CATEGORY: CATALYSIS
China Petroleum Processing and Petrochemical
Technology, 2013, Vol. 15, No. 2, pp 1-5
Development
and Commercial Application of Third Generation Resid Hydrotreating Catalysts
Hu Dawei; Yang Qinghe; Dai Lishun; Zhao Xinqiang
Research Institute of Petroleum Processing, SINOPEC, Beijing 100083
Abstract:
Based
on the mechanism of resid hydrotreating reaction by coordinating the catalyst
activity and stability, the diffusion mechanism and catalyst reactivity, the
cost and catalyst performance, and the production and application requirements,
the third-generation series catalysts for residue hydrotreating have been
developed by Research Institute of Petroleum Processing, SINOPEC. The new
series RHT catalysts possess higher activity for HDS, HDM and HDCCR performance
as well as longer run length.
Introduction
Among residue processing methods, the fixed bed hydrotreating technology
combined with the fluid catalytic cracking process is becoming one of the most
attractive processes for deep conversion of residue. Residue hydrotreating can
greatly improve the FCC feed quality. Most of the sulfur, nitrogen, metals and
Concarbon (resins, asphaltenes and so on) are removed, and the hydrogen content
of the feed is increased, resulting in more valuable light fractions obtained
from FCC than other residue processing technologies[1-2]. The key of fixed bed
residue hydrotreating technology is to develop a good performance catalyst
system. Based on the knowledge on reaction mechanism of residue hydrotreating
and the experiences in ten years commercial application of the RHT series
catalysts, the third generation RHT catalysts were developed by Research
Institute of Petroleum Processing, SINOPEC (RIPP) in 2011. The new series
catalysts have been commercialized in the 3.1 Mt/a RDS unit of the Hainan
refinery and in the 1.5 Mt/a UFR-VRDS unit of the SINOPEC Qilu Company refinery
soon afterwards.
Free Full Text Source: http://www.chinarefining.com/EN/article/downloadArticleFile.do?attachType=PDF&id=173
Showing posts with label RESIDUE. Show all posts
Showing posts with label RESIDUE. Show all posts
Monday, September 30, 2013
Thursday, July 19, 2012
A new method of evaluation of direct distillability of residual fuels
Chemistry and Technology of Fuels and Oils, Volume 48, Number 2 (2012), 162-168
AuthorsV. T. Bugai (1)
E. A. Sharin (1)
A. A. Sautenko (1)
M. I. Fakhrutdinov (1)
Author Affiliations1.FAU 25 State Scientific Research Institute of Chemmotology, Ministry of Defence of Russia (FAU 25 GosNII Khimmotologii Minoborony Rossii), Moscow, Russia
Abstract
Discusses problems of evaluation of direct distillability of residual fuels, i.e., presence in them of residues of oil refining destructive processes.
The method provides reliable information about the presence of residues of destructive origin in the fuels.
Full Text Source (Subscription or Fee): http://www.springerlink.com/content/n4783m7454850185/
Wednesday, July 18, 2012
Comparison of Structural Properties of Pitches Prepared from Petroleum Refinery/Petrochemical Residues using NMR Spectroscopy
The Open Petroleum Engineering Journal, 2012, 5, 14-20
Manoj Srivastava*, Manoj Kumar, U. C. Agrawal and M. O. Garg
CSIR - Indian Institute of Petroleum, Dehradun 248 005, India
Abstract:
INTRODUCTION
Today, petroleum refining industry is facing unprecedented challenges like declining crude quality and more severe product specifications. One main challenge before petroleum refiners/petrochemical producers is the effective utilization of petroleum residues produced during various petroleum refinery/petrochemical processes. Generally, these residues are used as blending streams for fuel oils but the market of fuel oil is shrinking. To fetch substantial money out of these low value petroleum residues, one way is to convert these petroleum residues into pitch. Pitch is a widely used precursor for making many low volume but high cost ‘industrial’ and ‘advanced’ carbon materials [1]. Pitch is generally prepared by thermal treatment of petroleum/coal derived residues. The inherent complexity of petroleum residues increases the pitch complexity many more times. The properties of pitch are largely dependent on feed properties, thermal treatment temperature, residence time, pressure and additives used. The proper selection of these variables leads to formation of desired quality of pitches. The feed stock constituents and their reactivity greatly influence the properties of pitch. The knowledge of structural composition of isotropic pitch is also important for their conversion into mesophase pitch and thereafter production of various carbon materials namely needle coke, carbon fibers, meso carbon micro beads (MCMB) etc. NMR spectroscopy [2] is one of the powerful tools for structural characterization of feed stocks as well as pitches. It helps to quantify the different kinds of carbon and hydrogen atoms depending on their location and bonding within the molecules.
In the present study, various petroleum-derived residues were characterized and converted into pitches. The main objective of this work is to carry out a detailed study to correlate physico-chemical properties of feed stocks and pitches. High temperature in-situ NMR studies were also carried out to examine the mesophase formation behaviour in various isotropic pitches at high temperature. This will help to have a better understanding for selection of feed stocks for making ‘mesophase pitches’.
