ammonia respectively.
First in the catalyst bed a hydrodemetallization catalyst is loaded whose function is to partially hydrogenate the molecules of the heavy compounds, for which the catalyst has a relatively low hydrogenating function capable to hydrocrack; the catalyst permits reactions to favor removal of heavy metals. Such a catalyst contains low amounts of nickel and molybdenum supported on gamma alumina in concentrations of 0.1 to 3 weight % of nickel and 1 to 5 weight % of molybdenum.
The intermediate portion of the catalyst bed has hydrogenation-hydrocracking balanced functions, hydrogenation function allows more reactions for promoting the removal of sulfur and nitrogen as well as the saturation of aromatics present in the separate chains of large molecules by the effect of the hydrocracking function, to meet these objectives, the catalyst of the intermediate zone of the catalytic bed is formulated with 0.5 to 5 weight % of nickel and from 2 to 8% by weight of molybdenum. The catalyst concentration in the intermediate zone is preferably higher than in the first catalyst bed.
The final part of the catalyst bed is loaded with a catalyst, mainly for the hydrogenating function to favor the removal of sulfur and saturation of the hydrogen deficient species; the concentrations of active metal in this catalyst are 1 to 5% by weight of nickel and 5 to 12 weight % of molybdenum. The catalyst concentration in the final bed is preferably higher than in the intermediate zone.
The three types of catalysts are loaded into the reactor using the procedures applicable to the industrial scale, in addition to the catalyst bed relaxer pressure drop materials that may or may not have catalytic activity for hydrogenation, hydrocracking, or both must be loaded. Different profiles of shape can be used in the active catalysts such as cylindrical extruded, lobe or spheres in sizes ranging from 1 to 3 millimeters in diameter. Relaxants materials may also have different shape, including: spheres, tablets, raschig rings and similar.
In order to adequately fulfill the processing of crude oil, the process of the present invention employs at least two fixed-bed reactors, with the arrangement of several reactors having the following main advantages:
As a result of the exothermic nature of the reactions, it is necessary to add hydrogen streams along the catalyst bed and the inlet of the second reactor, the effect of addition of the hydrogen stream is:
The operating conditions of the reaction zone are: pressure of 40 to 130 kg/cm2, temperature of 320 to 450° C., hydrogen/hydrocarbon ratio from 2,000 to 7,000 ft3/bbl, and space velocity (LHSV) of 0.2 to 3 h−1. Depending on the quality of the feedstock and the desired results in products of the process, it is possible to combine these different values of operating variables.
Step 4) Distillation of the hydrotreated products, that comprises the feeding of the light and heavy fractions obtained in steps 2) and 3) to an atmospheric distillation column.
The light fraction fed to the atmospheric column might be hydrotreated or not, depending on their levels of contaminants such as sulfur or nitrogen and especially its volumetric content in the petroleum feed; the point of feeding of the light fraction obtained in step 2) to the atmospheric distillation column depends on the particular design of this column and is usually fed into the intermediate portion of the column, depending on its composition and temperature profile of the column.
Moreover, the heavy fraction obtained in step 3) is always added to the bottom of the atmospheric distillation column.
In this primary distillation naphtha and middle distillates cuts are obtained, and the atmospheric residue as well; the latter is fed to the vacuum distillation column where the light and heavy vacuum gasoils cuts and vacuum residue are obtained. All fractionated cuts in both the primary and vacuum distillation columns, are sent to the various downstream refining processes.
Among the main technical contributions of the process of the present invention, compared with conventional refining processes are the following:
To better illustrate the process of the present invention, below are some examples, which do not limit the scope of what is claimed herein.
A heavy crude oil with 15.93° API and complimentary properties presented in Table 1, was subjected to step 1) Desalting and separation of the feedstock, of the process of the present invention, obtaining a light fraction and a heavy fraction with 42.61 and 6.78° API, respectively, among other properties shown in Table 1.
From Table 1, it is important to emphasize the zero contents of n-heptane-insolubles (asphaltenes), nickel and vanadium in the light fraction, which ensures that the catalysts used in step 1) desalting and separation of the feedstock, do not experience significant deactivation during the time-on-stream. Such impurities are concentrated in the heavy fraction which is fed to step 2) catalytic hydrotreating of the light fraction, wherein the catalysts used here suitable properties for accumulating heavy metals, and breaking the complex molecules of asphaltenes to produce lighter distillates.
The light fraction obtained in the step 1 of Example 1 was subjected to a second step 2) Catalytic hydrotreating of the light fraction, of the process of the present invention, at the operating conditions indicated in Table 2.
The properties of the product obtained in step 2) of Example 1, are shown in Table 3.
From Table 3 it is important to note the considerable reduction of sulfur content in the product, from 1,748 weight % of sulfur in the light fraction (Table 1) to 0.048 weight % of sulfur in the product (Table 3).
The heavy fraction obtained in step 1) of Example 3 was subjected to Step 3) catalytic hydroconversion of heavy fraction, using two fixed-bed reactors connected in series at the operating conditions shown in Table 4.
Product properties obtained in the step 3) of Example 1, are shown in Table 5.