Free Full Text Source: http://www.benthamscience.com/open/topej/articles/V005/14TOPEJ.pdf
Tuesday, December 6, 2011
Process And Apparatus For Cracking Hydrocarbon Feedstock Containing Resid
PATENT
Inventors: Richard C. Stell, George J. Balinsky, James N. McCoy, Paul F. Keusenkothen
Original Assignee: ExxonMobil Chemical Patents Inc.
Patent number: 7993435
Issue date: Aug 9, 2011
Application number: 11/521,961
FIELD OF THE INVENTION
BACKGROUND
Steam cracking, also referred to as pyrolysis, has long been used to crack various hydrocarbon feedstocks into olefins, preferably light olefins such as ethylene, propylene, and butenes. Conventional steam cracking utilizes a pyrolysis furnace that has two main sections: a convection section and a radiant section. The hydrocarbon feedstock typically enters the convection section of the fumace as a liquid (except for light feedstocks which enter as a vapor) wherein it is typically heated and vaporized by indirect contact with hot flue gas from the radiant section and by direct contact with steam. The vaporized feedstock and steam mixture is then introduced into the radiant section where the cracking takes place. The resulting products comprising olefins leave the pyrolysis furnace for further downstream processing, including quenching.
Pyrolysis involves heating the feedstock sufficiently to cause thennal decomposition of the larger molecules. The pyrolysis process, however, produces molecules that tend to combine to form high molecular weight materials known as tar. Tar is a high-boiling point, viscous, reactive material that can foul equipment under certain conditions. In general, feedstocks containing higher boiling materials tend to produce greater quantities of tar.
Conventional steam cracking systems were effective for cracking high-quality feedstock which contain a large fraction of light volatile hydrocarbons, such as gas oil and naphtha. However, steam cracking economics sometimes favor cracking lower cost feedstocks containing resids such as, by way of non-limiting examples, atmospheric residue, e.g., atmospheric pipestill bottoms, and crude oil. Crude oil and atmospheric residue often contain high molecular weight, non-volatile components with boiling points in excess of 590° C. (11000 F.). The non-volatile components of these feedstocks lay down as coke in the convection section of conventional pyrolysis furnaces. Only very low levels of nonvolatile components can be tolerated in the convection section downstream of the point where the lighter components have fully vaporized.
In most commercial naphtha and gas oil crackers, cooling of the effluent from the cracking fumace is nonnally achieved using a system of transfer line heat exchangers, a primary fractionator, and a water quench tower or indirect condenser. The steam generated in transfer line exchangers can be used to drive large steam turbines which power the major compressors used elsewhere in the ethylene production unit. To obtain high energy-efliciency and power production in the steam turbines, it is necessary to superheat the steam produced in the transfer line exchangers.
Cracking heavier feeds, such as kerosenes and gas oils, produces large amounts of tar, which leads to rapid coking in the radiant section of the fumace as well as fouling in the transfer line exchangers preferred in lighter liquid cracking service.
Additionally, during transport some naphthas are contaminated with heavy crude oil containing non-volatile components. Conventional pyrolysis furnaces do not have the flexibility to process residues, crudes, or many residue or crude contaminated gas oils or naphthas which comprise non-volatile components.
To address coking problems, U.S. Pat. No. 3,617,493, which is incorporated herein by reference, discloses the use of an external vaporization drum for the crude oil feed and discloses the use of a first flash to remove naphtha as vapor and a second flash to remove vapors with a boiling point between 230 and 590° C. (450 and 11000 F.). The vapors are cracked in the pyrolysis furnace into olefins and the separated liquids from the two flash tanks are removed, stripped with steam, and used as fuel.
U.S. Pat. No. 3,718,709, which is incorporated herein by reference, discloses a process to minimize coke deposition. It describes preheating of heavy feedstock inside or outside a pyrolysis fumace to vaporize about 50% of the heavy feedstock with superheated steam and the removal of the residual, separated liquid. The vaporized hydrocarbons, which contain mostly light volatile hydrocarbons, are subjected to cracking.
U.S. Pat. No. 5,190,634, which is incorporated herein by reference, discloses a process for inhibiting coke fonnation in a fumace by preheating the feedstock in the presence of a small, critical amount of hydrogen in the convection section. The presence of hydrogen in the convection section inhibits the polymerization reaction of the hydrocarbons thereby inhibiting coke fonnation.
U.S. Pat. No. 5,580,443, which is incorporated herein by reference, discloses a process wherein the feedstock is first preheated and then withdrawn from a preheater in the convection section of the pyrolysis furnace. This preheated feedstock is then mixed with a predetennined amount of steam (the dilution steam) and is then introduced into a gas-liquid separator to separate and remove a required proportion of the non-volatiles as liquid from the separator. The separated vapor from the gas-liquid separator is returned to the pyrolysis fumace for heating and cracking.
Co-pending U.S. application Ser. No. 10/188,461 filed Jul. 3, 2002, Patent Application Publication US 2004/0004022 A1, published Jan. 8, 2004, which is incorporated herein by reference, describes an advantageously controlled process to optimize the cracking of volatile hydrocarbons contained in the heavy hydrocarbon feedstocks and to reduce and avoid coking problems. It provides a method to maintain a relatively constant ratio of vapor to liquid leaving the flash by maintaining a relatively constant temperature of the stream entering the flash. More specifically, the constant temperature of the flash stream is maintained by automatically adjusting the amount of a fluid stream mixed with the heavy hydrocarbon feedstock prior to the flash. The fluid can be water.