From Table 5, it is important to underline the considerable increase in API gravity: from 6.78 in the heavy fraction (Table 1) to 18.17 in the product (Table 5), ensuring higher production of valuable distillates.
The hydrotreated light and hydroconverted heavy fractions obtained in stages 2) and 3) of Example 1 were subjected to step 4) Distillation of the hydrotreated products, of the present invention. The yields and properties of the distillates obtained from this fractionation are shown in Table 6.
From Table 6 it is important to note the significant reduction in the recovered fraction at 538° C., volume % or vacuum residue, from 54.59 volume % in the heavy oil feed (Table 1) to 24.5 volume % in the product (Table 6). This reduction increases the production of other distillates.
A heavy crude oil with 21.24° API and other properties presented in Table 7, was subjected to step 1) desalting and separation of the feedstock of the present invention, obtaining light and heavy fractions with 42.98 and 6.97° API respectively, among other properties presented in Table 7.
The light fraction obtained in the step 1) of Example 2, was subjected to a second step 2) Catalytic hydrotreating of the light fraction, of the process of the present invention, at operating conditions indicated in Table 8.
Product properties obtained in step 2) of Example 2 are shown in Table 9.
The heavy fraction obtained in step 1) of Example 2 was subjected to Step 3) Catalytic hydroconversion of the heavy fraction, of the process of the present invention, using two fixed-bed reactors connected in series at the operating conditions shown in Table 10.
Properties of the product obtained in step 3) of Example 2 are shown in Table 11.
The hydrotreated light and hydroconverted heavy fractions obtained in stages 2) and 3) of Example 2, were subjected to step 4) distillation of the hydrotreated products, of the present invention. The yields and properties of the distillates obtained from this fractionation are shown in Table 12.
A heavy crude with 15.93° API and the properties presented in Table 13, was subjected to step 1) desalting and separation of the feedstock, of the process of the present invention, obtaining a light and heavy fractions were with 42.61 and 6.78° API, respectively, among other properties presented in Table 13.
The light fraction obtained in the step 1) of Example 3 was not subjected to a second step 2) catalytic hydrotreating of the light fraction, of the process of the present invention.
The heavy fraction obtained in step 1) of Example 3 was subjected to Step 3) catalytic hydroconversion of heavy fraction, of the process of the present invention, using two fixed bed reactors connected in series at the operating conditions shown in Table 14.
The properties of the product obtained in step 3) of Example 3 are shown in Table 15.
The light fraction obtained from step 1) and the hydroconverted heavy fraction obtained in step 3) of Example 3 were subjected to step 4) distillation of the hydrotreated products, of the present invention. The yields and properties of the distillates obtained from this fractionation are shown in Table 12.
| Number | Date | Country | Kind |
|---|---|---|---|
| MX/a/2011/009116 | Aug 2011 | MX | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3684700 | Langlois et al. | Aug 1972 | A |
| 4039429 | van Klinken et al. | Aug 1977 | A |
| 4396493 | Eilers et al. | Aug 1983 | A |
| 4415436 | Angevine | Nov 1983 | A |
| 4534847 | Roberts et al. | Aug 1985 | A |
| 4591426 | Krasuk et al. | May 1986 | A |
| 4655905 | Plumail et al. | Apr 1987 | A |
| 4756821 | Giuliani et al. | Jul 1988 | A |
| 4885080 | Brown et al. | Dec 1989 | A |
| 5417846 | Renard | May 1995 | A |
| 6277270 | Morel et al. | Aug 2001 | B1 |
| 6303089 | Wallace et al. | Oct 2001 | B1 |
| 6306287 | Billon et al. | Oct 2001 | B1 |
| 6342152 | Yoshita | Jan 2002 | B1 |
| 6447671 | Morel et al. | Sep 2002 | B1 |
| 7651604 | Ancheyta-Juarez et al. | Jan 2010 | B2 |
| 20020008049 | Inomata et al. | Jan 2002 | A1 |
| 20020130063 | Vuillemot et al. | Sep 2002 | A1 |
| 20030000867 | Reynolds | Jan 2003 | A1 |
| 20030111387 | Mukherjee et al. | Jun 2003 | A1 |
| 20050101480 | Ackerman et al. | May 2005 | A1 |
| 20070187294 | Ancheyta Juarez et al. | Aug 2007 | A1 |
| 20090261016 | Marchionna et al. | Oct 2009 | A1 |
| 20100122934 | Haizmann et al. | May 2010 | A1 |
| 20100176032 | Droughton | Jul 2010 | A1 |
| 20100230323 | Ancheyta Juarez | Sep 2010 | A1 |
| 20110155639 | Colyar | Jun 2011 | A1 |
| Entry |
|---|
| Refining Process Handbook, Chapter 1 Refinery Distillation, pp. 1-28, 2006. |
| Surinder Parkash, Refining Processes Handbook, Chapter 1 Distillation, Gulf Professional Publishing, Oct 2003, pp. 1-28. |
| Number | Date | Country | |
|---|---|---|---|
| 20130056394 A1 | Mar 2013 | US |