In using a flash to separate heavy liquid hydrocarbon fractions containing resid from the lighter fractions which can be processed in the pyrolysis furnace, it is important to effect the separation so that mo st of the non-volatile components will be in the liquid phase. Otherwise, heavy, coke-forming nonvolatile components in the vapor are carried into the furnace causing coking problems.
Increasing the cut in the flash drum, or the fraction of the hydrocarbon that vaporizes, is also extremely desirable because resid-containing liquid hydrocarbon fractions generally have a low value, often less than heavy fuel oil. Vaporizing some of the heavier fractions produces more valuable steam cracker feed. This can be accomplished by increasing the flash drum temperature to increase the cut. However, the resulting vaporized heavier fractions tend to partially condense in the overhead vapor phase resulting in fouling of the lines and vessels downstream of the flash/separation vessel overhead outlet.
Accordingly, it would be desirable to provide a process for converting materials in the liquid phase in the drum to materials suitable as non-fouling components for the vapor phase.
SUMMARY
In one aspect, the present invention relates to a process for cracking hydrocarbon feedstock containing resid comprising: heating the feedstock, mixing the heated feedstock with a fluid and/or a primary dilution steam stream to form a mixture, flashing the mixture to form a vapor phase and a liquidphase which collect as bottoms and removing the liquid phase, separating and cracking the vapor phase, and cooling the product eflluent, wherein the bottoms are maintained under conditions to effect at least partial visbreaking. In an embodiment, the mixture can be further heated prior to flashing.
In another aspect, the present invention relates to a process for cracking hydrocarbon feedstock containing resid which comprises: (a) heating the hydrocarbon feedstock; (b) mixing the heated hydrocarbon feedstock with steam to fonn a mixture stream; (c) flashing the mixture stream to fonn a vapor phase overhead and a liquid phase which collects as bottoms; (d) maintaining the bottoms under conditions suflicient to effect at least partial visbreaking of the bottoms to provide lower boiling hydrocarbons; (e) removing the bottoms; (f) cracking the vapor phase to produce an effluent comprising olefins; (g) quenching the eflluent; and (h) recovering cracked product from the quenched effluent.
In yet another aspect, the present invention relates to a vapor/ liquid separation apparatus for treating a flow of vapor/ liquid mixtures of hydrocarbons and steam, comprising: (a) a substantially cylindrical vertical drum having an upper cap section, a middle section comprising a circular wall, and a lower cap section; (b) an overhead vapor outlet extending upwardly from the upper cap section; (c) at least one inlet in the circular wall of the middle section for introducing the flow; (d) a substantially concentrically positioned, substantially cylindrical boot extending downwardly from the lower cap section for receiving separated liquid, the boot being of less diameter than the middle section and communicating with the lower cap section, and further comprising a liquid outlet at its lower end; and further comprising at least one of (e) a means for introducing heat directly to the lower cap section and/ or the boot; and (f) a means to regulate residence time of liquid present in the lower cap and/or the boot.
In still yet another aspect, the present invention relates to an apparatus for cracking a hydrocarbon feedstock containing resid, comprising: (a) a heating zone for heating the hydrocarbon feedstock to provide heated hydrocarbon feedstock; (b) a mixing zone for mixing a primary dilution steam stream with the heated hydrocarbon feedstock to provide a heated two-phase stratified open channel flow mixture stream; (c) a vapor/liquid separation zone for treating vapor/liquid mixtures of hydrocarbons and steam, the zone comprising: i) a substantially cylindrical vertical drum having an upper cap
section, a middle section comprising a circular wall, and a lower cap section; ii) an overhead vapor outlet extending upwardly from the upper cap section; iii) at least one inlet in the circular wall of the middle section for introducing the flow; iv) a substantially concentrically positioned, substantially cylindrical boot extending downwardly from the lower cap section for receiving separated liquid, the boot being of less diameter than the middle section and communicating with the lower cap section, and further comprising a liquid outlet at its lower end; and further comprising at least one of v) a means for introducing heat directly to the lower cap section and/or the boot; and vi) a means to regulate residence time of liquid present in the lower cap and/or boot; (d) a pyrolysis fumace comprising a convection section, and a radiant section for cracking the vapor phase from the overhead vapor outlet to produce an eflluent comprising olefins; (e) a means for quenching the effluent; and (f) a recovery train for recovering cracked product from the quenched eflluent.
Method For Predicting Hydrocarbon Process Stream Stability Using Near Infrared Spectra
PATENT
Inventor: Ron Sharpe
Original Assignee: Nalco Company
Patent number: 8017910
Issue date: Sep 13, 2011
Application number: 12/254,519
TECHNICAL FIELD
BACKGROUND
Crude oil typically contains several hundred thousand compounds. A common simplified analysis system classifies these compounds into four groups according to their solubility. This system is known as “SARA” analysis, where the groups are saturates, aromatics, resins, and asphaltenes. The least soluble of these groups are the asphaltenes, which can be stabilized by association with resins and/or aromatics but are destabilized by association with saturates. Asphaltenes typically exist as nano-scale stabilized dispersion in the resin, aromatics, and saturates mix. If the balance of these components is disturbed, as it can be during thermal cracking, conditions may arise where asphaltenes precipitate from solution. Among other problems, this thermal cracking can lead to coke fonnation at high temperatures and sludge in visbreaker tar residue.
Asphaltenes are of particular interest to the petroleum industry because of their depositional effect in production equipment. Asphaltenes also impart high viscosity to crude oils, negatively impacting production. Variable asphaltene concentration in crude oils within individual reservoirs creates a myriad of production problems. Refining of heavier crudes poses problems to petroleum producers and refiners. During production, unwanted asphaltene precipitation causes well plugging. During refining, asphaltenes cause refinery heat exchanger fouling, as well as catalyst poisoning by coking or binding of active sites with heavy metals.
Asphaltenes in crude oil, fuel oil, distillation residue, and the like are insoluble in heptane at its boiling point and soluble in benzene at its boiling point. They are typically black to dark brown solids having a molecular structure of polynuclear aromatic rings with alkyl side chains and heteroatoms, such as nitrogen, oxygen, and sulfur. These solubility characteristics allow its indirect measurement.
For example, U.S. Pat. No. 4,940,900 to Lambert discloses measurement of the flocculation threshold of a petroleum product containing asphaltenes by continuously adding a precipitant and measuring the near infrared radiation transmitted through a sample of the product in relation to the quantity of added precipitant. The method requires addition of both a solvent and precipitant to the asphaltene-contair1ing product tested. U.S. Pat. No. 5,452,232 to Espinosa et al. discloses a method of detennining properties and yield of a hydrocarbon conversion product from the NIR spectrum of the feedstock. Mid infrared has also been used to determine the functional groups in asphaltenes by methyl ratio, paraflinic and naphthenic carbons, and alkyl side chain length.
Current practice for detennining the asphaltene stability of hydrocarbon process streams involves using some form of a heptane phase separation method. In that method, heptane is added to a sample from a hydrocarbon process stream, which dilutes the sample and decreases its absorbance. At the end point, the absorbance begins to increase due to asphaltene (or other condensed aromatic compound) precipitation. Asphaltene stability is than calculated based upon the absorbance readings. A typical method of this type is described in detail in “Standard Test Method for Detennination of Intrinsic Stability of Asphaltene-Containing Residues, Heavy Fuel Oils, and Crude Oils (n-Heptane Phase Separation; Optical Detection), published by ASTM International in May 2005 under “Designation D7157-05).” In addition to being time-consuming, a disadvantage of this method is that it requires multiple dilutions of the sample, each then being titrated with the n-heptane solvent for evaluation. These methods also significantly limit the ability to optimize the cracking process, especially under conditions of frequent changes in the type of crude oil in the feedstream.
There thus exists an ongoing need for improved methods of determining stability in hydrocarbon process streams. A particular need exists for quickly and efficiently detennining process stream stability with frequent changes in feed type.
SUMMARY
This invention relates to a method of predicting stability in a hydrocarbon process stream using a near infrared spectrum combined with a correlation model. In an aspect, the method includes measuring a stability value corresponding to each of a plurality of samples from the hydrocarbon process stream to produce a first dataset; selecting one or more wave numbers in the near infrared (“NIR”) spectrum as a first spectrum; using the first spectrum to determine an absorbance corresponding to each of the plurality of samples to produce a second dataset; incorporating the first dataset and the second dataset into at least one mathematical function to create the correlation model; selecting one or more wave numbers in the NIR spectrum as a second spectrum; using the second spectrum to measure an absorbance corresponding to one or more additional samples; calculating a predicted stability value corresponding to the additional sample(s) by using the measured absorbance as input for the correlation model and receiving as output the predicted stability; and optionally storing the received output in an electronic storage device and/or displaying the received output on a display device.
In another aspect, the method includes categorizing the hydrocarbon process stream into a plurality of different processes; selecting one of the processes; measuring a stability value corresponding to each of a plurality of samples from one of the processes to produce a first dataset; selecting one or more wave numbers in the NIR spectrum as a first spectrum; using the first spectrum to detennine an absorbance corresponding to each of the plurality of samples to produce a second dataset; incorporating the first dataset and the second dataset into at least one mathematical function to create the correlation model; selecting one or more wave numbers in the NIR spectrum as a second spectrum; using the second spectrum to measure an absorbance corresponding to one or more additional samples; calculating a predicted stability value corresponding to the additional sample(s) by using the measured absorbance as input for the correlation model and receiving as output the predicted stability; and optionally storing the received output in an electronic storage device and/or displaying the received output on a display device.
It is an advantage of the invention to provide a method of predicting the stability of a hydrocarbon process stream by defining a range of the NIR spectra and incorporating measured absorbance into one or more mathematical functions.
Another advantage of the invention is to provide a method of gathering stability data from a plurality of hydrocarbon process streams and creating a correlation model from that data to allow calculation of a predicted stability based solely upon NIR spectral measurements.
An additional advantage of the invention is to provide a method of analyzing a feed sample to select an optimum correlation model for use in analyzing the corresponding cracked residue sample.
A further advantage of the invention is to provide an improved eflicient method for analyzing cracked residue samples that reduces the amount of time required as compared to existing methodologies.
Another advantage of the invention is to provide a userfriendly method of analyzing cracked residue samples that requires less skill and training than current methodologies.
Yet another advantage of the invention is to provide an online method of analyzing cracked residue sample to optimize the cracking process.
Additional features and advantages are described herein, and will be apparent from, the following Detailed Description, Figures, and Examples.
System For Extending The Range Of Hydrocarbon Feeds In Gas Crackers
PATENT
System For Extending The Range Of Hydrocarbon Feeds In Gas Crackers
Inventors: James N. McCoy, Walter F. Filupeit, Barrington M. Hammond, David J. Duhon, Mark A. Rooney, Robert A. D. Strack, John R. Messinger
Original Assignee: ExxonMobil Chemical Patents Inc.
Patent number: 8025773
Issue date: Sep 27, 2011
Application number: 12/479,157
This application is a divisional of U.S. application Ser. No. 11/633,823 filed Dec. 5, 2006, now U.S. Pat. No. 7,560,019, which is hereby incorporated by reference.
FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION
Steam cracking, also referred to as pyrolysis, has long been used to crack various hydrocarbon feedstocks into olefins, preferably light olefins such as ethylene, propylene, and butenes. Conventional steam cracking utilizes a pyrolysis furnace that has two main sections: a convection section and a radiant section. The hydrocarbon feedstock typically enters the convection section of the fumace as a liquid (except for light feedstocks which enter as a vapor) wherein it is typically heated and vaporized by indirect contact with hot flue gas from the radiant section and by direct contact with steam. The vaporized feedstock and steam mixture is then introduced into the radiant section where the cracking takes place. The resulting products comprising olefins leave the pyrolysis furnace for further downstream processing, including quenching.
Pyrolysis involves heating the feedstock sufficiently to cause thennal decomposition of the larger molecules. The pyrolysis process, however, produces some molecules that tend to combine to form high molecular weight materials known as tar. Tar is a high-boiling point, viscous, reactive material that can foul equipment under certain conditions. In general, feedstocks containing higher boiling materials tend to produce greater quantities of tar.
Olefin gas cracker systems are nonnally designed to crack ethane, propane and on occasion butane, but typically lack the flexibility to crack heavier feedstocks, such as liquids, particularly those feedstocks that produce tar in amounts greater than one percent. As gas feeds tend to produce little tar, primary, secondary, and even tertiary transfer line exchangers (TLEs) are utilized to recover energy through the generation of high pressure and medium pressure steam, as the furnace efliluent cools from the fumace outlet to the quench tower inlet. TLE fouling on the process side is very limited with gas feeds, since the tar yields are very low.
The process gas is normally then fed to a quench tower wherein the process gas is further cooled by direct contact with quench water. Typically, the bottoms of the quench tower feed a quench drum, which functions as a three-phase separator, with a light hydrocarbon phase that floats on water and tar, which sinks in water, as the bottom phase. Even in the case of cracking ethane feed, the tar yield is high enough to cause the water leaving the quench drum to contain enough light tar, which has a specific gravity close to that of water, to cause downstream fouling of the quench circuit. This can result in the fouling of downstream heat exchangers and water stripping towers, which, when fouled, must be taken ofl1ine for cleaning.
Conventional steam cracking systems were effective for cracking high-quality feedstocks which contain a large fraction of light volatile hydrocarbons, such as gas oil and naphtha. However, steam cracking economics sometimes favor cracking lower cost feedstocks containing resids such as, by way of non-limiting examples, atmospheric residue, e.g., atmospheric pipe still bottoms, and crude oil. Crude oil and atmospheric residue often contain high molecular weight, non-volatile components with boiling points in excess of 590° C. (1 100° F.). The non-volatile components of these feedstocks lay down as coke in the convection section of conventional pyrolysis furnaces. Only very low levels of nonvolatile components can be tolerated in the convection section downstream of the point where the lighter components have fully vaporized.
Additionally, during transport, some naphthas or other lighter liquids are contaminated with heavy crude oil containing non-volatile components. Conventional pyrolysis furnaces do not have the flexibility to process residues, crudes, or many residue or crude contaminated gas oils or naphthas which comprise non-volatile components.
As indicated, in most commercial naphtha crackers, cooling of the effluent from the cracking fumace is normally achieved using a system of transfer line heat exchangers, a primary fractionator and a water quench tower or indirect condenser. The steam generated in transfer line exchangers can be used to drive large steam turbines which power the maj or compressors used elsewhere in the ethylene production unit. To obtain high energy-efliciency and power production in the steam turbines, it is necessary to superheat the steam produced in the transfer line exchangers.
Cracking heavier feeds, such as kerosenes and gas oils, may produce large amounts of tar, which can lead to rapid coking in the radiant section of the furnace as well as fouling in the transfer line exchangers preferred in lighter liquid cracking service, often requiring costly shutdowns for cleaning. Furthennore, if a quench liquid such as water is used, the heavy oils and tars may form stable emulsions that make it diflicult to dispose of excess quench water in an enviromnentally acceptable manner.
As indicated above, one technique used to further quench the effluent produced by steam cracking and remove the resulting heavy oils and tars employs a water quench tower in which the condensables are removed at near ambient conditions. Such a water quench technique has proven acceptable when cracking light gases, primarily ethane, although the quench water still may have significant amounts of hydrocarbons present, which serve to foul the water quench circuit. An altemative and more complex technique utilizes an oil quench with fractionation to remove the heavier tars, followed by a water quench to remove other condensables and complete the cooling. This technique is most practical for naphtha or heavy oil crackers which produce from about 1.0 wt % tar to greater than about 30 wt % tar.
Neither of these teclmiques is, however, entirely optimum for use in steam crackers that crack liquefiedpetroleum gases, light naphthas, and ethane that produce relatively little heavy oil and tar. One issue with these feedstocks stems from the fact that some of the heavy oils and tars produced when the pyrolysis efliluent of these feedstocks is quenched have approximately the same density as water and can form stable oil/water emulsions. Emulsion fonnation can render water quench operations ineffective, causing dilution steam generators to foul, and make disposal of excess quench water in an enviromnentally acceptable manner diflicult. Moreover, this further complicates the disposal of heavy oil and tar.
Process For The Conversion Of Heavy Feedstocks Such As Heavy Crude Oils And Distillation Residues
PATENT
Inventors: Romolo Montanari, Mario Marchionna, Nicoletta Panariti, Alberto Delbianco, Sergio Rosi
Original Assignees: ENI S.p.A., SNAMPROGETTI S.p.A., ENITECNOLOGIE S.p.A.
Patent number: 8017000
Issue date: Sep 13, 2011
Application number: 10/539,058
The conversion of heavy crude oils, bitumens from oil sands and oil residues into liquid products can be substantially effected by means of two methods: one exclusively thennal, the other through hydrogenating treatment.
Current studies are mainly directed towards hydrogenating treatment, as thermal processes have problems linked to the disposal of the by-products, particularly coke (also obtained in quantities higher than 30% by weight with respect to the feedstock) and to the poor quality of the conversion products.
The hydrogenating processes consist in treating the feedstock in the presence of hydrogen and suitable catalysts.
Hydroconversion technologies currently on the market use fixed bed or ebullated bed reactors and catalysts generally consisting of one or more transition metals (Mo, W, Ni, Co, etc.) supported on silica/alumina (or equivalent material).
Fixed bed technologies have considerable problems in treating particularly heavy feedstocks containing high percentages of heteroatoms, metals and asphaltenes, as these contaminants cause a rapid deactivation of the catalyst.
Ebullated bed technologies were developed and commercialized for treating these feedstocks; these provide interesting perfonnances but are complex and costly.
Hydrotreatment technologies operating with catalysts in dispersed phase can provide an attractive solution to the drawbacks encountered in the use of fixed bed or ebullated bed technologies. Slurry processes, in fact, combine the advantage of a wide flexibility for the feedstock with high performances in tenns of conversion and upgrading, making them, in principle, simpler from a technological point of view.
Slurry technologies are characterized by the presence of catalyst particles having very small average dimensions and being effectively dispersed in the medium: for this reason the hydrogenation processes are simpler and more efficient in all points of the reactor. The fonnation of coke is greatly reduced and the upgrading of the feedstock is high.
The catalyst can be introduced as a powder with sufliciently reduced dimensions or as an oil-soluble precursor. In the latter case, the active fonn of the catalyst (generally the metal sulfide) is formed in-situ by thennal decomposition of the compound used, during the reaction itself or after suitable pretreatment.
The metal constituents of the dispersed catalysts are generally one or more transition metals (preferably Mo, W, Ni, Co or Ru). Molybdenum and tungsten have much more satisfactory performances than nickel, cobalt or ruthenium and even more than vanadium and iron (N. Panariti et al., Appl. Catal. A: Gen. 2000, 204, 203).
Even though the use of dispersed catalysts solves most of the problems listed for the technologies described above, it still has disadvantages mainly linked to the life cycle of the catalyst itself and quality of the products obtained. The conditions of use of these catalysts (type of precursors, concentration, etc.) are, in fact, extremely important both from an economic point of view and also with respect to enviromnental impact. The catalyst can be used at a low concentration (a few hundreds of ppm) in a “once-through” configuration, but in this case the upgrading of the reaction products is generally insufficient (A. Delbianco et al., Chemtech, November 1995, 35). When operating with extremely active catalysts (for example molybdenum) and with higher concentrations of catalysts (thousands of ppm of metal), the quality of the product obtained is much better but a recycling of the catalyst is compulsory. The catalyst leaving the reactor can be recovered by separation from the product obtained by hydrotreatment (preferably from the bottom of the distillation colunm downstream of the reactor) by means of the conventional methods such as decanting, centrifugation or filtration (U .S. Pat. No. 3,240, 718; U.S. Pat. No. 4,762,812). Part of said catalyst can be recycled to the hydrogenation process without further treatment. The catalyst recovered using the known hydrotreatment processes, however, nonnally has a reduced activity with respect to the fresh catalyst making an appropriate regeneration step necessary in order to restore the catalytic activity and recycle at least part of said catalyst to the hydrotreatment reactor. Furthennore, these recovery processes of the catalyst are costly and also extremely complex from a technological point of view. All the hydroconversion processes described above allow more or less high conversion levels to be reached depending on the feedstock and type of technology used, but in any case generating a non-converted residue at the stability limit, herein called tar, which, from case to case, can vary from 15 to 85% of the initial feedstock. This product is used to produce fuel oil, bitumens or it can be used as a feedstock in gasification processes. In order to increase the overall conversion level of the cracking processes of residues, schemes were proposed which comprise the recycling of more or less significant quantities of tar in the cracking ur1it. In the case of hydroconversion processes with catalysts dispersed in slurry phase, the recycling of the tar also allows the recovery of the catalyst, insomuch that the same applicants in IT-95A001095 describe a process which allows the recovered catalyst to be recycled to the hydrotreatment reactor without the necessity of a further regeneration step, at the same time obtaining a goodquality product without the production of residue (zero residue refinery). This process comprises the following steps: mixing the heavy crude oil or distillation residue with a suitable hydrogenation catalyst and sending the mixture obtained to a hydrotreatment reactor into which hydrogen or a mixture of hydrogen and H2S is charged;
sending the stream containing the hydrotreatment reaction product and the catalyst in dispersed phase to a distillation zone in which the most volatile fractions (naphtha and gas oil) are separated;
sending the high-boiling fraction obtained in the distilla
tion step to a deasphalting step, thus producing two streams, one consisting of deasphalted oil (DAO), the other consisting of asphaltenes, catalyst in dispersed phase and possibly coke and enriched with metals coming from the initial feedstock;
Molecular Assemblies in Asphaltenes and Their High-Temperature Coke Products. 2. Levels of Molecular Organization
Energy Fuels, 2011, 25 (10), pp 4580–4585
Douglas L. Dorset*, Michael Siskin, and Leo D. Brown
Corporate Strategic Research, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, New Jersey 08801, United States
Abstract
An initial electron crystallographic investigation of the molecular organization of coke, described in a previous report, attempted to understand how long- or short-range order found, respectively, in sponge and shot coke, might be detected. Signs of local nucleation were found at very small selected area diameters with a test case based on the microcarbon residue test (MCRT), made on a sponge coke-forming sweet vacuum tower bottoms (VTB) feed. In MCRT experiments on sweet VTB, a 490 °C annealing temperature was used instead of the 500 °C employed in our earlier study. At 5 min annealing time, electron diffraction patterns revealed the formation of small nuclei within a 0.25 µm diameter. The smallest detected arcing of (002) reflection, found at 5 min annealing time, persists for all longer annealing times; only the distribution of these angles decreased. This result was repeated in a time sequence based on MCRT trials performed at 490 °C on a Maya crude vacuum residuum, known to produce shot coke in coker units. In addition, polarized light microscopy results are in accord with the electron diffraction observations, revealing the overall distribution of smaller coherent paracrystalline domains.
Full Text Source (Subscription or Fee): http://pubs.acs.org/doi/abs/10.1021/ef200872q
New heterogeneous catalysts for demercaptanization of petroleum and petroleum products
Chemistry and Technology of Fuels and Oils, Volume 47, Number 3, 194-200 (2011)
T. T. Yarmamedov (1)
A. D. Éfendi (1)
M. R. Manafov (1)
I. G. Melikova (1)
Z. A. Zaitseva (1)
1. M. F. Nagiev Institute of Chemical Problems of the NationalAcademy of Sciences of Azerbaidzhan, Baku, Azerbaidzhan
Abstract
Full Text Source (Subscription or Fee): http://www.springerlink.com/content/t625782522485r08/
Chlorine determination in crude oil fractions after digestion using microwave-induceced combustion
Br J Anal Chem 2011, 03, 119–123
Juliana Severo Fagundes Pereira (A), Diogo Pompéu de Moraes (A), Edson Irineu Muller (A), Juliano Smanioto Barin (A), Liange de Oliveira Diehl (A), Márcia Foster Mesko (B), Valderi Luiz Dressler (A), Érico Marlon de Moraes Flores (A)
A) Department of Chemistry, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil
B) Chemistry and Geoscience Institute, Universidade Federal de Pelotas, 96010-610, Pelotas, RS, Brazil
Abstract
A procedure for chlorine determination by ion chromatography (IC) in crude oil fractions (atmospheric distillation residue and gas oil) was proposed after digestion using microwave-induced combustion (MIC). Using the proposed procedure sample digestion was complete in less than 30 min and up to eight samples could be digested that is an important aspect for routine analysis.
The proposed procedure by MIC was performed in closed quartz vessels under oxygen pressure (20 bar) and using 50 µl of 6 mol l-1 NH4NO3 for the ignition step. Some parameters of the combustion process were studied, as the kind and the suitability of the absorbing solution (H2O, (NH4)2CO3 and NH4OH), oxygen pressure and sample mass. Certified reference materials (CRM) and spiked samples were used to evaluate the accuracy. The agreement using CRM was higher than 97% and the recoveries using reflux step were in the range of 98 to 102% using 25 mmol-1 NH4OH as absorbing solution. For results comparison, Cl was also determined by ICP-MS and no statistical difference was observed compared to results obtained by IC. The limit of detection (LOD, 3s) for Cl obtained by IC and ICP-MS was 1.2 and 6.6 µg g-1, respectively. The residual carbon content in digests obtained after MIC procedure was lower than 1%.
Free Full Text Source: http://www.brjac.com.br/Revista_BrJAC_1_3.pdf#page=17
Model for Gasification of Residual Fuels from Petroleum Refineries Using the Equation Oriented (EO) Approach
Ind. Eng. Chem. Res., 2011, 50 (5), pp 2628–2640
Jorge E. Marin-Sanchez* and Miguel A. Rodriguez-Toral
Instituto Mexicano del Petroleo
Abstract
Syngas has many uses, including: as fuel in IGCC plants, or as raw material for other chemical manufacturing processes
Using an equation oriented (EO) approach where the process model is set up as a Non Linear Algebraic Equations System and simultaneously solved, the model gives the syngas composition, with CO, H2, CO2, CH4, H2S, HCN, NH3, N2, O2, COS, and H2O, as well as the slag composition, with NiS, FeS, V2O3, ashes, and no reacted hydrocarbon. The slag mass flow and composition calculation is an important feature not considered by previously published models. A sensitivity analysis was made in order to show the effect of input variables.
Full Text Source (Subscription or Fee): http://pubs.acs.org/doi/abs/10.1021/ie100663w
Study On Variation In Viscosity Of Visbreaking Residue
45th International Petroleum Conference, June 13, 2011, Bratislava, Slovak Republic
D. Stratiev 1, R. Dinkov, I. Shishkova, K.Kirilov
stratiev.dicho@neftochim.bg
Chief Process Engineer Department, Lukoil Neftochim Bourgas JLC, Bulgaria,
Abstract
Distillation properties were identified as per GOST 10120 (Bogdanov distillation) and ASTM D-1160 standard. The asphaltene and coke content in visbreaker residue was also determined. For the analyzed samples of visbreaking residue authors determined that the viscosity does not correlate with the asphaltene content. Viscosities of the diesel fraction (IBP-3600?) and heavy vacuum gas oil (360-5100?), that are contained in the visbreaking residue were calculated based on these fractions distillation property data, their density, and using the simulation software ChemCad. By using the model for blending heavy residual fractions of the linear programming software RPMS viscosities of the residual fractions (boiling above 5100?) from the analyzed samples of visbreaking residue were calculated. As a result of these calculations and the distillation property data of the visbreaking residue analyzed samples authors determined that the variation in viscosity of visbreaking residue is due to different content of diesel fraction, heavy vacuum gas oil and heavy residual fraction.
Molecular Size and Size Distribution of Petroleum Residue
Energy Fuels, 2011, 25 (5), pp 2109–2114
Zhentao Chen*, Suoqi Zhao, Zhiming Xu, Jinsen Gao, and Chunming Xu*
State Key Laboratory of Heavy Oil Processing and Faculty of Chemical Science and Engineering, China University of Petroleum, Changping, Beijing 102249, People’s Republic of China
Abstract
Average molecule diameters and size distributions of the residue and its five SFEF cuts were determined from bulk-phase diffusion coefficients, which were measured at 308 K by a diaphragm cell. All five cuts show obvious polydispersity in size, with the end-cut possessing the broadest size distribution. A strong tendency of asphaltenes to aggregate suggests that the large size of the end-cut results from the aggregation of asphaltene molecules. The average hydrodynamic diameter of the end-cut was estimated to be 4.7 nm, as opposed to a range of 1.1-1.7 nm for the four narrow fractions. The average diameters of all five cuts can be correlated with their average molecular weight. In comparison to the size range of 1.1-4.7 nm for the narrow cuts, the feedstocks of the whole residue have a smaller size distribution of 1.4-3.9 nm.
Full Text Source (Subscription or Fee): http://pubs.acs.org/doi/abs/10.1021/ef200128m?mi=s5eqhk&af=R&pageSize=20&searchText=track-etched+polycarbonate
Sample preparation procedure for the determination of polycyclic aromatic hydrocarbons in petroleum vacuum residue and bitumen
Analytical and Bioanalytical Chemistry, Volume 401, Number 3, 1059-1069
From the issue entitled "Imaging Techniques with Synchrotron Radiation (pp. 783-870)"
Ewelina Gilgenast (1)
Grzegorz Boczkaj (1)
Andrzej Przyjazny (2)
Marian Kaminski (1)
1. Chemical Faculty, Department of Chemical and Process Engineering, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdansk, Poland
2. Chemistry & Biochemistry Department, Kettering University, 1700 West Third Avenue, Flint, MI 48504, USA
Abstract
Limits of quantitation of the studied PAHs in materials of this type range from tens of nanograms per kilogram to <20 µg/kg. The studies revealed that in order to separate most of interferences from the analytes without a significant loss of PAHs, it is necessary to use size exclusion chromatography as the first step of sample preparation, followed by adsorption using normal-phase liquid chromatography. The use of orthogonal separation procedure described in the paper allows the isolation of only a group of unsubstituted and substituted aromatic hydrocarbons with a specific range of molar mass. The lower the required limit of quantitation of PAHs, the larger is the scale of preparative liquid chromatography in both steps of sample preparation needed.
Free Full Text Source: http://www.springerlink.com/content/b64414835rl3842g/
Subscribe to:
Posts (Atom)